Charge summing in an image sensor

• US 9,596,423 B1
• Filed: 09/30/2014
• Issued: 03/14/2017
• Est. Priority Date: 11/21/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Molgaard, Claus
• Primary Examiner(s): Selby, Gevell
• Application Number:
  US14/503,322
• Time in Patent Office: 896 Days
• Field of Search: 348/308
• US Class Current: 1/1
• CPC Class Codes: H04N 2209/045 using mosaic colour filter
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/713 Transfer or readout registers; Split readout registers or multiple readout registers

Abstract

An image sensor includes a pixel array having a plurality of pixels. Pixels can be summed or binned diagonally in the pixel array in a first diagonal direction and in a different second diagonal direction. The locations of the first and second diagonal summed pairs can be distributed across the pixel array.

Claims

1. A method for summing charge in an image sensor having a pixel array that includes plurality of pixels, the method comprising:

summing charge in pixels along a first diagonal direction to produce two or more first diagonal summed pairs, wherein the charge in each pixel is associated with a first color and the charge in the two or more first diagonal summed pairs is associated with the first color;

summing charge in pixels along a different second diagonal direction to produce two or more second diagonal summed pairs, wherein the charge in each pixel is associated with the first color and the charge in the two or more second diagonal summed pairs is associated with the first color;

summing charge in pixels along one or more non-diagonal directions to produce two or more summed pairs, wherein the charge in each pixel is associated with a second color and the charge in the two or more summed pairs is associated with the second color;

reading the two or more first diagonal summed pairs, the two or more second diagonal summed pairs, and the two or more summed pairs out of the pixel array;

summing together one first diagonal summed pair associated with the first color and another first diagonal summed pair associated with the first color;

summing together one second diagonal summed pair associated with the first color and another second diagonal summed pair associated with the first color; and

summing together one summed pair associated with the second color and another summed pair associated with the second color.

2. The method as in claim 1, wherein locations of the first and second diagonal summed pairs are distributed across the pixel array.

3. The method as in claim 1, wherein summing charge in pixels along a first diagonal direction comprises summing charge in two pixels in adjacent positions along a first diagonal direction.

4. The method as in claim 3, wherein summing charge in two pixels in adjacent positions along a first diagonal direction comprises summing charge in two pixels in adjacent rows along a first diagonal direction.

5. The method as in claim 1, wherein summing charge in pixels along a different second diagonal direction comprises summing charge in two pixels in adjacent positions along a different second diagonal direction.

6. The method as in claim 5, wherein summing charge in two pixels in adjacent positions along a different second diagonal direction comprises summing charge in two pixels in adjacent rows along a different second diagonal direction.

7. The method as in claim 1, wherein summing charge in pixels along one or more non-diagonal directions comprises summing charge in two pixels along a vertical direction.

8. The method as in claim 1, wherein:

the one first diagonal summed pair and the other first diagonal summed pair are summed together in a digital domain; and

the one second diagonal summed pair and the other second diagonal summed pair are summed together in the digital domain.

9. The method as in claim 1, wherein:

the one first diagonal summed pair and the other first diagonal summed pair are summed together in a voltage domain; and

the one second diagonal summed pair and the other second diagonal summed pair are summed together in the voltage domain.

10. The method as in claim 1, wherein the first and second diagonal directions alternate for every N diagonal summed pairs, where N is an integer greater than zero.

11. The method as in claim 1, further comprising:

summing charge in pixels along one or more non-diagonal directions to produce two or more summed pairs, wherein the charge in each pixel is associated with a third color and the charge in the two or more summed pairs is associated with the third color;

reading the two or more summed pairs out of the pixel array; and

summing together one summed pair associated with the third color and another summed pair associated with the third color.

12. An electronic device, comprising:

an image sensor including a plurality of pixels;

readout circuitry operatively connected to the pixel array; and

a processor operatively connected to the readout circuitry and to the image sensor, wherein the processor is adapted to produce timing signals that are received by the image sensor to;

sum charge in pixels associated with a first color along a first diagonal direction to produce two or more first diagonal summed pairs having charge associated with the first color;

sum charge in pixels associated with a second color along a different second diagonal direction to produce two or more second diagonal summed pairs having charge associated with the second color;

sum charge in pixels associated with a third color along one or more non-diagonal directions to produce two or more first summed pairs having charge associated with the third color; and

sum charge in pixels associated with a fourth color along one or more non-diagonal directions to produce two or more second summed pairs having charge associated with the fourth color.

13. The electronic device as in claim 12, wherein the processor is further adapted to produce timing signals that are received by the readout circuitry to sum first diagonal summed pairs together after the two or more first diagonal summed pairs are read out of the pixel array and to sum second diagonal summed pairs together after the two or more second diagonal summed pairs are read out of the pixel array.

14. The electronic device as in claim 12, wherein the processor is further adapted to produce timing signals that are received by the readout circuitry to sum first summed pairs together after the two or more first summed pairs are readout of the pixel array and to sum second summed pairs together after the two or more second summed pairs are readout of the pixel array.

15. The electronic device as in claim 12, wherein the first color and the second color comprise a same color.

16. A method for summing charge in an image sensor having a pixel array that includes plurality of pixels, the method comprising:

summing charge in a first portion of the pixels in the pixel array that are positioned in adjacent rows or columns along a first diagonal direction to produce two or more first diagonal summed pairs, wherein the charge in each pixel is associated with a first color and the charge in each first diagonal summed pair is associated with the first color;

changing a direction of summing to a different second diagonal direction;

summing charge in a second portion of the pixels in the pixel array that are positioned in adjacent rows or columns along the second diagonal direction to produce two or more second diagonal summed pairs, wherein the charge in each pixel is associated with a second color and the charge in each second diagonal summed pair is associated with the second color;

summing charge in a third portion of the pixels in the pixel array along one or more non-diagonal directions to produce two or more first summed pairs, wherein the charge in each pixel is associated with a third color and the charge in each summed pair is associated with the third color; and

summing charge in a fourth portion of the pixels in the pixel array along one or more non-diagonal directions to produce two or more second summed pairs, wherein the charge in each pixel is associated with a fourth color and the charge in each summed pair is associated with the fourth color;

summing at least two first diagonal summed pairs associated with the first color together;

summing at least two second diagonal summed pairs associated with the second color together;

summing at least two first summed pairs associated with the third color together; and

summing at least two second summed pairs associated with the fourth color together.

17. The method as in claim 16, further comprising:

prior to summing the at least two first diagonal summed pairs together, reading the at least two first diagonal summed pairs out of the pixel array;

prior to summing the at least two second diagonal summed pairs together, reading the at least two second diagonal summed pairs out of the pixel array;

prior to summing the at least two first summed pairs together, reading the at least two first summed pairs out of the pixel array; and

prior to summing the at least two second summed pairs together, reading the at least two second summed pairs out of the pixel array.

18. The method as in claim 16, wherein summing charge in pixels in the pixel array along one or more non-diagonal directions comprises summing charge in two pixels along a vertical direction.

19. The method as in claim 17, wherein the at least two first diagonal summed pairs are summed together in a digital domain, the at least two second diagonal summed pairs are summed together in the digital domain, the at least two first summed pairs are summed together in the digital domain, and the at least two second summed pairs are summed together in the digital domain.

20. The method as in claim 16, wherein the at least two first diagonal summed pairs are summed together in a voltage domain, the at least two second diagonal summed pairs are summed together in the voltage domain, the at least two first summed pairs are summed together in the voltage domain, and the at least two second summed pairs are summed together in the voltage domain.

21. The method as in claim 19, wherein the first color and the second color comprise a same color.