JPH03100785A - Fingerprint sensor with sweating prompting function - Google Patents

Abstract

PURPOSE:To obtain an accurate fingerprint picture by providing a sweating prompting means on or near a fingerprint input face. CONSTITUTION:A sweating prompting means 10 consisting of a heating body is provided in the periphery of a fingerprint input face 1a. When a finger is brought into contact with the fingerprint input face 1a, the finger is heated by the sweating prompting means 10 and sweats. This sweat improves the optical contact between the finger and the fingerprint input face 1a, and the accurate fingerprint image free from breaks is formed on the image sensor of an optical system. Thus, the optical contact between the finger and the fingerprint input face is improved to obtain the accurate fingerprint image.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to improve the optical contact between a finger and a finger contact surface with respect to a fingerprint sensor with a perspiration promoting function used in a fingerprint verification device, and to improve the optical contact between a finger and a finger contact surface. A sweat promoting means consisting of a heating element is provided in the device to promote natural perspiration from within the body, thereby improving optical contact between the finger and the glass forming the fingerprint surface.

[Industrial Field of Application] The present invention relates to a fingerprint sensor with a perspiration promotion function used in a fingerprint identification device.

In recent years, as computers have been introduced into a wide range of social systems, system security has become a focus of interest among those concerned. Many questions have been raised about the security of ID cards and passwords, which have been used up until now to verify one's identity when entering a computer room or using a terminal. On the other hand, fingerprints have two major characteristics: they are unique for everyone, and they remain unchanged throughout life, so they are considered the most powerful means of identifying individuals, and much research and development has been conducted on simple personal identification systems using fingerprints. There is.

[Prior Art] In a personal verification system using fingerprints, a real-time input means for fingerprint images is important. Fingerprints are made up of uneven patterns, and it is necessary to detect these uneven patterns for fingerprint verification. FIG. 5 is a diagram showing an example of a conventional configuration of a fingerprint sensor optical system.

In the figure, 1 is a transparent body such as glass, the surface of which serves as a fingerprint input surface 1a. A finger 2 is in contact with the fingerprint input surface 1a as shown in the figure.

In this state, the light emitted from the light source 3 travels through the transparent body 1 and illuminates the fingerprint portion of the finger 2.

At this time, the ridges of the fingerprint are in contact with the fingerprint input surface 1a, but the valleys are not. When light is irradiated onto the fingerprint input surface 1a against which the finger 2 is pressed through the transparent body 1, the light is reflected and scattered by the finger surface.

Since the scattered light from the troughs (concave parts) of the finger first passes through the air and then enters the transparent body 1, there is no component that is totally reflected and propagated through the transparent body 1. Therefore, the valley (recess) of the finger
The scattered light passes through the transparent body 1 and exits to the outside. On the other hand, the reflected/scattered light from the ridges of the fingerprint directly enters the transparent body 1 from the finger 2 as a spherical wave, and part of it satisfies the condition of total reflection in the transparent body 1. It propagates through the interior through repeated total reflection.

A notch is formed at the end of the transparent body 1, and the propagating total reflection component light exits the transparent body 1 and enters the imaging optical system 14. The reflected light focused by the imaging optical system 14 enters the image sensor 5 and is converted into an electrical signal by the image sensor 5. The fingerprint image (ridge image) converted into an electrical signal is converted into digital data by an A/D converter (not shown), and further converted into binary data for fingerprint verification.

[Problems to be Solved by the Invention] However, when the scattered light from the contact area between the finger 2 and the fingerprint input surface 1a is imaged by an optical system, a part of the ridge pattern of the convex part is cut off, and the fingerprint image is distorted. Problems such as missing parts may occur. This causes a reduction in the matching rate of the fingerprint matching system. In order to eliminate such problems, a fingerprint sensor has been proposed in which an elastic film is coated on the fingerprint input surface 1a to improve optical contact between the finger and the glass surface (transparent body) that is the finger contact surface. However, this method has the problem that the elastic membrane is easily damaged and requires frequent maintenance.

The present invention has been made in view of these problems, and an object of the present invention is to provide a fingerprint sensor with a perspiration promoting function that can improve optical contact between a finger and a finger contact surface.

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. Components that are the same as those in FIG. 5 are designated by the same reference numerals. In the figure, 1a
1 is a fingerprint input surface against which a fingertip is brought into contact; 10 is a perspiration promoting means disposed around the fingerprint input surface 1a. The fingerprint input surface 1a becomes a finger contact surface. In the figure, sweating promotion means 10
is provided around the fingerprint input surface 1a, but the present invention is not limited to this, and may be provided on the fingerprint input surface 1a.

[Operation] When a finger (not shown) is brought into contact with the fingerprint input surface 1a, the finger is heated by the sweating promoting means 10 and sweats.

This sweat improves the optical contact between the finger and the fingerprint input surface 1a, and an accurate fingerprint image that is not cut off in the middle is formed on the optical system image sensor 5 as shown in FIG. . Therefore, according to the present invention, it is possible to improve the optical contact between the finger and the finger contact surface.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

Components that are the same as those in FIG. 1 are designated by the same reference numerals.

The illustrated embodiment shows an example in which a heating element 11 made of a heating wire is used as the perspiration promoting means 10. A heating element 11 is arranged along the fingerprint input surface 1a.

In such a configuration, when a finger (not shown) comes into contact with the fingerprint input surface 1a, the finger sweats due to heat from the heating element 11 arranged along the finger. This sweat improves the optical contact between the ridges of the finger and the fingerprint surface 1a, making it possible to obtain an accurate fingerprint image.

FIG. 3 is a block diagram showing another embodiment of the present invention. The embodiment shown in the figure has a transparent conductive film 12 on the surface of a transparent body 1.
was formed. In this case, the fingerprint input surface 1a is made of transparent conductive material H12. With this configuration, the surface itself that touches the finger 2 becomes hot, so
The finger 2 sweats, and this sweat improves the optical contact between the ridges of the finger and the fingerprint input surface 1a, making it possible to obtain an accurate fingerprint image.

FIG. 4 is a block diagram showing another embodiment of the present invention. In the embodiment shown in the figure, a far-infrared light source 13 that generates far-infrared rays is placed under a transparent body 1.

With this configuration, the finger in contact with the fingerprint input surface 1a is heated by the far infrared rays passing through the transparent body 1 and sweats. As a result, optical contact between the ridges of the finger and the fingerprint input surface 1a is improved, and an accurate fingerprint image can be obtained.

In the above description, a heating element, a transparent conductive film, and a far-infrared light source are used as an example of the perspiration promoting means 10, but the present invention is not limited to this, and the fingerprint input surface may be heated by some means. Any material may be used as long as it has the function of promoting sweating.

[Effects of the Invention] As described above in detail, according to the present invention, by providing a sweating promoting means on or near the fingerprint input surface, sweating from the fingers can be promoted, and the sweating between the fingers and the fingerprint input surface can be promoted. (finger contact surface) can be improved, and an accurate fingerprint image can be obtained.

[Brief explanation of drawings]

Fig. 1 is a principle block diagram of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the present invention, Figs.
The figure is a configuration diagram showing another embodiment of the present invention, and FIG. 5 is a diagram showing an example of the conventional configuration of a fingerprint sensor optical system. In FIG. 1, 1a is a fingerprint input surface, and 10 is a sweat accelerating means. 10 Fingerprint input screen Principle of the invention Figure 1

Claims (4)

[Claims] (1) A sweat accelerating means (10) consisting of a heating element is provided on or near the fingerprint input surface (1a) of the fingerprint sensor to promote natural perspiration from within the body, thereby forming a fingerprint input surface (1a) with the finger. A fingerprint sensor with a sweat-promoting function, characterized by being configured to improve optical contact with glass. (2) As the perspiration promoting means (10), the fingerprint input surface (
1a) The fingerprint sensor with a sweat-promoting function according to claim 1, characterized in that a heating element (11) is disposed around the periphery. (3) As the perspiration promoting means (10), the fingerprint input surface (
2. The fingerprint sensor with a perspiration promoting function according to claim 1, further comprising a transparent conductive film (12) disposed inside the fingerprint sensor (1a). (4) As the perspiration promoting means (10), the fingerprint input surface (
2. The fingerprint sensor with a perspiration promoting function according to claim 1, further comprising a far-infrared light source (13) disposed below the sensor (1a).