Image sensor having pixels with different integration periods

• US 9,596,420 B2
• Filed: 12/05/2013
• Issued: 03/14/2017
• Est. Priority Date: 12/05/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Fan, Xiaofeng, Lee, Chiajen, Malone, Michael R., Sharma, Anup K.
• Primary Examiner(s): Vieaux, Gary C
• Application Number:
  US14/098,504
• Publication Number:
  US 20150163422A1
• Time in Patent Office: 1,195 Days
• US Class Current: 1/1
• CPC Class Codes: H04N 25/533 by using differing integration times for different sensor regions
• CPC Class Codes: H04N 25/583 with different integration times

Abstract

An image sensor includes pixels that accumulate charge during a first integration period and pixels that accumulate charge during shorter second integration periods when an image is captured. The pixels having the shorter second integration period accumulate charge at two or more different times during the first integration period. Charge is read out of the pixels associated with the first integration period at the end of the first integration period, while charge is read out of the pixels having the second integration period at the end of each second integration period.

Claims

1. An imaging system, comprising:

an image sensor having a plurality of pixels, wherein

a first portion of the pixels accumulate charge for a first integration period; and

a second portion of the pixels accumulate charge for a shorter second integration period, wherein the second portion of the pixels having the shorter second integration period accumulate charge two or more times during the first integration period;

readout circuitry operatively connected to the plurality of pixels;

a storage device operatively connected to the readout circuitry; and

a processor operatively connected to the readout circuitry and to the storage device, wherein the processor is configured to;

at an end of at least one second integration time, enable the readout circuitry to read first pixel data from each pixel in the second portion of the pixels;

store the first pixel data in the storage device;

at an end of the first integration period, enable the readout circuitry to read second pixel data from each pixel in the second portion of the pixels and read out third pixel data from each pixel in the first portion of the pixels; and

combine the first, the second, and the third pixel data to produce an image.

2. The imaging system as in claim 1, wherein the processor is adapted to adjust which pixels are associated with the first and second integration periods.

3. The imaging system as in claim 1, wherein the processor is adapted to determine an amount of time for each second integration period.

4. A method for capturing an image, the method comprising:

beginning a first integration period for a first portion of pixels in an image sensor;

beginning a second integration period for a second portion of pixels in the image sensor, wherein the second integration period is shorter than the first integration period;

reading out first pixel data from the pixels in the second portion of the pixels during the first integration period at the end of the second integration period;

storing the first pixel data;

beginning another second integration period for the second portion of the pixels;

reading out second pixel data from the pixels in the second portion of the pixels at the end of the first integration period;

reading out third pixel data from the pixels in the first portion of the pixels at the end of the first integration period; and

combining the first, the second, and the third pixel data to produce the image.

5. The method as in claim 4, wherein the second integration periods include substantially a same amount of time.

6. The method as in claim 4, wherein an amount of time in one second integration period differs from an amount of time in another second integration period.

7. The method as in claim 4, further comprising changing which pixels are associated with the first and second integration periods.

8. A method for capturing an image, the method comprising:

beginning a first integration period for a first plurality of pixels in an image sensor;

during the first integration period, beginning a plurality of second integration periods for a second plurality of pixels in the image sensor, wherein each second integration period is shorter than the first integration period and each second integration period begins at a distinct time within the first integration period;

at the end of each second integration period, reading out first pixel data from each pixel in the second plurality of pixels;

at the end of the first integration period, reading out second pixel data from each pixel in the first plurality of pixels and from each pixel in the second plurality of pixels; and

combining the first and the second pixel data to produce the image.

9. The method as in claim 8, wherein the second integration periods include is substantially a same amount of time.

10. The method as in claim 8, wherein an amount of time in one second integration period differs from an amount of time in another second integration period.

11. The method as in claim 8, further comprising prior to beginning the plurality of second integration periods, determining timing for the plurality of second integration periods.

12. The method as in claim 11, wherein determining timing for the plurality of second integration periods comprises:

capturing one or more test images; and

analyzing at least one test image to determining timing for the plurality of second integration periods.

13. The method as in claim 12, further comprising:

capturing N images, where N is an integer equal to or greater than one;

determining whether the timing for the plurality of second integration periods is to change after the N images have been captured; and

when the timing changes, changing the timing for at least one second integration period in the plurality of second integration periods.

14. The method as in claim 8, further comprising changing which pixels are associated with the first and second integration periods.

15. The method as in claim 8, further comprising storing the first signals read from the pixels in the second plurality of pixels.