JPH03161884A - Finger image input device - Google Patents

Abstract

PURPOSE:To shorten a time required up to the acquisition of a clear finger image by obtaining sufficiently much sweating within a short time even in an environment suppressing easy sweating from fingers by previously warming air in a cover. CONSTITUTION:When a power supply is turned on, a heater 16 is driven, air in a finger case 15 is warmed and the inside temperature of the case 15 is increased up to temperature capable of sufficiently sweating fingers. When a finger F is inserted into the finger case 15, the sweating of the finger F is immediately started by the high temperature in the case 15. Even in an environment suppressing necessary and sufficient sweating of the finger F, the adhesiveness of the finger F to a finger setting face T can be improve within a short time and user's waiting time required up to the acquisition of a clear finger image can be shortened.

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 authenticates an individual using a fingerprint image.

(Prior Art) Generally, as a method of a finger image input device often used in a personal authentication device, for example, as shown in FIG.
A finger F placed on a prism (finger rest) 1 is illuminated by a light source (illumination means) 2 through the prism 1, and an image of the finger F caused by the illumination from the source 2 is captured by a camera ( The image is taken by an imaging means (3).

In this case, on the contact surface between the finger F and the prism 1, the illumination light is totally reflected in the part where the finger F is not in contact with the finger F.
It is diffused where the two are in contact. That is, the surface of the finger F has many irregularities such as fingerprints and wrinkles at the joints. Therefore, by detecting the diffused and totally reflected light caused by the difference between contact and non-contact between the prism 1 and the finger F, a clear finger image can be obtained.

However, in the case of the finger image input device using the method described above, if the finger F placed on the prism 1 is dry, the adhesion between the finger F and the prism 1 will deteriorate, making it difficult to obtain a clear finger image. There were drawbacks.

Therefore, as shown in FIG. 5, the finger rest surface t of the prism 1 is
is covered with a cover 4, and the air inside the cover 4 is warmed by the heat emitted from the finger F, thereby promoting sweating of the finger F and increasing the adhesion between the finger F and the prism 1. There is.

However, this method has the disadvantage that it takes a considerable amount of time to obtain a clear finger image because it takes time to detect sweating of the finger.

(Problem 8 to be solved by the invention) As described above, in the conventional finger image input device, the air inside the cover is warmed by the heat from the fingers, and the temperature rise inside the cover promotes sweating of the fingers. However, it takes a long time to detect the perspiration of the finger, and it takes a considerable amount of time to obtain a clear image of the finger.

Therefore, the present invention provides a finger image input device that can obtain sufficient perspiration in a short time even in an environment where it is difficult to obtain perspiration from the fingers, and can shorten the time required to obtain a clear finger image. is intended to provide.

[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 on which the finger is placed, and a transparent finger rest on the finger rest. It has an illumination means for illuminating the placed finger, and an imaging means for capturing an image of the finger illuminated by the illumination means,
A cover for covering the finger placed on the finger rest, and a heat generating means for warming the air inside the cover, in which a finger image is input by contacting or non-contact between the finger and the finger rest. It is equipped with the following.

(Function) According to the present invention, the air inside the cover can be warmed in advance by the above-described means, so that the sweating effect on the fingers can be obtained in a short period of time.

(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 prism 12 as a finger rest is supported by the support base 11, and the angle formed by the surface R and the surface S with respect to the finger rest surface T is a right angle. The prism 12 has a light source (illumination means) 13 corresponding to the surface R.
is located. The illumination light from the light source l3 is made to enter the prism 12 at a predetermined angle that satisfies the total reflection condition on the finger rest surface T of the prism 12.

On the other hand, a camera 14 serving as an imaging means is arranged to face the surface S of the prism 12. This camera 14 detects the image of the finger F, that is, the diffused and totally reflected light caused by contact and non-contact of the finger F illuminated by the light source 13 with the finger placement surface T of the prism 12. .

A finger case (cover) 15 is provided on the support base 11 so as to cover the finger F placed on the finger rest surface 5T of the prism 12, for example, along with the prism 12.

The finger case 15 is shaped like a test tube roughly divided into two in the longitudinal direction, and is made of opaque plastic such as ABS resin (acrylonitrile-butadiene-styrene resin) or AS resin (acrylonitrile-butadiene-styrene resin). It is shaped by Su.

On the other hand, a heater 16 as a heat generating means is attached to the inner surface of the finger case 15. This heater 16 is
For example, it is made of a conductive heating sheet (conductive heating element) and is designed to warm the air inside the case 15.

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

First, assume that the device is powered on. At the same time, the heater 16 is activated to warm the air inside the finger case 15. Then, the temperature inside the finger case 15 is increased to such an extent that sweating of the finger F is sufficiently promoted.

6 In this state, the finger F is inserted into the finger case 15,
Assume that the finger is placed on the finger rest surface T of the prism 12. Then, this finger F is illuminated by light from the light source 13. The light from the light source 13 is totally reflected in a portion of the finger rest surface T that is not touched by the finger F, and diffusely reflected in a portion that is touched by the finger F. That is, the light is totally reflected at concave portions (non-contact portions) that do not come into contact with the finger rest surface T, such as fingerprints on the surface of the finger F or wrinkles at joints, and diffusely reflected at other convex portions (contact portions).

The camera 14 captures an image of the diffused and totally reflected light caused by the difference between contact and non-contact between the finger F and the finger rest surface T.

In this case, by inserting the finger F into the finger case 15, the finger F
Due to the high temperature inside the finger case 15, sweating begins immediately. Thereby, even in an environment where necessary and sufficient perspiration cannot be obtained, the adhesion of the finger F to the finger rest surface T can be improved in a short time.

Further, by forming the finger case 15 from opaque plastic, unnecessary incident light from the direction of the finger rest surface T can be blocked. Therefore, it is possible to reduce the incidence of disturbance light on the camera 14. As a result, a finger image that is clearer and has a higher S/N ratio can be obtained.

As described above, by warming the air inside the cover in advance, the sweating effect on the fingers can be achieved in a short period of time.

That is, while the temperature inside the finger case is rising, the finger is inserted into the finger case and placed on the prism. This promotes sweating in the fingers in a short period of time.

Therefore, even in environments where it is difficult to obtain a perspiration effect on the fingers, it is possible to obtain sufficient perspiration, making it easier to bring the fingers into close contact with the prism, and shortening the user's waiting time until a clear finger image is obtained. It is what it is.

In the above embodiment, a conductive heating element is used as the heating means, but the present invention is not limited to this, and other heating elements may also be used.

Further, the mounting position of the heat generating means is not limited to the inner surface of the finger case, but may be provided on the outer surface or both sides of the case.

It is also possible to use the same material as the heating element for the finger case itself.

Further, the heat generating means is not limited to a heat generating body such as a heater. For example, as shown in FIG. 2, air warmed by a dryer 21 may be slowly fed into the finger case 15. A similar effect can be obtained.

Alternatively, air warmed by a power source, lighting, etc. may be guided into the finger case through a duct or the like, without using a device such as a dryer.

Furthermore, as shown in FIG. 3, a sealing member 31 may be provided at the insertion opening for the finger F of the finger case 15 to further improve the perspiration effect of the finger F. In this case, the sealing member 31
For example, the sealing member 31 is made of elastic material made of rubber.
A cut is made to insert the finger F into the finger case 15, and this cut is normally closed to prevent air from entering and exiting the finger case 15.

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 air inside the cover can be warmed in advance, so that sufficient sweating can be achieved in a short time even in an environment where it is difficult to sweat the fingers. Thus, it is possible to provide a finger image input device that can shorten the time required to obtain a clear finger image.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a finger image input device showing one embodiment of the present invention, Figs. 2 and 3 show other embodiments of the invention, and Fig. 2 shows an example in which a hair dryer is used as a heat generating means. FIG. 3 is a side view illustrating a case in which a sealing member is provided in a finger case, and FIGS. 4 and 5 are for explaining the prior art and its problems. FIG. 11... Support stand, 12... Prism (finger rest),
10 1 3...Light source (illumination means) 14...Cameron (imaging means) 1 5...Finger case (cover) 16...Heater (heating means) F...Finger.

Claims (1)

[Scope of Claims] A transparent finger rest on which a finger is placed, illumination means for illuminating the finger placed on the finger rest, and imaging means for taking an image of the finger illuminated by the illumination means. The finger image input device inputs a finger image by contacting or non-contact between the finger and the finger rest, and the finger image input device includes a cover for covering the finger placed on the finger rest; A finger image input device characterized by comprising a heat generating means for warming.