JPH021242A - Contact type fingerprint detector - Google Patents

Abstract

PURPOSE:To rationalize a finger placing state by a method wherein a guide for positioning a finger is arranged on a light guide member and light emitting elements are arranged to one of the parts opposed mutually through the finger of the guide while photodetectors are arranged to the other part to detect the finger placing state to the light guide member on the basis of the blocking state of the lights emitted from the light emitting elements to the photodetectors. CONSTITUTION:When a finger 18 is placed on the light guide plate 10 inside a guide 12, the lights emitted from light emitting diodes 14a-14d pass through the finger 28 to invade in the light guide plate 10 at the close contact part of the finger 18 with the light guide plate 10 and a part thereof repeats total reflection to reach the under surface of the other end of the light guide plate 10. The detection signals from the photodetectors 16a-16f are supplied to a microcomputer 24. When the lights from the light emitting diodes 14a-14c are blocked by the finger 18 not to reach the photodetectors 16a-16f, the output of the photodetector concerned is turned OFF. The microcomputer 24 investigates which is turned off among the photodetectors 16a-16f to detect the placing state of the finger 18 to the light guide plate 10 and displays guidance on a display device 26 so as to make the finger placing state proper.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Application Fields Prior Art (Figure 6) Problems to be Solved by the Invention Examples of Means and Effects for Solving the Problems - Examples (1st to 5th Examples) Figure) Effects of the extended invention ILE key 1 Regarding a contact-type fingerprint detection device that optically converts the contact state of a finger to the light guide member into a fingerprint image, aim to optimize the state of placing the finger on the light guide member. [1] A guide for positioning the finger is disposed on the light guiding member, a light emitting element is disposed on one side of the guide facing the finger, and a light receiving element is disposed on the other side. The device is configured to detect the state of placement of a finger on the light guide member based on the state of blocking light emitted from the light emitting element-f to the light receiving element.

[Industrial Field of Application] The present invention relates to a contact type fingerprint detection device that optically converts the contact state of a finger to a light guide member into a fingerprint image.

[Background Art] In recent years, as computers have been introduced into a wide range of social systems, system security has become a focus of interest among those concerned. Many questions have been raised about the security of RD cards and passwords, which have been used up until now as a means of verifying identity when entering a computer room or using a terminal. Fingerprints, on the other hand, are considered the most effective means of identifying individuals because they are unique and unchanging throughout life, and much research and development has been conducted on simple personal identification systems using fingerprints. There is.

In a contact fingerprint detection device, a light guide member (e.g. glass plate)
fII means that when you press your finger on the interface between the two, the reflectance and transmittance of light will become uneven depending on the contact state, and the light from the light source will be directed to this interface towards the light guide plate side or Light that enters from the finger side, is reflected by the boundary, or is transmitted through the boundary and is totally reflected within the light guide plate is guided to the image sensor to detect the fingerprint image.

Here, in order to reliably register and verify fingerprint images, it is necessary to obtain fingerprint images over a wide area.

i) Problems to be Solved by the Invention] However, the way the fingers are placed on the light guide plate differs from person to person, and even from time to time even for the same person. In particular, as shown in FIG. 6, when you put your finger on the light guide plate 10'', you can only get a fingerprint image of the toe of the finger, and it is not possible to accurately match it with the registered fingerprint image. There was a case.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a contact-type fingerprint detection device that can optimize the placement of a finger on a light guide member.

[Means for Solving the Problems 1] In order to achieve this object, the present invention provides a contact-type fingerprint detection device that optically converts the state of contact of a finger to a light guide member into a fingerprint image. A guide is disposed on the light guide member, a light emitting element is disposed on one side of the guide facing the finger, a light receiving element is disposed on the other side, and a light emitting element is disposed on the light receiving element. The state in which the finger is placed on the light guide member is detected based on the state in which the light emitted to the light guide member is blocked.

Effect] When you place your finger on the light guide plate between the light emitting element and the light receiving element,
The placement state of the finger on the light guide member is detected based on the light blocking state of the finger.

If this placement is inappropriate, for example, if only the toes of the fingers are in contact with the light guide plate as shown in FIG. 5(B), an instruction is given to press the pads of the fingers against the light guide plate.

Therefore, the state in which the finger is placed on the light guide member can be optimized.

“Example of modification” (1) One example An embodiment of the present invention will be described based on the drawings.

FIG. 1 shows the main structure of a contact type fingerprint detection device.

A U-shaped guide 12 for guiding and positioning a finger is bonded to the upper surface of one end of the light guide plate 10.

On one of the opposing sides of the guide 12, light emitting diodes +4a to +14d are arranged at regular intervals along the length of the guide 12. On the other side of the guide 12,
The light receiving element F' l 6 a~ in the direction perpendicular to the light guide plate IO
A photodiode array 16 in which 16f of photodiodes are arranged is provided.

In order to reduce the influence of ambient light, the light emitting diode 14a
The emission wavelength of ~+4d is preferably in the near-infrared region. Furthermore, on the light receiving surface of the photodiode array I6, there is a light emitting diode 1.
It is preferable to provide a bandpass filter that transmits only light near the wavelength of the maximum emission intensity of 4a to 14d.

If you place your finger on the light guide plate 10 inside this guide 12 for one night, a light emitting diode will appear as shown in Figure 2! 4a-14
The light emitted from the light guide plate 10 passes through the finger 18, and the light enters the light guide plate 10 at the part where the finger 18 is in close contact with the light guide plate 10. A part of the light is repeatedly totally reflected and reaches the other end of the light guide plate 10. Reach the bottom surface.

A phase type and transmission type hologram 20 is adhered to the lower surface, and a two-dimensional image sensor 22 is further disposed below the hologram 20.

[11j] The light beam is diffracted downward by the hologram 20, guided to the outside, and imaged on the imaging surface of the image sensor 22.

As shown in FIG. 3, light receiving element + 6 a = I 6
The detection signal from f is supplied to the microcomputer 24. If the light from the light emitting diodes +4a to +4c is blocked by the finger and does not reach the light receiving element I6, the output of the corresponding light receiving element is turned off. The microcomputer 24 detects the placement state of the finger 18 on the light guide plate 10 by checking which of the light receiving elements +6a to 16f is off, and controls the display 2 so that this placement state is appropriate.
6. Display guidance.

Next, the processing procedure in the microcomputer 24 will be explained based on FIG.

(50,52) Photodetector! When all of 68 to 16f are on, the Zunawara finger 18 is the light guide plate IO"-
If the finger is not placed on the finger, the display 26 displays "Please press your finger on it."

When the finger I8 is placed on the light guide plate 10, the light receiving elements 16a~
At least one of 16f is turned off.

(54) If the lowest light receiving element 16f is turned on, that is, if only the toe of the finger is in contact with the light guide plate 10 as shown in FIG. 5(B), (56) Display 2
6 displays "Please press the pad of your finger."

When the light receiving element 16f is turned off, that is, Fig. 5 (Δ)
As shown, the pad of your finger is a light guide plate! 0 and is in contact with the light guide plate IO, (58) reads the fingerprint image from the image sensor 22 at an appropriate time and compares it with the already registered fingerprint image.

In this embodiment, in particular, the light source for detecting a fingerprint image and the light emitting element for detecting the placement state are shared, so the configuration is simple.

(2) Expansion Note that the present invention includes various other modifications.

For example, not only the light emitting element but also the light receiving element may be arranged on a straight line parallel to the surface of the light guide plate IO to detect whether the position of the tip of the finger is appropriate.

In this case, it is preferable that the light receiving element be disposed close to the light guide plate 10.

Effect of the Invention 1 In the contact type fingerprint detection device according to the present invention, a guide for positioning a finger is disposed on the light guide member, and a light emitting element is provided at one of the positions of the guide facing the finger. A light-receiving element is arranged on the other side, and the state in which the finger is placed on the light guide member is detected based on the blocking state of the light emitted from the light-emitting element to the light-receiving element. If the light guide member is inappropriate, an instruction can be given to place the finger appropriately, and this has the advantageous effect of optimizing the state in which the finger is placed on the light guide member.

[Brief explanation of the drawing]

1 to 5 relate to one embodiment of the present invention, in which FIG. 1 is a partial perspective view without showing the arrangement of the finger Ili device state detection unit, and FIG. 2 shows the optical system of the contact type fingerprint detection device. 3 is a hardware configuration diagram of the finger device state detection section, FIG. 4 is a diagram showing the software configuration of the microcomputer 24, and FIGS. FIG. 3 is an explanatory diagram of the relationship with detection. FIG. 6 is a diagram for explaining the conventional problems. In the figure, IO: light guide plate 12, guide 14: light emitting diode l6: photodiode array i8: finger 20: hologram: image sensor 24: microcomputer 26: display 167 Otodiode array (Figure) Software configuration of microcomputer 24 Figure 4

Claims (1)

[Claims] In a contact type fingerprint detection device that optically converts the contact state of a finger to a light guide member (10) into a fingerprint image, a guide (12) for positioning the finger is connected to the light guide member (10). ), a light emitting element (14a to 14c) is disposed on one side of the guide (12) facing each other with the finger interposed therebetween, and a light receiving element (16a to 16f) is disposed on the other side, From the light emitting elements (14a to 14c) to the light receiving element (16a
A contact-type fingerprint detection device characterized in that a state in which a finger is placed on the light guide member (10) is detected based on a state in which light emitted to the light guide member (10) is blocked.