CMOS/CCD line transfer imager with low dark current

• US 6,433,326 B1
• Filed: 07/12/2000
• Issued: 08/13/2002
• Est. Priority Date: 07/14/1999
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Levine, Peter Alan, Tower, John Robertson, McCaffrey, Nathaniel Joseph, Pantuso, Francis Paul
• Primary Examiner(s): ALLEN, STEPHONE B
• Application Number:
  US09/614,765
• Time in Patent Office: 762 Days
• Field of Search: 250/208.1, 250/214.1, 250/214.R, 250/214.C, 348/272, 348/281, 348/282, 348/297, 348/298, 348/302, 348/303, 348/304, 348/305, 348/306, 348/308, 348/311, 348/312, 348/313, 348/314, 348/316, 348/317, 348/318, 348/319, 257/290, 257/291, 257/292, 438/57, 438/60, 438/73, 438/75
• US Class Current: 250/208.1
• CPC Class Codes: H01L 27/14881 of the hybrid type
• CPC Class Codes: H04N 25/20 for transforming only infrared radiation into image signals
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/713 Transfer or readout registers; Split readout registers or multiple readout registers
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A method and apparatus for low light imaging in which a plurality of relatively small detectors forming a line is coupled to a respective cell of a CCD register. A charge indicative of detected image information is provided to the respective cells after the cells are substantially discharged via a drain. The register is read by a control element to define therefrom a row of pixel information.

Claims

1. Apparatus, comprising:

a plurality of detectors arranged as a plurality of lines, for receiving image information and providing a proportionate level of charge therefrom;

a plurality of cells forming a charge coupled device (CCD) register, each of said detectors having associated with it a respective cell;

a drain gate, for controllably removing charge from said plurality of cells; and

a controller, for causing said drain gate to sequentially remove residual charge from said cells along one of said plurality of lines at a time, causing said cells to receive charge levels proportionate to said respective detectors, and retrieve charge-level indicative information from said cells.

2. The apparatus of claim 1, wherein each of said detectors is formed in a common substrate, said substrate including thereon non-detector portions operating as drains to reduce dark current charge proximate said detectors.

3. The apparatus of claim 1, wherein each of said detectors is formed in a common substrate, said substrate including thereon non-detector portions operating as drains to provide blooming control.

4. The apparatus of claim 1, further comprising a plurality of focusing elements, each of said focusing elements having associated with it a respective detector, said focusing elements operating to increase the amount of image information applied to each detector.

5. The apparatus of claim 4, wherein:

said detectors and said respective focusing elements are arranged as said plurality of lines forming thereby a detector array, wherein each of said plurality of detector lines has associated with it a respective register; and

said controller processing each of said detector lines in sequence by discharging said respective register, causing each cell within said respective register to receive charge from a corresponding detector, and retrieving charge-indicative information from said register.

6. The apparatus of claim 1, wherein a drain and dump gate is formed proximate said plurality of detectors to controllably provide dark current reduction and blooming control.

7. The apparatus of claim 6, wherein said drain and dump gates are used to provide shutter control.

8. The apparatus of claim 1, wherein said detectors comprise one of a pinned virtual gage detector or a diode detector.

9. The apparatus of claim 1, wherein said detectors are responsive to one of visible light and infrared radiation.

10. The apparatus of claim 1, further comprising:

an amplifier, coupled between said CCD register and said controller, for adapting a signal level to charge levels of said CCD register cells.

11. The apparatus of claim 10, wherein said amplifier comprises a floating diffusion amplifier.

12. Apparatus, comprising:

a plurality of detectors arranged as a plurality of lines for receiving image information and providing a proportionate level of charge therefrom;

a plurality of cells forming a charge coupled device (CCD) register, each of said detectors having associated with it a respective cell; and

a controller, for sequentially removing residual charge from said cells along one of said plurality of lines at a time, causing said cells to receive charge levels proportionate to said respective detectors, and retrieving charge-level indicative information from said cells.

13. The apparatus of claim 12, wherein said controller removes residual charge from said cells by reading said register prior to causing said cells within said register to receive respective charge levels from said detectors.

14. The apparatus of claim 12, wherein a plurality of CCD registers are arranged to form a corresponding plurality of lines in a frame, said controller operating to read two CCD registers simultaneously, a first of said CCD registers being read to clear residual charge from cells forming said first register, a second of said CCD registers being read to receive charge levels proportionate to detectors associated with cells therein, said second CCD register having been cleared using a previous read operation.

15. The apparatus of claim 12, wherein each of said detectors is formed in a common substrate, said substrate including thereon non-detector portions operating as drains to reduce dark current charge proximate said detectors.

16. The apparatus of claim 12, wherein said detectors and said cells are formed on a common substrate.

17. The apparatus of claim 12, wherein said apparatus is formed using a semiconductor material comprising at least one of silicon and geranium.

18. The apparatus of claim 12, further comprising:

a scan converter, for adapting the scan rate of the retrieved charge-level indicative information from the cells and adapting said scan rate to the predetermined scan rate.

19. An integrated circuit formed using a complementary metal-oxide semiconductor/charge coupled device (CMOS/CCD) process on a common substrate, said integrated circuit comprising:

a plurality of detectors arranged as a plurality of lines for receiving image information and providing a proportionate level of charge therefrom;

a plurality of cells forming a charge coupled device (CCD) register, each of said detectors having associated with it a respective cell;

a drain gate, for controllably removing charge from said plurality of cells; and

a controller, for causing said drain gate to sequentially remove residual charge from said cells along one of said plurality of lines at a time, causing said cells to receive charge levels proportionate to said respective detectors, and retrieve charge-level indicative information from said cells.

20. The integrated circuit of claim 19, wherein each of said detectors is formed in a common substrate, said substrate including thereon non-detector portions operating as drains to reduce dark current change proximate said detectors.

21. The integrated circuit of claim 19, wherein each of said detectors is formed in a common substrate, said substrate including thereon non-detector portions operating as drains to provide blooming control.

22. The integrated circuit of claim 19, further comprising a plurality of focusing elements, each of said focusing elements having associated with it a respective detector, said focusing elements operating to increase the amount of image information applied to each detector.

23. The integrated circuit of claim 22, wherein:

said detectors and said respective focusing elements are arranged as said plurality of lines forming thereby a detector array wherein each of said plurality of detector lines has associated with it a respective register;

said controller processing each of said detector lines in sequence by discharging said respective register, causing each cell within said respective register to receive charge from a corresponding detector, and retrieving charge-indicative information from said register.

24. A method, comprising the steps of:

clearing dark current from a charge coupled device (CCD) register;

loading detector signals into corresponding cells within the CCD register;

retrieving the contents of the CCD register; and

repeating the preceding steps for each line of a CCD array.

25. The method of claim 24, wherein said step of clearing comprises the step of reading said CCD register prior to said step of loading.

26. The method of claim 25, wherein said step of clearing and said step of loading are simultaneously performed on respective CCD registers.

27. The method of claim 24, wherein said detector signals are provided by respective detectors formed in a common substrate, said substrate including thereon non-detector portions operating as drains to provide blooming control.

28. A method, comprising:

sequentially accessing each pair of adjacent lines of charge coupled device (CCD) cells within an array of CCD cells, each cell receiving image indicative charge from a respective detector;

for each pair of adjacent lines of CCD cells, said accessing operating to retrieve image indicative charge from a first adjacent line of CCD cells and to clear dark current from a second line of CCD cells, said first adjacent line of CCD cells having been substantially cleared of dark current by an immediately preceding access.