JPS6274174A - Uneven surface information detecting device - Google Patents

Abstract

PURPOSE:To prevent a drop of S/N by a simple constitution, by providing a dust-proof cover through an air layer on both the upper and the lower faces or one face of a transparent plate. CONSTITUTION:An uneven surface information detecting device is provided with a transparent plate 10 against which an uneven surface 16 to be detected is pressed, a light source 11 for illuminating this uneven surface 16, an optical element 12 for leading out the light which is repeating a total reflection in the transparent plate 10, to the outside by breaking down its total reflecting condition, and a detector 13 for detecting the light which has been led out to the outside. Dust-proof covers 14, 15 are provided through an air layer on both the upper and the lower faces or one face of the transparent plate 10, and it is prevented that fats and oils, moisture, etc. stick onto the transparent plate 10.

Description

[Detailed Description of the Invention] [Summary] This is an uneven surface information detection device in which deterioration of signal light can be prevented by providing a dustproof cover on both the upper and lower surfaces or either one of the upper and lower surfaces of a transparent flat plate that is a light guide plate. shall be.

[Industrial application field]

The present invention relates to an uneven surface information detection device for detecting fingerprints and the like.

Recently, there has been a lot of interest in the security issues of computer application systems, and the development of personal identification technology using fingerprints and the like is progressing.

[Conventional technology]

Conventionally, immediate input type fingerprint sensors have mainly used prisms, but recently, flat-shaped uneven surface information detection devices that can be made smaller and thinner have been developed. As shown in FIG. 2, this is composed of a transparent flat plate 1, a light #2, an optical element 3 such as a hologram, a detector 4, etc., and its operation is performed from below the transparent flat plate 1. When the pressed finger 5 is illuminated by the light source 2, the light 6 reflected from the four parts of the fingerprint passes through the air layer and therefore does not meet the conditions for total reflection within the transparent flat plate 1, and all of the light 6 is emitted to the outside.

However, among the light diffusely reflected from the convex part of the fingerprint, the light 7 reflected under the total reflection condition repeats total reflection within the transparent flat plate j and propagates to the right, and is completely reflected by the optical element 3 provided at the right end of the transparent flat plate. The reflection conditions are broken and the light is emitted to the outside. Detector 4 detects this light.
Gauke is now able to detect fingerprints instantly. (Refer to Japanese Patent Application No. 60-41437) [Problems to be Solved by the Invention] In the conventional device described in -, as shown in FIG. Then, noise light 9 increases due to these fats, water, etc., and signal light 7 decreases, resulting in a disadvantage that the S/N ratio decreases.

The present invention was devised in view of these points, and an object of the present invention is to provide an uneven surface information detection device that has a simple configuration and prevents a decrease in the S/N ratio.

[Means for solving problems]

Therefore, in the present invention, there is provided a transparent flat plate 10 that presses against the uneven surface 16 to be detected, and a light source I that illuminates the uneven surface 16.
I and the light that is repeatedly totally reflected in the transparent flat plate 10,
That total reflection streak! An optical element f-12 that guides the light to the outside with a J-knee that breaks 1; a detector 13 that detects the sum of the light emitted from the outside; Dust-proof covers 14 and 15 are provided with an air layer 4 on both sides of the transparent flat plate 10 or on either side.
It is characterized by the provision of 7-(.

[For production]

By providing a dustproof cover on the transparent flat plate through an air layer, it is possible to prevent oil, fat, moisture, etc. from adhering to the transparent flat plate, and to prevent deterioration of the S/N ratio. Become.

〔Example〕

FIG. 1 is a small diagram illustrating an embodiment of the present invention.

This example number J, transparent plate 10, light source 11, Hole L1 graphic J
The optical elements 12 and detector 13 such as Dustproof cover 1 is installed on one side (both sides in the figure) through an air layer.
4 and 15. Furthermore, this dust cover 1
4 and 15, it is necessary to exclude the lower surface of the uneven surface pressing portion of the transparent flat plate 10 and the optical element 12 portion. However, if the dustproof cover is made of a transparent material, only the uneven surface pressing portion may be removed.

This embodiment configured in this way has a dustproof cover of 14° and 15°.
This makes it possible to prevent oil, fat, moisture, etc. from adhering to the transparent flat plate 10. Therefore, a decrease in the S/N ratio caused by adhesion of oil, fat, moisture, etc. is prevented.

It should be noted that since the dustproof covers 14 and 15 are provided with an air layer interposed between them and the transparent flat plate 10, they do not affect the total internal reflection conditions before the light propagates inside the transparent flat plate 10.

〔Effect of the invention〕

As described above, according to the present invention, deterioration of the S/N ratio of the uneven surface information detection device can be prevented with an extremely simple configuration, and is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a conventional uneven surface information detecting device, and FIG. 3 is a diagram for explaining the problems of the conventional uneven surface information detecting device. In FIG. 1, 10 is a transparent flat plate, 11 is a light source, 2 is an optical element, 13 is a detector, 14 and 15 are dustproof covers, and 16 is an uneven surface.

Claims (1)

[Claims] 1. A transparent flat plate (1) that presses against the uneven surface (16) to be detected.
0), a light source (11) that illuminates the uneven surface (16),
An optical element (1
2) and a detector (13) that detects the light led to the outside.
An uneven surface information detection device comprising: a dustproof cover (14, 15) provided on either the upper and lower surfaces of the transparent flat plate (10) or either surface with an air layer in between. Detection device.