CHARGE-COUPLED DEVICE IMAGE SENSOR WITH EFFICIENT BINNING OF SAME-COLOR PIXELS

• US 20100157126A1
• Filed: 12/19/2008
• Published: 06/24/2010
• Est. Priority Date: 12/19/2008
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: TRUESENSE Imaging, Inc. (ON Semiconductor Corporation)
• Inventors: Nichols, David N., Compton, John T.
• Granted Patent: US 8,164,669 B2
• Time in Patent Office: Days
• US Class Current: 348/311
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/447 by preserving the colour pattern with or without loss of information
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/70 SSIS architectures; Circuits associated therewith
• CPC Class Codes: H04N 25/71 Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
• CPC Class Codes: H04N 25/73 using interline transfer [IT]

Abstract

A CCD image sensor comprises photosensitive elements arranged in rows and columns, vertical CCDs each having vertical shift elements associated with respective ones of the photosensitive elements of a corresponding one of the columns, and a horizontal CCD coupled to each of the vertical CCDs. The horizontal CCD comprises horizontal shift elements of two different types interspersed with one another. The horizontal shift elements of the first type are configured to receive shifted charge packets directly from respective ones of the vertical CCDs. The horizontal shift elements of the second type are configured not to receive shifted charge packets directly from any of the vertical CCDs. This configuration facilitates binning of same-color pixels for both sparse CFA patterns and Bayer CFA patterns.

Claims

1. A charge-coupled device (CCD) image sensor, comprising:

a plurality of photosensitive elements arranged in rows and columns;

a plurality of vertical CCDs each having vertical shift elements associated with respective ones of the photosensitive elements of a corresponding one of the columns; and

a horizontal CCD coupled to each of the vertical CCDs;

wherein the horizontal CCD comprises horizontal shift elements of two different types interspersed with one another, with horizontal shift elements of the first type being configured to receive shifted charge packets directly from respective ones of the vertical CCDs and horizontal shift elements of the second type being configured not to receive shifted charge packets directly from any of the vertical CCDs.

2. The image sensor of claim 1 wherein the number of horizontal shift elements in the horizontal CCD is at least 50% greater than the number of vertical CCDs.

3. The image sensor of claim 1 wherein the horizontal shift elements comprise two-phase horizontal shift elements.

4. The image sensor of claim 1 wherein the horizontal CCD is operative in at least first and second different modes of operation, wherein in the first mode of operation the number of horizontal shift elements in the horizontal CCD is greater than the number of vertical CCDs and in the second mode of operation the number of horizontal shift elements in the horizontal CCD is equal to the number of vertical CCDs.

5. The image sensor of claim 1 wherein the photosensitive elements are configured in accordance with a sparse color filter array pattern.

6. The image sensor of claim 5 wherein the horizontal CCD is configured to provide binning of same-color charge packets without binning of panchromatic charge packets.

7. The image sensor of claim 6 wherein the binning of same-color charge packets without binning of panchromatic charge packets is provided for a pair of the rows of photosensitive elements by a readout process that comprises a vertical shift in the vertical CCDs, followed by a horizontal shift in the horizontal CCD, followed by another vertical shift in the vertical CCDs.

8. The image sensor of claim 5 wherein a minimal repeating unit of the sparse color filter array pattern comprises 16 contiguous pixels arranged as follows:

Y P X P P Y P X Z P Y P P Z P Y

where P represents a panchromatic pixel and X, Y and Z represent pixels having first, second and third colors, respectively.

9. The image sensor of claim 1 wherein the photosensitive elements are configured in accordance with a Bayer color filter array pattern.

10. The image sensor of claim 9 wherein the horizontal CCD comprises a bidirectional horizontal CCD.

11. The image sensor of claim 10 wherein the horizontal CCD is configured to provide binning of four green charge packets, binning of two red charge packets and binning of two blue charge packets.

12. The image sensor of claim 11 wherein the binning of four green charge packets, binning of two red charge packets and binning of two blue charge packets is provided for a given set of two pairs of adjacent ones of the rows by a readout process that comprises a first vertical shift in the vertical CCDs, followed by a shift in a first direction in the horizontal CCD, followed by a second vertical shift in the vertical CCDs, followed by a shift in a second direction in the horizontal CCD, followed by a third vertical shift in the vertical CCDs, followed by another shift in the first direction in the horizontal CCD, followed by a fourth vertical shift in the vertical CCDs.

13. The image sensor of claim 10 wherein the horizontal CCD is configured to provide binning of three green charge packets, binning of either two red charge packets or two blue charge packets, and no binning of charge packets of the remaining color.

14. A method of reading out a charge-coupled device (CCD) image sensor, the image sensor comprising a plurality of photosensitive elements arranged in rows and columns, the method comprising the steps of:

shifting charge packets through a plurality of vertical CCDs each having vertical shift elements associated with respective ones of the photosensitive elements of a corresponding one of the columns; and

shifting the charge packets through a horizontal CCD coupled to each of the vertical CCDs;

wherein the horizontal CCD comprises horizontal shift elements of two different types interspersed with one another, with horizontal shift elements of the first type being configured to receive shifted charge packets directly from respective ones of the vertical CCDs and horizontal shift elements of the second type being configured not to receive shifted charge packets directly from any of the vertical CCDs.

15. The method of claim 14 wherein the horizontal CCD is operative in at least first and second different modes of operation, wherein in the first mode of operation the number of horizontal shift elements in the horizontal CCD is greater than the number of vertical CCDs and in the second mode of operation the number of horizontal shift elements in the horizontal CCD is equal to the number of vertical CCDs.

16. The method of claim 14 wherein the shifting steps further comprise a vertical shift in the vertical CCDs, followed by a horizontal shift in the horizontal CCD, followed by another vertical shift in the vertical CCDs.

17. The method of claim 14 wherein the shifting steps further comprise at least a first vertical shift in the vertical CCDs, followed by a shift in a first direction in the horizontal CCD, followed by a second vertical shift in the vertical CCDs, followed by a shift in a second direction in the horizontal CCD, followed by a third vertical shift in the vertical CCDs, followed by another shift in the first direction in the horizontal CCD, followed by a fourth vertical shift in the vertical CCDs.

18. The method of claim 14 wherein the photosensitive elements are configured in accordance with a sparse color filter array pattern and the shifting steps provide binning of same-color charge packets without binning of panchromatic charge packets.

19. A digital imaging device comprising:

a charge-coupled device (CCD) image sensor; and

one or more processing elements configured to process outputs of the image sensor to generate a digital image;

wherein said image sensor comprises;

a plurality of photosensitive elements arranged in rows and columns;

a plurality of vertical CCDs each having vertical shift elements associated with respective ones of the photosensitive elements of a corresponding one of the columns; and

a horizontal CCD coupled to each of the vertical CCDs;

wherein the horizontal CCD comprises horizontal shift elements of two different types interspersed with one another, with horizontal shift elements of the first type being configured to receive shifted charge packets directly from respective ones of the vertical CCDs and horizontal shift elements of the second type being configured not to receive shifted charge packets directly from any of the vertical CCDs.

20. The digital imaging device of claim 19 wherein said digital imaging device comprises a digital camera.