JPH03266186A - Fingerprint collator - Google Patents

Abstract

PURPOSE:To refuse the collation of a fingerprint by a replica by providing a noise superposition part whose oscillation is stopped when the input by the finger of an organism is performed and oscillating when the input by the replica is performed at the electrical system of a fingerprint sensor. CONSTITUTION:The noise superposition part 13 performs oscillation with high frequency ordinarily, and it is comprised so that the oscillation of a circuit can be stopped by the dielectric constant and the equivalent electrostatic capacitance, etc., of the finger when the finger of the organism approaches. As a result, a CCD 12 outputs a fingerprint image without a noise on the finger 14. Contrary to this, when the replica 15 approaches, the noise superposition part 13 continues the oscillation. As a result, the noise is superimposed on the output of the CCD 12, and unsharp fingerprint image is outputted, and noncoincidence is always obtained as the result of pattern matching with a dictionary. Thereby, it is possible to refuse the collation of the fingerprint when the input by the replica is performed.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a fingerprint verification device that verifies a person by comparing a human-generated fingerprint image with a dictionary pattern stored in a dictionary, and aims to reject fingerprint verification using a fingerprint replica. , In a fingerprint matching device that detects a match of fingerprints by inputting a fingerprint image from a fingerprint sensor and comparing it with feature information read out from a feature information storage unit that stores fingerprint feature information, the electrical circuit of the fingerprint sensor is The system is configured with a noise superimposition section that stops the oscillation of the circuit when the finger of the living body approaches, and continues the oscillation of the circuit in other cases.

[Industrial Field of Application] The present invention relates to a fingerprint verification device that compares an input fingerprint image with a dictionary pattern stored in a dictionary to confirm the identity of the person.

In recent years, as computers have been introduced into a wide range of social systems, system security has become a focus of interest among those concerned. Many questions have been raised about the security of ID cards and passwords, which have been used up until now to verify one's identity when entering a computer room or using a terminal. On the other hand, fingerprints have two major characteristics: they are unique for everyone, and they remain unchanged throughout life, so they are considered the most powerful means of identity verification, and much research and development has been conducted on simple personal identification systems using fingerprints. ing.

[Prior Art] FIG. 3 is a conceptual diagram of the configuration of a conventional fingerprint verification device. First, the operation at the time of registration will be explained. A fingerprint pattern is detected by pressing a finger against the fingerprint sensor 1, and converted into digital data by an A/D converter (not shown) within the fingerprint sensor 1. The converted digital chill data (fingerprint data) is subsequently converted into binary data of 0" and "1" by the binary circuit 2, and is stored in the frame memory 3.

After the fingerprint data stored in the frame memory 3 is sequentially read out, it enters a feature information extraction/verification circuit 4, where feature information is extracted. Here, the characteristic information means, for example, Fig. 4 (
Refers to branch points as shown in (a) and end points as shown in (b). Fingerprints can be identified by determining where and how many such branch points and end points are present. The extracted feature information is stored in the personal feature information data file 5. The above operations are repeated for a plurality of individuals, and the individual characteristic information is stored in the personal characteristic information data file 5.

When the registration of the amount of feature information in the personal feature information data file 5 is completed in this way, an operation for comparing the fingerprint of the individual is started. In the case of verification, place your finger (the finger used for registration in advance, for example, your index finger) on the fingerprint sensor 1, then press the numeric keypad (
(not shown) to enter your ID number. As a result, the characteristic information extraction/verification circuit 4 can narrow down the search range by determining the search range of the personal characteristic information data file 5 based on the ID number and reading it out at the time of verification.

A fingerprint pattern is detected in the same manner as at the time of registration, and converted into digital data by an A/D converter (not shown) in the fingerprint sensor 1. The converted digital data is subsequently converted into binary data of "0" and "1" by the binarization circuit 2, and is stored in the frame memory 3.

The feature information extraction/matching circuit 4 reads the fingerprint data for matching stored in the frame memory 3, reads out the feature information for each individual stored in the personal feature information data file 5, and performs both matching (pattern matching). )I do. When the number of matching feature information is equal to or greater than a predetermined number, it is determined that the fingerprints match.

[Problems to be Solved by the Invention] Conventional fingerprint matching devices perform fingerprint matching by pattern matching an input fingerprint image and a dictionary pattern read from a feature information storage unit. Therefore, if a precise replica of a fingerprint is made using, for example, silicone rubber, and this replica is input from a fingerprint sensor, there is a problem in that the fingerprint verification device determines that the fingerprints match. In other words, if fingerprint verification is performed only by matching fingerprint patterns, there is a problem in that precisely created replicas of fingerprints cannot be rejected.

The present invention has been made in view of these problems, and an object of the present invention is to provide a fingerprint verification device that can reject fingerprint verification using a fingerprint replica.

[Means for Solving the Problems] FIG. 1 is a storage block diagram of the present invention. In the figure,
The fingerprint sensor 10 includes a support base 11 and a CCD 12 that converts an input fingerprint image into an electrical signal. Pushing stand 1
As the material 1, a transparent material such as glass is used. 1
Reference numeral 3 denotes a noise superimposition unit in which the circuit oscillates or stops when the finger of the living body approaches, and the circuit oscillates in other cases. As shown in the figure, this noise superimposition unit 13 is provided in the electric circuit system of the fingerprint sensor, and normally oscillates at a high frequency. The circuit is configured to stop oscillation due to equivalent capacitance or the like. In other words, the noise superposition unit 13 has an operating point near the critical point where the oscillation conditions based on Nyquist's theorem or the Bode diagram are satisfied.

[Operation] As shown in FIG. 1(a), when the finger 14 of the living body approaches, the oscillation condition is no longer satisfied, and the noise superimposition unit 3 stops oscillation. As a result, the CCD 12 outputs a noise-free fingerprint image of the finger 14. On the other hand, when the replica 15 approaches as shown in (b), the noise superimposition unit 13 continues to oscillate. As a result, noise is superimposed on the output of the CCD 12, outputting an unclear fingerprint image, and pattern matching with the dictionary always results in mismatch. As a result, fingerprint verification in the case of a replica can be rejected.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention. Components that are the same as those in FIG. 1 are designated by the same reference numerals. In the figure, 10 is the aforementioned fingerprint mounting table 11 and CCD 12.
A fingerprint sensor 13 is a noise superimposition unit that performs high-frequency oscillation near critical conditions, and is a feature of the present invention.

14 is a numeric keypad for inputting an ID number etc. when reading a fingerprint; 15 is a keypad for extracting characteristic information from the fingerprint image read by the fingerprint sensor 10, and comparing the read fingerprint with a dictionary (
This is a feature extraction/matching unit that performs pattern matching.

16 is a feature information storage unit that stores the feature information extracted by the feature extraction/verification unit 15 as a dictionary. The operation of the device configured as described above will be explained as follows.

(When registering in a dictionary) First, place the finger to be registered (for example, the index finger) on the fingerprint sensor 1.
0, the fingerprint sensor 10 reads the fingerprint image of that finger and converts it into an electrical signal.

In the case of a biological finger 14, the noise superimposing unit 13 stops oscillating, so the fingerprint sensor 10 outputs a clear fingerprint image. The output of this fingerprint sensor 10 enters a feature extraction/verification section 15.

Here, when a fingerprint registration command is input from the numeric keypad 14, the feature extraction/verification section 15 starts processing the fingerprint image read from the fingerprint sensor 10. First, the fingerprint image read into the feature extraction/verification section 15 is converted into digital data by an A/D converter (not shown). Next, the fingerprint image converted to digital data is divided into two numbers, “0” and “1”, using a predetermined threshold value.
Converted to value data. The converted binary data is stored in a built-in frame memory (not shown).

Next, the feature extraction/verification unit 15 performs preprocessing on the binarized data read from the frame memory.

Pre-processing refers to noise removal, sweat gland removal, line thinning processing, etc. When such processing is completed, the feature extraction/verification unit 15 extracts feature information from the processed fingerprint image. The extracted feature information is sequentially stored in the feature information storage section 16.

(During verification) During verification, the fingerprint image read by the fingerprint sensor 10 is binarized by the feature extraction/verification section 15. Here, if the finger input to the fingerprint sensor 10 is a biological finger, the noise superimposition unit 13 stops oscillation, so that binarization without noise can be performed. On the other hand, when a replica is input, the noise superimposition unit 13 oscillates and superimposes noise on the fingerprint sensor 10.

As a result, the data binarized by the feature extraction/verification section 15 contains a lot of noise.

Next, the feature extraction/verification section 15 performs pattern matching between the binarized fingerprint image and the feature information read from the information storage section 16 of the feature extraction/verification section 15 .

When performing this pattern matching, if the finger is a biological finger, the image read by the fingerprint sensor 10 does not contain noise, so accurate pattern matching can be performed. Since noise is superimposed on the binary data, the binarized data contains a lot of noise, and pattern matching always results in mismatch. Input by such replicas can be rejected.

[Effects of the Invention] As described above in detail, according to the present invention, the noise superimposition part that stops oscillating when an input is made by a biological finger, and oscillates when an input is made by a replica, is connected to a fingerprint sensor. By providing this in the electrical system of the device, it is possible to reject fingerprint verification using a replica.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a conceptual diagram of the structure of a conventional fingerprint collation device, and Fig. 4 is a block diagram showing the characteristic information of a fingerprint. FIG. In FIG. 1, 10 is a fingerprint sensor, 11 is a support stand, and 12 is a CCD. 13 is a noise superimposition unit, 14 is a biological finger, and 15 is a replica.

Claims (1)

[Scope of Claims] A fingerprint matching device that detects a match between fingerprints by inputting a fingerprint image from a fingerprint sensor and comparing it with feature information read out from a feature information storage unit that stores fingerprint feature information, The electrical circuit system of the fingerprint sensor (10) is provided with a noise superimposing section (13) that stops the oscillation of the circuit when a biological finger approaches, and continues the oscillation of the circuit in other cases. A unique fingerprint verification device.