JPH03194674A - Finger image input device - Google Patents

Abstract

PURPOSE:To obtain a finger image of high definition by attaching a warming means to a face other than the incidence face on which the light from an illuminating means of a finger placing face, with which a finger is brought into contact, of a finger placing base is made incident and an image pickup face of the finger image with an image pickup means. CONSTITUTION:A finger F is placed on a face (finger placing face) T interposed between faces S and R of an optical prism 1 as the finger placing base. A light source 2 and a camera 3 are arranged to face the face S of the prism 1. A heater 5 is attached to a face except the image pickup face of the finger image with the camera 3 on the face R (total reflected light absorbing face) of the prism 1. Thus, a vivid finger image of high definition is obtained without being affected by attachment of the heater 5.

Description

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

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

The most common methods for finger image input devices often used in this type of personal recognition device are the total internal reflection method using a prism and the optical path separation method. , Masahiko Hase: “Fingerprint information detection method using prism °, Journal of the Institute of Electronics and Communication Engineers Vol. 1.
J67-D Arashi 5, pp, 627-628 (1984
-4) is also introduced.

FIG. 3 shows a finger image input device that employs the optical path separation method.

That is, a light source (illumination means) is placed opposite the surface S of the optical prism (finger rest) 12 having a cross-sectional shape of a right isosceles triangle, which is one of the two sides intersecting at right angles in the cross section of the prism 12. 13 and camera (imaging means)
14 are arranged respectively, and another light shielding member 15 is coated to prevent light from entering there.

Then, with the finger F in contact with the finger rest surface T sandwiched between the surface R and the surface S, light from the light source (illumination means) 13 is incident from the surface S, so that the image of the finger F is displayed on the camera. 14. In this case, the surface (belly) of the finger F has countless irregularities such as fingerprints and wrinkles at the joints, and the light from the light source 13 is emitted only at the part where the finger F and the finger rest surface T are in contact. The light is diffused, and only a portion of this diffused light is captured by the camera 14 as a finger image.

By the way, the quality of the obtained finger image depends on the finger F and the prism 12.
It greatly depends on the degree of adhesion between the two.

Therefore, as shown in FIG. 4, a heater (heating means) 16 is attached to the surface of the prism 12, and the heater 16 warms the prism 12 to promote sweating of the finger F, thereby causing the finger F and the prism 12 to warm up. A device is being considered that improves the adhesion of the finger and makes it possible to obtain high-definition finger images.

However, when the heater 16 is attached to the surface S of the prism 12, there is a drawback that the heater 16 becomes an obstacle to capturing the finger image and illumination.

Furthermore, as shown in FIGS. 5 and 6, for example, when the heater 16 is attached to the finger placement surface T of the prism 12, the placement space for the finger F may be narrowed or the location may be restricted. There were drawbacks.

(To be solved by the invention: j4m) As mentioned above, in the conventional finger image input device, the heater is attached to the surface of the prism where the light source and camera are placed facing each other, so this Moreover, when it is attached to a finger resting surface, there is a drawback that the space for placing the finger is narrowed and the location is restricted.

Therefore, this invention improves the closeness between the finger and the finger rest without interfering with image capture or illumination, narrowing the space for placing the finger, or restricting the location. It is an object of the present invention to provide a finger image input device that can obtain a finger image.

[Structure 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 having a cross-sectional shape of a right-angled isosceles triangle; , comprising a heating means for warming the finger rest, an illumination means for illuminating the finger placed on the finger rest, and an imaging means for taking an image of the finger illuminated by the illumination means, In the device for inputting finger images by contacting and non-contacting with the finger rest, the heating means:
The finger rest is configured to be attached to a surface of the finger rest excluding a finger rest surface on which the finger comes into contact, an entrance surface on which light from the illumination means is incident, and an imaging surface of the finger image by the imaging means. ing.

(Function) The present invention uses the above-described means to eliminate the finger rest surface of the finger rest on which the finger comes into contact, the entrance surface on which light from the illumination means is incident, and the imaging surface of the finger image by the imaging means. Since the heating means is attached to the surface of the device, the attachment of the heating means does not interfere with image capture or lighting, narrow the space for placing the fingers, or limit the location. be.

(Embodiment N) An embodiment of the present invention will be described below 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 cross-sectional shape of a right-angled isosceles triangle, and its surface S and 1fiR
The angle between them is a right angle. Finger F is then placed on T (finger resting surface) which is sandwiched between S and surface R.

A light source 2 as an illumination means and a camera 3 as an imaging means are arranged on the prism 1 so as to face the surface S, respectively. Therefore, in this example,
The surface S serves as an incident surface and an imaging surface.

The camera 3 is located at a position where it does not capture the reflected light from other than the finger rest surface T of the prism 1, that is, it captures four parts of the light that is reflected by hitting unevenness such as fingerprints or wrinkles at the joints on the surface (belly) of the finger F. It is arranged in a position where the light that hits and is reflected cannot reach.

Further, the surface (total reflection light absorption surface) R of the prism 1 is coated with a black light shielding member 4 for absorbing light. A heater 5 as a heating means is attached to the black-coated surface R of the prism 1.

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

First, when the power of the apparatus is turned on, the power to the heater 5 is turned on and heating of the prism 1 is started.

Then, when the temperature of the finger rest T of the prism 1 is set to an appropriate temperature (temperature necessary for sweating), the finger F is placed on the finger rest surface T. Then, this finger F is promoted to sweat due to the heat received from the prism 1, and this causes the finger F to sweat.
The adhesion between the prism 1 and the prism 1 is improved.

In this state, the finger F on the finger rest surface T is illuminated by the light from the light R2 incident from the surface S of the prism 1. In this case, the surface (112) of the finger F has countless irregularities such as fingerprints and wrinkles at the joints. Therefore, the light from the light source 2 is diffusely reflected at the part where the prism 1 and the finger F are in contact, and is totally reflected or transmitted through the prism 1 at the other non-contact parts.

Then, on the finger rest surface T of the prism 1, the light source 2
Of the light that is reflected by hitting the unevenness of the finger F due to the illumination from the light source, the light that is totally reflected by hitting the open part that the finger F is not in contact with is guided to the surface R of the prism 1 and absorbed by the light shielding member 4. Ru.

On the other hand, the light that hits the convex portion that is in contact with the finger F is diffusely reflected at this portion, and a portion of the light is imaged by the camera 3. As a result, a high-quality (clear) finger image containing fingerprints and the like, in which the convex portions are bright and the open portions are dark, can be obtained.

Note that after the light transmitted through the prism 1 is diffusely reflected by the finger F, a portion of the light is returned to the prism 1 again, but is not captured by the camera 3.

As described above, the heater is attached to the total reflection light absorption surface of the prism, which absorbs the light that is totally reflected when it hits the open part that is not touched by a finger.

That is, the heater is attached to the surface of the prism other than the finger rest surface on which the finger comes into contact, the entrance surface on which light from the light source enters, and the surface where the finger image is captured by the camera. This eliminates the need for installing a heater that interferes with image capture or illumination, narrows the space for placing a finger, or restricts the location. Therefore, even in environments where necessary and sufficient perspiration cannot be obtained, it is possible to improve the adhesion of the fingers to the prism, and it is also possible to improve the adhesion of the fingers to the prism, and to achieve clearer, higher-quality images without being equally affected by the heater installation. This makes it possible to obtain detailed finger images.

In the above embodiment, the case where the heater 5 is attached to the surface R serving as the total reflection light absorption surface is explained as an example, but the present invention is not limited to this. For example, as shown in FIG. 2, the prism 1
The finger rest surface T1 on which the finger F comes into contact is attached to a surface U or surface V excluding the entrance surface on which the light from the light source 2 is incident and the surface S as the imaging surface of the finger image by the camera 3. You can do it like this.

Furthermore, the present invention can be applied to various finger image input devices that input, for example, a finger image of only a fingerprint portion, or a finger image of a finger metal body including wrinkles appearing at the first joint or the second joint. .

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, the finger rest
Since the heating means is attached to the surface other than the finger rest surface where the finger comes into contact, the entrance surface where light from the illumination means is incident, and the imaging surface of the finger image by the imaging means, it is difficult to capture images. A finger image that can obtain high-definition finger images by increasing the closeness between the finger and the finger rest without obstructing the lighting or narrowing the space where the finger can be placed. Input devices can be provided.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a finger image input device showing one embodiment of the present invention, FIG. 2 is a perspective view of a prism shown for explaining another embodiment of the invention, and FIGS. 3 to 6 are These are shown to explain the prior art and its problems. Fig. 3 is a configuration diagram of a finger image input device that employs the optical path separation method, and Fig. 4 is a configuration diagram of a finger image input device equipped with a heater. 5 and 6 are diagrams each showing an example in which a heater is attached to the finger resting surface of the prism. DESCRIPTION OF SYMBOLS 1... Optical prism (finger rest), 2... Light source (illumination means), 3... Camera (imaging means), 4... Light shielding member, 5... Heater (warming means), F...Finger.

Claims (1)

[Claims] A transparent finger rest having a cross-sectional shape of a right isosceles triangle, a heating means for warming the finger rest, an illumination means for illuminating the finger placed on the finger rest, and illuminated by the illumination means. In the finger image input device, the finger image input device includes an imaging means for capturing an image of a finger, and inputs a finger image depending on whether the finger is in contact with the finger rest or not, wherein the heating means is configured to , a finger image input device that is attached to a surface other than a finger rest surface on which the finger comes into contact, an entrance surface on which light from the illumination means is incident, and a surface on which the finger image is captured by the imaging means. Device.