JPH06168319A - Fingerprint reader - Google Patents

Abstract

PURPOSE:To obtain a fingerprint reader capable of rapidly and highly accurately reading out a fingerprint by a stereoscopic system. CONSTITUTION:The fingerprint reader 10 is provided with a camera 11 constituted of arranging plural image pickup parts 20, 30 each of which is constituted of an image forming optical system and an image pickup element, a rotational driving part 14 capable of rotating the camera 11 around a rotational axis, i.e., the center position of each image pickup part, and an image processing part 40 for processing the video signals of a fingerprint respectively picked up by respective image pickup parts at least on one rotational position of the camera 11. Since the video signals of the fingerprint picked up by plural image pickup parts mounted on one camera are processed by the image processing part 40 by means of the stereoscopic system and finger print pattern data are obtained, the size of the device can be made compact and rapid and highly accurate reading of the fingerprint can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingerprint reader for use in a room entrance / exit management system or the like, which is used in a system for determining the identity of a person by fingerprints and taking in the fingerprints as data.

[0002]

2. Description of the Related Art Conventionally, as a method for capturing an image of a fingerprint used in this type of apparatus, a method of pressing a finger against a transparent body such as a prism and photographing the fingerprint with a camera has been widely used. In this method, a fingertip is pressed against the surface of the transparent body, light is incident from the back surface of the transparent body, and the light reflected by the surface of the transparent body is photographed by a camera. Light is transmitted at the portion where the convex portion of the fingerprint is in close contact with the surface of the transparent body, and the concave portion of the fingerprint does not contact the surface, so that light is reflected without being transmitted. Therefore, a fingerprint image in which the convex portions of the fingerprint are dark and the concave portions are bright is obtained as the image output of the camera. By comparing this image output with a fingerprint image registered in advance and observing the coincidence, it is possible to determine the person himself / herself.

However, this method has a problem that fingerprints adhering to the surface of the transparent body are collected and abused. There is also a problem that fingerprints cannot be read due to stains on the surface of the transparent body. In particular, when the sweat glands are occluded and the finger is dry, the above-described reflection and transmission on the surface of the transparent body are not significantly performed, and the fingerprint may not be read.
Furthermore, since the fingers of an unspecified number of people come into contact with the surface of the transparent body, there is a problem that it is unsanitary.

Therefore, in order to solve these problems,
It has been proposed that a fingertip is directly scanned with a light beam and the reflected light is used to read the unevenness of a fingerprint. For example, U.S. Pat. No. 4,322,163 and JP-A-63-261485.
There is one described in the publication. In this method, the fingerprint can be read without contact, so that the problem in using the transparent body can be solved. However, it takes time to scan the light beam, and the finger must be fixed so that the finger does not move during the scanning of the light beam. However, at present, an effective structure for fixing the finger only for the scanning time has not been proposed, and while the finger is fixed, it imposes restrictions such as prohibiting movement on the user, which is not preferable. Absent.

Under these circumstances, a method for measuring the three-dimensional shape of the unevenness of the fingerprint, that is, the three-dimensional shape has been proposed. For example, "Three-dimensional image measurement" (Seiji Iguchi, Kosuke Sato, Shokoido, November 1990) and "Basics of applied optical measurement" (edited by the Optical Industry Measurement Research Special Committee, The Society of Instrument and Control Engineers, 1983) (July, 2013) etc. for detailed explanation.
As an example of measuring such a three-dimensional shape of the unevenness of the fingerprint, the fingerprint is photographed from a plurality of positions, and the same point of each of the obtained stereo images is observed to obtain the position information of each point of the fingerprint. In other words, a stereo method for measuring distance information from a camera is known. A stereo image is, in a narrow sense, two images obtained by shooting the same subject from two cameras at different positions, but in a broad sense, a stereo image is taken from three or more cameras. The plurality of images obtained are also called stereo images.

[0006]

When such a stereo method is applied to the measurement of the three-dimensional shape of the unevenness of the fingerprint, the unevenness as a subject is minute, and therefore a stereo image effective for the measurement is obtained. In order to do this, it is necessary to bring the camera close to the fingertip and take a picture. Moreover, in order to perform highly accurate measurement, it is preferable that the number of stereo images is as large as possible. However, conventionally, since a plurality of independent cameras are arranged close to each other to photograph a finger, the two cannot be brought close to each other within the outer dimension of each camera, which is effective for fine unevenness of fingerprints. It is difficult to obtain a stereo image. Further, in order to obtain a large number of stereo images, a large number of cameras are required, and it is difficult to arrange these cameras close to each other, and the entire apparatus becomes expensive as the number of cameras increases. There is also the problem of becoming.
For this reason, it has been proposed to take a plurality of images while moving one camera, but the moving mechanism becomes larger and it takes time to move, and in the case of the optical scanning method described above, As with the above, the problem that the finger must be fixed occurs. An object of the present invention is to solve the problems of the stereo method and to provide a fingerprint reading device capable of effectively reading a fingerprint by the stereo method.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there are provided a camera in which a plurality of image pickup portions each composed of an image-forming optical system and an image pickup element are arranged with a required size, and the camera is rotated about the center position of each image pickup portion. A rotation drive unit that can rotate as an axis and an image processing circuit that processes a video signal of a fingerprint captured by each imaging unit at at least one rotation position of the camera are provided. In addition, it is preferable that the plurality of imaging units are configured such that their respective optical axes are inclined with respect to the rotation axis of the camera, and the respective optical axes intersect at the fingerprint position or a position in the vicinity thereof. Further, the image processing circuit is configured to extract distance information from the video signals obtained from the plurality of image pickup units by a stereo method and binarize the distance information to calculate fingerprint pattern data.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a main part of the present invention, in which F is a finger for reading a fingerprint,
When judging the person, a finger F is put on the window 1a provided on the wall plate 1.
To face or point to. Also,
A display device 2 made of liquid crystal or the like is provided on the front surface side of the wall plate 1, that is, the side facing the person, so that it is possible to display whether or not the position of the finger is appropriate or other information. There is. On the other hand, a fingerprint reading device 10 is provided on the back side of the wall plate 1. The fingerprint reading device 10 is provided with one camera 11 arranged to face the window 1a of the wall plate 1 on which the finger F faces. This camera 11 has a cylindrical camera housing 12, and this camera housing 12 is
The rotary shaft 13 is projected at the center position of the rotary shaft 13.
The motor 14 is connected to the motor 14 as a rotation driving unit and is driven to rotate in one direction. This motor 1
A rotation detector (not shown) that detects the amount of rotation of the rotating shaft 13 is provided on the unit 4, and the amount of rotation of the camera housing 12 can be output as a detection signal.

As shown in the sectional structure of FIG. 1 in FIG. 2, a plurality of (here, two) image pickup units 20 and 30 are arranged in a line with respect to the center line of the camera casing 12 in the camera casing 12. The interiors are arranged at required intervals so that they are symmetrical. One image pickup unit 20 is composed of an image forming optical system 21 for optically forming a fingerprint of the finger F and an image pickup device 22 such as a CCD for converting the formed optical image into an electric signal. To be done.
Similarly, the other imaging unit 3 also includes an imaging optical system 31 and an imaging element 32. Then, each of the imaging optical systems 21,
The optical axis of 31 is inclined toward the center of the camera housing 12, and the optical axes of the optical systems 21 and 31 are crossed at the position of the window 1a or a position in the vicinity thereof. . Further, the respective image pickup devices 22 and 32 are made to correspond to the respective image forming optical systems 21 and 31, and the camera housing 12 is provided via the support member 15 so that the light receiving surface thereof is perpendicular to the optical axis.
It is fixedly supported inside. The support member 15 is used for processing the camera housing 12 and the image pickup elements 22 and 3.
This is because the position of the camera housing 12 can be easily adjusted.
If it can be processed with high precision, the support member 15 is not necessary, and the image pickup devices 22 and 32 may be directly fixed and supported on the camera housing 12.

A plurality of annular sliding contact rings 16 are arranged in an annular shape on the peripheral surface of the camera housing 12, and each sliding contact ring 16 is electrically connected to each of the image pickup devices 22 and 32. They are connected to each other, and a plurality of sliding contact pieces 17 arranged to face a part of the circumference of the camera housing are in contact with each other. Thereby, the sliding contact ring 16 and the sliding contact piece 17
The video signals picked up by the image pickup devices 22 and 32 are taken out through the camera housing. An illuminator 3 for illuminating the finger F is arranged inside the wall plate 1 facing the window 1a. Further, a transparent plate, here a glass plate 4, is arranged between the window 1a and the front surface of the camera housing 12, and the finger F is used for the camera housing 12 and the respective imaging optical systems 21 ,.
It does not touch the lens and the like that form the part 31.
Further, a sensor 5 is arranged near the wall plate 1,
It is configured to detect the approach of a person and output a predetermined signal.

FIG. 3 is a block diagram of the fingerprint reading apparatus according to the present invention. The two image pickup devices 22 and 32 are connected to an image processing circuit 40, respectively. This image processing circuit 40
In addition, based on the video signals obtained from the image pickup devices 22 and 32, an extraction unit 41 that extracts distance information by a stereo method, and further digitizes the distance information to calculate fingerprint pattern data. The calculation unit 42 and the output unit 43 that outputs the fingerprint pattern data from the output terminal are provided. The image processing circuit 40 is controlled by a control circuit 50. The control circuit 50 is connected to the motor 14 to control the rotation of the motor and control the rotation information of the camera accompanying the rotation of the motor. Circuit 5
It is designed to be input to 0. Further, the sensor 5
The detection signal of is input to the control circuit 50. On the other hand, the control circuit 50 outputs a predetermined display signal to the display 2.

According to the fingerprint reader having this structure, the wall plate 1
When a person approaches, the sensor 5 detects this and outputs a detection signal to the control circuit 50. In response to this, the control circuit 50 turns on the illuminator 3, and then illuminates the finger F facing the window 1a. At the same time, the camera 11 has two image pickup units 20,
The image pickup optical system 2 is driven by driving the image pickup devices 22 and 32 of 30.
The image signal of the fingerprint imaged by 1, 31 is captured as an electric signal. This image signal is input to the image processing circuit 40 via the sliding contact ring 16 and the sliding contact piece 17. continue,
The control circuit 50 outputs a drive signal to the motor 14 at a predetermined timing to rotate the motor. The rotation of the motor causes the camera housing 12 to rotate, and when the camera housing 12 is rotated by a predetermined angle, the camera housing 12 is temporarily stopped, and the two image pickup units 20 and 3 are similarly operated as described above.
An image of a fingerprint is taken at 0. The video signal obtained by this imaging is input to the image processing circuit 40 after the previous video signal. Further, the rotation detector attached to the motor 14 detects the rotation amount of the camera housing 12 and inputs it to the control circuit 50. As a result, the control circuit 50 recognizes the rotational position of the turtle housing 12, determines the video signal at the rotational position, and causes the image processing circuit 40 to perform the processing.

Thereafter, the camera housing 12 is rotated by a required angle unit, and the fingerprint image is taken each time. As a result, a large number of video signals are input to the image processing circuit 40, the extraction unit 41 extracts distance information by the stereo method based on these video signals, and the arithmetic unit 42 further binarizes the distance information. Thus, the fingerprint pattern data can be calculated and the fingerprint pattern data can be output from the output unit 43. Needless to say, the fingerprint pattern data obtained in this manner is compared with the fingerprint pattern data of the person who has already been registered in the fingerprint collation device (not shown) to determine the person. In this case, if the fingerprint pattern data sufficient to determine the person is obtained by one image pickup, the motor 14
Therefore, it is not necessary to rotate the camera 11 and perform imaging a plurality of times. However, normally, imaging is performed a plurality of times in order to improve the reliability of the determination.

As described above, in this fingerprint reading device, since the fingerprint is picked up by using the single camera 11 having the plural image pickup units 20 and 30 integrally, a device for picking up the image by using the plural cameras. It is possible to reduce the space as compared with. In particular, in this configuration, since the plurality of image capturing units 20 and 30 can be imaged at different positions by rotating the camera housing 12, the image capturing can be realized without protruding from the space where the camera is installed. In addition, it is possible to take images at multiple times faster than a device that takes multiple times while moving one camera.
It enables quick fingerprint reading. Furthermore, each imaging unit 2
Since the optical axes of the image forming optical systems 21 and 31 of 0 and 30 are directed to the finger F, it is easy to perform close-up imaging of the finger.
It becomes possible to read the fine unevenness of the fingerprint with high accuracy.
The sensor 5 is provided and the apparatus is started only when a person approaches, so that wasteful power consumption can be prevented. Further, by disposing the transparent plate 4 on the front side of the camera, there is no possibility that a finger touches the camera and the finger is injured.

Here, three or more image pickup units may be provided in the camera housing, and image processing may be performed by a stereo method using video signals obtained from the respective image pickup units. It is possible to obtain more detailed fingerprint pattern data than in the case where there is. Further, the image forming optical system of each image pickup unit is configured so that its optical axis is parallel to the rotation axis of the camera housing as long as it can be sufficiently included in the shooting angle of view even when the finger is closely imaged. May be Further, the rotation drive unit transmits the rotational force to the rotation axis of the camera to rotate the camera, but it is arranged beside the camera to transmit the rotational force via the belt mechanism and the gear mechanism to rotate the camera. You may Further, if the lighting device is devised so that the unevenness of the fingerprint is shaded or a random dot pattern is projected on the fingerprint, it becomes easy to extract the three-dimensional information from the stereo image. Further, by supporting the position and movement direction of the finger on the display device, the finger can be set at the correct position, and accurate reading becomes possible. Furthermore,
If the fingerprint matching device using the output fingerprint pattern data requires a multivalued image instead of a binary image, the extracted distance information is output as it is or the distance information is truncated to a predetermined number of bits. It should be output.

[0016]

As described above, according to the present invention, a camera in which a plurality of image pickup units are arranged with a required size and spaced from each other can be rotated by a rotation drive unit, and each image pickup unit can be rotated at at least one rotation position of the camera. An image processing circuit for processing the image signal of the picked-up fingerprint is provided, and the fingerprint pattern data is obtained in the image processing circuit.
You can get video signals of multiple fingerprints with one camera,
The fingerprint method can be detected by the stereo method, and the device can be downsized. In addition, by tilting the plurality of image pickup units so that their optical axes intersect at the fingerprint position or a position in the vicinity thereof, it is possible to perform close-up photography of the fingerprint in each of the image pickup units, and detect fine unevenness of the fingerprint. This enables highly accurate detection. Furthermore,
In the image processing circuit, the distance information is extracted from the video signals obtained from the plurality of image pickup units by the stereo method, and the distance information is binarized to calculate the fingerprint pattern data. It can be used as it is.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a main part of an embodiment of a fingerprint reading device of the present invention.

FIG. 2 is a cross-sectional configuration diagram of FIG.

FIG. 3 is a block diagram of the fingerprint reading device of FIG.

[Explanation of symbols]

 1a window 10 camera 11 camera housing 14 motor 20,30 imaging unit 21,31 imaging optical system 22,32 imaging device 40 image processing circuit 50 control circuit

Claims (3)

[Claims] 1. A camera in which a plurality of image pickup units each composed of an image forming optical system and an image pickup device are arranged with a predetermined size, and a rotary drive capable of rotating the cameras with the center position of each of the image pickup units as a rotation axis. And a image processing circuit for processing a video signal of a fingerprint imaged by each imaging unit at at least one rotation position of the camera. 2. The plurality of image pickup units are configured such that their respective optical axes are tilted with respect to the rotation axis of the camera, and the respective optical axes intersect at a fingerprint position or a position in the vicinity thereof. Fingerprint reader. 3. The fingerprint according to claim 1, wherein the image processing circuit extracts distance information from the video signals obtained from the plurality of image pickup units by a stereo method, and binarizes the distance information to calculate fingerprint pattern data. Reader.