Image analysis – Applications – Personnel identification
Reexamination Certificate
1998-01-13
2001-11-13
Bella, Matthew C. (Department: 2621)
Image analysis
Applications
Personnel identification
C382S126000, C382S312000, C235S439000, C235S445000, C235S447000, C235S451000
Reexamination Certificate
active
06317508
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to methods of and systems for capturing fingerprint images, and more particularly to a semiconductor capacitive fingerprint scanning device.
DESCRIPTION OF THE PRIOR ART
Fingerprint recognition has been suggested for use in many security applications such as controlling access to buildings, computers, or the like. Fingerprint recognition systems enable a user to access the controlled facility without a device such as a key or smart card or without having to memorize a password or other personal identification number.
The sensing device is an important part of a fingerprint recognition system and the quality of the representation of the fingerprint that the device produces will affect recognition capability and the amount of processing required for verification of the fingerprint. Various technologies have been proposed for use in fingerprint sensing devices. One commonly proposed technology involves optical detection. Examples of optical fingerprint detection devices are disclosed in Jensen, U.S. Pat. No. 4,784,484; Fishbine, et al., U.S. Pat. No. 5,467,403; and Giles, et al., U.S. Pat. No. 5,548,394.
Optical detectors include a glass surface upon which a subject places his finger to be recognized. Optical detectors may present recognition problems when the glass surface or the subject's finger is wet. The optics of the detectors are constructed based upon the indices of refraction of air and glass. When water or perspiration is between the glass and the surface of the finger, the operation of the detector is affected.
In addition to optical sensors, various electrical sensor systems have been proposed, as for example in Knapp, U.S. Pat. No. 5,325,442; Tamori, U.S. Pat. No. 5,400,662; and Tamori, U.S. Pat. No. 5,429,006. The electrical detection devices typically comprise an array of sense elements. The individual sense elements respond with an output that depends upon whether a fingerprint ridge or valley is located over the sense element.
The electrical detection devices offer advantages over the optical detection devices. However, an electrical detector that is large enough to detect a fingerprint is a large and expensive semiconductor device. For example, the TouchChip (TM) Silicon Fingerprint Sensor (STFP
2015-50
) available from SGS-Thomson Microelectronics has an active sensor surface measuring 19.2 mm by 12.8 mm that includes a 384 by 256 sensor array. Accordingly, electrical detection device tend to be more expensive than optical detectors.
It is an object of the present invention to provide a fingerprint detecting device that overcomes the shortcomings of the prior art.
SUMMARY OF THE INVENTION
The present invention provides a scanning fingerprint detection system that includes an array of capacitive sensing elements. The array has a first dimension about the width of a fingerprint and a second dimension substantially less than the length of a fingerprint. Each of the capacitive sensing elements has a size less than the width of a fingerprint ridge. Circuitry is provided for scanning the array to capture an image of a portion of fingerprint and for assembling the captured images into a fingerprint image as a fingerprint is moved over the array.
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Thomson-CSF Semiconducteurs Specifiques, Introducing the FingerChip™: The silicon chip fingerprint sensor from Thomson-CSF Semiconducteurs Specifiques, ©1997 TCS, 2 pp.
©1997 SGS-Thomson Microelectronics, TouchChip™ Silicon Fingerprint Sensor, Nov. 1997, 6 pp.
Press Release Communique De Presse Communicato Stampa Presseinformation, SGS-Thomson's Silicon Fingerprint Sensor Offers Cost-effective Biometric Solution for Security, Comdex, Las Vegas—Nov. 17, 1997, 2 pp.
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Brady James
Kramer Alan
Bella Matthew C.
Chawan Sheela
Jorgenson Lisa K.
STMicroelectronics Inc.
Thoma Peter J.
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