High intrascene dynamic range NTSC and PAL imager
First Claim
Patent Images
1. A pixel imager comprising:
- a first pixel circuit in a first pixel row for outputting at least first pixel image signal accumulated during a first integration period;
a second pixel circuit in a second pixel row for outputting a least second pixel image signal accumulated during a second integration period which is shorter than said first integration period; and
a sample and hold circuit for selectively acquiring at least one of said first and second pixel image signals and for outputting a pixel output signal which is based on at least one of (1) an average of said first and second pixel signals and (2) a selection of one of said first and second pixel image signals based on a value of said first pixel image signal.
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Abstract
The invention provides a new method and apparatus for NTSC and PAL image sensors which employs fusion of adjacent row pixel charge samples to generate image data for a row. A variety of fusion schemes are possible for fusing the pixel signals from the adjacent rows. The rows of pixels are scanned so that each scan takes an odd row signal sample and, in some cases, an adjacent even row signal sample when specified conditions are met. One sampled row of the two adjacent rows integrate an image with a first integration period while the other adjacent row integrates an image with a second integration period.
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Citations
42 Claims
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1. A pixel imager comprising:
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a first pixel circuit in a first pixel row for outputting at least first pixel image signal accumulated during a first integration period;
a second pixel circuit in a second pixel row for outputting a least second pixel image signal accumulated during a second integration period which is shorter than said first integration period; and
a sample and hold circuit for selectively acquiring at least one of said first and second pixel image signals and for outputting a pixel output signal which is based on at least one of (1) an average of said first and second pixel signals and (2) a selection of one of said first and second pixel image signals based on a value of said first pixel image signal.
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2. A pixel readout circuit comprising:
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a sample and hold circuit for sampling a first pixel signal from a first selected row of pixels having a first integration period, said sample and hold circuit being selectively operable to sample a second pixel signal from a second adjacent selected row of pixels, which has a second integration period shorter than said first integration period;
a switching circuit coupled to said sample and hold circuit for controlling sampling of said first and second pixel signals;
a comparator for determining if a sampled first pixel signal exceeds a threshold signal value;
said switching circuit operating said sample and hold circuit to sample said first pixel signal and providing said first pixel signal as an output signal if said comparator determines that said threshold is exceeded by said sampled first pixel signal, and operating said sample and hold circuit to sample and hold said second pixel signal and provide said second pixel signal as an output when said threshold is not exceeded. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A pixel readout circuit comprising:
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a sample and hold circuit for sampling a pixel signal from selected rows of pixels;
an amplifier for amplifying an output of said sample and hold circuit; and
a switching circuit coupled to said sample and hold circuit for controlling sampling of signals from a selected row of pixels, said switching circuit operating to sample and hold a first and second pixel signal from a pixel row having a first integration period and a third and fourth pixel signal from an adjacent pixel row having a second integration period;
wherein said sample and hold circuit averages said first and third pixel signals as well as said second and fourth pixel signals and provides an averaged first and second pixel signal to said amplifier - View Dependent Claims (10, 11, 12)
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13. A pixel readout circuit comprising:
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a sample and hold circuit for sampling a pixel signal from a selected row of pixels;
an amplifier for amplifying an output of said sample and hold circuit;
a switching circuit coupled to said sample and hold circuit for controlling sampling of signals from selected rows of pixels;
a comparator for determining if a selected pixel signal exceeds a threshold signal value;
said switching circuit operating to sample and hold a first and second pixel signal from a pixel row having a first integration period and a third and fourth pixel signal from a pixel row having a second integration period which is shorter than said first integration period;
wherein said switching circuit operates said sample and hold circuit to provide said first and third signal to said amplifier if said comparator determines that said threshold is exceeded by said first pixel signal, and operating said sample and hold circuit to combine said first and third pixel signals together resulting in a first averaged pixel signal and also combine said second and fourth pixel signals together resulting in a second averaged pixel signal, and providing said first and second averaged pixel signal to said amplifier when said threshold is not exceeded by said first pixel signal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method of reading out a pixel array comprising:
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outputting a first pixel image signal accumulated during a first integration period from a first pixel circuit in a first pixel row;
outputting a second pixel image signal accumulated during a second integration period which is shorter than said first integration period from a pixel circuit in a second pixel row;
selectively sampling and holding at least one of said first and second pixel signals; and
outputting a pixel output signal which is based on at least one of (1) an average of said first and second pixel signals and (2) a selection of one of said first and second pixel image signals based on a value of said first pixel image signal. - View Dependent Claims (21, 22)
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23. A method of performing a progressive scan readout of a pixel array comprising:
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selecting a pixel in a first row within a pixel array with a first integration time;
sampling and holding a pixel signal from said pixel in said first row within a sample and hold circuit;
resetting said pixel with a reset signal;
sampling and holding said reset signal as a second pixel signal;
comparing said first pixel signal with a threshold signal and determining said first pixel signal exceeds said threshold signal;
outputting said first pixel signal and second pixel signal to an amplifier circuit if said comparison determines said first signal exceeds said threshold signal; and
if said determination determines said first pixel signal does not exceed said threshold signal, discharging said first and second pixel signals held in said sample and hold circuit, selecting a pixel within a second adjacent pixel row in said pixel array, then sampling and holding a third and fourth pixel signal from said selected pixel, said third and fourth pixel signals are output into an amplifier after being sampled and held. - View Dependent Claims (24, 25)
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26. A method of performing a progressive read-out of pixels in a CMOS pixel array comprising:
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sampling a first pixel signal from a pixel in a pixel row having a first integration time;
charging said first pixel having a first integration time with a pixel reset signal and sampling said pixel reset signal as a second pixel signal;
sampling a third pixel signal from a pixel in a pixel row having a second integration time, wherein said second pixel row is adjacent to said pixel row having a first integration time;
charging said pixel having a second integration time with said pixel reset signal and sampling said pixel reset signal as a fourth pixel signal;
combining said first and second pixel signals to produce a first averaged pixel signal;
combining said third and fourth pixel signals to produce a second averaged pixel signal;
outputting said first and second averaged signals; and
repeating said progressive read-out if another pixel row having a first integration time and an adjacent second pixel row having a second integration time has unsampled signals from a current said first and second integration period. - View Dependent Claims (27)
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28. A method for performing progressive readout of a pixel array comprising:
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performing integration operations with a plurality of pixels within a pixel array, said pixel array comprised of pairs of an odd and adjacent even pixel row, said odd pixel rows having a first integration time and said even pixel rows having a second integration time;
sampling and holding a first pixel signal from a pixel in an odd pixel row in a sample and hold circuit;
charging said pixel with a pixel reset signal;
sampling and holding a second pixel signal from said pixel in said sample and hold circuit;
sampling and holding a third pixel signal from a pixel in an even pixel row in a sample and hold circuit;
charging said pixel with a pixel reset signal;
sampling and holding a fourth pixel signal from said pixel in said sample and hold circuit;
comparing said first pixel signal with a threshold signal, wherein said comparison is used determine if said first signal exceeds a threshold signal;
outputting said first and second pixel signals to an amplifier if said first signal exceeds said threshold voltage;
if said first signal does not exceed said threshold signal, combining said first and third pixel signals to produce a first averaged pixel signal and combining said second and fourth pixel signals to produce a second averaged pixel signal, said first and second signals outputted to an amplifier as differential inputs to said amplifier; and
repeating said method for performing a progressive readout until each pair of an odd pixel row and adjacent even pixel row in said pixel array are processed. - View Dependent Claims (29, 30, 31)
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32. A method of operating a pixel array comprising:
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sampling a first pixel signal from a pixel in a first pixel row, said first pixel signal having a first integration period;
sampling a first pixel reset signal from said pixel in said first pixel row;
sampling a second pixel signal from a pixel in a second pixel row, said first pixel signal having a first integration period and said second pixel row is adjacent to said first pixel row;
sampling a second pixel reset signal from said pixel in said second pixel row; and
selectively using a combination of pixel signals to produce an output signal, said signals comprising said first sampled pixel signal and said first pixel reset signals as well as said second sampled pixel signal and said second pixel reset signal. - View Dependent Claims (33, 34, 35, 36, 37, 38)
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39. A method of operating a pixel array comprising:
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sampling a first pixel signal from a first pixel row from said array, said first pixel signal having a first integration period;
selectively sampling a second pixel signal from a second pixel row adjacent to said first pixel row, said second pixel signal having a second integration period different from the first integration period; and
selectively using said pixel signals to produce an output signal. - View Dependent Claims (40, 41, 42)
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Specification