Multi-photodetector unit cell

• US 6,693,670 B1
• Filed: 07/31/2000
• Issued: 02/17/2004
• Est. Priority Date: 07/29/1999
• Status: Expired due to Fees

• Current Assignee: Vision-Sciences Incorporated (2941881 Canada, Inc.)
• Original Assignee: Vision-Sciences Incorporated (2941881 Canada, Inc.)
• Inventors: Stark, Moshe
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US09/629,703
• Time in Patent Office: 1,296 Days
• Field of Search: H04/N.5335, 348/294, 348/295, 348/297, 348/302, 348/308, 348/362, 348/216.1, 348/217.1, 348/296, 348/241, 348/222.1, 250/208.1
• US Class Current: 348/308
• CPC Class Codes: H04N 25/42 by switching between different modes of operation using different resolutions or aspect ratios, e.g. switching between interlaced and non-interlaced mode
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/778 comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself

Abstract

A multi-cell cluster which includes a plurality of light-detecting unit cells and a single charge-integration and readout circuitry. Typically, each of the cells produces charge representative of the detected light. The circuit may be shared by the plurality of unit cells, and used to read-out the charge in real-time. The cluster may also Include a switch associated with each unit cell, such that each switch connects its associated unit cell to the circuit. The switch may also be controlled in a time-multiplexing manner. Each unit cell may include a photodetector, a photodiode, or a photogate. The circuit may include a shared storage device, a shared reset circuit, or a readout circuit. Typically, the shared storage device may be for accumulating the charge in the focal plane. The here-above described apparatus facilitates either static or dynamic, either local or global image resolution/sensitivity tradeoffs.

Claims

1. A plurality of multi-cell clusters adaptable for use in an imaging sensor, each cluster of said multi-cell clusters comprising:

a plurality of light detecting unit cells, each of said unit cells is configured to produce charge representative of light incident thereupon; and

a circuit comprising a single storage device shared by said plurality of unit cells, said circuit is configured to accumulate in generally real-time the charge from any selected combination of unit cells of the cluster and to read-out said charge for controlling the resolution and the signal to noise ratio of said imaging sensor.

2. The plurality of multi-cell clusters according to claim 1, wherein each cluster of said plurality of multi-cell clusters comprises a plurality of switches, each switch of said plurality of switches is associated with a unit cell of said plurality of unit cells, each switch of said plurality of switches is configured to connect its associated unit cell to said circuit, each switch is configured to be controlled in a time-multiplexing manner.

3. The plurality of multi-cell clusters according to claim 1, wherein each unit cell of said plurality of unit cells comprises a light sensing device selected from the group consisting of a photodetector, a photodiode, and a photogate.

4. The plurality of multi-cell clusters according to claim 1, wherein said circuit also comprises a shared reset circuit.

5. The plurality of multi-cell clusters according to claim 1, wherein said circuit also comprises a shared readout circuit.

21. The plurality of multi-cell clusters according to claim 1, wherein said storage device is implemented in the focal plane of said imaging sensor for accumulating said charge.

6. A sensing array comprising:

a multiplicity of clusters, each cluster of said clusters comprising;

a two-dimensional plurality of unit cells for detecting light and producing charge representative of said light; and

a circuit comprising a single storage device shared exclusively by said plurality of unit cells of said cluster, said circuit is configured to control an integration cycle of said unit cells, and to accumulate in generally real-time the charge from any selected combination of unit cells of said cluster and to read-out said charge for controlling the resolution and the signal to noise ratio of said sensing array;

a plurality of read-row lines, each read-row line is operatively connected to a row of clusters, for reading the accumulated charge of each cluster in said row of clusters; and

a plurality of column sensing lines, each column sensing line is operatively connected to a column of said clusters, for sensing the sampled charge present in each of the clusters of said column.

7. The array according to claim 6, wherein said plurality of read-row lines and said plurality of column sensing lines are configured to carry programming signals for controlling said plurality of unit cells.

8. A method for operating an image sensor having a plurality of clusters, each cluster of said plurality of clusters comprises a two-dimensional plurality of unit cells for detecting light and producing charge representative of said light and a circuit comprising a single storage device operatively coupled to said plurality of unit cells of said cluster, said circuit is configured to control an integration cycle of said unit cells and to accumulate in generally real-time the charge from any selected combination of unit cells of said cluster and to read-out said charge for controlling the resolution and the signal to noise ratio of said sensing array, the method comprising the steps of:

exposing said image sensor to light at least for the duration of said integrating cycle;

coatrollably summing, during said integrating cycle, the charge from at least one selected combination of the unit cells included in the cluster to store in said circuit at least one summed charge; and

reading out said at least one summed charge within the duration of said integrating cycle.

9. The method according to claim 8, wherein one or more unit cells of said plurality of unit cells are preprogrammed unit cells.

10. The method according to claim 8, wherein the step of reading out comprises reading out said at least one summed charge in real time.

11. The method according to claim 8, wherein said step of controllably summing comprises sequentially summing within two or more sub-cycles of said integrating cycle, the charge from two or more selected combinations of the unit cells included in the cluster to sequentially store in said circuit two or more summed charges, each charge of said two or more summed charges represents the total charge simultaneously summed from all unit cells included within a single combination of said two or more selected combinations.

12. The method according to claim 8, wherein said step of controllably summing comprises the step of summing the charge from each unit cell within a cluster separately and sequentially within Sub-cycles of said integrating cycle.

13. The method according to claim 8, wherein said step of controllably summing comprises the step of substantially simultaneously summing charge from two or more of said unit cells of the same cluster within said integrating cycle.

14. The method according to claim 8, wherein said step of controllably summing comprises the step of substantially simultaneously summing the charge from all of the unit cells in a cluster within said integrating cycle.

15. The method according to claim 8, wherein said steps of controllably summing and reading out are performed for all clusters of said plurality of clusters, and further comprising the step of combining all of the summed charges read out from all of said clusters within said integrating cycle into a single image.

16. The method according to claim 8, further comprising the step of dynamically controlling the resolution and the signal to noise ratio of said sensing array by dynamically controlling one or more of,

the number of unit cells in said at least one selected combination of unit cells,

the spatial arrangement of unit cells in said at least one selected combination of unit cells, and

the number and the spatial arrangement of unit cells in said at least one selected combination of unit cells.

17. The method according to claim 16, wherein said step of dynamically controlling comprises the step of determining the number or the spatial arrangement, or the number and the spatial arrangement of unit cells in said at least one selected combination of said step of controllably summing, depending on light conditions.

18. The method according to claim 16, wherein said steps of exposing, controllably summing, and dynamically controlling are performed in generally real-time.

19. The method according to claim 8, further comprising the step of improving the signal to noise ratio of said image sensor by increasing the number of the unit cells in said at least one selected combination.

20. The method according to claim 8, further comprising the step of:

improving the resolution of said image sensor by decreasing the number of unit cells in each selected combination of said at least one selected combination; and

reading within said integrating cycle the summed charges of said at least one summed charge of a cluster separately in a time-multiplexing manner.

22. A plurality of multi-cell clusters adaptable for use in an imaging sensor, each cluster of said multi-cell clusters comprising:

a two-dimensional plurality of light detecting unit cells, each of said unit cells is configured to produce charge representative of light incident thereupon; and

a circuit configured to accumulate and to read-out charge in generally real-time from one or more of said unit cells, said circuit comprises a single storage device controllably and simultaneously connectable to any desired combination of said unit cells, said circuit is configured to allow simultaneously accumulating the charge from any desired combination of unit cells within the cluster.

23. A sensing array comprising:

a multiplicity of clusters, each cluster of said clusters comprising;

a two-dimensional plurality of unit cells for detecting light and producing charge representative of said light; and

a circuit shared exclusively by said plurality of unit cells of said cluster, said circuit is configured to control an integration cycle of said unit cells, and to accumulate said charge, said circuit comprises a single storage device controllably connectable to any desired combination of said unit cells, said circuit is configured to allow simultaneously accumulating the charge from any desired combination of unit cells within the cluster;

a plurality of read-row lines, each read-row line is operatively connected to a row of clusters, for reading the accumulated charge of each cluster in said row of clusters; and

a plurality of column sensing lines, each column sensing line is operatively connected to a column of said clusters for sensing the sampled charge present in each of the clusters of said column.

24. A method for operating an image sensor having a plurality of clusters, each cluster of said plurality of clusters comprises a two-dimensional plurality of unit cells for detecting light and producing charge representative of said light and a circuit comprising a single storage device operatively coupled to said plurality of unit cells of said cluster, said circuit is configured to control an integration cycle of said unit cells and to controllably accumulate charge from one or more of the unit cells of said cluster, the method comprising the steps of:

exposing at least part of said image sensor to light;

controllably selecting a desired combination of unit cells from the plurality of unit cells included in a cluster, wherein said desired combination is selectable from all the combinations of unit cells possible for said cluster;

simultaneously summing in said circuit the charge from the unit cells included in said desired combination of unit cells selected in said step of controllably selecting to store in said circuit a summed charge; and

reading out said summed charge.