JP2953440B2 - Imprint fingerprint image input device and input method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingerprint matching device for identifying an individual using a fingerprint, which is a collection of sweat glands on the surface of a finger of a human body, and more particularly to inputting a fingerprint image up to the side of a finger into a computer or the like. The present invention relates to an imprinted fingerprint image input device and an input method thereof.

[0002]

2. Description of the Related Art Conventionally, when inputting an imprint fingerprint image used for fingerprint collation, attention is paid to the difference in reflectance due to the unevenness of the fingerprint, and the unevenness of the fingerprint is obtained as a grayscale image by receiving light reflected by the finger. In inputting an imprinted fingerprint image, most of the methods take in an image when a finger is rotated on a finger rest.

FIG. 7A is a diagram showing the configuration of a fingerprint image input device in a conventional typical fingerprint matching device. Referring to FIG. 7A, the fingerprint image input device includes a light projecting unit 71 using white light as a light source, and a white light incident from the light projecting unit 71 on a contact surface with a finger so as to satisfy a total reflection condition. It comprises a prism 72 that reflects light, and an image sensor 73 that receives light reflected from the prism 72 and obtains a fingerprint image.

That is, when a finger is not in contact with the prism 72, the white light incident from the light projecting unit 71 is totally reflected on the upper surface of the prism 72, and the image obtained by the image sensor 73 becomes a bright image over the entire surface. .

When inputting a fingerprint, the prism 72
Your finger against the top of the screen. At this time, in the convex part of the fingerprint,
Since the skin and the prism 72 are in contact with each other, the total reflection condition is not satisfied, and most of the white light from the light projecting unit 71 is absorbed by the skin, and a part of the white light is reflected by the contact surface. On the other hand, since the skin and the prism 72 are not in contact with each other in the fingerprint concave portion, the total reflection condition is satisfied, and the white light from the light projecting unit 71 is totally reflected by the contact surface and is incident on the image sensor 73. Will be. As a result, the concave portions of the fingerprint are bright and the convex portions are dark, and a fingerprint image with contrast is obtained.

[0006] When collecting a rotationally imprinted fingerprint including the side of the finger, the fingerprint image input from the image sensor 73 is
The image is divided into strip-shaped area images 74 in the long finger direction (see FIG. 7B), and the contact between the fingerprint and the strip-shaped area image 74 is determined by a plurality of predetermined positions in the strip-shaped area image 74 that are repeatedly sampled. This is detected by examining the density of pixels or pixels at random positions, and this strip-shaped area image 74 is sequentially collected, and when the collection of the end strip-shaped area image is completed, the entire strip-shaped area collected The images were synthesized and an imprint fingerprint image was input (for details, see, for example, Japanese Patent Application Laid-Open No. 2-171818).

[0007]

However, the above-described conventional imprint fingerprint image input device has the following problems.

(1) The first problem is that there may be a case where an imprint fingerprint image cannot be input.

The reason for this is that even if the image density value detected by the fingerprint placement detection pixel exceeds the threshold value by the fingerprint placement detection pixel within the strip placement image area, the detected fingerprint area detection image may be larger than the threshold value. It is not always possible to collect a strip-shaped area image other than the fingerprint placement detection pixels, and a strip-shaped area image including a portion where the finger is not in contact with the finger placement table may be collected. Because.

(2) The second problem is that the number of failures to capture a strip area image increases.

[0011] The reason is that whether or not to take in a strip-shaped area image is determined by whether or not the image density value detected by the fingerprint placement detection pixel in the strip-shaped image area exceeds a threshold value. This is because even when the image density value of the fingerprint image itself does not exceed the threshold value, the collection of the strip-shaped region image is interrupted, and the user tries to collect the image again.

Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for detecting a strip-shaped region image by using an image density value of the fingerprint image itself when a stamped fingerprint image is input. As a result of using the device, an imprint fingerprint image input device and a method for inputting the imprint fingerprint image, which can avoid the occurrence of a portion where the imprint fingerprint image cannot be input or fail to capture the strip area image, can be obtained. To provide.

[0013]

In order to achieve the above object, an imprint fingerprint image input device according to the present invention comprises a planar light source for irradiating a parallel polyhedron on a finger with a parallel light beam; A two-dimensional image sensor that receives reflected light from a contact surface of the transparent polyhedron and converts the reflected light intensity into an electric signal; Provided with a fiber bundle and a photodetector that irradiate the light beam provided, and save only the image of the strip-shaped region of the portion where the light beam from the fiber bundle is blocked by contact of the finger with the transparent polyhedron surface, It is characterized in that an imprint fingerprint image is synthesized from each strip-shaped area image.

[0014]

Embodiments of the present invention will be described below. In a preferred embodiment of the imprint fingerprint image input device according to the present invention, a planar light source (1 in FIG. 1) for irradiating a transparent polyhedron (2 in FIG. 1) on which a finger is placed with a parallel light beam, and a transparent polyhedron (1 in FIG. The two-dimensional image sensor (3 in FIG. 1) that directly receives the reflected light from the contact surface of the finger with the finger (2 in FIG. 1) and converts the reflected light intensity into an electric signal, and the transparent polyhedron (2 in FIG. 1). A linear fiber bundle (4 in FIG. 1) for irradiating a light beam and a light source incident on the fiber bundle (FIG. 1) are provided on a transparent polyhedron so as to detect a portion where the finger rotates and comes into contact by blocking the light beam. 1-6), a linear photodetector (5 in FIG. 1) installed on a transparent polyhedron for detecting the interruption of the light beam from the fiber bundle, and a strip-shaped region where the light beam from the fiber bundle is interrupted. Images are transferred from a two-dimensional image sensor (3 in Fig. 1) The save and converted into digital image density data, a control unit for forming an inked fingerprint image from strip image density data of the stored respective regions (7 in FIG. 1), the.

The parallel light beam emitted from the planar light source (1 in FIG. 1) is applied to the contact portion between the transparent polyhedron (2 in FIG. 1) and the finger, and the reflected light from the contact portion has an intensity of 2 It is converted into an electric signal by a three-dimensional image sensor (3 in FIG. 1).

The fact that the light beam emitted from the linear fiber bundle (4 in FIG. 1) set on the transparent polyhedron is cut off by the finger rotating on the transparent polyhedron (2 in FIG. 1) is confirmed. The contact is detected by the upper photodetector (5 in FIG. 1).

The strip area image of the detected contact area is recorded by the control unit (7 in FIG. 1), and the head position and the tail position of the strip area are recorded.

If the last position of the strip-shaped area where the finger is rotated to block the light beam coincides with the center between the previously recorded start position and the last position, the strip-shaped area image at that time is recorded.

After recording the strip-shaped area image of the contact portion for the entire fingerprint area including the side of the finger, the image is synthesized so as to leave the maximum value of each strip-shaped area image density value to form an imprinted fingerprint image.

Therefore, according to the embodiment of the present invention,
It is possible to prevent a strip-shaped region image from being collected when there is a region where the finger does not partially touch the transparent polyhedron,
The area where the imprinted fingerprint image cannot be input does not occur, and, as in the method of detecting the strip-shaped area image from the image shading value using the fingerprint placement detection pixels, the sampling of the strip-shaped area image is interrupted and re-sampled is the image of the fingerprint image itself. It is not influenced by the density value, and the strip-shaped area image can be reliably collected.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

FIG. 1 is a diagram for explaining the configuration of one embodiment of the present invention.

Referring to FIG. 1, one embodiment of the present invention is:
A planar light source 1 that irradiates a parallel light beam to a transparent polyhedron 2 on which a finger is placed, and a two-dimensional image that directly receives reflected light from a contact surface between the transparent polyhedron 2 and a finger and converts the reflected light intensity into an electric signal. The sensor 3 and the transparent polyhedron 2 are arranged so that a part of the finger that rotates and contacts the transparent polyhedron 2 is detected by blocking light.
A linear fiber bundle 4 for irradiating a light beam, a light source 6 incident on the fiber bundle 4, and a line-shaped fiber bundle 4 disposed on a transparent polyhedron 2 for detecting interruption of a light beam from the fiber bundle 4. The photodetector 5 converts the image of the strip-shaped area from which the light beam from the fiber bundle 4 is cut off by converting the electric signal from the two-dimensional image sensor 3 into digital image density data and saves it. And a control unit 7 for forming an imprint fingerprint image from the image density data.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described in detail.

FIG. 2 shows a fiber bundle 4 installed on a transparent polyhedron 2 and a photodetector 5 in one embodiment of the present invention.
FIG. 4 is a diagram for explaining the positional relationship of FIG. Referring to FIG. 2, on the surface of the transparent polyhedron 2 where a finger comes into contact, a linear fiber bundle 4 regularly collected and assembled is installed at one end of the transparent polyhedron 2 and irradiates parallel rays. . At the opposite end on the transparent polyhedron 2, a photodetector 5 in which detection elements are regularly arranged in a line is installed to detect a light beam emitted from the fiber bundle 4.

FIG. 3 is a diagram for explaining the relationship between the interception of the light beam emitted from the fiber bundle 4 on the transparent polyhedron 2 and the detection of the strip region 8 in one embodiment of the present invention. As shown in FIG. 3, when a finger is placed on the transparent polyhedron 2,
At the part where the finger and the transparent polyhedron 2 are in contact, the fiber bundle 4
The light from is blocked. In the portion where the light beam is blocked, the light beam does not reach the photodetector 5 and the strip-shaped region 8 (see FIG. 3B) where the finger is in contact with the transparent polyhedron 2 can be detected.

The parallel light beam emitted from the light source 1 to the transparent polyhedron 2 is reflected on the transparent polyhedron 2 with which the finger is in contact,
The light enters the two-dimensional image sensor 3 and is converted into an electric signal. The control unit 7 converts this electric signal into a digital signal and records it as image density value data. At this time, the image density value data of only the strip-shaped area 8 detected by the photodetector 5 is recorded.

FIG. 4 is an explanatory view showing the process of collecting the strip-shaped area images 81 to 83 from the side in the embodiment of the present invention. FIG. 5 is an explanatory diagram showing, from above, a process of collecting the strip-shaped region images 81 to 83 in the embodiment of the present invention.

Referring to FIG. 4 and FIG.
Captures and records the strip-shaped area 81 (see FIG. 5A), and then records the leading end position S1 and the tail end position E1 of the strip-shaped area. The finger rotates on the transparent polyhedron 2 to form a strip-shaped area 82.
When the leading end position S2 of FIG. 5B is located between the leading end position S1 and the tail end position 1, the controller 7 collects and records the strip-shaped area 82.

Subsequently, the leading end position S2 and the trailing end position E2 are recorded, and the leading end position S2 of the strip-shaped area 83 (see FIG. 5C) is recorded.
When the position 3 is between the tip positions S2 and E2, the control unit 7
Collects and records the strip-shaped area 83.

This process is executed until the finger is separated from the transparent polyhedron 2. The control unit 7 compares the recorded strip-shaped area images, and synthesizes a portion where the images overlap with each other so as to leave data with a larger image density value, thereby forming an imprint fingerprint image.

FIG. 6 is a flow chart for explaining the operation of the control unit 7 in one embodiment of the present invention. With reference to FIG. 6, the operation of the control unit 7 in one embodiment of the present invention will be described.

First, the control unit 7 detects from the photodetector 5 a position where the light beam from the fiber bundle 4 is cut off when the finger is placed on the transparent polyhedron 2, and from the position, the initial strip-shaped region image is obtained. , The initial start position and the end position of the strip area are recorded (step S61).

When the finger starts rotating on the transparent polyhedron 2, the control unit 7 determines that the start position of the strip-shaped area detected by the photodetector 5 is the start position and the end position of the previously recorded strip-shaped area. It is determined whether the position coincides with the middle point of the position. If the position does not match, the tip position of the strip-shaped region from the photodetector 5 is detected again (step S62).

When the start position of the strip-shaped area detected by the photodetector 5 coincides with the intermediate point between the start position and the tail position of the previously recorded strip-shaped area, the control unit 7 sets the strip-shaped area. After recording the image, the leading and trailing end positions of the strip region at that time are recorded (step S63).

The control unit 7 detects whether the light beam from the fiber bundle 4 is blocked by the finger placed on the transparent polyhedron 2 by the photodetector 5 (step S64). Returning to step S62, it is checked again whether the start position of the strip-shaped area matches the middle between the recorded start position and the end position, and if so, a strip-shaped area image is recorded, and the start position and the end position are determined. Record.

When the finger leaves the transparent polyhedron 2 and the light beam from the fiber bundle 4 is no longer blocked, the light detector 5
When the detection is performed, the control unit 7 compares the recorded strip-shaped area images and, for a portion where the images overlap, compares the strip-shaped area image density value data for each pixel. , And the respective strip-shaped area images are combined to form an imprint fingerprint image (step S65), and all the control operations are terminated.

When detecting the next strip-shaped area, in addition to comparing whether the detected head position coincides with the middle between the recorded head position and the tail position, it also determines whether the head position and the tail position are the same. You may compare whether it matches near the end position. When combining the strip-shaped area images, there is a method of calculating the average of the image density values to obtain a new image density value, in addition to comparing and recording the maximum value of the portion where the images overlap.

[0039]

As described above, according to the present invention, the following effects can be obtained.

(1) A first effect of the present invention is that it is possible to avoid the occurrence of a portion where the imprint fingerprint image is not input in the input of the imprint fingerprint image.

The reason for this is that, in the present invention, the light contact from the fiber bundle provided on the surface of the transparent polyhedron is detected by the photodetector at the contact portion with the finger on the transparent polyhedron, and the finger always contacts. This is because a strip-shaped area is detected.

(2) A second effect of the present invention is that it is possible to prevent a failure in taking in a strip-shaped area image in input of an impression fingerprint image.

The reason is that, in the present invention, the image density value of the fingerprint image itself is not used for the detection of the strip-shaped area image, and the light detector detects the light blocking from the fiber bundle provided on the transparent polyhedral surface. This is because a strip-shaped area image is detected and a strip-shaped area image can be detected even when the fingerprint image density value is small.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram for explaining one embodiment of the present invention;
It is explanatory drawing which shows the positional relationship of the fiber bundle on a transparent polyhedron, and a photodetector.

FIG. 3 is a diagram for explaining one embodiment of the present invention;
It is explanatory drawing showing the relationship between light-blocking from the fiber bundle on a transparent polyhedron, and detection of a strip-shaped area.

FIG. 4 is a diagram for explaining one embodiment of the present invention;
It is explanatory drawing which represented the collection process of the strip-shaped area image from the side.

FIG. 5 is a diagram for explaining one embodiment of the present invention;
It is explanatory drawing which represented the collection process of the strip-shaped area image from the top.

FIG. 6 is a flowchart illustrating an operation of the control unit when an impression fingerprint image is input according to the embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional fingerprint image input device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Transparent polyhedron 3 2D image sensor 4 Fiber bundle 5 Photodetector 6 Light source 7 Control part 8 Strip area 81 Strip area 82 Strip area 82 Strip area E1 Last position E2 Last position E3 Last position S1 Tip position S2 Tip position S3 Tip position

Claims (3)

(57) [Claims] 1. A planar light source for irradiating a transparent polyhedron on a finger with a parallel light beam, a two-dimensional light receiving light reflected from a contact surface between the transparent polyhedron and the finger and converting the reflected light intensity into an electric signal. An image sensor, and a fiber bundle and a light detector that irradiate light beams provided on both sides to detect a contact position of the finger on a surface of the transparent polyhedron that contacts the finger, and An imprint fingerprint image characterized by storing only an image of a strip area of a portion where light from the fiber bundle is blocked by contact with a transparent polyhedron surface, and synthesizing an imprint fingerprint image from each of the strip area images. apparatus. 2. A flat light source for irradiating a transparent polyhedron on a finger with a parallel light beam; 2. A light source for directly receiving reflected light from a contact surface between the transparent polyhedron and the finger and converting the reflected light intensity into an electric signal 2. A three-dimensional image sensor, a linear fiber bundle for irradiating a light beam, which is installed on the transparent polyhedron, for detecting a portion where a finger rotates and comes into contact with the transparent polyhedron by blocking the light beam, and the fiber bundle And a light source incident on the fiber bundle to detect the interruption of the light beam from the fiber bundle.
A line-shaped photodetector installed on the transparent polyhedron, and an image of a strip-shaped area in which light from the fiber bundle is blocked, converts an electric signal from the two-dimensional image sensor into digital image density data. And a control unit for storing and storing and forming an imprint fingerprint image from the strip image density data of each area. 3. A first method for detecting a contact area of a finger by contacting a finger with the transparent polyhedron and cutting off a light beam from a linear fiber bundle for irradiating a light beam provided on the transparent polyhedron. Step, the detected, reflected light intensity received from the contact surface of the finger and the transparent polyhedron is converted into an electrical signal by a two-dimensional image sensor, from the electrical signal strip image density data near the contact area, the A second step of recording by the control unit; a third step of recording the positions of the head and the tail where the light beam from the fiber bundle is blocked; and a finger rotating on the transparent polyhedron, the fiber When the rearmost position for blocking the light beam from the bundle coincides with the vicinity of the center between the previously recorded start position and the rearmost position, the contact between the finger and the transparent polyhedron blocks the light beam from the fiber bundle. A fourth step of detecting a surface, and from the second step, until a finger rotating on the transparent polyhedron detects that the light beam from the fiber bundle is no longer blocked by leaving the transparent polyhedron. A fifth step of repeating the fourth step, and combining the recorded strip image density data with the control unit,
A sixth step of forming an imprint fingerprint image; and a method of inputting an imprint fingerprint image.