SENSING ELEMENT ARRAGEMENT FOR A FINGERPRINT SENSOR
First Claim
1. A fingerprint sensing device having a plurality of pixels formed within semiconductor and dielectric material, the dielectric material disposed atop the semiconductor material and having flat exposed surface portions, one or more of said pixels comprising:
- a surface plate retained by dielectric material at a sensing surface, the surface plate having an upper surface that defines the sensing surface with surrounding surface portions of the dielectric material;
first and second electrodes embedded in the dielectric material at a level beneath the surface plate; and
an amplifier having an input connected to the second electrode and an output for generating a pixel output signal in response to an input pulse applied to the first electrode;
wherein a fingerprint sensor having a variable impedance is formed by the surface plate and a portion of a fingerprint-bearing skin of a user'"'"'s finger applied to the sensing surface, said portion being disposed above the surface plate with the skin applied to the sensing surface, wherein first and second sensors are formed between the surface plate and the respective first and second embedded electrodes, and wherein the pixel output signal varies with the impedance value of the fingerprint sensor to indicate the proximity of the skin of the user'"'"'s finger to the surface plate when an input pulse is applied to the first electrode.
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Accused Products
Abstract
For each pixel in an array of pixels in a fingerprint sensor, a fingerprint capacitor is defined by the fingerprint-bearing skin of a user'"'"'s finger proximate to the top exposed surface of a sensing plate of the pixel. First and second plates are embedded in dielectric material beneath the sensing plate, and define therewith first and second capacitors of a sensing element. The capacitance of the fingerprint capacitor is coupled by the sensing element to an amplifier. During a sensing operation, the amplifier generates a pixel output signal that is a function of the variable capacitance of the fingerprint capacitor, which varies according to the presence of a fingerprint ridge or valley appearing directly above the sensing plate when the user'"'"'s finger is in contact with the fingerprint sensor.
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Citations
7 Claims
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1. A fingerprint sensing device having a plurality of pixels formed within semiconductor and dielectric material, the dielectric material disposed atop the semiconductor material and having flat exposed surface portions, one or more of said pixels comprising:
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a surface plate retained by dielectric material at a sensing surface, the surface plate having an upper surface that defines the sensing surface with surrounding surface portions of the dielectric material;
first and second electrodes embedded in the dielectric material at a level beneath the surface plate; and
an amplifier having an input connected to the second electrode and an output for generating a pixel output signal in response to an input pulse applied to the first electrode;
wherein a fingerprint sensor having a variable impedance is formed by the surface plate and a portion of a fingerprint-bearing skin of a user'"'"'s finger applied to the sensing surface, said portion being disposed above the surface plate with the skin applied to the sensing surface, wherein first and second sensors are formed between the surface plate and the respective first and second embedded electrodes, and wherein the pixel output signal varies with the impedance value of the fingerprint sensor to indicate the proximity of the skin of the user'"'"'s finger to the surface plate when an input pulse is applied to the first electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification