JP2972468B2 - Fingerprint reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingerprint reading apparatus which is used in an entry / exit management system or the like, and which takes in a fingerprint as data in a system for determining a person using a fingerprint.

[0002]

2. Description of the Related Art Conventionally, as a method for taking in a fingerprint image by using this type of apparatus, a method of pressing a finger against a transparent body such as a prism and taking a fingerprint with a camera has been widely used. In this technique, a fingertip is pressed against the surface of the transparent body, light is incident on the back side of the transparent body, and light reflected on the surface of the transparent body is photographed by a camera. Light is transmitted in a portion where the convex portion of the fingerprint is in close contact with the surface of the transparent body, and the light is reflected without being transmitted because the concave portion of the fingerprint does not contact the surface. For this reason, a fingerprint image in which the convex portion of the fingerprint looks dark and the concave portion looks bright is obtained as an image output of the camera. By comparing this image output with a fingerprint image registered in advance and seeing the coincidence, it is possible to determine that the user is the principal.

However, this method has a problem that a fingerprint attached to the surface of a transparent body is collected and abused. Another problem is that fingerprints cannot be read due to stains on the surface of the transparent body. In particular, when the sweat glands are closed and the finger is dry, the above-mentioned reflection and transmission on the surface of the transparent body are not remarkably performed, and the fingerprint may not be read.
Furthermore, there is a problem that the surface of the transparent body is unsanitary because an unspecified number of human fingers come into contact with the surface.

[0004] In order to solve these problems,
There has been proposed a device in which a light beam is directly scanned on a fingertip and the unevenness of a fingerprint is read by the reflected light. For example, US Pat. No. 4,322,163 and JP-A-63-261485.
Is described in Japanese Patent Application Publication No. In this method, the fingerprint can be read in a so-called non-contact manner, so that the above-described problem in using the transparent body can be solved. However, the scanning of the light beam takes time, and the finger must be fixed so as not to move during the scanning of the light beam. However, at present, no effective structure for fixing the finger for the scanning time has been proposed, and while the finger is fixed, a restriction such as prohibiting the user from moving is imposed, which is not preferable. Absent.

[0005] In view of the above, a method for measuring a three-dimensional shape of fingerprint irregularities, that is, a three-dimensional shape, has been proposed. For example, "Three-dimensional image measurement" (Seiji Iguchi, Kosuke Sato, Shokodo, November 1990) and "Basics of optical applied measurement" (edited by the Technical Committee on Measurement of Optical Industry, Society of Instrument and Control Engineers, Showa 58) (July, July).
As an example of measuring the three-dimensional shape of such a fingerprint unevenness, the position information of each point of the fingerprint is obtained by photographing the fingerprint from a plurality of positions and observing the same point of each of a plurality of obtained stereo images. In other words, a stereo method of measuring distance information from a camera is known. Note that a stereo image is, in a narrow sense, two images obtained by photographing the same subject from two cameras located at different positions, but in a broad sense, photographing from three or more cameras. The plurality of images obtained are also referred to as stereo images.

[0006]

When such a stereo method is applied to the measurement of the three-dimensional shape of the unevenness of a fingerprint, a stereo image effective for the measurement is obtained because the unevenness of the subject is minute. For this purpose, it is necessary to take a picture by bringing the camera close to the fingertip. 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 below the outer dimensions of each camera, which is effective for fine fingerprint irregularities. It is difficult to obtain a stereo image. Also, 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 in close proximity, and as the number of cameras increases, the entire apparatus becomes expensive. 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 large and it takes time to perform the movement. A problem arises that the finger must be fixed in the same manner as described above. SUMMARY OF THE INVENTION An object of the present invention is to provide a fingerprint reading apparatus which solves the problem of the stereo system and enables effective fingerprint reading by the stereo system.

[0007]

Means for Solving the Problems The present invention is read
A wall plate having a window on which a fingerprint finger is placed, and
To detect the state where the finger is located in the window
Through the window with the sensor and the detection output of this sensor
An illuminating means for illuminating a fingerprint, and a detection output of the sensor.
Illuminated through a rotary drive and window
A plurality of image pickup units each including an imaging optical system for picking up a fingerprint and an image pickup element are spaced apart from each other by a required size , and
The rotation drive unit uses the center position of the imaging unit as a rotation axis.
Comprising a camera that is driven to rotate, and an image processing circuit for processing the video signal of the fingerprint captured by the respective imaging portions in at least one or more rotational positions of the camera Te, the picture
The image processing circuit scans video signals obtained from the plurality of imaging units.
The distance information is extracted by the teleo method, and based on this distance information,
And fingerprint pattern data is calculated.

[0008]

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 from which a fingerprint is read,
When judging the person, the finger F is placed on the window 1a provided in the wall plate 1.
Face or point. Also,
A display device 2 made of liquid crystal or the like is provided on the front side of the wall plate 1, that is, on the side facing the person, to display whether the position of the finger is appropriate or other information. I have. On the other hand, a fingerprint reader 10 is provided on the back side of the wall plate 1. The fingerprint reader 10 is provided with one camera 11 that is arranged to face the window 1a of the wall plate 1 on which the finger F faces. This camera 11 has a camera housing 12 having a cylindrical shape.
The rotation shaft 13 projects at the center position, and the rotation shaft 13
The motor 14 is driven to rotate in one direction by a motor 14 as a rotation drive unit connected to the motor. This motor 1
4 is provided with a rotation detector (not shown) for detecting the amount of rotation of the rotating shaft 13, and can output the amount of rotation of the camera housing 12 as a detection signal.

In the camera housing 12, a plurality (two in this case) of image pickup units 20 and 30 are lined with respect to the center line of the camera housing 12, as shown in the sectional structure of FIG. They are installed at required intervals so as to be symmetrical. One imaging unit 20 includes an imaging optical system 21 for optically imaging a fingerprint of the finger F, and an imaging device 22 such as a CCD for converting the formed optical image into an electric signal. Is done.
Similarly, the other imaging unit 3 is also configured by an imaging optical system 31 and an imaging element 32. Then, each of the imaging optical systems 21,
Numeral 31 inclines its optical axis toward the center of the camera housing 12, so that the optical axes of the optical systems 21 and 31 intersect at the position of the window 1a or at a position near the window 1a. . Further, each of the imaging elements 22 and 32 corresponds to each of the imaging optical systems 21 and 31, and the camera housing 12 is supported via the support member 15 so that the light receiving surface is perpendicular to the optical axis.
It is fixedly supported inside. The reason why the supporting member 15 is used is that the processing of the camera housing 12 and the imaging devices 22 and 3 are used.
2 to easily adjust the position of the camera housing 12.
In the case where can be processed with high precision, the support member 15 is unnecessary, and the imaging devices 22 and 32 may be directly fixed and supported on the camera housing 12.

A plurality of annular sliding contact rings 16 are provided on the peripheral surface of the camera housing 12 in an annular shape, and each sliding contact ring 16 is electrically connected to each of the image pickup elements 22 and 32. A plurality of sliding contact pieces 17 are disposed in contact with each other and are arranged opposite to a part of the circumference of the camera housing. As a result, 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 extracted to the outside of the camera housing. An illuminator 3 for illuminating the finger F is arranged inside the wall plate 1 facing the window 1a. A transparent plate, here a glass plate 4, is disposed between the window 1a and the front surface of the camera housing 12, and the finger F is moved between the camera housing 12 and each of the imaging optical systems 21,
The lens or the like that constitutes 31 is not touched.
Further, a sensor 5 is disposed 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 a 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
An extracting unit 41 for extracting distance information by a stereo method based on video signals obtained from the respective image pickup devices 22 and 32, and further calculates fingerprint pattern data by binarizing the distance information. An arithmetic unit 42 and an output unit 43 for outputting the fingerprint pattern data from an 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 to control the rotation information of the camera accompanying the rotation of the motor. Circuit 5
0 is input. Further, the sensor 5
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 reading apparatus having this configuration, the wall plate 1
When the person approaches the sensor 5, the sensor 5 detects this, and outputs a detection signal to the control circuit 50. The control circuit 50 receives this and turns on the illuminator 3, and subsequently illuminates the finger F facing the window 1a. At the same time, the camera 11 has two imaging units 20,
30 are driven to form the imaging optical system 2
An image signal of the fingerprint formed by the imaging device 1 and 31 is taken in 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,
At a predetermined timing, the control circuit 50 outputs a drive signal to the motor 14 to rotate the motor. The camera housing 12 is rotated by the rotation of the motor, and when the camera housing 12 is rotated by a predetermined angle, the camera housing 12 is temporarily stopped, and the two imaging units 20, 3 are stopped in the same manner as described above.
0 is used to image a fingerprint. The video signal obtained by this imaging is input to the image processing circuit 40 following the previous video signal. Further, the rotation amount of the camera housing 12 is detected from a rotation detector attached to the motor 14 and is input 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 processing.

Hereinafter, the camera housing 12 is rotated by a required angle unit, and each time a fingerprint is picked up. 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 further binarizes the distance information by the calculation unit 42. Thus, the fingerprint pattern data can be calculated, and the fingerprint pattern data can be output from the output unit 43. It goes without saying that the fingerprint pattern data obtained in this way is collated with the fingerprint pattern data of the registered person in a fingerprint collation device (not shown) to determine the person. In this case, if sufficient fingerprint pattern data can be obtained to determine the identity of the person by one imaging, the motor 14
Therefore, it is not necessary to rotate the camera 11 to perform image capturing a plurality of times. However, imaging is usually performed a plurality of times in order to increase the reliability of the determination.

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

Here, three or more imaging units may be provided in the camera housing, and image processing may be performed by a stereo method using a video signal obtained from each imaging unit. More detailed fingerprint pattern data can be obtained. In addition, the imaging optical system of each imaging unit has a configuration in which each optical axis is directed parallel to the rotation axis of the camera housing, as long as the imaging optical system can sufficiently enter the field of view even when a finger is imaged in close proximity. It may be. Furthermore, the rotation drive unit transmits the rotational force to the rotation axis of the camera to rotate the camera, but is arranged beside the camera to transmit the rotational force via a belt mechanism or a gear mechanism to rotate the camera. It may be. In addition, if the lighting device is devised to shade the unevenness of the fingerprint or project a random dot pattern on the fingerprint, it becomes easy to extract three-dimensional information from the stereo image. Further, if the position and the moving direction of the finger are supported on the display device, the finger can be set at a correct position, and accurate reading can be performed. Furthermore,
When the fingerprint collation device using the output fingerprint pattern data requires a multi-valued 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. What is necessary is just to output.

[0016]

As described above, according to the present invention, read
When a fingerprint finger is placed on the window, the sensor detects it.
And start lighting the fingerprint, and at the same time
Start the rotation of Mera. And with the camera,
The image units are spaced apart by the required size, and the center position of each imaging unit
The image of the fingerprint is taken while being rotated about the rotation axis,
At least one or more rotation positions for each imaging unit
The image signal of the captured fingerprint is steered by the image processing circuit.
The distance information is extracted by the Leo method, and based on this distance information
The fingerprint pattern data is calculated by using
And automatically read fingerprints.
That the application of the personal identification device can be realized.
Fruit is obtained.

[Brief description of the drawings]

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

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

FIG. 3 is a block diagram of the fingerprint reader of FIG. 1;

[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 (1)

(57) [Claims] 1. A wall plate having a window mounted on a wall surface and on which a fingerprint finger to be read is placed, and whether the finger is mounted on the wall plate and the position of the finger is appropriate.
A display for displaying a whether a sensor the finger disposed along said wall plate to sense the state of being positioned in the window, illuminating means for illuminating the fingerprint through the window by the detection output of the sensor A rotation driving unit that is driven to rotate by a detection output of the sensor; a plurality of imaging units each including an imaging optical system for imaging the fingerprint illuminated through the window and an imaging element, having a required size. spaced arrangement, and the camera that is rotated by the rotary drive unit to the center position of the imaging unit as a rotation axis, from the video signal of the fingerprint captured by the respective imaging portions in at least one or more rotational positions of the camera Stereo method
The distance information is extracted by using the fingerprint
An image processing circuit for calculating pattern data, and drive control of the rotation drive unit based on an output of the sensor
And further controls the image processing circuit and the display.
A fingerprint reader having a control circuit .