Fingerprint-reading system
DCFirst Claim
Patent Images
1. A fingerprint reading system comprising:
- means for reading a fingerprint including a sensor having a sensing surface coupled to a matrix of contact sensitive elements for generating a series of partial images of a finger, placed in direct contact with said sensing surface, from relative sliding contact between said sensing surface and said finger, said sensing surface having a surface area smaller than a surface area of said fingerprint to be read; and
means for reconstituting a total image of the fingerprint from said partial images.
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Abstract
A fingerprint-reading system includes a fingerprint sensor having an active surface sensitive to the pressure and temperature of a finger. The surface area of this sensor is far smaller than the surface area of the fingerprint to be read. The reading is done when the sensor and the finger are in contact and in a relative motion of sliding of the sensor and the finger with respect to each other. The system reconstitutes a complete image of the fingerprint from the partial images given by the sensor during this motion.
477 Citations
20 Claims
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1. A fingerprint reading system comprising:
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means for reading a fingerprint including a sensor having a sensing surface coupled to a matrix of contact sensitive elements for generating a series of partial images of a finger, placed in direct contact with said sensing surface, from relative sliding contact between said sensing surface and said finger, said sensing surface having a surface area smaller than a surface area of said fingerprint to be read; and
means for reconstituting a total image of the fingerprint from said partial images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
means for reading a fingerprint including said sensor for providing said series of partial images of said finger corresponding to respective portions of said finger directly in contact with a surface of said sensor.
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10. A fingerprint-reading system according to any of the claims 2, 3 or 1, wherein the sensor takes the form of a small bar with a length far smaller than its width.
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11. A fingerprint-reading system according to claim 10, wherein the width of the small bar is substantially equal to that of a finger.
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12. A fingerprint-reading system according to claim 10, wherein the sensor has an active surface whose width ranges from about 1 centimeter to 2.5 centimeters and whose length is smaller than 5 millimeters.
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13. A fingerprint-reading system according to any of the claims 2, 3 or 1, wherein the sensor comprises only one row of sensitive elements.
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14. A fingerprint-reading system according to any one of the claims 2, 3 or 1 comprising, for the reconstruction of an image of a fingerprint, an electronic circuit with a microprocessor, a read-only memory programmed with an algorithm enabling the reconstruction of the complete image of the fingerprint and the identification of the individual, and a read-only memory.
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15. A fingerprint-reading system according to any one of the claims 2, 3 or 1, comprising partial image processing means provided by the sensor, making it possible in particular to provide contours of fingerprint ridge lines, the image reconstitution means setting up, on the basis of these contours, a total fingerprint image in the form of contours.
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16. A fingerprint-reading system according to claim 15, wherein the partial image-processing means take account of the results preceding a new search for optimal superimposition between two successive images to predict the most probable position of overlapping for the next image by the fact that there is a very high probability that the relative shift of the finger with respect to the sensor will be substantially constant.
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17. A fingerprint reading system comprising:
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means for reading a fingerprint including a sensor having a sensing surface coupled to a matrix of several lines of sensing elements for generating a series of overlapping successive partial images of a finger placed in contact with said sensing surface from relative sliding contact between said sensing surface and said finger, said sensing surface having a surface area smaller than a surface area of said fingerprint to read; and
means for reconstituting a total image of the fingerprint from said overlapping partial images. - View Dependent Claims (18, 19, 20)
means for determining a number of said sensitive elements having substantially identical signal values in an area of overlap between two successive partial images;
means for comparing said number to a predetermined number; and
means for adjusting a size of said area of overlap if said number is less than said predetermined number.
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19. A fingerprint reading system according to claim 17, wherein:
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said means for reading generates first, second and third successive partial images; and
said means for reconstituting comprises;
means for matching said first and second successive images and form a first combined image; and
means for matching said third successive image with said first combined image to form a second combined image.
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20. A fingerprint reading system according to claim 17, wherein:
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said means for reading generates first and second successive partial images; and
said means for reconstituting comprises means for adjusting a relative position of said first and second partial images in at least two orthogonal directions to match said first and second partial images.
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Specification