JPS62206688A - Input method for uneven surface information - Google Patents

Abstract

PURPOSE:To prevent a fingerprint images from being used illegally by the 3rd party by being copied by exposing disturbing light even if the 3rd party tries to photograph a monitor image during the input of uneven surface information. CONSTITUTION:When a hologram Hm for monitoring is irradiated with the disturbing light 17 such as infrared light by a light source 16 on the reverse side of the hologram, part of the light is transmitted to above together with information light, so disturbing light is generated by the hologram Hm as well as light of a fingerprint image and reaches the eyes 14 of an input perform and a camera 15. This disturbing light is not visible light, so it is not recognized with the eyes 14 of the input person and only the fingerprint image is seen. The disturbing light incident on the camera 15 as well as the fingerprint image on the hologram Hm for monitoring and exposed, so overexposure is caused and an unsharp fingerprint image due to the disturbing light is photographed.

Description

[Detailed Description of the Invention] [Summary] In a device that can monitor the input state with a monitor hologram when the scattered light from the convex portion pressed against the uneven surface information input section is led out and detected by the hologram, By illuminating the monitor hologram from the back side with interference light of a wavelength different from that of the monitor light source and invisible to the naked eye, it is impossible to photograph the monitor image.

[Industrial application field]

In today's highly information-oriented society, the establishment of security technology in computer systems has become an urgent task. In particular, strict control of entry into the computer room is an important issue in maintaining the confidentiality of information, in order to correctly identify the people handling this system. Currently, for this purpose, passwords and Ill cards are being put into practical use, and hermit verification systems using fingerprints and the like are beginning to be introduced.

Up until now, the methods of inputting information on uneven surfaces such as fingerprints have been to apply ink and press it once on paper and then input it using an image sensor, and to use optical elements such as prisms to input information on the glass/air interface. Another method was to instantly obtain a concavo-convex pattern by making a light beam incident at an angle greater than the critical angle.

The present invention relates to a method for monitoring the input state of uneven surface information in a device such as the latter that instantly detects uneven surface information using an optical element.

[Overview of uneven surface information detection device]

The conventional method of applying ink to a finger, stamping it on paper, and inputting using an imaging system has the problem of staining the finger with ink every time, and also making it difficult to input due to uneven application, blurring, etc. was.

In order to solve this problem, an optical real-time input means using a prism 11 as shown in FIG. 3 has been proposed, as also proposed in Japanese Patent Laid-Open No. 55-81321. This involves pressing the fingerprint (uneven pattern) on the surface of the finger 10 onto the oblique side of the prism 11, and applying illumination light to the oblique side.
2 is incident at a critical angle or more. The incident light is scattered by the raised portions 6 of the fingerprint, is totally reflected at the interface 13 with air in the recessed portions 7, and enters the detector 4 such as an image sensor, so that the uneven pattern can be detected.

However, due to leakage light due to multiple reflections, the recess 7
There was a drawback that scattered light from the wafer reaches the detector 4, reducing the contrast of the concave-convex pattern. Furthermore, since a prism is used, it is not possible to reduce the thickness. Particularly when detecting uneven patterns on the entire surface of an army, the prism must be made larger, resulting in a major loss of equipment.

Therefore, the applicant of the present invention proposed a device as shown in FIG. 4('b) in Japanese Patent Application No. 60-41437. 1 is
It is a flat plate that is transparent to the light of the light source 2 used, and an uneven surface 5 such as a fingerprint is pressed against the uneven surface information input section 1a. A light source 2 for illuminating this uneven surface 5 is arranged directly below. A hologram 3 that takes out the light 9 that is totally reflected in the transparent flat plate 1 to the outside is arranged at a position away from the uneven surface information input section 1a, and a TV camera or the like that detects the light taken out by the hologram 3. A detector 4 is provided.

Fingerprints can also be photographed by placing a film in place of the TV camera.

With the uneven surface 5 such as a fingerprint pressed against the transparent flat plate 1,
When the uneven surface 5 is illuminated by the light source 2, the subsequent paths of light scattered by the convex portions 6 of the uneven surface 5 and light scattered by the concave portions 7 are completely different. That is, the light 8 scattered by the recess 7 enters the transparent flat plate 1, is refracted, and then exits to the outside of the transparent flat plate "1" again.

At this time, according to Snell's law, all the light is emitted from the transparent flat plate 1 parallel to the angle of incidence on the transparent flat plate 1. On the other hand, the component of the light 9 scattered by the convex portion 6 that is smaller than the critical angle is emitted to the lower part of the transparent flat plate, but the component that is larger than the critical angle is repeatedly totally reflected at the transparent flat plate/air interface and passes through the transparent flat plate 1. The concave and convex patterns are propagated, that is, the concave and convex patterns are pressed onto a transparent flat plate, and concavities and convexities are optically distinguished from each other by the difference in the scattering angle range of the scattered light on the transparent flat plate depending on the presence or absence of an air layer at the interface of the transparent flat plate. . As mentioned above, the light 8 scattered by the concave portion 7 is all emitted to the outside of the transparent flat plate 1, so the light vA9 propagating inside the transparent flat plate 1 is information from only the convex portion 6. If detected, pattern information of only the ridges of the fingerprint can be obtained.

When the light that has been totally reflected and propagated within the transparent flat plate 1 reaches the position of the hologram 3, it is guided into the hologram 3, diffracted by the hologram 3, and guided to the outside.
Photographed with camera 4 etc. In other words, pattern information from only the convex portions 6 can be observed as a fingerprint.

As shown in FIG. 4(a), among the scattered light at the convex portion 6,
It is also possible to make the light scattered at the critical angle or more directly enter the hologram 3 and take it out.

Note that the transparent flat plate 1 may be made of glass, plastic, or the like.

[Conventional technology]

By the way, when inputting personal information such as fingerprints in real time, if you can input while monitoring your own fingerprint image, you can check the input status such as whether your finger is placed in the correct position, which can be very helpful. I feel safe. FIG. 5 is a side view of a device capable of such monitoring, and FIG. 6 is a perspective view. A hologram Ild for detecting a fingerprint image or the like is provided on the back surface of the transparent flat plate 1, and a hologram Hm for monitoring is provided on the uneven surface information input section la side. Since the total reflected light 9 from the convex portion 6 is also incident on the monitor hologram Hm, the inputting person can confirm the input state of his or her fingerprint image by viewing the hologram Ha with his or her own eyes 14.

[Problem that the invention seeks to solve]

However, monitoring involves the possibility that one's personal information will be seen by others, photographed with the camera 15, etc., and taken away, and a replica (fake) created. If this replica is pressed against the uneven surface information input section 1a, it will be determined that they are the same person, and it can be misused.

A technical object of the present invention is to eliminate such problems in conventional uneven surface information input devices and to prevent the creation of replicas by recording monitor images with cameras or the like. .

[Means for solving problems]

FIG. 1 is a side view illustrating the basic principle of the uneven surface information input method according to the present invention. Reference numeral 1 denotes a transparent flat plate, and as in the case of FIG.
and leads to the monitor hologram H+w.

2 is a detection and monitoring light source for illuminating the uneven surface information input section 1a. In the present invention, this light source 2
In addition to this, a light source 16 for interference light is arranged on the back side of the monitor hologram Hm. This light source 16 has a different wavelength from that of the monitor light source 2 and generates light of a wavelength that is invisible to the naked eye, such as infrared light. Note that a plurality of light sources for interfering light may be provided so as to generate invisible light of various wavelengths.

[Effect]

In this way, the light source 1 on the back side of the hologram Hm for the monitor
6, when the interference light 17 such as infrared light is irradiated, some of the transmitted light passes upward together with the information light (therefore, the hologram HII+ generates interference light in addition to the light of the fingerprint image. , reaches the input person's eyes 14 and the camera 15. However, since the interference light is not visible light, the input person's eyes 14 see U
However, in the camera 15, in addition to the fingerprint image on the monitor hologram Hm, interference light is also incident and exposed, resulting in overexposure. As a result, the fingerprint image becomes unclear due to the interference light and is photographed.

[Example] Next, how the uneven surface information input method according to the present invention is actually implemented will be explained using an example.

In FIG. 1, the light source 16 of the interference light is placed on the back side of the monitor hologram Ha+, but as shown in FIG.
It can also be placed on the front side of the transparent flat plate 1.

In this case, the end of the transparent flat plate 1 is formed obliquely, the light source 16 is placed opposite the slope 19, and the interference light is made to enter the transparent flat plate 1 from the slope 19. A reflection hologram 18 is provided on the back surface of the transparent flat plate 1, facing the monitor hologram Hm. Therefore, the interference light 17 incident on the transparent flat plate 1 is reflected by the reflection hologram 18 toward the monitor hologram Hm, and the interference light 17 enters the transparent flat plate 1.
to illuminate. In this case, in order to prevent the interference light 17 from propagating toward the detection hologram Hd, the interference light 17 is propagated from a direction perpendicular to the page, and the interference light 17 and the scattering from the uneven surface information input section 1a are The optical paths of the lights 9 are made to intersect.

Infrared light is used as the interfering light, and He--Ne laser light is used as the detection and monitoring light.

When infrared light is used as the light source 16 for interfering light, the wavelength range of this infrared light is set to a range where the sensitivity of an imaging device such as a photographic film or a CCD exists. Further, the output of the light source 16 of the interference light is set to be quite strong so that when the monitor image is photographed, it becomes unclear. When monitoring with the human eye in this state, only the person's fingerprint image can be seen because the interfering light is not visible light. On the other hand, if an attempt is made to record a fingerprint image using the image sensor 15 which is sensitive to the infrared region, the contrast of the information light will be reduced due to the high bias caused by the infrared light, making it impossible to take back the monitor image.

Therefore, creating a replica becomes impossible.

Note that visible light having a different wavelength from that of the monitoring light source can also be used as the interfering light. In this case, there is an advantage in that psychological pressure is applied to those who are trying to record and misuse the monitor image, thereby discouraging them from recording and taking it home.

〔Effect of the invention〕

As described above, according to the present invention, even if someone tries to take a picture of the monitor image while inputting uneven surface information, the interference light will also be exposed, making it impossible to take a clear picture of the monitor image. It is possible to prevent the fingerprint image from being misused.

[Brief explanation of drawings]

Fig. 1 is a side view explaining the basic principle of the uneven surface information input method according to the present invention, Fig. 2 is a side view showing an embodiment of the method of the present invention, and Fig. 3 is an uneven surface information detection using a conventional prism. A side view of the device, FIG. 4 (al(b) is a side view of a conventional uneven surface information detection device using a transparent flat plate, FIG. 5 is a side view of a conventional monitor type uneven surface information input device, and FIG. 6 is a side view of the device. is a perspective view of the same device. In the figure, 1 is a transparent flat plate, 1a is an uneven surface information input section,
2 is a monitor and detection light source, 4 is a detector, Hd is a detection hologram, Hll is a monitor hologram, lO
15 shows an object to be detected (finger), 15 a camera, 16 a light source for interfering light, and 17 an interfering light.

Claims (1)

[Claims] A transparent flat plate (1) having an uneven surface information input section (1a) to which an uneven surface is crimped; , the light (9) incident on the transparent flat plate (1) at an angle greater than or equal to the critical angle,
Equipped with a detection hologram (Hd) that is guided to the outside by breaking the total reflection condition, and an uneven surface information input section (1a)
In a monitor-type uneven surface information detection device in which a second hologram (Hm) for extracting the totally reflected light from the transparent flat plate (1) is disposed on the side for monitoring, A method for inputting information on an uneven surface, characterized in that interference light having a wavelength different from that of a light source is made incident on the back surface of the second hologram (Hm).