JP2738906B2 - Collation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information processing technique using a spatial Fourier transform in pattern recognition and the like.

[0002]

2. Description of the Related Art Since pattern recognition can be used for personal identification, for example, a collating apparatus which uses a fingerprint pattern as personal information to identify an individual by using the fingerprint pattern has been proposed (Japanese Patent Laid-Open No. Hei 3-204625). ).

Various methods for performing high-speed pattern correlation by optical calculation have been proposed. One of them is a method called joint transform correlation (JTC) (“Fourier in optical information processing”). conversion",
Optics 21,6,392-399). This method uses a Vander-Lugt optical correlator (“Pattern Recognition by Optical Correlation Phase Filter”, Applied Physics 58,6 (1989)) to accurately calculate the hologram dry plate on which the pattern is written. There is an advantage that no alignment is required.

[0004] In the prior art of the collation device using JTC,
An optical pattern recognition device described in Japanese Patent Application Laid-Open No. 3-280179 (first prior art) and a document "Optical Engineer"
ingVol.30, (12), 1991] (FIG. 2).

The first prior art optical pattern recognition apparatus uses an SLM to simultaneously input a plurality of reference patterns and input patterns.
To obtain a correlation signal between patterns at once.

As shown in FIG. 6, a fingerprint matching device according to a second prior art converts a fingerprint pattern captured by a CCD camera 200 and a reference pattern stored in a memory of a personal computer 201 into an electric address type. Spatial light converter (S
LM) 202, the combined Fourier transform image read out from the SLM 202 is once captured by the CCD camera 203, and the converted image is further written into the SLM 202 to obtain a correlation signal between patterns.

[0007]

The optical pattern recognition apparatus of the first prior art outputs a correlation signal between an input pattern and a plurality of reference patterns. there were. Further, in the fingerprint collation device of the second prior art, since the Fourier transform image read out from the SLM 202 is imaged by the CCD camera 203 into pixels, the Fourier transform image is liable to include noise, and the calculation speed is also higher than the frame rate. (30 msec) is a problem.

The present invention aims to solve these problems.

[0009]

In order to solve the above-mentioned problems, a collating apparatus according to the present invention comprises: (a) a registering means in which a pattern of a predetermined portion of the body surface of a person to be collated is registered in advance as a reference pattern; (B) input means for capturing a pattern of a predetermined portion of the body surface of the person to be collated as an input pattern; and (c) one input pattern captured by the input means and one reference pattern read from the registration means. A first spatial light modulator that converts the coherent light image into one coherent light image, and (d) first Fourier transform means that performs a Fourier transform on the coherent light image to obtain a joint Fourier transformed light image.
(E) a second spatial light modulator that converts the joint Fourier transform light image into a second coherent light image, and (f) a second spatial light modulator that performs Fourier transform on the second coherent light image to obtain a correlation signal image.
And (g) a correlation signal image,
Determining means for determining whether the input pattern and the reference pattern are the same pattern, wherein at least the second spatial light modulator is an optically addressed spatial light modulator comprising a photoconductor and liquid crystal It is characterized by.

[0010]

According to the collating apparatus of the present invention, one reference pattern read from the registration means and one input pattern fetched by the input means are converted into the first coherent light by the first spatial light modulator. Converted to light. The converted first coherent light is converted to a joint Fourier transform light image by a first Fourier transform unit, and further converted to a second coherent light image by a second spatial light modulator. The converted second coherent light image is converted into a correlation signal image by the second Fourier transform means, and the correlation signal image is input to the determination means, and whether the input pattern and the reference pattern are the same pattern Is determined.

Here, since at least the second spatial light modulator is an optical address type spatial light modulator comprising a photoconductor and a liquid crystal, the joint Fourier transform optical image converted by the first Fourier transform means is provided. Is directly provided to the second spatial light modulator.

As described above, according to the present invention, it is not necessary to temporarily convert the joint Fourier-transformed optical image into an electric signal. Therefore, the Fourier-transformed optical image is converted into an electric signal by the above-described second prior art. There is no problem that noise is introduced into the frame and the calculation speed is limited by the frame rate (30 msec).

[0013]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram illustrating the configuration of the matching device according to the present embodiment. As shown in the figure, the matching device of the present embodiment includes an input unit 10 for inputting an input pattern, a memory 20 (registering unit) in which a reference pattern is registered, a CRT 30 for displaying the input pattern and the reference pattern, A control unit 40 that supplies the CRT 30 with the reference pattern. Also, an SLM 50 (first spatial light modulator) that converts the input pattern and the reference pattern into a coherent light image, and a Fourier transform lens 60 that performs a Fourier transform on the coherent light image to obtain a joint Fourier transformed light image
(First Fourier transform means), and an optically addressable SLM 70 (second spatial light modulator) for temporarily converting the joint Fourier transform light image into an intensity image and converting the image into a coherent light image. Furthermore, a Fourier transform lens 80 (second
, A photodetector (PD) 90 that detects a correlation signal image, and a determination unit 100 that determines whether the input pattern and the reference pattern are the same pattern based on the input correlation signal image. .

The input unit 10 includes a prism 11, a light emitting diode (LED) 12 for irradiating the prism 11 with light,
The CCD camera 13 includes a CCD camera 13 for capturing an input pattern, and a lens 14 for imaging the input pattern on the CCD camera 13. The control unit 40 also controls a keyboard 41 for giving an instruction for selecting a reference pattern registered in the memory 20.
Is provided. Further, the read laser beam 11
SLM with half mirrors 111 and 112 for giving 0
Half mirror 11 for providing readout laser beam 110 to SLM 70 between 50 and Fourier transform lens 60
3, 114 are provided between the SLM 70 and the Fourier transform lens 80, respectively.

FIG. 2 is a sectional view showing the structure of the SLM 70. As shown in the figure, the SLM 70 has a sandwich structure in which an amorphous silicon (a-Si) layer 73, a dielectric mirror 74, and a liquid crystal layer 75 are sandwiched between two glass substrates 72 each having a transparent electrode 71 formed on the inner surface. Have. Then, the writing light 76 is applied to the liquid crystal layer 75 on the a-Si layer 73 side.
The reading light 77 is incident on the sides. In a state where the writing light 76 is not applied, the impedance of the a-Si layer 73 is very high, and even if a voltage is applied between the transparent electrodes 71, the voltage applied to the liquid crystal layer 75 is small. When the writing light 76 is applied, the impedance of the a-Si layer 73 decreases, the voltage applied to the liquid crystal layer 75 increases according to the writing light 76, and the liquid crystal molecules move. Here, by irradiating the reading light 77 to the liquid crystal layer 75 side, the reading light 77 is modulated, and a coherent light image is obtained. Note that SLM5
0 preferably has an optically-addressable SLM structure like the SLM 70, but may have an electrically-addressable SLM structure.

Next, the operation of this embodiment will be described.
In the present embodiment, personal identification is performed using a fingerprint of a finger as a pattern of a predetermined portion of the body surface. The fingerprint pattern is input using a total reflection input method.
Is applied to the prism 11, and the fingerprint pattern is obtained from the difference in the reflection conditions when the verification target person presses his / her finger against the prism 11. This fingerprint pattern is
An image is formed on the CCD camera 13 by the CCD camera 13, and the CCD camera 13 converts the image signal into a video signal and sends it to the processing device 40. Further, by operating the keyboard 41 and inputting, for example, a password, the person to be verified selects a fingerprint pattern (reference pattern) registered in the memory 20 in advance, and sends this reference pattern to the control unit 40. . In addition to selecting the reference pattern using the keyboard 41, an ID card may be inserted into a card reader (not shown).

The control unit 40 gives the pair of input patterns and the reference pattern sent to the CRT 30, and
As shown in FIG. 3A, the images are displayed side by side on the screen of the CRT 30 (the left half of FIG. 3A is an input pattern, and the right half is a reference pattern). The input pattern and the reference pattern displayed on the CRT 30 are written to the SLM 50 arranged to face the CRT 30.

The two patterns written on the SLM 50 are read by the read laser beam 110 and are Fourier transformed by the Fourier transform lens 60. And FIG.
A joint Fourier transform image as shown in FIG.
Formed on the a-Si layer. Further, the SLM 70 is read out by the laser beam 110 and subjected to Fourier transform by the Fourier transform lens 80. In this Fourier transform, FIG.
Correlation signals are obtained on both sides of the zero-order light as shown in FIG. This correlation signal is detected by the PD 90. The strength of this correlation signal corresponds to the correlation between the two patterns. This P
The detection signal from D90 is provided to determination section 100, and it is determined by threshold processing whether the input pattern and the reference pattern are the same. The determination result thus obtained is used, for example, for opening and closing a door and unlocking a computer.

The keyboard 41 may be of any type. For example, a general JIS keyboard may be used, or a simplified keyboard 130 as shown in FIG. 4 may be used. The keyboard 130 operates as follows. For example, "Taro Yamada"
Is input, the key “8”, which is the key corresponding to “ya”, is pressed, and then the key “7”, which is the key corresponding to “ma”, is pressed. In order to input "Yamadarou" in this manner, the keys of "87D491" may be pressed in order.

Further, in the present embodiment, the personal identification is performed using the fingerprint, but the present invention is not limited to the fingerprint, and for example, a palm pattern or a sole pattern may be used.

Further, instead of the CRT 30, other display devices such as a liquid crystal display and a plasma display may be used.

The fingerprint input by the input unit 10 may be holographic as shown in FIG. This sensor has a hologram 1 on a part of a transparent glass flat plate (light guide plate) 150.
51 is formed, and the laser light is emitted from the laser light source 152 on the opposite side of the other end.
Detects a fingerprint pattern.

[0023]

According to the collation apparatus of the present invention, the joint Fourier-transformed light image converted by the first Fourier transform means is directly input to the second spatial light modulator and converted into a second coherent light image. doing. As described above, since it is not necessary to temporarily convert the joint Fourier transform light image into an electric signal, noise is not superimposed on the Fourier transform light image, and the calculation speed is not limited to the frame rate (30 msec).

As described above, according to the present invention, a high-speed and practical collation device with a simple configuration is provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a matching device according to an embodiment.

FIG. 2 is a sectional view showing the structure of the SLM.

FIG. 3 is a diagram showing an input image, a Fourier image, and a correlation signal image.

FIG. 4 is a perspective view showing the appearance of a simplified keyboard.

FIG. 5 is a diagram showing an input unit using holography.

FIG. 6 is a block diagram showing a configuration of a conventional fingerprint matching device.

[Explanation of symbols]

10 input unit, 11 prism, 12 light emitting diode, 13 CCD camera, 14 lens, 20 memory, 30 CRT, 40 control unit, 41, 130 keyboard, 50, 70 SLM, 60, 80: Fourier transform lens, 71: transparent electrode, 72: glass substrate, 73:
Amorphous silicon layer, 74 ... dielectric mirror, 75 ...
Liquid crystal layer, 76: writing light, 77: reading light, 90 ...
Photodetector, 100: judgment unit, 110: laser light, 111 to 113: half mirror, 150: glass plate, 151: hologram, 152: laser light source, 153
... imaging device.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G06F 15/64 HG 15/70 460A (72) Inventor Yuji Kobayashi 1126 Nomachi, Ichinomachi, Hamamatsu City, Shizuoka Prefecture Inside Hamamatsu Photonics Co., Ltd. (72) Inventor Tsutomu Hara 1126-1, Nomachi, Hamamatsu City, Shizuoka Prefecture Inside Hamamatsu Photonics Co., Ltd. (56) References JP-A-5-2635 (JP, A) JP-A-4-171510 (JP, A)

Claims (1)

(57) [Claims] 1. A verification device for verifying the identity of a person using a pattern of a predetermined portion of the body surface, wherein the registration unit pre-registers a pattern of the predetermined portion of the body surface of the verification target person as a reference pattern; An input unit that captures a pattern of a predetermined portion of the body surface of the person to be collated as an input pattern; a first coherent light beam that includes one input pattern captured by the input unit and one reference pattern read from the registration unit. A first spatial light modulator that converts the coherent light image into an image, a first Fourier transform unit that performs a Fourier transform on the coherent light image to obtain a joint Fourier transform light image, and a second coherent light beam that converts the joint Fourier transform light image into a second coherent light. A second spatial light modulator that converts the image into an image, and a second Fourier transform that obtains a correlation signal image by performing a Fourier transform on the second coherent light image. Conversion means, and determination means for receiving the correlation signal image and determining whether the input pattern and the reference pattern are the same pattern, and at least the second spatial light modulator A collation device comprising an optical address type spatial light modulator comprising a conductor and a liquid crystal.