Variable pixel clock electronic shutter control

• US 7,804,536 B2
• Filed: 04/06/2009
• Issued: 09/28/2010
• Est. Priority Date: 07/20/2001
• Status: Expired due to Term

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: Blerkom, Daniel Van
• Primary Examiner(s): Chan; Jason
• Assistant Examiner(s): Giles; Nicholas G
• Application Number:
  US12/418,802
• Publication Number:
  US 20090201407A1
• Time in Patent Office: 540 Days
• Field of Search: 348/296, 348/294, 348/207.99, 348/302, 348/308, 348/229.1, 348/230.1, 348/297, 348/298, 250/208.1
• US Class Current: 348/296
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS
• CPC Class Codes: H04N 25/745 Circuitry for generating timing or clock signals
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

CMOS image sensor with a rolling shutter that uses two separate clocks. One of the clocks is used during normal operation. When timing is changed, the other clock is started and used during an interim period to avoid distortion in the image. After that interim period, the new clock timing is coupled to the original clock circuit.

Claims

1. A controller for producing a rolling shutter to control an image sensor, the controller comprising:

a row read module, operating in accordance with a first clock speed, the row read module for producing first signals to control an integration beginning of the image sensor, second signals to control an integration ending of the image sensor, and third signals when a pixel clock speed change is required; and

a row read jumping module, operating in accordance with a second different clock speed, the row read jumping module connected to receive the third signals and for outputting to the row read module fourth signals to control the integration beginning of the image sensor in accordance with the second clock speed.

2. The controller of claim 1, wherein during normal operation the rolling shutter is produced such that integration ending for a current row is synchronized with integration beginning of a next row.

3. The controller of claim 2, wherein during normal operation the row read module produces the second signal for a new row at a same time the row read module produces the first signal for a current row.

4. The controller of claim 1, wherein the row read and row read jumping modules are implemented using a programmed processor.

5. The controller of claim 1, wherein the third signal is generated when a readout pointer reaches a top of a current frame plus an offset.

6. The controller of claim 1, wherein the row read jumping module is disabled once integration beginning in accordance with the second clock speed begins.

7. A controller for producing a rolling shutter to control an image sensor, the controller comprising:

a first module for producing the rolling shutter and outputting first clock signals to control the image sensor; and

a second module in communication with the first module, said second module for producing a second clock signal during a time when the rolling shutter is being changed from a first characteristic to a second characteristic, and outputting the second clock signal at a same time as the first clock signals during an interim frame period,

wherein the first module thereafter uses the second clock signal to produce a new rolling shutter at a rate associated with said second clock signal.

8. The controller of claim 7, wherein the first module activates the second module in response to a request to change the rolling shutter from the first characteristic to the second characteristic.

9. The controller of claim 7, wherein the first module produces the rolling shutter such that an integration time starting signal for a current row in the image sensor is synchronized with an integration time ending signal for a different row in the image sensor.

10. The controller of claim 7, wherein the second module produces signals which cause the integration time starting signal for a current row in the image sensor to be synchronized with a different integration time ending signal for a different row in the image sensor.

11. The controller of claim 10, wherein the rolling shutter includes a readout pointer and a shutter pointer, with a start of each row readout time being established by the shutter pointer.

12. The controller of claim 11, wherein the shutter pointer resets values within a specified row of the image sensor.

13. The controller of claim 7, wherein the first clock signals and the second clock signals operate at different clock speeds.

14. An image sensor comprising:

an array of image sensing elements; and

a controller connected to the array and for producing a rolling shutter to control the image sensing elements, the controller comprising;

a row read module, operating in accordance with a first clock speed, the row read module for producing first signals to control an integration beginning of the image sensor, second signals to control an integration ending of the image sensor, and third signals when a pixel clock speed change is required; and

a row read jumping module, operating in accordance with a second different clock speed, the row read jumping module connected to receive the third signals and for outputting to the row read module fourth signals to control the integration beginning of the image sensor in accordance with the second clock speed.

15. The image sensor of claim 14, wherein during normal operation the rolling shutter is produced such that integration ending for a current row is synchronized with integration beginning of a next row.

16. The image sensor of claim 15, wherein during normal operation the row read module produces the second signal for a new row at a same time the row read module produces the first signal for a current row.

17. The image sensor of claim 14, wherein the third signal is generated when a readout pointer reaches a top of a current frame plus an offset.

18. The image sensor of claim 14, wherein the row read jumping module is disabled once integration beginning of the image sensor in accordance with the second clock speed begins.