Imaging active pixel device having a non-destructive read-out gate

• US 5,541,402 A
• Filed: 10/17/1994
• Issued: 07/30/1996
• Est. Priority Date: 10/17/1994
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Ackland, Bryan D., Dickinson, Alexander G., Inglis, David A., Eid, El-Sayed I.
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US08/323,945
• Time in Patent Office: 652 Days
• Field of Search: 250/208.1, 250/214 LA, 250/214 C, 250/214.1, 257/239, 257/225, 257/236, 257/231, 358/443, 358/445, 358/447, 358/448, 377/58, 377/117, 348/294, 348/297
• US Class Current: 250/208.1
• 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

Abstract

The imaging pixel according to the present invention includes a floating gate pixel node capable of nondestructive readout and active source follower output circuitry suitable for combination with other like imaging pixels to form an imaging array.

Claims

1. An imaging pixel having non-destructive read out, comprising:

a first charge collection device configured for collecting photo-charges at a level proportional to energy received from a portion of an object to be imaged;

a second charge collection device, being operatively connected to said first charge signal collection device and configured for selectively receiving and collecting said photo-charges from said first charge collection device; and

a gating device being operatively connected to said second charge collection device, for selectively reading the level of said photo-charges collected in said second charge collection device without destructing the collected photo-charges.

2. The imaging pixel device according to claim 1, further including means for selectively transferring said collected charges between said first and second charge collection devices.

3. The imaging pixel device according to claim 1, wherein said gating device includes transistors connected in a source follower format.

4. The imaging pixel device according to claim 1, wherein said gating device is further configured to commonly connect to at least one other gating device external to said imaging pixel for reading out from other imaging pixels disposed externally to said imaging pixel.

5. The imaging pixel device according to claim 1, further including a reverse-biased semiconductive junction, being operatively connected to at least one of said first and second charge signal collection devices, for selectively discharging said collected photo-charges.

6. The imaging pixel device according to claim 5, wherein said semiconductive junction is buried and vertically disposed adjacent to at least one of said first and second charge collection devices.

7. The imaging pixel device according to claim 6 wherein said buried semiconductive junction is formed from an n-type substrate with a p-type epitaxial layer.

8. The imaging pixel device according to claim 5, wherein said semiconductive junction is p-n type and is disposed horizontally adjacent said first charge collection device.

9. An imaging pixel device for imaging a portion of an object, comprising:

collection means for collecting energy reflected from said portion of said object;

storage means, operatively coupled to said collection means for storing said collected energy;

output means coupled to said storage means, for selectively reading a potential value corresponding to said collected energy and for buffering said storage means; and

transferring means for selectively transferring said collected energy between said collection means and said storage means without destructing said collected energy for repeat read-outs.

10. The imaging pixel device according to claim 9, where said transferring means includes two transistors which are commonly connected and control the amount of collected energy transferred from said collection means to said storage means.

11. The imaging pixel device according to claim 9, wherein said output means includes transistors connected in a source follower format.

12. The imaging pixel device according to claim 11, wherein said transistors are CMOS.

13. The imaging pixel device according to claim 9, further including means for discharging said collected energy.

14. The imaging pixel device according to claim 13, wherein said means for discharging includes a reverse-biased semiconductive junction.

15. A method for imaging from an imaging pixel device, comprising the steps of:

detecting energy reflected from an object to be imaged by a photo-detecting device;

generating photo-charges in an amount corresponding to said detected energy;

transferring said photo-charges to and from said photo-detecting device and a read-out storage device up to a plurality of times without destructing the photo-charges;

buffering said read-out storage device from an output gate; and

outputting from said output gate a potential value corresponding to the amount of photo-charges stored in said read-out storage device.

16. The method according to claim 15, further including the step of discharging said generated photo-charges with a reverse biased semiconductive junction.

17. The method according to claim 15, wherein said outputting step further includes the steps of:

comparing said potential to a predetermined potential criterion;

transferring said photo-charges to said photo-detecting device upon failure of said criterion;

further generating photo-charges;

transferring photo-charges collected in said photo-detecting device to said read-out storage device; and

outputting a potential corresponding to said photo-charges in said storage device.