JPS63205777A - Rugged information detector - Google Patents

Abstract

PURPOSE:To attain uniform illumination and to obtain a clear image by extracting light with single wavelength from light radiated from a light emitting diode used as a light source by a hologram. CONSTITUTION:When the light emitting diode 23 is turned on by touching a contact part 28 with a finger 7, linear illumination light 34 with the single waveform discriminated from the light 33 radiated from each light emitting diode 23 through the hologram 29 linearly illuminate the contact part 28. The dispersed light 35 of the illumination light 34 which is reflected by the projected part of the finger 7 is projected from the hologram 30 downward and made incident upon an image pickup element 25. When a moving board 31 is moved from the left to the right, the illumination light 34 scans the contact part 28 from the left to the right and the dispersed light 35 is moved on the hologram 30 from the left to the right. When the moving board 32 is moved to an image pickup position synchronously with the movement of the dispersed light 35, the fingerprint image of the finger 7 can be photographic. Thus,the light emitting diode 23 more inexpensive than a semiconductor laser can be used and a clear image can be obtained by forming uniform illumination light from the light emitting diode 23 through the hologram 29.

Description

[Detailed Description of the Invention] [Summary] In an unevenness information detection device for detecting fingerprints, etc. of a finger pressed against an uneven surface contact portion of a transparent flat plate, a light emitting diode is used as a light source, and light emitted from the light emitting diode is used. The hologram extracts light of a single wavelength and achieves more uniform illumination than conventional devices using semiconductor lasers, making it possible to capture clearer images.

[Industrial application field]

The present invention relates to an unevenness information detector, and particularly to a fingerprint detection device for detecting fingerprints.

As the information society progresses, stakeholders are becoming increasingly concerned about how to maintain the airtightness of information processing systems, for example, how to ensure system security as computers are introduced into a wide range of social systems. ing.

Therefore, as a means of verifying the identity of a person when entering a computer room or using a terminal, a fingerprint detection device that directly optically detects fingerprints, which differ from person to person and is safe from loss or theft, has been developed. Appeared.

[Conventional technology]

FIG. 3 is a schematic side view showing the main parts of a configuration example of a conventional fingerprint detection device (unevenness information detection device).

In FIG. 3, the fingerprint detection device 1 includes a semiconductor laser 3 and an imaging camera (IL image element) 4 provided below the fingerprint sensor 2. In the fingerprint sensor 2, a hologram 6 is provided on the lower surface of a transparent flat plate 5 made of optical glass, and an imaging camera 4 is arranged to face the hologram 6.

In such a device 1, when a finger 7 is pressed into contact with the finger contact part of the fingerprint sensor 2 and the semiconductor laser 3 is energized, the illumination light 8 is transmitted through the transparent flat plate 5 and illuminates the contact part between the transparent flat plate 5 and the finger 7. do.

Then, the illumination light 8 irradiated on the part of the finger 7 opposite to the concave part 7b formed by the fingerprint is transmitted upward to the transparent flat plate 5 and scattered by the concave part 7b, while the illumination light 8 irradiated to the part in contact with the convex part 7a of the fingerprint is 8 is scattered at the contact interface, and a portion 8a thereof propagates through repeated total reflection and is emitted downward from the detection hologram 6.

As a result, the imaging camera 4 captures a fingerprint image in which the convex portions 7a are bright and the concave portions 7b are dark.

[Problem that the invention seeks to solve]

As explained above, the conventional unevenness information detection device uses a semiconductor laser as a light source. However, since the illumination light of a semiconductor laser has a far-field pattern in which the light intensity decreases in the radial direction from the optical axis, in fingerprint images taken with conventional equipment, the periphery is darker than the center, making it difficult to detect uniform patterns. There was a problem.

[Means for solving problems]

According to FIG. 1, the unevenness information detection device of the present invention aimed at eliminating the above-mentioned problems includes a transparent flat plate 27 provided with an uneven surface contact portion 28 that presses the uneven surface for detection, and a light emitting diode 2.
3, a hologram 29 that distinguishes the single-wavelength illumination light 34 that illuminates the contact portion 28 from the transparent flat plate 27 from the emitted light 33 of the light emitting diode 23; and a hologram 29 that images reflected light 35 of the illumination light 34 on the contact portion 28. It is characterized by comprising an image sensor 25 and a means for scanning the contact portion 28 with illumination light 34 of a single wavelength.

[Effect]

FIG. 2 is a diagram for explaining wavelength discrimination of a hologram, in which the emitted light 12 of the light emitting diode 11 is
3 and is diffracted by the diffraction grating 14, the diffracted lights 12a, 12b, and 12c of the emitted light 12 having a wavelength width become the respective wavelengths λ1. λ2. Since the diffraction direction differs depending on λ, a deviation occurs in the position at which the light reaches the upper surface of the transparent flat plate 15.

The present invention makes it possible to take a uniform image by scanning illumination light of a single wavelength obtained by utilizing the wavelength discrimination property of such a hologram.

〔Example〕

EMBODIMENT OF THE INVENTION Below, the uneven|corrugated information detection apparatus (fingerprint detection apparatus) by the Example of this invention is demonstrated using drawing.

FIG. 1 is a perspective view schematically showing main parts of an unevenness information detection device according to an embodiment of the present invention.

In FIG. 1, the unevenness information detection device 21 is a fingerprint sensor 2.
A light source 24 in which a plurality of light emitting diodes 23 are arranged in a line, and an imaging means 26 in which a plurality of image pickup elements 25 are arranged in a line are provided below the light emitting diode 2.

The transparent flat plate 27 of the fingerprint sensor 22 has a finger contact part 28 near the right end of the front part of the top surface, a hologram 29 for illumination light discrimination near the left end of the front part of the bottom surface, and a hologram for extracting reflected light near the right end of the rear part of the bottom surface. 30 is provided.

Hologram 29 with a predetermined pinch in the direction opposite to contact part 28
A light source 24, which includes a plurality of light emitting diodes 23 parallel to the length direction of a large number of diffraction gratings formed in the same direction, is mounted on a movable table 31 that moves in the left-right direction, and a movable table 31 on which a plurality of image pickup devices 25 are mounted. Reference numeral 32 is a commonly used means for moving the movable base 31 in the left and right direction in conjunction with the movable base 31, that is, moving at a predetermined speed. Move 32.

In such a fingerprint detection device 21, when the finger 7 is pressed against the contact portion 28 and the light emitting diode 23 is turned on, a single wavelength linear illumination that is discriminated by the hologram 29 from the radiation light 33 emitted by each light emitting diode 23 is generated. The light 34 illuminates the contact portion 28 in a linear manner. Then, the convex part (7a) of the finger 7
The scattered light 35 of the illumination light 34 reflected by the hologram 30
The light is emitted downward from the source and enters the image sensor 25 .

Therefore, when the moving table 31 is moved from left to right, the illumination light 34 scans the contact portion 28 from left to right, and the scattered light 35 moves the hologram 30 from left to right.
When the movable table 32 is moved to the imaging position in synchronization with the movement of the scattered light 35, a fingerprint image of the finger 7 is photographed.

In the above embodiment, the fingerprint detection device 21 uses a plurality of light emitting diodes 23 to produce the linear illumination light 34;
This has the effect that the fingerprint detection time is shortened compared to carrying out the present invention by scanning the contact portion 28 with.

Furthermore, in the embodiment described above, the fingerprint detection device 21 has a plurality of light emitting diodes 23 and an image sensor 25 linked together, but this makes it possible to obtain a clearer image than when the image sensor 25 is fixed and the present invention is implemented. This is because it is possible to obtain a clear image.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to use a light emitting diode that is cheaper than a semiconductor light emitting diode, and it is possible to obtain clear images by using a hologram to create uniform illumination light from the light emitting diode. It has a positive effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing the main parts of an unevenness information detection device according to an embodiment of the present invention, FIG. 2 is a diagram for explaining wavelength discrimination of a hologram, and FIG. 3 is a conventional unevenness information detection device FIG. 2 is a schematic side view showing a main part of a configuration example. In the figure, 7 is a finger, 21 is a fingerprint detection device (unevenness information detection device), 23 is a light emitting diode, 25 is an image sensor, 27 is a transparent flat plate, 28 is an uneven surface contact part, 29 is a hologram for single wavelength discrimination , 31. 32 is a moving table, 34 is single wavelength illumination light, and 35 is reflected light. Hologram 9J table-#-separate・yoεglare■durari α diagram follow J
The unevenness of the structure, Kiyone's defeat, and the strategy θ structure, showing the key forces at the bottom.
Side view 77

Claims (3)

[Claims] (1) A transparent flat plate (27) provided with an uneven surface contact part (28) that presses the uneven surface for detection, a light emitting diode (23), and illumination of the contact part (28) from inside the transparent flat plate (27). A single wavelength illumination light (34) is transmitted to the light emitting diode (23).
a hologram (29) for discriminating the light emitted from the illumination light (34); ) comprises means for scanning the contact portion (28). (2) The unevenness information detection device according to claim 1, wherein a plurality of the light emitting diodes (23) are provided in the length direction of the diffraction grating of the hologram (29). (3) The scanning in which a plurality of the light emitting diodes (23) are provided in the length direction of the diffraction grating of the hologram (29), and the light emitting diodes (23) move in a direction perpendicular to the length direction of the diffraction grating. and a means for providing a plurality of said image pickup elements (25) corresponding to said plurality of said light emitting diodes (23), said image pickup elements (25) moving in conjunction with the scanning means of said light emitting diodes (23). The unevenness information detection device according to claim 1, characterized in that it comprises: