JP4659691B2 - Feature pattern detector - Google Patents

Description

  The present invention relates to a personal feature pattern detection device, and more particularly to a device for detecting a biological feature of a person, such as a blood vessel pattern, and a personal identification device for identifying an individual using the device.

  Conventionally, identification of an individual is mainly performed when permission to use a bank terminal or a computer is given, or when entering a room with restrictions on the number of visitors. In these cases, a method using a password has been mainly used for personal identification. However, recently, development of a technique for performing individual identification using characteristics of a living body has been advanced.

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

British patent 2156127B Published patent publication (Japanese Patent Laid-Open No. 7-21373)

  Those using the venous blood vessel pattern have the advantage that safety is increased when theft and counterfeiting are difficult. In the personal identification device using the venous blood vessel pattern disclosed in the above-mentioned published patent publication (Japanese Patent Laid-Open No. 7-21373), the intensity of transmitted light or reflected light of the hand or finger is measured using near infrared rays. It is described that only a venous blood vessel pattern can be detected by using near infrared rays.

  However, it is understood that unnecessary patterns that obstruct the identification other than the vein pattern may occur depending on the measurement conditions, for example, the type of light source, or the measurement environment, for example, finger placement on the device, dirt on the hand or finger, and wrinkles. It was. When a pattern other than a vein pattern is used as personal information, it is determined that the individual is not a legitimate individual even though the individual is correct. Therefore, a personal identification device that requires a high degree of accuracy is practical. It becomes impossible.

Accordingly, a main object of the present invention is to realize an individual feature pattern detection apparatus that accurately detects an individual's venous blood vessel pattern.
Another object of the present invention is to provide a vein pattern-based personal identification device that prevents the effects of finger smudges and wrinkles, and has improved identification accuracy.

In order to achieve the above object, the personal feature pattern detection apparatus of the present invention includes a first image imaging means for obtaining a first image by light transmitted through a subject such as a human finger, and a first image obtained by reflected light from the subject. A second image capturing means for obtaining two images, and an arithmetic processing unit for obtaining a blood vessel image of the subject by removing the unnecessary pattern of the first image using the signals of the first and second images. 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 near infrared light has a high rate of transmitting through the living body, the irradiation light spreads inside the finger while being scattered by the biological tissue of the finger, and further passes from the surface of the finger to the outside of the finger. . At this time, if there is a venous blood vessel near the surface of the finger, near infrared light is absorbed by hemoglobin in the venous blood vessel, and a shadow of the venous blood vessel is projected on the surface of the finger. Therefore, the pattern of the venous blood vessel projected on the surface of the finger together with wrinkles and dirt on the surface of the living body is photographed in the image by the first image capturing means photographed using near infrared light. On the other hand, visible light is largely absorbed by the biological 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 venous blood vessel inside the finger, and the shape, dirt, wrinkles, etc. of the finger are photographed. Therefore, from the near-infrared transmitted light image of the finger that shows stains along with the venous blood vessels, the effect of the stain and wrinkles is removed by the arithmetic processing means using the image of the finger surface dirt and wrinkles by the visible light image The detected feature pattern is detected.

  When the personal feature pattern detection device of the present invention is applied to a personal identification device, the high-precision personal feature 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 that the finger vein blood vessel pattern is detected from the viewpoint of simplifying the detection device and improving accuracy in a living body.

<Embodiment 1>
FIG. 1 is a block diagram showing an embodiment of a personal identification device using a personal feature pattern detection device according to the present invention. The configuration and basic operation of the device will be described.
The personal feature pattern detection apparatus detects a vein pattern of the finger 11 as a subject. The personal feature pattern detection apparatus includes a light source LED 12-1 that emits near-infrared light from the side surface of the finger 11 with the nail and two light sources that emit visible light from the side surface opposite to the side surface of the finger 11 LEDs 12-2 and 12-3, an interface for controlling the 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 The mirror 13-1 and the reflecting mirror 14-1, the lens 15 that forms the finger image by the near-infrared transmitted light of the finger and the finger image by the visible light, and the formed visible light. The CCD imaging device 16-1, which converts an image and a near-infrared light image into a video electrical signal, the monitor 16-2 for confirming the image of a finger photographed by the CCD imaging device 16-1 as an image, and the above devices Or processing the image signal It consists of the control device 17 for. Control device 1
7 is constituted by a microprocessor, and has an arithmetic unit 17-1 therein to perform signal processing such as removal of unnecessary patterns 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, or the like is incident on the dichroic mirror 13-1. Of the incident light, near-infrared light passes through the dichroic mirror 13-1 and enters the lens 15. Visible light is reflected by the dichroic mirror 13-1, is further reflected by the reflecting mirror 14-1, is separated from near-infrared light, and enters the lens 15 from another direction.

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

  Next, operations of the personal feature pattern detection apparatus and the personal identification apparatus will be described with reference to the flowchart of FIG. First, in a state in which this device has started to operate, a person who wishes to access this device inputs an ID number and a password through 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 image pickup device 16-1. The near-infrared video and visible light video converted into electrical signals 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 video and a visible light video in one piece of video data. Therefore, in order to take correspondence between the near-infrared image point and the visible light image point that are the same point on the surface of the finger, the differential 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 superimposed on the other by translation and rotation. The near-infrared image pixel and the visible light image pixel are made to correspond by using the parallel movement amount and the rotation angle at this time. Accordingly, normalization correction is performed on the pixel intensity of the near-infrared image by performing a process of 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 intensity of the pixel in the portion where the vein is reflected and the portion where the vein is not reflected. First, since the near-infrared light that is scattered and transmitted through the finger 11 is absorbed by the venous blood vessels in the vicinity of the finger surface, the brightness of the pixels in the vein portion becomes dark. The signal strength is 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 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 become as small as the intensity of the transmitted light. Therefore, the value after normalization correction obtained by dividing the transmitted light intensity signal by the reflected light intensity signal is a small value.

  In the part where the vein is not reflected, a part common to the near-infrared image and the visible light image, such as finger dirt and wrinkles, is reflected. When there is no dirt, neither transmitted light nor reflected light is absorbed, so both have the same brightness. Further, when there is dirt, the intensity of both transmitted light and reflected light is attenuated by absorption by the dirt. For this reason, the brightness of the pixels where the vein is not reflected does not become extremely dark only in either the near-infrared image or the visible light image. As a result, the pixel signal intensity after the normalization correction of the portion where the vein is not reflected is almost the same value whether or not there is a stain.

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

  FIG. 3 is a diagram showing a venous blood vessel pattern of a finger. In FIG. 3, reference numeral 31 denotes a contour line of the finger obtained by the differentiation process of the finger image. 32 and 33 are lines representing veins. 34 represents the center line of the outline of the finger. An intersection point between the finger center line 34 and the tip of the finger outline 31 is defined as P point. Let y be the distance between the point X at the distance x from the point P of the finger tip toward the palm and the intersection of the line drawn from the point X in the 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 digitized as a curve Y (x) with x as a variable. This curve Y (x) is used as a vein feature amount. The feature amount of the vein line on one side with respect to the center line 34 is Y1 (x), and the feature amount of the vein line on the opposite side is Y2 (x).

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

  Next, an instruction to input whether to execute the registration process or access is given to the access applicant, and the input is awaited. If the input from the person who wants to access is registration, the information of the personal feature pattern detection device is stored in the database 18-3. In the case of access, the blood vessel video feature information stored in the memory device 18-2 and the blood vessel video feature information corresponding to the initially input ID number and password are extracted from the database 18-3 and collated with each other. .

  As a result of the collation, 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 external 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 a personal identification device using a personal feature pattern detection device according to the present invention.
In this embodiment, an image guide 21-1 is further incorporated into the apparatus shown in FIG. In FIG. 1, the optical system configuration is such that reflected light or transmitted light from the finger is directly incident on the dichroic mirror 13-1, but in the present embodiment, visible light or near infrared light from the finger 11 is used. It is configured to enter the dichroic mirror 13-2 through the image guide 21-1.

   More specifically, the light incident on the lens 22-1 from the finger 11 is imaged on the end surface of the image guide 21-1 by the lens 22-1. The image guide 21-1 transmits the formed 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 near infrared light image and visible light image of the finger are converted into electrical signals by the lens 15 and the CCD element 16-1. Configurations and operations other than this part are the same as those in the first embodiment. In the case of FIG. 1, light from the finger must be directly incident on the dichroic mirror 13-1. For this reason, 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 at a position and a direction in which light from the finger 11 can directly enter the dichroic mirror 13-1. It was. However, in this embodiment, since the image guide 21-1 is made of an optical fiber and has flexibility, the position and direction of the lens 22-1 may be fixed so that light from a finger enters, and the reflecting mirror 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 direction with respect to the finger. Therefore, the degree of freedom increases in the device configuration, and the entire device can be configured compactly.

<Embodiment 3>
FIG. 5 is a block diagram showing a third embodiment of a personal identification device using a personal feature pattern detection device according to the present invention. In this 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 onto the surface of the finger 11 is distributed over the entire surface of the finger by the near infrared light transmitted through the finger 11. Therefore, there is a restriction that only a part of the blood vessel pattern of the finger 11 can be used when observed from one direction as shown in FIG. Therefore, in this embodiment, two image guides 21-2 and 21-3 are used so that the finger 11 can be measured from two directions, and a blood vessel pattern on the finger surface over a wider range can be imaged. Is. Actually, light source LEDs 12-4 and 12-2 and 12-3 and 12-5 are provided on both sides of the image guides 21-2 and 21-3 so that the brightness of the image measured by each optical fiber is uniform. It is arranged.
The operation of this embodiment is the same as that of the first embodiment. In the present 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 a personal identification device using a personal feature pattern detection device according to the present invention. In the present embodiment, the optical means is simplified by removing the dichroic mirror and the reflecting mirror disposed on the input side of the lens 15 from the apparatus configuration of the first embodiment. In other words, in the present embodiment, a necessary image can be captured without using a dichroic mirror by shifting the time of capturing a near-infrared light image and capturing a finger image using visible light. That is, first, the near-infrared light source 12-3 is turned on to photograph a finger image by the near-infrared light, and then the near-infrared light source 12-3 is turned off, and the visible light sources 12-1, 12- are changed. 2 is turned on and a finger image is captured by visible light. Image processing for obtaining a blood vessel image is performed using the near-infrared light image and the visible light image thus captured. Other configurations and operations thereafter are the same as those in the first embodiment. The shooting order of the visible light image and the near-infrared light image may be reversed. Shooting time switching control may be performed manually or may be controlled automatically by the control device 17.

The block block diagram which shows one Embodiment of the personal identification device using the personal characteristic pattern detection apparatus by this invention Operation flow diagram of the apparatus of FIG. Illustration of finger blood vessel pattern The block block diagram which shows 2nd Embodiment of the personal identification device using the personal characteristic pattern detection apparatus by this invention. The block block diagram which shows 3rd Embodiment of the personal identification device using the personal characteristic pattern detection apparatus by this invention. The block block diagram which shows 3rd Embodiment of the personal identification device using the personal characteristic pattern detection apparatus by this invention.

Explanation of symbols

11 ... finger, 12-1 ... near-infrared light LED, 12-2 to 3 ... visible light LED,
13-1 to 4 ... Dichroic mirror, 14-1 to 4 ... Reflector,
15 ... Lens, 16-1 ... CCD imaging device, 16-2 ... Monitor,
17 ... Control unit, 17-1 arithmetic unit, 18-1 ... Data input device,
18-2 ... Memory, 18-3 ... Database,
19-1 to 2 ... interface, 21-1 to 4 ... image guide,
22-1-4 ... lens, 23-1-4 ... lens.

Claims (3)

A light source for irradiating light toward the finger, a picture by the irradiated light and a plurality of imaging means for imaging a plurality of directions with respect to the finger position, during personal identification, from a plurality of directions by the plurality of image pickup means A feature pattern detection apparatus comprising feature pattern detection means for detecting a feature pattern of a finger using an image of a blood vessel pattern of each finger taken. The feature pattern detection apparatus according to claim 1,
The feature pattern detection apparatus, wherein the light source is a light source that emits light from a plurality of directions toward the finger. The feature pattern detection apparatus according to claim 1 or 2,
The light source irradiates near-infrared light or visible light.

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