Solid-state imaging apparatus, driving method thereof and imaging system

• US 8,730,345 B2
• Filed: 06/02/2009
• Issued: 05/20/2014
• Est. Priority Date: 06/06/2008
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Watanabe, Takanori
• Primary Examiner(s): WILKES, ZACHARY W
• Application Number:
  US12/476,487
• Publication Number:
  US 20090303365A1
• Time in Patent Office: 1,813 Days
• Field of Search: 348/226.1, 348/228.1, 348/241, 348/296, 348300-301
• US Class Current: 348/226.1
• CPC Class Codes: H01L 27/14641 Electronic components shared by two or more pixel-elements, e.g. one amplifier shared by two pixel elements
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS
• 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 solid-state imaging apparatus includes: a plurality of photoelectric conversion elements arranged in a matrix and converting light into electric carriers; a transfer gate for transferring the electric carriers generated by the conversion to a floating node; a first transistor for amplifying a signal based on a voltage of the floating node and for outputting the amplified signal to a column signal line; and a second transistor for resetting the voltage of the floating node, wherein the solid-state imaging apparatus includes a transfer unit for combining signals from the column signal lines, based on the voltage of the floating nodes after the reset of the floating nodes by the second transistor, wherein outputting a signal based on the combined signals from the column signal lines based on the voltage of the floating nodes, for detecting a flicker of an imaging light source.

Claims

1. A driving method of a solid-state imaging apparatus including a plurality of pixels arranged in a matrix, each pixel including a photoelectric conversion element for converting light into electric carriers, a transfer gate for transferring the electric carriers to a floating node, a first transistor for amplifying a signal based on a voltage of the floating node and for outputting the amplified signal to a respective column signal line, and a second transistor for resetting the voltage of the floating node, the driving method comprising steps of:

reading out an image signal from the pixels in the matrix, during a frame period, by sequentially scrolling through, within the pixels in the matrix, a front curtain row, in which the photoelectric conversion elements and the floating nodes are reset, a flicker detection row, in which signals for detecting flickers are read out, and a rear curtain row, in which light signals in the photoelectric conversion elements are read out;

combining signals from the column signal lines based on the voltage of the floating node extending over regions of the plurality of pixels, during a period of maintaining the transfer gates at a non-conductive state, after resetting of the voltage of the floating nodes by the second transistors; and

outputting a signal based on the combined signals from the column signal lines, for detecting a flicker of an imaging light source.

2. The driving method according to claim 1, the method further comprising a step of:

outputting as a pixel signal, column by column, a difference signal representing a difference between a signal of the column signal lines based on the electric carriers of the floating nodes transferred by the transfer gates and a signal of the column signal lines based on a signal of the floating nodes after resetting of the voltage of the floating nodes by the second transistors.

3. The driving method according to claim 1, the method further comprising a step of:

generating a signal for detecting the flicker of the imaging light source based on light incident in a semiconductor region from the imaging light source, or based on electric-carrier diffusion within a semiconductor substrate.

4. The driving method according to claim 3, the method further comprising a step of:

outputting a pixel signal for each row of pixels, and the signal for detecting the flicker of the imaging light source for a part of the rows of the pixels.

5. A driving method of an imaging system including a solid-state imaging apparatus, which includes a plurality of pixels arranged in a matrix, each pixel including a photoelectric conversion element for converting light into electric carriers, a transfer gate for transferring the electric carriers to a floating node, a first transistor for amplifying a signal based on a voltage of the floating node and for outputting the amplified signal to a column signal line, and a second transistor for resetting the voltage of the floating node;

an analog front end (AFE) block;

a flicker detection block; and

a timing generator, the driving method comprising steps of;

reading out an image signal from the pixels in the matrix, during a frame period, by sequentially scrolling through, within the pixels in the matrix, a front curtain row, in which the photoelectric conversion elements and the floating nodes are reset, a flicker detection row, in which signals for detecting flickers are read out, and a rear curtain row, in which light signals in the photoelectric conversion elements are read out;

combining signals from the column signal lines based on the voltage of the floating node extending over regions of the plurality of pixels, during a period of maintaining the transfer gates at a non-conductive state, after resetting of the voltage of the floating nodes by the second transistors;

outputting a signal based on the combined signals from the column signal lines, for detecting a flicker of an imaging light source;

outputting as a pixel signal, column by column, a difference signal representing a difference between a signal of the column signal lines based on the electric carriers of the floating nodes transferred by the transfer gates, and a signal of the column signal lines based on a signal of the floating nodes after the reset by the second transistors; and

outputting the pixel signal for each row of pixels, and the signal for detecting the flicker of the imaging light source for part of the rows of the pixels;

inputting, from a same path within the solid-state imaging apparatus in a time series, via the AFE block, the pixel signal and the signal for detecting the flicker of the imaging light source outputted from the solid-state imaging apparatus, and outputting, via the AFE block, to different paths, the pixel signal and the signal for detecting the flicker of the imaging light source;

outputting, via the flicker detection block, a determination value indicating an existence or an inexistence of the flicker of the imaging light source, based on the signal for detecting the flicker of the imaging light source outputted from the AFE block; and

outputting, via the timing generator, a drive pulse of a flicker reducing drive mode or a normal drive mode according to the determination value.

6. A driving method of a solid-state imaging apparatus including a plurality of pixels arranged in a matrix, each pixel including a photoelectric conversion element for converting light into electric carriers, a transfer gate for transferring the electric carriers to a floating node, a first transistor for amplifying a signal based on a voltage of the floating node and for outputting the amplified signal to a respective column signal line, and a second transistor for resetting the voltage of the floating node, the driving method comprising steps of:

reading out an image signal from the pixels in the matrix, during a frame period, by sequentially scrolling through, within the pixels in the matrix, a front curtain row, in which the photoelectric conversion elements and the floating nodes are reset, a flicker detection row, in which signals for detecting flickers are read out, and a rear curtain row, in which light signals in the photoelectric conversion elements are read out;

combining signals from the column signal lines based on the voltage of the floating node extending over regions of the plurality of pixels, during a period of maintaining the transfer gates at a non-conductive state, after resetting of the voltage of the floating nodes by the second transistors; and

outputting the combined signals during a first reading period for reading the signals based on the electric carriers and the signals after resetting of the voltage of the floating nodes by the second transistors, and during a second reading period different from the first reading period.

7. The driving method according to claim 6, further comprising a step of:

detecting, based on signals read out during the second reading period, a flicker.

8. A driving method of a solid-state imaging apparatus including a plurality of pixels arranged in a matrix, each pixel including a photoelectric conversion element for converting light into electric carriers, a transfer gate for transferring the electric carriers to a floating node, a first transistor for amplifying a signal based on a voltage of the floating node and for outputting the amplified signal to a respective column signal line, and a second transistor for resetting the voltage of the floating node, the driving method comprising steps of:

reading out an image signal from the pixels in the matrix, during a frame period, by sequentially scrolling through, within the pixels in the matrix, a front curtain row, in which the photoelectric conversion elements and the floating nodes are reset, a flicker detection row, in which signals for detecting flickers are read out, and a rear curtain row, in which light signals in the photoelectric conversion elements are read out;

combining signals from the column signal lines based on the voltage of the floating node extending over regions of the plurality of pixels, during a period of maintaining the transfer gates at a non-conductive state, after resetting of the voltage of the floating nodes by the second transistors; and

detecting a flicker of an imaging light source based on the combined signals.