JP5268997B2 - Biometric authentication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in which a uniform brightness required for a high-quality image cannot be obtained across the whole imaging area, making it difficult to perform appropriate personal authentication, if only one of first infrared LED 2 and second infrared LED 4 is used for illumination as in a conventional technique. <P>SOLUTION: The biometric authentication device used for authentication using a vein image of an organism comprises: a mounting surface on which an organism is placed when a vein image is taken; a plurality of light sources which illuminates the organism placed on the mounting surface with infrared light; an imaging unit which takes a vein image of the organism with light from the plurality of light sources; and an image processing unit which processes the vein image taken by the imaging unit. The plurality of light sources and the imaging unit are provided on the same side as the organism placed on the mounting surface, and the plurality of light sources is provided on the same side as the imaging unit. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to an authentication apparatus for authenticating an individual, and more particularly to a technique for performing authentication using vein information of a living body.

  In recent years, an apparatus for authenticating a vein of a living body and performing personal authentication has been developed. For example, Patent Document 1 is an example of a finger vein authentication device. Patent Document 1 states that “in order to absorb a positional shift that occurs when a living body is presented, a plurality of registered data with different imaging positions are obtained by presenting the living body multiple times, thereby providing high authentication accuracy and The purpose is to provide a small and flat vein authentication device ”, and as a means for solving the problem,“ the living body information processing apparatus of the present invention includes a mounting surface on which a living body is placed, a light source that irradiates light on the living body, An imaging unit that captures light transmitted through the living body and obtains a registered image candidate; and a processing unit that extracts a blood vessel pattern from the captured plurality of registered image candidates and sets it as a registered pattern. After acquiring the registered image, it is detected whether the living body has moved away from the placement surface, and an image captured by the imaging unit after being placed on the placement surface again is set as the registered image candidate. ” Is (summary see Patent Document 1).

  Here, FIG. 1 is a schematic diagram showing a configuration of a conventional finger vein authentication apparatus, FIG. 2 is a conventional vein image, and FIG. 3 is a schematic diagram showing an example of a conventional luminance distribution. The conventional method shown in FIG. 1 is a system that reduces the size of the apparatus in the height direction by providing a light source and a detector on the same side with respect to a living body to be measured without providing a light source on the side surface of the finger. (For example, Patent Document 1). In such a conventional system, for example, as shown in FIG. 1, the first infrared LED 2 and the second infrared LED 4 are arranged in the fingertip direction and the finger base direction with the imaging unit 3 interposed therebetween. In this method of reducing the size of the apparatus in the height direction, a luminance distribution as shown in FIG. 3 is obtained by irradiating both the LEDs 2 and 4 with optimum brightness, and a high-quality image area 7 is obtained. It can be obtained over the entire imaging area.

JP 2008-181570 A

  In the conventional structure of FIG. 1, the first infrared LED 2 and the second infrared LED 4 are arranged in the fingertip direction and the fingertip direction with the imaging unit 3 interposed therebetween. Here, when only one of the first infrared LED 2 and the second infrared LED 4 in the conventional method of FIG. 1 is irradiated, the uniform brightness necessary to obtain a good quality image in the entire imaging region is obtained. Therefore, it is difficult to properly perform personal authentication. Therefore, in the said conventional system, either one of 1st infrared LED2 and 2nd infrared LED4 cannot be deleted from an apparatus, but the subject that the further miniaturization of an apparatus was difficult occurred.

  In the present invention, in order to improve the above problem, the configuration described in the claims is used as an example. Specifically, for example, a biometric authentication device that performs authentication using a vein image of a living body, and a placement surface on which a living body is placed when a vein image is captured, and a living body placed on the placement surface are infrared A plurality of light sources that emit light, an imaging unit that captures a vein image of the living body using light emitted from the plurality of light sources, and an image processing unit that processes the vein image captured by the imaging unit The plurality of light sources and the imaging unit are provided on the same side with respect to the living body installed on the mounting surface, and the plurality of light sources are provided on the same side with respect to the imaging unit. A biometric authentication device characterized in that it is used is used.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in authentication performance and can provide a small-sized biometric authentication apparatus.

1 is a diagram illustrating an example of a conventional biometric authentication device The figure which shows an example of the vein image of the conventional system A diagram showing an example of the luminance distribution of the conventional method The figure which shows an example of the biometrics authentication apparatus in a present Example The figure which shows an example of the vein image at the time of the primary imaging in a present Example The figure which shows an example of the vein image at the time of the secondary imaging in a present Example The figure which shows an example of the synthesized image of the primary imaging and secondary imaging in a present Example The figure which shows an example of the luminance distribution in a present Example

  FIG. 4 shows a configuration example of the biometric authentication apparatus in the present embodiment.

  In this embodiment, a case where a finger vein image is acquired and personal authentication is performed will be described as an example. However, the present invention is not limited to this, and can also be applied to a personal authentication apparatus that captures a vein image with respect to another living body (for example, a palm or the like) with the same apparatus configuration.

  In FIG. 4, a first infrared LED 2 and a second infrared LED 4 are light sources that irradiate the finger 1 placed on the placement surface 11 with infrared light. The imaging unit 3 captures a vein image of the finger 1 using infrared light emitted from the first infrared LED 2 or the second infrared LED 4. That is, the infrared light is transmitted and scattered by the finger 1, and the imaging unit 3 detects the light and images a finger vein image. The vein image captured by the imaging unit 3 is subjected to a predetermined process by the image processing unit 10 and a personal authentication process is performed.

  In the apparatus of this embodiment, the infrared LEDs 2 and 4 and the imaging unit 3 are provided on the same side with respect to the finger 1 installed on the placement surface 11. That is, the infrared LEDs 2 and 4 are different from the method of irradiating infrared light from the side surface side or the upper side of the finger, and infrared light is directed toward the finger 1 from the lower side (that is, the same side as the imaging unit 3). It is a method to irradiate. This method makes it possible to reduce the size of the apparatus in the height direction, but on the other hand, it is necessary to obtain an appropriate luminance distribution over the entire imaging region.

  Therefore, in the biometric authentication device in the present embodiment, the first infrared LED 2 and the second infrared LED 4 are mounted on the fingertip side of the finger 1 with respect to the imaging unit 3. The second infrared LED 4 is provided at a position closer to the imaging unit 3 than the first infrared LED 2. Here, in this embodiment, an example in which the infrared LEDs 2 and 4 are mounted on the fingertip side of the finger 1 with respect to the imaging unit 3 will be described, but the present invention is not limited to this, and the infrared LEDs 2 and 4 What is necessary is just the structure provided in the same side with respect to the imaging part 3. FIG. That is, a configuration in which the infrared LEDs 2 and 4 are provided on the base side of the finger 1 or on one side of the side surface of the finger 1 with respect to the imaging unit 3 may be employed.

  Next, the flow of vein image capturing processing in this embodiment will be described with reference to FIGS. First, the first infrared LED 2 is irradiated to acquire an image of the fingertip side half as shown in FIG. Next, in order to acquire an image on the finger base side, the luminance of the first infrared LED 2 is increased, and a vein image at the time of secondary imaging shown in FIG. 6 is acquired. At this time, since the luminance of the first infrared LED 2 is insufficient in most cases in the vein image at the time of secondary imaging, the second infrared LED 4 is irradiated to compensate for the luminance, and an image with a good quality of the finger half side is obtained. Each vein image at the time of primary imaging and at the time of secondary imaging is processed by the image processing unit 10. Then, the finger vein image obtained by the primary imaging and the finger vein image obtained by the secondary imaging are combined as one finger vein image information as shown in FIG. Done.

  Next, the effect of the present embodiment will be described in terms of luminance distribution. FIG. 8 is a diagram illustrating an example of the luminance distribution of vein images obtained by primary imaging and secondary imaging. Since the sensor allowable amount of the imaging unit 3 is determined within a finite range (range), in order to obtain an appropriate vein image, the luminance distribution should be within the range of the sensor allowable amount over the entire imaging region. Need to be adjusted. That is, if the brightness of the infrared light emitted from the light source is too high in a certain imaging area, the sensor allowable amount of the imaging unit 3 is exceeded and saturation occurs, so that an appropriate vein image cannot be obtained. On the other hand, even if the luminance to be irradiated is too small, the sensor of the imaging unit 3 cannot detect infrared light, and thus cannot obtain an appropriate vein image.

  For example, at the time of primary imaging, the brightness is within the image area 7 with good quality (that is, within the sensor allowable range) in the upper half area of the imaging area 8, but the lower half area of the imaging area 8. It can be seen that in the region of (2), the luminance value of the infrared light is insufficient and an appropriate vein image cannot be obtained. Therefore, at the time of secondary imaging, the infrared LEDs 2 and 4 are controlled so that the luminance value is appropriate for the lower half area. That is, at the time of secondary imaging, the second infrared LED 4 is irradiated so as to increase the luminance of the first infrared LED 2 and further compensate the luminance value of the lower region. As a result, the luminance distribution during the secondary imaging should be such that the luminance is within the image area 7 with good quality (that is, within the sensor allowable range) in the lower half of the imaging area 8. it can.

  At the time of secondary imaging, luminance saturation occurs in the upper region, and an appropriate vein image cannot be obtained. However, the luminance saturated region is an image region 7 with high quality at the time of primary imaging (that is, luminance The problem is solved because the distribution overlaps the region (within the appropriate range). That is, by combining the primary captured image and the secondary captured image captured in this way, the problem of the sensor tolerance of the imaging unit 3 is solved, and an appropriate vein image is obtained over the entire imaging region. Can do.

  Further, if the brightness does not become insufficient, the use of only the first infrared LED 2 can obtain an image with less change in the brightness value in the imaging region 8, so the second infrared LED 4 is used to compensate for the brightness shortage. If an auxiliary role is used and irradiation is performed as necessary, it can be expected to obtain a higher quality image.

  As another example of the embodiment, the first infrared LED 2 is used at the time of primary imaging and the second infrared LED 4 is used at the time of secondary imaging depending on the situation of the luminance distribution, and each LED is primary and secondary. A method of controlling exclusively by imaging may be used.

  According to the above-described embodiment, it is possible to provide a small-sized biometric authentication device that has excellent authentication performance. That is, by gathering infrared LEDs on one side with respect to the imaging unit 3, the device can be reduced in size in the surface direction by reducing the other space. Furthermore, even in that case, according to the present embodiment, an appropriate vein image can be obtained, and a small biometric authentication device excellent in authentication performance can be provided.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

1 ... finger 2 ... first infrared LED
3 ... Imaging unit 4 ... Second infrared LED
5 ... Luminance saturated region 6 ... Luminance deficient region 7 ... Good quality image region 8 ... Luminance region 9 ... Camera 10 ... Image processing unit 11 ... Mounting surface

Claims (2)

A biometric authentication device that performs authentication using a vein image of a living body,
A mounting surface on which a living body is placed when capturing a vein image;
A plurality of light sources for irradiating the living body placed on the mounting surface with infrared light;
An imaging unit that captures a vein image of the living body with light emitted from the plurality of light sources;
An image processing unit that processes the vein image captured by the imaging unit,
The plurality of light sources and the imaging unit are provided on the same side with respect to the living body installed on the placement surface,
The plurality of light sources are provided on the same side with respect to the imaging unit ,
The plurality of light sources include at least a first light source and a second light source installed at a position closer to the imaging unit than the first light source,
The imaging unit captures a vein image of the living body multiple times,
The image processing unit performs a synthesis process on a plurality of vein images captured by the imaging unit,
Of the plurality of vein images captured by the imaging unit, the first vein image is captured by the light emitted from the first light source, and the second vein image is the first light source and the second light source. From the light source or the light emitted from the second light source,
The biometric authentication is characterized in that an irradiation intensity of the first light source when capturing the first vein image is smaller than an irradiation intensity of the first light source when capturing the second vein image. apparatus. The biometric authentication device according to claim 1 ,
The living body from which a vein image is taken is a finger,
The biometric authentication device, wherein the plurality of light sources are provided on a fingertip side of the living body with respect to the imaging unit.

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