JPH0395693A - Finger picture input device - Google Patents

Abstract

PURPOSE:To uniformly illuminate a whole finger, and to obtain clear finger picture by constituting a luminous body of a fluorescent lamp extending along the longitudinal direction of the finger placed on a finger placing surface. CONSTITUTION:When the lower part of the finger is brought into contact with the finger placing surface A of an optical prism 12, light from the luminous body 13 is total-reflected at a part not in contact with the finger F in the finger placing surface A, and is diffused-reflected at the part in contact with the finger, and is outputted from the surface C of the prism 12, and is image-picked up by a television camera 14. In this case, since a luminous body 13 consisting of the fluorescent lamp extending along the longitudinal direction of the finger F is arranged in the longitudinal direction of the finger F, the whole finger F is illuminated uniformly without unevenness by the light from the luminous body 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a finger image input device used, for example, in a personal authentication device that performs personal authentication using a finger image.

(Prior Art) In recent years, personal authentication devices have been devised that authenticate individuals by using an image of an individual's finger, for example, a fingerprint image including wrinkles at the joints of the finger, as personal identification information. In this type of personal authentication device, it is common to use an optical prism as a means for inputting a finger image.

As a method of using this prism, for example, "Transactions of the Institute of Electronics and Communication Engineers Vol. J68 D NO:3 (
As shown in "Comparison of Total Reflection Method and Optical Path Separation Method"), a method for detecting fingerprint information using a prism, there are the total reflection method and the optical path separation method.

As shown in FIG. 5, the total internal reflection method refers to the first surface A of an optical prism 1 having a cross-sectional shape of a right-angled isosceles triangle. facing the second surface B, which is one side of (a
) A light source (illumination means) 2 is disposed at a position shown in FIG. Then, the first surface A of the prism 1
With the finger surface of finger F in contact with the finger surface, the light from the light source 2 is incident on the second surface B of the prism 1, and the reflected light according to the unevenness of the finger surface of finger F, that is, the finger F and contact with prism 1,
Diffusion and total reflection light caused by the difference in non-contact is imaged by the imaging means 3 from the third element C of the prism 1.

On the other hand, in the optical path separation method, in the cross section of the optical prism 1 shown in FIG. 2 and an imaging means 3 are provided. A finger image is obtained by blocking the incidence of light from the second surface B of the prism 1 and capturing reflected light corresponding to the unevenness of the finger surface of the finger F by the imaging means 3. ing.

However, in a finger image input device that inputs a finger image using an optical prism, especially a finger image input device that inputs a fingerprint image including wrinkles at the joints, the entire finger is illuminated uniformly with one point light source because the finger is long and thin. It is difficult to do this, and the resulting finger image tends to be unclear.

(Problems to be Solved by the Invention) As described above, in the conventional device, the entire finger is illuminated with light from one point light source, so the obtained finger image tends to be unclear. was there.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a finger image input device that can uniformly illuminate the entire finger and obtain a clearer finger image.

[Configuration of the Invention (Means for Solving the Problem) In order to achieve the above object, the finger image input device of the present invention includes a transparent finger rest on which the finger is placed, and a transparent finger rest on the finger rest. The device includes an illumination device that is disposed along the longitudinal direction of the placed finger and uniformly illuminates the finger, and an imaging device that captures an image of the finger illuminated by the illumination device.

(Function) According to the present invention, the finger surface is evenly and uniformly illuminated by the above-described means.

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

FIG. 2 shows the external appearance of the finger image input device of the present invention. That is, an optical prism 12 serving as a finger rest is embedded in the upper surface (finger rest attachment surface) of the housing 11. In this case, the surface (first surface) of the prism 12 is at the same height as the upper surface of the housing 11.

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

In FIG. 1, the prism 12 has a cross-sectional shape of, for example, a right-angled isosceles triangle, and has a finger rest surface (first surface) A, a surface (second surface) B, and a surface (third surface). The angle formed with C is a right angle.

A light emitting body (illumination means) 13 is disposed on the prism 12 in correspondence with the surface B mentioned above.

The light emitting body 13 is composed of, for example, a fluorescent lamp extending along the longitudinal direction of the finger F placed on the finger placement surface A of the prism 12. The illumination light from the light emitter 13 is made to enter the prism 12 at a predetermined angle that satisfies the total reflection condition on the finger rest surface A of the prism 12.

On the other hand, on the surface C of the prism 12, a television camera 14 serving as an imaging means is arranged to face the prism 12. In this television camera 14, the image of the finger F, that is, the finger F illuminated by the light emitting body 13, is in contact or non-contact with the finger rest surface A of the prism 12 due to unevenness such as a fingerprint or wrinkles corresponding to the joints. The diffused and totally reflected light caused by this is detected.

Next, the operation of the above configuration will be explained.

First, it is assumed that the finger F is brought into contact with the finger rest surface A of the optical prism 12. Then, this finger F is illuminated by light from the light emitter 13 that enters from the surface B of the prism 12.

The light from the light emitting body 13 is transmitted to the finger F on the finger rest surface A.
It is totally reflected in areas that are not in contact with the light, and diffusely reflected in areas that are in contact with it.

The diffused and totally reflected light generated by the difference between contact and non-contact between the finger F and the finger rest surface A is reflected by the surface C of the prism 12.
The light is emitted from the camera and is imaged by the television camera 14.

In this case, since the light emitting body 13 made of a fluorescent lamp extending in the longitudinal direction of the finger F is arranged along the longitudinal direction of the finger F, the light from the light emitting body 13 covers the entire finger F evenly. It will be evenly illuminated. Therefore, it is possible to obtain a clear, high-quality finger image without unevenness between areas where the light is strong and areas where the light is weak.

As described above, in order to illuminate the finger placed on the optical prism, an elongated light emitting body is used and the light emitting body is arranged along the longitudinal direction of the finger. This improves the illumination efficiency for illuminating the finger surface, and the entire finger surface is uniformly illuminated. Therefore, the entire finger surface can be sufficiently illuminated, so that a clearer finger image can be obtained.

In the above embodiment, an elongated fluorescent lamp is used as the light emitting body, but as shown in FIG. ... may be arranged along the longitudinal direction of the finger F.

In addition, as shown in FIG. 4, in the cross section of the optical prism 12, a light emitter 13 and a television camera 14 are disposed at positions facing a third surface C, which is one of the two sides intersecting at right angles. The present invention can also be applied to a finger image input device using an optical path separation method. In this case, the surface B of the prism 12 is coated black and the camera 14 images only the diffused light of the part where the finger F and the finger rest A of the prism 12 are in contact, thereby obtaining a finger image with high contrast. be able to. Note that it is also possible to arrange a plurality of point light sources 15, . . . along the longitudinal direction of the finger F in the same manner.

Further, the optical prism is not limited to one having a right-angled isosceles triangular cross-sectional shape, but can also be applied to, for example, a right-angled triangular or other triangular cross-sectional shape, or even a prism having a cross-sectional shape other than a triangular shape.

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

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a finger image input device that can illuminate the entire finger uniformly and can obtain a clearer finger image.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a finger image input device showing one embodiment of the present invention, FIG. 2 is an external view of the finger image input device, and FIGS. 3 and 4 show other embodiments of the invention. Fig. 3 is a block diagram illustrating the case where a plurality of point light sources are used, Fig. 4 is a block diagram illustrating the case applied to an optical path separation type finger image input device, and Fig. FIG. 1 is a diagram shown to explain the prior art and its problems. 12... Optical prism (finger rest), 13... Light emitter (illumination means), 14... Television camera (imaging means)
, 15... point light source (illumination means), F... finger.

Claims (3)

[Claims] (1) A transparent finger rest on which to place a finger; an illumination means disposed along the length of the finger placed on the finger rest to uniformly illuminate the finger; and an illumination means that illuminates the finger uniformly. A finger image input device comprising: an imaging means for capturing an image of the finger. (2) a transparent finger rest on which to place a finger; an illumination means for uniformly illuminating the finger with a light emitting body extending along the longitudinal direction of the finger placed on the finger rest; and this illumination means a finger image input device comprising: an imaging means for capturing an image of the finger illuminated by the finger; (3) a transparent finger rest on which to place a finger; an illumination means for uniformly illuminating the finger using a plurality of light emitters arranged along the longitudinal direction of the finger placed on the finger rest; A finger image input device comprising: an imaging means for taking an image of the finger illuminated by the means.