WO2009061132A1

WO2009061132A1 - Guidance apparatus for focusing on iris and method for the same

Info

Publication number: WO2009061132A1
Application number: PCT/KR2008/006531
Authority: WO
Inventors: Won-Kyoung Kim
Original assignee: Rehoboth Tech Co., Ltd.
Priority date: 2007-11-08
Filing date: 2008-11-06
Publication date: 2009-05-14
Also published as: KR20090047840A; KR100900263B1

Abstract

Disclosed are a guidance apparatus and method for focusing on iris. The guide apparatus for focusing on iris includes: a slit member in which at least one slit is formed; a light source illuminating light on the slit member; a magnification lens magnifying a slit image generated when the light passes through the slit member; a diaphragm disposed around the magnification lens and creating a diaphragm image; and a prism transferring the slit image and the diaphragm image to a user's eye so that the user adjusts a position of his or her eye to a focus position at which the user's iris is focused, in such a manner as to match an edge of the slit image to an edge of the diaphragm image, and transferring an iris image reflected from the user's iris to the image sensor.

Description

GUIDANCE APPARATUS FOR FOCUSING ON IRIS AND

METHOD FOR THE SAME

Technical Field

[1] The present invention relates to a guidance apparatus and method for focusing on iris to acquire an iris image, in an iris recognition system for identifying an individual using information about iris having different patterns for each individual. Background Art

[2] In general, an iris recognition system is a security system which has appeared following a fingerprint recognition system. The iris recognition system has been developed by applying information about iris having different patterns for each individual to an authentication technology for security.

[3] The iris recognition system has advantages of accurately identifying even people wearing glasses or contact lenses, and causing no aversion as it is a contactless type. The iris recognition system is being applied to various applications including entrance control, time & attendance management, integrated building management system, Automatic Teller Machines (ATM), computer security, electronic commerce assurance services, airport information systems, etc.

[4] The operational concept of the iris recognition system is as follows. First, when a user moves the position of his or her eye to a position where an iris image is acquired, an iris camera captures the user's iris and creates an iris image. Then, an iris recognition algorithm analyzes the iris pattern of the iris image for each region, and generates a user's unique iris code. Finally, the iris recognition algorithm searches a database for the same code as the user's unique iris code, thereby carrying out user identification.

[5] Meanwhile, the iris recognition system may include a focus distance adjusting unit for focusing on the user's iris as the user may move the position of the eye to an improper position. For example, the iris camera includes a distance sensor for measuring the distance from the user's iris to the camera lens, and an actuator for moving an image lens on the basis of the distance value measured by the distance sensor to adjust a focus distance.

[6] However, in this case, due to the installation of the distance sensor and actuator, the iris recognition system has a complicated structure. Also, when the focus distance is adjusted, the center of the iris may be deviated from the optical axis of the image lens depending on the location on which the user fixes the eye, which makes the creation of an accurate iris image difficult. Furthermore, the actuator makes noise as it operates, which may make the user displeased. Disclosure of Invention

Technical Problem

[7] Accordingly, disclosed are a guidance apparatus for focusing on iris to acquire an accurate iris image, which can obtain a wide iris region, make no noise, and have a simple structure, and a method for operating the guidance apparatus. Technical Solution

[8] According to an aspect of the present invention, there is provided a guidance apparatus for focusing on iris, including: a slit member in which at least one slit is formed; a light source illuminating light on the slit member; a magnification lens magnifying a slit image generated when the light passes through the slit member; a diaphragm disposed around the magnification lens and creating a diaphragm image; and a prism transferring the slit image and the diaphragm image to a user's eye so that the user adjusts a position of his or her eye to a focus position at which the user's iris is focused, in such a manner as to match an edge of the slit image to an edge of the diaphragm image, and transferring an iris image reflected from the user's iris to the image sensor.

[9] According to another aspect of the present invention, there is provided a guidance method for focusing on iris, including: creating a slit image by illuminating light on a slit member in which at least one slit is formed; magnifying the slit image using the magnification lens; transferring the magnified slit image and a diaphragm image created by a diaphragm image disposed around the magnification lens, to a user's eye, via a prism; and allowing the user to adjust a position of his or her eye to a focus position at which the user's iris is focused, in such a manner as to match an edge of the slit image to an edge of the diaphragm image while viewing the slit image and the diaphragm image together.

Advantageous Effects

[10] Therefore, since the guidance apparatus and method according to the present invention guide a user to move the position of his or her iris to a focus position and match the center of the iris to the optical axis of an image sensor, an accurate iris image can be acquired, which contributes to correct user identification of an iris identification system.

[11] Also, since the guidance apparatus according to the present invention does not need a distance sensor and actuator additionally as it needs not to move an image lens, there are advantages of simplicity in construction and noise suppression. Brief Description of the Drawings

[12] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[13] FIG. 1 shows the construction of a guidance apparatus for focusing on iris, according to an embodiment.

[14] FIG. 2 shows a slit member according to an embodiment.

[15] FIG. 3 illustrates a slit image and diaphragm image viewed by a user.

[16] FIG. 4 is a view for explaining operation of the iris guidance apparatus illustrated in

FIG. 1 when a user moves the position of his or her eye to a focus position to focus on the user's iris.

[17] FIG. 5 illustrates an image viewed by a user when the edge of the slit image is matched to the edge of the diaphragm image. Mode for the Invention

[18] The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numbers in the drawings denote like elements.

[19] FIG. 1 shows the construction of a guidance apparatus 100 for focusing on iris, according to an embodiment.

[20] Referring to FIG. 1, the guidance apparatus 100, which is installed in an iris recognition system, guides a user to move the position of his or her eye to a position at which the user's iris is focused in order to acquire an iris image, and includes a light source 110, a slit member 120, a magnification lens 130, a diaphragm 140, and a prism 150.

[21] The light source 110 illuminates light on the slit member 120 in which a plurality of slits 121 are formed, while passing the light through the slits 121. Also, the light source 110 acts to widen the iris region maximally when the iris image is acquired.

[22] That is, the light illuminated from the light source 110 passes through the slits 121 of the slit member 120, and creates a slit image 124 illustrated in FIG. 3. The slit image 124 is transferred to the user's eye, and light forming the slit image 124 illustrates the user's eye. Due to the light illuminated on the user's eye, the user's pupil is contracted and the iris region is widened. The light source 110 may be a light emitting diode which illuminates visible light. [23] The slit member 120 creates the slit image 124 by passing the light illuminated from the light source 110 through the slits 121. The slits 121 may be in various shapes.

[24] For example, the slit member 120, as illustrated in FIG. 2, has a circle-shaped slit 122 in the center and a ring-shaped slit 123 around the circle-shaped slit 122. In this case, the slit member 120 may be a multi-layered structure of an opaque base layer and a transparent layer, wherein the circle-shaped slit 122 and the ring-shaped slit 123 are formed in the base layer and the transparent layer covers a side of the base layer.

[25] The slit image 124 includes a ring-shaped slit image 124a formed by the ring-shaped slit 123, and a circle-shaped slit image 124b formed by the circle-shaped slit 122, as illustrated in FIG. 3.

[26] The slit image 124 is transferred to the user's eye by the prism 150 which will be described later. The viewed size of the slit image 124 depends on the distance from the user's eye to the prism 150. Here, the ring-shaped slit image 124a guides the user to move the position of his or her eye 1 to a focus position at which the user's iris is focused.

[27] For example, the case of setting the focus position to a position at which the edge of the ring-shaped slit image 124a is matched to the edge of a circle-shaped diaphragm image 141 which will be described later will be described below.

[28] When the user adjusts the position of the eye, while viewing the ring-shaped slit image 124a and diaphragm image 141, so that the edge of the ring-shaped slit image 124a is matched to the edge of the diaphragm image 141 (see FIGS. 4 and 5), the user's iris can be focused at the adjusted position.

[29] The circle-shaped slit image 124b guides the user to easily match the center point of the iris to the optical axis. That is, when the user adjusts the position of the eye so that the edge of the ring-shaped slit image 124a is matched to the edge of the diaphragm image 141, while viewing both the circle-shaped slit image 124b and ring-shaped slit image 124a, the user can fix the eye on the circle-shaped slit image 124a. Accordingly, the user can easily match the center of the iris to the optical axis.

[30] The magnification lens 130 magnifies the slit image 124 formed by light passing through the slits 122 and 123 of the slit member 120 so that the user can view the slit image 124. By magnifying the slit image 124 and transferring the magnified slit image 124 to the user's eye 1, a reduction of the distance between the light source 110 and prism 150 is possible. The installation of the magnification lens 130 is effective in constructing a compact iris guidance apparatus and in providing a uniform slit image. Here, the optical axis of the magnification lens 130 is aligned with the center of the slit member 120.

[31] The diaphragm 140 is disposed around the magnification lens 130 and creates the diaphragm image 141. The diaphragm image 141 is transferred to the user's eye by the prism 150, together with the slit image 124. The diaphragm image 141 acts to inform the user of whether his or her eye is in the focus position where the iris is focused, while the edge of the ring-shaped slit image 124a moves from the position illustrated in FIG. 3 to the position illustrated in FIG. 5 depending on the position of the eye.

[32] The diaphragm 140 creates the diaphragm image 141 in a circle shape in correspondence to the ring-shaped slit image 124a. In order to create the circle- shaped diaphragm image 141, the diaphragm 140 has a circle-shaped hole in the center, and the center point of the diaphragm 140 is positioned on the center axis of the magnification lens 130.

[33] Also, the diaphragm 140 is configured so that the user's iris is focused when the edge of the circle-shaped diaphragm 141 is matched to the edge of the ring-shaped image 124a. Accordingly, the user adjusts the position of his or her eye, while viewing the ring-shaped slit image 124a and diaphragm image 141 together, and recognizes that the eye is positioned at the focus position where the iris is focused, when the edge of the ring-shaped image 124a is matched to the edge of the circle-shaped diaphragm 141.

[34] The prism 150 transfers the slit image 124 and diaphragm image 141 to the user's eye

1, in order to allow the user to move the eye to the focus position at which the iris is focused. Also, the prism 150 transfers an iris image reflected from the user's iris to an image sensor 10.

[35] The prism 150 can include a reflective mirror 151 and an infrared filter 152. The reflective mirror 151 reflects the slit image 124 and diaphragm image 141 to the user's eye, and reflects the iris image reflected from the user's iris to the image sensor 10. Accordingly, the reflective mirror 151 can be configured to reflect and transmit light. Here, the transmittance of the reflective mirror 151 can be set to about 50%.

[36] Also, the reflective mirror 151 transmits a part of the slit image 124 and diaphragm image 141 to the infrared filter 152, and reflects a part of the slit image 124 and diaphragm image 141 in a visible wavelength region reflected from the infrared filter 152 to the user's eye. Also, the reflective mirror 151 reflects iris images reflected from the user's iris to the image sensor 10.

[37] When the iris images reflected from the user's iris are reflected by the reflective mirror 151 and then incident to the infrared filter 152, the infrared filter 152 transmits only iris images in an infrared wavelength region among the received iris images to the image sensor 10. The infrared filter 152 reflects the part of the slit image 124 and diaphragm image 141 transmitted through the reflective mirror 151, to the reflective mirror 151, and the reflected image is transferred to the user's eye, as described above.

[38] The iris image transmitting through the infrared filter 152 is provided to the image sensor 10 via the image lens 11. Here, the image lens 11 acts to collect light forming the iris image and transfer the iris image again to the user's eye. The image sensor 10 may be a charge-coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor. The iris image acquired by the image sensor 10 may be input to an iris identification algorithm.

[39] Now, an exemplary method of focusing on a user's iris will be described below.

[40] First, an iris recognition algorithm detects the presence of a user's eye on the basis of an image acquired from the image sensor 10. If the presence of a user's eye is detected, the iris recognition algorithm illuminates light from the light source 110 to the slit member 120, thus creating a slit image 124.

[41] Then, the slit image 124 is magnified by the magnification lens 130, and then as illustrated in FIG. 3, and the magnified slit image 124 and a diaphragm image 141 created by the diaphragm 140 disposed around the magnification lens 130 are transferred to the user's eye via the prism 150.

[42] That is, the slit image 124 and diaphragm image 141 are transferred to the reflective mirror 151, and then a part of the slit image 124 and diaphragm image 141 is transferred to the infrared filter 152 via the reflective mirror 151. Then, the part of the slit image 124 and diaphragm image 141 in a visible light wavelength, transferred to the infrared filter 152, is reflected by the infrared filter 152, and then incident to the user's eye 1 via the reflective mirror 151.

[43] Accordingly, the user adjusts the position of his or her eye, while viewing the slit image 124 and diaphragm image 141 transferred to the user's eye 1, so that the edge of the slit image 124 is matched to the edge of the diaphragm image 141.

[44] In detail, the user can adjust the position of the eye while viewing the circle-shaped slit image 124b and the ring-shaped slit image 124a together so that the edge of the ring-shaped slit image 124a is matched to the edge of the diaphragm image 141, as illustrated in FIG. 5. During this process, the center point of the user's iris can be easily matched to the optical axis. Also, if it is set that the user's iris is focused at the position where the edge of the slit image 124 is matched to the edge of the diaphragm image 141, the user's iris can be easily guided to a focus position. Accordingly, an accurate iris image can be acquired, and accurate user identification of an iris recognition system is possible.

[45] According to the current embodiment, since a distance sensor and actuator are not needed additionally to focus on iris, and the image lens needs not to move, there are advantages of simplicity in construction and noise suppression.

[46] Meanwhile, while the user adjusts the position of his or her eye, iris images reflected from the user's iris are transferred to the infrared filter 152 via the reflective mirror 151, and the infrared filter 152 transmits only iris images in an infrared wavelength region among the iris images to the image sensor 10.

[47] Then, the iris recognition algorithm selects an iris image in which the user iris is focused, from among the iris images in the infrared light wavelength region, while the user adjusts the position of his or her eye. Then, the iris recognition algorithm analyzes the iris pattern of the selected iris image for each region, and generates the user's unique iris code. Finally, the iris recognition algorithm searches a database for the same code as the user's unique iris code.

[48] It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Industrial Applicability

[49] As described above, the present invention can be applied to an iris recognition system requiring iris focusing to acquire an iris image.

Claims

[1] A guidance apparatus for focusing on iris, comprising: a slit member in which at least one slit is formed; a light source illuminating light on the slit member; a magnification lens magnifying a slit image generated when the light passes through the slit member; a diaphragm disposed around the magnification lens and creating a diaphragm image; and a prism transferring the slit image and the diaphragm image to a user's eye so that the user adjusts a position of his or her eye to a focus position at which the user's iris is focused, in such a manner as to match an edge of the slit image to an edge of the diaphragm image, and transferring an iris image reflected from the user's iris to the image sensor. [2] The apparatus of claim 1, wherein the slit member has a circle-shaped slit in a center portion of the slit member, and a ring-shaped slit formed around the circle- shaped slit. [3] The apparatus of claim 1, wherein the prism comprises: reflective mirror reflecting the slit image and the diaphragm image to the user's eye, and reflecting the iris image reflected from the user's iris to the image sensor; and an infrared filter transferring a part of the slit image and the diaphragm image transmitted through the reflective mirror to the user's eye via the reflective mirror, and transmitting only an iris image in an infrared wavelength region, among iris images reflected by the reflective mirror from the user eye, to the image sensor. [4] A guidance method for focusing on iris, comprising: creating a slit image by illuminating light on a slit member in which at least one slit is formed; magnifying the slit image using the magnification lens; transferring the magnified slit image and a diaphragm image created by a diaphragm image disposed around the magnification lens, to a user's eye, via a prism; and allowing the user to adjust a position of his or her eye to a focus position at which the user's iris is focused, in such a manner as to match an edge of the slit image to an edge of the diaphragm image while viewing the slit image and the diaphragm image together.