JP2009223462A - Personal identification device and personal identification method - Google Patents

Abstract

Provided is a highly accurate personal authentication device and authentication method that simultaneously extract information based on electrical characteristics peculiar to a biological finger when capturing a fingerprint pattern as an image by an optical method. .
In a personal authentication apparatus that recognizes a fingerprint pattern by an optical method and identifies an individual, at least a pair of the transparent plate for placing the finger on a portion where the finger comes into contact does not interfere with the recognition of the fingerprint pattern. A personal authentication device, and a personal authentication method using the same, characterized in that a transparent electrode is provided.
[Selection] Figure 1

Description

The present invention relates to a personal authentication device in which an electrical characteristic detection function is added and identification accuracy is improved in a technology for identifying a person by recognizing a fingerprint pattern by an optical technique, and a personal authentication method using the same. is there.

Various systems that use a laser or the like and input a pattern as an image and analyze it have been developed to date instead of the visual method that has been used for fingerprint authentication. Many methods have been proposed for the sensor part to detect fingerprints, combining the difference in scattering angle between peaks and valleys with the total reflection condition, an optical method to capture the fingerprint pattern directly into the image sensor, and the difference in charge distribution on the contact surface. A method for extracting a pattern by using a semiconductor sensor for detecting the above has been put into practical use. In addition, a method of extracting a fingertip or palm vein pattern using near infrared light for personal authentication has been proposed, and commercialization is also progressing (see, for example, Patent Documents 1 to 3). Since the fingerprint pattern is more complicated than the vein pattern, it may be possible to construct a more accurate personal authentication system. However, if the fingerprint is made of a material such as silicon, the same shape as the finger pad is forged. There is a risk of incorrect authentication.
JP-A-5-73666 Japanese Patent Laid-Open No. 8-16752 JP 2003-331268 A

On the other hand, when the laser is irradiated toward the living body, the intensity distribution of the reflected scattered light forms a dynamic laser speckle (random spot pattern) by moving scattering particles such as blood cells, and this pattern is reflected on the image plane. It is known that the blood flow distribution of capillaries in the vicinity of the living body surface can be imaged by detecting with an image sensor, quantifying the temporal change of the pattern in each pixel, and displaying it in a map. And several techniques and apparatuses which measure the blood flow map under the skin and the fundus oculi by using such a phenomenon have been proposed by the present inventors (for example, see Patent Documents 4 to 9).
Japanese Patent Publication No. 5-28133 Japanese Patent Publication No. 5-28134 JP-A-4-242628 JP-A-8-112262 JP 2003-164431 A JP 2003-180641 A

The present inventor has completed the invention of using the blood flow map shown in the above-mentioned document for personal authentication by combining it with a fingerprint pattern, and has already proposed (see Patent Documents 10 and 11).
In these patent documents, when the blood flow of the fingertip is imaged by the laser blood flow imaging method, the blood flow in the valley portion of the fingerprint is faster than the mountain portion, so that the fingerprint pattern appears in the blood flow map. Is used to authenticate that the finger is alive (Patent Document 10). In addition, by using near-infrared laser light, the blood flow distribution inside the finger is detected, and the accuracy of identity authentication and the exclusion of others is increased, or the blood flow at the fingertip fluctuates in synchronization with the heartbeat, There has also been proposed a method for determining whether the finger is a living finger or a simulated finger by analyzing the waveform (Patent Document 11).

However, even with these methods, for example, if a very thin silicon film imitating fingerprint irregularities is attached to the finger surface, the sensor will pick up the blood flow of the finger behind and live There is a problem of judging that it is. Further, in winter when the room temperature is lowered, the fingertip becomes cold, the blood flow on the surface is lowered, and the pulsation component cannot be detected, so that it is judged as a simulated finger. As far as the inventor is aware, no method or apparatus for overcoming these weaknesses has been proposed yet.
International Publication No. 05/122896 Pamphlet International Publication No. 07/097129 Pamphlet

Conventionally, when a fingerprint pattern (image) is captured as an image, a fingertip is placed on the surface of a transparent plate, and the fingerprint pattern is captured by various optical methods. As far as the inventor is aware, no method or apparatus has been proposed so far for measuring the characteristics of an object and additionally using it for authentication. Accordingly, an object of the present invention is to simultaneously extract information based on electrical characteristics peculiar to a living body finger when capturing a fingerprint pattern (image) as an image by an optical method, and to use this for highly accurate personal authentication. An apparatus and an authentication method are to be provided.

According to a first aspect of the present invention, there is provided a personal authentication apparatus for recognizing an individual by recognizing a fingerprint pattern by an optical method, and a fingerprint is placed on a portion of the transparent plate for placing the finger on a portion where the finger contacts. The personal authentication device is characterized in that at least a pair of electrodes that do not interfere with pattern recognition are provided.

The invention described in claim 2 is the personal authentication device according to claim 1, wherein the electrode is a transparent electrode.

The invention described in claim 3 is the personal authentication device according to claim 1, wherein the electrode is a thin electrode wire.

The invention described in claim 4 is characterized in that the pair of electrodes is provided in a portion where the finger of the transparent plate is in contact with a portion which does not interfere with the recognition of the fingerprint pattern. It is an authentication device.

According to a fifth aspect of the present invention, in the personal authentication method for recognizing an individual by recognizing a fingerprint pattern by an optical method, the fingerprint pattern is recognized on a portion of the transparent plate on which the finger is placed in contact. At least a pair of electrodes that do not interfere is provided, and when recognizing a fingerprint pattern, the electrical characteristics of the current flowing between the electrodes through the placed finger are detected, and a standard set by a human finger set in advance This is a personal authentication method characterized by adding a function for discriminating between human fingers and other simulated fingers in comparison with typical characteristic values.

The invention described in claim 6 is the personal authentication method according to claim 5, wherein the electrical characteristic is a resistance value, an impedance, an AC signal, or a combination thereof.

The invention described in claim 7 is the personal authentication method according to claim 5, wherein different voltages are applied between a plurality of pairs of electrodes.

The invention described in claim 8 is the personal authentication method according to claim 7, characterized in that the combination of applied voltages between a plurality of pairs of electrodes is randomly changed over time.

In an authentication device that captures a fingerprint pattern as an image using an optical technique, a simulated finger that imitates the unevenness of a fingerprint with silicon resin, or a thin sheet that is attached to a finger is used as a real finger. There was a fault of misrecognition. According to the present invention, when recognizing a fingerprint, at the same time, by detecting the electrical characteristics of the finger, there is a clear difference between these simulated fingers and a standard human finger, and the two are distinguished. It becomes possible.

The personal authentication device according to the present invention prevents recognition of a fingerprint pattern at a portion where a finger of a transparent plate for placing a finger contacts in a personal authentication device that recognizes a fingerprint pattern by an optical method and identifies the individual. There is provided at least a pair of electrodes without any. A method for authenticating an individual using such an apparatus detects an electrical characteristic of a current flowing between electrodes via a placed finger when recognizing a fingerprint pattern, and uses a preset human finger. Compared with a standard characteristic value, a function for identifying a human finger and other simulated fingers is added.

In the present invention, any known method / means may be used as a method / apparatus for recognizing a fingerprint pattern by an optical technique. For example, by using a laser or the like to input and analyze a fingerprint pattern as an image into a computer, or by using various sensors that detect fingerprints, combining the difference between the scattering angle of peaks and valleys and the total reflection conditions, the fingerprint Optical methods and apparatuses for capturing a pattern directly into an image sensor are known. Further, in addition to a method / device for recognizing a fingerprint pattern by an optical method, a method may be used in combination with a method / device for extracting a fingertip or palm vein pattern using near-infrared light for personal authentication. . Alternatively,
When the blood flow of the fingertip is imaged by the laser blood flow imaging method proposed by the present inventor, the blood flow in the valley portion of the fingerprint is faster than the mountain portion, so that the fingerprint pattern is present in the blood flow map. It may be a personal authentication method / apparatus or the like using the appearance.

In a conventional device for recognizing a fingerprint pattern by an optical method, a finger is placed on a transparent glass or resin plate. In the present invention, the fingerprint pattern is placed on a portion of the transparent plate that comes into contact with the finger. There is provided at least a pair of electrodes that do not hinder recognition. The electrode that does not hinder the recognition of the fingerprint pattern is specifically a transparent electrode made of an ITO (indium tin oxide) thin film or the like. The position where the pair of electrodes is provided on the transparent plate is, for example, as shown in FIG. 1 (the central square portion indicates the fingerprint observation region. The same applies to the following drawings), and the finger is on the transparent plate. Transparent electrodes may be attached to both sides of the portion in contact with the surface, and electrical characteristics such as electrical resistance may be measured via lead wires. As shown in FIG. 2, the transparent electrode (s) may be arranged at the root and the tip of the part in contact with the finger, and as shown in FIG. It may be provided. Alternatively, in the case of a transparent electrode, as shown in FIG. 4, a pair of electrodes can be provided in parallel across the observation visual field at the central portion of the portion where the finger contacts. Furthermore, as shown in FIG. 5, an electrode may be provided in one place in addition to the metal on the outer periphery of the place where the finger is placed. By changing the position of the electrode for each authentication device or for each fixed period, the forgery protection function can be enhanced.

The electrodes that do not hinder the recognition of the fingerprint pattern may be a pair of electrodes made of thin electrode lines. That is, as shown in FIG. 6, a thin electrode wire is run on the part of the transparent plate where the finger is placed, and a part of the wire is made conductive so that the electrical characteristics of the finger in contact with the conductive part are measured. May be.
Even if an opaque electrode line enters a part of the fingerprint image, the fingerprint pattern line can be connected by software.

Further, the electrode that does not hinder the recognition of the fingerprint pattern may be an electrode in which an insulating layer is attached on the electrode and a part thereof is opened to expose the conductive portion. Specifically, for example, as shown in FIG. 7, an insulating layer is attached on a transparent electrode, a part of the insulating layer is opened to expose a conductive part on the surface, and the position is changed for each apparatus. You may strengthen your defense against your fingers. In this case, even if an attempt is made to read the electrical characteristics of the finger into the device by making a hole in a part of the silicon sheet or the like affixed to the finger, the exposed skin part of the finger is removed from the electrode part. Since it cannot be accurately guessed, it is possible to see through impersonation. Further, as shown in FIG. 8, a part of the thin electrode line may be provided on the insulating layer so as to obtain the same effect as in the case of FIG.

In the present invention, when recognizing the fingerprint pattern, the electrical characteristics of the current flowing between the electrodes through the placed finger is detected, and compared with a standard characteristic value by a human finger set in advance. A function that distinguishes human fingers from other simulated fingers is added,
As the electrical characteristics, for example, it is preferable to use a resistance value, an impedance, an AC signal, or a combination thereof. By analyzing the resistance (impedance) of the fingertip and the electric signal waveform to be taken out, the difference between the numerical value and waveform of the simulated finger that is not a living body can be analyzed, and the living body recognition accuracy can be improved.

In the method and apparatus of the present invention, a plurality of electrode pairs can be used as shown in FIGS. 9, 10 and 11. In the figure, 1 is an ammeter, 2 is a power source, 3 is a switching circuit, and 4 is a number of electrodes. In this case, different voltages may be applied between a plurality of pairs of electrodes. At this time, if a method of randomly changing the combination of applied voltages between a plurality of pairs of electrodes with the passage of time is taken, a system that is more difficult to counterfeit can be constructed.

Since the authentication device or the personal authentication method with enhanced functions as in the present invention combines a complex fingerprint pattern and information based on a living body, forgery is difficult. Taking advantage of this advantage, it can be used in various fields such as entrance / exit monitoring of facilities that require advanced security management and immigration control.

The figure which shows the example which provided the transparent electrode in the both sides of the contact part of a finger | toe. The figure which shows the example which provided the transparent electrode in the front-end | tip and root of the contact part of a finger | toe. The figure which shows the example which provided the transparent electrode in two places at the front-end | tip part of the contact part of a finger | toe. The figure which shows the example which provided the transparent electrode across in parallel within the observation visual field of the center part of the contact part of a finger | toe. The figure which shows the example which provided the transparent electrode in the metal of the outer peripheral part of the contact part of a finger, and one other place. The figure which shows the example which has arrange | positioned two thin electrode wires in the contact part of a finger | toe. The figure which shows the example which stuck the insulating layer on the transparent electrode, opened the part, and exposed the conduction | electrical_connection part on the surface. The figure which shows the example which exposed a part of thin electrode line | wire on the insulating layer. The figure which shows the example using several electrode pairs. The figure which shows the other example using a some electrode pair. The figure which shows another example using several electrode pairs.

Explanation of symbols

1 Ammeter 2 Power supply 3 Switching circuit 4 Many electrodes

Claims (8)

In a personal authentication device for recognizing an individual by recognizing a fingerprint pattern by an optical method, at least a pair of electrodes that do not interfere with the recognition of the fingerprint pattern is provided at a portion of the transparent plate on which the finger is placed in contact with the finger A personal authentication device, characterized in that The personal authentication apparatus according to claim 1, wherein the electrode is a transparent electrode. The personal authentication apparatus according to claim 1, wherein the electrode is a thin electrode line. 2. The personal authentication apparatus according to claim 1, wherein the pair of electrodes are provided at a portion where the finger of the transparent plate is in contact with a portion which does not disturb recognition of the fingerprint pattern. In a personal authentication method for recognizing an individual by recognizing a fingerprint pattern by an optical method, at least a pair of electrodes that do not interfere with the recognition of the fingerprint pattern is provided at a portion of the transparent plate on which the finger is placed in contact with the finger When recognizing the fingerprint pattern, the electrical characteristics of the current flowing between the electrodes through the placed finger is detected and compared with a standard characteristic value set by a human finger. A personal authentication method characterized by adding a function for discriminating between a finger and other simulated fingers. 6. The personal authentication method according to claim 5, wherein the electrical characteristic is a resistance value, an impedance, an AC signal, or a combination thereof. 6. The personal authentication method according to claim 5, wherein different voltages are applied between the plurality of pairs of electrodes. The personal authentication method according to claim 7, wherein a combination of applied voltages between a plurality of pairs of electrodes is randomly changed over time.

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