WO2015119078A1

WO2015119078A1 - Biometric authentication device using finger authentication prism and biometric authentication method

Info

Publication number: WO2015119078A1
Application number: PCT/JP2015/052839
Authority: WO
Inventors: 輝幸樋口
Original assignee: 日本電気株式会社
Priority date: 2014-02-06
Filing date: 2015-02-02
Publication date: 2015-08-13
Also published as: JPWO2015119078A1; JP6443349B2

Abstract

This biometric authentication device uses a finger authentication prism that has a trapezoid shape when viewed from the side and is provided with: a finger mounting surface on which a finger to be authenticated is placed; an imaging surface that is arranged to face the finger mounting surface in parallel; and a reflection surface that is positioned at a prescribed angle relative to the finger mounting surface and the imaging surface such that, subsequent to irradiated light being reflected by the finger mounting surface, the irradiated light is totally reflected and reaches the imaging surface. When the imaging surface of the finger authentication prism is exposed to visible light and/or infrared light, the light reflected by the finger placed on the finger mounting surface is branched between a first light path that reaches the imaging surface directly, and a second light path that reaches the imaging surface from the finger mounting surface via the reflection surface. From amongst the reflected light that has traveled the first light path and the second light path, the biometric authentication device forms a first image on the basis of the reflected light corresponding to a region of the finger extending from the distal interphalangeal joint in the fingertip direction, and forms a second image on the basis of reflected light corresponding to a region of the finger extending from the distal interphalangeal joint in the finger-base direction.

Description

Biometric authentication device and biometric authentication method using finger authentication prism

The present invention relates to a biometric authentication apparatus and a biometric authentication method using a finger authentication prism.
This application claims priority based on Japanese Patent Application No. 2014-21109 for which it applied to Japan on February 6, 2014, and uses the content here.

Conventionally, biometric authentication devices and biometric authentication methods that perform personal authentication by reading fingerprints and finger veins have been developed and disclosed in various documents. Patent Document 1 discloses an optical image acquisition system as a biometric authentication device, and performs personal authentication using a fingerprint that forms a biometric feature using a total reflection critical angle by a triangular prism. The biometric authentication device reads irregularities (that is, ridges and valleys) on the skin surface of the finger, and can easily obtain a high-contrast fingerprint image. For this reason, it is compatible with a “print fingerprint” which is obtained by applying ink to a fingertip and pressing it onto paper, and is used in the judicial bureau, police station and the like.

Patent Document 2 discloses an authentication device and an authentication method for collecting an image of a finger using a prism having a truncated pyramid shape. Patent Document 3 discloses a personal identification device that performs personal identification based on a blood vessel fluoroscopic image obtained by imaging a subcutaneous blood vessel pattern of a hand. Patent Document 4 discloses a personal identification device for personal identification based on a fingerprint image. Patent Document 5 discloses a biometric authentication device that performs personal authentication by reading a plurality of biometric images using a prism. Patent Document 6 discloses a biometric authentication apparatus that can simultaneously perform iris authentication, fingerprint authentication, and vein authentication. Patent Document 7 discloses an authentication imaging device that captures an authentication pattern of a palm or a finger. Patent Document 8 discloses an authentication imaging device that photographs a finger and a palm.

In recent years, criminal acts have been seen in which a finger forged with a resin such as silicon is used, or a forged film of a translucent fingerprint having irregularities is applied to the tip of the finger to impersonate another person. In order to detect the criminal act, it is conceivable that in addition to a high-contrast image that performs fingerprint verification, a natural image of a visible finger to detect forgery is acquired and the inspector visually confirms the fingerprint and the like. . In view of this, a biometric authentication device that adopts a non-contact method in which a finger does not contact a prism and obtains a fingerprint image that is close to that seen with the naked eye and performs biometric authentication has been proposed (see Patent Document 4).

US Pat. No. 6,381,347 International Publication WO2012 / 133110A1 JP 7-21373 A JP 2003-85538 A JP 2006-65400 A JP 2008-113704 A JP 2009-175810 A JP 2009-252052 A

By the way, although many databases that have recorded fingerprints using conventional prisms have been created, it is necessary to ensure compatibility with images captured by the biometric authentication device from the viewpoint of information transferability. Further, the merit of the image of the imprinted fingerprint is that it can be easily compared with the retained fingerprint. Remnant fingerprints are fingerprints left on the criminal scene and can be a decisive factor in criminal investigations, and are useful as judicial evidence.

However, when shooting a fingerprint without pressing the finger against the glass as in the non-contact method, the finger can be flexibly deformed, so the image of the finger shot against the glass and the finger taken without pressing against the glass The degree of change in the shape of the finger differs from the image, and the contact-type finger fingerprint image differs from the non-contact-type finger fingerprint image.

Therefore, the fingerprint image taken by the non-contact method is not compatible with the imprint fingerprint using the prism. Further, in the visual inspection method used by the judicial authorities, fingerprint images taken by the non-contact method have a small contrast and are inappropriate. In recent years, biometric authentication has been performed by combining a plurality of biometric features in addition to fingerprints in order to increase the accuracy of biometric verification. In particular, since the finger blood vessel pattern is an effective biometric feature, personal verification is performed by combining the finger fingerprint and the blood vessel pattern.

On the other hand, in order to prevent criminal acts such as using fingers forged with resin such as silicon or impersonating others by pasting a semi-transparent fingerprint forged film with irregularities on the tip of the finger, In addition, a natural image of the finger is also acquired. However, in order to acquire an image showing a plurality of biometric features, a plurality of imaging devices are required, or a predetermined biometric feature has to be shot a plurality of times, and the biometric authentication device is enlarged, or personal verification is performed. This will increase the time required for image acquisition.

The present invention solves the above problems, and an object of the present invention is to provide a biometric authentication apparatus and a biometric authentication method using a finger authentication prism that can perform highly accurate personal authentication in a short time.

A first embodiment of the present invention is a biometric authentication device that includes a finger authentication prism, an imaging device, a visible light source, and an infrared light source. The finger authentication prism includes a finger placement surface on which a finger to be authenticated is placed, an imaging surface disposed in parallel and opposite to the finger placement surface, and a reflection disposed at a predetermined angle with respect to the finger placement surface and the imaging surface. A surface. The finger authentication prism is arranged so that the longitudinal direction of the finger installation surface coincides with the longitudinal direction of the finger. Irradiation light from a visible light source and / or an infrared light source is incident from the imaging surface, propagates through the finger authentication prism, is reflected by the finger placed on the finger installation surface, and then is totally reflected by the reflecting surface and is then imaged. The reflecting surface is formed at a predetermined angle so as to reach. The imaging device is disposed in the vicinity of the imaging surface of the finger authentication prism, and the irradiation light from the visible light source and / or the infrared light source is reflected by the finger on the finger installation surface and directly reaches the imaging surface. Imaging is performed based on the reflected light that has passed through and the reflected light that has passed through the second optical path through which the irradiated light reaches the imaging surface from the finger installation surface through the reflecting surface.

According to a second aspect of the present invention, a finger installation surface on which a finger to be authenticated is placed, an imaging surface disposed opposite to and parallel to the finger installation surface, and a predetermined angle with respect to the finger installation surface and the imaging surface A trapezoidal finger authentication prism having a reflecting surface disposed in the side view. The first reflecting surface directly reaches the imaging surface after the visible light and / or infrared light is irradiated on the imaging surface, propagates through the finger authentication prism and is reflected by the finger placed on the finger installation surface. It is formed at a predetermined angle so as to secure the optical path and the second optical path that is totally reflected by the reflecting surface from the finger installation surface and reaches the imaging surface.

According to a third aspect of the present invention, a finger installation surface on which a finger to be authenticated is placed, an imaging surface disposed opposite to and parallel to the finger installation surface, and total reflection after irradiation light is reflected by the finger installation surface This is a biometric authentication method using a finger authentication prism having a finger installation surface and a reflective surface arranged at a predetermined angle with respect to the image pickup surface so as to reach the image pickup surface. Here, when the imaging surface is irradiated with visible light and / or infrared light, the reflected light from the finger placed on the finger installation surface directly reaches the imaging surface and the finger installation surface. The light is branched to a second optical path that reaches the imaging surface via the reflecting surface. Of the reflected light that has passed through the first optical path and the second optical path, a first image is taken based on the reflected light corresponding to the part in the fingertip direction from the distal interphalangeal joint of the finger. In addition, a second image is captured based on the reflected light corresponding to the portion in the root direction of the finger from the joint between the distal interphalangeal joints of the finger among the reflected light that has passed through the first optical path and the second optical path.

According to the biometric authentication device and the biometric authentication method of the present invention, it is possible to simultaneously acquire a high-contrast image, a blood vessel pattern image of a finger, and a natural image of a visible finger with a single imaging device. it can.

It is the side view and XY arrow sectional drawing of the finger authentication prism used for the biometrics apparatus which concerns on one Example of this invention. It is a top view of a finger authentication prism. It is a schematic diagram which shows the state which put the finger | toe on the finger | toe installation surface of a finger authentication prism. It is a schematic diagram explaining the optical path of the reflected light of the valley line part of a finger at the time of placing a finger on the finger authentication prism of the biometric authentication device. It is a schematic diagram explaining the optical path of the reflected light of the ridge part of a finger when a finger is placed on the finger authentication prism of the biometric authentication device. It is the schematic diagram which showed a mode that a natural image and a contrast image were image | photographed based on the reflected light of the valley line part and ridge part of a finger | toe at the time of mounting a finger on the finger authentication prism of a biometrics authentication apparatus. It is a schematic diagram which shows a mode that the infrared-light cut filter and the infrared-light transmission visible light filter were installed in the imaging surface of the finger authentication prism of a biometrics authentication apparatus. It is a figure which shows an example of the image of the finger | toe image | photographed with the biometrics apparatus. It is a block diagram of the biometrics apparatus which concerns on the modification of the Example of this invention. It is a block diagram of the fingerprint authentication apparatus using the biometric authentication apparatus which concerns on this invention. It is a figure which shows an example of the image of the finger | toe image | photographed with the fingerprint authentication apparatus.

FIG. 1 shows the configuration of a side-view trapezoidal finger authentication prism 1 used in a biometric authentication apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 10 indicates a finger installation surface on which a finger is installed, and reference numeral 11 indicates an imaging surface on which an imaging device such as a camera is arranged. The imaging surface 11 is formed in parallel with the finger installation surface 10. Reference numeral 12 denotes a reflection surface, and reference numeral 13 denotes an opposing surface. The reflective surface 12 is inclined at a predetermined angle with respect to the finger placement surface 10 and the imaging surface 11, and the surface 13 facing the reflective surface 12 is perpendicular to the finger placement surface 10 and the imaging surface 11. Further, the cross-sectional view taken along the line XY as viewed from the reflecting surface 12 has a rectangular shape.

FIG. 2 is a plan view of the finger authentication prism 1 as viewed from the finger installation surface 10. As shown in FIG. 2, the finger installation surface 10 and the reflection surface 12 have a rectangular shape in plan view, and the finger installation surface 10 has a rectangular shape with the longitudinal direction of the finger 2 as the long side. For this reason, the finger 2 is placed so that its longitudinal direction is along the longitudinal direction of the finger installation surface 10.

The reflection surface 12 totally reflects light in the finger authentication prism 1 on the finger installation surface 10 in an optical path that reaches the finger installation surface 10 from the imaging surface 11 via the reflection surface 12 when the imaging surface 11 is irradiated with light. It is installed at such an angle. In other words, the light incident on the reflection surface 12 from the finger installation surface 10 through the air layer to the inside of the finger authentication prism 1 is reflected on the reflection surface 12 due to the difference between the refractive index of the air layer and the refractive index of the finger authentication prism 1 itself. The light that does not reach and is reflected by the finger installation surface 10 is installed at an angle at which it is totally reflected toward the imaging surface 11.

Next, various optical paths formed inside the finger authentication prism 1 will be described with reference to FIGS. In the following description, a case where the biometric authentication target is the finger 2 will be described, but the present invention is not limited to this. For example, the present invention can also be applied to palm palm pattern authentication. In the present embodiment, as shown in FIG. 4, a visible light source 3 and an infrared light source 4 are arranged below the finger authentication prism 1, and the irradiation light is reflected by the finger 2 placed on the finger installation surface 10. It is assumed that the imaged light is imaged by the imaging device 5 installed below the imaging surface 11. 4 to 6 are cross-sectional views of the biometric authentication device viewed from the front end side (or the front direction) of the finger 2 placed on the finger authentication prism 1, and FIG. It is sectional drawing seen from the longitudinal direction (or horizontal direction).

Light emitted from the visible light source 3 and the infrared light source 4 disposed below the finger authentication prism 1 is reflected by the valley and ridge portions of the finger 2 placed on the finger installation surface 10 of the finger authentication prism 1. Is done. Here, the trough portion means a distal interphalangeal joint of the finger 2 that is not in contact with the finger installation surface 10 (including a portion in the direction from the first joint of the finger to the root of the finger).

As shown in FIG. 3, since the ridge portion of the finger 2 is in contact with the finger installation surface 10, the refractive index of the light reflected by the ridge portion of the finger 2 is that of the finger authentication prism 1 (ie, glass). It is almost the same as the refractive index. Therefore, the light reflected by the ridge portion of the finger 2 can be handled in the same manner as the light reflected by the finger installation surface 10. That is, since the light reflected by the ridge portion of the finger 2 is radiated in all directions within the finger authentication prism 1, it can reach all the regions below the finger installation surface 10.

On the other hand, the valley portion of the finger 2 is not in contact with the finger placement surface 10, and an air layer is formed between the valley portion of the finger 2 and the finger placement surface 10. Therefore, the reflected light of the valley line part of the finger 2 is transmitted through the finger installation surface 10 through the air layer. However, the refractive index of air is “1.0”, the refractive index of glass is “1.3” to “1.5”, and the refractive index of moisture and skin is “1.3” to “1.4”. . Due to the difference in refractive index, the reflected light of the valley portion of the finger 2 undergoes a refraction phenomenon different from the reflected light of the ridge portion of the finger 2. For this reason, the reflected light of the valley portion of the finger 2 is not radiated in all directions in the finger authentication prism 1, and the reflected light does not reach a predetermined range in the finger authentication prism 1. The reflection surface 12 is installed at an angle at which the light in the finger authentication prism 1 is totally reflected by the finger installation surface 10 in the optical path from the imaging surface 11 through the reflection surface 12 to the finger installation surface 10. In other words, the reflecting surface 12 is a range in which the light that has passed through the finger placement surface 10 from the air layer and entered the finger authentication prism 1 does not reach, and the light reflected by the finger placement surface 10 is the imaging surface 11. It is installed at an angle that totally reflects toward the.

As shown in FIG. 4, since the light reflected by the valley line portion of the finger 2 and transmitted through the air layer to the finger installation surface 10 does not reach the reflection surface 12, imaging is performed from the finger installation surface 10 through the reflection surface 12. There is no reflected light from the valley line that reaches the surface 11, and there is only reflected light that directly reaches the imaging surface 11 from the finger installation surface 10.

Next, with respect to the optical path related to the ridge portion of the finger 2, the light reflected by the ridge portion of the finger 2 is radiated in all directions in the finger authentication prism 1 to all regions below the finger installation surface 10. To reach. Therefore, as shown in FIG. 5, there is an optical path that reaches the imaging surface 11 by being reflected by the reflecting surface 12 together with an optical path that directly reaches the imaging surface 11.

As shown in FIG. 6, the imaging device 5 captures two types of images transmitted through the imaging surface 11 in order to capture the light transmitted through the imaging surface 11. The first image is generated by an optical path through which reflected light from the ridge portion of the finger 2 reaches the imaging surface 11 from the finger installation surface 10 through the reflection surface 12. Since the first image is generated only by the reflected light of the ridge portion of the finger 2, a fingerprint image (hereinafter referred to as a high-contrast image and a high contrast image) where the valley portion of the finger 2 is dark and the ridge portion of the finger 2 is bright. Called). The second image is generated by an optical path that directly reaches the imaging surface 11 among the reflected light reflected by the valley and ridge portions of the finger 2 placed on the finger installation surface 10. Since the second image is a direct view of the finger 2 placed on the finger installation surface 10 from the imaging surface 11, the image captured by the imaging device 5 is a natural image of the finger 2 (hereinafter referred to as a natural image). Called). By using the finger authentication prism 1 as described above for the biometric authentication device, as shown in FIG. 6, a high-contrast image and a natural image can be simultaneously captured by one imaging using one imaging device 5. .

In addition, since it is only necessary to determine whether the fingerprint image is a fake or genuine image, it is not always necessary to acquire a wide image. Rather, it is desirable to analyze in detail with large images. When the finger 2 is imaged using the finger authentication prism 1 according to the present embodiment, the natural image is generated by an optical path that directly reaches the imaging surface 11 from the finger installation surface 10, and the optical path is the shortest optical path. Therefore, it is possible to obtain a natural image large enough to detect forgery.

On the other hand, since a high-contrast image is used for fingerprint collation, it is desirable to acquire a fingerprint image in a wide area so that there are many feature points. In order to acquire a fingerprint image of a wide area, it is necessary to lengthen the optical path from the finger installation surface 10 to the imaging surface 11. When the finger 2 is imaged using the finger authentication prism 1 according to the present embodiment, the optical path for obtaining a high-contrast image reaches the imaging surface 11 from the finger installation surface 10 through the reflection surface 12, and thus there are many feature points. It is possible to take a sufficient length to photograph a fingerprint image of such a wide area.

As described above, by using the finger authentication prism 1 according to the present embodiment, a high-contrast image and a natural image can be simultaneously photographed by the imaging device 5 once. In the present embodiment, not only the visible light source 3 for fingerprint imaging but also an infrared light source 4 for imaging a finger blood vessel pattern is used.

The image for fingerprint collation is mainly an image of the fingerprint imprinted part in the fingertip direction from the distal interphalangeal joint (first joint) of the finger. The visible light source 3 is suitable for taking a fingerprint collation image. On the other hand, images for blood vessel pattern matching are images of the root direction of the finger from the distal interphalangeal joint (first joint), and are mainly close to the distal interphalangeal joint (first joint) of the finger. This corresponds to the part up to the interphalangeal joint (second joint). An infrared light source 4 is suitable for capturing a blood vessel pattern matching image.

Therefore, the image in the fingertip direction from the distal interphalangeal joint (first joint) of the finger is used for fingerprint collation and confirmation of fingerprint forgery. In order to eliminate the influence of infrared light, the finger placement surface An image in the fingertip direction from the distal interphalangeal joint (first joint) of the finger among the reflected light of the optical path that reaches the imaging surface 11 from 10 through the reflective surface 12 and the reflected light of the optical path that directly reaches the imaging surface 11 The reflected light corresponding to is taken after removing the infrared light component. Specifically, as shown in FIG. 7, at the position of the imaging surface 11 corresponding to the fingertip direction side centering on the distal interphalangeal joint (first joint) of the finger in the angle of view of the imaging device 5. Then, an infrared light cut filter 6 is installed to remove the infrared light component from the reflected light.

On the other hand, in order to remove the influence of visible light on the image of the finger base direction side from the distal interphalangeal joint (first joint) used for collation of the blood vessel pattern of the finger by infrared light, the finger placement surface Among the reflected light of the optical path that reaches the imaging surface 11 from 10 through the reflective surface 12 and the reflected light of the optical path that directly reaches the imaging surface 11, the finger base direction from the distal interphalangeal joint (first joint) of the finger The reflected light corresponding to the side image is taken after removing the visible light component. Specifically, as shown in FIG. 7, the imaging surface 11 corresponding to a portion on the finger base direction side with the distal interphalangeal joint (first joint) of the finger as the center of the angle of view of the imaging device 5. The far-infrared light transmission visible light cut filter 7 for removing the visible light component from the reflected light is installed at the position.

FIG. 8 shows an example of a finger image taken by the biometric authentication apparatus according to the embodiment of the present invention. According to the present embodiment, a high-contrast image for fingerprint verification from the distal interphalangeal joint (first joint) to the fingertip direction and a forgery in the fingertip direction from the distal interphalangeal joint (first joint) And an image of a blood vessel pattern in the direction from the distal interphalangeal joint (first joint) to the root of the finger can be acquired by one imaging device 5 by one imaging.

In the biometric authentication apparatus shown in FIG. 7, the infrared light cut filter 6 and the infrared light transmission visible light cut filter 7 are provided as means for removing the infrared light component or the visible light component from the reflected light. However, the present invention is not limited to this. It is not a thing. For example, the imaging device 5 has an imaging element sensitive to only visible light or a distal phalanx of the finger in order to receive reflected light corresponding to an image in the fingertip direction from the distal interphalangeal joint (first joint) of the finger. In order to receive reflected light corresponding to an image in the root direction of the finger from the joint (first joint), an imaging element having sensitivity only to infrared light may be used. Even if two types of imaging elements are provided in the imaging device 5, it is possible to take an image similar to that provided with two types of filters.

Alternatively, after imaging reflected light in which visible light and infrared light are mixed by the imaging device 5 using an imaging device having sensitivity from visible light to infrared light, the distal interphalangeal joint ( The infrared light component may be removed from the image in the fingertip direction from the first joint), and the visible light component may be removed from the image in the finger base direction from the distal interphalangeal joint (first joint). Further, by applying black paint on the surface 13 of the finger authentication prism 1 or by sticking a blackboard on the surface 13, the contrast of the high contrast image in the fingertip direction from the distal interphalangeal joint (first joint) of the finger. May be further increased. Further, the reflective surface 12 may be mirror coated to increase the reflectance.

In this embodiment, the imaging device 5 is disposed below the imaging surface 11 of the finger authentication prism 1, but the present invention is not limited to this. In this embodiment, the finger authentication prism 1 of the biometric authentication device is arranged in the vertical direction. However, when the biometric authentication device is installed on the wall, the finger authentication prism 1 is arranged by being rotated 90 degrees. In this case, you may install the imaging device 5 in the position (for example, position of the horizontal direction of the imaging surface 11) which can image | photograph from the imaging surface 11 side of the finger authentication prism 1. FIG.

FIG. 9 shows a biometric authentication apparatus according to a modification of the present embodiment. In FIG. 9, a mirror 20 is arranged in the vicinity of the imaging surface 11 of the finger authentication prism 1 arranged in a direction rotated 90 degrees with respect to the imaging device 5. The reflected light of the finger 2 placed on the finger installation surface 10 of the finger authentication prism 1 passes through the imaging surface 11 and is incident on the mirror 20 that is rotated 90 degrees and reflected. The imaging device 5 is arranged so that an image taken on the mirror 20 can be taken. Thus, when the biometric authentication device is installed on the wall, the size of the biometric authentication device in the depth direction can be reduced.

Next, a fingerprint authentication device using the biometric authentication device according to the present invention will be described in detail. FIG. 10 is a configuration diagram of the fingerprint authentication device. FIG. 10 shows a finger authentication prism 1 installed in the longitudinal direction of the finger and a finger authentication prism 1 installed in the fingertip direction of the finger. The fingerprint authentication device includes an image processing unit 30, a verification unit 31, and a display unit 32 in addition to the biometric authentication device described above. The finger authentication prism 1 is arranged such that the finger installation surface 10 is arranged on the upper side and the longitudinal direction of the finger installation surface 10 coincides with the longitudinal direction of the finger 2. In addition, blood vessels present in the region between the distal interphalangeal joint (first joint) and the proximal interphalangeal joint (second joint) of the finger 2 are pressed by the finger placement surface 10 to inhibit blood flow. A finger placement unit 33 is provided so as not to be performed.

Further, the visible light source 3 and the infrared light source 4 are disposed below the finger authentication prism 1. A white light bulb or an LED can be used as the visible light source 3. As the infrared light source 4, a near-infrared light source having a wavelength of 700 nm to 1000 nm that absorbs oxyhemoglobin in blood well and has low sensitivity to biological pigments can be used.

The imaging device 5 is installed on the imaging surface 11 side of the finger authentication prism 1. The imaging device 5 is composed of an imaging device having sensitivity to visible light and near infrared light, and converts the light into a digital signal and outputs it. An image sensor composed of a CCD element or a CMOS can be used as the imaging element.

The infrared light component is removed from the reflected light at the position of the imaging surface 11 corresponding to the angle of view on the fingertip direction side with the distal interphalangeal joint (first joint) of the finger as the center of the angle of view of the imaging device 5. An infrared light cut filter 6 is installed. Further, the visible light component from the reflected light at the position of the imaging surface 11 corresponding to the angle of view on the finger base direction side with the distal interphalangeal joint (first joint) of the finger as the center of the angle of view of the imaging device 5. Infrared light transmission visible light cut filter 7 is installed.

The image processing unit 30 converts an image photographed by the imaging device 5 into a predetermined format and separates it into a high contrast image, a blood vessel pattern image, and a natural image. The high contrast image and the blood vessel pattern image are output to the collation unit 6, and the natural image is output to the display unit 7. Since the finger authentication prism 1 generates a trapezoidal distortion similar to the conventional triangular prism, the image processing unit 30 also corrects the trapezoidal distortion for a high contrast image.

The collation unit 31 inputs the high contrast image and the blood vessel pattern image from the image processing unit 30 and performs fingerprint collation. A known verification method can be used in the fingerprint authentication device. The display unit 32 receives and displays a natural image from the image processing unit 30. In this way, a criminal act that impersonates another person by using a finger forged with a resin such as silicon or pasting a semi-transparent fingerprint forged film with irregularities on the tip of the finger is displayed. The determination can be made based on 32 display images.

Next, the operation of the biometric authentication apparatus according to the embodiment of the present invention will be described. An individual finger 2 for biometric authentication is placed on the finger installation surface 10 of the finger authentication prism 1. In this state, visible light and infrared light are emitted from the visible light source 3 and the infrared light source 4 to the finger 2 through the imaging surface 11. Visible light and infrared light emitted from the visible light source 3 and the infrared light source 4 are reflected by the valley and ridge portions of the finger 2 placed on the finger installation surface 10 of the finger authentication prism 1.

Here, the refractive index of air is “1.0”, the refractive index of glass is “1.3” to “1.5”, and the refractive index of moisture and skin is “1.3” to “1.4”. is there. Due to the difference in the refractive index of the light, the reflected light of the valley portion of the finger 2 that enters the finger authentication prism 1 through the air layer cannot reach the reflecting surface 12. Only the reflected light coming directly from the finger placement surface 10 reaches the imaging surface 11.

On the other hand, the reflected light of the ridge portion of the finger 2 spreads in all directions in the finger authentication prism 1 and travels toward the reflecting surface 12 and the imaging surface 11. The reflected light of the ridge portion of the finger 2 facing the reflecting surface 12 is totally reflected and travels toward the imaging surface 11. That is, the reflected light of the ridge portion of the finger 2 propagates in the optical path from the finger installation surface 10 through the reflection surface 12 to the imaging surface 11.

In the imaging device 5, the reflected light that has passed through the imaging surface 11 is imaged, but the reflected light corresponding to the part in the fingertip direction from the distal interphalangeal joint (first joint) of the finger is an infrared light cut filter. 6 to receive light. On the other hand, reflected light corresponding to a portion in the finger base direction from the distal interphalangeal joint (first joint) of the finger is received via the infrared light transmitting visible light cut filter 7.

As described above, the imaging device 5 captures three types of images. That is, a high-contrast image of a part from the distal interphalangeal joint (first joint) to the fingertip direction, a natural image of a part of the finger from the distal interphalangeal joint (first joint) to the fingertip, FIG. 6 is a blood vessel pattern image of a portion in the direction from the distal interphalangeal joint (first joint) to the root of the finger.

FIG. 11 shows an example of an image taken by the imaging device 5 of the fingerprint authentication device. In the image of FIG. 11, the upper left image is a high-contrast image corresponding to the fingerprint part of the finger, the lower left image is a natural image including the fingerprint part, and the lower right image is the distal finger of the finger. It is a defect pattern image of the site | part of the root direction of a finger | toe from an internode joint (1st joint). The upper right image is a high-contrast image of a portion of the finger from the distal interphalangeal joint (first joint) to the base of the finger, but the finger placement unit 33 is placed on the finger placement surface 10, so Since the part of the finger from the distal interphalangeal joint (first joint) to the root direction of the finger is not in contact with the finger installation surface 10, it is not photographed by the imaging device 5 like the valley portion of the finger.

The image processing unit 30 separates the image acquired from the imaging device 5 into a high-contrast image, a blood vessel pattern image, and a natural image, and outputs the high-contrast image and the blood vessel pattern image to the collating unit 31. 7 is output. The collation unit 31 performs collation / authentication of the fingerprint and the blood vessel pattern by extracting and collating the feature points from the high contrast image and the blood vessel pattern image.

Since the display unit 32 displays a natural image, the inspector can determine whether or not the fingerprint image has been obtained by visual observation using a forged fingerprint film or tape. As described above, the biometric authentication device according to the present embodiment uses a visible natural image for determining whether or not the image is obtained using a forged fingerprint film or tape, and a fingerprint portion for verification. Three types of images, that is, a contrast image and a blood vessel pattern image, can be acquired by a single imaging operation using one imaging device 5. In the present embodiment, a natural image having a sufficient size to detect forgery can be obtained.

The biometric authentication apparatus according to the present invention can be configured by hardware, but the biometric authentication function can also be realized by a computer program. In this case, the function and operation of this embodiment can be realized by a processor that reads and executes a program stored in the memory. The functions of this embodiment can also be realized by a computer program.

Finally, the above-described embodiments are illustrative and not limiting, and the present invention is not limited to the embodiments. The present invention encompasses modifications and design changes that do not depart from the scope of the invention as defined in the claims.

In the present invention, biometric authentication is performed by photographing a fingerprint or the like of a finger using a finger authentication prism, but the biometric authentication target is not limited to a finger, and an image of another part of the human body is captured. The present invention is also applicable to a biometric authentication system that performs biometric authentication.

DESCRIPTION OF SYMBOLS 1 Finger authentication prism 2 Finger 3 Visible light source 4 Infrared light source 5 Imaging device 6 Infrared light cut filter 7 Infrared light transmission visible light cut filter 10 Finger installation surface 11 Imaging surface 12 Reflecting surface 13 Surface 20 Mirror 30 Image processing unit 31 Verification unit 32 Display unit 33 Finger placement unit

Claims

A biometric authentication device comprising a finger authentication prism, an imaging device, a visible light source, and an infrared light source,
The finger authentication prism includes a finger installation surface on which a finger to be authenticated is placed, an imaging surface disposed opposite to and parallel to the finger installation surface, and a predetermined angle with respect to the finger installation surface and the imaging surface. A reflecting surface arranged,
The finger authentication prism is arranged so that the longitudinal direction of the finger installation surface coincides with the longitudinal direction of the finger,
Irradiation light from the visible light source and / or the infrared light source is incident on the imaging surface, propagates through the finger authentication prism, and is reflected by the finger placed on the finger installation surface. The reflecting surface is formed at a predetermined angle so as to be totally reflected and reach the imaging surface,
The imaging device is disposed in proximity to the imaging surface of the finger authentication prism, and irradiation light from the visible light source and / or the infrared light source is reflected by a finger on the finger installation surface and directly onto the imaging surface. Imaging is performed based on the reflected light that has passed through the first optical path that reaches and the reflected light that has passed through the second optical path in which the irradiation light reaches the imaging surface from the finger installation surface through the reflective surface. Biometric authentication device.
In the imaging apparatus, the reflected light arriving via the first optical path and the reflected light arriving via the second optical path are reflected by the finger placed on the finger installation surface as the irradiation light of the visible light source is reflected. And imaging the reflected light corresponding to the part of the fingertip direction from the joint between the distal phalanges of the finger,
In the imaging apparatus, the reflected light arriving through the first optical path and the reflected light arriving through the second optical path are reflected by the finger placed on the finger installation surface by the irradiation light of the infrared light source. The biometric authentication device according to claim 1, wherein reflected light corresponding to a portion in a finger base direction from a distal interphalangeal joint of a finger is imaged.
An infrared light cut filter that removes infrared light from reflected light corresponding to a part in the fingertip direction from the joint between the distal interphalangeal joints of the finger is attached to the imaging surface,
The biometric authentication device according to claim 2, wherein a visible light cut filter that removes visible light from reflected light corresponding to a portion in a finger root direction from a joint between distal phalanges of a finger is attached to the imaging surface.
The imaging device includes a first imaging element having sensitivity to visible light in order to receive reflected light corresponding to a part in a fingertip direction from a distal interphalangeal joint of a finger;
3. A second imaging device having sensitivity to infrared light for receiving reflected light corresponding to a portion in the root direction of the finger from a joint between the distal phalanges of the finger. Biometric authentication device.
The infrared light component is removed from the image corresponding to the region in the fingertip direction from the distal interphalangeal joint imaged by the imaging device, and the distal interphalangeal joint imaged by the imaging device is removed. The biometric authentication apparatus according to claim 2, further comprising an image processing unit that removes a visible light component corresponding to a part in a finger base direction.
2. The finger authentication prism according to claim 1, wherein the finger authentication prism includes a surface that is formed perpendicular to the finger installation surface and the imaging surface and is disposed to face the reflection surface, and at least a part of the surface is black. Biometric authentication device.
The biometric authentication device according to claim 1, wherein a mirror coat is applied to the reflecting surface of the finger authentication prism.
The imaging device shoots a natural image based on reflected light that is incident through a first optical path after the irradiation light of the visible light source and / or the infrared light source is reflected by a finger on the finger installation surface, The biometric authentication device according to claim 1, wherein a contrast image is captured based on reflected light incident through the second optical path.
A finger placement surface on which a finger to be authenticated is placed, an imaging surface disposed opposite to and parallel to the finger placement surface, and a reflection surface disposed at a predetermined angle with respect to the finger placement surface and the imaging surface A finger authentication prism having a trapezoidal shape in side view,
A first optical path that directly reaches the imaging surface after the visible light and / or infrared light is irradiated and propagated on the imaging surface and reflected by a finger placed on the finger installation surface; A finger authentication prism in which the reflecting surface is formed at a predetermined angle so as to secure a second optical path that is totally reflected from the surface by the reflecting surface and reaches the imaging surface.
An infrared light cut filter that removes infrared light from reflected light corresponding to a part in the fingertip direction from the joint between the distal interphalangeal joints of the finger is attached to the imaging surface,
The finger authentication prism according to claim 9, wherein a visible light cut filter that removes visible light from reflected light corresponding to a portion in a finger root direction from a joint between distal phalanges of a finger is attached to the imaging surface.
10. The finger authentication prism according to claim 9, further comprising a surface that is formed perpendicular to the finger installation surface and the imaging surface and that is disposed to face the reflecting surface, and at least a part of the surface is black.
10. The finger authentication prism according to claim 9, wherein a mirror coat is applied to the reflecting surface.
A finger placement surface on which the finger to be authenticated is placed, an imaging surface disposed opposite to and parallel to the finger placement surface, and the reflected light is totally reflected after reaching the imaging surface after being reflected by the finger placement surface A biometric authentication method using a finger authentication prism including a reflective surface arranged at a predetermined angle with respect to the finger installation surface and the imaging surface,
A first optical path for directly reflecting light reflected by the finger placed on the finger installation surface when the imaging surface is irradiated with visible light and / or infrared light; and the finger installation surface Branched to a second optical path that reaches the imaging surface via the reflective surface,
Of the reflected light that has passed through the first optical path and the reflected light that has passed through the second optical path, the first image is taken based on the reflected light corresponding to the part in the fingertip direction from the distal interphalangeal joint of the finger,
Of the reflected light that has passed through the first optical path and the reflected light that has passed through the second optical path, a second image is photographed based on the reflected light corresponding to the part in the root direction of the finger from the joint between the distal interphalangeal joints of the finger. A biometric authentication method.