JP2004255212A - Characteristic pattern detection apparatus of finger and individual identification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information pattern detection apparatus which detects the vein pattern of a person with high precision without the effect of stain, wrinkles and so on. <P>SOLUTION: Light from a finger 11 is split into visible light and near-infrared light by a dichroic mirror 13-1, and falls on a lens 15. The near-infrared video picture and visible light video picture of the finger 11 are obtained by a CCD imaging device 16-1. From these both video pictures, an unwanted pattern of the near-infrared video picture is eliminated by an operational equipment 17-1 of a control device, and a blood vessel picture of the finger is obtained. Personal identification is conducted by checking the blood vessel picture registered in a data base 18-1 against an obtained picture. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a personal characteristic pattern detecting device, and more particularly, to a device for detecting a characteristic of a living body possessed by a person, for example, a blood vessel pattern, and a personal identification device for identifying an individual using the device.

  2. Description of the Related Art Conventionally, identification of an individual is mainly performed when giving permission to use a bank terminal or a computer, or managing entry into a room where the number of visitors is restricted. In these cases, a method using a password has been mainly used for personal identification. However, recently, technology for performing personal identification using characteristics of a living body has been developed.

  As one of them, a method using a vein blood vessel pattern on the back of the hand is disclosed in Patent Document 1 below, and a personal identification device using a vein blood vessel pattern on the finger is disclosed in Patent Document 2 described below (Japanese Patent Application Laid-Open No. 7-21373). ).

UK Patent No. 2156127B

Published patent publication (Japanese Patent Laid-Open No. 7-21373)

  Those using a venous blood vessel pattern have the advantage that theft or forgery is difficult, which increases safety. The personal identification device using a venous blood vessel pattern disclosed in the above-mentioned published patent publication (Japanese Patent Application Laid-Open No. 7-21373) measures the intensity of transmitted light or reflected light of a hand or finger using near infrared rays. It describes that only a vein blood vessel pattern can be detected by using near infrared rays.

  However, it has been found that measurement conditions, for example, the type of light source, or measurement environment, for example, disposition of a finger on the device, and unnecessary patterns that interfere with identification other than vein patterns due to dirt or wrinkles of hands and fingers are generated. Was. If a pattern other than a vein pattern is used as personal information, the individual is judged to be not legitimate even though the individual is correct. Becomes impossible.

Accordingly, a main object of the present invention is to realize a personal characteristic pattern detection device that accurately detects a venous blood vessel pattern of an individual.
Another object of the present invention is to provide a personal identification device using a vein pattern, which prevents the effects of finger dirt and wrinkles, and enhances identification accuracy.

In order to achieve the above object, a personal characteristic pattern detecting apparatus according to the present invention includes a first image capturing unit that obtains a first image by light transmitted through a subject such as a human finger, and a first image capturing unit that obtains a first image by reflected light from the subject. A second image capturing means for obtaining a second image, and an arithmetic processing unit for obtaining a blood vessel image of the subject using the signals of the first and second images to remove unnecessary patterns of the first image. Constitute.
In a preferred embodiment of the present invention, near-infrared light is used as a light source for obtaining light transmitted through the subject, and a visible light source is used as a light source for obtaining the reflected light.

  According to the present invention, since the near-infrared light has a high transmission rate through the living body, the irradiation light spreads inside the finger while being scattered by the living tissue of the finger, and further transmits from the finger surface to the outside of the finger. . At this time, if there is a venous blood vessel near the surface of the finger, the near-infrared light is absorbed by hemoclobin in the venous blood vessel, and a shadow of the venous blood vessel is projected on the surface of the finger. Therefore, the image of the vein blood vessel projected on the surface of the finger together with wrinkles and dirt on the surface of the living body is captured in the image captured by the first image capturing unit using the near-infrared light. On the other hand, visible light is largely absorbed by the living tissue of the finger, and most of the light that enters the living body is absorbed and does not pass outside. Therefore, the image of the living body surface reflected light does not show the shadow of the vein blood vessel inside the finger, but captures the shape, dirt, wrinkles, and the like of the finger. Therefore, from the near-infrared transmitted light image of the finger on which dirt and the like are shown together with the venous blood vessels, the influence of the dirt and the wrinkle is removed by the arithmetic processing means using the image of the dirt and the wrinkle of the finger surface by the visible light image. The detected feature pattern is detected.

  When the personal characteristic pattern detection device of the present invention is applied to a personal identification device, the high-precision personal characteristic pattern of the present invention can be used, and high-precision personal identification can be performed. When applied to a personal identification device, it is desirable to detect a vein blood vessel pattern of a finger from the viewpoint of simplification of a detection device and improvement of accuracy in a living body.

<Embodiment 1>
FIG. 1 is a block diagram showing an embodiment of a personal identification device using a personal characteristic pattern detecting device according to the present invention. The configuration and basic operation of the device will be described.
The personal characteristic pattern detection device detects a vein pattern of a finger 11 as a subject. The personal characteristic pattern detection device includes an LED 12-1 as a light source that irradiates near-infrared light from the side of the finger 11 having the nail, and two light sources that irradiate visible light from the side opposite to the side of the finger 11 having the nail. LEDs 12-2 and 12-3, an interface for controlling lighting of the LEDs 12-1 to 3 by the control device 17, a dichroic for separating near-infrared light transmitted through the finger 11 and visible light reflected by the finger. A mirror 13-1 and a reflecting mirror 14-1; a lens 15 for forming an image of the finger by near-infrared transmitted light of the finger and an image of the finger by visible light; The CCD imaging device 16-1 for converting the image and the near-infrared light image into a video electric signal, the monitor 16-2 for confirming the image of the finger photographed by the CCD imaging device 16-1 as a video, and the above devices are controlled. And process image signals. It consists of the control device 17 for. Control device 1
Reference numeral 7 denotes a microprocessor, which has an operation unit 17-1 therein and performs signal processing such as removal of an unnecessary pattern described later.

  The dichroic mirror 13-1 is a mirror that transmits near-infrared light and reflects visible light. Near-infrared light transmitted through the finger 11, visible light reflected by the finger, and the like enter the dichroic mirror 13-1. Of the incident light, near-infrared light passes through the dichroic mirror 13-1 and enters the lens 15. The visible light is reflected by the dichroic mirror 13-1, is further reflected by the reflecting mirror 14-1, is separated from the near-infrared light, and enters the lens 15 from another direction.

  In FIG. 1, an input device 18-1, such as an individual ID number and a password, is controlled by the control device 17 to constitute a personal identification device, a memory device 18-2 for storing an image of the finger 11, and a registration device. And a database 18-3 for storing the obtained personal information.

  Next, the operation of the personal characteristic pattern detection device and the personal identification device will be described with reference to the flowchart of FIG. First, in a state where this device has started operation, a person who wants to access this device inputs an ID number and a password using the data input device 18-1. Next, the LEDs 12-1, 12-2, and 12-3, which are light sources, are turned on. An image of the finger 11 illuminated by the light source is formed by the lens 15 and converted into an electric signal by the CCD imaging device 16-1. The near-infrared image and the visible light image converted into the electric signal are temporarily stored in the memory device 18-2.

Next, the control device 17 performs image processing for vein pattern extraction using the visible light image and the near-infrared light image. This image processing is performed according to the following process.
The image stored in the memory device 18-2 includes a near-infrared image and a visible light image in one image data. Therefore, in order to make correspondence between the near-infrared image and the visible light image that represent the same point on the surface of the finger, differentiation processing of the near-infrared image and the visible light image is performed. Extract the outline of the video. Next, one of the two contour lines is superposed on the other by rotating and translating. The pixels of the near-infrared image and the pixels of the visible light image are associated with each other by using the translation amount and the rotation angle at this time. Therefore, normalization correction is performed on the pixel intensity of the near-infrared image by dividing the signal intensity of the pixel of the near-infrared image by the signal intensity of the corresponding pixel of the visible light image.

  In the image subjected to the normalization correction, attention is paid to the signal intensities of the pixels in the part where the vein is shown and the part where the vein is not shown. First, since the near-infrared light scattered and transmitted through the finger 11 is absorbed by the vein blood vessels near the finger surface in the portion where the vein of the near-infrared image is reflected, the brightness of the pixel in the vein portion becomes dark, The signal strength has a small value. On the other hand, the pixel signal intensity of the same part of the visible light image is determined by the intensity of the light reflected from the same part of the surface of the illumination light. Since the light reflected by the surface is not absorbed by the veins inside the finger, it does not have a small value such as the intensity due to the transmitted light. Therefore, the value after normalization correction obtained by dividing the transmitted light intensity signal by the reflected light intensity signal becomes a small value.

  A portion common to the near-infrared image and the visible light image is displayed in a portion where the vein is not shown, such as dirt and wrinkles of a finger. When there is no dirt, neither transmitted light nor reflected light is absorbed, and both have the same brightness. When there is dirt, the intensity of both the transmitted light and the reflected light is attenuated due to absorption by the dirt. Therefore, the brightness of the pixel in the portion where the vein is not reflected is not extremely dark in either the near-infrared image or the visible light image. As a result, the pixel signal intensity after normalization correction of the portion where the vein is not reflected has substantially the same value whether or not there is dirt.

  Accordingly, while the normalization correction keeps the signal intensity of the vein portion at a small value, the signal intensity of the portion other than the vein portion is converted to substantially the same value, so that the vein portion is emphasized on the image. A vein pattern is extracted by further binarizing the image after the normalization correction. The control device 17 performs image processing including the above-described series of processes, and further performs the following feature extraction processing on the obtained binarized image of the venous blood vessel pattern.

  FIG. 3 is a vein blood vessel pattern diagram of a finger. In FIG. 3, reference numeral 31 denotes a contour of the finger obtained by differentiating the finger image. 32 and 33 are lines representing veins. Reference numeral 34 denotes the center line of the outline of the finger. The point of intersection between the center line 34 of the finger and the tip of the contour 31 of the finger is defined as point P. Let y be the interval between the point X at a distance x from the point P at the tip of the finger toward the palm and the intersection of a line drawn from the point X in a direction perpendicular to the center line and the vein line. When the distance x from the tip of the finger changes, the value of the interval y from the center line to the vein line changes, so the vein pattern is quantified as a curve Y (x) using x as a variable. The curve Y (x) is used as a vein feature. The characteristic amount of the vein line on one side with respect to the center line 34 is Y1 (x), and the characteristic amount of the venous line on the opposite side is Y2 (x).

  When there are a plurality of vein lines, an interval from the center line to each vein may be obtained, and a function representing a feature amount may be set for each vein. Alternatively, the sum of the intervals from the center line to each venous line may be calculated, and the sum may be used as the value of the feature amount corresponding to x.

  Next, an input instruction of whether to execute the registration process or the access is issued to the access applicant, and the input is awaited. When the input from the access applicant is a registration, the information of the personal characteristic pattern detecting device is stored in the database 18-3. In the case of access execution, the characteristic information of the blood vessel image stored in the memory device 18-2 and the characteristic information of the blood vessel image corresponding to the ID number and the password input first are extracted from the database 18-3, and the two are compared. .

As a result of the comparison, if the measured data matches the registered data, a device access permission signal is issued, and then the latest feature pattern is stored in the database 18-3. If they do not match, a non-permission signal is issued. In this personal identification device, since the photographing directions for capturing the near-infrared light image and the visible light image of the finger are the same, the outer shape image of the finger is exactly the same for the near-infrared light image and the visible light image. Thus, image processing for obtaining a blood vessel image can be performed with high accuracy.
<Embodiment 2>
FIG. 4 is a block diagram showing a second embodiment of the personal identification device using the personal characteristic pattern detecting device according to the present invention.
In this embodiment, an image guide 21-1 is further incorporated in the apparatus shown in FIG. Although FIG. 1 shows an optical system configuration in which reflected light or transmitted light from a finger is directly incident on the dichroic mirror 13-1, in the present embodiment, visible light or near-infrared light from the finger 11 is transmitted. The light enters the dichroic mirror 13-2 through the image guide 21-1.

   More specifically, light incident on the lens 22-1 from the finger 11 is imaged on the end face of the image guide 21-1 by the lens 22-1. The image guide 21-1 transmits the image to the opposite end face. The transmitted light is further incident on the dichroic mirror 13-2 by the relay lens 23-1.

The light incident on the dichroic mirror 13-2 is separated into visible light and near-infrared light, and the lens 15 and the CCD element 16-1 convert the near-infrared light image and the visible light image of the finger into electric signals. The configuration and operation other than this part are the same as those of the first embodiment. In the case of FIG. 1, the light from the finger must directly enter the dichroic mirror 13-1. Therefore, the entire imaging device including the dichroic mirror 13-1, the reflecting mirror 14-1, the lens 15, and the CCD 16-1 must be installed in a position and a direction where light from the finger 11 can directly enter the dichroic mirror 13-1. Was. However, in the present embodiment, since the image guide 21-1 is made of an optical fiber and has flexibility, the position and the direction of the lens 22-1 may be fixed so that light from a finger enters, and the reflecting mirror is used. The imaging device 16-1 including the lens 14-2, the lens 15, and the CCD imaging tube can be arranged at an arbitrary position and an arbitrary direction with respect to the finger. Therefore, the degree of freedom in the device configuration is increased, and the entire device can be configured compactly.
<Embodiment 3>
FIG. 5 is a block diagram showing a third embodiment of the personal identification device using the personal characteristic pattern detecting device according to the present invention. In the present embodiment, the image guide 21-1 used in the second embodiment is configured by using two image guides 21-2 and 21-3.

The blood vessel image projected on the surface of the finger 11 by the near-infrared light transmitted through the finger 11 is distributed over the entire surface of the finger. For this reason, there is a restriction that only a part of the blood vessel pattern of the finger 11 can be used when viewed from one direction as shown in FIG. Therefore, in the present embodiment, two image guides 21-2 and 21-3 are used, and the finger 11 can be measured from two directions, so that a blood vessel pattern on the finger surface over a wider range can be imaged. Things. Actually, light source LEDs 12-4 and 12-2, 12-3 and 12-5 are provided on both sides of each image guide 21-2 and 21-3 so that the brightness of the image measured by each optical fiber becomes uniform. Are placed.
The operation of this embodiment is the same as that of the first embodiment. In this embodiment, two image guides are used, but more image guides may be used.
<Embodiment 4>
FIG. 6 is a block diagram showing a fourth embodiment of the personal identification device using the personal characteristic pattern detecting device according to the present invention. The present embodiment is obtained by removing the dichroic mirror and the reflecting mirror arranged on the input side of the lens 15 from the apparatus configuration of the first embodiment, and simplifying the optical means. That is, in the present embodiment, the necessary video imaging can be performed without using a dichroic mirror by performing the shooting of the near infrared light video and the shooting of the finger video using visible light with a time lag. That is, first, the near-infrared light source 12-3 is turned on to photograph an image of the finger with near-infrared light, and then the near-infrared light source 12-3 is turned off, and the visible light sources 12-1 and 12- 2 is turned on, and an image of the finger is taken with visible light. Image processing for obtaining a blood vessel image is performed using the near-infrared light image and the visible light image captured in this manner. Other configurations and operations thereafter are the same as those in the first embodiment. The order of photographing the visible light image and the near infrared light image may be reversed. The switching of the photographing time may be controlled manually or may be controlled by the control device 17 so as to be automatically switched.

1 is a block diagram illustrating an embodiment of a personal identification device using a personal characteristic pattern detection device according to the present invention. Operation flow diagram of the apparatus of FIG. Illustration of finger blood vessel pattern 2 is a block diagram showing a second embodiment of the personal identification device using the personal characteristic pattern detection device according to the present invention. 3 is a block diagram showing a third embodiment of the personal identification device using the personal characteristic pattern detection device according to the present invention. 3 is a block diagram showing a third embodiment of the personal identification device using the personal characteristic pattern detection device according to the present invention.

Explanation of reference numerals

11 finger, 12-1 near-infrared light LED, 12-2 to 3 ... visible light LED,
13-1-4: dichroic mirror, 14-1-4: reflecting mirror,
15: lens, 16-1: CCD imaging device, 16-2: monitor,
17 ... control unit, 17-1 arithmetic unit, 18-1 ... data input unit,
18-2: memory, 18-3: database,
19-1 ... 2 ... Interface, 21-1-4 ... Image guide,
22-1 to 4 ... lenses, 23-1 to 4 ... lenses.

Claims (12)

  First image capturing means for obtaining a first image by light transmitted through the subject; second image capturing means for obtaining a second image by reflected light from the subject; An individual characteristic pattern detecting device, comprising: an arithmetic processing device for obtaining unnecessary blood vessel images of the subject by removing unnecessary information of a first image using a signal.   The personal characteristic pattern detecting device according to claim 1, wherein the light source of the first image capturing means is a near-infrared light source, and the light source of the second image capturing means is a visible light source.   3. The personal characteristic pattern detecting device according to claim 1, wherein the subject is a finger. 4. The individual according to claim 1, further comprising an optical unit having a dichroic mirror, a lens, and a reflecting mirror for separating the transmitted light and the reflected light and leading them to the first image capturing unit and the second image capturing unit, respectively. Feature pattern detection device.   5. The personal characteristic pattern detecting device according to claim 4, wherein a light guide is provided on an incident side of said optical means.   6. The personal characteristic pattern detecting device according to claim 1, wherein at least one of the first and second image capturing means has a plurality of light sources having different irradiation positions.   7. The personal characteristic pattern detecting device according to claim 1, wherein an LED element is used as the light source.   7. The personal characteristic pattern detecting device according to claim 1, wherein the means for converting the transmitted light and the reflected light of the first and second image pickup means into an image is constituted by a CCD image pickup device.   The personal characteristic pattern detecting device according to any one of claims 1 to 6, wherein the arithmetic processing device has a calculating unit that extracts a coordinate value of each point of the blood vessel image as a personal characteristic pattern.   A method for detecting a vein pattern of a finger, which irradiates the finger with near-infrared light from a near-infrared light source and visible light from a visible light source and reflects the image by the near-infrared light transmitted through the finger and the finger A vein pattern detection method comprising: obtaining an image formed by visible light, and performing an arithmetic process for removing unnecessary patterns of the image formed by near infrared light by using the image formed by visible light.   The vein pattern detection method according to claim 10, wherein the irradiation of the infrared light from the near-infrared light source and the irradiation of the visible light from the light-visible light source are performed in different time zones.   An individual identification method for identifying an individual by comparing a vein pattern detected by the vein pattern detection method according to claim 10 with a previously stored vein pattern.

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