Imaging systems having image sensor pixel arrays with sub-pixel resolution capabilities

Patent metadata

Field	Value
Publication number	US-9888198-B2
Application number	US-201414295203-A
Country	US
Kind code	B2
Filing date	Jun 3, 2014
Priority date	Jun 3, 2014
Publication date	Feb 6, 2018
Grant date	Feb 6, 2018

Abstract

An image sensor may include an array of photodiodes and readout circuitry. A group of adjacent photodiodes in the array may be covered with a first color filter element that transmits a first color light and an additional group of adjacent photodiodes may be covered with a second color filter element that transmits a second color light. The group of photodiodes may share a floating diffusion node. The array may be operable in a low resolution mode in which the readout circuitry reads out image signals corresponding to a sum of charges generated by the group of photodiodes and in a high resolution mode in which the readout circuitry reads out image signals corresponding to charges generated by each of the photodiodes from the shared floating diffusion node. The photodiodes in the group may capture charge using different integration times for generating high-dynamic-range images.

First claim

What is claimed is:

1. An imaging system, comprising:
an array of photodiodes arranged in rows and columns, wherein the array comprises a first group of photodiodes and a second group of photodiodes, first and second consecutive rows, and first and second consecutive columns, wherein the first group of photodiodes comprises a first photodiode located in the first row and first column, a second photodiode located in the first row and second column, a third photodiode located in the second row and first column, and a fourth photodiode located in the second row and second column;
a first color filter element formed over the first group of photodiodes, wherein the first color filter element is configured to pass light of a first color to each photodiode of the first group;
a second color filter element formed over the second group of photodiodes, wherein the second color filter element is configured to pass light of a second color that is different than the first color to each photodiode of the second group;
a shared charge storage region coupled to the first group of photodiodes, wherein the first, second, third, and fourth photodiodes are coupled to the shared charge storage region through respective first, second, third, and fourth charge transfer gates;
an additional charge storage region coupled to the shared charge storage region through a dual gain conversion gate, wherein the dual gain conversion gate is directly coupled to the first transfer gate, the second transfer gate, and the shared charge storage region;
a first microlens formed directly over the first and second photodiodes, wherein the first and second photodiodes are configured to generate a first charge during a first integration time; and
a second microlens formed directly over the third and fourth photodiodes, wherein the third and fourth photodiodes are configured to generate a second charge during a second integration time that is different from the first integration time.

2. The imaging system defined in claim 1 , wherein the first charge transfer gate is configured to transfer a portion of the first charge from the first photodiode to the shared charge storage region and the second charge transfer gate is configured to transfer a portion of the second charge from the third photodiode to the shared charge storage region, the imaging system further comprising:
readout circuitry coupled to the array, wherein the readout circuitry is operable in a low resolution mode in which the readout circuitry reads out image signals corresponding to a sum of the portions of the first and second charges from the shared charge storage region and in a high resolution mode in which the readout circuitry reads out image signals corresponding to a given one of the portions of the first and second charges from the shared charge storage region.

3. The imaging system defined in claim 2 , further comprising:
control circuitry coupled to the array, wherein the control circuitry is configured to turn on the dual gain conversion gate when the readout circuitry is in the low resolution mode, and wherein the control circuitry is configured to turn off the dual gain conversion gate when the readout circuitry is in the high resolution mode.

4. The imaging system defined in claim 1 , further comprising:
four additional adjacent photodiodes in the array; and
four respective microlenses each formed directly over a respective one of the four additional adjacent photodiodes in the array.

5. The imaging system defined in claim 1 , further comprising:
four additional adjacent photodiodes in the array; and
a third microlens that is formed directly over all of the four additional adjacent photodiodes.

6. The imaging system defined in claim 1 , wherein the second group of photodiodes comprises fifth, sixth, seventh, and eighth photodiodes, wherein the fifth and sixth photodiodes are configured to generate a third charge during the second integration time, wherein the seventh and eighth photodiodes are configured to generate a fourth charge during the first integration time, wherein the fifth photodiode is located in the first row and a third column in the array, wherein the sixth photodiode is located in the second row and a fourth column in the array, wherein the seventh photodiode is located in the second row and the third column, wherein the eighth photodiode is located in the first row and fourth column, wherein the third column is adjacent to the second column, and wherein the fourth column is adjacent to the third column.

7. The imaging system defined in claim 6 , wherein the array further comprises:
a third group of photodiodes; and
a third color filter element formed over the third group of photodiodes, wherein the third color filter element is configured to pass light of the second color to each photodiode of the third group, wherein the third group of photodiodes comprises ninth, tenth, eleventh, and twelfth photodiodes, wherein the ninth and tenth photodiodes are configured to generate a fifth charge during the first integration time, wherein the eleventh and twelfth photodiodes are configured to generate a sixth charge during the second integration time, wherein the ninth photodiode is located in a third row and the third column of the array, wherein the tenth photodiode is located in a fourth row and the fourth column of the array, wherein the eleventh photodiode is located in the third row and the fourth column, wherein the twelfth photodiode is located in the fourth row and third column, wherein the third row is adjacent to the second row, and wherein the fourth row is adjacent to the third row.

8. The imaging system defined in claim 1 , wherein the first color filter element is configured to light selected from the group consisting of: red light, green light, and blue light.

9. The imaging system defined in claim 1 , wherein the second group of photodiodes is located in third and fourth consecutive rows and the first and second columns of the array, wherein the third row is adjacent to the second row, wherein the first group of photodiodes is configured to output first image signals over a first column output line, and wherein the second group of photodiodes is configured to simultaneously output second image signals over a second column output line that is different from the first column output line.

10. The imaging system defined in claim 1 , further comprising:
four additional adjacent photodiodes in the array;
a microlens formed directly over a first pair of the four additional adjacent photodiodes, wherein a second pair of the four additional adjacent photodiodes are formed without any corresponding microlenses.

11. A method of operating an imaging system having readout circuitry an array of photosensitive regions arranged in rows and columns, wherein the array comprises first, second, third, and fourth consecutive rows and first, second, third, and fourth consecutive columns of photosensitive regions, the method comprising:
with a first photosensitive region located in the first row and the first column and a second photosensitive region located in the first row and the third column, beginning charge integration at a first time;
with a third photosensitive region located in the first row and the second column and a fourth photosensitive region located in the first row and the fourth column, beginning charge integration at a second time, wherein the second time is different from the first time;
with a fifth photosensitive region located in the second row and first column, beginning charge integration at a third time, wherein the third time is different from the first and second times;
with a sixth photosensitive region located in the

Assignees

• Semiconductor Components Ind Llc

Inventors

• Mauritzson Richard A
• Engelbrecht Dennis Robert
• Black Robert A

Classifications

• H04N25/134 Primary

  based on three different wavelength filter elements · CPC title

• H04N25/771

  comprising storage means other than floating diffusion · CPC title

• H04N25/778

  comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself · CPC title

• H04N25/76

  Addressed sensors, e.g. MOS or CMOS sensors · CPC title

• H04N25/70

  SSIS architectures; Circuits associated therewith · CPC title