Higher dynamic range image sensor with signal integration
First Claim
Patent Images
1. An apparatus, comprising:
- a comparator;
an image sensor coupled to an input of said comparator, wherein the output of said comparator is triggered in the event a voltage of said image sensor meets and/or exceeds a threshold voltage;
a counting circuit coupled to an output of said comparator, said counting circuit comprising a capacitor to be charged in proportion to a number of times the comparator is triggered by said image sensor, wherein said counting circuit comprises a lower range counting circuit and a higher range counting circuit;
wherein an output signal, representative at least in part of a light signal detected by said image sensor, is based at least in part on a voltage of the capacitor and a charge on the image sensor.
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Abstract
Briefly, in accordance with one embodiment of the invention, a higher dynamic range image sensor may be implemented by comparing a voltage across the sensor to a threshold voltage during image capture. At the threshold voltage, a count may be registered and the image sensor may be reset for continued image capture until an exposure is complete. A final image signal may be obtained by multiplying the threshold voltage by the number of counts registered and adding the final image sensor voltage.
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Citations
24 Claims
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1. An apparatus, comprising:
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a comparator; an image sensor coupled to an input of said comparator, wherein the output of said comparator is triggered in the event a voltage of said image sensor meets and/or exceeds a threshold voltage; a counting circuit coupled to an output of said comparator, said counting circuit comprising a capacitor to be charged in proportion to a number of times the comparator is triggered by said image sensor, wherein said counting circuit comprises a lower range counting circuit and a higher range counting circuit; wherein an output signal, representative at least in part of a light signal detected by said image sensor, is based at least in part on a voltage of the capacitor and a charge on the image sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method, comprising:
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comparing a voltage of an image sensor to a threshold voltage; registering a count when the voltage of the image sensor meets and/or exceeds a threshold voltage, said registering comprising counting over a lower range of counts with a first counting circuit and counting over a higher range of counts with a second counting circuit; resetting the image sensor when a count is registered; continuing with said comparing, said registering, and said resetting until an exposure is complete; and providing an output voltage representing a number of counts, and a voltage of the image sensor. - View Dependent Claims (10, 11, 12)
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13. An apparatus, comprising:
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means for comparing a first input with a second input; means for providing a voltage in response to a light signal, said voltage providing means being coupled to the first input of said comparing means, wherein an output of said comparing means is triggered in the event a voltage of said voltage providing means meets and/or exceeds a threshold voltage applied to the second input of said comparing means; and a means for accumulating a charge, said charge accumulating means being coupled to the output of said comparing means, wherein said accumulating means accumulates a charge proportional to a number of times said comparing means is triggered by said voltage providing means, wherein said accumulating means comprises a lower range accumulating means and a higher range accumulating means; wherein an output signal, representative at least in part of a light signal detected by said voltage providing means, is based at least in part on a charge accumulated by said accumulating means and a voltage of said voltage providing means. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. An apparatus, comprising:
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means for comparing a voltage of an image sensor to a threshold voltage; means for registering a count when the voltage of the image sensor meets and/or exceeds a threshold voltage, said registering means comprising first counting means for counting over a lower range of counts and second means for counting over a higher range of counts; means for resetting the image sensor when a count is registered; and means for providing an output voltage representing a number of counts, and a voltage of the image sensor. - View Dependent Claims (22, 23, 24)
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Specification