Active matrix capacitive fingerprint sensor for display integration based on charge sensing by a 2-TFT pixel architecture
First Claim
1. An input device, comprising:
- an array of sensing pixels configured to sense an input object in a sensing region, each of the sensing pixels comprising;
a sense element configured to store charge proportional to a feature of the input object;
a first transistor comprising;
a gate terminal connected to a row select line; and
a second terminal connected to the sense element, wherein the first transistor is configured to;
couple the sense element with an enable line in response to a high assertion of the row select line; and
isolate the sense element from the row select line in response to a low assertion of the row select line; and
a non-linear circuit element, wherein the non-linear circuit element comprises;
a first non-linear circuit element terminal connected to the sense element and the second terminal of the first transistor; and
a second non-linear circuit element terminal connected to a column output line, wherein the non-linear circuit element is configured to provide a steady state current to the column output line corresponding to characteristics of the non-linear circuit element,wherein the stored charge on the sense element is transferred through the non-linear circuit element to a feedback capacitor, and a reset switch is closed and the row select line is asserted high after reading an output voltage, wherein the output voltage is proportional to the feature of the input object.
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Accused Products
Abstract
Embodiments described herein include an input device including an array of sensing pixels configured to sense an input object in a sensing region, each of the sensing pixels including a sense element. Each of the sensing pixels also includes a first transistor, wherein the first transistor includes a gate terminal connected to a row select line and a second terminal connected to the sense element. Each of the sensing pixels also includes a non-linear circuit element, wherein the non-linear circuit element includes a first terminal connected to the sense element and the second terminal of the first transistor, and wherein the non-linear circuit element further includes a second terminal connected to a column output line.
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Citations
19 Claims
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1. An input device, comprising:
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an array of sensing pixels configured to sense an input object in a sensing region, each of the sensing pixels comprising; a sense element configured to store charge proportional to a feature of the input object; a first transistor comprising; a gate terminal connected to a row select line; and a second terminal connected to the sense element, wherein the first transistor is configured to; couple the sense element with an enable line in response to a high assertion of the row select line; and isolate the sense element from the row select line in response to a low assertion of the row select line; and a non-linear circuit element, wherein the non-linear circuit element comprises; a first non-linear circuit element terminal connected to the sense element and the second terminal of the first transistor; and a second non-linear circuit element terminal connected to a column output line, wherein the non-linear circuit element is configured to provide a steady state current to the column output line corresponding to characteristics of the non-linear circuit element, wherein the stored charge on the sense element is transferred through the non-linear circuit element to a feedback capacitor, and a reset switch is closed and the row select line is asserted high after reading an output voltage, wherein the output voltage is proportional to the feature of the input object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A processing system configured to operate an array of sensing pixels to capture an image of an input object, comprising:
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a readout circuit, wherein the readout circuit comprises a charge integrating amplifier circuit connected to a column output line and configured to; output a voltage representing the input object; and measure a current corresponding to characteristics of a non-linear circuit element; wherein driver circuitry is configured to; connect a sense element to an enable line through a first transistor by asserting a row select line high; isolate the sense element from the enable line by asserting the row select line; transfer a charge stored on the sense element through the non-linear circuit element to a feedback capacitor of the charge integrating amplifier circuit; and after readout of the voltage, assert the row select signal high and close a reset switch of the charge integrating amplifier circuit. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for operating an input device, comprising:
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asserting a row select line high to couple a sense element to an enable line through a first transistor, wherein the row select line is coupled to a gate terminal of the first transistor, and wherein a second terminal of the first transistor is coupled to the sense element; collecting a charge at the sense element, wherein the charge is proportional to a feature of an input object; asserting the row select line and the enable line low to isolate the sense element from the enable line and transfer the charge stored on the sense element to a feedback capacitor through a non-linear circuit element; reading an output voltage, wherein the output voltage is proportional to the feature of the input object; and
wherein the non-linear circuit element is configured to provide a steady state current corresponding to characteristics of the non-linear circuit element; andafter reading the output voltage, asserting the row select line high and closing a reset switch. - View Dependent Claims (17, 18, 19)
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Specification