JP2006031078A - Image pickup device for iris identification, and image pickup method for iris identification - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup device for iris identification which can obtain clear and highly precise images and also obtain sufficiently reliable iris information for personal identification. <P>SOLUTION: When a point A is defined as a point where an image pickup device 8 is set, and a point B is defined as a point where a lighting system 35 is set, and P is defined as a reflection point where light, which is emitted from the lighting system 35, reflects on a cornea 34 of the eyes and is incident to the image pickup device 8, reflects on the cornea 34, the point B is set to the point A so that the following conditional formula (1) or (2) is satisfied: θ<2(asin(p<SB>1</SB>/r)+atan(p<SB>1</SB>/L))...(1), and θ>2(asin(p<SB>2</SB>/r)+atan(p<SB>2</SB>/L))...(2), wherein θis an angle APB, r is the radius of a virtual circle representing the cornea 34, p<SB>1</SB>is the radius of the pupil, p<SB>2</SB>is the radius of the iris, and L is a distance between P and S (object distance), wherein S is an intersection point where a plane, which passes through the point A and is vertical to the optical axis of the image pickup device 8, meets a perpendicular line from a point P to the plane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an iris authentication imaging device that captures an image of an eye illuminated with light from a light source with an imaging element so as to utilize the iris of an eye that has a unique pattern for each individual as authentication information in security or the like, and The present invention relates to an imaging method for iris authentication.

  In recent years, various personal authentication systems have been provided from the viewpoint of security and the like. As one of them, there is an iris authentication system that uses the iris of an eye having unique characteristics for each individual as confirmation information.

  Such an iris authentication system captures an individual's eyes with an image sensor such as a CCD, extracts information (image) relating to the iris from an image obtained by the imaging, and compares it with already registered iris information. Personal authentication is to be performed.

Such an iris authentication system, as described above, requires reliability from the viewpoint of security, etc., so that the entire eye is irradiated with illumination light such as near infrared light in order to obtain a clear and accurate image. Then, there is an image obtained by photographing the whole eye and acquiring iris information from an image obtained thereby. (For example, see Patent Document 1).
JP 2003-36434 A

  By the way, in the iris authentication system disclosed in Patent Document 1, the illumination light applied to the iris is reflected by the iris, and the reflected light is incident on the imaging device, whereby an iris image is captured. ing. At this time, the illumination light passes through a hemispherical transparent cornea covering the iris.

  However, the illumination light is not completely transmitted through the cornea, but part of it is reflected by the surface of the cornea. When the illumination light reflected by the cornea is incident on the imaging device in this way, the illumination light source (light from the light source) is captured as a white spot on the image of the eye and is photographed by the imaging device (so-called catchlight). phenomenon). When the light of the light source reflected in this way hits the image of the iris, the iris in the image will be in a state where the pattern is missing, and reliable iris information cannot be acquired from the captured image was there.

  Therefore, in view of such circumstances, the present invention is capable of acquiring a clear and highly accurate image and capable of acquiring iris information sufficiently reliable in personal authentication, and an iris authentication imaging apparatus, and an iris It is an object to provide an imaging method for authentication.

An imaging apparatus for iris authentication according to the present invention includes an illumination apparatus and an imaging apparatus that photographs an eye in a state where light from the illumination apparatus is irradiated, and the optical axis of the imaging apparatus and the center of the eye substantially coincide with each other An imaging apparatus for iris authentication that shoots an eye in a state where the imaging apparatus is in a state where the installation point of the imaging apparatus is A, the installation point of the illumination apparatus is B, the light is emitted from the illumination apparatus and reflected by the cornea of the eye, and enters the imaging apparatus When the point where the reflected light is reflected on the cornea is P, the installation point B of the illumination device is installed so as to satisfy the following conditional expression (1) or (2) with respect to the installation point A of the imaging device It is characterized by that.
θ <2 (asin (p ₁ / r) + atan (p ₁ / L)) (1)
θ> 2 (asin (p ₂ / r) + atan (p ₂ / L)) (2)
However,
θ: Angle APB
r: radius of a virtual circle representing the cornea of the eye p ₁ : radius of the pupil of the eye p ₂ : radius of the iris of the eye L: a plane that passes through the point A and is perpendicular to the optical axis of the imaging device, and from this point P to the plane Distance PS (Shooting distance) where S is the intersection with the lowered perpendicular

  According to such an imaging apparatus for iris authentication, it is possible to prevent a phenomenon in which, during iris authentication, the illumination light reflected by the illumination device is applied to the iris image, the iris information is lost, and iris authentication cannot be performed. . Hereinafter, the basis will be described with reference to FIG. 6 and FIG.

  In the first place, the mechanism of the phenomenon that the illumination light from the illumination device 35 is reflected on the image of the iris 2 can be explained as follows. As shown in FIG. 6, the illumination light reflected on the cornea 34 and incident on the imaging device 8 is emitted from the installation point B of the illumination device 35, reflected at the point P on the cornea 34, and then installed on the imaging device 8. Point A is reached. At this time, the reflection of the illumination light occurs at the position of this point P.

Therefore, an intersection point between a point Q ₁ on the inner circumference of the iris 2 and a virtual circle R representing the cornea 34 and a straight line parallel to the optical axis of the imaging device 8 is P _1, and a point on the outer circumference of the iris 2 is P ₂ . Then, when the point P is located on the arc P ₁ P ₂ , the reflection of the illumination light is located on the image of the iris 2. That is, if the position of the point B such that the point P is not located on the arc P ₁ P ₂ is indicated, the position of the illumination device 35 is indicated so that no reflection occurs on the image of the iris 2. Hereinafter, the position of the point B that satisfies such a condition will be verified.

FIG. 7 shows the elements of FIG. 6 placed on the xy coordinates, and the center of the virtual circle R of the cornea 34 is placed at the origin O of the xy coordinates. At this time, the installation point A of the imaging device 8 is represented as a point on the x-axis, and the point P is represented as a point on the circle R. The point B passes through the point P and is represented as a point on the straight line PA and the target straight line with the normal line OP of the point P as the axis of symmetry. Here, if the y coordinate of the point P is p and the angle between the normal OP at the point P and the x axis (= the optical axis of the imaging device 8) is θ ′, the following equations (3) and (4) are obtained. To establish.
θ = 2 (θ ′ + atan (p / L)) (3)
θ ′ = asin (p / r) (4)

From (3) and (4), the following equation (5) is established.
θ = 2 (asin (p / r) + atan (p / L)) (5)

Here, since the radius of the pupil 3 is p ₁ and the radius of the iris 2 is p ₂ , the respective y coordinates of the points P ₁ and P ₂ are p ₁ and p ₂ . Therefore, the range of θ when the point P is on the arc P ₁ P ₂ is expressed by the following equation.
2 (asin (p ₁ / r) + atan (p ₁ / L)) ≦ θ ≦ 2 (asin (p ₂ / r) + atan (p ₂ / L)) (6)

  Therefore, if the point B is set so that the value of θ is outside the range shown in the above formula (6), that is, in the range shown in the above formula (1) or (2), the illumination device 35 is placed on the image of the iris 2. The illumination light will not be reflected. Specifically, when θ satisfies Equation (1), the reflection of the illumination device 35 is within the pupil 3, and when θ satisfies Equation (2), the reflection of the illumination device 35 is the iris 2 such as the sclera. As a result, in any case, the reflection of the illumination device 35 on the image of the iris 2 can be prevented from occurring.

  The illumination device includes a light source and a light guide that guides light from the light source to an eye of the person to be authenticated. The light guide includes an incident portion on which light from the light source is incident, and the incident portion. And an annular light guide portion formed with an annular emission surface in plan view for emitting light incident from the imaging device, and the imaging device is guided so that a photographing center substantially coincides with a center of the annular light guide portion. It is preferably provided so as to be capable of photographing through a hole defined in the light part. In this way, since the illumination device can be disposed around the imaging device, it is possible to prevent illumination unevenness of illumination light and generation of shadows and to capture a clear iris. Further, since the imaging device and the illumination device can be unitized, an imaging device for iris authentication that is excellent in versatility can be provided.

  The light source is preferably a flash discharge tube. In this way, for example, a stronger light emission amount can be obtained compared to an LED or the like, and therefore, a clear iris image can be acquired even in an environment where natural light with a large amount of light is irradiated.

  The light source preferably has a dimming function. In this way, for example, a clear and accurate iris image can be acquired by increasing the light amount of the light source in an environment where a large amount of natural light is irradiated.

  Moreover, it is preferable that a visible light filter that blocks the visible light component of the light from the light source and allows the invisible light to pass is provided in the incident portion. Since visible light is not always required for photographing an iris, the visible light that causes glare is blocked. In addition, it is preferable that a visible light filter is comprised so that only the near-infrared light of invisible light may pass. In this way, the iris pattern can be photographed most clearly.

The imaging method for iris authentication according to the present invention irradiates the eye of the person to be authenticated with the light from the illumination device, and makes the eye of the imaging device substantially coincident with the optical axis of the imaging device and the center of the eye. In the imaging method for iris authentication for photographing, the installation point of the imaging device is A, the installation point of the illumination device is B, and the light emitted from the illumination device and reflected by the cornea of the eye and incident on the imaging device is reflected on the cornea When the point to be performed is P, the installation point B of the illumination device is installed so as to satisfy the following conditional expression (1) or (2) with respect to the installation point A of the imaging device.
θ <2 (asin (p ₁ / r) + atan (p ₁ / L)) (1)
θ> 2 (asin (p ₂ / r) + atan (p ₂ / L)) (2)
However,
θ: Angle APB
r: radius of a virtual circle representing the cornea of the eye p ₁ : radius of the pupil of the eye p ₂ : radius of the iris of the eye L: a plane that passes through the point A and is perpendicular to the optical axis of the imaging device, and from this point P to the plane Distance PS (Shooting distance) where S is the intersection with the lowered perpendicular

  According to such an imaging method for iris authentication, it is possible to prevent a phenomenon in which, during iris authentication, the illumination light of the lighting device is reflected on the iris image, the iris information is lost, and iris authentication cannot be performed. . The grounds of the above formulas (1) and (2) are the same as in the case of the imaging device for iris authentication already described.

  According to the imaging device for iris authentication according to the present invention, it is possible to obtain a clear and highly accurate image, and to obtain an excellent effect that iris information sufficiently reliable in personal authentication can be acquired. .

  According to the imaging method for iris authentication according to the present invention, a clear and highly accurate image can be acquired, and an excellent effect that iris information sufficiently reliable in personal authentication can be acquired can be obtained. .

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment according to an imaging apparatus for iris authentication and an imaging method for iris authentication according to the present invention will be described with reference to the accompanying drawings.

  The imaging apparatus for iris authentication according to the present embodiment uses the iris of the eye as authentication information and compares it with previously registered iris information to determine whether or not the person to be authenticated is a registered individual. This is a component of an authentication system that performs personal authentication. Prior to the description of the imaging apparatus for iris authentication, the structure of the eyes photographed by the imaging apparatus for iris authentication will be described. As shown in FIG. 1, each individual eye 1 has an iris 2 composed of a substantially annular region. A pupil 3 having a substantially circular area inscribed in the iris 2 and a sclera 5 (white eye) circumscribing the iris 2 and surrounded by the eyelid 4 are formed. Each person has a completely different pattern.

  As shown in FIGS. 2 and 3, the iris authentication imaging device according to the present embodiment includes an illumination device 35, an imaging device 8, and a casing 9 that houses the illumination device 35 and the imaging device 8. . And the illuminating device 35 is comprised with the light source 6 and the light guide 7 which guides the light from the light source 6 toward a to-be-authenticated person.

  The light source 6 is a well-known flash discharge tube. The flash discharge tube 6 according to the present embodiment has a configuration in which main electrodes 12a and 12b are respectively sealed at both ends of a straight glass bulb 10, and these main electrodes 12a and 12b protrude outward along the axial direction. Become. The flash discharge tube 6 emits light when a charge charged in a main capacitor (not shown) is discharged between the cathode and the anode in the glass bulb 10, that is, between the main electrodes 12a and 12b. The flash discharge tube 6 can be dimmed according to the surrounding environment. For example, the light amount of the light source can be increased in an environment where natural light with a large amount of light is irradiated. Such dimming may be arbitrarily set manually or may be automatically set by using an optical sensor (not shown).

  The light guide 7 is made of a translucent member, and is formed on the annular light guide 13 and a part of the outer periphery of the light guide 13 so that light from the flash discharge tube 6 is incident. Part 14. The light guide unit 13 includes an emission surface 15 having an annular region in plan view on one end surface, and light from the flash discharge tube 6 enters from the outer peripheral surface via the incident unit 14, and the light is guided to the light guide unit. 13 is configured to reach substantially the entire region 13 and exit from the exit surface 15. The incident portion 14 is formed integrally with the light guide portion 13, and is configured such that light from the flash discharge tube 6 enters the light guide portion 13 from the outer peripheral surface of the light guide portion 13. The incident portion 14 is provided with a visible light filter 17 that blocks visible light out of the light from the flash discharge tube 6 and extracts only invisible light. The visible light filter 17 according to the present embodiment is configured to transmit only near-infrared light effective for clearly displaying the pattern of the iris 2.

  The imaging device 8 includes an imaging unit 18 including a solid-state imaging device (not shown) made up of a CCD or the like for imaging the person to be authenticated (eye 1), and an optical system lens (not shown) disposed on the front side of the imaging unit 18. And a lens holder 19 in which an interior is shown. The imaging unit 18 is connected to a separately provided computer (not shown) so that the captured image can be transmitted as image data in order to use the captured image for authentication of the person to be authenticated. The lens holder 19 is focused so that an image of the person to be authenticated (eye 1) located at a predetermined distance from the light guide unit 13 can be formed on the imaging surface (not shown) of the solid-state imaging device in the imaging unit 18. Is set.

  The imaging device 8 having the above configuration is arranged on the inner peripheral surface of the light guide 13 so that the optical axis of the imaging unit 18 passes through the center of the light guide 7 and is perpendicular to the emission circle 15 of the light guide 7. The imaging device 8 is arranged so as to be able to photograph the eye 1 of the person to be authenticated through the hole 20.

  The casing 9 includes a light source interior 21 that houses the flash discharge tube 6 and a light guide interior 22 that houses the light guide 7. The light source interior portion 21 is formed so as to surround a part of the outer peripheral surface of the flash discharge tube 6 (glass bulb 10). In other words, the light source interior portion 21 serves as a reflective shade and surrounds the flash discharge tube 6 so that most of the light emitted from the flash discharge tube 6 is directed to the incident portion 14.

  The light guide interior portion 22 is formed so as to cover the outer peripheral surface of the light guide 7 excluding the incident portion 14 and the inner peripheral surface of the light guide 7 and to cover the other end surface of the light guide 7. Light that is incident on the light guide unit 13 via the incident unit 14 is configured not to be emitted from the outer peripheral surface, the inner peripheral surface, and the other end surface other than the output surface 15 of the light guide unit 13.

  Although not shown, in the present embodiment, a confirmation display for displaying an image captured by the imaging device 8 is provided adjacent to the iris authentication imaging device, and recognizes the image captured by the person to be authenticated. It can be done.

  The imaging apparatus for iris authentication according to the present embodiment has the above-described configuration. Next, a procedure for photographing the iris 2 using the imaging apparatus for iris authentication will be described.

  First, the well-known guide means as described below so that the center of the eye 1 of the person to be authenticated is positioned on the optical axis of the imaging device 8 at a position that is a predetermined distance from the light guide unit 13 (the emission surface 15). (For example, Japanese Patent Application Laid-Open No. 2003-108983).

  That is, first, the person to be authenticated faces the imaging device for iris authentication, and temporarily activates the imaging device for iris authentication. Then, the imaging apparatus for iris authentication continuously pre-photographs the person to be authenticated, and the captured image is displayed on the confirmation display. A guide character image simulating the basic eye 1 is stored in the computer, and the guide character image is superimposed on the captured image and displayed on the confirmation display. The person to be authenticated performs alignment so that the photographed image comes to a position overlapping the guide character image while confirming the display on the confirmation display. When the eye 1 region in the image and the guide character image substantially coincide, the authentication system is fully activated. At this moment, the flash discharge tube 6 emits light. Then, as shown in FIG. 4, the light from the flash discharge tube 6 is irradiated to the substantially entire area of the eye 1 of the person to be authenticated through the light guide 7, and in this state, the imaging device 8 irradiates the substantially entire area of the eye 1. Take a picture. Note that the confirmation display and the iris authentication imaging device are close to each other so that the photographed image of eye 1 does not deviate significantly from the guide character image at the moment when the person to be authenticated puts his eyes on the confirmation display. Arrange.

  The captured image of eye 1 is transmitted to the computer as image data, and only information about the area of iris 2 is extracted from the image of eye 1. Various methods can be used for extracting the region of the iris 2. For example, a threshold value for light and shade is set in advance, and the light and shade of the photographed image is identified based on the threshold value. Only the region may be extracted.

  Then, the iris information registered in the database (the image of iris 2) is compared with the extracted iris information (the image of iris 2). Authentication is complete.

By the way, as already described, the light from the illumination device 35 does not completely pass through the transparent cornea 34 covering the iris 2, and a part of the light is reflected on the surface of the cornea 34 and is white on the image of the eye 1. And captured by the imaging device 8 (so-called catchlight phenomenon). In the imaging apparatus for iris authentication according to the present embodiment, the positional relationship between the imaging apparatus 8 and the illumination apparatus 35 is devised so that the reflection of the illumination apparatus 35 does not reach the iris image. . That is, the installation point of the imaging device 8 is A, the installation point of the illumination device 35 is B, and the point of the light that is emitted from the illumination device 35 and reflected by the cornea 34 of the eye and incident on the imaging device 8 is reflected on the cornea 34. When P is set, the installation point B of the illumination device 35 is installed so as to satisfy the following conditional expression (1) or (2) with respect to the installation point A of the imaging device 8.
θ <2 (asin (p ₁ / r) + atan (p ₁ / L)) (1)
θ> 2 (asin (p ₂ / r) + atan (p ₂ / L)) (2)
However,
θ: Angle APB
r: radius of a virtual circle representing the cornea 34 of the eye 1 p ₁ : radius of the pupil 3 of the eye 1 p ₂ : radius of the iris 2 of the eye 1 L: a plane passing through the point A and perpendicular to the optical axis of the imaging device 8 , Distance PS (shooting distance) where S is the intersection with a perpendicular drawn from point P on this plane

  The reason why the reflection of the illumination device 35 does not reach the image of the iris 2 by such setting will be described with reference to FIGS.

  First, the structure of the above-described eye 1 will be specifically described. As shown in FIG. 5, the eye 1 includes a substantially spherical glass body 32, a crystal body 33 formed on the front surface of the glass body 32, a substantially annular iris 2 formed on the front surface of the crystal body 33, a crystal body 33, and It is formed of a substantially hemispherical transparent cornea 34 that covers the iris 2 from the front, and a sclera 5 that is formed continuously with the outer peripheral edge of the cornea 34 and covers the spherical portion of the glass body 32. The central hole of the iris 2 is a pupil 3, and the eye 1 adjusts the amount of light incident on the crystalline lens 33 by adjusting the degree of opening of the pupil 3.

  The mechanism of the phenomenon that the illumination light from the illumination device 35 is reflected on the image of the iris 2 from the structure of the eye 1 can be explained as follows. As shown in FIG. 6, the illumination light reflected on the cornea 34 and incident on the imaging device 8 is emitted from the installation point B of the illumination device 35, reflected at the point P on the cornea 34, and then installed on the imaging device 8. Point A is reached. At this time, the reflection of the illumination light occurs at the position of this point P.

Therefore, an intersection point between a point Q ₁ on the inner circumference of the iris 2 and a virtual circle R representing the cornea 34 and a straight line parallel to the optical axis of the imaging device 8 is P _1, and a point on the outer circumference of the iris 2 is P ₂ . Then, when the point P is located on the arc P ₁ P ₂ , the reflection of the illumination light is located on the image of the iris 2. That is, if the position of the point B such that the point P is not located on the arc P ₁ P ₂ is indicated, the position of the illumination device 35 is indicated so that no reflection occurs on the image of the iris 2. Hereinafter, the position of the point B that satisfies such a condition will be verified.

FIG. 7 shows the elements of FIG. 6 placed on the xy coordinates, and the center of the virtual circle R of the cornea 34 is placed at the origin O of the xy coordinates. At this time, the installation point A of the imaging device 8 is represented as a point on the x-axis, and the point P is represented as a point on the circle R. The point B passes through the point P and is represented as a point on the straight line PA and the target straight line with the normal line OP of the point P as the axis of symmetry. Here, if the y coordinate of the point P is p and the angle between the normal OP at the point P and the x axis (= the optical axis of the imaging device 8) is θ ′, the following equations (3) and (4) are obtained. To establish.
θ = 2 (θ ′ + atan (p / L)) (3)
θ ′ = asin (p / r) (4)

From (3) and (4), the following equation (5) is established.
θ = 2 (asin (p / r) + atan (p / L)) (5)
Here, since the radius of the pupil 3 is p ₁ and the radius of the iris 2 is p ₂ , the respective y coordinates of the points P ₁ and P ₂ are p ₁ and p ₂ . Therefore, the range of θ when the point P is on the arc P ₁ P ₂ is expressed by the following equation.
2 (asin (p ₁ / r) + atan (p ₁ / L)) ≦ θ ≦ 2 (asin (p ₂ / r) + atan (p ₂ / L)) (6)

  Therefore, if the point B is set so that the value of θ is outside the range shown in the above formula (6), that is, in the range shown in the above formula (1) or (2), the illumination device 35 is placed on the image of the iris 2. The illumination light will not be reflected. Specifically, when θ satisfies Equation (1), the reflection of the illumination device 35 is within the pupil 3, and when θ satisfies Equation (2), the reflection of the illumination device 35 is the iris 2 such as the sclera. As a result, in any case, the reflection of the illumination device 35 on the image of the iris 2 can be prevented from occurring.

By the way, it is known that the radius of the pupil 3 is about 1.5 mm in the most narrowed state, the radius of the iris 2 is about 5 mm, and the radius of the cornea 34 is about 6 mm. Therefore, in the above conditional expressions (1) and (2), p ₁ = 1.5, p ₂ = 5.0, r = 6.0, and L = 30 mm, 40 mm,. The value of θ was calculated by substitution. The results are shown in Table 1 (however, the numerical units in the table are all in radians).

表１より、例えば、点Ｐが点Ｐ₁上にあるとき、Ｌ＝３０ｍｍでは、θ＝０．６０５２７７となる。このとき、例えば撮像装置３５の設置点Ａを通りｘ軸に垂直な平面上に照明装置の設置点Ｂを置くものとして計算すると、距離ＡＢ≒１８．６ｍｍとなる。すなわち、照明装置３５を撮像装置８から１８．６ｍｍ未満の距離に置けば、映り込みを瞳孔２内に収めることができ、虹彩２への映り込みが生じなくなる。

From Table 1, for example, when the point P is on the point P ₁ , θ = 0.605277 at L = 30 mm. At this time, for example, when calculating that the installation point B of the illumination device is placed on a plane that passes through the installation point A of the imaging device 35 and is perpendicular to the x-axis, the distance AB≈18.6 mm. That is, if the illumination device 35 is placed at a distance of less than 18.6 mm from the imaging device 8, the reflection can be stored in the pupil 2 and the reflection on the iris 2 does not occur.

  As described above, the installation position of the illumination device 35 is set so as to satisfy the conditional expression (1) or (2) with respect to the installation position of the imaging device 8, so that the reflection of the illumination device 35 is an image of the iris 2. It was shown that it was not reflected on the top. That is, in the iris authentication imaging device of the present embodiment, the conditional expression (1) is obtained with respect to the projecting state and the radial dimension of the annular light guide of the illumination device 35 with respect to the installation position of the imaging device 8. ) Or setting within the range of (2), it can be said that the reflection of the illumination device 35 does not appear on the image of the iris 2.

  In the above description, all the elements in FIG. 7 are placed on the first quadrant of the xy coordinates. However, by considering each element by rotating it around the x axis, This shows the positional relationship in the three-dimensional space.

  In addition, since the size of each part of the eye 1 may be slightly different from person to person, even if the above condition is satisfied, the reflection of the illumination device 35 may cause the image of the iris 2 to be slightly lost. However, as in the conventional example, it is certain that the probability that the information of the iris 2 is lost and authentication cannot be performed is significantly reduced as compared with the case where no special device is applied.

  As described above, in the imaging device for iris authentication according to the present embodiment, the imaging device 8 is installed at the center of the annular light guide as the exit surface of the illumination device 35, and the positions of the imaging device 8 and the light guide. The relationship is set so as to satisfy the formulas (1) and (2). Therefore, at the time of iris authentication, an image of the iris 2 due to the reflection of the illumination device 35 is not lost, and reliable iris authentication can be performed. In addition, since the illumination device 35 can be disposed around the imaging device 8, illumination illumination unevenness and shadows can be prevented, and a clear iris can be photographed. Moreover, since the imaging device 8 and the illumination device 35 can be unitized, an imaging device for iris authentication having excellent versatility can be provided.

  In addition, since the flash discharge tube 6 is used as a light source, it is possible to obtain a stronger light emission amount than that of, for example, an LED or the like. can do.

  In addition, since the flash discharge tube 6 has a dimming function, for example, a clear and accurate iris image can be obtained by increasing the light amount of the light source in an environment where a large amount of natural light is irradiated. Can do.

  In addition, since the visible light filter 17 that allows only near-infrared light to pass through is provided at the incident portion 14, the iris 2 can be photographed clearly, and visible light that causes glare can be blocked and used easily.

  As described above, the imaging apparatus for iris authentication can acquire a clear and highly accurate image, and can acquire iris information having sufficient reliability for personal authentication such as security.

  The iris authentication imaging device and the iris authentication imaging method of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. It is.

  In the above embodiment, the visible light filter 17 is provided in the incident portion 14 of the light guide 7 and only the near infrared light is irradiated from the light guide 7. However, the present invention is not limited to this. Of course, not only near-infrared light but also invisible light including other wavelengths may be allowed to pass, or visible light may be emitted toward the eyes of the person to be authenticated without providing the visible filter 17. Good. However, it is preferable to provide the visible light filter 17 in order to capture the iris 2 clearly without causing discomfort due to glare.

  Moreover, in the said embodiment, although the flash discharge tube 6 was used as a light source, it is not limited to this, For example, other light sources, such as LED, can be used. However, in order to obtain a sufficient amount of light for photographing the iris 2, it is most preferable to use the flash discharge tube 6.

  The imaging apparatus for iris authentication and the imaging method for iris authentication according to the present invention can acquire a clear and highly accurate image, and can acquire sufficiently reliable iris information in personal authentication. It is useful in the field of personal authentication systems that take images of eyes illuminated by light from a light source with an image sensor so that the iris of each eye can be used as authentication information in security, etc. It is.

1 is a front view of an eye that is an imaging target of an imaging apparatus for iris authentication according to an embodiment of the present invention. Vertical sectional view of an imaging apparatus for iris authentication according to the embodiment The top view including the partial cross section of the imaging device for iris authentication which concerns on the same embodiment Image diagram of use state of imaging apparatus for iris authentication according to same embodiment Longitudinal cross-sectional view of an eye that is a subject to be photographed by the iris authentication imaging apparatus according to the embodiment A longitudinal sectional view showing the positional relationship among the eyes, the imaging device, and the illumination device Xy plan view with the center of the virtual circle of the cornea in FIG. 6 as the origin

Explanation of symbols

1 eye 2 iris 3 pupil 4 eyelid 5 sclera (white eye)
6 Flash discharge tube (light source)
DESCRIPTION OF SYMBOLS 7 Light guide 8 Image pick-up device 9 Casing 10 Glass bulb 12a, 12b Main electrode 13 Light guide part 14 Incident part 15 Outgoing surface 17 Visible light filter 18 Imaging part 19 Lens holder 20 Hole part 21 Light source interior part 22 Light guide body interior part 31 Eyeball 32 Glass Body 33 Crystal Body 34 Cornea 35 Illumination Device

Claims (6)

For iris authentication, comprising an illuminating device and an imaging device that shoots an eye in a state in which light from the illuminating device is irradiated, and shoots an eye in a state in which the optical axis of the imaging device is substantially coincident with the center of the eye An imaging device,
When the installation point of the imaging device is A, the installation point of the illumination device is B, and the point where light emitted from the illumination device and reflected by the cornea of the eye and incident on the imaging device is reflected by the cornea is P, An imaging apparatus for iris authentication, wherein the installation point B of the illumination device is installed so as to satisfy the following conditional expression (1) or (2) with respect to the installation point A of the imaging apparatus.
θ <2 (asin (p ₁ / r) + atan (p ₁ / L)) (1)
θ> 2 (asin (p ₂ / r) + atan (p ₂ / L)) (2)
However,
θ: Angle APB
r: radius of a virtual circle representing the cornea of the eye p ₁ : radius of the pupil of the eye p ₂ : radius of the iris of the eye L: a plane that passes through the point A and is perpendicular to the optical axis of the imaging device, and from this point P to the plane Distance PS (Shooting distance) where S is the intersection with the lowered perpendicular The illumination device includes a light source and a light guide that guides light from the light source to an eye of the person to be authenticated, and the light guide is incident on the light incident from the light source and the light incident from the light incident portion. An annular light guide part formed with an annular emission surface in plan view for emitting the emitted light,
2. The iris authentication according to claim 1, wherein the imaging device is provided so as to be capable of photographing through a hole defined in the light guide so that a photographing center substantially coincides with a center of the annular light guide. Imaging device.   The imaging apparatus for iris authentication according to claim 1, wherein the light source is a flash discharge tube.   The imaging device for iris authentication according to any one of claims 1 to 3, wherein the light source has a dimming function.   The imaging apparatus for iris authentication according to any one of claims 1 to 4, wherein a visible light filter that blocks a visible light component of light from the light source and allows invisible light to pass through is provided in the incident portion. In an imaging method for iris authentication in which light from the illumination device is irradiated to the person to be authenticated, and the optical axis of the imaging device and the center of the eye are substantially matched, and the eye is photographed by the imaging device.
When the installation point of the imaging device is A, the installation point of the illumination device is B, and the point where light emitted from the illumination device and reflected by the cornea of the eye and incident on the imaging device is reflected by the cornea is P, An imaging method for iris authentication, wherein the installation point B of the illumination device is installed so as to satisfy the following conditional expression (1) or (2) with respect to the installation point A of the imaging device.
θ <2 (asin (p ₁ / r) + atan (p ₁ / L)) (1)
θ> 2 (asin (p ₂ / r) + atan (p ₂ / L)) (2)
However,
θ: Angle APB
r: radius of a virtual circle representing the cornea of the eye p ₁ : radius of the pupil of the eye p ₂ : radius of the iris of the eye L: a plane that passes through the point A and is perpendicular to the optical axis of the imaging device, and from this point P to the plane Distance PS (Shooting distance) where S is the intersection with the lowered perpendicular

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