WO2009069925A1

WO2009069925A1 - Lens holder capable of adjusting location of optical axis of lens

Info

Publication number: WO2009069925A1
Application number: PCT/KR2008/006937
Authority: WO
Inventors: Gyeongil Kweon
Original assignee: Nanophotonics Co., Ltd.
Priority date: 2007-11-30
Filing date: 2008-11-25
Publication date: 2009-06-04

Abstract

Disclosed is a lens holder having a location adjusting unit capable of locating an optical axis of a rotationally symmetrical imaging lens at a particular point on a sensor plane of an image sensor. The lens holder includes a lower base, an intermediate member, an upper plate member, a first location adjusting unit, and a second location adjusting unit. The lower base includes a fixing unit that is fixed to a camera board whereon an image sensor is mounted. The intermediate member is positioned between the upper plate member and the lower base. The upper plate member and the lower base are inserted into and coupled with the intermediate member. The upper plate member includes a coupling unit that is coupled with the lens in such a way that the optical axis of the lens is aligned perpendicularly to a sensor plane of the image sensor.

Description

LENS HOLDER CAPABLE OF ADJUSTING LOCATION OF

OPTICAL AXIS OF LENS

Technical Field

[1] The present invention relates to a lens holder. More particularly, the present invention relates to a lens holder having location adjusting units capable of locating the optical axis of a rotationally symmetrical imaging lens at a particular point on the sensor plane of an image sensor. Background Art

[2] FIG. 1 is an exploded perspective view illustrating a small-sized closed circuit television (CCTV) called a board camera. A board camera 100 includes a camera board 120, a lens holder 130 and an imaging lens 110.In general, the camera board 120 includes electronic parts 123 and a CCD or a CMOS image sensor 122, which is mounted on an electronic circuit formed on a printed circuit board (PCB) 121.The image sensor 122, in general, has a rectangular sensor plane 124 having an aspect ratio of 4: 3, 1: 1 or 16: 9.

[3] In general, the imaging lens 110 has a rotationally symmetrical shape about an optical axis 111.The imaging lens 110 includes at least one lens element 114 mounted within a lens barrel 115. An image of an object (not shown) captured by the imaging lens 110 is formed on an image plane 113, which is a sub-region of a focal plane 112.The focal plane 112 is a plane perpendicular to the optical axis 111 and exist at the opposite side of the object with respect to the lens, ie, at the image side of the imaging lens 110.Distance from the nodal point of the imaging lens 110 to the focal plane 112 is substantially identical to the effective focal length of the imaging lens 110.The image of an object is formed on the image plane 113 within the focal plane 112.Due to a rotationally symmetrical structure of the imaging lens 110, the image plane 113 has a circular shape in general.

[4] In order to obtain a clear image from an imaging system such as the one illustrated in

Fig. 1, the distance in the optical axis direction between the imaging lens 110 and the sensor plane 124 must be finely adjusted so that the focal plane 112 of the imaging lens 110 coincides with the sensor plane 124.When the sensor plane 124 coincides with the focal plane 112, the image is referred to as "focused". Further, when the sensor plane 124 is fully contained within the image plane 113, no vignetting occurs. If vignetting occurs, then regions having no image signals exist on a monitor connected to the camera 100. In a simile, it is like a photograph with edges cutout. In order to avoid vignetting effect, an imaging system is usually designed with an image plane 113 that is sufficiently larger than the sensor plane 124.

[5] In order to obtain a clear image that is free from vignetting effect, the following set of conditions must be satisfied. First, the image plane 113 must have a sufficiently large size such that the sensor plane 124 can be fully included within the image plane 113.Next, the distance in the optical axis direction between the imaging lens 110 and the sensor plane 124 must be precisely set. Thirdly, the center of the image plane 113 must substantially match with the center of the sensor plane 124.

[6] The lens holder 130 illustrated illustrated in FIG. 1 is a device necessary for such a mechanical alignment. A lens holder 130 employed in a small imaging system is usually comprised of a fixing part 131 and a holder barrel 132. The fixing part 131 has a shape of a hollow box in order to receive the image sensor 122 therein. In order for the lens holder 130 to be physically combined with the camera board 120, the camera board 120 is formed with through holes 125 into which board fixing screws 126 are inserted, and the fixing part 131 of the lens holder 130 is formed with matching coupling holes 133. To assemble the board camera, the lens holder 130 is placed over the image sensor 122 on the camera board 120, and then the lens holder 130 is fixed to the camera board 120 using board fixing screws 126.

[7] A lens coupling part 116 is formed at the lower part of the lens barrel 115, and the holder barrel 132 of the lens holder 130 is formed with a lens coupling hole 134 corresponding to the lens coupling part 116. Thus, after the imaging lens 110 is inserted into the holder barrel 132, the distance between the imaging lens 110 and the sensor plane 124 can be decreased by rotating the imaging lens in a clockwise direction. On the other hand, the distance between the imaging lens 110 and the sensor plane 124 can be increased by rotating the imaging lens in a counterclockwise direction. In order to obtain a sharply focused image, the camera is connected to a video monitor, and the imaging lens 110 is rotated in the clockwise or the counterclockwise direction until the video image becomes clear.

[8] For low-priced imaging systems such as the one shown in FIG. 1, it is often the case that the location of the optical axis 111 of the imaging lens 110 does not coincide with the center of the sensor plane 124. Since CCD image sensors 122 are usually manufactured in a dip type, non-negligible amount of alignment error occurs when a CCD image sensor 122 is mounted on a PCB 121. Further, when the lens holder 130 is fixed to the PCB 121 using board fixing screws 126, more alignment error is accumulated because both the lens holder 130 and the PCB 121 have manufacturing tolerances. Therefore, even if the imaging lens 110 and the lens holder 130 are perfect by themselves, the optical axis 111 of the imaging lens 110 in a finally assembled board camera does not match with the center of the sensor plane 124 of the CCD image sensor 122 In this field of the industry, typical alignment error is considered to be about + 0.3mm.

[9] For an ordinary imaging system, it hardly matters if the optical axis 111 of the imaging lens 110 does not exactly coincide with the center of the sensor plane 124. Since the size of the image plane is larger than the size of the sensor plane, vignetting effects does not occur, and it is difficult for a naked eye to notice the fact that the center of the image plane 113 does not match with the center of a video monitor screen. However, in a special technological field such as the one of extracting a desired image using an image processing technique from a raw image obtained using a fisheye lens, such an alignment error causes significant amount of image distortion.

[10] Fisheye lens generally refers to a lens whereof the field of view is 160 or more and the incidence angle of an incident ray is substantially proportional to the image height on the image plane. Numerous application fields exist where a fisheye lens with a field of view of 180 ° or more is required such as security / surveillance or entertainment. Fig. 2 is a virtual indoor scene generated using a computer by a professor Paul Bourke, for which it is assumed that a fisheye lens has been used having a field of view of 180 ° and following an ideal equidistance projection scheme. Fig. 2 has a square shape with both the lateral and the longitudinal dimensions measuring as 250 pixels. Therefore, the location of the optical axis, that is, the center coordinate of the image plane is (125.5, 125.5), and the image height r of an incident ray having an incidence angle of 90 ° is given as rtfI / 2) = 125.5 1 = 124.5.

[11] FIG. 3 is an exemplary panoramic image extracted from FIG. 2 using the image processing algorithm presented in the eighth embodiment of the reference 1. As can be seen from FIG. 3, vertical lines on four walls all appear as straight lines. The phenomenon of vertical lines appearing as straight lines is a characteristic of an accurate panoramic image. On the other hand, FIG. 4 is a result of applying the same image processing algorithm as that of FIG. 3, whereof a positional error of 10 pixels in the lateral direction and 10 pixels in the longitudinal direction is applied on purpose to the center coordinate of the image plane. As can be seen from FIG. 4, the image is significantly distorted. As such, for an imaging system involving image processing, there is a need to accurately adjust or measure the center coordinate of an image plane, in other words, the location of optical axis.

[12] Additionally, since a fisheye lens has a large field of view, the field of view of an image captured by an imaging system becomes severely asymmetric if the center of the image plane does not coincide with the center of the sensor plane. In other words, the field of view may significantly differ between the left and the right or between the top and the bottom. Due to a large field of view of a fisheye lens, the alignment error can be easily noticed by naked eyes.

[13] Considering these facts, for an imaging system using a wide angle lens such as a fisheye lens, the location of the optical axis needs to be precisely adjusted whether or not there is an image processing stage involved. However, it is not always desirable to locate the optical axis of a fisheye lens at the center of a sensor plane. For example, let's assume that it is desired to monitor a wide-area by horizontally installing a fisheye lens having a field of view of 180 ° on an indoor wall. For such an imaging system, it will be desirable to monitor the left and the right sides equally widely by making the horizontal field of view of the lens symmetrical. However, it will be desirable to have the vertical field of view asymmetrical. This is because the region above the horizon with respect to the optical axis of the fisheye lens is usually indoor ceiling and requires less attention. Considering these facts, the desirable sizes of a sensor plane 524 and an image plane 513, and relative positions according are given as shown in FIG. 5.

[14] In FIG. 5, the image sensor plane 524 is assumed as that of an ordinary image sensor having an aspect ratio 4: 3 between the length B of vertical sides 524T and 524B and the length V of horizontal sides 524L and 524R. If the field of view of a fisheye lens is 180 °, then the half angle θ ₂ is 90 °. In such a case, in order to obtain an image having a horizontal field of view of 180 ° while maximally utilizing the pixels of an image sensor, it is desirable that the rim of the image plane 513 makes contact with the horizontal sides 524L and 524R of the sensor plane 524. Thus, preferably, the size of the image plane 513 is given by Equation 1.

[15]

[16] Equation 1

[18]

[19] Meanwhile, in a vertical direction, it is preferred that all areas under the horizon are monitored. Thus, the center O of the image plane 513, that is, the optical axis is preferably aligned such that the rim of the image plane 513 makes contact with the left side 524L, the right side 524R and the bottom side 524B of the sensor plane 524.

[20] In various application examples as described above, the optical axis of a lens needs to be exactly aligned at a particular point on the sensor plane. A criterion for the alignment accuracy can be the pixel size of an image sensor. For the case of a 1 / 3-inch CCD sensor having video graphics array (VGA) resolution, the lateral and the longitudinal dimension of each pixel is 7.5 / M. Thus, preferably, the optical axis of the lens must be aligned within an area smaller than the size of one pixel. However, it is impossible that the lens and the image sensor are aligned with such accuracy by using an ordinary lens holder as shown in FIG. One.

[21] Another prerequisite condition for obtaining a clear image is to remove stray light. In other words, only the rays focused by the lens must reach the image plane. If light rays reach the image plane without passing through the lens, the light rays serve as noise. For the board camera shown in FIG. 1, after the lens, the lens holder and the camera board are assembled together, stray light rays other than intended light rays having passed through the lens do not reach the sensor plane of the image sensor. In such a structure, the camera comprises an optically sealed structure. Therefore, the lens holder provides optical sealing effect as well as mechanical alignment capability.

[22] Reference 2 discloses a lens holder used for assembling and adjusting a relatively large lens or a lens subassembly. The lens holder includes an adjusting mount ring, a removable retaining lens ring for detachably coupling the lens or the lens assembly with the adjusting mount ring, two adjustment set screws and one pressure pin mechanism. The two adjustment set screws and one pressure pin mechanism are inserted into the adjusting mount ring at an interval of 120 °.

[23] When taking a photograph using an optical equipment such as a camera phone or a digital camera, if the user is not an expert, then hand shaking occurs while taking pictures, and obtained image is low in quality. In order to prevent image deterioration due to hand trembling or vibration, a vibration isolating device has been developed. Reference 3 provides a lens holder for mechanically compensating the vibration.

[24] According to the lens holder in the related art, a movable frame, a lens holding frame and a stationary frame are sequentially arranged, and the lens holding frame is disposed between the movable frame and the stationary frame, so that the total length of the lens holder in the optical axis direction can be reduced. The three frames are roughly in doughnut shapes and are substantially similar in shapes and inner diameters. The vibration isolating device includes a drive means having two piezoelectric elements to shake the lens holding frame in two independent directions. In order to detect the current position of the lens holding frame, a pair of LED light sources are mounted on the lens holding frame, and a pair of photosensors are equipped on the corresponding position on the stationary frame. High frequency voltage is used to drive the piezoelectric elements.

[25] According to the art verified in reference 3, a lens can be independently moved in two orthogonal directions perpendicular to the optical axis. However, since it is not a purpose of the said art to adjust the location of the optical axis, the optical axis of the lens cannot be located and fixed to a particular point on a sensor plane of an image sensor. Further, optical sealing effect necessary for a normal imaging system cannot be obtained.

[26] Reference 4 discloses a mount shift device for a CCTV lens, which has a purpose similar to that of the present invention. The reference 4 relates to a mount shift device for a low cost CCTV lens, which is capable of easily compensating for deviation between the optical axis of a lens and the light receiving plane in a camera body, which may occur when a screw mount for a lens is attached to the camera body. The mount shift device includes a mount frame that is coupled to the camera body, a lens frame for supporting a lens having an optical axis, a shift ring and a bias member for shifting the lens frame in two perpendicular directions with respect to the mount frame . Since the lens frame must be adjusted with respect to the mount frame in two orthogonal directions, it is defective in that the lens frame cannot be individually adjusted in two orthogonal directions.

[27] Reference 5 discloses a lens adjusting apparatus capable of compensating for eccentricity of a first lens element, which exerts most significant influence upon modulation transfer function (MTF) characteristics, so that eccentricity of a lens, which frequently occurs while assembling an imaging optical system that uses a small lens element such as digital camera or camera phone, and results in reduction of product yield, can be avoided. The lens adjusting apparatus of the invention includes a barrel support plate for restricting movement of a barrel having multiple of lenses, a frame disposed above the barrel support plate and including a side portion formed at an outer peripheral portion of the barrel, two fine adjustors and at least one elastic member. The two fine adjustors are mounted on the side portion of the frame to finely adjust the position of the first lens nearest to the object side among the lenses mounted in the lens barrel. The elastic member provides the first lens with elastic force from the opposite side of the fine adjustors.

[28] The invention in reference 4 differs from the invention in reference 5 in that the invention in reference 4 moves the entire lens in a plane perpendicular to the optical axis, while the invention in reference 5 moves only one lens element which is most sensitive to reduction in product yield by eccentricity in a plane perpendicular to the optical axis. However, similar to the related arts of the references 1 through 4, the lens adjusting apparatus cannot be independently adjusted in two directions perpendicular to the optical axis.

[29] Reference 6 discloses another embodiment of a lens holder for mechanically compensating the vibration. The lens holder of said invention includes a stationary support plate, an X-direction movable member, an X-direction guide device, a Y-direction movable member and a Y-direction guide device. The X-direction movable member is supported by the stationary support plate, and movable only in the X-direction in a plane perpendicular to an optical axis. The X-direction guide device ensures the X- direction movable member to move only in the X-direction. The Y-direction movable member is supported by the X-direction movable member, and movable only along the Y-direction in a plane perpendicular to the optical axis. The Y-direction guide device ensures the Y-direction movable member to move only in the Y-direction. The X- direction movable member is positioned between the stationary support plate and the Y-direction movable member and is formed with three ball retaining through holes that form a triangle. Three balls are inserted into the ball retaining through holes so that the balls make contact with the stationary support plate and the Y-direction movable member while rotatable in any direction.

[30] In order to compensate vibration using said device, separate drive means are required for the X-direction and the Y-direction. The drive means is comprised of a pair of electromagnets for a X-direction actuator and a Y-direction actuator. Further, the three balls prevent the lens holder from wobbling during shake correction operation. However, similar to other lens holders for shake correction, this lens holder is defective in that this lens holder cannot be used for the purpose of semi-permanently adjusting and fixing the position of an optical axis.

[31] Reference 7 discloses an adjusting apparatus capable of shifting a projection lens of a projector in a direction perpendicular to the optical axis. The adjusting apparatus of the said invention includes a projection lens module for enlarging incident light and projecting the enlarged incident light on a screen, a movable bracket for supporting the projection lens module, a stationary bracket for supporting the movable bracket such that the movable bracket can be raised or lowered, a shift unit installed between the stationary bracket and the movable bracket to selectively move the movable bracket up and down according to a rotation direction, and an elastic module installed at the lower portion of the projection lens module to elastically support the projection lens module.

[32] However, the adjusting apparatus can adjust the location of the optical axis of a lens only in one direction. Further, in order to support a heavy projection lens module, the structure of the adjusting apparatus is complicated.

[33] Reference 8 discloses a lens holder capable of adjusting the location of the optical axis of a projection lens independently in two directions perpendicular to the optical axis. However, since the lens holder uses a cam to shift a movable plate, the movable range is limited to an operation range of the cam. Further, since the lens holder uses a worm gear as well as the cam, operation mechanism of the lens holder is unnecessarily complicated.

[34]

[35] [Reference 1] Gyeong-il Kweon, "Methods of obtaining panoramic images using rotationally symmetric wide-angle lenses and devices approximately", Korean patent application no. 10-2008-0022039, date of filing March 10, 2008.

[36] [Reference 2] Walter L. Wilson, "Quick-set precision optical holder", US patent registration no. 5,457,577, date of registration October 10, 1995.

[37] [Reference 3] Akira Kosaka and Tetsuro Kanbara, "Lens movable in a perpendicular direction to the optical axis", US patent registration no. 6,005,723, date of registration December 21, 1999. [38] [Reference 4] Sisito Takayas and Ito Minora, "Mount shift device of a lens for a

CCTV camera ", Korean patent registration no. 10-0397441, date of registration August

27, 2003. [39] [Reference 5] Yun Seok Choi, Ho Seop Jeong, Hyung Jin Kim, Jae Ho Baik, "Lens adjusting apparatus and a body tube assembly manufacturing method using the same",

Korean patent registration no. 10-0691192, date of registration February 28, 2007. [40] [Reference 6] Shuzo Seo, "Stage apparatus and camera shake correction apparatus using the stage apparatus", US patent registration no. 7,379,093, date of registration

May 27, 2008. [41] [Reference 7] Kyoung Choul Jang, "Apparatus for adjusting shift of projection lens of projector", Korean patent registration no. 10-0571779, date of registration April 11,

2006. [42] [Reference 8] Sheng-Feng Lin and Yao Jen Kang, "Projection lens shifting mechanism", US patent registration no. 6,909,560, date of registration June 21, 2005.

Disclosure of invention

Technical Problem [43] The present invention has been made in order to solve the problems occurring in the related art, and an object of the present invention is to provide a lens holder capable of exactly aligning the optical axis of a rotationally symmetrical imaging lens at a particular point on a sensor plane of an image sensor.

Technical Solution

[44] In order to accomplish the above object, according to one aspect of the present invention, there is provided a lens holder including an upper plate member that can be combined with a lens that is rotationally symmetrical about an optical axis, a lower base that can be fixed to a camera board which is under the lower base, an intermediate member into which the upper plate member and the lower base are inserted, a first location adjusting unit that moves the upper plate member in a Y-axis direction relative to the intermediate member, and a second location adjusting unit that moves the intermediate member in an X-axis direction relative to the lower base.

[45] The upper plate member, the intermediate member and the lower base are all perforated in the optical axis direction of a lens that is combined to the upper plate member. Thus, an image of an object captured by the lens can be formed on a sensor plane without being interrupted by the upper plate member, the intermediate member and the lower base. Relative movements of the upper plate member, the intermediate member and the lower base are impossible in the optical axis direction. The upper plate member is formed with a lens coupling hole corresponding to a lens coupling part of the lens, so that the lens can be inserted into the upper plate member. Further, the distance between the lens and the sensor plane can be adjusted by rotating the lens in the clockwise or the counterclockwise direction.

Advantageous Effects

[46] According to the present invention, the optical axis of a rotationally symmetrical imaging lens can be aligned at a particular point on a sensor plane, thereby achieving an image that is perfectly symmetrical in the lateral and the longitudinal directions.

Further, an image processing error can be eliminated in an imaging system involving an image processing, so that a satisfactory image can be obtained.

Brief Description of Drawings [47] FIG. 1 is an exploded perspective view illustrating a small-sized closed circuit television (CCTV) called a board camera; [48] FIG. 2 is a virtual indoor landscape generated using a computer by professor Paul

Bourke, where it is assumed that a fisheye lens having a field of view of 180 ° and following an ideal equidistance projection scheme is used; [49] FIG. 3 is an exemplary panoramic image extracted from FIG. 2, where an image processing algorithm presented in embodiment 8 of reference 1 is applied; [50] FIG. 4 is a result of applying the same image processing algorithm as that of FIG. 3, wherein a center coordinate of an image plane applying the image processing algorithm is deviated from a center coordinate of an actual image plane by an error corresponding to lateral misalignment of 10 pixels and longitudinal misalignment of 10 pixels. [51] FIG. 5 is a schematic diagram illustrating an arrangement plan of a fisheye lens and the sensor plane of an image sensor according to a prior art; [52] FIG. 6 is an exploded perspective view showing a board camera employing a lens holder according to the first embodiment of the present invention; [53] FIG. 7 is a perspective view showing an assembled state of the board camera shown in FIG. 6;

[54] FIG. 8 is a sectional view taken along line I-I of FIG. 7;

[55] FIGS. 9 and 10 are sectional plan views taken along line III-III of FIG. 7 to show an operational state of moving the lens in the Y-axis direction; [56] FIGS. 11 and 12 are sectional plan views taken along line II-II of FIG. 7 to show an operational state of moving the lens in the X-axis direction; [57] FIG. 13 is an exploded perspective view showing a lens holder according to the second embodiment of the present invention; [58] FIG. 14 is a longitudinal sectional view showing the lens holder according to the second embodiment of the present invention; [59] FIGS. 15 and 16 are sectional plan views of the lens holder according to the second embodiment of the present invention;

[60] FIG. 17 is an exploded perspective view showing a lens holder according to the third embodiment of the present invention;

[61] FIG. 18 is a longitudinal sectional view showing the lens holder according to the third embodiment of the present invention;

[62] FIGS. 19 and 20 are schematic diagrams illustrating the operational principle of a lens holder according to the third embodiment of the present invention;

[63] FIG. 21 is a conceptual diagram to understand the exact rotational angles of the upper plate member and the intermediate member for the off-centered location of the optical axis with respect to the center of the sensor plane to be given as (x, y);

[64] FIG. 22 is an exploded perspective view showing a C-mount (Cine Mount) or a CS- mount (Cine Short Mount) camera employing a lens holder according to the fourth embodiment of the present invention;

[65] FIG. 23 is a longitudinal sectional view of the camera employing the lens holder according to the fourth embodiment of the present invention;

[66] FIG. 24 is an exploded perspective view showing a lens holder according to the fifth embodiment of the present invention;

[67] FIG. 25 is a perspective view showing an assembled lens holder; and

[68] FIG. 26 is a sectional view of an assembled lens holder.

[69] <Description of Reference Numbers of Main Parts in Drawings>

[610] 610: lens 620: camera board

[71] 630: lens holder 640: upper plate member

[72] 650: intermediate member 660: lower base

[73] 670: first location adjusting unit

[74] 680: second location adjusting unit

Mode for the Invention

[75] Present, preferred embodiments of the present invention will be described in detail with reference to FIGS. 6 through 26.

[76] First embodiment

[77] A lens holder according to a first embodiment (Al) of the present invention will be described below with reference to accompanying drawings. Fig. 6 is an exploded perspective view showing a board camera 600 employing a lens holder 630 according to the first embodiment of the present invention. A rectangular coordinate system is used to easily understand the drawings. In this rectangular coordinate system, the Z-axis coincides with the optical axis 611 of a lens 610, the Y-axis is parallel to one of the lateral side of a sensor plane 624 of an image sensor, and the X-axis is parallel to another lateral side of the sensor plane 624 that is perpendicular to the said lateral side of the sensor plane 624.

[78] The lens 610 is rotationally symmetrical about the optical axis 611, and a multiple of lens elements 614 are accommodated within a lens barrel 615 and a lens coupling part 616 is provided at a lower portion of the lens barrel 615. In addition, an annular protrusion 617 is formed at an upper end of the lens coupling part 616 in order to block stray light that may reach the sensor plane 624 of the image sensor. The lens holder 630 includes an upper plate member 640 to which a lens 610 is combined, a lower base 660 that is fixed to a camera board 620 and an intermediate member 650 into which the upper plate member 640 and the lower base 660 are inserted. In addition, the lens holder 630 includes a first location adjusting unit 670 for moving the upper plate member 640 in the Y-axis direction relative to the intermediate member 650 and a second location adjusting unit 680 for moving the intermediate member 650 in the X- axis direction relative to the lower base 660.

[79] The upper plate member 640 includes a plate member 641 having a rectangular shape, a downward insertion part 642 having a rectangular shape and protruding from a lower portion of the plate member 641, and a lens coupling hole 643 formed in the Z- axis direction through the plate member 641 and the downward insertion part 642.In addition, the first and the second inner through holes 644 and 645 are formed in the Y- axis direction on one lateral side (g) and on the opposing side (h ) of the downward insertion part 642, respectively.

[80] An insertion hole 651 is formed within the intermediate member 650 into which the downward insertion part 642 of the upper plate member 640 is inserted. The insertion hole 651 is in a form of an open-ended pipe with a square cross-section. In addition, as shown in FIG. 6, the intermediate member 650 is formed at one lateral side (c) and the opposing side (d) approximately with the first and the second outer through holes 654 and 655, which are directed in the Y-axis direction, corresponding to the first and the second inner through holes 644 and 645, respectively. In addition, the intermediate member 650 is formed at lower portions of one lateral side (a) and the opposing side (b) approximately with the third and the fourth outer through holes 656 and 657, which extend in the X-axis direction, respectively .

[81] The length of the downward insertion part 642 of the upper plate member 640 in the

X-axis direction is identical to the length of the insertion hole in the X-axis direction, and the length of the downward insertion part 642 of the upper plate member 640 in the Y-axis direction is shorter than the length of the insertion hole in the Y-axis direction. In other words, the length of the downward insertion part in the Y-axis direction is shorter than that in the X-axis direction.

[82] The lower base 660 includes an upward insertion part 661, which is provided at an upper portion of the lower base 660, a fixing part 662, which is provided at a lower portion of the lower base 660, and an inner chamber 663 formed within the lower base and penetrates the lower base in the Z- axis direction. The upward insertion part 661 is inserted into the insertion hole 651 of the intermediate member 650.The upward insertion part 661 is formed at one lateral side (e) and the opposing side (f) approximately with the third and the fourth inner through holes 666 and 667, which are directed in the X-axis direction.

[83] The length of the upward insertion part 661 of the lower base in the Y-axis direction is identical to the length of the insertion hole in the Y-axis direction, and the length of the upward insertion part 661 in the X- axis direction is shorter than the length of the insertion hole in the X-axis direction. That is, the length of the upward insertion part 661 in the X-axis direction is shorter than the length of the upward insertion part 661 in the Y-axis direction.

[84] Board through holes 625 are formed in a printed circuit board 621 on which electronic parts are mounted, and board fixing screws 626 combine the fixing part 662 to the camera board 620. To this end, board fixing screw coupling holes 664 are formed at a lower end of the fixing part 662 corresponding to the board through holes 625 of the printed circuit board 621.

[85] The inner chamber 663 is in a form of a rectangular pipe with open upper and lower ends. Thus, an incident ray originating from an object converges toward the sensor plane of the image sensor 622 due to the imaging properties of the lens 610, wherein the incident ray can reach the sensor plane 624 without being blocked by the lens coupling hole 643 of the upper plate member 640, the insertion hole 651 of the intermediate member 650, and the inner chamber 663 of the lower base 660.In addition, since the image sensor 622 is inserted into the inner chamber 663 of the lower base 660, the distance between the lens 610 and the sensor plane 624 is shortened and stray light that can reach the sensor plane 624 is effectively blocked.

[86] The first location adjusting unit 670 includes a first guide pin 671, which is inserted into the first outer through hole 654 and the first inner through hole 644, and a first adjustment screw 672, which is inserted into the second outer through hole 655 and the second inner through hole 645.The downward insertion part 642 of the upper plate member 640 is inserted into the insertion hole 651 of the intermediate member 650 and then coupled with the first guide pin 671 through the first inner through hole 644, so that the upper plate member 640 can linearly move only in the Y-axis direction along the first guide pin 671 relative to the intermediate member 650. Snap ring coupling parts 675, which are coupled with snap rings 673, are provided at both ends of the first guide pin 671 and the length of the first guide pin 671 is longer than the length of the intermediate member 650 in the Y-axis direction. Therefore, in a state where the first guide pin 671 is coupled with the upper plate member 640 and the intermediate member 650, the snap ring coupling parts 675 of the first guide pin 671 protrude from one lateral side (c) and the opposing side (d) of the intermediate member 650, which is obvious from FIG. 7 and FIG. 9.When the snap rings 673 are coupled with the snap ring coupling parts 675, the first guide pin 671 is prevented from being lost from the intermediate member 650.

[87] Referring again to FIG. 6, the first adjustment screw 672 includes a screw head 674 provided at one end of the first adjustment screw 672, a snap ring coupling part 677 provided at the other end of the first adjustment screw 672, and a screw part 676 provided between the screw head 674 and the snap ring coupling part 677.The second inner through hole 645, which is formed in the downward insertion part 642 of the upper plate member 640, is formed at an inner peripheral surface according with a female screw that corresponds to the screw part 676 of the first adjustment screw 672.In addition, the length of the first adjustment screw 672 is longer than the length of the intermediate member 650 in the Y-axis direction. Therefore, when the first adjustment screw 672 is coupled with the upper plate member 640 and the intermediate member 650, the screw head 674 and the snap ring coupling part 677 of the first adjustment screw 672 protrude from one lateral side (c) and the opposing side (d) of the intermediate member 650 (see, Fig. 9). When a snap ring 673 is coupled to the snap ring coupling part 677, the first adjustment screw 672 is prevented from being lost from the intermediate member 650.In addition, it is possible to move the upper plate member 640 in the Y-axis direction relative to the intermediate member 650 by adjusting the first adjustment screw 672.

[88] The second location adjusting unit 680 includes a second guide pin 681, which is inserted into the third outer through hole 656 and the third inner through hole 666, and a second adjustment screw 682, which is inserted into the fourth outer through hole 657 and the fourth inner through hole 667.The upward insertion part 661 of the lower base 660 is inserted into the insertion hole 651 of the intermediate member 650 and then coupled with the second guide pin 681 through the third inner through hole 666, so that the intermediate member 650 can linearly move only in the X-axis direction along the second guide pin 681 relative to the lower base 660. The shape and the size of the second guide pin 681 are substantially identical to those of the first guide pin 671, and the shape and the size of the second adjustment screw 682 are substantially identical to those of the first adjustment screw 672.Additionally, since the operational principle of the second location adjusting unit 680 is similar to that of the first location adjusting unit 670, it will not be further described below in order to avoid redundancy.

[89] It is possible to align the optical axis 611 of a lens on a specific position on the sensor plane 624 by using the first and the second location adjusting units 670 and 680. In general, the optical axis can be aligned on the exact center of the sensor plane. However, depending on application examples, the optical axis can be aligned on a specific position on the sensor plane other than the center of the sensor plane. Once the optical axis of the lens has been aligned on a specific position on the sensor plane, it is necessary to fix the lens holder in order to prevent the optical axis of the lens from deviating from the specific position. Provided for such a purpose is a holder fixing unit which include a holder fixing screw coupling hole 659 formed on an outer wall of the intermediate member and a holder fixing screw 658.

[90] The holder fixing screw 658 is screwed into the holder fixing screw coupling hole

659 formed at the outer wall of the intermediate member 650. The holder fixing screw coupling hole 659 penetrates through the wall of the intermediate member 650. Thus, as the holder fixing screw 658 is fastened, the holder fixing screw 658 protrudes into the insertion hole of the intermediate member 650, thus making contact with the downward insertion part 642 of the upper plate member 640 or the upward insertion part 661 of the lower base 660.When the holder fixing screw is sufficiently fastened, the relative movement of the lens holder becomes impossible due to friction between the holder fixing screw and the downward insertion part of the upper plate member or the upward insertion part of the lower base. Thus, after the optical axis of the lens has been precisely aligned by adjusting the first and the second adjustment screws, the lens holder can be fixed by using holder fixing screws, so that the optical axis of the lens is prevented from deviating from the specific position.

[91] Since the lens coupling part 616 is prepared in a form of a male screw and the lens coupling hole 643 of the upper plate member 640 is prepared in a form of a female screw, a focused image can be obtained by rotating the lens in the clockwise or the counterclockwise direction. After a focused image is obtained, it is necessary to fix the lens so that the lens won't rotate any more. To this end, a lens fixing screw 652 is provided.

[92] The lens fixing screw 652 is screwed into a lens fixing screw coupling hole 646, which is formed on the downward insertion part 642 of the upper plate member 640, through a lens fixing screw insertion hole 653 formed on one lateral side (c ) of the intermediate member 650.Since the lens fixing screw insertion hole 653 has a diameter that is much larger than that of the lens fixing screw, the lens fixing screw can be screwed into the lens fixing screw coupling hole without being interrupted by the intermediate member. The lens fixing screw coupling hole is extended from the outer wall of the downward insertion part to the lens coupling hole. Thus, if the lens fixing screw is sufficiently fastened, the lens fixing screw protrudes into the lens coupling hole of the upper plate member, thereby making contact with the lens coupling part. Therefore, the lens can be prevented from rotating due to friction between the lens fixing screw and the lens coupling part.

[93] Referring to FIG. 6, the lens is combined with the lens holder by the male screw formed in the lens coupling part and the lens coupling hole, which is a female screw formed in the upper plate member. However, this is only an example of a lens coupling unit for combining the lens with the lens holder. For example, a dedicated coupling unit, such as a F-mount or a T-mount is used in expensive equipments such as a camera. The embodiment of the present invention is applicable to the entire lens holders having general lens coupling units, and not limited to a lens holder having a lens coupling hole.

[94] FIG. 7 is a perspective view showing an assembled state of the board camera shown in FIG. 6, and FIG. 8 is a sectional view taken along line I-I of FIG. 7.As is clear from FIG. 7, the plate member 641 has a size substantially identical to that of the intermediate member 650, and the plate member 641 has a rectangular shape that completely covers the insertion hole 651 of the intermediate member 650. In particular, the plate member 641 has a sufficiently large size for preventing a gap being formed between the plate member 641 and the insertion hole 651 of the intermediate member 650, even if the optical axis of the lens is deviated from the center of the sensor plane by the maximum amount using the first or the second adjustment screws. Due to such a structure, stray light, which is not a ray refracted by the lens and converging toward the image plane, is prevented from leaking into a gap between the upper plate member and the intermediate member. Likewise, the fixing part of the lower base is securely combined with the camera board without forming a gap therebetween by using board fixing screws. Therefore, the lens holder according to an embodiment of the present invention always maintains an optically shielded structure regardless of the operational state of the lens holder.

[95] Supreme, the assembling and the operation of the lens holder according to the first embodiment of the present invention will be described. In order to assemble the lens holder 630, the upper plate member 640 is inserted into the intermediate member 650 and the first guide pin 671 is inserted into the first outer through hole 654 such that the first guide pin 671 passes through the first inner through hole 644.Then, snap rings 673 are coupled to snap ring coupling parts 675 provided at both ends of the first guide pin 671.In the same way, the first adjustment screw 674 is inserted into the second outer through hole 655 on one lateral side ( d) of the intermediate member 650 such that the first adjustment screw 672 passes through the second inner through hole 645.Then, the screw head 674 of the first adjustment screw is rotated in the clockwise direction so that the first adjustment screw can pass through the female screw part of the second inner through hole 645 formed in the downward insertion part 642 of the upper plate member 640 in the Y-axis direction. As the screw head 674 of the first ad- justment screw is rotated, the snap ring coupling part 677 of the first adjustment screw 672 protrudes out of one lateral side (c) of the intermediate member 650. Then, the snap ring 673 can be coupled to the snap ring coupling part 677 of the first adjustment screw 672.

[96] Then, the intermediate member 650 is fitted around the upward insertion part 661 of the lower base 660 and the second guide pin 681 and the second adjustment screw 682 are coupled to the lower base 660 similar to the first location adjusting unit 670. After that, the holder fixing screw 658 and the lens fixing screw 652 are inserted into the holder fixing screw coupling hole 659 and the lens fixing screw coupling hole 646, thereby completing the assemblage of the lens holder 630 according to the first embodiment of the present invention.

[97] After the lens holder 630 has been assembled, the lens holder 630 is combined with the camera board 620 by using board fixing screws 626. Then, the lens coupling part 616 of the lens 610 is screwed into the lens coupling hole 643 of the upper plate member 640. After that, the height of the lens 610 is adjusted to obtain a focused image by rotating the lens 610 in the clockwise or the counterclockwise direction. After adjustment has been finished, the holder fixing screw 658 and the lens fixing screw 652 are fastened to securely fix the lens and the lens holder.

[98] FIGS. 9 and 10 are sectional plan views taken along line III-III of FIG. 7 to show an operational state of moving the lens in the Y-axis direction, and FIGS. 11 and 12 are sectional plan views taken along line II- II of FIG. 7 to show an operational state of moving the lens in the X-axis direction.

[99] As shown in FIG. 9, if the first adjustment screw 672 is unscrewed (that is, if the first adjustment screw 672 is rotated in the counterclockwise direction), the screw part 676 of the first adjustment screw 672 is rotated within the female screw part of the second inner through hole 645. However, the first adjustment screw 672 itself cannot move back and forth due to the screw head 674 and the snap ring 673. Accordingly, if the first adjustment screw 672 is unscrewed, the upper plate member 640 moves in the opposite direction. In other words, if the first adjustment screw 672 is loosened, instead of the first adjustment screw 672 moving back in the plus (+) Y-axis direction (upward direction in the drawing), the upper plate member 640 moves forward in the minus (-) Y-axis direction (downward direction in the drawing). In the reverse direction, as shown in FIG. 10, if the first adjustment screw 672 is fastened (that is, if the first adjustment screw 672 is rotated in the clockwise direction), instead of the first adjustment screw 672 moving forward in the minus Y-axis direction, the upper plate member 640 moves back in the plus Y-axis direction. In this way, the position of the optical axis of the lens in the Y-axis direction relative to the sensor plane 624 can be easily adjusted.

[100] Referring to FIG. 9, the diameter of the first adjustment screw 672 is gradually reduced from the screw head 674 to the snap ring coupling part 677.additionally, the second outer through hole 655 and the second inner through hole 645, which are coupled to the first adjustment screw 672, have matching sizes to the corresponding diameters of the first adjustment screw 672. Therefore, the first adjustment screw 672 can be combined to the lens hold in one direction only.

[101] Similarly, referring to FIG. 11, if the second adjustment screw 682 is loosened, the intermediate member 650 moves back in the plus X-axis direction (right direction in the drawing). In the reverse direction, as shown in FIG. 12, if the second adjustment screw 682 is fastened, the intermediate member 650 moves forward in the minus X- axis direction (left direction in the drawing).

[102] After the optical axis has been aligned on a desired position on the sensor plane 624 using such operations, the upper plate member 640, the intermediate member 650 and the lower base 660 are fixed relative to each other by fastening the holder fixing screws 658.In addition, if images are in sharp focus, the lens fixing screw 652 can be fastened as shown in FIG. 6, thereby fixing the lens 610 relative to the lens holder 630.

[103]

[104] Second Embodiment

[105] FIG. 13 is an exploded perspective view showing a lens holder according to the second embodiment of the present invention, and FIG. 14 is a longitudinal sectional view showing the lens holder according to the second embodiment of the present invention. Similar to the first embodiment, a rectangular coordinate system is used in order to easily understand the drawings. In a rectangular coordinate system, the Z-axis coincides with the optical axis 1111 of a lens 1110, the Y-axis is parallel to one lateral side of a sensor plane 1124 of the image sensor, and the X-axis is parallel to another lateral side of the sensor plane that is perpendicular to the said lateral side of the sensor plane.

[106] As shown in FIG. 13, the lens holder 1130 according to the second embodiment (A2) of the present invention includes an upper plate member 1140 into which a lens 1110 is combined, a lower base 1160 that is fixed to a camera board 1120 underneath, an intermediate member 1150 into which the upper plate member 1140 and the lower base 1160 are inserted, a first location adjusting unit for moving the upper plate member 1140 in the Y-axis direction relative to the intermediate member 1150 and a second location adjusting unit for moving the intermediate member 1150 in the X-axis direction relative to the lower base 1160.

[107] The upper plate member 1140 includes a plate member 1141 having a rectangular shape, a downward insertion part 1142 having a rectangular shape and protruding from a lower portion of the plate member 1141, and a lens coupling hole 1143 formed in the Z- axis direction through the plate member 1141 and the downward insertion part 1142. In addition, coil spring fixing screw coupling holes 1144 are formed in the Y-axis direction on one lateral side (g) and the opposing side (h) of the plate member 1141, and a lens fixing screw coupling hole 1146 is formed at one side (i) of the downward insertion part 1142, and a first leaf spring fixing screw coupling hole is formed at another side (j) of the downward insertion part 1142.In addition, upper coil spring insertion holes 1145 (see, Fig. 14 ) are formed in the Z-axis direction on two opposing edges of the downward insertion part 1142.

[108] An insertion hole 1151 is formed within the intermediate member 1150, into which the downward insertion part 1142 of the upper plate member 1140 is inserted. The insertion hole 1151 is in a form of an open-ended pipe with square cross-section. In addition, the intermediate member 1150 is formed at one lateral side (a) approximately with a lens fixing screw insertion hole 1153, which is directed in the X-axis direction, and the first fixing screw coupling holes 1156 are formed at both sides of the lens fixing screw insertion hole. Further, the intermediate member 1150 is formed on lower portion of the opposing side (b) approximately with a second adjustment screw coupling hole 1155.In addition, the intermediate member 1150 is formed at an upper portion of one side (c) approximately with a first adjustment screw coupling hole 1154, which is directed in the Y- axis direction, and is formed at a lower portion of the opposing side according with a second fixing screw coupling hole 1157.

[109] The lower base 1160 includes an upward insertion part 1161, which is provided at an upper portion of the lower base 1160, a fixing part 1162, which is provided at a lower portion of the lower base 1160, and an inner chamber 1163 formed inside the lower base 1160.Lower coil spring insertion holes 1165 are formed at two opposing edges of the upward insertion part 1161, and a coil spring locking plate 1166 is provided at the fixing part 1162.The fixing part 1162 is fixed to the camera board 1120 using board fixing screws, on which an image sensor 1122 and electronic parts are mounted. To this end, board through holes 1125 are formed in the camera board 1120 and board fixing screw coupling holes 1164 are formed at corresponding positions on lower end of the fixing part 1162, so that the lower base 1160 can be securely fixed to the camera board 1120 by using board fixing screws 1126.

[110] An upper hook part of a coil spring 1191 is locked with a coil spring fixing screw

1192, which is coupled to the plate member 1141 of the upper plate member 1140, by passing through the upper coil spring insertion hole 1145 formed in the downward insertion part 1142 of the upper plate member 1140, and a lower hook part of the coil spring 1191 is locked with the coil spring locking plate 1166, which is formed in the fixing part 1162, by passing through the lower coil spring insertion hole 1165 formed in the upward insertion part 1161 of the lower base 1160.

[I ll] The first location adjusting unit includes a first leaf spring 1172, a first leaf spring fixing screw coupling hole formed at one side (j) of the downward insertion part 1142, a first leaf spring fixing screw 1173 for fixing the first leaf spring 1172 on said one side, a first adjustment screw coupling hole 1154 formed at one side (c ) of the intermediate member 1150, and a first adjustment screw 1171 coupled into the first adjustment screw coupling hole. The first leaf spring 1172 is curved in a semicircular shape and one end of the first leaf spring 1172 is fixed to one side (j) of the downward insertion part 1142 by the first leaf spring fixing screw 1173, so that the first leaf spring 1172 pushes out the upper plate member 1140 in the negative Y-axis direction. [112] The first adjustment screw 1171 supports one side of the downward insertion part

1142 of the upper plate member 1140 through the first adjustment screw coupling hole

1154 formed at one side (c) of the intermediate member 1150. Thus, it is possible to adjust the distance between the upper plate member 1140 and the intermediate member 1150 in the Y-axis direction by fastening or loosening the first adjustment screw 1171. The first leaf spring 1172 elastically pushes the upper plate member 1140 in the opposite direction to that by the first adjustment screw 1171, so that the interval in the Y-axis direction between the upper plate member 1140 and the intermediate member

1150 can be stably maintained. After the adjustment has been finished, the first fixing screws 1175, which are coupled into the first fixing screw coupling holes 1156 formed at one side (a) of the intermediate member 1150, are fastened to prevent the upper plate member 1140 from moving in the Y-axis direction relative to the intermediate member 1150.

[113] Meanwhile, the second location adjusting unit includes a second leaf spring 1182, a second leaf spring fixing screw coupling hole 1167 formed at one side (e) of the upward insertion part 1161, a second leaf spring fixing screw 1183 for fixing the second leaf spring 1182 on said one side, a second adjustment screw coupling hole

1155 formed at one side (b) of the intermediate member 1150, and a second adjustment screw 1181 coupled into the second adjustment screw coupling hole. The second leaf spring 1182 has a shape identical to that of the first leaf spring 1172, and one end of the second leaf spring 1182 is fixed to one side (e) of the upward insertion part 1161 of the lower base 1160 by the second leaf spring fixing screw 1183, so that the second leaf spring 1182 pushes out the intermediate member 1150 in the X-axis direction. Therefore, similar to the first location adjusting unit, the second location adjusting unit can adjust the interval in the X-axis direction between the intermediate member 1150 and the lower base 1160.After the adjustment has been finished, the second fixing screws 1185, which are coupled into the second fixing screw coupling holes 1157 formed at one side (d) of the intermediate member 1150, are fastened to prevent the intermediate member 1150 from moving in the X-axis direction relative to the lower base 1160. [114] Meanwhile, referring to FIG. 14, the lens holder according to the second embodiment of the present invention employs a coil spring 1191 to prevent the intervals in the optical axis direction among the upper plate member 1140, the intermediate member 150 and the lower base 1160 from becoming loose. The upper hook parts of the coil springs 1191 are locked to the coil spring fixing screws 1192, which are coupled to the plate member 1141 in the Y-axis direction, by passing through the upper coil spring insertion holes 1145, and the lower hook parts of the coil springs 1191 are locked to the coil spring locking plate 1166 of the lower base 1160 by passing through the lower coil spring insertion holes 1165, so that the upper plate member 1140 and the lower base 1160 are elastically pulling each other by the coil springs 1191.Accordingly, a predetermined interval can be maintained between the upper plate member 1140 and the lower base 1160.

[115] FIGS. 15 and 16 are sectional plan views of the lens holder according to the second embodiment of the present invention, and illustrate the principle for adjusting an interval between the intermediate member 1150 and the lower base 1160 in the X-axis direction by adjusting the second adjustment screw 1181. Referring to FIG. 15, if the second adjustment screw 1181 is loosened, the intermediate member 1150 is pushed away to the right direction due to elastic force of the second leaf spring 1182, and as the result, the optical axis is moved to the right from the center of the sensor plane 1124.

[116] In contrast, as shown in FIG. 16, if the second adjustment screw 1181 is fastened, the second adjustment screw pushes the lower base 1160 to the right. However, since the lower base is fixed to the camera board, repulsive force is applied retroactively to the intermediate member, and the intermediate member 1150 is moved to the left. Therefore, the optical axis is moved to the left from the center of the sensor plane 1124, and the second leaf spring 1182 becomes compressed.

[117] In the same manner, the interval between the upper plate member 1140 and the intermediate member 1150 in the Y-axis direction can be adjusted by adjusting the first adjustment screw 1171.This will be appreciated by a person having ordinary skill in the art, so it will not be further described.

[118]

[119] Third Embodiment

[120] FIG. 17 is an exploded perspective view showing a lens holder according to the third embodiment (A3) of the present invention, and FIG. 18 is a longitudinal sectional view showing the lens holder according to the third embodiment of the present invention. The lens holder 1430 according to the third embodiment of the present invention includes an upper plate member 1440, an intermediate member 1450 and a lower base 1460. Similar to the first embodiment, a rectangular coordinate system is used in order to easily understand the drawings. In this rectangular coordinate system, the Z-axis coincides with the optical axis 1411 of a lens 1410, the Y-axis is parallel to one lateral side of a sensor plane 1424 of an image sensor, and the X-axis is parallel to another lateral side of the sensor plane 1424 that is perpendicular to the said one lateral side of the sensor plane 1424.

[121] The lower base 1460 includes a lower end receiving part 1461, which is provided at an upper portion of the lower base 1460, and a fixing part 1462, which is provided at a lower portion of the lower base 1460.In addition, a lower end coupling hole 1463 is formed within the lower end receiving part 1461 and an inner chamber 1464 is formed within the fixing part 1462. The lower end receiving part 1461 has a cylindrical outer surface and the lower end coupling hole 1463 is in a form of a cylindrical pipe. In addition, the rotational symmetry axis of the lower end coupling hole 1463 coincides with the rotational symmetry axis of the outer surface of the lower end receiving part 1461. Meanwhile, the inner chamber 1464 is in a form of a square box. The rotational symmetry axis of the lower end receiving part 1461 passes through the center of the inner chamber 1464. This common axis is the lower base central axis 1413.

[122] Lower base fixing screw coupling holes 1466 are formed along the outer peripheral surface of the lower end receiving part 1461 at a regular interval. The lower base fixing screw coupling holes 1466 are extended from the outer peripheral surface of the lower end receiving part 1461 to the lower end coupling hole 1463.

[123] The lower base 1460 is fixed to a camera board 1420 by board fixing screws. Board fixing screw coupling holes 1465 are formed on the lower end of the fixing part 1462 of the lower base 1460 in correspondence with board through holes 1425 of the camera board.

[124] An image sensor 1422, which is mounted on the camera board 1420, is inserted into the inner chamber 1464, and the lower base central axis 1413 approximately coincides with the center of the sensor plane 1424 of the image sensor 1422 (see, Fig. 18). The expression "Approximately coincides" signifies that the lower base central axis 1413, which perpendicularly passes through the center of the lower base 1460, is designed and assembled to match with the center of the sensor plane 1424 of the image sensor, but it does not exactly match with the center of the sensor plane 1424 of the image sensor due to manufacturing and assembling tolerances.

[125] The intermediate member 1450 includes an intermediate receiving part 1451, which is provided at an upper portion of the intermediate member 1450, and an intermediate coupling part 1452, which is provided at a lower portion of the intermediate member 1450. In addition, an intermediate coupling hole 1453 is formed within the intermediate receiving part 1451, and an intermediate through hole 1454 is formed within the intermediate coupling part 1452.An intermediate handle 1455 is provided at an outer peripheral surface of the intermediate receiving part 1451 to allow a user to easily rotate the intermediate member 1450 by hand. The "intermediate handle" refers to protrusions in the Z- axis direction formed on the outer peripheral surface of the intermediate receiving part 1451.

[126] The intermediate coupling hole 1453 has a cylindrical shape identical to that of the lower end coupling hole 1463. The rotational symmetry axis of the intermediate coupling hole 1453 is the intermediate member central axis 1412 (see, Fig. 18). In addition, the intermediate through hole 1454 has a cylindrical shape.

[127] According to the scope of the present invention, the rotational symmetry axis of the intermediate coupling hole 1453 needs not coincide with the rotational symmetry axis of the intermediate through hole 1454. Nevertheless, it is desirable if they do coincide. The radius of the intermediate through hole 1454 is smaller than that of the intermediate coupling hole 1453. That is, the intermediate coupling hole 1453 and the intermediate through hole 1454 form a two-step pipe structure and a circular step is formed at the boundary between the intermediate coupling hole 1453 and the intermediate through hole 1454.

[128] The outer peripheral surface of the intermediate coupling part 1452 has a rotationally symmetric shape with a V-shaped intermediate member rail groove 1458 (see, Fig. 18). However, the rotational symmetry axis of the outer peripheral surface of the intermediate coupling part 1452 does not coincide with the intermediate member central axis 1412.In other words, the intermediate member central axis 1412 is off-centered with respect to the rotational symmetry axis of the outer peripheral surface of the intermediate coupling part 1452.

[129] The radius of the outer peripheral surface of the intermediate coupling part 1452 is identical to the radius of the lower end coupling hole 1463 formed within the lower end receiving part 1461. Thus, the intermediate coupling part 1452 of the intermediate member 1450 is combined with the lower end coupling hole 1463 of the lower base 1460 in such a manner that the intermediate coupling part 1452 can freely rotate for full 360 degrees around the lower base central axis. In this case, the intermediate member central axis 1412 rotates around the lower base central axis 1413.

[130] Lower base fixing screw coupling holes 1466 are formed at the outer peripheral surface of the lower end receiving part 1461 of the lower base at a regular interval. Preferably, three lower base fixing screw coupling holes 1466 are formed at the outer peripheral surface of the lower end receiving part 1461 at an angular interval of 120 degrees. In addition, the central axis 1466a of a lower base fixing screw coupling hole 1466 is located slightly below the central axis 1458a of a intermediate member rail groove 1458.

[131] Referring to FIG. 18, when lower base fixing screws 1467 are coupled into the lower base fixing screw coupling holes 1466, the lower base fixing screws 1467 fix the intermediate coupling part 1452 of the intermediate member 1450 in such a way that the intermediate coupling part 1452 of the intermediate member 1450 is prevented from being separated from the lower end receiving part 1461 of the lower base 1460.In this case, if the lower base fixing screws 1467 are loosened, the intermediate member 1450 can rotate with respect to the lower base 1460.In contrast, if the lower base fixing screws 1467 are fastened, the lower base fixing screws exert strong frictional force on intermediate coupling part 1452 of the intermediate member 1450, and the intermediate member 1450 becomes unable to rotate.

[132] In addition, since the central axis of the lower base fixing screw 1467 is located below the central axis 1458a of the V-shaped intermediate member rail groove 1458, the intermediate member 1450 is pulled downward to the lower base 1460 as the lower base fixing screws 1467 are fastened. Thus, the intermediate member 1450 becomes progressively more difficult to rotate with respect to the lower base 1460 as the lower base fixing screws 1467 are fastened harder.

[133] The upper plate member 1440 includes a plate member 1441, which is provided at an upper portion of the upper plate member 1440, and an upper end coupling part 1442, which is provided at a lower portion of the upper plate member 1440. The outer peripheral surface of the upper end coupling part 1442 has a rotationally symmetrical shape with V-shaped upper plate rail groove 1448 formed thereon. The radius of the outer peripheral surface of the upper end coupling part is identical to that of the intermediate coupling hole 1453 formed within the intermediate receiving part 1451, and the upper plate member central axis 1411 is off-centered with respect to the rotational symmetry axis of the upper end coupling part by a predetermined interval.

[134] The plate member 1441 has a disc shape, and has a diameter sufficiently large for completely covering the intermediate coupling hole 1453 of the intermediate receiving part 1451, and an upper handle 1444 is formed at the outer peripheral surface. The shape of the upper handle 1444 is identical to that of the intermediate handle 1455.For the convenience in manipulation, the central axis of the upper handle 1444 preferably coincides with the rotational symmetry axis of the outer peripheral surface of the upper end coupling part 1442 .

[135] A lens coupling hole 1443 is formed within the upper plate member 1440, which penetrates the upper plate member in the optical axis direction. A lens coupling part 1416 of a lens 1410 is screwed into the lens coupling hole 1443. Since the lens coupling part 1416 of a lens 1410 that is rotationally symmetric about an optical axis is screwed into the lens coupling hole 1443 of the upper plate member 1440 , the central axis 1411 of the lens coupling hole 1443 coincides with the optical axis as well as the upper plate member central axis. A lens coupling hole is the simplest and the cheapest coupling unit for coupling a lens to a lens holder.

[136] In addition, a lens fixing screw coupling hole 1445 is formed at the outer peripheral surface of the plate member 1441.The lens fixing screw coupling hole 1445 extends from the outer peripheral surface of the plate member 1441 to the lens coupling hole 1443 .

[137] A conservative, the operational mechanism of the lens holder according to the third embodiment of the present invention will be described. FIGS. 19 and 20 are schematic diagrams illustrating the principle of a lens holder according to the third embodiment of the present invention. With reference to FIGS. 19 and 20, the lower base 1460 has a symmetrical structure in the longitudinal direction as well as in the lateral direction. The lower end coupling hole 1463 of the lower base 1460 is in a form of a cylindrical pipe with a radius R ₁ . In addition, the center O of the lower end coupling hole 1463 coincides with the center of a sensor plane 1424.The outer wall 1462b of the fixing part 1462 of the lower base 1460 may have a cylindrical shape having a center coinciding with the center of the lower end coupling hole 1463, or it may have a box shape having an inner chamber similar to the lower bases according to the first and the second embodiments.

[138] The outer peripheral surface 1452b of the intermediate coupling part 1452 of the intermediate member 1450 has a size identical to the size of the lower end coupling hole 1463. according, in a state where the intermediate coupling part 1452 is coupled into the lower end coupling hole 1463, the intermediate member 1450 can freely rotate full 360 with respect to the lower base 1460, and while the intermediate member 1450 rotates, the center of the outer peripheral surface 1452b of the intermediate coupling part 1452 is not changed. In other words, the lower end coupling hole 1463 of the lower base 1460 acts as a guide for the outer peripheral surface 1452b of the intermediate coupling part 1452 of the intermediate member 1450.

[139] An intermediate coupling hole 1453 of the intermediate member 1450 is in a form of a cylindrical pipe with a radius R ₂ . However, the center O 'of the intermediate coupling hole 1453 of the intermediate member 1450 does not coincide with the center O of the outer peripheral surface 1452b of the intermediate coupling part 1452. In FIG. 19, the distance between the two centers is R. according, when the intermediate member 1450 is rotated with respect to the lower base 1460, the position of the center O of the outer peripheral surface 1452b (see Fig. 19) of the intermediate coupling part 1452 of the intermediate member 1450 is not changed, but the center O 'of the intermediate coupling hole 1453 rotates around the center O of the outer peripheral surface 1452b drawing a circle with a radius R.

[140] Similarly, the outer peripheral surface 1442b of the upper end coupling part 1442 of an upper plate member 1440 has a size that is identical to the size of the intermediate coupling hole 1453 of the intermediate member 1450.Depending on, in a state where the upper end coupling part 1442 is coupled to the intermediate coupling hole 1453, the upper plate member 1440 can freely rotate full 360 ° with respect to the intermediate member 1450. the upper plate member 1440 rotates with respect to the intermediate member 1450, the center of the outer peripheral surface 1442b of the upper end coupling part 1442 is not changed. In other words, the intermediate coupling hole 1453 of the intermediate member 1450 acts as a guide for the outer peripheral surface 1442b of the upper end coupling part 1442 of the upper plate member 1440.

[141] Disregarding thread lines, the lens coupling hole 1443 of the upper plate member

1440 is in a form of a cylindrical pipe with a radius R ₃ . However, the center O "of the lens coupling hole 1443 of the upper plate member 1440 does not coincide with the center O 'of the outer peripheral surface 1442b of the upper end coupling part 1442 of the upper plate member 1440. The distance between the two centers is also R. according, when the upper plate member 1440 rotates with respect to the intermediate member 1450, the position of the center O 'of the outer peripheral surface 1442b of the upper end coupling part 1442 of the upper plate member 1440 is not changed, but the center O "of the lens coupling hole 1443 rotates around the center O'of the outer peripheral surface 1442b of the upper end coupling part 1442 drawing a circle with a radius R.

[142] Resultantly, the center O "of the lens coupling hole 1443 of the upper plate member 1440 is able to rotate around the center O 'of the intermediate coupling hole 1453 of the intermediate member 1450 drawing a circle with a radius R, and the center O 'of the intermediate coupling hole 1453 of the intermediate member 1450 is able to rotate around the center O of the lower end coupling hole 1463 of the lower base 1460 drawing a circle with a radius R. superior, for the simplicity of description , the center O of the lower end coupling hole 1463 of the lower base 1460 will be referred to as a "center O of the lower base", the center O 'of the intermediate coupling hole 1453 of the intermediate member 1450 will be referred to as a "center of the intermediate member", and the center O "of the lens coupling hole 1443 of the upper plate member 1440 will be referred to as a" center O "of the upper plate member".

[143] In FIG. 19, the center O 'of the intermediate member 1450 is spaced apart from the center O of the lower base 1460 by a distance R in the X-axis direction, and the center O "of the upper plate member 1440 is spaced apart from the center O 'of the intermediate member 1450 by a distance R in the negative X-axis direction.Resultantly, the center O of the lower base 1460 is coincident with the center O "of the upper plate member 1440. additional, a lens 1410, which has a rotationally symmetrical shape, is combined into the lens coupling hole 1443 of the upper plate member 1440. Accordingly, the optical axis 1411 of the lens 1410, the central axis 1411 of the lens coupling hole 1443 (ie, the central axis of the upper plate member 1440), the central axis 1413 of the lower base 1460, and the center of the sensor plane 1424 all coincide with each other. As a result, the optical axis 1411 is precisely located at the center of the sensor plane 1424.

[144] Meanwhile, in FIG. 20, the center O 'of the intermediate member 1450 is spaced apart from the center O of the lower base 1460 by a distance R in the positive Y-axis direction, and the center O "of the upper plate member 1440 is spaced apart from the center O 'of the intermediate member 1450 by a distance R in the positive Y-axis direction.Depending on, the optical axis is spaced apart from the center of the sensor plane 1424 by a distance 2R in the positive Y-axis direction.In such a manner, the intermediate member 1450 and the upper plate member 1440 can be rotated by appropriate angles, so that the optical axis can be aligned anywhere within a circle having a radius 2R from the center of the sensor plane 1424.

[145] FIG. 21 is a conceptual diagram to understand the exact rotational angles of the upper plate member 1440 and the intermediate member 1450 for the off-centered position of the optical axis 1411 from the center of the sensor plane 1424 to be given by (x, y) . In FIG. 21, the center of the sensor plane 1424 is taken as the origin O of a coordinate system. The origin O of the coordinate system is also coincident with the center of the inner chamber 1464 of the lower base 1460.In this case, the distance R ₀ from the origin O to the position of the optical axis O "is given as in Eq . 2.

[146]

[147] Equation 2

[148]

R, = J ^χ2 + y

[149] An azimuth angle θ subtended by a line segment from the origin O to the position O "of the optical axis and the X-axis is given as in Eq. 3. [150]

[151] Equation 3

[153] according to Eqs. 4 and 5 can be obtained.

[154]

[155] Equation 4

[156] x = R ₀ co $ θ

[157]

[158] Equation 5

[159] y = R _a mθ

[160]

[161] MMeeaannwwhhiillee ,, tthhee α center O 'of the intermediate member 1450 is located at a distance R from the origin O, and the azimuth angle subtended by a line segment from the origin O to the center O' of the intermediate member 1450 and the X-axis is 0. In addition, the center O "of the upper plate member 1440 is located at a distance R from the center O 'of the intermediate member 1450, and the azimuth angle subtended by a line segment from the center O "of the upper plate member 1440 to the center O 'of the intermediate member 1450 and the X-axis is 0. according, Eqs. 6 and 7 can be obtained.

[162]

[163] Equation 6

[165]

[166] Equation 7

[167]

= Rm $ + Rwχ

[168]

[169] Since the eccentricity of the upper plate member 1440 is identical to that of the intermediate member 1450, the three line segments form an equilateral triangle. Accordingly, Eq. 8 can be obtained.

[170]

[171] Equation 8

[172]

R ₀ = 2Rco $ δ

[173]

[174] In this case, the angle δ is an angle subtended by a line segment from the origin O (ie, the center O of the lower base 1460 or the central axis 1413 of the lower base 1460) to the center O "of the upper plate member 1440 (ie, the optical axis 1411) and a line segment from the origin O to the center O 'of the intermediate member 1450 (ie, the central axis 1412 of the intermediate member 1450). Therefore, from a trigonometrical functional relation, the following inequality is obtained.

[175]

[176] Equation 9

[177]

R ₀ ≤ 2R

[178]

[179] Referring to FIG. 21, the angle δ is given by Eq. 10.

[180]

[183]

[184] On the other hand, azimuth angles satisfy the following equation.

[185]

[186] Equation 11

[188]

[189] Using Eqs. 4 through 6, the azimuth angle χcan be uniquely determined.

[190]

[191] Equation 12

[193] Accordingly, the rotation angle 0 of the intermediate member 1450 and the rotation angle χ of the upper plate member 1440 for aligning the optical axis 1411 on an arbitrary coordinate (x, y) can be uniquely determined using Eqs. 2 through 12.

[194] According to the third embodiment of the present invention, the eccentricity R of the upper plate member 1440 is preferably identical to the eccentricity R of the intermediate member 1450.In addition, if ordinary tolerance that occurs in assembling a camera board 1420, an image sensor 1422, and the lower base 1460 is D, then the ec-centricityR of the intermediate member 1450 and the upper plate member 1440 is preferably given by a half of that value. In other words, Eq. 13 can be obtained. [195]

[196] Equation 13

¹¹⁹⁷¹ _R = ^

2

[198] If R has a large value, then the optical axis 1411 can be located anywhere within a vast area. However, an adjustment range exceeding a normal tolerance range is not necessary. In addition, if the adjustment range is increased, then fine adjustment of the position of the optical axis 1411 becomes more difficult.

[199] Referring to FIG. 18, it is apparent that the radius of the intermediate through hole 1454 of the intermediate member 1450 should be larger than the radius of the lens coupling hole 1443 of the upper plate member 1440, and the size of the inner chamber 1464 of the lower base 1460 should be larger than the radius of the intermediate through hole 1454.

[200]

[201] Fourth Embodiment

[202] FIG. 22 is an exploded perspective view showing a C-mount (Cine Mount) or a CS- mount (Cine Short Mount) camera employing a lens holder according to a fourth embodiment (A4) of the present invention, and FIG. 23 is a longitudinal sectional view of a camera employing the lens holder according to the fourth embodiment of the present invention. Similar to the first embodiment, a rectangular coordinate system is used in order to easily understand the drawings. The Z-axis of the rectangular coordinate system coincides with the optical axis 1911 of a lens 1910, the Y-axis is parallel to one lateral side of a sensor plane 1924 of an image sensor, and the X-axis is parallel to another lateral side of the sensor plane 1924 that is perpendicular to the said one lateral side of the sensor plane 1924.

[203] A C-mount lens has a back flange of 17.526 mm, and a CS-mount lens has a back flange of 12.5 mm. Additionally, the lens coupling parts of C-mount and CS-mount lenses are provided as 1 inch male screws. Representative, for the simplicity of description, it is assumed that the present embodiment employs a CS-mount camera.

[204] Unlike the lens holders according to the first through the third embodiments of the present invention, the lens holder according to the fourth embodiment of the present invention includes an upper plate member 1940, an intermediate member 1950, a lower base 1960, and a rear cover 1990. according, it is closer to a camera case than a lens holder. Nevertheless, it will be referred to as a "lens holder" for the simplicity of description.

[205] The lower base 1960 is provided at an upper portion approximately with a lower end coupling part 1962 and at a lower portion approximately with a barrel part 1961. end coupling part 1962 has a rotationally symmetrical shape, and a lower base rail groove 1968 that is recessed in a V-shape is formed at the outer peripheral surface particular. Additional, a lower end through hole 1963 that is in a form of a cylindrical pipe is formed within the lower end coupling part 1962. Meanwhile, an inner chamber 1964 is provided within the barrel part 1961, and the outer peripheral surface of the barrel part 1961 may have a cylindrical shape or a rectangular box shape depending on applications. In addition, the rotational symmetry axis of the lower end coupling part 1962 passes through the center of the outer peripheral surface of the barrel part 1961 and the center of the inner chamber 1964. This common axis is the lower base central axis.

[206] The camera board 1920 is fixed to the lower base 1960 by using board fixing screws, and the camera board 1920 is inserted into the inner chamber 1964 of the lower base 1960. Board fixing screw coupling holes are formed in the inner chamber 1964 of the lower base 1960 on corresponding positions to the board through holes 1925 of the camera board 1920. Accordingly, an image sensor 1922 mounted on the camera board 1920 is inserted into the inner chamber 1964, and the central axis of the lower base 1960 substantially coincides with the center of the sensor plane 1924 of the image sensor 1922.

[207] Preferably, after the camera board 1920 is inserted into the inner chamber 1964 of the lower base 1960 and fixed tighten, the rear end of the lower base 1960 is preferably protected from dust and stray light by using a rear cover 1990. Rear cover fixing screw through holes 1995 are formed on the rear cover 1990, and rear cover fixing screw coupling holes are formed on the corresponding position of the barrel part 1961.Hence, the rear cover 1990 can be fixed to the barrel part 1961 by using rear cover fixing screws 1996, so that the image sensor is protected from dust or stray light, and the appearance of the camera is improved.

[208] The intermediate member 1950 is provided at an upper portion approximately with an intermediate coupling part 1952 and at a lower portion Julia with an intermediate receiving part 1951.In addition, an intermediate coupling hole 1953 having a shape of a cylindrical pipe is formed within the intermediate receiving part 1951, and an intermediate through hole 1954 having a shape of a cylindrical pipe is formed within the intermediate coupling part 1952.The intermediate receiving part 1951 is provided at the outer peripheral surface according with an intermediate handle 1955 to allow a user to be able to easily rotate it. It is desirable that the rotational symmetry axis of the intermediate coupling hole 1953, the rotational symmetry axis of the intermediate through hole 1954, and the central axis of the intermediate handle 1955 all coincide.

[209] The outer peripheral surface of the intermediate coupling part 1952 has a rotationally symmetrical shape having a rail groove 1958 recessed in a V-shape formed on it (see Fig. 23). The rotational symmetry axis of the outer peripheral surface of the intermediate coupling part is the central axis of the intermediate member 1950.However, the intermediate member central axis does not coincide with the rotational symmetry axis of the intermediate through hole 1954.In other words, the outer peripheral surface of the intermediate coupling part 1952 is eccentric to the intermediate through hole 1954.

[210] The shapes of the intermediate coupling hole 1953 and the intermediate through hole 1954 are cylindrical surfaces having a common rotational symmetry axis. As has been stated above, the rotational symmetry axis of the outer peripheral surface of the intermediate coupling part 1952 is the intermediate member central axis. According to the spirit of the present invention, although it is unnecessary that the central axis of the intermediate handle 1955 is coincident with the common rotational symmetry axis of the intermediate coupling hole 1953 and the intermediate through hole 1954, it is desirable if it does. The radius of the intermediate through hole 1954 is smaller than that of the intermediate coupling hole 1953.In other words, the intermediate coupling hole 1953 and the intermediate through hole 1954 of the intermediate member 1950 have a two-step structure, and a circular step is formed at the boundary between the intermediate coupling hole 1953 and the intermediate through hole 1954.

[211] The radius of the intermediate coupling hole 1953 is identical to the radius of the outer peripheral surface of the lower end coupling part 1962. Accordingly, the lower end coupling part 1962 is inserted into the intermediate coupling hole 1953 of the intermediate member 1950 , and the intermediate member can freely rotate full 360 relative to the lower base. Resultantly, the intermediate member central axis can freely rotate around the lower base central axis.

[212] Intermediate member fixing screw coupling holes 1956 are formed with a uniform interval on the outer peripheral surface of the intermediate receiving part 1951.The number of the intermediate member fixing screw coupling holes is preferably three. Accordingly, three intermediate member fixing screw coupling holes 1956 are formed with an interval of 120 along the outer peripheral surface.

[213] In a state where the intermediate member is combined with the lower base, the central axis 1957a of the intermediate member fixing screw 1957 passes slightly above the central axis 1968a of the lower base rail groove 1968. Referring to FIG. 23, when the intermediate member fixing screws 1957 are screwed into the intermediate member fixing screw coupling holes 1956, the intermediate member fixing screws 1957 prevent the lower end coupling part 1962 of the lower base 1960 from being separated from the intermediate receiving part 1951 of the intermediate member 1950.In this case, if the intermediate member fixing screws 1957 are loosened, the intermediate member 1950 can freely rotate with respect to the lower base 1960.On the other hand, if the in- termediate member fixing screws 1957 are fastened, the intermediate member fixing screws 1957 exert strong frictional force on the lower end coupling part 1962 of the lower base 1960, and the intermediate member 1950 is unable to rotate. Additional, since the central axis 1957a of an intermediate member fixing screw 1957 is positioned above the central axis 1968a of the lower base rail groove 1968 having a V shape, the intermediate member 1950 is pulled downward toward the lower base 1960 as the intermediate member fixing screws 1957 are fastened, and the intermediate member 1950 becomes unable to rotate with respect to the lower base 1960.

[214] The upper plate member 1940 is provided at an upper portion approximately with a plate member 1941 and at a lower portion Julia with an upper end coupling part 1942. An upper end coupling hole 1944 having a shape of a rotationally symmetrical cylinder is provided inside the upper end coupling part 1942.The radius of the upper end coupling hole 1944 is identical to that of the outer peripheral surface of the intermediate coupling part 1952.

[215] The plate member 1941 has a disc shape, and has a sufficiently large radius for completely covering the intermediate coupling hole 1953 of the intermediate member 1950, and a lens coupling hole 1943 is provided at an inner part brilliant. The lens coupling hole 1943 is a coupling unit where the lens coupling part 1916 of a lens 1910 is screwed into. Since the lens coupling part 1916 of a lens 1910, which is rotationally symmetrical about an optical axis 1911, is screwed into the lens coupling hole 1943 of the upper plate member 1940, the central axis of the lens coupling hole 1943 coincides with the optical axis 1911.This central axis of the lens coupling hole is the upper plate member central axis. The upper plate member central axis is eccentric to the rotational symmetry axis of the upper end coupling hole 1944 by a predetermined distance.

[216] An upper handle 1949 is formed through out the outer peripheral surfaces of the plate member 1941 and the upper end coupling part 1942.The shape of the upper handle 1949 is identical to that of the intermediate handle 1955. Lens fixing screw coupling hole 1945 is formed on the outer peripheral surface of the plate member 1941, and the lens fixing screw coupling hole 1945 penetrates from the outer peripheral surface of the plate member 1941 to the lens coupling hole 1943.In addition, upper plate member fixing screw coupling holes 1948 are formed on the outer peripheral surface of the upper end coupling part 1942.

[217] The lens holder according to the fourth embodiment A4 is different from the lens holder according to the third embodiment A3 in that the coupling part and the receiving part are inverted. Besides this, the operational mechanism is practically identical, and detailed description will be omitted in order to avoid redundancy.

[218]

[219] Fifth Embodiment [220] FIG. 24 is an exploded perspective view showing a lens holder according to the fifth embodiment (A5) of the present invention, and FIG. 25 is an assembled perspective view showing the lens holder, and FIG. 26 is an assembled sectional view of the lens holder. The lens holder according to the fifth embodiment of the present invention also includes an upper plate member 2140, an intermediate member 2150. and a lower base 2160. Similar to the first embodiment, a rectangular coordinate system is used so that those skilled in the art can easily comprehend the drawings. The Z-axis of the rectangular coordinate system coincides with the optical axis 2111 of a lens 2110, the Y-axis is parallel to one lateral side of the sensor plane of an image sensor, and the X- axis is parallel to another lateral side of the sensor plane that is perpendicular to the said one lateral side.

[221] The lower base 2160 is provided at an upper portion approximately with a lower end receiving part 2161 and at a lower portion Julia with a fixing part 2162.The lower end receiving part 2161 is provided at an inner part approximately with a lower end coupling hole 2163 having a cylindrical shape, and the fixing part 2162 is provided at an inner part apparent with a lower end through hole 2164 having a cylindrical shape. The rotational symmetry axis of the lower end coupling hole 2163 coincides with the rotational symmetry axis of the lower end through hole 2164. This common rotational symmetry axis is the lower base central axis 2113.

[222] The lower base 2160 is screwed into the barrel 2170 of a camera, and a barrel coupling part 2167 (see Fig. 26) is formed on the outer peripheral surface of the fixing part 2162 of the lower base 2160 corresponding to a lens coupling hole 2172 of the barrel 2170. The lens coupling hole 2172 of a camera barrel 2170 is usually provided as 1 inch female screw. According, the barrel coupling part 2167 is preferably provided as 1 inch male screw. A camera board (not shown in the drawing), where an image sensor is mounted on, is inserted into the camera barrel 2170 and fixed, similar to the fourth embodiment A4 of the present invention. The central axis 2113 of the lower base 2160 is perpendicular to the sensor plane of the image sensor, and the location of the central axis of the lower base substantially coincides with the center of the sensor plane of the image sensor.

[223] A lower handle 2165 is formed at the outer peripheral surface of the lower end receiving part 2161, and a plurality of holder fixing screw coupling holes 2166 are formed at the outer portion of the lower end coupling hole 2163. In addition, preferably , both the central axis of the lower handle 2165 and the central axis of the barrel coupling part 2167 formed at the outer peripheral surface of the fixing part 2162 coincide with the central axis 2113 of the lower base 2160.

[224] The intermediate member 2150 is provided at an upper portion approximately with an intermediate receiving part 2151 and at a lower portion approximately with an intermediate coupling part 2152.The outer peripheral surface of the intermediate coupling part 2152 has a shape of a rotationally symmetrical cylinder, and the radius of the outer peripheral surface is identical to the radius of the lower end coupling hole 2163 of the lower end receiving part 2161 .

[225] In addition, the intermediate member 2150 is provided at an inner part approximately with a cylindrical intermediate coupling hole 2153, and this intermediate coupling hole 2153 penetrates through the intermediate receiving part 2151 and the intermediate coupling part 2152.The rotational symmetry axis of the intermediate coupling hole 2153 is the intermediate member central axis 2112. The intermediate member central axis 2112 is eccentric to the rotational symmetry axis of the outer peripheral surface of the intermediate coupling part 2152 by a predetermined distance.

[226] An intermediate handle 2155 is formed at the outer peripheral surface of the intermediate receiving part 2151 so that it can be easily grasped and rotated by hand. The intermediate handle 2155 refers to protrusions formed in the Z- axis direction along the outer peripheral surface of the intermediate receiving part 2151. A multiple of intermediate arc-shaped holes 2154 are formed at the outer portion of the intermediate coupling hole 2153.

[227] As described above, the radius of the outer peripheral surface of the intermediate coupling part 2152 is identical to the radius of the lower end coupling hole 2163 formed within the lower end receiving part 2161. Therefore, the intermediate coupling part 2152 is inserted into the lower end coupling hole 2163 of the lower base 2160, and can be freely rotated full 360 ° around the rotational symmetry axis of the lower end coupling hole 2163.In this case, the intermediate member central axis 2112 rotates around the lower base central axis 2113.

[228] The upper plate member 2140 is provided at an upper portion approximately with a plate member 2141 and at a lower portion Julia with an upper end coupling part 2142.The outer peripheral surface of the upper end coupling part 2142 has a shape of a rotationally symmetricalcylinder, and the radius of the outer peripheral surface is identical to the radius of the intermediate coupling hole 2153 of the intermediate receiving part 2151.

[229] The upper plate member 2140 is provided at an inner part approximately with a lens coupling hole 2143 penetrating the upper plate member 2140 in the optical axis direction 2111.The lens coupling hole 2143 is a coupling unit where the lens coupling part 2116 of a lens 2110 is screwed into, and the optical axis 2111 of the lens 2110 screwed into the lens coupling hole 2143 coincides with the upper plate member central axis. The upper plate member central axis is eccentric to the rotational symmetry axis of the outer peripheral surface of the upper end coupling part 2142 by a predetermined distance. [230] The plate member 2141 has the shape of a disc completely covering the intermediate coupling hole 2153 of the intermediate member 2150.The plate member is formed at the outer peripheral surface specific with an upper handle 2144 and a lens fixing screw coupling hole 2146 .A plurality of upper end arc- shaped holes 2145 are formed at the outer portion of the lens coupling hole 2143.The shape of the upper handle 2144 is identical to that of the intermediate handle 2155.For the convenience of manipulation, the central axis of the upper handle 2144 is preferably coincident with the rotational symmetry axis of the outer peripheral surface of the upper end coupling part 2142.

[231] The upper plate member 2140, the intermediate member 2150, and the lower base

2160 are relatively fixed to each other by holder fixing screws 2180.The holder fixing screws 2180 are screwed into the holder fixing screw coupling holes 2166 after passing through the upper end arc-shaped hole 2145 of the upper plate member 2140 and the intermediate arc- shaped hole 2154 of the intermediate member 2150.In an absence of the holder fixing screws 2180, the intermediate member 2150 can freely rotate full 360 ° relative to the lower base 2160 about the lower base central axis 2113, and the upper plate member 2140 can freely rotate full 360 ° relative to the intermediate member 2150 about the intermediate member central axis 2112. according, similar to the third and the fourth embodiments of the present invention, the optical axis of a lens can be aligned at a particular position on the sensor plane of an image sensor. After the adjustment has been finished, the holder fixing screws 2180 are screwed into the holder fixing screw coupling holes 2166 after being passed through the upper end arc-shaped hole 2145 and the intermediate arc-shaped hole 2154.When these holder fixing screws are fastened , the upper plate member 2140, the intermediate member 2150, and the lower base 2160 are relatively fixed to each other, and maintain the aligned state.

[232] The lens holder according to the fifth embodiment of the present invention is characteristic in that the position of the optical axis 2111 of a lens 2110 that is combined into the lens coupling hole 2143 of a lens holder, which is combined into the lens coupling hole 2172 of a C-mount camera or a CS-mount camera, can be adjusted on the sensor plane of an image sensor that is installed within the camera barrel 2170. Since the operational mechanism of the lens holder is substantially identical to that of the fourth embodiment, detailed description will be omitted in order to avoid redundancy.

[233] Present, the assembling procedure and the operational mechanism of a lens holder according to the fifth embodiment of the present invention will be described. The barrel coupling part 2167 of the fixing part of the lower base 2160 is tightly screwed into the lens coupling hole 2172 of the camera barrel 2170. Meanwhile, the intermediate coupling part 2152 of the intermediate member 2150 is inserted into the lower end coupling hole 2163 of the lower base 2160, and subsequently, the upper end coupling part 2142 of the upper plate member 2140 is inserted into the intermediate coupling hole 2153 of the intermediate member 2150.Next, the holder fixing screws 2180 are passed through the upper end arc-shaped hole 2145 of the upper plate member 2140 and the intermediate arc-shaped hole 2154 of the intermediate member 2150, and then the lower end of the holder fixing screws 2180 are screwed into the holder fixing screw coupling holes 2166 of the lower base 2160.Thereafter, the lens coupling part 2116 of the lens 2110 is screwed into the lens coupling hole 2143 of the upper plate member 2140. Then, the camera is wired to a video monitor, and the lens is rotated either in clockwise or counterclockwise direction until clear focused image is obtained. Since the upper plate member central axis 2111 that is coincident with the optical axis of the lens 2110 is eccentric to the intermediate member central axis 2112, and the intermediate member central axis 2112 is eccentric to the lower base central axis 2113, the optical axis of the lens 2110 can be positioned at a specific point on the sensor plane of the image sensor by rotating the upper plate member 2140 and the intermediate member 2150 in appropriate directions. After the position of the optical axis of a lens, in other words, the center of the image plane, is adjusted by independently rotating the upper plate member and the intermediate member, the lens holder is securely fixed by fastening the holder fixing screws 2180.

[234]

[235] Sixth Embodiment

[236] Each embodiment of the present invention has been described exclusively in relation to lens holders for adjusting the position of an optical axis of a rotationally symmetrical lens, and the lens has been implicitly assumed as an imaging lens. However, the lens holders according to the embodiments of the present invention can be employed for non-imaging lenses. For example, the lens holder can be used to accurately adjust the position of a laser beam collimator. Further, these can be used to accurately adjust the central position of an object that is rotationally symmetrical about a central axis. In these cases, unlike the other embodiments of the present invention, it is unnecessary that the upper plate member, the intermediate member, and the lower base are perforated in the Z-axis direction corresponding to the direction of the optical axis of a lens.

[237] In order to use a lens holder according to an embodiment of the present invention as a stage apparatus, conditions simpler that those of a lens holder are required. The required conditions of a stage apparatus are as follows.

[238] The stage apparatus according to the sixth embodiment of the present invention is characterized in that the position of the rotational symmetry axis of a rotationally symmetrical object can be adjusted using the stage apparatus. The stage apparatus includes a lower base, an intermediate member, and an upper plate member. The upper plate member, the intermediate member, and the lower base have their respective central axes. The central axes of the upper plate member, the intermediate member, and the lower base are all parallel to each other.

[239] The upper plate member includes a coupling part that is coupled with an object such that the rotational symmetry axis of the object is coincident with the central axis of the upper plate member. The lower base includes a fixing part that can be fixed to one end of another object, where the said end is perpendicular to the central axis of the lower base. The intermediate member is coupled to the lower base in such a way that the intermediate member can freely rotate full 360 ° about the central axis of the lower base, and the upper plate member is coupled to the intermediate member in such a way that the upper plate member can freely rotate full 360 ° about the central axis of the intermediate member. The central axis of the intermediate member is eccentric to the central axis of the lower base by a predetermined distance, and the central axis of the upper plate member is eccentric to the central axis of the intermediate member by the predetermined distance.

[240] Although the present inventions have been described in relation to the exemplary embodiments of the present invention, it will be understood by one ordinary skilled in the art that various changes and modifications can be made without deviating from the spirit and the scope of the present invention, and such changes and modifications are also covered by the appended claims.

Claims

[1] A lens holder capable of adjusting a location of an optical axis of a lens, the lens holder comprising: a lower base; an intermediate member; an upper plate member; a first location adjusting unit; and a second location adjusting unit, wherein the lower base includes a fixing unit that is fixed to a camera board whereon an image sensor is mounted, the intermediate member is positioned between the upper plate member and the lower base, the upper plate member and the lower base are inserted into the intermediate member, the upper plate member includes a coupling unit that is coupled with the lens in such a way that the optical axis of the lens is aligned perpendicularly to a sensor plane of the image sensor, the upper plate member , the intermediate member, and the lower base are perforated in the direction of the optical axis of the lens coupled to the upper plate member, the first location adjusting unit exclusively moves the upper plate member in a Y-axis direction, which is perpendicular to the Z-axis direction, relative to the intermediate member, the Z-axis coincides with the optical axis of the lens, and the second location adjusting unit exclusively moves the intermediate member in an X-axis direction, which is perpendicular to both the Z -axis and Y-axis directions, relative to the lower base.

[2] The lens holder as claimed in claim 1, wherein the intermediate member has a shape of an open-ended pipe with a square cross-section having an insertion hole perforated in the Z-axis direction, the upper plate member includes a rectangular plate member that is formed at an upper side of the upper plate member to completely cover the insertion hole, a downward insertion part that is formed at a lower side of the upper plate member and inserted into the insertion hole of the intermediate member, and a lens coupling hole into which the lens having a rotationally symmetrical shape about the optical axis is screwed, a length of the downward insertion part in the Y-axis direction is shorter than a length of the downward insertion part in the X-axis direction, the lower base includes an upward insertion part that is formed at an upper side of the lower base and inserted into the insertion hole of the intermediate member, a fixing part formed at a lower side of the lower base and fixed to the camera board, and a rectangular inner chamber perforated in the Z-axis direction, and a length of the upward insertion part in the X-axis direction is shorter than a length of the upward insertion part in the Y-axis direction.

[3] The lens holder as claimed in claim 2, wherein a first outer through hole and a second outer through hole are formed at upper portions of both of the side surfaces of the intermediate member in the Y-axis direction, a third outer through hole and a fourth outer through hole are formed at lower portions of both of the side surfaces of the intermediate member in the X-axis direction, a first inner through hole and a second inner through hole corresponding to the first outer through hole and the second outer through hole of the intermediate member, respectively, are formed at both surfaces of the downward insertion part of the upper plate member in the Y-axis direction, a third inner through hole and a fourth inner through hole corresponding to the third outer through hole and the fourth outer through hole of the intermediate member, respectively, are formed at both surfaces of the upward insertion part of the lower base in the X-axis direction, the first location adjusting unit includes a first guide pin that is inserted into the first outer and the first inner through holes, and a first adjustment screw that is inserted into the second outer and the second inner through holes, the second location adjusting unit includes a second guide pin that is inserted into the third outer and the third inner through holes , and a second adjustment screw that is inserted into the fourth outer and the fourth inner through holes, a female screw corresponding to a thread of the first adjustment screw is formed in the second inner through hole of the upper plate member, a female screw corresponding to a thread of the second adjustment screw is formed in the fourth inner through hole of the lower base, and board fixing screw coupling holes are formed in a lower end of the fixing part.

[4] The lens holder as claimed in claim 2, further comprising a holder fixing unit that fixes the upper plate member, the intermediate member and the lower base relative to one another.

[5] A stage apparatus capable of adjusting a location of a rotational symmetry axis of an object having a rotationally symmetrical shape, the stage apparatus comprising: a lower base; an intermediate member; and an upper plate member, wherein the upper plate member, the intermediate member and the lower base have central axes, respectively, the central axes of the upper plate member, the intermediate member and the lower base are all parallel to each other, the upper plate member includes a coupling unit that is coupled with an object in such a way that the rotational symmetry axis of the object matches with the central axis of the upper plate member, the lower base includes a fixing unit that is fixed to an end of another object that is perpendicular to the lower base central axis, the intermediate member is combined with the lower base and freely rotatable for full 360 degrees with respect to the central axis of the lower base, the upper plate member is combined with the intermediate member and freely rotatable for full 360 degrees with respect to the central axis of the intermediate member, the central axis of the intermediate member is eccentric to the central axis of the lower base by a predetermined distance, and the central axis of the upper plate member is eccentric to the central axis of the intermediate member by the predetermined distance.

[6] A lens holder capable of adjusting a location of an optical axis of a lens, the lens holder comprising: a lower base; an intermediate member; and an upper plate member, wherein the upper plate member, the intermediate member and the lower base have central axes, respectively, the upper plate member central axis, the intermediate member central axis and the lower base central axis are all parallel to each other, the upper plate member includes a coupling unit that is coupled with the lens in such a way that the optical axis of the lens matches with the upper plate member central axis, the lower base includes a fixing unit that is fixed to a camera board whereon an image sensor is mounted, the intermediate member is combined with the lower base and freely rotatable for full 360 degrees with respect to the lower base central axis, the upper plate member is combined with the intermediate member and freely rotatable for full 360 degrees with respect to the intermediate member central axis, the intermediate member central axis is eccentric to the lower base central axis by a predetermined distance, the upper plate member central axis is eccentric to the intermediate member central axis by the predetermined distance, and the upper plate member, the intermediate member and the lower base are perforated in the optical axis direction.

[7] The lens holder as claimed in claim 6, wherein the lower base includes a lower end receiving part formed at an upper side of the lower base and a fixing part formed at a lower side of the lower base, the lower end receiving part has a rotationally symmetrical shape about the lower base central axis, a lower end coupling hole having a cylindrical shape is formed within the lower end receiving part, a rectangular inner chamber perforated in the direction of the lower base central axis is formed within the fixing part , the lower base central axis passes through a center of the rectangular inner chamber, lower base fixing screw coupling holes are formed on an outer peripheral surface of the lower end receiving part, and board fixing screw coupling holes are formed on a lower end of the fixing part.

[8] The lens holder as claimed in claim 7, wherein the intermediate member includes an intermediate receiving part formed at an upper side of the intermediate member and an intermediate coupling part formed at a lower side of the intermediate member, an outer peripheral surface of the intermediate coupling part has a rotationally symmetrical shape and is formed with an intermediate member rail groove having a V-shape, the outer peripheral surface of the intermediate coupling part has a radius identical to a radius of the lower end coupling hole formed within the lower end receiving part, the intermediate member central axis is eccentric to a rotational symmetry axis of the outer peripheral surface of the intermediate coupling part by a predetermined distance, an intermediate through hole having a cylindrical shape and rotationally symmetrical about the intermediate member central axis is formed within the in- termediate coupling part, an intermediate coupling hole having a cylindrical shape and rotationally symmetrical about the intermediate member central axis is formed within the intermediate receiving part, and an intermediate handle and intermediate member fixing screw coupling holes are formed on an outer peripheral surface of the intermediate receiving part.

[9] The lens holder as claimed in claim 8, wherein the upper plate member includes a plate member formed at an upper side of the upper plate member and an upper end coupling part formed at a lower side of the upper plate member, an outer peripheral surface of the upper end coupling part has a rotationally symmetrical shape and is formed with an upper plate rail groove having a V-shape, the outer peripheral surface of the upper end coupling part has a radius identical to a radius of the intermediate coupling hole formed within the intermediate receiving part, the upper plate member central axis is eccentric to a rotational symmetry axis of the outer peripheral surface of the upper end coupling part by a predetermined distance, the plate member has a disc shape that completely covers the intermediate coupling hole of the intermediate member, a lens coupling hole is formed within the upper plate member in a direction of the optical axis, the lens coupling hole is a coupling unit into which a lens coupling part of the lens is screwed, the optical axis of the lens coupled to the lens coupling hole coincides with the upper plate member central axis, and an upper handle and a lens fixing screw coupling hole are formed on an outer peripheral surface of the plate member.

[10] The lens holder as claimed in claim 6, wherein the lower base includes a lower end coupling part formed at an upper side of the lower base and a barrel part formed at a lower side of the lower base, the lower end coupling part has a rotationally symmetrical shape about the lower base central axis, a lower end through hole having a cylindrical shape is formed within the lower end coupling part, a lower base rail groove having a V-shape is formed on an outer peripheral surface of the lower end coupling part, a central axis of the barrel part coincides with the lower base central axis, an inner chamber is formed within the barrel part, and board fixing screw coupling holes that are coupled to the camera board are formed in the inner chamber.

[11] The lens holder as claimed in claim 10, wherein the intermediate member includes an intermediate coupling part formed at an upper side of the intermediate member and an intermediate receiving part formed at a lower side of the intermediate member, an intermediate coupling hole having a shape of a rotationally symmetrical cylinder is formed within the intermediate receiving part, the intermediate coupling hole has a radius that is identical to a radius of the outer peripheral surface of the lower end coupling part, the intermediate member central axis is eccentric to a rotational symmetry axis of the intermediate coupling hole by a predetermined distance, an intermediate through hole having a cylindrical shape and rotationally symmetrical about the rotational symmetry axis of the intermediate coupling hole is formed within the intermediate coupling part, an outer peripheral surface of the intermediate coupling part has a rotationally symmetrical shape about the intermediate member central axis, an intermediate member rail groove having a V-shape is formed on the outer peripheral surface of the intermediate coupling part, and an intermediate handle and intermediate member fixing screw coupling holes are formed on an outer peripheral surface of the intermediate receiving part.

[12] The lens holder as claimed in claim 11, wherein the upper plate member includes a plate member formed at an upper side of the upper plate member and an upper end coupling part formed at a lower side of the upper plate member, an upper end coupling hole having a rotationally symmetrical cylindrical shape is formed within the upper end coupling part, the upper end coupling hole has a radius that is identical to a radius of the outer peripheral surface of the intermediate coupling part, the upper plate member central axis is eccentric to a rotational symmetry axis of the upper end coupling hole by a predetermined distance, a lens coupling hole is formed within the plate member, the lens coupling hole is a coupling unit into which a lens coupling part of the lens is screwed, the optical axis of the lens coupled to the lens coupling hole coincides with the upper plate member central axis, an upper handle is formed through out an outer peripheral surface of the plate member and an outer peripheral surface of the upper end coupling part, upper plate member fixing screw coupling holes are formed on the outer peripheral surface of the upper end coupling part, and a lens fixing screw coupling hole is formed on the outer peripheral surface of the plate member.

[13] The lens holder as claimed in claim 6, wherein the lower base includes a lower end receiving part formed at an upper side of the lower base and a fixing part formed at a lower side of the lower base, a lower end coupling hole having a cylindrical shape and rotationally symmetrical about the lower base central axis is formed within the lower end receiving part, a lower handle is formed at an outer peripheral surface of the lower end receiving part, holder fixing screw coupling holes are formed outside the lower end A coupling hole, a lower end through hole having a cylindrical shape and rotationally symmetrical about the lower base central axis is formed within the fixing part, and a barrel coupling part is formed on an outer peripheral surface of the fixing part.

[14] The lens holder as claimed in claim 13, wherein the intermediate member includes an intermediate receiving part formed at an upper side of the intermediate member and an intermediate coupling part formed at a lower side of the intermediate member, an outer peripheral surface of the intermediate coupling part has a shape of a rotationally symmetrical cylinder, the outer peripheral surface of the intermediate coupling part has a radius that is identical to a radius of the lower end coupling hole of the lower end receiving part, the intermediate member central axis is eccentric to a rotational symmetry axis of the outer peripheral surface of the intermediate coupling part by a predetermined distance, an intermediate coupling hole penetrating through the intermediate receiving part and the intermediate coupling part is formed within the intermediate member, the intermediate coupling hole has a cylindrical shape and is rotationally symmetrical about the intermediate member central axis, an intermediate handle is formed on an outer peripheral surface of the intermediate receiving part, and a plurality of intermediate arc-shaped holes are formed outside the intermediate coupling hole. [15] The lens holder as claimed in claim 14, wherein the upper plate member includes a plate member formed at an upper side of the upper plate member and an upper end coupling part formed at a lower side of the upper plate member, an outer peripheral surface of the upper end coupling part has a shape of a rotationally symmetrical cylinder, the outer peripheral surface of the upper end coupling part has a radius that is identical to a radius of the intermediate coupling hole of the intermediate receiving part, the upper plate member central axis is eccentric to a rotational symmetry axis of the outer peripheral surface of the upper end coupling part by a predetermined distance, a lens coupling hole is formed within the upper plate member that penetrates the upper plate member in a direction of the optical axis, the lens coupling hole is a coupling unit into which a lens coupling part of the lens is screwed, the optical axis of the lens coupled to the lens coupling hole coincides with the upper plate member central axis, the plate member has a disc shape that completely covers the intermediate coupling hole of the intermediate member, an upper handle and a lens fixing screw coupling hole are formed on an outer peripheral surface of the plate member, and a plurality of upper end arc-shaped holes are formed outside the lens coupling hole.