WO1996015921A1

WO1996015921A1 - Rearview mirror system for vehicles

Info

Publication number: WO1996015921A1
Application number: PCT/KR1995/000152
Authority: WO
Inventors: Koo Ko
Original assignee: Koo Ko
Priority date: 1994-11-22
Filing date: 1995-11-21
Publication date: 1996-05-30

Abstract

An improved rearview mirror system for vehicles is disclosed. In the above mirror system, a movable lens unit (V) is mounted to the rear portion of the vehicle, while either a paraboloidal or ellipsoidal reflector (M) is mounted to the front portion of the vehicle. The paraboloidal and ellipsoidal reflectors (M) have a paraboloid of revolution and an ellipsoid of revolution, respectively. The mirror system reflects the traffic conditions behind the vehicle without any distortions of the image, thus giving a good rear view to the driver. The mirror system allows the driver to have a wide rear view, which can be expected when the driver directly views the traffic conditions behind the vehicle through the rear windshield. The mirror system also gives the wide rear view to the driver regardless of passengers sitting in the back seats, thereby allowing the driver to drive the vehicle more safely.

Description

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REARVIEW MIRROR SYSTEM FOR VEHICLES

Technical Field

The present invention relates in general to a rearview mirror system for vehicles and, more particularly, to a structural improvement in such a rearview mirror system for giving a wider rear view to drivers-

Background Art

As well known to those skilled in the art, vehicles are typically provided with a plurality of accessaries for making driving more convenient and safer for the driver.

For example, a vehicle is typically equipped with various types of reflection mirrors for allowing the driver to view the traffic conditions behind the vehicle while driving. The above reflection mirrors equipped in the vehicle include a rearview mirror mounted to the upper front center inside the vehicle's cabin. The above rearview mirror is also known as "room mirror". The reflection mirrors also include a pair of sideview mirrors which are mounted to both sides of the car body.

However, it has been noted that the typical rearview mirror mounted to the upper front center inside the cabin doesn't give a wide rear view to the driver due to both the positional limit of the rearview mirror and the structural limit of the car body. In this regard, the typical rearview mirror sometimes fails to allow the driver to drive the vehicle safely. That is, the above typical rearview mirror only gives a limited rear view to the driver as traffic conditions behind the vehicle are partially intercepted by the car body when they are reflected by the rearview mirror. That is, both the rear windshield support frame and trunk of the car body partially intercept the light originating from the traffic conditions behind the vehicle. It has been noted that the field of the rear view provided by the above rearview mirror is limited to the upper and lower angles of about 10^* and left and right angles of about 30^*. In addition, the field of the rear view provided by the above rearview mirror will be further reduced when at least one passenger sits in the back seats of the vehicle and partially intercepts the field of the rear view. In this regard, the typical rearview mirror mounted to the front center inside the cabin fails to prevent dead angle traffic accidents while driving. That is, the above rearview mirror cannot allow the driver to see the dead spaces about the rear side corners and just below the back of the car body. The above rearview mirror thus often fails to prevent the dead angle traffic accidents while passing, backing up or changing lanes.

In an effort to rectify the above problems, Japanese U.M. Laid-open Publication No. Sho. 47-18333 (laid-open published on June 24, 1972) discloses a somewhat improved rearview mirror system. The above Japanese rearview mirror system intends to remove the dead spaces. In order to achieve the above object, a front convex mirror is mounted to the upper front center of the vehicle's cabin. In addition, a rear convex mirror and a flat mirror are mounted to the rear upper portion of the cabin. The rear convex mirror and the flat mirror are arrayed to diagonally face each other. However, as the above rear convex and flat mirrors diagonally face each other at the rear upper portion of the cabin as described above, the image thrown on the front convex mirror is distorted and thereby fails to provide a good image. That is, the image thrown on the mirror is vertically reduced and flattened. In addition, it is almost impossible to expect the desired image throwing effect when using a conventional convex mirror in the above Japanese system. Hence, the above Japanese mirror system still causes several problems thereby being scarcely used.

Disclosure of Invention

It is, therefore, an object of the present invention to provide an improved rearview mirror system for vehicles in which the above problems can be overcome and which reflects the traffic conditions behind the vehicle without any distortions of the image thrown on the mirror, thus giving a good rear view to the driver while driving. The above rearview mirror system allows the driver to have a wider rear view, which can be expected when the driver directly views the traffic conditions behind the vehicle through the rear windshield, and remarkably reduces the dead spaces. The above rearview mirror system also continuously gives a wider rear view to the driver regardless of passengers sitting in the back seats, thereby allowing the driver to drive the vehicle more safely.

In order to achieve the above, an embodiment of the present invention provides a rearview mirror system for vehicles comprising a lens means mounted to an upper portion of a rear windshield of a vehicle and adapted for transmitting light which originates from behind the vehicle, and a front reflection means mounted to a front upper portion of the vehicle ahead of a driver and adapted for reflecting the light to produce an image, wherein the front reflection means comprises a paraboloidal reflector having a paraboloidal reflection surface. The paraboloidal reflection surface is a part of a paraboloid of revolution directed to the driver. The paraboloid of revolution is produced by assuming the direction of a driver's forward vision to be a negative directional Y- axis, assuming a transverse direction of the vehicle ahead of the driver to be an X-axis, setting the center of an assumed reflection plane for reflecting the light and producing the image ahead of the driver, drawing a curve of a quadratic function Y=-AX² passing the center of the assumed reflection surface to draw a parabola, and rotating the parabola about the Y-axis to form the paraboloid of revolution.

In accordance with another embodiment of the invention, the front reflection means comprises an ellipsoidal reflector having an ellipsoidal reflection surface. The above ellipsoidal reflection surface is a part of an ellipsoid of revolution directed to the driver. The ellipsoid of revolution is produced by setting an assumed reflection plane for reflecting the light and producing the image ahead of the driver, setting the size and position of the reflection plane, setting the size and position of a light transmitting portion of said lens means, assuming a fixed point, onto which light originating from another fixed point corresponding to a driver's eye is focused after being reflected by the assumed reflection plane and passing the lens means is focused, to be a first focus point, assuming the other fixed point corresponding to the driver's eye to be a second focus point, drawing an ellipse having the first and second focus point as its fixed points , and rotating the ellipse about a straight line passing the first and second focus points to form the ellipsoid of revolution. Brief Description of Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a side view of a vehicle equipped with a rearview mirror system in accordance with the present invention, showing the operation of the mirror system;

Figs. 2A and 2B are sectional views of a lens unit of the rearview mirror system of this invention, in which:

Fig. 2A shows the lens unit giving the relatively narrower field of the rear view; and

Fig. 2B shows the lens unit giving the relatively wider field of the rear view; Figs. 3A and 3B are views showing a paraboloidal reflector used as a front reflection unit of the rearview mirror system in accordance with an embodiment of this invention, in which:

Fig. 3A is a graphic diagram showing the method for producing the paraboloid of revolution of the paraboloidal reflector; and

Fig. 3B is a perspective view of the resulting paraboloidal reflector;

Fig. 4 is a view showing the construction of a means for driving a movable lens of the lens unit of Fig. 2;

Figs. 5A to 5C are views showing the operation for adjusting the vertical viewing angle of the above lens unit of Fig. 2, in which:

Fig. 5A is a side view of the vehicle equipped with the rearview mirror system of the present invention provided with the above lens unit;

Fig. 5B is a sectional view showing the operation for vertically turning the lens unit; and

Fig. 5C is a view showing the drive mechanism for vertically turning the lens unit; Fig. 6 is a plan view of the vehicle equipped with the rearview mirror system of the present invention, showing the operation of the rearview mirror system;

Figs. 7A to 7C are views showing lens units in accordance with other embodiments of the present invention, in which:

Fig. 7A is a view of the lens unit using a diverging lens;

Fig. 7B is a view of the lens unit using a Fresnel lens; and Fig. 7C is a sectional view of the Fresnel lens used in the lens unit of Fig. 7B;

Figs. 8A and 8B are views showing an ellipsoidal reflector used as the front reflection unit of the rearview mirror system in accordance with another embodiment of the present invention, in which:

Fig. 8A is a graphic diagram showing the method for producing the ellipsoid of revolution of the above ellipsoidal reflector; and

Fig. 8B is a perspective view of the resulting ellipsoidal reflector.

Best Mode for Carrying out the Invention

Fig. 1 is a side view of a vehicle equipped with a rearview mirror system of this invention. Figs. 2A and 2B are views of a lens unit of the above rearview mirror system. Figs. 3A and 3B are views of a paraboloidal reflector used as a front reflection unit of the above rearview mirror system in accordance with an embodiment of the invention. As shown in the drawings, the rearview mirror system of the present invention includes a lens unit V which is mounted to the upper portion of the rear windshield of the car body. The lens unit V transmits light originating from behind the vehicle. The rearview mirror system also includes a front reflection unit M which is mounted to the front upper portion inside the cabin. The light originating from the traffic conditions behind the vehicle pass the lens unit V and in turn produce an image on the front reflection unit M. In order to form the above paraboloidal reflector used as the above front reflection unit M, X and Y-axes are drawn such that those axes cross each other at a right angle, thereby forming a graph with X and Y-axes. That is, the direction of the driver's forward vision is assumed to be a negative 921 PC-- -

directional Y-axis, while the transverse direction of the car body ahead of the driver F is assumed to be an X-axis, thereby forming the graph as shown in Fig. 3A. Thereafter, the center C of an assumed reflection plane is pointed in the graph. The light passing the lens unit V will be reflected by the assumed reflection plane, thereby producing the image on that reflection plane ahead of the driver F. After pointing the center C of the reflection plane in the graph, a curve of a quadratic function Y=AX⁴ is drawn in the graph to pass the center C of the reflection plane, thereby drawing a parabola P. The above parabola P forms the paraboloidal reflection surface of the paraboloidal reflector Ml which is used as the front reflection unit M as shown in Fig. 3B. That is, when the above parabola P is rotated about the Y-axis, a paraboloid of revolution is formed. The desired paraboloidal reflector Ml is formed using a concave paraboloidal surface SF which is a part of the above paraboloid of revolution directed to the driver. The lens unit V, which is mounted to the rear upper portion of the rear windshield, comprises an integrated lens system having a plurality of lenses for reducing aberration of the lens unit V as shown in Figs. 2A and 2B. That is, the lens unit V includes a pair of fixed lenses L which are arrayed in a series. The lens unit V also includes a movable lens LI. The above movable lens LI is movably positioned between the two fixed lenses L. The position of the movable lens LI is selectively adjusted so as to control both the rearview angle and the rearview focus length. The movable lens Ll is driven by a lens moving means. The construction of the above lens moving means is shown in Fig. 4. As shown in the drawing, the lens moving means includes a first motor 1 which is operated in response to handling signals outputted from a control switch (not shown) handled by the driver. The lens moving means also includes a ball screw mechanism which linearly moves the movable lens Ll between the fixed lens L using the rotating force of the motor 1.

The ball screw mechanism includes a pair of ball screws, that is, drive and driven ball screws 11 and 12. The drive ball screw 11 is applied with the rotating force of the motor 1 through a plurality of power transmission gears 10, thereby allowing the movable lens Ll to move while maintaining the angle of the lens Ll relative to the fixed lenses L. Meanwhile, the driven ball screw 12 is driven by the rotating force of the drive ball screw 11. That is, the drive ball screw 11 is connected to the driven ball screw 12 through pulley 13 and timing belt 14. The ball nuts 11' and 12' of the drive and driven ball screws 11 and 12 are coupled to both sides of the movable lens Ll, respectively.

Figs. 5A to 5C are views showing the operation for adjusting the vertical viewing angle of the above lens 921 P - /

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unit V. In order to allow the vertical viewing angle of the unit V to be selectively adjusted, the lens unit V includes a rotatable lens tube 16 for holding the fixed and movable lenses L and Ll. The lens unit V also includes a reflection tube 22 which is pivoted to the above lens tube 16 by means of a hinge joint 30. The reflection tube 22 also mounts the lens tube 16 to the car body. The lens unit V further includes a lens tube rotating means and a reflection means. The lens tube rotating means selectively rotates the lens tube 16 upward and downward. Meanwhile, the reflection means is placed in the reflection tube 22 and used for continuously reflecting light originating from the rotatable lens tube 16 so as to throw the image onto the paraboloidal reflector Ml used as the front reflection unit M.

The lens tube rotating means includes a second motor 2. The rotating force of the above motor 2 is transmitted to a first rotating gear 31 through a drive gear train 33, thereby rotating the lens tube 16. The first rotating gear 31 is connected to the lens tube 16 and gears into the above drive gear train 33. The first rotating gear 31 is applied with the rotating force of the motor 2 through the drive gear train 33, thereby rotating the lens tube 16 about the hinge joint 30 between the tubes 16 and 22. Meanwhile, the reflection means includes an upper reflection panel 20 which is fixed to the upper slant surface 23 inside the reflection tube 22. The reflection means also includes a lower reflection panel 21. The lower reflection panel 21 is mounted to the lower slant surface 24 which is opposite to the upper slant surface 23. The lower reflection panel 21 thus faces the upper reflection panel 20. The above panel 21 is constructed to be rotatable about the hinge joint 30 as shown in the solid and dotted lines of Fig. 5A. The reflection means further includes a second rotating gear 32 which is connected to the lower reflection panel 21. The above second rotating gear 32 is applied with the rotating force of the second motor 2 through the drive gear train 33, thereby rotating the lower reflection panel 21 about the hinge joint 30.

In the rearview mirror system of the invention, the lens unit V is designed to make the rotating angle of the lens tube 16 connected to the first rotating gear 31 become twice that of the lower reflection panel 21 connected to the second rotating gear 32. In the present invention, the above relation between the rotating angles of the tube 16 and panel 21 is easily achieved by adjusting both the number of teeth and turning radiuses of the first and second rotating gears 31 and 32 and drive gear train 33. In the above case, the light reflected by the lower reflection panel 21 is continuously thrown onto the paraboloidal reflector Ml of the front reflection unit M which is placed ahead of the driver.

The operational effect of the above rearview mirror system will be described hereinbelow.

The rotatable lens tube 16 is mounted to the top center inside the rear windshield of the vehicle such that the tube 16 is directed to the back of the vehicle. The lens tube 16 thus throws the light which represents the traffic conditions behind the vehicle onto the paraboloidal reflector Ml placed ahead of the driver. Hence, the driver can be provided with a wider rear view which can be expected when the drive directly sees the traffic conditions behind the vehicle at the rear windshield equipped with the lens tube 16.

That is, the light which represents the traffic conditions behind the vehicle is primarily received into the rotatable lens tube 16 and in turn passes the fixed and movable lenses L and Ll. The light passing the last fixed lens L of the lens tube 16 is reflected by the lower reflection panel 21 and in turn reflected by the upper reflection panels 20 so as to be thrown onto the paraboloidal reflector Ml, thereby producing the image on the reflector Ml. As shown in Fig. 6, the light originating from an object, for example, represented by the arrow "A-B" passes the above-mentioned optical passage for producing one image represented by the arrow "a-b" on the front reflection unit M. In addition, light originating from another object represented by the arrow "C-D" passes the above-mentioned optical passage for producing another image represented by the arrow "c-d" on the front reflection unit M. Therefore, the driver feels the space between the two objects "A-B" and "C-D" behind the vehicle due to the difference between the focus lengths and sizes of the images thrown on the front reflection unit M. Otherwise stated, the driver feels cubic effect while seeing the image thrown on the front reflection unit M.

The field of the rear view provided by the rearview mirror system of this invention can be controlled by moving the movable lens Ll between the two fixed lenses L inside the lens tube 16. In order to move the movable lens Ll, the driver handles a control switch (not shown) to start the first motor 1. When the motor 1 is started, the rotating force of the motor 1 is transmitted to the drive ball screw 11 through the power transmission gears 10, thereby rotating the ball screw 11. The rotating force of the above drive ball screw 11 in turn is transmitted to the driven ball screw 12 through the timing belt 14, thereby causing the screw 12 to be rotated at the same time. As the drive and driven ball screws 11 and 12 are rotated at the same time, the movable lens Ll linearly moves between the fixed lenses L inside the lens tube 16. Thus, the width of light received into the lens tube 16 is adjusted as shown in Figs. 2A and 2B. The driver thus adjusts the field of the rear view provided by the system of this invention by simply handling the control switch provided inside the cabin. In order to adjust the angle of the lens tube 16 upward and downward, the driver handles another control switch (not shown) to start the second motor 2. The rotating force of the motor 2 is thus transmitted to the first and second gears 31 and 32 through the drive gear train 33 at the same time. Both the lens tube 16 and the lower reflection panel 21 thus rotate about the joint 30 while continuously throwing the image of the traffic conditions behind the vehicle onto the paraboloidal reflector Ml, thereby giving a vertically broadened rear view to the driver.

As the rearview mirror system of this invention can give a downwardly broadened rear view to the driver as described above, the system particularly allows the driver to see the traffic conditions just below the back of the vehicle. In this regard, the rearview mirror system of this invention particularly prevents dead angle traffic accidents while backing up the vehicle.

Figs. 7A to 7C are views showing the lens units V in accordance with other embodiments of the present invention. As shown in Fig. 7A, the lens unit V of this invention may exclusively comprise a diverging lens V2. Alternatively, a somewhat cheap Fresnel diverging lens V3 may be substituted for the somewhat expensive diverging lens V2 as shown in Fig. 7B. When using the Fresnel diverging lens V3 in the lens unit, the cost of the rearview mirror system will be reduced. When using the Fresnel diverging lens V3, it is preferred to coat a material, which neither reflects nor transmits the light, on the surfaces SFl of the lens. The above surfaces SFl of the lens V3 are parallel to the light incident axis of the lens V3 as shown in Fig. 7C. When the surfaces SFl are coated with such a material, the resulting Fresnel diverging lens V3 can be free from diffused reflection, thereby providing an excellent lens unit at lower cost. Figs. 8A and 8B are views showing an ellipsoidal reflector M2 suitable to be used as the front reflection unit instead of the paraboloidal reflector Ml in the rearview mirror system of this invention. In order to form the above ellipsoidal reflector M2, an assumed reflection plane ES is drawn. The light originating from the lens unit V will be reflected by that reflection plane ES ahead of the driver, thereby producing an image. The size EO and position EO' of the reflection plane ES are determined, while the size E2 and position E2' of a light transmitting portion of the lens unit V are determined. The light passing the lens unit V will pass the above light transmitting portion of the lens unit V. Furthermore, one fixed point E6 is assumed to be the first focus point. Light originating from another fixed point E3 corresponding to the driver's eye will be reflected by the reflection plane ES and will pass the lens unit V prior to being focused onto the above fixed point E6. The other fixed point E3 corresponding to the driver's eye is assumed to be the second focus point. Thereafter, an ellipse E7 having the above first and second focus points E6 and E3 as its fixed points is drawn. After drawing the ellipse E7, the ellipse E7 is rotated about the straight line passing the first and second focus points E6 and E3, thereby forming an ellipsoid of revolution. The desired ellipsoidal reflector M2 used as the front reflection unit is formed using a concave ellipsoidal surface SF2 which is a part of the above ellipsoid of revolution directed to the driver and from which the light is specularly reflected.

In the present invention, either the paraboloidal reflector ml or the ellipsoidal reflector M2 has a nonspherical concave reflection surface differently from the conventional concave mirrors. The above nonspherical concave reflection surface of either reflector Ml or M2 is formed in accordance with one or both the driver's position and operational conditions of the lens unit V. Therefore, the reflector Ml or M2 easily achieves the excellent image producing effect.

Industrial Applicability

Of course, it will be understood that the above- mentioned reflectors and lenses according to different embodiments of the present invention can be selectively used in the instant rearview mirror system while considering the cost and operational performance of the resulting rearview mirror system. Thus, the present invention can provide different rearview mirror systems with various costs and operational performances.

As described above, the present invention provides an improved rearview mirror system for vehicles. The rearview mirror system of the invention includes a lens unit which is suitable not only for giving a wider rear view to the driver, but also for removing any distortions of an image thrown on the mirror. The above lens unit is mounted to the rear upper portion of the vehicle's cabin. The mirror system also includes a front reflection unit which reflects the light originating from the above lens unit and forms the image to be observed by the driver. The front reflection unit is mounted to the front portion of the cabin ahead of the driver. With both the lens unit and the front reflection unit, the rearview mirror system of the present invention continuously gives a wider and clearer rear view without any distortions of image to the driver regardless of the structural limit of the vehicle and passengers sitting in the back seats. Therefore, the above rearview mirror system is convenient to the driver and allows the driver to drive more safely, thereby preventing dead angle traffic accidents while driving.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A rearview mirror system for vehicles comprising a lens means mounted to an upper portion of a rear windshield of a vehicle and adapted for transmitting light which originates from behind the vehicle, and a front reflection means mounted to a front upper portion of the vehicle ahead of a driver and adapted for reflecting the light to produce an image, wherein said front reflection means comprises: a paraboloidal reflector having a paraboloidal reflection surface, said paraboloidal reflection surface being a part of a paraboloid of revolution directed to the driver, said paraboloid of revolution being produced by assuming the direction of a driver's forward vision to be a negative directional Y-axis, assuming a transverse direction of said vehicle ahead of the driver to be an assumed X-axis, setting the center of an assumed reflection plane for reflecting the light and producing the image ahead of the driver, drawing a curve of a quadratic function Y=AX* passing the center of the assumed reflection plane to draw a parabola, and rotating said parabola about said Y-axis to form said paraboloid of revolution.

2. A rearview mirror system for a vehicle comprising a lens means mounted to an upper portion of a rear windshield of said vehicle and adapted for transmitting light which originates from behind the vehicle, and a front reflection means mounted to a front upper portion of the vehicle ahead of a driver and adapted for reflecting the light to produce an image, wherein said front reflection means comprises: an ellipsoidal reflector having an ellipsoidal reflection surface, said ellipsoidal reflection surface being a part of an ellipsoid of revolution directed to the driver, said ellipsoid of revolution being produced by setting an assumed reflection plane for reflecting the light and producing the image ahead of the driver, setting the size and position of said reflection plane, setting the size and position of a light transmitting portion of said lens means, assuming one fixed point, onto which light originating from another fixed point corresponding to a driver's eye is focused after being reflected by said assumed reflection plane and passing said lens means, to be a first focus point, assuming the other fixed point corresponding to the driver's eye to be a second focus point, drawing an ellipse having said first and second focus points as its fixed points, and rotating said ellipse about a straight line passing the first and second focus points to form said ellipsoid of revolution.

3. The rearview mirror system according to claim 1 or 2, wherein said lens means comprises an integrated lens -

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system having a plurality of lenses for reducing aberration of the lens means.

4. The rearview mirror system according to claim 3, wherein said integrated lens system comprises: a movable lens disposed between said plurality of lenses and selectively moved so as to control both rearview angle and rearview focus length; and means for moving said movable lens.

5. The rearview mirror system according to claim 4, wherein said lens moving means comprises: a motor operated in response to handling signals outputted from a control switch handled by the driver; and a ball screw mechanism linearly moving sa movable lens using the rotating force of said motor.

6. The rearview mirror system according to claim 1 or 2, wherein said lens means includes a means for selectively adjusting the vertical viewing angle of said lens means, said vertical viewing angle adjusting means comprising: a rotatable lens tube adapted for holding said lens means; a reflection tube pivoted to said lens tube by means of a hinge joint and mounting said lens tube to said vehicle; a lens tube rotating means adapted for selectively rotating said lens tube upward and downward; and reflection means placed in said reflection tube and adapted for continuously reflecting the light, originating from said rotatable lens tube, while changing the refraction angles of the light, thereby throwing the image onto said front reflection means.

7. The rearview mirror system according to claim 1 or 2, wherein said lens means includes a diverging lens.

8. The rearview mirror system according to claim 7, wherein said diverging lens is a Fresnel diverging lens.