JPH06149983A - Fingerprint detection sensor - Google Patents

Abstract

PURPOSE:To realize a cost reduction as maintaining sensor performance in a fingerprint detection sensor used for the acquisition of an optical fingerprint image. CONSTITUTION:In the fingerprint detection sensor equipped with a transparent fingerprint input body provided with a recessed part to place a finger and a transparent light-conductor 3 which conducts the fingerprint image generated at the recessed part of the fingerprint input body to an image pickup sensor 9, the fingerprint input body is formed by coupling a first fingerprint input body 1a provided with the recessed part, and a second fingerprint input body 1b not provided with the recessed part, and also, the first fingerprint input body 1a is formed with a material with superior workability, and the second fingerprint input body 1b with a glass material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingerprint detection sensor used for obtaining an optical fingerprint image, and more particularly to a fingerprint detection sensor which can realize cost reduction while maintaining sensor performance.

Recently, a system using fingerprint collation as a personal identification method has been put into practical use. This fingerprint collation system obtains an optical fingerprint image of the person to be collated and judges whether or not the fingerprint image matches a pre-registered fingerprint image, so that the person to be collated is a real person. Then, a process for determining whether or not is executed. In order to realize such a fingerprint collation system, a fingerprint detection sensor for obtaining an optical fingerprint image is required, but in order to make the system practical, this fingerprint detection sensor is low cost. It is necessary to make it possible to realize in.

[0003]

2. Description of the Related Art A fingerprint has a concavo-convex pattern. As a fingerprint detection sensor for obtaining an optical fingerprint image of the concavo-convex pattern, the one having the structure shown in FIG. 5 has been conventionally used.

In the fingerprint detection sensor shown in FIG. 5, a transparent flat plate fingerprint input body 1 having a flat input surface 2 and a fingerprint image generated by a fingerprint placed on the input surface 2 are guided to an image sensor. The transparent light guide 3 (the shape includes a flat plate shape, a prism shape, etc.) is adopted. Here, in the figure, 4 is a finger placed on the input surface 2, 5 is a reflecting surface of the light guide 3, 6 is an illumination light source, 7 is a lens, 8 is a reflecting mirror, 9 is an image sensor, and 10 is FIG. The finger guide has a shape as shown in. The finger guide 10 is provided on the input surface 2
It is provided to define the placement position of the finger in.

When the person to be collated presses a finger against the input surface 2 at the time of adopting this configuration, the convex portion of the finger comes into contact with the input surface, but the concave portion does not come into contact with the input surface. When the input surface 2 against which the finger is pressed is irradiated with light, the scattered light from the fingerprint recess (valley line) once passes through the air and enters the light guide 3 via the fingerprint input body 1. Therefore, a component that propagates while being totally reflected in the light guide 3 is not generated. on the other hand,
The reflected / scattered light from the fingerprint convex part (ridge) is directly from the finger,
The light enters the fingerprint input body 1 as a spherical wave, and a part of the spherical wave satisfies the total reflection condition in the light guide 3 and propagates in the light guide 3 while repeating total reflection. An image of this total reflection component is formed on the image sensor 9 by an appropriate lens 7 to obtain a fingerprint image of the ridge pattern of the fingerprint convex portion on the image sensor 9.

However, in the fingerprint detecting sensor having such a configuration, since the input surface 2 is a flat surface, the contact area with the surface of the finger having an elliptic curved surface is limited. Therefore, recently, as shown in FIG. 7, a configuration has been adopted in which a transparent fingerprint input body 1 having an elliptical depression 11 similar to the surface of a finger is used.

[0007]

Conventionally, the fingerprint input body 1 having the depression 11 as shown in FIG. 7 uses a glass material as a material.

However, according to such a conventional technique, there is a problem that the cost of the fingerprint detection sensor cannot be reduced because it takes time to process the fingerprint input body 1 having the depression 11.

As one method of solving this, the depression 1
It is conceivable to adopt a method of forming the fingerprint input body 1 having 1 with a material having good workability such as plastic.

The fingerprint detecting sensor as shown in FIG. 7 is actually screwed from the lower side of the fingerprint input body 1 into the housing 12 as shown in FIG. 8 for ease of alignment and the like. 1
The method of fixing using 3 is adopted. If this method is adopted, the thickness of the housing 12 is required to some extent for mounting the screw 13, and if the thickness of the fingerprint input body 1 is reduced, it is difficult for the finger 4 to be placed. It will be necessary to some extent. However, if such a thick fingerprint input body 1 is formed of a material having good workability such as plastic, optical fingerprint is not homogenous, so that the fingerprint image formed on the image sensor 9 is distorted. There will be some problems.

Further, according to the prior art in which the glass material is used as the material of the fingerprint input body 1 as described above, the fingerprint input body 1 and the finger guide 10 cannot be integrally formed. There was also a problem that it was not possible to reduce the cost.

The present invention has been made in view of the above circumstances, and captures a transparent fingerprint input body 1 having a recess 11 for placing a finger and a fingerprint image generated by the finger placed in the recess 11. It is an object of the present invention to realize a low cost while maintaining the sensor performance of a fingerprint detection sensor provided with a transparent light guide 3 that leads to the sensor 9.

[0013]

FIG. 1 shows the principle configuration of the present invention. Here, the principle configuration of the present invention shown in FIG. 1A is based on the fingerprint input body 1 (the depression 11 shown in FIG. 7).
It is applied when the thickness of
The principle structure of the present invention shown in FIG. 1B is the fingerprint input body 1 of the type described in FIG. 5 (type having a flat input surface 2).
1 is applied when the thickness of the fingerprint input body 1 (type having the recess 11) of the type described with reference to FIG. 7 can be reduced.

In the figure, the same components as those described in FIGS. 5 and 7 are designated by the same symbols. In FIG. 1A, reference numeral 1a denotes a first fingerprint input body having a thin thickness, which is made of a transparent material having good workability, such as transparent plastic or transparent synthetic resin, for placing the finger 4 thereon. 11d, and preferably has a finger guide 10a for guiding the finger 4 in the peripheral portion of the depression 11a. Reference numeral 1b denotes a second fingerprint input body having a flat plate shape, which is made of a glass material and is arranged in close contact between the first fingerprint input body 1a and the light guide 3.

In FIG. 1 (b), reference numeral 1c is a fingerprint input body having a thin thickness, which is made of a transparent material having good workability, such as transparent plastic or transparent synthetic resin, for placing the finger 4 thereon. Has a flat input surface 2c, and further has a finger guide 10c for guiding the finger 4.

In FIG. 1 (c), 1d is a fingerprint input body having a thin thickness, which is made of a transparent material having good workability, such as transparent plastic or transparent synthetic resin, for placing the finger 4 thereon. 11d of this, and further, this depression 11
finger guide 10d for guiding the finger 4 to the peripheral portion of d
have.

[0017]

In the present invention whose principle configuration is shown in FIG.
The conventional fingerprint input body 1 having the depression 11 described in FIG.
A thin fingerprint input body 1a having a recess 11a;
The first fingerprint input body 1a is made of a material having good workability, and the second fingerprint input body 1b is made of glass. Since the fingerprint input body 1 can be easily manufactured at a low cost because it is formed of a material, optical homogeneity is maintained even when the thickness of the fingerprint input body 1 is required. By being maintained, the fingerprint image formed on the image sensor 9 is not distorted. Since the finger guide 10a can be formed integrally with the first fingerprint input body 1a, the fingerprint input body 1 can be manufactured more easily and at low cost.

On the other hand, in the present invention whose principle configuration is shown in FIG. 1B, the conventional fingerprint input body 1 having the flat input surface 2 described in FIG. 5 is represented by the fingerprint input body 1c in the figure. This fingerprint input body 1 is made of a material with good workability.
Since the finger guide 10c is integrally formed on the c, it is possible to easily manufacture a practical one at a low cost when the thickness is not required.

On the other hand, in the present invention whose principle configuration is shown in FIG. 1C, the conventional fingerprint input body 1 having the depression 11 described in FIG. 7 is processed as shown by the fingerprint input body 1d in the figure. Since the finger guide 10d is formed integrally with the fingerprint input body 1d while being formed of a good material,
When the thickness is not required, it becomes possible to easily manufacture a product at a practical level at low cost.

As described above, according to the present invention, the transparent fingerprint input body 1 having the recess 11 for the fingerprint detection sensor to place the finger, and the image sensor for picking up the fingerprint image generated by the finger placed in the recess 11 are provided. In some cases, it is possible to realize cost reduction while maintaining the sensor performance of the fingerprint detection sensor when it is configured with the transparent light guide 3 that leads to 9.

[0021]

EXAMPLES The present invention will be described in detail below with reference to examples. FIG. 2 illustrates one embodiment of the present invention. In the figure,
The same components as those described in (a) are denoted by the same symbols.

Reference numeral 3a denotes a prism body formed of a glass material, which constitutes the light guide 3 described in FIG. 1A, and an image sensor for reflecting / scattering light reflected from a fingerprint convex portion (ridge). In addition to propagating in the arrangement direction of 9, the scattered light from the fingerprint concave portion (valley line) propagates in a direction other than the arrangement direction of the image sensor 9, and 14 is an antireflection film coated on the prism body 3a.

According to this embodiment, the conventional fingerprint input body 1 having the depression 11 described with reference to FIG. The fingerprint input body 1b and the first fingerprint input body 1a are made of a material having good workability, and the second fingerprint input body 1b is made of a glass material. Therefore, the fingerprint input body 1 can be easily manufactured at a low cost, and even when the thickness of the fingerprint input body 1 is required, the optical homogeneity can be maintained, so that the image sensor 9 can be manufactured. Distortion does not occur in the formed fingerprint image. Since the finger guide 10a can be integrally formed on the first fingerprint input body 1a, the fingerprint input body 1 can be manufactured more easily and at low cost.

3 and 4 show another embodiment of the present invention. In the figure, the same components as those described in FIG. 1C are indicated by the same symbols. In the example of FIG.
A characteristic point is that a total reflection surface portion 15 is newly provided on the lower surface of the light guide 3 having a flat plate shape. The total reflection surface portion 15 is composed of another component such as transparent plastic and has a convex curved surface. According to the configuration of the present invention shown in FIG. 1C, the reflected / scattered light from the fingerprint convex portion (ridge) may not satisfy the total reflection condition on the lower surface of the flat plate-shaped light guide 3. According to the embodiment of FIG. 3 having the total reflection surface portion 15, the total reflection condition can be satisfied.

On the other hand, the embodiment of FIG. 4 is characterized in that a distortion correction optical system indicated by 16 is newly provided. The distortion correction optical system 16 is provided, for example, between the lens 7 and the reflecting mirror 8. According to the configuration of the present invention shown in FIG. 1C, since the fingerprint image formed on the image sensor 9 may be distorted by having the depression 11d, the distortion correction optical system 16 shown in FIG. According to the embodiment of, it becomes possible to correct such distortion.

[0026]

As described above, according to the present invention,
Sometimes when the fingerprint detection sensor is composed of a transparent fingerprint input body with a recess for placing a finger and a transparent light guide that guides the fingerprint image generated by the finger placed in the recess to the image sensor. , While maintaining the sensor performance of the fingerprint detection sensor,
The cost can be reduced.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is an example of the present invention.

FIG. 3 is another embodiment of the present invention.

FIG. 4 is another embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional technique.

FIG. 6 is an explanatory diagram of a finger guide.

FIG. 7 is an explanatory diagram of a conventional technique.

FIG. 8 is an explanatory diagram of a mounted state of a fingerprint detection sensor.

[Explanation of symbols]

 1a 1st fingerprint input body 1b 2nd fingerprint input body 1c Fingerprint input body 1d Fingerprint input body 2c Input surface 3 Light guide body 4 Finger 5 Reflective surface 6 Illumination light source 7 Lens 8 Reflector 9 Image sensor 10a Finger guide 10c Finger Guide 10d Finger guide 11a Indentation 11d Indentation

Claims (6)

[Claims] 1. A fingerprint detection sensor comprising: a transparent fingerprint input body having a depression for placing a finger; and a transparent light guide body for guiding a fingerprint image generated by the depression of the fingerprint input body to an image sensor. The fingerprint input body is the first fingerprint input body (1a) having a depression.
And a second fingerprint input body (1b) having no dent, and the first fingerprint input body (1a) is made of a material having good processability, and the second fingerprint input body is formed. A fingerprint detection sensor characterized in that the body (1b) is made of a glass material. 2. The fingerprint detection sensor according to claim 1, wherein a finger guide (10a) for guiding a finger is integrally formed in the peripheral portion of the depression of the first fingerprint input body (1a). , Characteristic fingerprint detection sensor. 3. The fingerprint detection sensor according to claim 1, wherein the first fingerprint input body (1a) is made of plastic or elastic material. 4. A fingerprint detection sensor including a transparent fingerprint input body having an input surface for placing a finger, and a transparent light guide body for guiding a fingerprint image generated by the input surface of the fingerprint input body to an image sensor. 2. The fingerprint detection sensor, wherein the fingerprint input body is formed of a material having good workability and a finger guide for guiding a finger is integrally formed on the fingerprint input body. 5. A fingerprint detection sensor comprising a transparent fingerprint input body having a recess for placing a finger and a transparent light guide body for guiding a fingerprint image generated by the recess of the fingerprint input body to an image sensor. A fingerprint detection sensor, characterized in that the fingerprint input body is formed of a material having good workability, and a finger guide for guiding a finger is integrally formed in the peripheral portion of the depression of the fingerprint input body. 6. The fingerprint detection sensor according to claim 4, wherein the fingerprint input body is formed of plastic or elastic material.