JPH11306332A - Fingerprint detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fingerprint detector which has a relatively simple constitution and can be miniaturized and doesn't require a high assembling precision and is low-cost and obtains an optical image of fingerprint which is vivid as the whole. SOLUTION: This fingerprint detector consists of a flash light source 1, a prism 2 having a first face 2a on which light flashed from the flash light source is made incident, a second face 2c on which a finger whose fingerprint should be picked up is placed, and a third face 2b from which reflected light is emitted, a pinhole 3 through which light emitted from the third face 2b of the prism 3 is narrowed and passes, and an image sensor 4 which receives light passing the pinhole. It is desirable that an artificial retina chip is used as the image sensor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fingerprint detecting device.

[0002]

2. Description of the Related Art Conventionally, fingerprints have been widely recognized in order to confirm whether or not the user is an individual. In recent years, with the spread of information transmission by personal computers and the like, the security of the individual has been required in order to ensure security. As a part of the confirmation, there is a request to use the recognized fingerprint together with or instead of the password at the time of login. In addition, there is also a demand for using fingerprints for collaborating with a fingerprint when buying and selling goods via the Internet, because the security is further improved than simply transmitting the current card number by encryption.

On the other hand, various proposals have conventionally been made as fingerprint detection devices, and a fingerprint detection device as shown in FIG. 4 is a typical type. In FIG. 4, the fingerprint detecting device 50 is a prism 5 having a cross section of a right
2, a light source 51 disposed so as to face a surface 52a forming a right angle of the prism 52, and a lens 53 disposed so as to face another surface 52b forming a right angle of the prism 52
And an image sensor 54 arranged at a position where an image is formed through the lens 53. As the light source 51, a point light source type or a surface light source type is used (the illustrated one is a surface light source type). As the image sensor 54, a CCD is generally used.

A fingerprint (usually a thumb fingerprint) is detected while a thumb (not shown) is applied to the slope 52c of the prism 52. Light emitted from the light source 51 is applied to the surface of the prism 52. 52a enters the prism 52 from the
The light is reflected by the surface 52b and is emitted from the surface 52b. When the light is reflected by the surface 52c, light is absorbed according to the fingerprint, and the light is emitted from the surface 52b as light (optical image) having fingerprint information. The light passes through the lens 53, enters the image sensor 54 located at the focal position of the lens 53,
4 is taken out as a light image by light / current conversion.

[0005]

Since the conventional fingerprint detecting apparatus has the above-described configuration, it has the following disadvantages. (1) Since a lens is used, an edge around the light image is blurred. To improve the image quality, the lens configuration becomes complicated (a plurality of lenses), and the manufacturing cost increases. (2) Since a lens is used, the volume of the entire device increases, and in particular, the height of the entire device increases due to the height of the lens, and it is difficult to reduce the size. (3) Since it is necessary to accurately position the image sensor at the focal point of the lens, the assembling accuracy must be increased. (4) Since a lens is used, the manufacturing cost increases. (5) Since the CCD image sensor only outputs the incident light image pattern as it is, when performing recognition using the output, the subsequent processing mechanism becomes complicated, and it is difficult to reduce the cost. (6) In the combination of the prism and the lens, the surface on which the thumb is placed does not have a parallel positional relationship with the image sensor, and if a certain point is focused, defocus is likely to occur at a position distant therefrom.

Accordingly, it is an object of the present invention to obtain a clear fingerprint optical image at low cost with a relatively simple configuration, which can be miniaturized, does not require high assembling precision, and is low in cost. The present invention is to provide a fingerprint detection device that can be used.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a flash light source, and a flash light from the flash light source is incident on a first surface and a finger to be fingerprinted is placed. A prism that reflects the reflected light from the second surface and emits the reflected light from the third surface, a pinhole for narrowing and passing the light emitted from the third surface of the prism, and a light that passes through the pinhole. And a fingerprint recognition device having an image sensor for receiving light.

Further, according to the present invention, in the above configuration,
An artificial retinal chip (registered trademark No. 4) is used as the image sensor.
No. 000321).

[0009]

Next, embodiments of the present invention will be described. FIG. 1 is a diagram showing a configuration of a fingerprint detection device according to an embodiment of the present invention. FIG. 2 is a sectional view showing the fingerprint detection device together with a timing device for operating the fingerprint detection device. FIG. 4 is a waveform diagram showing a waveform.

Referring first to FIG. 1, a fingerprint detection device 10 is shown. The fingerprint detection device 10 includes a prism 2 having a right-angled isosceles triangle in cross section, a flash light source 1 disposed slightly below a position facing a surface 2 a forming a right angle of the prism 2, and another surface forming a right angle of the prism 2. It comprises a pinhole (opening) 3 arranged to face 2b and an image sensor 4 arranged at an appropriate position where light passing through the pinhole 3 can be captured. Although a CCD may be used as the image sensor 4, an artificial retinal chip is preferably used. Here, the artificial retina chip is an image sensor having an on-sensor image processing function.

The detection of a fingerprint (usually a thumb fingerprint) is performed with a thumb (not shown) applied to the inclined surface 2c of the prism 2, and the light from the flash light source 1 is flashed. Enters the prism 2 from the surface 2a of the prism 2, reflects on the surface 2c, and exits from the surface 2b. When reflected on the surface 2c, light is absorbed according to the fingerprint, and light having fingerprint information is obtained. The light emitted from the surface 2b as a (light image) passes through the pinhole 3, enters the image sensor 4, and is extracted as a light image by light / current conversion by the image sensor 4. When an artificial retinal chip is used as the image sensor 4, the artificial retinal chip has an arithmetic function between pixels, so that processing such as emphasizing a feature amount of an optical image in the artificial retinal chip can be performed. For this reason, since the amount of subsequent image processing can be reduced, the configuration of the entire apparatus can be simplified, the load on the CPU can be reduced, and high speed and low cost can be achieved.

Referring now to FIG. 2, there is shown a timing device 20 of the present invention. In FIG. 2, FIG.
Components having the same functions as the components used in are denoted by the same reference numerals. The timing device 20 includes a casing 10 having a substantially rectangular parallelepiped shape.
By c, it is divided into two chambers 10a and 10b. An opening 10d is formed in the upper part of the chamber 10a. A flash light source 1 is disposed at an appropriate position below the chamber 10a, and the prism 2 is fixed to the casing 10 such that the inclined surface 2c is located on the surface of the opening 10d of the casing 10. Therefore, light flashed from the flash light source 1 enters the prism 2 from the surface 2a of the prism 2, is reflected by the surface 2c on which the thumb is placed, and is emitted from the surface 2b.

A pinhole 3 is formed in a portion facing the surface 2b of the partition 10c, and an artificial retinal chip 4 is disposed in the chamber 10b so as to receive light passing through the pinhole 3. For this reason, the light emitted from the surface 2b passes through the pinhole 3 and is incident on the artificial retinal chip 4, and the optical image is stored as described above. Since the partition 10c is provided, light from the flash light source 1 is incident on the artificial retinal chip 4 in the chamber 10b only through the prism 2 and the pinhole 3.

A support plate 11 is arranged below the casing 10, and a spring 12 for elastically supporting the casing 10 is arranged on the support plate 11. Further, between the casing 10 and the support plate 11, a switch means 13 such as a mechanical switch or a pressure sensor is provided.
Is arranged. A timing generation circuit 14 is provided in connection with this switching means.

The casing 10 is usually located above the support plate 11 so that the switch means 13 is inactive by the spring 12. When a fingerprint is to be detected, the thumb is pressed against the surface 2 c of the prism 2 and the casing is pressed down against the force of the spring 12.
The spring 12 is set so that the switch means is activated when the pressing force reaches a predetermined pressing force. Here, the predetermined pressing force is such that a fingerprint of the thumb can be obtained as a clear light image. Contours of the constituent linear shapes are not clear, and clear fingerprints cannot be obtained. Conversely, if the pressing force is too large, the linear shapes of the fingerprints are crushed, and clear fingerprints cannot be obtained.

As described above, when a predetermined pressing force is exerted on the casing 10 by the thumb, the switch means 1
3 is activated, and the timing generation circuit 14 operates.

When the timing generation circuit 14 operates, the switch is turned on, and after a lapse of a predetermined period, the flash light source 1 is operated to flash light. The retinal prosthesis chip stores (stores) the light image received by the flash of light in the first mode while the switch is on, and performs a series of read kernel processing (direction line segment detection) in the next mode. Do. Here, the kernel process is a process for directly performing a sum or a difference between pixels of a received light image in a chip, and can easily set a calculation pattern between the pixels in a matrix. With this calculation function, processing such as emphasizing or blurring the edge of an image can be performed. It performs various arithmetic processing.

As described above, a clear fingerprint is detected at an appropriate timing.

[0019]

As described above, according to the present invention,
The following effects can be obtained in the fingerprint detection device. (1) There is no blurring at the edge around the light image which occurs when using a lens. (2) Since the pinhole is used without using a lens, the volume of the entire apparatus can be reduced, and in particular, the height of the entire apparatus can be reduced, and the size can be reduced. (3) Since the entire device can be miniaturized, for example, when the fingerprint detection device is used together with a personal computer, it can be incorporated into, for example, a keyboard of the personal computer. (4) Since no lens is used, there is no need to accurately position the image sensor, and it is not necessary to maintain high assembly accuracy. (5) Since there is no lens, the manufacturing cost can be reduced. (6) Since a flash light source (a light source with a wide bandwidth) is used together with the pinhole, the aperture of the pinhole can be reduced. (7) Since the optical image of the fingerprint is taken in when a predetermined pressing force is obtained, a clear fingerprint can be obtained. (8) Since the retinal prosthesis chip itself has a calculation function between pixels, the configuration of the entire apparatus can be simplified, and the speed and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a fingerprint detection device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the fingerprint detection device together with a timing device for operating the fingerprint detection device.

FIG. 3 is a waveform diagram showing a timing waveform.

FIG. 4 is a diagram illustrating a configuration of a typical fingerprint detection device of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flash light source 2 Prism 3 Pinhole 4 Image sensor 10 Casing 11 Support plate 12 Spring 13 Switching means 14 Timing generation circuit 20 Timing device

Continued on the front page. (72) Inventor Takeshi Miura 4-15-1 Hirota, Hirosaki City, Aomori Prefecture (72) Inventor Tohru Suzuki 2-3-28 Shimotsuruma, Yamato City, Kanagawa Prefecture

Claims (5)

[Claims] 1. A flash light source, and light flashed from the flash light source is incident on a first surface, is reflected on a second surface on which a finger to take a fingerprint is placed, and is emitted from the third surface. A fingerprint detecting device, comprising: a prism that forms a light beam; a pinhole for narrowing and passing light emitted from the third surface of the prism; and an image sensor that receives light that passes through the pinhole. 2. The fingerprint detection device according to claim 1, wherein
The prism has a cross section of an isosceles right triangle, the first surface is one surface forming a right angle, the third surface is another surface forming a right angle, and the second surface is a slope. A fingerprint detection device, characterized in that: 3. The fingerprint detecting device according to claim 1, wherein
A fingerprint detection device, wherein the image sensor has an on-sensor image processing function. 4. The fingerprint detecting device according to claim 3, wherein
The image sensor accumulates the received light image, and then
A fingerprint detection device for performing image processing for enhancing a feature amount of a light image as a fingerprint. 5. The fingerprint detection device according to claim 1, further comprising a timing device,
The timing device includes a casing that houses the flash light source, the prism, the pinhole, the image sensor, and a support plate that supports the casing.
A spring disposed between the casing and the support plate for elastically supporting the casing with respect to the support plate; and pressing the casing toward the support plate against the force of the spring. And a timing generating circuit for generating a timing for operating the flash light source and the image sensor when a predetermined pressing force is reached.