High dynamic range imager with a rolling shutter
First Claim
1. A pixel reading circuit, comprising:
- a signal input node for receiving a reset signal, a first photo signal, and a second photo signal;
a first sample and hold circuit coupled to a signal input node;
a second sample and hold circuit coupled to said signal input node;
a third sample and hold circuit coupled to said signal input node;
a first output circuit, coupled to receive signals from said first and second sample and hold circuits; and
a second output circuit, coupled to receive signals from said first and third sample and hold circuits.
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Abstract
A high dynamic range imager operates pixels utilizing at least a short integration period and a long integration period. The pixel reading circuits of the imager are adapted to process pixel signals corresponding to the integration periods in parallel. The pixel signals are converted into digital values in parallel. The digital values are each linear functions of the incident light and therefore suitable for use with conventional color processing algorithms. A pipelined rolling shutter operation may be employed where the short integration period of one row of pixels is performed simultaneously with the long integration period of another row of pixels.
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Citations
34 Claims
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1. A pixel reading circuit, comprising:
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a signal input node for receiving a reset signal, a first photo signal, and a second photo signal;
a first sample and hold circuit coupled to a signal input node;
a second sample and hold circuit coupled to said signal input node;
a third sample and hold circuit coupled to said signal input node;
a first output circuit, coupled to receive signals from said first and second sample and hold circuits; and
a second output circuit, coupled to receive signals from said first and third sample and hold circuits. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An imager, comprising:
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a pixel array comprising a plurality of pixels arranged in a plurality of rows and a plurality of columns;
a plurality of pixel reading circuits, each of said pixel reading circuits comprising;
a first, second, and third sample and hold circuits, for respectively sampling and holding a reset signal, a first photo signal, and a second photo signal, from one of said plurality of pixels;
a first output circuit for producing a first pixel signal from said reset signal and said first photo signal; and
a second output circuit for producing a second pixel signal from said reset signal and said second photo signal;
a first analog to digital converter, coupled to said first output circuit, for producing a first digital value corresponding to said first pixel signal; and
a second analog to digital converter, coupled to said second output circuit, for producing a second digital value corresponding to said second pixel signal. - View Dependent Claims (8, 9, 10, 11)
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12. A system, comprising:
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a processor;
an imager coupled to said processor, said imager comprising;
a pixel array comprising a plurality of pixels arranged in a plurality of rows and a plurality of columns;
a plurality of pixel reading circuits, each of said pixel reading circuits comprising;
a first, second, and third sample and hold circuits, for respectively sampling and holding a reset signal, a first photo signal, and a second photo signal, from one of said plurality of pixels;
a first output circuit for producing a first pixel signal from said reset signal and said first photo signal; and
a second output circuit for producing a second pixel signal from said reset signal and said second photo signal;
a first analog to digital converter, coupled to said first output circuit, for producing a first digital value corresponding to said first pixel signal; and
a second analog to digital converter, coupled to said second output circuit, for producing a second digital value corresponding to said second pixel signal. - View Dependent Claims (13, 14, 15, 16)
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17. A method for reading a pixel, comprising:
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(a) sampling and holding a first photo signal from said pixel;
(b) sampling and holding a reset signal from said pixel;
(c) sampling and holding a second photo signal from said pixel;
(d) forming a first output signal from said first photo signal and said reset signal; and
(e) forming a second output signal from said second photo signal and said reset signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 34)
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26. A method of operating an imager, comprising:
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(a) selecting a first row from a plurality of rows, each comprising a plurality of pixels, of a pixel array;
(b) resetting each pixel in said first row to start a first integration period;
(c) in each pixel of said first row, starting a first temporary transfer of charge accumulated during said first integration period to a charge accumulation node, and starting a second integration period at the end of said first temporary transfer;
(d) in each pixel of said first row, outputting a first photo signal associated with said first integration period;
(e) resetting each pixel in said first row to output a first reset signal;
(f) in each pixel of said first row, outputting a second photo signal associated with said second integration period. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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Specification