JPS6159580A - Fingerprint picture input device - Google Patents

Abstract

PURPOSE:To judge a forged fingerprint input by measuring and storing the number of black picture elements of a picture pattern due to a reflecting light when a fingerprint is taken and the number of black picture elements after a prescribed time passes, comparing both measured values and detecting an increase in the number of black picture elements. CONSTITUTION:A fingerprint taken on a prism is optically scanned and a picture pattern obtained at an input part 1 converted to a quantizing signal is stored by a picture memory 4. On the other hand, an ID umber from a keyboard 2 accesses a file 9 in which characteristic information of a fingerprint pattern of respective persons is stored beforehand, and equivalent fingerprint characteristic information is read and supplyed to a collating part 5. Here, information from the file 9 and characteristic information extracted from a memory are compared and collated. On the other hand, a black picture element measuring part 6 respectively measures the number of black picture elements of a constant density or above detected at the time of scanning in prescribed two times before or after fine time passes, by a command of a control part 3. Respective measured values are stored in a black picture element number storing part 7, these both measured values are compared at a comparing part 8 and if the increase in the number of black picture elements is not detected, the fingerprint is judged to be forged fingerprint.

Description

TECHNICAL FIELD The present invention relates to a fingerprint image input device, and more particularly to an image input device that optically detects a fingerprint pattern and generates an electrical signal.

Conventional systems that use fingerprints to identify individuals have extremely high reliability due to the characteristics of fingerprints, which are ``unique for all people'' and ``unchangeable throughout life.'' Various devices have been proposed for verifying identity with fingerprints registered in a registered file.

In the fingerprint identification device, a finger placed on the finger device surface of a glass prism is detected by a light source and an imaging device such as an ITV by using optical boundary changes of the glass from the back side of this placement surface. It has a fingerprint input position B that generates a photoelectric conversion image of a fingerprint pattern, and is disclosed in, for example, Japanese Patent Laid-Open No. 54-69300 and Japanese Patent Laid-Open No. 54-85600.

In such devices, when a fake fingerprint is input, it is necessary to detect it, reject the input of the fake fingerprint, and prevent the verification process from being performed. Conventionally, there are no countermeasures to prevent such fake fingerprint input. is hardly considered. An example of such a form of inputting a fake fingerprint is to place a forgery made of rubber or the like, which is engraved in a precise imitation of a fingerprint pattern, on a transparent glass prism.

OBJECTS OF THE INVENTION An object of the present invention is to provide a fingerprint image input device that prevents unauthorized use by prohibiting input of forged patterns of fingerprint images as described above.

Structure of the Invention The fingerprint image input device according to the present invention is characterized in that a finger is placed on the placement surface of a transparent body, and light is irradiated onto the placement surface from the side opposite to the finger, and light is reflected from the placement surface. A fingerprint input device that detects a fingerprint image pattern using light, which measures the number of black pixels of an image pattern by reflected light at a predetermined time when a fingerprint is imprinted, and the number of black pixels after a predetermined time has elapsed from this predetermined time. and a means for comparing these two measured values to detect whether or not the number of black pixels has increased over time, and by detecting this increase, it is determined whether a fake fingerprint has been input. Features.

Example The present invention will be explained in detail below using the drawings.

When a fake fingerprint is entered using a rubber stamp like the one mentioned above, unlike a human finger, it does not produce any sweat.
The temporal change in image density obtained by this forged fingerprint does not occur. On the other hand, in the case of a human finger, the shading of the image changes over time due to sweating. This is because sweat due to perspiration fills up between the fingers and the prism surface over time, and the incident light from the light source is refracted by this sweat. The present invention utilizes this fact to prevent the input of forged fingerprints, and FIG. 1 shows a schematic block diagram of a fingerprint matching system using a fingerprint image input device according to an embodiment of the present invention.

An image pattern obtained by an input section 1 that optically scans a fingerprint imprinted on a prism surface and converts it into an m-signal is temporarily stored in an image memory 4.

On the other hand, the ID number from the keyboard 2 accesses the file 9, but this file 9 stores the characteristic information of each person's fingerprint pattern in advance, and the corresponding fingerprint characteristic information is read out by the number 10 and verified. 5. The collation unit 5 compares and verifies the information from the file 9 and the characteristic information extracted from the fingerprint image pattern stored in the memory.

On the other hand, a black pixel measuring section 6 is provided to detect changes in density of the input fingerprint image over time. The number of black pixels having a certain density or higher is measured. Each measurement value is stored in the black pixel number storage section 7, and these two measurement values are compared in the comparison section 8. Based on the comparison result, it is determined whether or not a forged fingerprint has been input.

Here, each component in the embodiment can be easily accomplished by a person skilled in the art, and the details thereof will be omitted. Furthermore, a known method is used as the verification method.

FIG. 2 is a flowchart for explaining the operation of the block in FIG. 1, and shows the flow of forgery input determination based on the presence or absence of a change in shading over time, that is, an increase in the number of black pixels.

When the ID number is input and a fingerprint is affixed, the image is scanned and the counting of the number of black pixels is started.

The measurement results at this time are stored and a fingerprint verification process is performed in parallel. After this, after a certain period of time has elapsed, the image is scanned again, and the number of black pixels is 51, which is memorized and the number of black pixels from the previous scan 11 is compared with the number of black pixels this time to determine whether or not it is a forged input. It will be done. If no increase in the number of black pixels is detected, it is determined that a forged fingerprint such as a rubber stamp has been input, and all subsequent verification processing is rejected.

If the number of black pixels increases, it is assumed that the input was made by a human finger, and the verification result is output.

11. According to the present invention, it is possible to effectively prevent the input of forged fingerprints, and it is expected that the reliability of the system will be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the blocks in FIG. Explanation of symbols of main parts 1... Input section 3... Control section 6... Black pixel measuring section 7... Black pixel number storage section 8... ...Black pixel number comparison section

Claims (1)

[Claims] Fingerprint image input in which a finger is placed on the placement surface of a transparent body, light is irradiated onto this placement surface from the side opposite to the finger, and a fingerprint image pattern is detected using reflected light from this placement surface. The apparatus comprises means for measuring and storing the number of black pixels of the image pattern caused by the reflected light at a predetermined time when a fingerprint is imprinted and the number of black pixels after a predetermined period of time has elapsed from the predetermined time; 2. A fingerprint image input device, comprising means for comparing and detecting whether or not the number of black pixels has increased over time, and determining whether a fake fingerprint has been input by detecting this increase.