JPH11250230A - Finger sack for reading fingerprint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a finger sack for reading fingerprint with stable fingerprint readability to be used for each individual. SOLUTION: This is a finger sack 77 for reading fingerprint to be applied in a fingerprint reading device 10 in which a fingerprint reading face 44 being an optical member on which fingerprint is placed is irradiated with lights, the lights are fully reflected on the fingerprint reading face 44, and return lights including the picture information of fingerprint are received so that the fingerprint can be optically read. In this case, this finger sack is made of materials having almost the same refractive index as that of the optical member, and this finger sack is mounted on a finger F whose fingerprint should be collected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating a fingerprint reading surface of an optical member on which a fingerprint is placed with light, and totally reflecting the fingerprint reading surface to receive return light including fingerprint image information. The present invention relates to a finger cot for fingerprint reading applied to a fingerprint reading device for optically reading a fingerprint.

[0002]

2. Description of the Related Art With the spread of information processing technology in recent years, there has been a problem in system management and ensuring security. At present, for example, in the field of information processing, it is generally adopted that a user directly inputs a personal identification number or identifies each individual using a magnetic card or the like in which a personal identification number or the like is recorded. In addition, in the personal living environment, attention has been paid to the safety of use of keys such as houses, cars, lockers, and the like. However, in the conventional security measures, there is a risk that the user forgets the personal identification number, or the key or card is lost, stolen or forged. Therefore, as a remedy, we focus on fingerprints that are unique to individuals and do not change for life, and collate the fingerprint pattern of the finger with a pre-recorded reference fingerprint pattern to ensure system management and security. It has been proposed that

As an example, consider a case in which a fingerprint collation device for reading such fingerprints is provided on a door on the driver's seat side of an automobile. In this case, the user who has registered the fingerprint pattern contacts the fingerprint of the finger with the fingerprint reader, and the fingerprint reader reads the fingerprint. As a result of the reading, when the fingerprint of the finger matches the fingerprint pattern for reference, the user can unlock the door on the driver's seat side and open the door. As described above, it is important to read and discriminate a fingerprint of a finger in order to determine whether or not the user is the person.

Conventionally, as a method for optically detecting a fingerprint of a person, a finger is brought into close contact with a glass surface of a prism, and light and dark generated by a change in light (specular reflection and irregular reflection) in which light from a light source is reflected on the contact surface. Is connected to a charge-coupled device (CC) via an imaging lens system.
D).

FIG. 9 and FIG. 10 show a conventional fingerprint reader. 9 and 10 includes an incandescent lamp 1000, a prism 1001, an optical lens 1002, C
It has a CD camera (charge-coupled device camera) 1003 and a processing unit 1004. The finger F is placed on the fingerprint reading surface 1005. The incandescent lamp 1000 is a point light source. The light of the incandescent lamp 1000 irradiates the fingerprint reading surface 1005 of the prism 1001, and the light totally reflected by the fingerprint reading surface 1005 passes through the optical lens 1002 to the CCD camera 1003. It is designed to take in. The light captured by the CCD camera 1003 is converted into an optical-electrical signal, and a predetermined process is performed by the processing unit 1004. When the fingerprint of the finger F matches the reference fingerprint, the external output signal 1006 is output to the door, for example. Is supplied to an operation target 1007 such as a lock device. Thus, the locked state of the operation target 1007 is released.

[0006] Here, the refractive index of the prism 1001 formed on the fingerprint reading surface 1005 at the light source wavelength and the fingerprint reading surface 1
The following total reflection condition is satisfied at the interface of the fingerprint reading surface 1005 due to the incident angle of the light beam to the 005. IT = sin ⁻¹ (n ′ / n) where IT is the incident angle of the light beam, n is the refractive index of the medium on the incident side,
n ′ is the refractive index of the medium passing therethrough.

For example, a conventional prism 10 shown in FIG.
Assuming that the refractive index at the light source wavelength of 01 is 1.5 and the refractive index of the air as the medium on the passing side is 1, IT is about 41.8 degrees. That is, such a rectangular prism 100
1, the incident angle of the incident optical axis on the fingerprint reading surface 1005 is approximately 45 degrees, and when nothing is in contact with the fingerprint reading surface 1005, all the light is reflected to satisfy the total reflection condition, and the fingerprint is reflected. When a substance having a refractive index higher than 1.06 comes into contact with the reading surface 1005, the light beam passes through the interface because the condition of total reflection is not satisfied. The passed light flux is absorbed or scattered by the skin or the like, so that the fingerprint reading surface 10
The intensity of the reflected light changes corresponding to the contact portion and the non-contact portion at 05, and as a result, light including image information of a grayscale image corresponding to the unevenness of the fingerprint is obtained. That is, the contact portion becomes irregularly reflected and becomes dark, and the non-contact portion becomes specularly reflected and becomes bright.

By the way, the shape of the fingerprint of the human body does not change significantly depending on the environment or physical condition, but the state of the surface is not constant. For example, it is known that sweating from a fingertip decreases when the outside air temperature is low or due to extreme stress. This is due to the fact that sufficient moisture or lipid cannot be present between the finger and the fingerprint reading surface, and that the light is transmitted from the contact portion and that a reflection image (dark portion) is formed due to deviation from the total reflection condition. Means to inhibit. That is, depending on the environment or the physical condition of the user, the accuracy of fingerprint reading is reduced, and the reliability of the fingerprint reading device is impaired. In order to improve the reading instability of the fingertip, for example, as shown in FIG.
A method for stabilizing fingerprint reading performance is disclosed in Japanese Unexamined Patent Publication No. 2-17029.
No. 1 discloses this. Alternatively, in order to improve such reading instability of the fingertip, the heating member 900 is heated as shown in FIG.
A method has been proposed in which sweating of a finger is promoted by heating 005.

[0009]

However, in such a conventional measure for stabilizing a fingerprint read image, FIG.
In the case of (1), when the elastic thin film 800 is scratched or stained, the fingerprint reading performance is deteriorated. Therefore, the surface of the elastic thin film 800 is covered with a harder substance, or every time the scratch or stain is generated. It needs to be replaced. In the method using the heating member 900 as shown in FIG. 10, an energy source or a judgment mechanism for judging heating is required, the structure becomes complicated, and an increase in price is unavoidable. In addition, there is a tendency in recent days to avoid physical indirect contact with others and to carry out antibacterial or sterilizing treatment on objects that are touched by unspecified persons to maintain cleanliness. It is not clear whether the reasons are unconscious defense against unidentified microorganisms in society or the appearance of a mere epidemic or individualism, but it is becoming a clear social phenomenon. One problem is also encountered in a reading device. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, to provide a finger cot for fingerprint reading which can stabilize fingerprint reading performance and can be used for each individual.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to irradiate light on a fingerprint reading surface of an optical member on which a fingerprint is placed, and totally reflect the light on the fingerprint reading surface to obtain image information of the fingerprint. A fingerprint sack for fingerprint reading applied to a fingerprint reader for optically reading a fingerprint by receiving return light including: a material having a refractive index substantially equal to the refractive index of the optical member. This is achieved by a finger cot for reading fingerprints, which is attached to a finger to be fingerprinted.

According to the present invention, a fingerprint is optically illuminated by irradiating light to a fingerprint reading surface of an optical member on which the fingerprint is placed, totally returning the light to the fingerprint reading surface, and receiving return light containing image information of the fingerprint. 5 is a finger cot for reading a fingerprint applied to a fingerprint reading device for reading a finger. The finger cot is made of a material having a refractive index substantially the same as the refractive index of the optical member, and is designed to be attached to a finger from which a fingerprint is to be collected.
Thus, since the refractive index of the finger cot is substantially the same as the refractive index of the optical member, the light irradiated on the fingerprint reading surface passes through the finger sack to return light including the image information of the fingerprint corresponding to the fingerprint. Can be formed. If this finger cot is used, the fingerprint can be brought into close contact with the fingerprint reading surface, so that the fingerprint reading performance is also improved. In addition, since the finger sack needs to be prepared for each individual, it is possible to avoid a phenomenon in which the fingerprint of the finger directly or indirectly touches the fingerprint matching surface during fingerprint matching. It can also improve the cleanliness of use.

In the present invention, preferably, if information related to fingerprint reading is recorded in the finger cot, for example, information of an individual using the finger sack can be stored in advance, and other information such as fingerprint information can be stored. The personal information and the like can also be obtained from the fingerprint reader. In the present invention, it is preferable that only the portion of the finger cot that contacts the fingerprint can be replaced, so that even if the portion is damaged or stained, only the portion that contacts the fingerprint can be replaced. Is economical.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows a preferred embodiment of the fingerprint reader of the present invention. The fingerprint reader 10 has a connection cable 12. The fingerprint reading apparatus 10 has a case 14, and the case 14 preferably has a guide portion 16 for guiding and positioning the finger F at an optically appropriate position. This guide section 16
For example, it has a concave shape conforming to the shape of the finger F, into which the fingerprint 20 of the finger F is fitted. This guide part 16
Is formed on the inclined portion 22 of the case 14.

FIG. 2 shows an example of the internal structure of the fingerprint reader 10 of FIG. Case 1 of fingerprint reader 10 of FIG.
4, a semiconductor laser 30 as a light source, a prism (optical member) 34, an optical lens 36, a CCD camera 3
8, a signal processing unit 40 and the like. Semiconductor laser 30
Is a point light source, is monochromatic, and has high light conversion efficiency, so it is desirable to employ such a semiconductor laser. The wavelength of the light beam 42 emitted from the semiconductor laser 30 is, for example, 780 nm.

The prism 34 is a prism preferably having a triangular cross section, and is made of, for example, glass or plastic. Fingerprint reading surface 4 of prism 34
4 is exposed outside the case 14 and constitutes the bottom surface of the guide portion 16 as shown in FIGS. 1 and 2. On the fingerprint reading surface 44, the contact portion 20A of the fingerprint 20 of the finger F
And the non-contact portion 20B are closely mounted.

The luminous flux 42 of the semiconductor laser 30 shown in FIG. 2 is totally reflected on the fingerprint reading surface 44, is bent by approximately 90 °, and is guided to the optical lens 36. The optical lens 36
An imaging optical system for the parallel light 46,
Is to lead to. The CCD camera 38 is an imaging device that converts the parallel light 46 into a light-electric signal.

An image signal S1 output from the CCD camera 38 is supplied to an image processing unit 50 of the signal processing unit 40. The image processing unit 50 binarizes the image signal S1 based on, for example, a predetermined threshold value, and
Is processed so that the contact portion 20A and the non-contact portion 20B can be clearly separated by a signal. Thus, the image processing unit 5
The image signal S2 processed at 0 is stored in the memory 52. The image signal S2 stored in the memory 52 is compared with a reference fingerprint stored in advance by a matching unit 54.
To determine whether the fingerprint 20 matches the reference fingerprint. The collation unit 54 is, for example, C
A PU (Central Processing Unit) or the like can be used. If the collation result is successful, the external output signal S3 is sent to the operation target 60 via the connection cable 12 via the input / output unit 56. The operation target 60 is, for example, a lock device for a door of a building, a lock device for a door on the driver's seat side of an automobile, or the like. When the external output signal S3 is sent to the operation target 60, the locked state of the lock device on the operation target 60 can be released.

In FIG. 2, when the finger F is placed along the guide portion 16 on the fingerprint reading surface 44,
This is to use a finger sack 77 as shown in FIGS. The material of the finger cot 77 is made of, for example, natural rubber such as latex or a polymer film having similar characteristics. This reading finger sack 77 has an insertion opening 77A and a closing portion 77B.
The finger F is inserted into the closing portion 7 by inserting it through the insertion portion 77A.
Stop at 7B. Thereby, the reading finger sack 77 can almost cover the area of the fingerprint 20 of the finger F. The thickness of the finger sack 77 is, for example, 20 μm to 30 μm.
μm, and the refractive index of the material of the finger sack 77 is almost the same as the refractive index of the prism 36 which is an optical member. This is because if there is a difference in the refractive index between the fingerprint reading surface of the prism 34 and the boundary surface between the finger sack 77 and the finger sack 77, a light beam is reflected, which results in a false image and lowers the reading performance.
Incidentally, the reflectance γ of the vertically incident light at the interface between the two media having the refractive indices n1 and n2 is substantially (n1−n2 / n1).
+ N2) ² . In any case, the finger sack 77 must be made of a material having elasticity, flexibility and adhesion.

FIG. 4 shows the fingerprint 20 and the like of the finger F inserted into the finger cot 77. Non-contact part 2 on fingerprint 20
0B and the contact portion 20A, but the non-contact portion 20B has the fingerprint 2
0, and the contact portion 20A is a convex portion of the fingerprint 20. The finger sack 77 has elasticity, flexibility and adhesion, but is curved in a concave shape so that a part of the finger sack 77 is adapted to the relatively large non-contact portion 20B. On the other hand, in the portion where the protrusions 20A are arranged, the finger sack 7
The portion 7 closely adheres along the fingerprint reading surface 44 of the prism without following.

Thus, the light beam 4 from the light source 30 shown in FIG.
2 is totally reflected at the portion corresponding to the non-contact portion 20B and returns to the optical lens 36 side in FIG. 2 and returns as light RL. On the other hand, in the portion corresponding to the contact portion 20A, the light beam 42 cannot be totally reflected and a part of the light beam proceeds to the optical lens 36 side as return light, but almost all is absorbed. Thus, the finger sack 77 made of a material having flexibility, elasticity and adhesion, such as latex or silicon, adheres closely to the profile in the large non-contact portion 20B, but in the small non-contact portion or contact portion. , Along the fingerprint reading surface 44. That is, the fingerprint reading surface 44 originally serves as a convex portion of the fingerprint.
In the portion where the finger sack 77 contacts the finger sack 77 because the convex contact portion 20A of the fingerprint and the finger sack 77 and the fingerprint reading surface 44 are integrally in contact with each other. It is absorbed by the finger through the material.

On the other hand, in the non-contact portion 20B where an air layer is formed between the fingerprint 20 and the material of the finger sack 77 or the material of the finger sack and the reading surface, the light flux cannot reach the finger surface and is totally reflected. I will. Thus, the finger and the fingerprint reading surface 44
By interposing the thin-film finger sack 77 as described above, for example, the unevenness of the fingerprint can be converted into a gray-scale image of the reflected image. Furthermore, even if there is no moisture or lipid on the finger surface, if the material of the finger and the finger sack 77 has sufficient adhesiveness, the fingerprint reading performance will be stable, and the fingerprint reading performance will be reduced due to the environment or the user's physical condition. Nothing.

The optical characteristics of the material of the finger sack 77 are, as described above, preferably to have substantially the same refractive index as the prism 34, which is an optical member for reading, but to have a slightly different refractive index. Although it is possible even with the ratio, it is possible to increase the contrast between light and dark depending on the amount of the return light RL when they are almost the same. Further, the color of the material of the finger sack 77 is also preferably transparent. However, as long as the light used for fingerprint reading is transmitted, there is no problem even if the finger sack 77 is colored.

Next, another embodiment of the finger sack which is different from the finger sack 77 shown in FIG. 2 will be described. 5 to 7 show another embodiment of the finger cot according to the present invention, which can be applied to the fingerprint reading surface 44 of the fingerprint reading device 10 shown in FIG. As shown in FIGS.
7 includes a cylindrical replacement part 180 and a main body 190, for example.
have. The replacement part 180 can be made of natural rubber or silicone rubber having elasticity, flexibility and adhesion as described above, or various kinds of polymer films, and is preferably cylindrical.

On the other hand, the main body 190 can be made of the same material as the replacement part 180, but has a finger insertion section 191 and an information recording section 192. Information recording unit 1
The information related to fingerprint reading, such as information about an individual to be used, can be recorded in the format 92, for example, in the form of a barcode. However, the information recording unit 19
2 can of course be recorded not only in a format such as a barcode but also in another encryption format. The main body 190 is moved by the arrow R with a finger.
By pushing in the direction and contracting, it can be inserted into the replacement part 180. The inserted state is shown in FIGS. As shown in FIG. 5, the finger F can be inserted into the insertion section 191 and the information recording section 192 can be placed facing the fingerprint reading surface 44 side. Thereby, the finger F
It is of course possible to simultaneously read the personal information and the like recorded in the information recording section 192 while reading the pattern of the fingerprint 20 of.

If the replacement part 180 shown in FIGS. 6 and 7 is damaged or soiled, the replacement part 180 is removed from the main body 190, so that a new replacement part 18 is obtained.
Can be exchanged for 0. In this way, fingerprint collation can be performed using a new replacement part 180. For example, every time a fingerprint is read, the replacement part 180 made of a thin film is replaced, so that the matching ability of fingerprint matching can be improved. Even if another person other than the person using the finger sack 177 shares the finger sack 177, in order to avoid direct or indirect contact with the other person, the replacement part 180 must be attached to the main body each time. It can be removed from 190 and replaced with a new replacement part 180. In this way, even if an unspecified number of users use the fingerprint reader, each individual can perform fingerprint reading using the new replacement part 180 only by replacing the replacement part 180. It can be performed reliably and the feeling of cleanliness can be improved.

In the embodiment of the present invention, the light of the light source is totally reflected on the fingerprint reading surface of the prism, so that the return light RL includes the image information of the fingerprint pattern and the CCD camera shown in FIG. 38 can be guided using the optical lens 36. In this case, depending on the environment or the physical condition of the user, even if the moisture or lipid at the fingertip is insufficient,
Since the finger cot 177 plays the role, it is possible to prevent the fingerprint reading performance from being lowered. In particular, by using the finger cot exclusively for each individual, contact with an unspecified number of others can be avoided. That is, if the replacement part is replaced, physical contact with an unspecified large number can be avoided, so that the cleanliness of use in reading with the fingerprint reading device is improved.

In the embodiment of the present invention, the point light source is not limited to an incandescent lamp, but may be, for example, a laser light source or an LED.
Of course, it is also possible to use (light emitting diodes) or other types of monochromatic point light sources. Further, such a fingerprint reading device 10 is not limited to being applied to a lock device for a door of a building or an automobile, but may be applied to a lock device of a safe or another lock device for security. .

[0029]

As described above, according to the present invention,
The fingerprint reading performance can be stabilized and used for each individual.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a fingerprint reading apparatus to which a finger cot for fingerprint reading according to the present invention can be applied.

FIG. 2 is a diagram showing a preferred embodiment of the fingerprint collation device of FIG. 1 and a finger cot of the present invention.

FIG. 3 is a perspective view showing an example of a finger cot.

FIG. 4 is a diagram showing an example of a state in which a finger inserted into a finger cot and a fingerprint reader are in close contact with each other.

FIG. 5 is a diagram showing another embodiment of the finger cot for reading a fingerprint according to the present invention.

FIG. 6 is a perspective view showing a finger cot;

FIG. 7 is an exploded perspective view of a finger cot.

FIG. 8 is a diagram showing an example of use of a conventional fingerprint reader.

FIG. 9 is a diagram showing an example of use of a conventional fingerprint reader.

FIG. 10 is a diagram showing an example of use of a conventional fingerprint reader.

[Explanation of symbols]

10 ... fingerprint reader, 30 ... light source, 34 ...
Prism, 36: Optical lens, 38: CCD camera (imaging element), 44: Fingerprint reading surface, 77:
Finger sack for reading, 177 ... finger sack for reading, 180 ... replacement parts, 190 ... body, 19
2 Information recording unit

Claims (5)

[Claims] A fingerprint is optically read by irradiating light on a fingerprint reading surface of an optical member on which the fingerprint is placed, and receiving return light including image information of the fingerprint by total reflection on the fingerprint reading surface. Finger-sack for fingerprint reading applied in a fingerprint reading device for making a finger-suck, which is made of a material having a refractive index substantially the same as the refractive index of an optical member, and is attached to a finger to be fingerprint-collected. Finger sack for fingerprint reading. 2. The finger cot for fingerprint reading according to claim 1, wherein the finger cot is made of natural rubber. 3. The method according to claim 1, wherein the film is made of a polymer film.
A finger cot for reading fingerprints described in. 4. The finger cot for fingerprint reading according to claim 1, wherein information related to fingerprint reading is recorded. 5. The finger cot for fingerprint reading according to claim 1, wherein a portion that contacts the fingerprint is replaceable.