Gate driver for a fingerprint sensor
View Patent ↗An example gate driver for an array of sensing pixels is disclosed. The gate driver includes a first flip-flop including a first data input and a first data output. The first data output is coupled to a first group of sensing pixels of the array. The gate driver also includes a second flip-flop including a second data input and a second data output. The second data output is coupled to a second group of sensing pixels of the array. The gate driver further includes a first insertion circuit configured to receive a first start signal and to cause, based on the first start signal, the second flip-flop to drive the second group of sensing pixels without the first flip-flop driving the first group of sensing pixels for a scan of the array.
1. A gate driver for an array of sensing pixels, the gate driver comprising:
a first flip-flop including a first data input and a first data output, wherein the first data output is coupled to a first group of sensing pixels of the array; a second flip-flop including a second data input and a second data output, wherein the second data output is coupled to a second group of sensing pixels of the array; and
a first insertion circuit configured to receive a first start signal and to cause, based on the first start signal, the second flip-flop to drive the second group of sensing pixels without the first flip-flop driving the first group of sensing pixels for a scan of the array,
wherein:
the first group of sensing pixels is a first column of sensing pixels in the array,
the second group of sensing pixels is a second column of sensing pixels subsequent to the first column of sensing pixels in the array,
the first insertion circuit is further configured to receive a first stop signal and to prevent, based on the first stop signal, the second flip-flop from driving the second column of sensing pixels after the first flip-flop drives the first column of sensing pixels, and
the first insertion circuit further includes a logical OR gate and a logical AND gate, wherein:
the logical OR gate is configured to perform an OR operation on the first start signal and the first data output from the first flip-flop and provide the result to the AND gate, and
the logical AND gate is configured to perform an AND operation on the result from the OR gate and the first reset signal and provide the result to the second data input of the second flip-flop.
2. The gate driver of claim 1 , wherein each flip-flop of the gate driver includes a RESET input to receive a reset signal to stop the scan.
3. The gate driver of claim 1 , further comprising:
a third flip-flop including a third data input and a third data output, wherein the third data output is coupled to a third column of sensing pixels of the array;
a fourth flip-flop including a fourth data input and a fourth data output, wherein the fourth data output is coupled to a fourth column of sensing pixels of the array; and
a second insertion circuit configured to receive a second start signal and a second stop signal, the second insertion circuit being configured to:
cause, based on the second start signal, the fourth flip-flop to drive the fourth column of sensing pixels without the third flip-flop driving the third column of sensing pixels; and
prevent, based on the second stop signal, the fourth flip-flop from driving the fourth column of sensing pixels after the third flip-flop drives the third column of sensing pixels.
4. The gate driver of claim 1 , further comprising:
a plurality of additional flip-flops in sequence, wherein the first flip-flop and the second flip-flop are in the sequence; and
a plurality of additional insertion circuitries, wherein an output of each of the plurality of additional insertion circuitries is coupled to a data input of a corresponding flip-flop of the plurality of additional flip-flops.
5. The gate driver of claim 4 , wherein the number of insertion circuits is less than the number of flip-flops in sequence in the gate driver.
6. The gate driver of claim 5 , wherein the array of sensing pixels is included in a fingerprint sensor.
7. A sensor, comprising:
an array of sensing pixels configured to sense a touch for a sensing region of the sensor;
a gate driver configured to drive a portion of the array of sensing pixels in performing a scan by the sensor, the gate driver including:
a first flip-flop including a first data input and a first data output, wherein the first data output is coupled to a first group of sensing pixels of the array; a second flip-flop including a second data input and a second data output, wherein the second data output is coupled to a second group of sensing pixels of the array; and
a first insertion circuit configured to receive a first start signal and to cause, based on the first start signal, the second flip-flop to drive the second group of sensing pixels without the first flip-flop driving the first group of sensing pixels for a scan of the array; and
a controller configured to control the gate driver to drive the portion of the array in performing the scan,
wherein:
the first group of sensing pixels is a first column of sensing pixels in the array,
the second group of sensing pixels is a second column of sensing pixels subsequent to the first column of sensing pixels in the array,
the first insertion circuit is further configured to receive a first stop signal and to prevent, based on the first stop signal, the second flip-flop from driving the second column of sensing pixels after the first flip-flop drives the first column of sensing pixels, and
the first insertion circuit further includes a logical OR gate and a logical AND gate, wherein:
the logical OR gate is configured to perform an OR operation on the first start signal and the first data output from the first flip-flop and provide the result to the AND gate, and
the logical AND gate is configured to perform an AND operation on the result from the OR gate and the first reset signal and provide the result to the second data input of the second flip-flop.
8. The sensor of claim 7 , wherein each flip-flop of the gate driver includes a RESET input to receive a reset signal to stop the scan.
9. The sensor of claim 7 , wherein the gate driver further includes:
a third flip-flop including a third data input and a third data output, wherein the third data output is coupled to a third column of sensing pixels of the array;
a fourth flip-flop including a fourth data input and a fourth data output, wherein the fourth data output is coupled to a fourth column of sensing pixels of the array; and
a second insertion circuit configured to receive a second start signal and a second stop signal, the second insertion circuitry being configured to:
cause, based on the second start signal, the fourth flip-flop to drive the fourth column of sensing pixels without the third flip-flop driving the third column of sensing pixels; and
prevent, based on the second stop signal, the fourth flip-flop from driving the fourth column of sensing pixels after the third flip-flop drives the third column of sensing pixels.
10. The sensor of claim 7 , wherein the sensor is a fingerprint sensor configured to scan multiple concurrent fingerprints during the scan.
11. The sensor of claim 10 , wherein the controller is configured to receive one or more indications from a proximity sensor, wherein:
each indication is a location of a touch sensed by the proximity sensor in a sensing region of the fingerprint sensor; and
one or more non-overlapping portions of the array to be driven for a fingerprint scan correspond to the one or more sensed touches, wherein each of the one or more non-overlapping portions includes a plurality of neighboring columns of sensing pixels in the array.