IMAGE SENSOR

• US 20200137339A1
• Filed: 10/23/2019
• Published: 04/30/2020
• Est. Priority Date: 10/24/2018
• Status: Abandoned Application

• Current Assignee: Guangzhou Tyrafos Semiconductor Technologies Co., Ltd.
• Original Assignee: Guangzhou Tyrafos Semiconductor Technologies Co., Ltd.
• Inventors: Yin, Ping-Hung, Wang, Jia-Shyang
• Application Number:
  US16/660,816
• Publication Number:
  US 20200137339A1
• Time in Patent Office: Days
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/633 by using optical black pixels
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion
• CPC Class Codes: H04N 25/78 Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters

Abstract

An image sensor including a signal processor and a pixel array is provided. The pixel array includes a plurality of active pixel units and a plurality of reference pixel units. The active pixel units are coupled to the signal processor. The active pixel units are configured to receive an image light signal during an image sensing period to output a plurality of sensing signals. The reference pixel units are coupled to the signal processor. The reference pixel units are masked and do not receive the image light signal during the image sensing period, so as to output a plurality of reference signals. The signal processor is configured to receive the sensing signals and the reference signals. The signal processor performs signal subtraction on the sensing signals and the reference signals to correspondingly generate a plurality of pixel data.

Claims

1. An image sensor, comprising:

a signal processor; and

a pixel array, comprising;

a plurality of active pixel units, coupled to the signal processor and configured to receive an image light signal during an image sensing period to output a plurality of sensing signals; and

a plurality of reference pixel units, coupled to the signal processor, the reference pixel units being masked and not receiving the image light signal during the image sensing period, so as to output a plurality of reference signals, wherein the active pixel units and the reference pixel units are positioned in a same row, and the signal processor is configured to receive the sensing signals and the reference signals and perform subtraction on the sensing signals and the reference signals to correspondingly generate a plurality of pixel data.

2. The image sensor according to claim 1, wherein the image sensor further comprises a serial peripheral interface coupled to the signal processor, and the signal processor further comprises:

a readout circuit, coupled to the active pixel units and the reference pixel units and configured to simultaneously read out the sensing signals and the reference signals at a data readout time point; and

a correction circuit, coupled to the readout circuit and the serial peripheral interface and configured to receive the sensing signals and the reference signals, wherein the correction circuit performs subtraction on the sensing signals and the reference signals to output the pixel data to the serial peripheral interface.

3. The image sensor according to claim 2, wherein the image sensor determines, according to a data transmission request of the serial peripheral interface, whether to read out the sensing signals of the active pixel units and the reference signals of the reference pixel units in one of a plurality of columns of the pixel array.

4. The image sensor according to claim 1, wherein the active pixel units and the reference pixel units each at least comprise:

a first switch, wherein a first terminal of the first switch is coupled to a reference voltage;

a photodiode, wherein a first terminal of the photodiode is coupled to a second terminal of the first switch, and a second terminal of the photodiode is grounded;

a second switch, wherein a first terminal of the second switch is coupled to the second terminal of the first switch and the first terminal of the photodiode;

at least one charge storage component, wherein a first terminal of the charge storage component is coupled to a second terminal of the second switch, and a second terminal of the at least one charge storage component is grounded;

a third switch, wherein a first terminal of the third switch is coupled to the second terminal of the second switch and the first terminal of the at least one charge storage component, and a second terminal of the third switch is coupled to a floating diffusion node;

a fourth switch, wherein a first terminal of the fourth switch is coupled to the reference voltage, and a second terminal of the fourth switch is coupled to the floating diffusion node; and

a fifth switch, wherein a first terminal of the fifth switch is coupled to the reference voltage, a control terminal of the fifth switch is coupled to the floating diffusion node, a second terminal of the fifth switch is coupled to a data output terminal, and the data output terminal is coupled to the signal processor.

5. The image sensor according to claim 4, wherein the respective photodiodes of the active pixel units sense the image light signal during the image sensing period, and the respective photodiodes of the active pixel units output the sensing signals to the respective charge storage components of the active pixel units at a data storage time point to enable the respective charge storage components of the active pixel units to store the sensing signals,

wherein the respective photodiodes of the reference pixel units do not sense the image light signal during the image sensing period, and the respective photodiodes of the reference pixel units output the reference signals to the respective charge storage components of the reference pixel units at the data storage time point to enable the respective charge storage components of the reference pixel units to store the reference signals.

6. The image sensor according to claim 5, wherein the respective charge storage components of the active pixel units and the respective charge storage components of the reference pixel units comprise a same leakage current.

7. The image sensor according to claim 5, wherein the respective third switches and the respective fourth switches of the active pixel units and the respective third switches and the respective fourth switches of the reference pixel units are simultaneously turned on at a data readout time point, so that the signal processor simultaneously reads out the sensing signals and the reference signals of the respective charge storage components through the second terminals of the respective fifth switches of the active pixel units and the second terminals of the respective fifth switches of the reference pixel units.

8. The image sensor according to claim 1, wherein the pixel array performs a global shutter operation during the image sensing period to simultaneously expose each of the active pixel units of the pixel array.

9. The image sensor according to claim 1, wherein the pixel array performs a rolling shutter operation during the image sensing period to simultaneously expose the active pixel units in each column of the pixel array, and the columns of the pixel array are sequentially exposed.

10. The image sensor according to claim 1, wherein the image sensor is a fingerprint sensor.