Image sensor with high dynamic range linear output

• US 7,190,398 B1
• Filed: 09/05/2000
• Issued: 03/13/2007
• Est. Priority Date: 11/07/1995
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Fossum, Eric R., Yadid-Pecht, Orly
• Primary Examiner(s): Ometz; David
• Assistant Examiner(s): NGUYEN, LUONG TRUNG
• Application Number:
  US09/654,922
• Time in Patent Office: 2,380 Days
• Field of Search: 348/294, 348/297, 348/300, 348/308
• US Class Current: 348/308
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 25/533 by using differing integration times for different sensor regions
• CPC Class Codes: H04N 25/587 acquired sequentially, e.g. using the combination of odd and even image fields
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/767 Horizontal readout lines, multiplexers or registers
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

Designs and operational methods to increase the dynamic range of image sensors and APS devices in particular by achieving more than one integration times for each pixel thereof. An APS system with more than one column-parallel signal chains for readout are described for maintaining a high frame rate in readout. Each active pixel is sampled for multiple times during a single frame readout, thus resulting in multiple integration times. The operation methods can also be used to obtain multiple integration times for each pixel with an APS design having a single column-parallel signal chain for readout. Furthermore, analog-to-digital conversion of high speed and high resolution can be implemented.

Claims

1. A method, comprising:

forming a two-dimensional array of pixels;

allowing the pixels to receive light representing an image to be detected by allowing the pixels to accumulate light beginning at a first time;

in each frame readout, reading out each of the pixels at least at both of a first shorter integration time, which begins at said first time, and ends at a second time and a second longer integration time, which begins at said first time and ends at a third time subsequent to said second time; and

resetting each pixel after each readout of the pixel.

2. A method, comprising:

forming a two-dimensional array of pixels;

allowing the pixels to receive light representing an image to be detected by allowing the pixels to accumulate light beginning at a first time;

in each frame readout, reading out each of the pixels at least at both of a first shorter integration time, which begins at said first time, and ends at a second time and a second longer integration time, which begins at said first time and ends at a third time subsequent to said second time;

resetting each pixel after each readout of the pixel; and

processing information from the readouts to combine portions of information from the first shorter integration time with information from the readouts from the second longer integration time, to form a composite readout.

3. A method comprising:

forming a two-dimensional array of pixels;

allowing the pixels to receive light representing an image to be detected by allowing the pixels to accumulate light beginning at a first time;

in each frame readout, reading out each of the pixels at least at both of a first shorter integration time, which begins at said first time, and ends at a second time and a second longer integration time, which begins at said first time and ends at a third time subsequent to said second time wherein said reading out comprises reading out first row of pixels representing said first shorter integration time and a second row of pixels representing said second longer integration time; and

resetting each pixel after each readout of the pixel.

4. A method as in claim 3, wherein said reading out comprises reading out the pixels into a first buffer representing the shorter integration time, and reading out the pixels into a second buffer representing the longer integration time.

5. A method as in claim 3, wherein the pixels are non-destructively read out, and said reading out comprises reading out the pixels first at said shorter integration time and second at said longer integration time.

6. A method as in claim 3, wherein said reading out comprises reading out the pixels from the shorter integration time into the same buffer.

7. A method as in claim 3, further comprising reading out a third row of the pixels representing information at a third integration time.

8. A method as in claim 3, wherein said pixels are active pixels.

9. A method, comprising:

allowing an array of pixels to receive light representing an image to be detected;

reading two separated rows of pixels in each single row readout process to produce two different readout signals with different integration times for each pixel in a single frame readout wherein said reading reads an entire row at each reading time; and

resetting each pixel after each readout of the pixel.

13. A method as in claim 9, further comprising increasing a dynamic range of information obtained from a pixel by combining information from a first pixel with a first integration time and information from said first pixel with a second integration time.

14. A method as in claim 9, further comprising reading a third row of pixels during each single row readout process.

10. A method, comprising:

allowing an array of pixels to receive light representing an image to be detected;

in each frame readout, reading two separated rows of pixels in each single row readout process, wherein said two separated rows of pixels represent a first row of pixels representing the image integration for a shorter integration time, and a second row of pixels representing the image integration for a longer integration time and

resetting each pixel after each readout of the pixel.

11. A method as in claim 10, wherein said reading comprises non-destructively reading.

12. A method as in claim 10, wherein said reading comprises destructively reading.

15. A method as in claim 12, further comprising carrying out correlated double sampling as part of said reading.

16. A method as in claim 10, wherein said reading comprises reading of each of said rows to a separate storage area.

17. A method as in claim 10, wherein said pixels are active pixels.

18. A system, comprising:

a semiconductor substrate defining a two-dimensional array of pixels, each of said pixels formed with a photoreceptor portion therein, and at least one active readout portion therein,

a readout control part, controlling said pixels to allow the pixels to receive light representing an image to be detected, and allowing the pixels to accumulate light for an integration, and to control the pixels to readout information, within each frame readout, from the pixels representative of light reception for a first integration time starting at a first time, and a second integration time longer than said first integration time also starting at said first time, such that each pixel provides light output integrated over both of said first and second integration times for each pixel within each frame readout, wherein the readout control part is configured to reset each pixel after each readout of the pixel.

19. A system as in claim 18, wherein said readout control part also controls said pixels to accumulate light for a third integration time.

20. A system as in claim 18, further comprising an image information combiner, which combines information from the first shorter integration time with information from the second longer integration time, to produce composite information about the image.

21. A system as in claim 18, further comprising a first buffer, on the semiconductor substrate, receiving information indicative of the light integrated for said first integration time, and a second buffer, receiving information indicative of the light integrated for the second integration time.

22. A system as in claim 18, further comprising a buffer receiving information indicative of the light reception for the first integration time and indicative of the light reception for the second integration time.