JPS61255480A - Picture input device - Google Patents

Abstract

PURPOSE:To prevent illegal picture input by inhibiting a forgery finger print pattern input using an external light source. CONSTITUTION:When a user pushes a finger on a transparent finger placing face of finger print input section 17, the finger print input section 17 applies photoelectric conversion to a picture, uses a forgery input discriminating section 18 to detect the presence of fluctuation on the same position of a contrast pattern, and when the fluctuation is detected, the pattern information is stored in a picture memory 19. An ID number is inputted from a keyboard to a collation processor, the corresponding finger characteristic information is called from a file 20, the characteristic is compared with that of the pattern in the picture memory for collation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image input device, and more particularly to an image input device that optically detects a pattern to be verified, such as a fingerprint, and generates an electrical signal.

(Problems with conventional technology and sheep) In systems that identify individuals using fingerprints, pattern recognition technology Various devices have been proposed that use the method to check the identity of a collected fingerprint and a previously registered fingerprint.

In such a fingerprint verification device, a finger placed on a transparent body, for example, a glass mounting surface, is connected to a light source and an ITV (
It has a fingerprint input device that generates a charge-transformed image of a fingerprint pattern using an imaging device such as an industrial television (Industrial Television), etc.; −
It is disclosed in the s560o publication.

FIG. 4 is a block diagram showing a fingerprint input device disclosed in Japanese Unexamined Patent Publication No. 54-69300.

This fingerprint input device includes a reflective polarization detection section 1 and an internal light source 2.
, polarizing filters 3 and 4, plate glass 5 attached to reflective polarization detection section 1, and imaging device l! 6, the light ray 7 emitted from the internal light source 2 passes through the polarizing filter 3 and becomes a polarized light 8, and the polarized light 8 is irradiated onto the plate glass 5. Reflected light ray 1 that was reflected and passed through the polarizing filter 4
0 is received by the imaging camera 6 and converted into an electrical signal.

FIG. 5 is a block diagram showing a fingerprint input device disclosed in Japanese Unexamined Patent Publication No. 54-85600.

This fingerprint input device is obtained by replacing the plate glass 5 of the fingerprint input device shown in FIG. 4 with Burisma 11, and therefore the same elements as those in FIG. 4 are given the same numbers.

In such a fingerprint input device, the user presses his or her finger against the top surface (placement surface) of the transparent body of the glass plate 5 or the prism 11 when stamping the fingerprint.

On the surface of the finger, a fingerprint pattern is formed by the unevenness of the skin.
Since the unevenness is covered with a trace amount of moisture layer such as sweat, the reflectance of the plate glass or prism is different between the convex part and the concave part. That is, there is an air layer in the concave portion, and the situation is the same as when no finger is placed on the concave portion, and the polarized light ray 8 is reflected as a reflected light ray 9 that does not cause any disturbance in the polarization. In the convex portion, the reflectance decreases on the mounting surface, and
Although the light rays incident on the water layer are also reflected on the surface of the finger, the reflected light rays 9 have a small amount of light with disordered polarization due to disturbance of polarization due to diffuse reflection and interference caused by the thinness of the water layer. Then, using a polarizing filter 4 whose polarization axis is aligned with the reflected light beam 9 in which the polarization is undisturbed, the reflected light beam 10 makes the concave parts of the finger surface bright and the convex parts dark.
obtained as. This reflected light beam 10 is converted into a photoelectrically converted image of a fingerprint pattern by an imaging device t6.

In such a fingerprint input device, a fingerprint image is placed on a surface as shown in FIG. 6 without actually imprinting the fingerprint, and a transparent image is transmitted from a separately prepared external light source 13 through a separately prepared prism 14. A possible forgery input method is to irradiate the thin film 12 with light and input a forged fingerprint image to the imaging device 16 inside the device. In this case, there is no air space between the transparent thin film 12 and the fingerprint placement prism 11, and between the fake fingerprint input prism 14 and the transparent thin film 12, and if they are not brought into close contact with each other, the external fake fingerprint input will not be possible. Since no image is generated by the light source 13, in order to eliminate these air layers, maintain uniform adhesion between both prisms and the transparent thin film, and ensure accurate image detection, a liquid such as water is applied between them to moisten them in advance. Then enter a fake fingerprint.

If such a forged fingerprint is input in the fingerprint input device, a problem arises in that the image input device including the fingerprint input device is used illegally.

(Object of the Invention) An object of the present invention is to provide an image input device that prohibits the input of forged fingerprint patterns using an external light source and prevents unauthorized use.

(Structure of the Invention) The present invention is directed to placing an object to be inspected having a pattern to be verified on a mounting surface of a transparent body #tlfL, and performing the above-mentioned process from the opposite side of the object to be inspected through the transparent body. In an image input device that detects the pattern to be matched using an image obtained by reflected light due to an optical boundary change occurring on the mounting surface when the mounting surface is irradiated with light from an internal light source, a detecting means for detecting a gray level value of a pixel at a predetermined position; a means for binarizing an image by comparing a predetermined threshold value given in advance with the detected gray value; and a means for binarizing an image; means for storing the position and its gray value, a time after storing the black pixel position and gray value, and on an image captured within a certain period of time after this time;
comprising a determining means for detecting the gray scale value of the stored black pixel position and comparing it with the stored gray scale value of the pixel at a predetermined position, and then determining whether there is a change in the gray scale value at the same position;
The present invention is characterized in that input of a forged pattern to be verified is prevented based on the determination result by the determination means.

(Example) Below, the present invention will be described in detail using the drawings. As mentioned above, when a fake fingerprint is entered using a rubber stamp, etc., unlike a human finger, there is no sweating effect, so there is no change over time in the shading values on the image obtained from this fake fingerprint. . On the other hand, when printing with a human finger, the shading value changes on the image due to sweat generated by perspiration. This is because sweat due to perspiration fills up between the fingers and the prism 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.

FIG. 1 is a schematic diagram of a fingerprint input unit used in the image input device of the present invention. This fingerprint input section is the same as the fingerprint input device shown in FIG. 5, except that the polarizing filters 3 and 4 are removed. The rest of the structure is similar to the fingerprint input device of FIG. 5, so the same elements as those of FIG. 5 are given the same numbers.

In the fingerprint input section having such a structure, the light beam emitted from the internal light source 2 is reflected by the mounting surface of the prism 11. The reflected light enters the imaging device 6, for example. The imaging device 6 obtains a fingerprint image using reflected light from the mounting surface of the prism 11.

In such a fingerprint input section, when attempting to input a fake fingerprint using a fingerprint image transferred to an OHP plastic film or a rubber stamp that precisely imitates a fingerprint using silicone rubber, black pixels on the image may disappear due to sweating if the finger is used. There is a temporal change in the upper gradation value, and the density becomes higher. However, since a fake fingerprint made of plastic or rubber does not cause sweating, the shading values in the image do not change over time. Therefore, we compare the shading value of a predetermined black pixel on the image captured at a certain predetermined time during stamping with the gradation value of the same black pixel on the same image captured a short time after that time, and we calculate the change in the gradation value. By detecting it, it becomes possible to determine whether or not the input is a forged fingerprint.

It should be noted that the detection of the gray scale values of pixels in the detected image can be easily accomplished, and the detailed description thereof will be omitted here.

FIG. 2 shows a schematic block diagram of an embodiment of the image input device of the present invention. This image input device includes the fingerprint input unit 17 shown in FIG. a forged input determination unit 18 that compares the input value with the input value and determines whether the input is forged based on the result; an image memory 19 that stores fingerprint pattern information obtained by photoelectrically converting the fingerprint pattern image in the fingerprint input unit 17; a registration file 20 in which fingerprint characteristic information of each user is stored in advance;
Personal same root number to access this registration file (
The device includes a keyboard 21 for inputting an ID number), and a verification processor 22 for comparing the characteristics of the fingerprint characteristic information retrieved from the file 20 and the fingerprint pattern information stored in the image memory 19.

In the image input device having such a configuration, when the user presses his or her finger on the transparent placement surface of the fingerprint input unit 17 to imprint a fingerprint, the fingerprint input unit g is activated as described in FIGS. 4 and 5. The fingerprint pattern image is photoelectrically converted, and the obtained fingerprint pattern information is stored in the image memory 19 via the forgery input determination section 18.

On the other hand, enter your personal ID number (ID number) on the keyboard 21.
When the ID number is input to the verification processor 22, the verification processor 22 creates the registration file 2 according to the input ID number.
0'tl-access and select and call up fingerprint characteristic information corresponding to the ID number from the fingerprint characteristic information of each user stored in advance in the file 20. The verification processor 22 performs feature comparison between the fingerprint feature information read from the FI/L/20 and the fingerprint feature pattern stored in the image memory 19 to verify identity.

In such fingerprint identity verification, the image input device of this embodiment performs the following operations in order to prohibit the input of forged fingerprint patterns and prevent unauthorized use as described above.

#￥3 Figure shows a 70-chart of this operation. When the user presses his or her fingerprint on the fingerprint input device 17, the detector 6
A fingerprint image is obtained and binarized by detecting the density values of all pixels and comparing them with a pre-given threshold value. is sent to the forgery input determination unit and stored.
(81).

After a predetermined period of time has elapsed, the image is captured again and the grayscale values at the pre-memorized positions are detected + (
82). The forgery manual judgment unit 18 compares the pre-stored gradation value with the newly detected gradation value at the same position, and determines whether or not a density change has occurred within a certain period of time (83). 0 If the newly detected gray value matches the pre-stored gray value or has a small change, it is determined that there is a suspicion that a fake fingerprint was input using plastic film, rubber, etc. that does not change the density due to sweating, and Request the user to affix their fingerprint again.

t-(84). Note that here, as a means for requesting the user to re-stampe, visual or auditory means can be used.

It is determined whether such a fingerprint re-request has been repeated a predetermined number of times (85), and if it is within the predetermined number of times, the process of steps 5l-s4 is repeated again and the fingerprint re-request is repeated a predetermined number of times. If the temporal change in the gray value of the black pixel is still not confirmed even after repeated attempts, all subsequent verification processing will be rejected as a suspicion of forged input.
(86).

In the process in s3, if the gray value of the black pixel newly detected by the detector 6 does not match the gray value stored in advance, it is assumed that there is no suspicion of forged fingerprint input and that the input is normal, and the subsequent verification is performed. Execute the process (
(87). In this way, according to this embodiment, it is possible to prohibit the input of a forged fingerprint pattern using an OHP plastic film or the like.

It is clear that the present invention can be applied not only to fingerprint verification devices, but also to the prevention of input of forged verification patterns of plastics, rubber, etc., in identity verification devices for general objects to be tested that have verification patterns. It is.

(Effects of the Invention) According to the present invention, Bata, Ntl! In a device that detects a pattern to be matched using the m-technology, it is possible to effectively prevent input of a forged pattern to be matched, thereby improving the reliability of the system.

[Brief explanation of drawings]

FIG. 1 shows a schematic configuration of a fingerprint input section. FIG. 12 is a schematic block diagram showing an embodiment of the present invention. FIG. 3 is a diagram 70- for explaining the operation of the embodiment shown in #2.
Diagram showing a chart. FIG. 4 and FIG. 5 are diagrams showing a fingerprint input device. FIG. 6 is a diagram for explaining a method of inputting a forged fingerprint. 2... Internal light source 5... Plate glass 6... Imaging device 11.14... Prism 13... External light source 17... Fingerprint input unit 18 ...Forgery input determination unit 19...Image memory addition...Registration file 21...Keyboard

Claims (1)

[Claims] An object to be inspected having a pattern to be compared is placed on a placement surface of a transparent body, and light from an internal light source is directed from the opposite side of the object to the placement surface through the transparent body. In an image input device that detects the to-be-matched pattern using an image obtained by reflected light due to an optical boundary change occurring on the placement surface when irradiated, the grayscale value of a pixel at a predetermined position in the image a means for binarizing the image by comparing the detected gradation value with a predetermined threshold given in advance; and a means for binarizing the image, and storing the position of the black pixel in the image and its gradation value. means for detecting the gray value of the stored black pixel position on the time after the black pixel position and the gray value are stored, and an image captured within a certain period of time after this time; A determining means is provided for determining whether or not there has been a change in the gray value at the same position after comparing it with the gray value of a pixel at the position, and based on the determination result by the determining means, input of a forged pattern image to be verified is prevented. An image input device characterized in that: