JP3709344B2 - Fingerprint image input method, fingerprint image input device, program, portable information device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fingerprint reading device, and more particularly to a fingerprint reading technique for correcting deformation during reading using a two-line sensor.
[0002]
[Prior art]
Conventionally, a two-dimensional sensor has been used for fingerprint reading.
[0003]
Japanese Laid-Open Patent Publication No. 63-273976 “Fingerprint Data Reading Device” discloses a fingerprint data reading device using a one-line sensor.
[0004]
[Problems to be solved by the invention]
With the conventional two-dimensional sensor, it has been difficult to provide a fingerprint sensor with a further low cost and space saving for a mobile phone or a portable information terminal.
[0005]
Japanese Patent Application Laid-Open No. 63-273976 “Fingerprint data reading device” does not disclose anything about obtaining an image without deformation.
[0006]
[Means for Solving the Problems]
The first fingerprint image input device of the present invention is based on a fingerprint image obtained by sweeping a finger on a one-dimensional sensor comprising two lines of a first line sensor and a second line sensor arranged at a distance. A fingerprint image input device for obtaining a two-dimensional fingerprint image, the fingerprint image input device comprising: a first buffer; a second buffer; a corrected image storage memory for storing the fingerprint image; A first means for inputting and storing fingerprint images from one line sensor and the second line sensor into the first buffer and the second buffer; and a predetermined number of first zones in the first buffer. And the second buffer is divided into a predetermined number of second zones, and the image blocks determined to be the same from the correlation of the fingerprint images stored in the first zone and the second zone Detecting the first zone A second means for determining the moving speed of the finger in the screen, and detecting a distortion of the reduction or enlargement of the fingerprint image from the moving speed for each of the first zones, and correcting the distortion by a predetermined method. It comprises third means for storing in the image storage memory.
[0008]
The first fingerprint image input method of the present invention is based on a fingerprint image obtained by sweeping a finger on a one-dimensional sensor composed of two lines of a first line sensor and a second line sensor arranged at a distance. A fingerprint image input method for obtaining a two-dimensional fingerprint image, wherein the fingerprint image is input from the first line sensor and the second line sensor to the first buffer and the second buffer for storage. A second step of dividing the first buffer into a predetermined number of first zones and dividing the second buffer into a predetermined number of second zones; A third step of detecting an image block determined to be the same from the correlation between the fingerprint image stored in the zone and the second zone and determining the moving speed of the finger in the first zone; The moving speed for each zone Detecting a distortion of the reduced or enlarged in al the fingerprint image consists of a fourth step of correcting the distortion by a predetermined method.
[0010]
Portable information apparatus of the present invention inputs a fingerprint using the input equipment of the present invention the first fingerprint image is available by the authentication by the fingerprint image.
[0011]
The program according to the present invention generates a two-dimensional fingerprint image from a fingerprint image obtained by sweeping a finger on a one-dimensional sensor composed of two lines of a first line sensor and a second line sensor arranged at a distance. A first step of inputting a fingerprint image from the first line sensor and the second line sensor to the first buffer and the second buffer and storing them in the first buffer; A second step of dividing the second buffer into a predetermined number of second zones, and storing the second buffer into a predetermined number of second zones, and storing in the first zone and the second zone A third step of detecting image blocks determined to be the same from the correlation of the fingerprint images and determining the moving speed of the finger in the first zone; and the fingerprint from the moving speed for each first zone. Reduce image Others Ru to execute the fourth step of correcting by a predetermined method the distortion detecting a distortion of the expansion into the computer.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a fingerprint image input apparatus according to an embodiment of the present invention. The fingerprint image input device according to the embodiment of the present invention includes a sensor 10, a control unit 20, and a processing unit 30.
[0013]
FIG. 2 is a block diagram showing a configuration of the two-line sensor 10 used in the fingerprint image input apparatus according to the embodiment of the present invention. As shown in FIG. 2, the sensor 10 is composed of two line sensors, an A line 11 and a B line 12, with an interval of 1.0 mm, and each line sensor is configured with a width of 384 pixels of 19.2 mm at a pitch of 50 μm. At the same time, scanning is driven. The finger 40 contacts the sensor 10 and is swept from the top to the bottom in the direction of the arrow. Fingerprint image data detected by the A line 11 and the B line 12 of the sensor 10 is sequentially stored in the A buffer 21 and the B buffer 22 of the control unit 20.
[0014]
FIG. 3 is a diagram showing the sensor amplifier 18 and the AD converter 19 in the two-line sensor 10 according to the embodiment of the present invention. The fingerprint image captured by the A line 11 passes through the sensor amplifier 18 and is converted into a digital signal by the AD converter 19 and stored in the A buffer 21. The fingerprint image captured by the B line 12 passes through the sensor amplifier 18 and is converted into a digital signal by the AD converter 19 and stored in the B buffer 22.
[0015]
When the fingerprint image data for one finger is stored, the control unit 20 notifies the processing unit 30 (for example, a programmable small processor including a CPU, ROM, RAM, and I / O) of processing ready. The processing unit 30 analyzes the speed of the finger 40 from the fingerprint image data in the A buffer 21 and the B buffer 22 and corrects the deformation of the fingerprint image data due to the speed fluctuation.
[0016]
Next, the operation of the embodiment of the present invention will be described with reference to the drawings. First, detection of the finger moving speed will be described. FIG. 4 is a diagram showing a fingerprint image stored in the buffer of the fingerprint image input device according to the embodiment of the present invention. FIG. 5 is a flowchart showing an operation of detecting the moving speed from the fingerprint stored in the buffer of the fingerprint image input device according to the embodiment of the present invention.
[0017]
The images scanned by the A line 11 and the B line 12 of the sensor 10 are sequentially stored in the A buffer 21 and the B buffer 22 of the control unit 20 when a fingerprint image is detected by the A line 11 (step A-1). (Step A-2). When the fingerprint image data from the A line 11 detects the upper end of the finger, that is, the white line for a plurality of lines, the control unit 20 stops the storage (step A-3). The addresses of the A buffer 21 and the buffer B at the time of the stop are acquired as stop line addresses (step A-4).
[0018]
Since the A line 11 and the B line 12 have an interval of 1.0 mm and the B line 12 is delayed from the A line 11 with respect to the sweep (sweep) direction, the B buffer 22 includes the A buffer 21. For the stored fingerprint image, delayed fingerprint image data correlated with the finger speed is stored. A fingerprint image portion A 100 stored in the A buffer 21 corresponds to a fingerprint image portion B 101 stored in the B buffer 22. Since the speed of the finger is assumed to change during the sweep (sweep), the speed of the sweep (sweep) is obtained as follows.
[0019]
The A buffer 21 and the B buffer 22 are divided into four zones, for example, each zone of 64 lines, A1 to A4, B1 to B4, and search start points S1 and S2 from the stop line address that is the address of the buffer that stopped storing the fingerprint image. , S3 and S4 are obtained (step A-5). The search is performed above the search start point S4 of the B4 zone, and an image block B111 determined to be the same as the image block A110 of the A4 zone by the image correlation is detected, and the number of lines n4 from the search start point S4 is calculated (step A- 6). The number of lines in the image block is, for example, 8 lines. For other zones, the number of lines n3, n2, and n1 is obtained by the same method (step A-7). As a result, the number of lines required to move the line interval of 1.0 mm for each zone can be specified, and the time for scanning the sensor 10 is constant, so that the moving speed, that is, the number of lines is calculated. (Step A-8).
[0020]
Next, a method for correcting the deformation of the fingerprint image will be described. Now, the speed when the finger is swept the earliest allowed is 50 mm / second, and one scanning time of the sensor 10 is 1 mS. Accordingly, when the finger is swept at the maximum constant speed (sweep), the time required to move between 1 mm is 20 mS. Therefore, fingerprint images shifted by 20 scans (lines) are displayed in the A buffer 21 and the B buffer 22. Will be remembered. Since it is actually slower than the maximum speed, the image shift between the A buffer 21 and the B buffer 22 is larger than 20 scans (lines).
[0021]
FIG. 6 is a diagram showing the division of the fingerprint image stored in the buffer into zones when the fingerprint image is corrected by the fingerprint image input apparatus according to the embodiment of the present invention. FIG. 7 is a flowchart showing the fingerprint image deformation correcting operation of the fingerprint image input apparatus according to the embodiment of the present invention. In the description of the calculation of the moving speed in FIGS. 4 and 5, it has been described that the four zones are divided into 64 zones. However, in the correction of the fingerprint image described below, the fingerprint image is divided into N zones every 64 lines. The case of performing will be described.
[0022]
The number of scans (lines) of 1 mm for each zone from the zone A1 to the zone of the B buffer 22 corresponding to the zone An obtained by dividing the fingerprint image stored in the A buffer 21 of FIG. 6 into N zones every 64 lines. Calculation is performed by the method described in the above description of FIG. 5, and the movement speed in each zone, that is, the number of movement lines n1 is obtained (step B-1).
[0023]
When sweeping at a constant speed of 50 mm / sec at the maximum speed, the number of lines n1 to nn is all 20. Since the number of scans 20 when the maximum speed is constant is changed from n1 to nn, each zone is enlarged and deformed from n1 / 20 to nn / 20. Accordingly, the fingerprint image stored in the A buffer 21 is inversely converted in the following manner for each zone, thereby correcting the distortion of the fingerprint image due to fine speed fluctuations. The number of lines is corrected so that the fingerprint image in the zone A1 has the number of lines indicated by 64 × 20 / n1, the number of lines indicated by the zone A2 is 64 × 20 / n2,..., The zone An is 64 ×. The fingerprint image is corrected so that the number of lines indicated by 20 / nn is obtained. That is, the fingerprint image in the line direction is sequentially reduced to 64 × 20 / n1 in the line direction from the A1 zone of the A buffer 21 and stored in the corrected image memory area 29.
[0024]
As a fingerprint image reduction method, for example, there are the following methods. If the line is reduced by a factor of 2, only odd lines are written into the corrected image memory area 29. In addition, there is a correction method such as thinning out a part of a line every several lines when it is not divisible, such as half.
[0025]
The number of lines n1 ′ after reduction is 64 × 20 / n1 (step B-2). The process of zone N shown in step B-2 is performed until the sum of n1 ′ to nn ′ becomes equal to or greater than the number of lines necessary for subsequent fingerprint image processing (step B-3). You may perform the process of step B-2 with respect to all the N zones.
[0026]
Next, try to estimate the size of the buffer. If the image size sufficient for fingerprint verification is 25 mm from the upper end of the finger, the latest allowable sweep (sweep) is 1000 scans at a scan speed of 1 mS per second and the required buffer size is If the width of the sensor 10 is 19.2 mm for 1000 scans, 384 × 1000 = 375 KB.
[0027]
In the above description, two lines of sensors are scanned simultaneously. However, after scanning the A line 11, the B line 12 may be scanned. FIG. 8 is a diagram when the sensor amplifier 18 and the AD converter 19 are combined into one set in the fingerprint image input apparatus according to another embodiment of the present invention. In this case, the sensor amplifier 18 and the AD converter 19 are made into one set by performing time division, that is, alternately with the A line 11 and the B line 12 without simultaneously scanning the two lines. In short, it is sufficient that the difference between the A line 11 and the B line 12 is clear.
[0028]
Each step described above can be realized by a program of the computer 60. FIG. 9 is a diagram showing a program for causing the computer 60 to execute the fingerprint image input method according to the embodiment of the present invention, and a recording medium 61 for storing the program.
[0029]
The fingerprint image input device described above can be applied to information equipment. FIG. 10 is a diagram illustrating an example of the portable information device 90 having the fingerprint image input device according to the embodiment of the present invention. The 2-line sensor is mounted on the lower front surface of the mobile phone as shown in FIG. 10 taking advantage of the small area. Fingerprint authentication is performed using the fingerprint image input from the fingerprint image input device, and the mobile phone can be used.
[0030]
【The invention's effect】
In this manner, by detecting the finger sweep (sweep) speed fluctuation due to the difference in operator and the speed fluctuation within the same finger, the deformation of the fingerprint image due to the speed fluctuation can be accurately corrected. In addition, since the sensor is a two-line sensor, the area of the sensor is very small compared to a two-dimensional sensor, which is 1/100 to 1/200, so the cost is greatly reduced. Further, since it can be made very small, it can be easily mounted on a small device such as a portable information terminal or a cellular phone. As an application in a mobile phone or the like, since it can be used to substitute a personal identification number by fingerprint authentication, higher security than the personal identification number can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a fingerprint image input apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a two-line sensor 10 used in the fingerprint image input device according to the embodiment of the present invention.
3 is a diagram showing a sensor amplifier 18 and an AD converter 19 in the two-line sensor 10 according to the embodiment of the present invention. FIG.
FIG. 4 is a diagram showing a fingerprint image stored in a buffer of the fingerprint image input device according to the embodiment of the present invention;
FIG. 5 is a flowchart showing an operation for detecting a moving speed from a fingerprint stored in a buffer of the fingerprint image input device according to the embodiment of the present invention;
FIG. 6 is a diagram illustrating division of a fingerprint image stored in a buffer into zones when the fingerprint image is corrected by the fingerprint image input device according to the embodiment of the present invention.
FIG. 7 is a flowchart showing a fingerprint image deformation correcting operation of the fingerprint image input device according to the embodiment of the present invention;
FIG. 8 is a diagram showing a case where a sensor amplifier 18 and an AD converter 19 are combined into one set in a fingerprint image input apparatus according to another embodiment of the present invention.
FIG. 9 is a diagram showing a program for causing a computer 60 to execute a fingerprint image input method according to an embodiment of the present invention and a recording medium 61 for storing the program.
FIG. 10 is a diagram showing an example of a portable information device 90 having a fingerprint image input device according to an embodiment of the present invention.
[Explanation of symbols]
10 sensor 11 A line 12 B line 18 sensor amplifier 19 AD converter 20 control unit 21 A buffer 22 B buffer 29 corrected image memory area 30 processing unit 40 finger 60 computer 61 recording medium 90 portable information device 100 part A
101 Part B
110 Image Block A
111 Image block B

Claims (4)

    Fingerprint image input method for obtaining a two-dimensional fingerprint image from a fingerprint image obtained by sweeping a finger on a one-dimensional sensor comprising two lines of a first line sensor and a second line sensor arranged at a distance A first step of inputting a fingerprint image from the first line sensor and the second line sensor to the first buffer and the second buffer and storing the fingerprint image; A second step of dividing the second buffer into a predetermined number of second zones, and storing the first buffer and the second zone stored in the second zone A third step of detecting image blocks determined to be identical from the correlation of fingerprint images and determining the moving speed of the finger within the first zone; and the fingerprint image of the fingerprint image from the moving speed for each first zone. Reduced or enlarged Input method of a fingerprint image, characterized by comprising a fourth step of detecting a Gami corrects the distortion by a predetermined method.   Fingerprint image input device for obtaining a two-dimensional fingerprint image from a fingerprint image obtained by sweeping a finger on a one-dimensional sensor comprising two lines of a first line sensor and a second line sensor arranged at a distance The fingerprint image input device includes a first buffer, a second buffer, a corrected image storage memory for storing the fingerprint image, and a fingerprint image from the first line sensor and the second line sensor. First means for inputting and storing images into the first buffer and the second buffer; dividing the first buffer into a predetermined number of first zones; and Divided into a plurality of second zones, image blocks determined to be identical from the correlation of the fingerprint images stored in the first zone and the second zone are detected, and the finger blocks are detected in the first zone. Determine the movement speed of Second means and third means for detecting distortion of the reduction or enlargement of the fingerprint image from the moving speed for each of the first zones, correcting the distortion by a predetermined method, and storing the distortion in the corrected image storage memory. An input device for a fingerprint image. A portable information device which can be used by inputting a fingerprint using the fingerprint image input device according to claim 2 and authenticating with the fingerprint image.   A program for obtaining a two-dimensional fingerprint image from a fingerprint image obtained by sweeping a finger on a one-dimensional sensor comprising two lines of a first line sensor and a second line sensor arranged at a distance, A first step of inputting a fingerprint image from the first line sensor and the second line sensor to a first buffer and a second buffer and storing the fingerprint image; and a predetermined number of first buffers. A second step of dividing the second buffer into a predetermined number of second zones, and correlating the fingerprint images stored in the first zone and the second zone; A third step of detecting image blocks determined to be identical from the first zone and determining the moving speed of the finger in the first zone; and reduction or enlargement of the fingerprint image from the moving speed for each first zone. Distortion Program for executing a fourth step of correcting the distortion by a predetermined method out on the computer.

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