JP3120272B2 - Fingerprint input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fingerprint input device for registering a fingerprint or inputting a fingerprint image for collation with a fingerprint image already registered.

[0002]

2. Description of the Related Art Since fingerprints have the characteristics of "everyone is unidentified" and "lifelong invariant", a fingerprint collation system is also used as a personal collation system particularly in a field where high security is required. In this fingerprint collation system, a device for inputting a fingerprint image is an essential component. This fingerprint input device is composed of an optical system. By the way, the quality of the collation accuracy of the fingerprint collation system largely depends on whether or not a fingerprint image can be input correctly. Therefore, a fingerprint input device for dealing with distortion and blurring of a fingerprint image is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-142675.
Gazette, Japanese Utility Model Laid-Open Publication No. 63-99960,
Some proposals have already been made, such as Japanese Patent No. 76984.

[0003]

However, in these conventional fingerprint input devices, distortion and blurring of the fingerprint image cannot be simultaneously solved because a lens is used for the optical system. FIG. 16 shows a main part of an optical system of a conventional fingerprint input device. In the figure, 1 is a prism, 2 is a lens, AB is a fingerprint collecting surface of the prism 1, O is a lens 2
Is the focal point of the lens 2. In this figure, it is assumed that the refractive index of the prism 1 is equal to that of air for easy understanding. Although not shown in this figure, an incandescent lamp is provided on the lower surface side of the prism 1 and light from the incandescent lamp is applied to the fingerprint collecting surface AB through the inside of the prism 1.

In this optical system, in order to prevent the image of the pattern surface of the finger placed directly or indirectly on the fingerprint collecting surface AB, that is, the fingerprint image from being blurred, the image forming surface of the light receiving device must be E-shaped. What is necessary is just to put on G (imaging plane). However, in this case, since the optical path ratio is not constant, (AO: OG ≠ BO: O
E), the fingerprint image is distorted. On the other hand, in order to prevent the fingerprint image from being distorted, the image plane of the light receiver may be placed on the EH (image plane). However, in this case, the fingerprint collection surface A-
The point A of B spreads on HK on the image plane EH, and the fingerprint image is blurred. As described above, since the lens 2 is used, blurring and distortion cannot be eliminated at the same time.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fingerprint input device capable of greatly reducing blur and distortion.

[0006]

In order to achieve the above object, a first invention (an invention according to claim 1) includes a prism having one direction surface as a fingerprint collecting surface, A light source for irradiating the fingerprint collecting surface with light through the interior thereof, and a light source which is incident on the prism from the light source, is provided on a passage of light reflected by a finger pattern placed on the fingerprint collecting surface and emitted from the prism. An optical fingerprint collecting surface that is equivalent to the fingerprint collecting surface when the prism is replaced with air, provided with a pinhole and an imaging surface on which the light emitted from the prism passing through the pinhole forms an image. And the imaging plane are substantially parallel. According to the present invention, the light emitted from the prism reflected by the pattern of the finger placed directly or indirectly on the fingerprint collecting surface passes through the pinhole and is substantially parallel to the optical fingerprint collecting surface of the prism. The image is formed on the image forming plane.

[0007] The second invention (the invention according to claim 2) is the first invention.
In the present invention, when the optical fingerprint collecting surface has a distortion with respect to the fingerprint collecting surface, the imaging surface is rotated by a required angle. According to the present invention, it is possible to reduce the distortion generated on the optical fingerprint collecting surface by rotating the imaging surface which is substantially parallel to the optical fingerprint collecting surface of the prism by a required angle. .

According to a third invention (an invention according to claim 3), the first prism arranged with its one-way surface as a fingerprint collecting surface, and the fingerprint collecting surface is irradiated with light through the inside of the first prism. And a pinhole provided in a passage for light emitted from the first prism after being reflected by a finger pattern surface which is incident on the first prism from the light source and placed on the fingerprint collecting surface and is emitted from the first prism. An imaging surface on which the light emitted from the first prism passing through the pinhole is imaged, and a second prism placed in front of the imaging surface, the fingerprint of the first prism being provided. The collection surface and the imaging surface are substantially parallel, the fingerprint collection surface of the first prism and the surface on the imaging surface side of the second prism are substantially parallel, and the light is emitted to the pinhole of the first prism. The plane and the plane of incidence from the pinhole of the second prism are almost flat. It is obtained by the. According to the present invention, the optical system on the first prism side and the optical system on the second prism side are made similar to each other with the pinhole as the center, and the finger pattern surface directly or indirectly placed on the fingerprint collection surface is formed. The reflected light from the first prism passes through the pinhole, passes through the second prism, and is imaged on the image plane.

According to a fourth aspect of the present invention, in the first, second and third aspects, a pinhole position adjusting means for adjusting the position of the pinhole is provided. According to the present invention, the position and size of the fingerprint image on the imaging surface can be changed by adjusting the position of the pinhole in the front-back, left-right, up-down directions, and the like. Fifth invention (the invention according to claim 5)
According to a fourth aspect of the present invention, in the fourth aspect, the pinhole position adjusting means is constituted by a manual adjusting mechanism, and further provided with a display unit for displaying a fingerprint image formed on the image forming surface. According to the present invention, the position and size of the fingerprint image on the imaging surface can be changed by adjusting the position of the pinhole in the front-rear, left-right, up-down directions, etc. while viewing the displayed fingerprint image. .

The sixth invention (the invention according to claim 6) is the fourth invention.
In the invention, the pinhole position is automatically adjusted by the pinhole position adjusting means. According to the present invention, the position of the pinhole is automatically adjusted, and the position and size of the fingerprint image on the imaging surface are adjusted to the setting. In a seventh invention (an invention according to claim 7), in the first, second, and third inventions, the light source is an LED or a laser beam irradiator. According to the present invention, the light of the LED or the laser beam irradiator, that is, the light of a single wavelength is irradiated on the fingerprint collecting surface through the inside of the prism.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. [Basic Principle] FIG. 1A is a diagram showing a main part of an optical system of a fingerprint input device according to the present invention. In the figure, AB is a fingerprint collecting surface of the prism 1, C'-D 'is a pinhole plate surface having a pinhole PH formed in the center thereof, and O is a center of the pinhole PH. In this figure, it is assumed that the refractive index of the prism 1 is equal to that of air for easy understanding. Also not shown in this figure,
An LED is provided on the lower surface side of the prism 1, and light from this LED passes through the inside of the prism 1 and its fingerprint collecting surface A-
B is irradiated. Note that this LED may be a laser beam irradiator. Since the light emitted from the LED or the laser irradiator has a single wavelength and has less light unevenness with respect to an incandescent lamp, it is excellent in that the resolution is good, the life is long, and the influence of heat generation on the device is small.

In this optical system, the light emitted from the prism 1 reflected by the finger pattern placed directly or indirectly on the fingerprint collecting surface AB passes through the pinhole PH,
An image is formed on the image forming plane IJ. In this case, if the fingerprint collection plane AB and the imaging plane IJ of the prism 1 are parallel, the optical path ratio becomes constant (AO: OJ = BO: OI), and the fingerprint image is not distorted. Further, since one point on the fingerprint sampling plane AB is formed on one point on the imaging plane IJ, no blur occurs in the fingerprint image. Thereby, blur and distortion can be eliminated at the same time.

In FIG. 1A, it is assumed that the refractive index of the prism 1 is equal to that of air. However, actually, the refractive index of the prism 1 is different from the refractive index of air. Therefore, FIG.
As shown in (b), when the prism 1 is replaced with air, a surface equivalent to the fingerprint collecting surface AB is replaced with an optical fingerprint collecting surface A'-B '(curved surface A'-B shown by a broken line in the drawing). B ')
The optical fingerprint collection plane A′-B ′ and the image plane IJ
And are parallel. In this case, since it is difficult to make the imaging plane IJ a curved surface technically and costly, the straight line A'-
Let B 'be parallel to the imaging plane IJ. In other words, Δ
A'OB 'and ΔJOI are made similar. Thus, the optical path ratio becomes constant (A'O: OJ = B'O:
OI) and distortion of the fingerprint image can be suppressed. In addition, since one point on the straight line A′-B ′ is formed at one point on the image plane IJ, blurring occurring in the fingerprint image can be suppressed. Thereby, blurring and distortion can be significantly reduced.

The position and size of the fingerprint image on the image plane IJ can be adjusted by adjusting the position of the pinhole PH in the forward and backward directions (Z direction), left and right directions (X direction), and vertical direction (Y direction). Can be adjusted. Also, by adopting this method, compared to the method using a lens, the tolerance for assembling parts is large, and the cost, weight, and size can be reduced.

FIG. 2 is a block diagram of a fingerprint collating system using a fingerprint input device according to the present invention. In the figure, reference numeral 10 denotes a fingerprint input device, reference numeral 20 denotes a processing unit, and the fingerprint input device 10 includes a numeric keypad 10-1, a display (LCD) 10-2, and a fingerprint input unit 10-.
3 are provided. The processing unit 20 includes a control unit 20-1 having a CPU, a ROM 20-2, and a RAM 20-
3, a hard disk (HD) 20-4, a frame memory (FM) 20-5, and an external connection unit (I / F) 20-
6 and a Fourier transform unit (FFT) 20-7. The ROM 20-2 stores a registration program and a collation program.

In the fingerprint input device 10, the fingerprint input unit 10-3 includes a light source (LED) 10-31, a diffusion plate 10-32, and a prism 1 as shown in an enlarged view in FIG.
0-33, a pinhole plate 10-34, a pinhole position adjusting mechanism 10-35, and a light receiver 10-36.

In this example, the fingerprint input section 10-3 employs a total reflection method, and the LED 10-31 is connected to the prism 10-.
It is arranged on the lower left side of the lower surface 33, and the light from the LED 10-31 is irradiated to the fingerprint collecting surface AB through the inside of the prism 10-33. In this configuration, when the prism 10-33 is replaced with air, a surface equivalent to the fingerprint collecting surface AB is replaced with an optical fingerprint collecting surface A′-B ′ (curved surface A′-B shown by a broken line in the drawing). B ′), the optical fingerprint collection surface A′-B ′ and the light receiver 10-3.
6 is substantially parallel to the image plane IJ, that is, a straight line A'-
It goes without saying that B 'and the image plane IJ are parallel.

When the optical path separation method is adopted for the fingerprint input unit 10-3, as shown in FIG.
1 is disposed on the right side of the lower surface side of the prism 10-33, and the left side surface of the prism 10-33 is coated with black paint (or a light shielding plate) 10-37 so that light from the LED 10-31 is supplied to the inside of the prism 10-33. Through the fingerprint collection plane AB
Irradiation. Also in this case, when the prism 10-33 is replaced with air, the fingerprint collection surface A
-B 'is the optical fingerprinting surface A'-B'
(The curved surface A′-B ′ shown by a broken line in the figure), and the optical fingerprint collection surface A′-B ′ and the image forming surface I− in the light receiver 10-36.
J is almost parallel, that is, a straight line A′-B ′ and an image plane I−
Needless to say, J is parallel. The left side of the prism 10-33 is painted black (or a light shielding plate) 1
By applying 0-37, the influence of disturbance light incident from the outside can be prevented.

Regarding the principle of the total reflection method and the optical path separation method,
Reference 1 (Transactions of the Institute of Electronics and Communication Engineers '85 / 3 Vol. J6
8-D No. 3 pages 414 to 415), and a detailed description is omitted here. In the total reflection method,
It is assumed that total reflection occurs at the non-contact portion of the fingerprint and no total reflection occurs at the contact portion, and a difference between light from the non-contact portion and light from the contact portion is detected. In the optical path separation method, only light from a contact portion is detected without any light from a non-contact portion of the fingerprint. For reference, FIGS. 3B and 4
(B) illustrates a conventional configuration of a fingerprint input unit employing a total reflection method and an optical path separation method. Conventionally, an incandescent lamp 10-31 'is used as a light source,
The lens Ln is used for 0-36 '.

FIGS. 5A and 5B show the fingerprint input device 1.
0 is an external view and a plan view. This fingerprint input device 10
In the above, the fingerprint collection surface AB of the prism 10-33, that is, the upper surface UP of the prism 10-33 is exposed, and the operator's finger directly or indirectly (when a film is provided) on the upper surface UP of the prism 10-33. The guide 10-41 is formed in the case 10-4 so that the guide 10-41 may be placed on the case 10-4. The numeric keypad 10-1 and the display 10-2 are arranged side by side, and the numeric keypad 10-1 is provided with a fingerprint input confirmation key 10-11. Case 10-
On the side of 4, there are provided three-axis position adjusting knobs Cx, Cy and Cz which are rotationally connected to the pinhole position adjusting mechanism 10-35.

[Registration of Fingerprint (Manual Adjustment of Pinhole Position)] In this fingerprint collation system, a user's fingerprint is registered as follows. That is, before operation, the user inputs the ID number assigned to the user using the numeric keypad 10-1 (step 70 shown in FIG. 7).
1) Put a finger on the upper surface UP (fingerprint collecting surface AB) of the prism 10-3 along the guide 10-41 of the fingerprint input device 10. LED on the fingerprint collecting surface AB of the prism 10-3
The light from 10-31 was irradiated, and the fingerprint collection surface A-
In the fingerprint concave portion (valley line portion) that does not contact B, the LED 10
Light from -31 is totally reflected. Conversely, fingerprint collection surface AB
At the convex portion (ridge portion) of the fingerprint contacting with the LED, the total reflection condition is broken, and light from the LEDs 10-31 is scattered.

The outgoing light from the prism 10-33 reflected by the finger pattern placed on the fingerprint collecting surface AB passes through the pinhole PH, and forms the image plane I- of the light receiver 10-36.
An image is formed on J. As a result, a fingerprint image with contrast is obtained, in which the valleys of the fingerprint are bright and the ridges are dark. The pattern of the collected fingerprint (registered fingerprint) is provided to the processing unit 20 as grayscale image data.

The control unit 20-1 operates the fingerprint input device 10
The image data of the registered fingerprint from the frame memory 20-5.
(Step 702) via the display 1
It is displayed on 0-2 (step 703). FIG. 6A shows a display example of the registered fingerprint at this time. This display 1
The user determines whether to change the position of the pinhole PH by looking at the fingerprint image displayed on 0-2.

That is, when the user views the fingerprint image displayed on the display 10-2 and the position of the fingerprint image is shifted, large or small, it is necessary to change the position of the pinhole PH. Judge. And
By adjusting the rotation angle positions of the three-axis position adjustment knobs Cx, Cy, and Cz, and adjusting the positions of the pinhole plate 3-34 in the X, Y, and Z directions via the pinhole position adjustment mechanism 10-35, That is, by adjusting the position of the pinhole PH in the X, Y, and Z directions, the position and size of the fingerprint image on the display 10-2 are set as required (steps 702 to 704).

After adjusting the position and size of the fingerprint image on the display 10-2 in this manner, the user presses the fingerprint input confirmation key 10-11. This allows
The control unit 20-1 determines that the capture of the registered fingerprint has been determined (step 705), and file the image data of the determined registered fingerprint in the hard disk 20-4 in association with the ID number (step 705). Step 706).

[Fingerprint Collation (Pinhole Position Manual Adjustment)] In this fingerprint collation system, collation of a user's fingerprint is performed as follows. During operation, the user inputs the ID number assigned to the user using the numeric keypad 10-1 (step 801 shown in FIG. 8), and moves the prism 10-3 along the guide 10-41 of the fingerprint input device 10.
A finger is placed on the upper surface UP (fingerprint collection surface AB) of the. As a result, the pattern of the collected fingerprint (collation fingerprint) is converted into grayscale image data by the
Given to.

When the ID number is given via the numeric keypad 10-1, the control unit 20-1 operates the hard disk 20-
The registered fingerprint image data corresponding to the ID number is read from the registered fingerprint filed in Step 4 (Step 802), and displayed on the display 10-2 (Step 803).

Further, the control unit 20-1 operates the fingerprint input device 1
The image data of the verification fingerprint from 0 is stored in the frame memory 20-
5 (step 804), and superimposed on the fingerprint image of the registered fingerprint on the display 10-2 (step 805). FIG. 6B shows a display example at this time.
The user determines whether or not to change the position of the pinhole PH by observing the overlapping state of the fingerprint image of the registered fingerprint and the fingerprint image of the collation fingerprint displayed on the display 10-2.

That is, looking at the fingerprint image of the collation fingerprint displayed on the display 10-2, the position of the fingerprint image is shifted or large with respect to the fingerprint image of the registered fingerprint.
If it is smaller, it is determined that the position of the pinhole PH needs to be changed. And three-axis position adjustment knob C
The rotation angle positions of x, Cy and Cz are adjusted, and the pinhole plate 3-34 is adjusted via the pinhole position adjustment mechanism 10-35.
By adjusting the position of the pinhole PH in the X, Y, and Z directions, that is, by adjusting the position of the pinhole PH in the X, Y, and Z directions, the position and size of the fingerprint image of the verification fingerprint on the display 10-2 are adjusted. To the fingerprint image of the registered fingerprint (steps 804 to 806).

After adjusting the position and size of the fingerprint image of the collation fingerprint on the display 10-2 in this way, the user presses the fingerprint input confirmation key 10-11. As a result, the control unit 20-1 determines that the acquisition of the collation fingerprint is determined (step 807), and compares the determined fingerprint image of the collation fingerprint with the fingerprint image of the previously read registered fingerprint. (Step 808), and the collation result is displayed on the display 10-2 (Step 80).
9).

In this embodiment, blur and distortion can be greatly reduced in accordance with the basic principle described above.
Pinhole P with axis position adjustment knobs Cx, Cy, Cz
By manually adjusting the position of H, the position and size of the input fingerprint image at the time of registration can be made required, and the positional deviation of the input fingerprint image at the time of registration and verification can be absorbed. In addition, it is possible to cope with the difference in size.

When the fingerprint image to be collected is small, the area of the background becomes large, and the matching accuracy is lowered. In this case, by moving the pinhole PH in the Z direction (in a direction away from the imaging plane IJ), the fingerprint image to be collected can be enlarged, and deterioration of the matching accuracy can be prevented. Further, the position adjustment at the time of shipment can be performed without dismantling the apparatus main body, and the position adjustment work at the time of shipment can be simplified.

In the above-described embodiment, the position of the pinhole PH is manually adjusted by the three-axis position adjustment knobs Cx, Cy and Cz at the time of registration and collation, but the position is automatically adjusted. It may be configured. FIG.
FIG. 10 and FIG. 10 show processing operations at the time of registration and verification at the time of automatically adjusting the position of the pinhole PH.

[Registration of Fingerprint (Automatic Adjustment of Pinhole Position)] In this case, the user inputs the ID number assigned to himself / herself using the numeric keypad 10-1 (step 901 shown in FIG. 9) and enters the fingerprint. Guide 10 of device 10-
A finger is placed on the upper surface UP (fingerprint collecting surface AB) of the prism 10-3 along 41. The light emitted from the prism 10-33, which is reflected on the fingerprint pattern placed on the fingerprint collection plane AB, passes through the pinhole PH and is formed on the image plane IJ of the light receiver 10-36. It is imaged. As a result, a fingerprint image with contrast is obtained, in which the valleys of the fingerprint are bright and the ridges are dark. The pattern of the collected fingerprint (registered fingerprint) is provided to the processing unit 20 as grayscale image data.

The control unit 20-1 operates the fingerprint input device 10
The image data of the registered fingerprint from the frame memory 20-5.
(Step 902). Then, the center of gravity position is calculated for the captured image data of the registered fingerprint (step 903). The calculation of the position of the center of gravity in this case is performed as follows.

First, the captured registered fingerprint image data (FIG. 11A) is divided into n × m pixels (FIG. 11B). That is, x of the captured registered fingerprint image data
The direction is divided into n pixels, and the y direction is divided into m pixels. The light intensity at the ij-th pixel position is defined as Iij, and the x-coordinate xa and the y-coordinate ya of the center of gravity are obtained by the following equations (1) and (2).

[0037]

(Equation 1)

Then, the calculated center of gravity position (xa, y
a) and the difference (xa−x) between the set center of gravity position (xs, ys)
(s, ya-ys) is obtained as the difference in the center of gravity, and it is checked whether or not there is a difference in the center of gravity (step 904). If there is a center of gravity difference (center of gravity difference ≠ 0), the control unit 2
0-1 adjusts the position of the pinhole PH in the X and Y directions via the pinhole position adjusting mechanism 10-35 (step 905).

When the difference in the center of gravity is eliminated, the control unit 20-1 proceeds to step 906 in response to "NO" in step 904, and the X and Y directions of the image data of the registered fingerprint at that time are determined. The data is captured as image data of the registered fingerprint (step 906). Then, a size calculation is performed on the captured registered fingerprint image data (step 907). The size calculation in this case is performed as follows.

First, the acquired image data of the registered fingerprint whose X and Y directions have been determined (FIG. 12A) is divided into n × m pixels (FIG. 12B). That is, the x direction of the acquired registered fingerprint image data is set to n pixels, and the y direction is set to m pixels.
Divided into pixels. Then, each pixel is binarized at a light level, and a portion with light is set to “1”, and other portions are set to “0”. The light intensity of each pixel after binarization is Dij = “0” or
"1", and the area Sa is represented by the following equation (4).

[0041]

(Equation 2)

The control unit 20-1 compares the area Sa with the set area Ss and checks whether the area Sa is appropriate (step 908). If the area SR is not appropriate (S
a ≠ Ss) and the control unit 20 so that the area Sa is appropriate.
-1 adjusts the position of the pinhole PH in the Z direction via the pinhole position adjustment mechanism 10-3 (step 90).
9). That is, if Sa−Ss> 0, the position of the pinhole PH is moved so as to reduce the fingerprint image,
If Ss <0, the position of the pinhole PH is moved so as to enlarge the fingerprint image.

As a result, if the area Sa becomes an appropriate size, the control unit 20-1 proceeds to “YE” in step 908.
In step 910, the image data of the registered fingerprint at that time is stored in the hard disk 20-4 as the image data of the registered fingerprint whose X, Y, and Z directions are determined.
Create a file corresponding to the number (step 91
0).

[Fingerprint Verification (Pinhole Position Automatic Adjustment)] During operation, the user inputs the ID number assigned to the user using the numeric keypad 10-1 (step 101 shown in FIG. 10), and enters the fingerprint. Guide 10 of device 10-
A finger is placed on the upper surface UP (fingerprint collecting surface AB) of the prism 10-3 along 41. As a result, the pattern of the collected fingerprint (collation fingerprint) is provided to the processing unit 20 as grayscale image data in the same manner as in the case of fingerprint registration.

When the ID number is given via the numeric keypad 10-1, the control unit 20-1 operates the hard disk 20-
The image data of the registered fingerprint corresponding to the ID number is read from the registered fingerprint filed in Step 4 (Step 102). The control unit 20-1 stores the image data of the collation fingerprint from the fingerprint input device 10 in the frame memory 20.
Captured via -5 (step 103). Then, the center-of-gravity position calculation is performed on the captured image data of the verification fingerprint in the same manner as in the case of the registered fingerprint (step 10).
4).

Then, the calculated center of gravity position (xb, y
b) and the difference (xb−x) between the set center of gravity position (xs, ys)
s, yb-ys) is determined as the difference in the center of gravity, and it is checked whether or not there is a difference in the center of gravity (step 105). If there is a center of gravity difference (center of gravity difference ≠ 0), the control unit 2
0-1 adjusts the position of the pinhole PH in the X and Y directions via the pinhole position adjusting mechanism 10-35 (step 106).

When the difference in the center of gravity is eliminated, the control unit 20-1 proceeds to step 107 in accordance with "NO" in step 105, and the X and Y directions of the image data of the collation fingerprint at that time are determined. The image data is captured as image data of the collated fingerprint (step 107). Then, a size calculation is performed on the captured image data of the verification fingerprint in the same manner as in the case of the registered fingerprint (step 108).

Then, the calculated area Sb of the image data of the collation fingerprint whose X and Y directions have been determined is compared with the set area Ss to check whether the area Sb is appropriate (step 109). If the area Sb is not appropriate (Sb ≠ S
s) and the control unit 20-1 so that the area Sb is appropriate.
Adjusts the position of the pinhole PH in the Z direction via the pinhole position adjusting mechanism 10-35 (step 11).
0 ). That is, if Sb−Ss> 0, the position of the pinhole PH is moved so as to reduce the fingerprint image, and
If Ss <0, the position of the pinhole PH is moved so as to enlarge the fingerprint image.

As a result, if the area Sb becomes an appropriate size (Sb = Ss), the control unit 20-1 proceeds to step 10
In response to "YES" in step 9, the process proceeds to step 111, where the fingerprint image at this time is used as the fingerprint image of the collation fingerprint whose X, Y, and Z directions have been determined, and the fingerprint image of this collation fingerprint and the previously read registered fingerprint are registered. Is compared with the fingerprint image (step 111), and the result of the comparison is displayed on the display 10-2 (step 112).

In the flowcharts shown in FIGS. 9 and 10, the position adjustment in the X and Y directions is performed first, and then Z
Although the position adjustment in the direction is performed, the position adjustment in the X and Y directions may be performed after the position adjustment in the Z direction.

In the above-described embodiment, in principle, the optical fingerprint collection plane A'-B 'and the imaging plane IJ are made parallel. This is based on the premise that no distortion occurs between the fingerprint collection plane AB and the optical fingerprint collection plane A′-B ′. However, depending on the positions and angles of the fingerprint collection plane AB and the prism plane RS (see FIG. 1B), the fingerprint collection plane AB and the optical fingerprint collection plane A′-
Distortion is generated between B ′ and B ′.

For example, in the optical system shown in FIG.
When the points P1 to P7 at equal intervals on the fingerprint collection plane AB correspond to the points P1 'to P7' on the optical fingerprint collection plane A'-B ', as shown in FIG. The points P1 'to P7' on the target fingerprint collection plane A'-B 'are not equally spaced, and distortion occurs. In this case, even if the optical fingerprint collection plane A′-B ′ and the imaging plane IJ are parallel, the optical fingerprint collection plane A ′
The distortion generated at −B ′ cannot be removed.

Therefore, in such a case, that is, when the optical fingerprint collection plane A'-B 'has distortion with respect to the fingerprint collection plane AB, the distortion on the optical fingerprint collection plane A'-B' is removed. For this purpose, the image plane IJ is rotated by a required angle about the point PO to obtain UT (see FIG. 13A). As a result, as shown in FIG. 13C, distortion generated on the optical fingerprint collection plane A′-B ′ can be significantly reduced.

In the above-described embodiment, since the optical fingerprint collection surface A′-B ′ is a curved surface, it is difficult to completely remove the distortion. With the configuration as shown in FIG. 14, distortion can be completely removed.

That is, the second prism 4 is provided in front of the image plane IJ. Then, the fingerprint collection plane AB of the first prism 1 and the imaging plane IJ are made parallel, and the fingerprint collection plane AB of the first prism 1 and the second prism 4
Are parallel to the surface LM on the image-forming side of the first prism 1
The exit surface CD to the pinhole PH and the second prism 4
Is parallel to the incident surface KM from the pinhole PH.
In this example, the surface LM of the second prism 4 is placed on the image plane IJ.

As a result, the optical system on the first prism 1 side and the optical system on the second prism 4 side are similar to each other with the pinhole PH (point O) as the center, and distortion can be completely removed. And blur and distortion can be eliminated at the same time. The fingerprint collection plane AB and the imaging plane I-
Some deviation from the parallelism with J, the parallelism between the fingerprint collection plane AB and the plane LM, and the parallelism between the exit plane CD and the entrance plane KM are allowed.

Further, in the above-described embodiment, a triangular prism 1 (10-33) is used, but a rectangular prism 1 '(10-3) as shown in FIG.
3 ') and the like, and various prisms may be used. In FIG. 15, the diffusion plate 10-32 may be attached to the side of the prism 1 '(10-33') as shown by a dotted line in the figure.

The prism is defined as an optical element having two or more planes and utilizing refraction and reflection of light. Functionally, it is divided into the following. One or more reflection functions are combined into one block, and the optical path is folded and moved in a compact arrangement. Using the refraction of light, the direction of light is changed, and the direction (direction) of an image is adjusted. The spectrum of light is analyzed using the dispersion of the optical material.

Further, in the above-described embodiment, the case where the total reflection method is adopted for the fingerprint input unit 10-3 has been described, but the same processing operation can be applied to the case where the optical path separation method is adopted. Neither the total reflection method nor the optical path separation method is superior.

[0060]

As is apparent from the above description, according to the present invention, the light emitted from the prism reflected by the pattern of the finger placed directly or indirectly on the fingerprint collecting surface is obtained.
After passing through the pinhole, the image is formed on the imaging surface which is almost parallel to the optical fingerprint collection surface of the prism,
The optical path ratio is kept constant, and one point on the fingerprint collecting surface is formed on one point on the image forming surface, so that blur and distortion can be greatly reduced. Further, in another invention, the optical system on the first prism side and the optical system on the second prism side are similar to each other with the pinhole as a center, and the finger pattern surface directly or indirectly placed on the fingerprint collecting surface. The reflected light from the first prism passes through the pinhole, passes through the second prism, and forms an image on the image plane, so that blurring and distortion can be eliminated at the same time. become.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an optical system of a fingerprint input device according to the present invention.

FIG. 2 is a block diagram of a fingerprint collation system using the fingerprint input device according to the present invention.

FIG. 3 is an enlarged view showing the fingerprint input unit (total reflection method) shown in FIG. 2 and a conventional fingerprint input unit corresponding thereto.

FIG. 4 is an enlarged view showing a fingerprint input unit when an optical path separation method is adopted and a conventional fingerprint input unit corresponding thereto.

FIG. 5 is an external view and a plan view of the fingerprint input device shown in FIG. 2;

FIG. 6 is a diagram illustrating a display state of a fingerprint image during a registration operation and a collation operation.

FIG. 7 is a flowchart for explaining a fingerprint registration operation (manual adjustment of a pinhole position) in the fingerprint collation system.

FIG. 8 is a flowchart for explaining a fingerprint collating operation (manual adjustment of a pinhole position) in the fingerprint collating system.

FIG. 9 is a flowchart for explaining a fingerprint registration operation (pinhole position automatic adjustment) in the fingerprint collation system.

FIG. 10 is a flowchart for explaining a fingerprint collating operation (automatic pinhole position adjustment) in the fingerprint collating system.

FIG. 11 is a diagram for explaining calculation of a center of gravity position at the time of automatic adjustment of a pinhole position.

FIG. 12 is a diagram for explaining size calculation at the time of automatic adjustment of a pinhole position.

FIG. 13 shows a fingerprint collection plane AB and an optical fingerprint collection plane A ′.
It is a figure explaining the countermeasure for reducing the distortion produced between -B '.

FIG. 14 is a diagram illustrating a measure for completely removing distortion caused by a curved optical fingerprint collection surface A′-B ′.

FIG. 15 is an enlarged view showing a fingerprint input unit (total reflection method) when a rectangular prism is used.

FIG. 16 is a diagram showing a main part of an optical system of a conventional fingerprint input device.

[Explanation of symbols]

1: Prism, AB: Fingerprint collecting surface, A'-B ': Optical fingerprint collecting surface, C'-D': Pinhole plate surface, PH: Pinhole, O: Center of pinhole, IJ ... imaging plane, 1
0: fingerprint input device, 10-1: numeric keypad, 10-2: display (LCD), 10-3: fingerprint input unit, 10-
31 ... Light source (LED), 10-32 ... Diffusion plate, 10-3
3: Prism, 10-34: Pinhole plate, 10-35
... Pinhole position adjustment mechanism, 10-36 ... Receiver, 20
... Processing unit.

Continuation of the front page (56) References JP-A-2-176984 (JP, A) JP-A-4-78979 (JP, A) JP-A-4-78980 (JP, A) JP-A-2-50782 (JP) JP-A-3-292578 (JP, A) JP-A-5-6423 (JP, A) JP-A-8-334691 (JP, A) JP-A-9-179969 (JP, A) 63-99960 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06T 1/00 400

Claims (7)

(57) [Claims] A prism disposed on one side thereof as a fingerprint collecting surface; a light source for irradiating the fingerprint collecting surface with light through the interior of the prism; A pinhole provided in a passage of light emitted from the prism after being reflected by a pattern surface of a finger placed opposite thereto; and an imaging surface on which emission light from the prism passing through the pinhole is imaged. A fingerprint input device which is equivalent to a fingerprint collection surface of the prism when the prism is replaced with air, and the imaging surface are substantially parallel to each other. 2. The fingerprint input device according to claim 1, wherein when the optical fingerprint collecting surface has a distortion with respect to the fingerprint collecting surface, the image forming surface is rotated by a required angle. 3. A first prism having its one-way surface arranged as a fingerprint collecting surface, a light source for irradiating the fingerprint collecting surface with light through the interior of the first prism, and A pinhole provided in a passage of light that is incident on the prism and is reflected by a finger pattern placed on the fingerprint collecting surface and emitted from the first prism; and a pinhole that passes through the pinhole. An imaging surface on which the light emitted from the first prism is imaged; and a second prism placed in front of the imaging surface, the fingerprint collecting surface of the first prism and the imaging surface Are substantially parallel to each other, and the fingerprint collection surface of the first prism and the surface of the second prism on the image forming surface side are substantially parallel to each other;
A fingerprint input device, wherein an exit surface of the first prism to the pinhole and an entrance surface of the second prism from the pinhole are substantially parallel. 4. The fingerprint input device according to claim 1, further comprising a pinhole position adjusting means for adjusting the position of the pinhole. 5. The fingerprint according to claim 4, wherein said pinhole position adjusting means comprises a manual adjustment mechanism, and further comprises a display unit for displaying a fingerprint image formed on said image plane. Input device. 6. The fingerprint input device according to claim 4, wherein said pinhole position adjusting means automatically adjusts said pinhole position. 7. The fingerprint input device according to claim 1, wherein the light source is an LED or a laser light irradiator.