JP2695231B2 - Personal verification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] With respect to a personal collation device, it is an object of the present invention to provide a personal collation device capable of accurately identifying whether or not a body is a living body, appropriately eliminating replicas, and improving the precision of personal collation. Having a living body detection means for identifying whether or not the subject is a living body, after confirming that the subject is a living body by the living body detection means, the fingerprint of the specific individual is input as an image, and the characteristic is obtained from the fingerprint image. In the personal collation device that extracts points and performs registration and collation of the fingerprint of the individual based on the characteristic points, the living body detection means has a central wavelength of at least one of white light and green. An illuminating unit that generates light and irradiates the transparent body with which the subject comes into contact with the light from the inner surface, a light receiving unit that has a central wavelength in green and receives the light from the transparent body, and the subject is When touching a transparent object, the From the level at which the force exceeds the second reference level, which is slightly lower than the output when the subject is not in contact,
When the subject shows a peculiar tendency that it falls below a first reference level lower than the reference level and then rises again to stabilize between the first and second reference levels, the subject is a living body. And an identification unit for identifying that there is an item.

[Industrial applications]

The present invention relates to an individual collation device, and more particularly to an individual collation device that includes a living body detection unit and identifies an individual by a fingerprint.

In recent years, as computers have been introduced into a wide range of social systems, system security has attracted interested parties. ID cards and passwords, which have been used as a means of personal identification when entering a computer room or using a terminal, have raised many questions in terms of security. On the other hand, fingerprints are considered to be the most effective means of personal identification because they have the two major characteristics of "universality" and "lifetime immutability". Is being done.

[Conventional technology]

Generally, in a fingerprint sensor, contrast is obtained by utilizing the difference in reflected light amount due to contact / non-contact between the skin and glass on the input surface. Therefore, when a fingerprint replica made of an elastic material such as silicone rubber (an imitation product made of, for example, plaster or soft rubber) is pressed against the input surface, it is as if the finger of the living body were pressed. There is a problem in that a fingerprint image similar to that obtained by pressing is obtained, and it is an issue to provide a fingerprint sensor with a biometric detection function to ensure security.

As a living body detection method in a fingerprint sensor in which a fingertip is pressed against glass on an input surface to optically capture an image, a method of determining a temporal change in sensor output by software is used.

That is, in this method, when the fingertip is pressed against the input surface as shown in FIG. 7, perspiration from the fingertip improves the optical contact between the skin of the ridge of the finger and the glass, resulting in a sensor output. It detects whether or not it is a living body by increasing it with time. However, with this method, it is necessary to repeat software routines such as image capture, A / D conversion, and comparison with the previous output, and during this time, the CPU cannot enter the matching process. Further, even a non-living body such as silicone rubber has the drawback that similar output fluctuations may occur with changes in the contact area.

Therefore, for example, the one disclosed in Japanese Patent Laid-Open No. 61-221883 has been developed with the intention of solving such a problem. This is a method of capturing the change in color of the finger surface when the finger is pressed from the side. That is, in this method, as shown in FIG. 8, the fact that the spectrum of the light reflectance of the finger surface changes between hyperemia and ischemia is utilized to detect the living body.

[Problems to be solved by the invention]

However, the conventional device described in the above publication is very effective because it uses the spectrum of the light reflectance of the finger surface, but when a replica made of a thin film is sandwiched between the finger and the input surface, There is a problem that it is difficult to judge the detection, the replica cannot be properly excluded, and the accuracy of the individual collation decreases.

Therefore, an object of the present invention is to provide an individual collation device capable of accurately identifying whether or not it is a living body, appropriately eliminating replicas, and improving the accuracy of individual collation.

[Means for solving the problem]

In order to achieve the above object, the personal collation device according to the present invention has a living body detection means for identifying whether or not the subject is a living body, and after confirming that the subject is a living body by the living body detection means, In a personal collation device for inputting a fingerprint of an individual as an image, extracting characteristic points from the fingerprint image, and registering and collating the personal fingerprint based on the characteristic point, the living body detecting means is set to white light or green. Illumination means for generating light having a central wavelength in at least one of them and irradiating the transparent body with which the subject comes into contact with the light from the inner surface,
The light receiving unit that has a central wavelength in green and receives light from the transparent body and the output of the light receiving unit when the subject comes into contact with the transparent body are slightly smaller than the output when the subject is not in contact. The peculiarity of falling from a level above the second lower reference level to below a first reference level lower than the second reference level and then rising again to stabilize between the first and second reference levels. And an identification unit that identifies that the subject is a living body.

[Action]

According to the present invention, the output of the light receiving means exceeds the second reference level due to the ambient light before the real finger comes into contact with the transparent body, but immediately after the contact, the reflectance is low due to the engorgement of the finger with the first reflectance. The output falls within the first and second reference levels because the fingertip becomes ischemic and the reflectance increases when the time decreases below the reference level and further elapses. This is because the reflectance of the finger of the living body is different between hyperemia and ischemia,
This state is detected by the identifying means. On the other hand, in the case of a replica, although it may be lower than the first reference level, there is no change in the reflectance due to pressing, so the subsequent change as described above does not occur.

Therefore, whether or not it is a living body can be accurately identified from the change in the output of the light receiving means, and the replica can be eliminated.

〔Example〕

 Hereinafter, the present invention will be described with reference to the drawings.

1 to 4 are diagrams showing a first embodiment of an individual collation device according to the present invention. FIG. 1 is an overall configuration diagram of an individual collation device called a holographic fingerprint sensor, in which 1 is a light source (for example, laser), 2 is a subject (for example, finger or replica as a living body), Reference numeral 3 is a glass flat plate that also serves as a light guide plate (corresponding to a transparent body), 4 is a lens, 5 is a filter, 6 is a light receiver, and 7 is a living body identification circuit.

A light source (corresponding to illumination means) 1 emits white light or light having a center wavelength of green, and a light receiver (corresponding to light receiving means) 6
Is used that has a center wavelength in green. A biometric identification circuit (corresponding to identification means) 7 identifies whether or not the subject 2 is a living body based on the output from the light receiver 6, and outputs a biometric identification signal to the individual collation circuit 8. Is shown as in FIG. Further, the individual matching circuit 8 is guided through the inside of the glass flat plate 3 when it is identified that the subject 2 is a real finger as a living body based on the output (biological identification signal) of the living body identification circuit 7. The fingerprint of the subject 2 is compared with the fingerprint of a specific individual based on the received light, and the detailed configuration is shown in FIG. The light source 1, the glass plate 3, the lens 4, the filter 5, the light receiver 6 and the living body identification circuit 7 together constitute a living body detecting means 9.

First, the biometric identification circuit 7 will be described. In FIG. 2, the biometric identification circuit 7 is composed of comparison circuits 11 and 12, a one-shot multi circuit 13 and an AND circuit 14. The comparison circuits 11 and 12 respectively compare the comparison reference levels A and B (first and second comparison levels).
Corresponding to the reference level of), and the output of the light receiver 6 (hereinafter,
(Referred to simply as sensor output) with comparison reference levels A and B. The comparison reference levels A and B are determined based on the characteristics when a finger as a living body is brought into contact with the glass flat plate 3. For example, in this embodiment, as shown in FIG. The comparison reference level A is set in the middle of the sensor level, and the comparison reference level B is set in the middle of the sensor level. One shot multi circuit 13
Outputs a "H" level signal to the AND circuit 14 when it is detected by the comparison circuits 11 and 12 that the sensor output changes the level → for the first time and then the level → changes. A signal from the comparison circuit 12 is further input to the AND circuit 14, which is a signal for confirming that the subject 2 is continuously in contact with the glass plate 3.
Therefore, the AND circuit 14 is the one-shot multi circuit 13
And the respective signals from the comparison circuit 12 are taken, the presence or absence of fraud such as separating the subject 2 and replacing it with a replica is identified, and the biometric identification signal is used to identify the biometric identification signal only when the real biometric contact is made. Output to.

Next, the individual collation circuit 8 will be described with reference to FIG. 3, which is a block diagram showing the function of the individual collation circuit 8. In this figure, the individual collation circuit 8 is, for example, a 16-bit personal computer. The image input system 21, the image storage circuit 22, and the binarization circuit 2
3, thinning circuit 24, feature point detection circuit 25, intersection angle / intersection point inspection circuit 26, neighborhood pattern transplantation circuit 27 and operation control circuit 28
Has a function represented by.

The image input system 21 receives the light guided from the flat glass plate 3 by the image pickup device and converts it into image input. The image storage circuit 22 stores an image by A / D converting the image input from the image input system 21, and the stored data is taken out to the outside as necessary and sent to the binarization circuit 23. Then, data is exchanged with the binarization circuit 23. The binarization circuit 23 binarizes the image data, and the thinning circuit 24 thins the ridge line and the valley line based on the binarized digital data. The feature point detection circuit 25 extracts the feature points from the thinned image, the intersection angle, the intersection point inspection circuit 26 is a branch point among the feature points,
Check the intersection and intersection of the lines connecting the end points. The neighborhood pattern transplantation circuit 27 cuts out a binarization pattern near the end point based on the output of the intersection angle / intersection point inspection circuit 26 and transplants it to the vicinity of the bridge / break. When the subject 2 is identified as a living body by the biometric identification signal, the operation control circuit 28 registers the fingerprint of the individual and compares the registration data with the image input data to collate the fingerprint.

The above image processing data is sent from the image storage circuit 22 or the operation control circuit 28 to an external CRT display or the like and monitored. Also, in image processing, for example, using a numeric keypad or a mouse to create a window or feature points,
Processing necessary for searching for a branch point is performed. Furthermore, when the subject 2 is a replica, a predetermined display or the like is performed.

 Next, the operation will be described.

As shown in the reflectance characteristic of FIG. 8, human skin has a pressure dependency that the reflectance greatly changes by the pressure in the visible region of 580 nm or less. In FIG. 1, before the subject 2 (hereinafter, appropriately referred to as a finger), which is a real finger, comes into contact with the glass plate 3 in FIG. It shows a high value like the level in Fig. 4. After that, when the finger is brought into contact with the glass flat plate 3, since the blood is still engorged immediately after the contact, the reflectance at the finger is low, and the sensor output like the level is lowered. Further, when the pressure is increased, the fingertip is in an ischemic state, the reflectance is improved, and the sensor output is increased like a level. As shown in FIG. 8, in the case of a finger of a living body, the reflectance hardly changes with respect to the wavelength of “red”, but with respect to the wavelength of “green”, there is a difference between hyperemia and ischemia. This is because the reflectances differ greatly, and the cause is considered to be the action of hemoglobin in the blood. Therefore, whether or not the body is a living body can be identified by observing the change in the sensor output in the process of being pressed from the time of contact with the finger to the pressing sufficient for image capture.

That is, when the subject 2 is a replica (for example,
In the case of silicon rubber), since there is no change in reflectance due to pressing, there is no change from level to level, only change from level to level. Therefore, the living body and the replica can be accurately discriminated by detecting by the living body discrimination circuit 7 whether or not the sensor output passes through the process of change from level to →. As a result, for example, the first subject 2
As a result, it is possible to effectively eliminate fraud such as using the finger of the living body and immediately releasing the finger to replace it with a replica made of a thin film between the finger and the input surface, thus improving the accuracy of individual verification. it can.

In the above embodiment, the light receiver 6 is arranged below the input surface, and the illumination system (corresponding to the light source 1) receives light from the end face of the obliquely cut glass flat plate 3, but the illumination system does not. Like the light receiver 6, it may be arranged directly below.

Further, it is apparent that the invention can be realized even if the comparison circuit 12 is omitted in the biometric identification circuit 7 by devising the effective time of the biometric identification signal.

Next, FIGS. 5 and 6 show the second part of the personal collation device according to the present invention.
It is a figure which shows an Example, and is an example at the time of applying to what is called a prism type fingerprint sensor. In FIG. 5, the structure of the living body detecting means 30 is particularly shown, and the individual collating circuit 8 is omitted since it is the same as that of the first embodiment. In FIG. 5, 31 is a light source, 32 is a subject, 33 is a prism, 34 is a lens, 35 is a filter, and 36 is a light receiver. The output of the light receiver 36 is sent to the same living body identification circuit 7 as a sensor output. To be
It should be noted that the light taken into the individual collation circuit 8 is also taken from the light receiver 36 side. The light source 31, the prism 36, the lens 34, the filter 35, the light receiver 36 and the living body identification circuit 7 are living body detecting means.
Make up thirty.

In the above configuration, when the subject 2 is a finger, the total reflected light enters the light receiver 36 until the finger comes into contact with the prism 33, so that the sensor output is as shown in FIG. Shows a high level like. When the finger touches, the total reflection condition collapses at the contact portion of the ridge and the prism 33 and scattered light increases, and because the reflectance for `` green '' light in a hyperemic state is low, As indicated by, the output level of the sensor decreases. When the pressure is further increased, the fingertip becomes ischemic and the reflectance improves. The sensor output rises like. The principle of excluding the replica is the same as that of the previous embodiment, and therefore, the same effect can be obtained also in this embodiment.

〔The invention's effect〕

According to the present invention, it is possible to accurately identify whether or not a body is a living body and appropriately exclude a replica, and it is possible to improve the accuracy of individual verification.

[Brief description of the drawings]

1 to 4 are diagrams showing a first embodiment of an individual collation apparatus according to the present invention, FIG. 1 is an overall configuration diagram thereof, FIG. 2 is a block diagram of its biometric identification circuit, and FIG. FIG. 4 is a block diagram of an individual collation circuit, FIG. 4 is a characteristic diagram of its sensor output, FIGS. 5 and 6 are diagrams showing a second embodiment of the individual collation device according to the present invention, and FIG. FIG. 6 is a characteristic diagram of the sensor output thereof, FIG. 7 is a characteristic diagram of the sensor output in the conventional individual collation device, and FIG. 8 is a diagram showing the reflectance characteristic of the finger. 1, 31 ... light source (illuminating means), 2, 32 ... subject, 3 ... glass flat plate (transparent body), 4, 34 ... lens, 5, 35 ... filter, 6, 36 ... light receiver (Light receiving means), 7 ... Biometric identification circuit (identification means), 8 ... Individual verification circuit, 9, 30 ... Biometric detection means, 11, 12 ... Comparison circuit, 13 ... One-shot multi-circuit, 14 ... … And circuit, 33 …… Prism (transparent body).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Ikeda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited

Claims (1)

(57) [Claims] 1. A living body detecting means for identifying whether or not the subject is a living body, and after confirming that the subject is a living body by the living body detecting means, an image of a fingerprint of a specific individual is input, In the personal collation device for extracting the characteristic points from the fingerprint image and registering and collating the fingerprint of the individual based on the characteristic points, the living body detection means is at least one of white light and green. An illuminating unit that emits light having a central wavelength to the inside and irradiates the transparent body with which the subject comes into contact with the light from the inner surface, and a light receiving unit that has a central wavelength in green and receives the light from the transparent body. And an output of the light receiving means when the subject comes into contact with the transparent body, which is slightly lower than the output when the subject does not come into contact with the second body.
Of the peculiar tendency of falling below the first reference level lower than the second reference level and then rising again to stabilize between the first and second reference levels. An individual collation apparatus comprising: an identification unit that identifies that the subject is a living body when shown.