Swiped aperture capacitive fingerprint sensing systems and methods
First Claim
1. Finger sensing apparatus comprising:
- two or more finger detectors spaced apart along an expected direction of movement of a finger, each of said finger detectors including at least one drive plate and at least one pickup plate, wherein said finger detectors are dimensioned and spaced to sense a bulk of a finger rather than fingerprint features and wherein an end of a finger passing over each of said finger detectors produces a change in capacitance between respective drive plates and pickup plates;
an excitation circuit for energizing the drive plates of said finger detectors with drive signals;
a detection circuit for detecting the drive signals capacitively coupled from the drive plate to the pickup plate of each of said finger detectors to provide sensor signals; and
a processing circuit for determining a time delay between said sensor signals from said finger detectors, wherein said time delay between said sensor signals is representative of a speed of the finger.
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Abstract
A fingerprint sensing system includes an image sensor, a rate sensor and a sensor circuit. The image sensor includes a linear array of capacitive sensors for capacitive sensing of ridge peaks and ridge valleys of a fingerprint on a swiped finger. The rate sensor senses the speed of the finger as it is swiped across the image sensor. The sensor circuit supplies image drive signals to the image sensor and detects image signals in response to the drive signals. The sensor circuit supplies rate drive signals to the rate sensor and detects rate signals in response to the rate drive signals. The sensor circuit further coordinates the image signals and the rate signals to provide a fingerprint image. The image sensor may be configured as an image pickup plate and multiple image drive plates formed on a substrate, such as a flexible printed circuit board or other flexible substrate which may conform to the shape of the finger.
160 Citations
16 Claims
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1. Finger sensing apparatus comprising:
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two or more finger detectors spaced apart along an expected direction of movement of a finger, each of said finger detectors including at least one drive plate and at least one pickup plate, wherein said finger detectors are dimensioned and spaced to sense a bulk of a finger rather than fingerprint features and wherein an end of a finger passing over each of said finger detectors produces a change in capacitance between respective drive plates and pickup plates; an excitation circuit for energizing the drive plates of said finger detectors with drive signals; a detection circuit for detecting the drive signals capacitively coupled from the drive plate to the pickup plate of each of said finger detectors to provide sensor signals; and a processing circuit for determining a time delay between said sensor signals from said finger detectors, wherein said time delay between said sensor signals is representative of a speed of the finger. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A fingerprint sensing system comprising:
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an image sensor comprising an array of sensors for sensing ridge peaks and ridge valleys of a fingerprint; and a finger sensor comprising two or more finger detectors spaced apart along an expected direction of movement of a finger, each of said finger detectors including at least one drive plate and at least one pickup plate, wherein said finger detectors are dimensioned and spaced to sense a bulk of a finger rather than fingerprint features and wherein an end of a finger passing over each of said finger detectors produces a change in capacitance between respective drive plates and pickup plates; an excitation circuit for energizing the drive plates of said finger detectors with drive signals; a detection circuit for detecting the drive signals capacitively coupled from the drive plate to the pickup plate of each of said finger detectors to provide sensor signals; and a processing circuit for determining a time delay between said sensor signals from said finger detectors, wherein said time delay between said sensor signals is representative of a speed of the finger. - View Dependent Claims (16)
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Specification