Image sensing apparatus driving method, image sensing apparatus, and image sensing system

• US 7,982,789 B2
• Filed: 07/07/2008
• Issued: 07/19/2011
• Est. Priority Date: 07/11/2007
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Itano, Tetsuya, Watanabe, Takanori, Takahashi, Hidekazu
• Primary Examiner(s): Chan; Jason
• Assistant Examiner(s): SEGURA, CYNTHIA
• Application Number:
  US12/168,506
• Publication Number:
  US 20090015699A1
• Time in Patent Office: 1,107 Days
• Field of Search: 348/308, 348/302
• US Class Current: 348/308
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 25/136 using complementary colours

Abstract

Since pixel signals are not only added in the row direction but also averaged in the column direction, it is possible to sufficiently increase the frame rate even when the number of pixels increases. Additionally, since the spatial centers of gravity of the added or averaged signals are arranged at equal intervals in a Bayer array, it is possible to reduce false color (moiré) generation and suppress the decrease in the spatial resolution.

Claims

1. A method of driving an image sensing apparatus including an image sensing region, which includes a plurality of photoelectric conversion units arranged in a column direction and in a row direction, a plurality of column signal lines each capable of transferring, for each column, a signal corresponding to electric carriers of each of the plurality of photoelectric conversion units, and a plurality of color filters each of which selectively transmits one of light components of a first color, a second color, a third color, and a fourth color, the method comprising:

a first step of adding signals of at least two photoelectric conversion units arranged in the column direction in the image sensing region; and

a second step of adding or averaging, for at least two columns, signals output via the plurality of column signal lines after the first step,

wherein, in the image sensing region, a plurality of unit arrays are arranged in the column direction and in the row direction, each of the plurality of unit arrays including

four first photoelectric conversion units, on which the light component of the first color is incident, signals of which are to be added in the first step and to be added or averaged in the second step,

two second photoelectric conversion units, on which the light component of the second color is incident, signals of which are not to be added in the first step but to be added or averaged in the second step,

two third photoelectric conversion units, on which the light component of the third color is incident, signals of which are to be added in the first step but not to be added or averaged in the second step, and

a fourth photoelectric conversion unit, on which the light component of the fourth color is incident, signals of which are neither to be added in the first step nor to be added or averaged in the second step,

wherein one of the four first photoelectric conversion units and the fourth photoelectric conversion unit are arranged on a first diagonal line in the unit array,

wherein one of the two second photoelectric conversion units and one of the two third photoelectric conversion units are arranged on a second diagonal line in the unit array, and

wherein an array formed by a center of gravity of the four first photoelectric conversion units, a center of gravity of the two second photoelectric conversion units, a center of gravity of the two third photoelectric conversion units, and a center of gravity of the fourth photoelectric conversion unit is a Bayer array.

2. The method according to claim 1, wherein

the plurality of color filters include

a first color filter, which selectively transmits the light component of the first color to make the light component of the first color incident on the first photoelectric conversion unit,

a second color filter, which selectively transmits the light component of the second color to make the light component of the second color incident on the second photoelectric conversion unit,

a third color filter, which selectively transmits the light component of the third color to make the light component of the third color incident on the third photoelectric conversion unit, and

a fourth color filter, which selectively transmits the light component of the fourth color to make the light component of the fourth color incident on the fourth photoelectric conversion unit,

wherein an array of the plurality of color filters is a Bayer array.

3. The method according to claim 1,

wherein, in the image sensing region, a plurality of pixel units are arranged in the column direction and in the row direction, each of the plurality of pixel units including

at least four photoelectric conversion units arranged in the column direction,

a carrier holding unit which holds electric carriers accumulated in at least one of the at least four photoelectric conversion units, and

at least four carrier transfer units which transfer the electric carriers generated in at least one of the at least four photoelectric conversion units to the carrier holding unit, and

wherein, in the first step, the at least four carrier transfer units add the signals generated in two or more photoelectric conversion units by transferring electric carriers from the two or more of the at least four photoelectric conversion units to the carrier holding unit.

4. The method according to claim 1,

wherein the image sensing apparatus further includes

a readout unit, which reads out signals from the plurality of photoelectric conversion units via the plurality of column signal lines, and

a horizontal signal line, which receives the signals from the readout unit, and

wherein, in the second step, the readout unit adds, for at least two columns, signals output via the plurality of column signal lines by averaging the signals of the at least two columns and outputting all of the averaged signals to the horizontal signal line, or averages by averaging the signals of the at least two columns and outputting one of the averaged signals to the horizontal signal line.

5. The method according to claim 4,

wherein the readout unit includes

a first readout circuit connected to one end of each of at least some of the plurality of column signal lines, and

a second readout circuit connected to the other end of each of at least some of the plurality of column signal lines,

wherein the horizontal signal line includes

a first horizontal signal line, which receives a signal from the first readout circuit, and

a second horizontal signal line, which receives a signal from the second readout circuit, and

wherein, in the second step, an operation of causing the first readout circuit to supply a signal to the first horizontal signal line and an operation of causing the second readout circuit to supply a signal to the second horizontal signal line are performed in parallel.

6. A method of driving an image sensing apparatus including an image sensing region, which includes a plurality of photoelectric conversion units arranged in a column direction and in a row direction, a plurality of column signal lines each capable of transferring, for each column, a signal corresponding to electric carriers of each of the plurality of photoelectric conversion units, and a plurality of color filters each of which selectively transmits one of light components of a fifth color, a sixth color, a seventh color, and an eighth color, the method comprising:

a first step of adding signals of at least two photoelectric conversion units arranged in the column direction in the image sensing region; and

a second step of adding or averaging, for at least two columns, signals output via the plurality of column signal lines after the first step,

wherein, in the image sensing region, a plurality of unit arrays are arranged in the column direction and in the row direction, each of the plurality of unit arrays including

two fifth photoelectric conversion units, on which the light component of the fifth color is incident, signals of which are not to be added in the first step but to be added or averaged in the second step,

two sixth photoelectric conversion units, on which the light component of the sixth color is incident, signals of which are to be added in the first step but not to be added or averaged in the second step,

a seventh photoelectric conversion unit, on which the light component of the seventh color is incident, a signal of which is neither to be added in the first step nor to be added or averaged in the second step, and

an eighth photoelectric conversion unit, on which the light component of the eighth color is incident, a signal of which is neither to be added in the first step nor to be added or averaged in the second step,

wherein one of the two fifth photoelectric conversion units and one of the two sixth photoelectric conversion units are arranged on a first diagonal line in the unit array,

wherein the seventh photoelectric conversion unit and the eighth photoelectric conversion unit are arranged on a second diagonal line in the unit array, and

wherein an array formed by a center of gravity of the two fifth photoelectric conversion units, a center of gravity of the two sixth photoelectric conversion units, a center of gravity of the seventh photoelectric conversion unit, and a center of gravity of the eighth photoelectric conversion unit is a Bayer array.

7. The method according to claim 6,

wherein the plurality of color filters include

a fifth color filter, which selectively transmits the light component of the fifth color to make the light component of the fifth color incident on the fifth photoelectric conversion unit,

a sixth color filter, which selectively transmits the light component of the sixth color to make the light component of the sixth color incident on the sixth photoelectric conversion unit,

a seventh color filter, which selectively transmits the light component of the seventh color to make the light component of the seventh color incident on the seventh photoelectric conversion unit, and

an eighth color filter, which selectively transmits the light component of the eighth color to make the light component of the eighth color incident on the eighth photoelectric conversion unit, and

wherein an array of the plurality of color filters is a Bayer array.

8. The method according to claim 6,

wherein, in the image sensing region, a plurality of pixel units are arranged in the column direction and in the row direction, each of the plurality of pixel units including

at least four photoelectric conversion units arranged in the column direction,

a carrier holding unit, which holds electric carriers accumulated in at least one of the at least four photoelectric conversion units, and

at least four carrier transfer units, which transfer the electric carriers generated in at least one of the at least four photoelectric conversion units to the carrier holding unit, and

wherein, in the first step, the at least four carrier transfer units add the signals generated in two or more photoelectric conversion units by transferring electric carriers from the two or more of the at least four photoelectric conversion units to the carrier holding unit.

9. The method according to claim 6,

wherein the image sensing apparatus further includes

a readout unit, which reads out signals from the plurality of photoelectric conversion units via the plurality of column signal lines, and

a horizontal signal line, which receives the signals from the readout unit, and

wherein, in the second step, the readout unit adds, for at least two columns, signals output via the plurality of column signal lines by averaging the signals of the at least two columns and outputting all of the averaged signals to the horizontal signal line, or averages by averaging the signals of the at least two columns and outputting one of the averaged signals to the horizontal signal line.

10. The method according to claim 9,

wherein the readout unit includes

a first readout circuit connected to one end of each of at least some of the plurality of column signal lines, and

a second readout circuit connected to the other end of each of at least some of the plurality of column signal lines,

wherein the horizontal signal line includes

a first horizontal signal line which receives a signal from the first readout circuit, and

a second horizontal signal line which receives a signal from the second readout circuit, and

wherein, in the second step, an operation of causing the first readout circuit to supply the signal to the first horizontal signal line and an operation of causing the second readout circuit to supply the signal to the second horizontal signal line are performed in parallel.

11. An image sensing apparatus comprising:

a plurality of color filters each of which selectively transmits one of light components of a first color, a second color, a third color, and a fourth color;

an image sensing region which includes a plurality of photoelectric conversion units arranged in a column direction and in a row direction, and a plurality of adding units each capable of adding, for each column, signals of at least four of the plurality of photoelectric conversion units arranged in the column direction;

a plurality of column signal lines each capable of transferring a signal corresponding to electric carriers of each of the plurality of photoelectric conversion units; and

an adding/averaging unit capable of adding or averaging, for at least two columns, the signals transferred via the plurality of column signal lines,

wherein, in the image sensing region, a plurality of unit arrays are arranged in the column direction and in the row direction, each of the plurality of unit arrays including

four first photoelectric conversion units on which the light component of the first color is incident, signals of which are to be added by the adding unit and to be added or averaged by the adding/averaging unit,

two second photoelectric conversion units on which the light component of the second color is incident, signals of which are not to be added by the adding unit but to be added or averaged by the adding/averaging unit,

two third photoelectric conversion units on which the light component of the third color is incident, signals of which are to be added by the adding unit but not to be added or averaged by the adding/averaging unit, and

a fourth photoelectric conversion unit on which the light component of the fourth color is incident, signals of which are neither to be added by the adding unit nor to be added or averaged by the adding/averaging unit,

wherein one of the four first photoelectric conversion units and the fourth photoelectric conversion unit are arranged on a first diagonal line in the unit array,

wherein one of the two second photoelectric conversion units and one of the two third photoelectric conversion units are arranged on a second diagonal line in the unit array, and

wherein an array formed by a center of gravity of the four first photoelectric conversion units, a center of gravity of the two second photoelectric conversion units, a center of gravity of the two third photoelectric conversion units, and a center of gravity of the fourth photoelectric conversion unit is a Bayer array.

12. An image capturing system comprising:

an image sensing apparatus of claim 11;

an optical system, which forms an image of light on the image sensing region of the image sensing apparatus; and

a signal processing unit, which processes a signal output from the image sensing apparatus to generate image data.

13. An image sensing apparatus comprising:

a plurality of color filters each of which selectively transmits one of light components of a fifth color, a sixth color, a seventh color, and an eighth color;

an image sensing region, which includes a plurality of photoelectric conversion units arranged in a column direction and in a row direction, and a plurality of adding units each capable of adding, for each column, signals of at least four of the plurality of photoelectric conversion units arranged in the column direction;

a plurality of column signal lines each capable of transferring a signal corresponding to electric carriers of each of the plurality of photoelectric conversion units; and

an adding/averaging unit capable of adding or averaging, for at least two columns, the signals transferred via the plurality of column signal lines,

wherein in the image sensing region, a plurality of unit arrays are arranged in the column direction and in the row direction, each of the plurality of unit arrays including

two fifth photoelectric conversion units on which the light component of the fifth color is incident, signals of which are not to be added by the adding unit but to be added or averaged by the adding/averaging unit,

two sixth photoelectric conversion units on which the light component of the sixth color is incident, signals of which are to be added by the adding unit but not to be added or averaged by the adding/averaging unit,

a seventh photoelectric conversion unit on which the light component of the seventh color is incident, signals of which is neither to be added by the adding unit nor to be added or averaged by the adding/averaging unit, and

an eighth photoelectric conversion unit on which the light component of the eighth color is incident, signals of which is neither to be added by the adding unit nor to be added or averaged by the adding/averaging unit,

wherein one of the two fifth photoelectric conversion units and one of the two sixth photoelectric conversion units are arranged on a first diagonal line in the unit array, and

wherein the seventh photoelectric conversion unit and the eighth photoelectric conversion unit are arranged on a second diagonal line in the unit array.

14. An image capturing system comprising:

an image sensing apparatus of claim 13;

an optical system, which forms an image of light on the image sensing region of the image sensing apparatus; and

a signal processing unit, which processes a signal output from the image sensing apparatus to generate image data.