Method and apparatus providing pixel storage gate charge sensing for electronic stabilization in imagers

• US 7,965,330 B2
• Filed: 10/29/2009
• Issued: 06/21/2011
• Est. Priority Date: 01/13/2006
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Panicacci, Roger
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US12/608,072
• Publication Number:
  US 20100045805A1
• Time in Patent Office: 600 Days
• Field of Search: 348/308, 348/250.1
• US Class Current: 348/308
• CPC Class Codes: H04N 25/40 Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion
• CPC Class Codes: H04N 3/155 Control of the image-sensor operation, e.g. image processing within the image-sensor

Abstract

An imaging device that stores charge from a photosensor under at least one storage gate. A driver used to operate the at least one storage gate, senses how much charge was transferred to the storage gate. The sensed charge is used to obtain at least one signature of the image scene. The at least one signature may then be used for processing such as e.g., motion detection, auto-exposure, and auto-white balancing.

Claims

1. An imaging device comprising:

a plurality of pixels, each pixel comprising a photosensor and at least a first gate for storing charge from the photosensor when activated by a first control signal;

a plurality of first driver and sense circuits, each first driver and sense circuit being connected to and associated with a respective first set of pixels, each first driver and sense circuit for generating the first control signal on a first control line connected to all pixels in its respective first set, each first driver and sense circuit for sensing via the first control line an amount of charge stored under the first gates in the respective first set;

a buffer memory, at least a first portion of the buffer memory for storing first digitized values of the sensed charge from the first gates for a first image frame, and at least a second portion of the buffer memory for storing second digitized values of the sensed charge from the first gates for a second image frame; and

means for detecting motion of at least one object in the first and second image frames using the stored first and second digitized values.

2. The imaging device of claim 1, wherein the means for detecting motion detects an amount and direction of motion for the at least one object.

3. The imaging device of claim 1, wherein the means for detecting motion detects an amount and direction of motion for the at least one object by computing differences between the stored first and second digitized values.

4. The imaging device of claim 1, wherein each pixel further comprises a second gate for storing charge from the photosensor when activated by a second control signal, and the device further comprises a plurality of second driver and sense circuits, each second driver and sense circuit being connected to and associated with a respective one of the first set of pixels, each second driver and sense circuit generating the second control signal for all pixels in its respective set and sensing an amount of charge stored under the second gates in the respective set, and

wherein a third portion of the buffer memory further stores third digitized values of the sensed charge from the second gates for the first image frame, and a fourth portion of the buffer memory stores fourth digitized values of the sensed charge from the second gates for the second image frame and the means for detecting motion uses the stored first, second, third and fourth digitized values to detect motion of the at least one object.

5. The imaging device of claim 4, wherein a portion of said pixels further comprises a third gate for storing charge from said photosensor when activated by a third control signal and the device further comprises a plurality of third driver and sense circuits, each third driver and sense circuit being connected to and associated with a respective third gate, each third driver and sense circuit generating the third control signal for its respective third gate and sensing an amount of charge stored under the third gate, and

wherein a fifth portion of the buffer memory further stores fifth digitized values of the sensed charge from the third gates for the first image frame, and a sixth portion of the buffer memory stores sixth digitized values of the sensed charge from the third gates for the second image frame and the means for detecting motion uses the stored first, second, third, fourth, fifth and sixth digitized values to detect motion of the at least one object.

6. The imaging device of claim 5, wherein said third gates are organized as a diagonal pattern across said array.

7. The imaging device of claim 4, wherein the plurality of pixels are organized into an array of rows and columns, and each first set of pixels corresponds to a respective row of pixels and each second set of pixels corresponds to a respective column of pixels.

8. The imaging device of claim 1, wherein said first gate is a transfer gate and said first control signal is a transfer gate control signal.

9. A method of operating an imaging device, the imaging device comprising a plurality of pixels, each comprising a photosensor and at least a first storage gate, said method comprising the acts of:

for each pixel, storing first charge from the photosensor under the first storage gate by placing a first control signal on a first control line;

for each pixel, sensing via the first control line the first charge stored under the first storage gate;

using the sensed first charges to obtain a first signature of a first image scene obtained by the imaging device,

for each pixel, storing second charge from the photosensor under the first storage gate by placing the first control signal on the first control line;

for each pixel, sensing via the first control line the second charge stored under the first storage gate;

using the sensed second charges to obtain a second signature of a second image scene obtained by the imaging device; and

detecting motion of at least one object in the first and second image scenes using the first and second signatures.

10. The method of claim 9, wherein the detecting step detects an amount and direction of motion for the at least one object.

11. The method of claim 9, wherein the detecting step detects an amount and direction of motion for the at least one object by computing differences between the first and second signatures.

12. The method of claim 9, further comprising the act of using the first and second signatures of the first and second scenes to perform motion estimation.

13. The method of claim 9, wherein each pixel comprises a second storage gate and said method further comprises the acts of:

for each pixel, storing third charge from the photosensor under the second storage gate;

for each pixel, sensing the third charge stored under the second storage gate;

using the sensed third charge to obtain a third signature of the first image scene obtained by the imaging device;

for each pixel, storing fourth charge from the photosensor under the second storage gate;

for each pixel, sensing the fourth charge stored under the second storage gate;

using the sensed fourth charge to obtain a fourth signature of the second image scene obtained by the imaging device; and

detecting motion of the at least one object using the first, second, third and fourth signatures.

14. The method of claim 13, wherein a portion of the pixels comprises a third storage gate and said method further comprises the acts of:

for each pixel comprising the third storage gate, storing fifth charge from the photosensor under the third storage gate;

for each pixel comprising the third storage gate, sensing the fifth charge stored under the third storage gate;

using the sensed fifth charge to obtain a fifth signature of the first image scene;

for each pixel comprising the third storage gate, storing sixth charge from the photosensor under the third storage gate;

for each pixel comprising the third storage gate, sensing the sixth charge stored under the third storage gate;

using the sensed sixth charge to obtain a sixth signature of the first image scene; and

detecting motion of the at least one object using the first, second, third, fourth, fifth and sixth signatures.