JPH03194677A - Finger image input device - Google Patents

Abstract

PURPOSE:To obtain a finger image of high quality by irradiating the bulb of a finger with light from the perpendicular direction. CONSTITUTION:A prism 1 is provided with a light source 2 closely brought into contact with a parallel face U facing a finger placing face T, and a finger F placed on the finger placing face T is illuminated with this light source 2 from the perpendicular direction (just below). When the finger F is placed on the finger placing face T of the prism 1, the finger F is illuminated with the light from the light source 2. In this case, the bulb of the finger F is perpendicu larly irradiated by the light source 2, and the finger F is brightly and effectively illuminated. The light thrown to projecting parts, with which the finger F is brought into contact, out of the light which is thrown to recessed and projecting parts of the finger F by illumination from the light source 2 and is reflected by them on the finger placing face T of the prism 1 is diffused by these project ing parts, and the image of a part of this light is picked up by a camera 3. Thus, a vivid finger image including fingerprint or the like is obtained where projecting parts are bright and recessed parts are dark.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention] (Industrial Application Field) The present invention relates to a finger image human power device used in a personal authentication device that authenticates an individual using a fingerprint, for example.

(Prior Art) In recent years, personal authentication devices that use finger images such as fingerprints as personal identification information have been developed.

In this type of personal recognition device, the most common method of finger image input device is to use a prism (for example, IEICE paper 2VO
1, J 68-D Na3 (Refer to "Comparison of total internal reflection method and optical path separation method", a method for detecting fingerprint information using a prism).

FIG. 2 shows a finger image manual device that employs the total internal reflection method. In the case of this method, the finger rest surface T of the optical prism (finger rest) 12 has a cross-sectional shape of a right-angled isosceles triangle.
With the finger F in contact with the prism 12, light from the light source (illumination means) 13 is incident on the surface R, which is one of the two sides intersecting at right angles in the cross section of the prism 12, and then on another surface S. An image of the finger is taken by a camera (imaging means) 14 placed opposite to the finger.

On the other hand, finger image input devices that use the optical path separation method
As shown in FIG. 3, a light source 13 and a camera 14 are respectively disposed facing the surface S of the optical prism 12, and a light shielding member 15 is provided on the surface R to prevent light from entering there.
An image of the finger is taken from the surface S.

However, in the case of the above two finger image input devices,
Since the finger F is illuminated obliquely, the illumination efficiency is poor and it is difficult to obtain a high-quality finger image. In particular, in a finger image input device that uses the optical path separation method, it is necessary to place the camera 14 in a position where it does not receive light that is reflected by hitting four parts of the unevenness such as fingerprints on the surface of the finger or wrinkles at the joints. . For this reason, if the light source 13 is moved too close to the prism 12 in order to improve the efficiency of illumination, this will enter the field of view of the camera 14 and interfere with imaging.

(Problems to be Solved by the Invention) As mentioned above, in the conventional finger image human-powered device, the finger is illuminated from an angle, so the illumination efficiency is poor and it is difficult to obtain a high-quality finger image. There was a drawback.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a finger image human-powered device that can obtain high-quality finger images without interfering with imaging.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, in the finger image input device of the present invention, the right angle part of the right isosceles triangle is arranged substantially parallel to the finger rest surface. A transparent finger rest formed of a transparent finger rest, an illumination means for illuminating a finger placed on the finger rest from a parallel surface side formed on the finger rest, and a finger illuminated by the illumination means. , an imaging means for capturing an image of a finger in contact with the finger rest surface and in a non-contact state from a third surface of the finger rest excluding the finger rest surface and a parallel surface.

(Function) This invention uses the above-described means to apply light to the pads of the fingers in a vertical direction, thereby improving the efficiency of illumination and making it possible to illuminate the fingers more brightly and effectively. It is something.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a finger image input device of the present invention.

That is, the optical prism 1 as a finger rest has a so-called trapezoidal cross-sectional shape, which is formed by forming the right angle part of a right-angled isosceles triangle substantially parallel to the finger rest surface T. In this case, the four sides ad, bc, a"d-, b on prism 1
The lengths of "C" are all made equal.

A light source 2 serving as illumination means is disposed on the prism 1 in close contact with a hitting surface U 11' facing the finger rest T. This light source 2 is a finger F placed on the finger rest surface T.
is illuminated from the vertical direction (directly below).

On the other hand, a camera 3 serving as an imaging means is arranged to face a surface (third surface) S of the prism 1, for example, aa"dd". In this case, the camera 3 detects that the surface of the finger F<I! Among the light that is reflected by hitting the unevenness such as fingerprints and wrinkles of the joint parts in I), the light that is reflected by hitting the four parts is placed in a position where it cannot reach.

Further, the surface R of the prism 1, for example, where bb=cc- is coated with a black light shielding member 4 for absorbing light.

Next, the operation in such a configuration will be explained.

For example, assume that the finger F is placed on the finger placement surface T1 of the prism 1. Then, this finger F is illuminated by light from the light source 2. In this case, since the light source 2 is provided in close contact with the parallel plane υ formed almost parallel to the finger rest surface T, it is possible to apply light perpendicularly to the pad of the finger F, and to The finger F can be illuminated brightly and effectively.

Then, on the finger rest surface T of the prism 1, the light source 2
Of the light that hits the unevenness of the finger F and is reflected by the illumination, the light that hits the white part where the finger F is in contact is diffused in this part, and a part of it is imaged by the camera 3. As a result, a high-quality (clear) finger image is obtained in which the convex bones are bright, the openings are dark, and fingerprints are included.

Note that the manually generated finger image may include only the fingerprint portion, or may target the finger metal body including wrinkles appearing at the first joint and the second joint.

As described above, by applying light to the pad of the finger in a vertical direction, the efficiency of illumination is improved and the finger can be illuminated more brightly and effectively.

That is, the finger is illuminated from the parallel surface side that is formed substantially parallel to the finger placement surface of the prism.

This allows light to be applied to the pad of the finger from a direction perpendicular to the finger pad. Therefore, the efficiency of illumination can be improved without interfering with imaging, and the finger can be illuminated more brightly and effectively, making it possible to obtain a high-quality finger image.

Furthermore, since the light source is arranged in close contact with the parallel plane, the illumination effect is further improved and the device can be made smaller.

It goes without saying that various other modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As detailed above, according to the present invention, since the finger is illuminated from the parallel surface side that is formed substantially parallel to the finger rest surface of the finger rest, it does not obstruct imaging. It is possible to provide a finger image human-powered device that can obtain high-quality finger images without having to do anything.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a finger image input device showing an embodiment of the present invention, Figs. 2 and 3 are shown to explain the prior art and its problems, and Fig. 2 shows the total internal reflection method. FIG. 3 is a block diagram of a finger image input device that employs the optical path separation method. L... Optical prism (finger rest), 2... Light source (illumination means), 3... Camera (imaging means), F... Finger.

Claims (1)

[Claims] A transparent finger rest formed by forming the right angle part of a right-angled isosceles triangle substantially parallel to the finger rest surface, and a finger placed on this finger rest surface from the parallel surface side formed on the finger rest. A third surface of the finger rest excluding the finger rest surface and the parallel surface, which is a finger image based on the difference between the illumination means for illuminating and the finger illuminated by this illumination means, in contact with the finger rest surface and non-contact with the finger rest surface. What is claimed is: 1. A finger image input device comprising: an imaging means for capturing an image from a finger;