Active pixel sensor with mixed analog and digital signal integration
First Claim
Patent Images
1. A method of operating a CMOS image sensor, the method comprising:
- exposing an array of active pixels of the CMOS image sensor to an image;
reading out a first group of pixel analog signals from the array of pixels, while the pixels continue to generate charge from the exposure to the image, to generate a first group of circuitry analog signals associated with a first exposure of the pixels to the image;
converting the first group of circuitry analog signals into a corresponding first group of digital signals associated with the first exposure of the pixels to the image;
storing the first group of digital signals;
reading out a second group of pixel analog signals from the array of pixels, while the pixels continue to generate charge from the exposure to the image, to generate a second group of circuitry analog signals associated with a second exposure of the pixels to the image;
converting the second group of circuitry analog signals into a corresponding second group of digital signals associated with the second exposure of the pixels to the image;
storing the second group of digital signals;
combining the first group of digital signals with the second group of digital signals to produce a final group of digital signals representing the image;
storing the final group of digital signals; and
reading out the final group of digital signals.
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Abstract
An active pixel sensor includes mixed analog and digital signal integration on the same substrate. The analog part of the array forms the active pixel sensor, and the digital part of the array does digital integration of the signal.
26 Citations
40 Claims
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1. A method of operating a CMOS image sensor, the method comprising:
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exposing an array of active pixels of the CMOS image sensor to an image; reading out a first group of pixel analog signals from the array of pixels, while the pixels continue to generate charge from the exposure to the image, to generate a first group of circuitry analog signals associated with a first exposure of the pixels to the image; converting the first group of circuitry analog signals into a corresponding first group of digital signals associated with the first exposure of the pixels to the image; storing the first group of digital signals; reading out a second group of pixel analog signals from the array of pixels, while the pixels continue to generate charge from the exposure to the image, to generate a second group of circuitry analog signals associated with a second exposure of the pixels to the image; converting the second group of circuitry analog signals into a corresponding second group of digital signals associated with the second exposure of the pixels to the image; storing the second group of digital signals; combining the first group of digital signals with the second group of digital signals to produce a final group of digital signals representing the image;
storing the final group of digital signals; andreading out the final group of digital signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An imager comprising:
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an array of active pixels of a CMOS image sensor; a sampling circuit for reading out a first group of pixel analog signals from the array of pixels to generate a first group of circuitry analog signals associated with a first exposure of the pixels to an image and for reading out a second group of pixel analog signals from the array of pixels to generate a second group of circuitry analog signals associated with a second exposure of the pixels to the image, wherein the sampling circuit reads out the first and second group of pixel analog signals while the pixels continue to generate charge from exposure to the image; a converter for converting the first group of circuitry analog signals into a corresponding first group of digital signals associated with the first exposure of the pixels to the image and converting the second group of circuitry analog signals into a corresponding second group of digital signals associated with the second exposure of the pixels to the image; a memory for storing the first and second groups of digital signals; and a circuit for combining the first and second groups of digital signals to produce a final group of digital signals representing the image. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An imager comprising:
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an array of pixels disposed on a substrate; a first analog signal processor for processing a plurality of analog signals received from a first pixel in the array of pixels during an integration period of said pixel, wherein said pixel accumulates charge during said integration period and the first pixel is sampled multiple times during the integration period and during each sampling one of the plurality of analog signals is produced, said analog processor providing each of said plurality of analog signals as processed analog signals; a first circuit for converting each of said processed analog signals to digital signals; a first digital signal processor for receiving and processing said digital signals; and a first digital memory for storing said digital signals, wherein said digital signals are accumulated by said imager, the accumulation of which represents a digital integrated value for the integration period of the first pixel. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. A method of operating an imager comprising:
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capturing an image with a pixel sensor array during an integration period in which pixels in the array accumulate charge; causing said pixels in the array to each produce electrical signals representing said image; sampling said electrical signals for each pixel multiple times during said integration period; converting after every sampling said electrical signals for each pixel to digital signals; and accumulating and storing said digital signals for each pixel, said accumulated digital signals for each pixel representing a digital integrated signal for said integration period. - View Dependent Claims (28, 29, 30, 31, 32)
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33. An imager circuit comprising:
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an active pixel image sensor array; at least one circuit for sampling and converting analog information from a plurality of pixels in said array to digital values; at least one digital memory for storing and accumulating said digital values, wherein said plurality of pixels in said active pixel image sensor array are sampled multiple times during an integration period in which said plurality of pixels accumulate charge and each sampled value is stored and accumulated in said at least one digital memory, said accumulated values representing a respective integrated signal for each pixel during said integration period; and a controller for controlling the sampling of analog information from said pixels and said storage of digital values in said at least one digital memory. - View Dependent Claims (34, 35, 36, 37, 38)
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39. An imager comprising:
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an array of pixels disposed on a substrate; a first column analog double sampling circuitry for processing a plurality of analog signals received from a first pixel in the array of pixels during an integration period of said first pixel, wherein the first pixel is sampled multiple times during the integration period and during each sampling one of the plurality of analog signals is produced; a first converter for converting each of said processed analog signals from said first column analog double sampling circuitry to digital signals; a first digital signal processor for receiving and processing said digital signals; and a first digital memory for storing said digital signals, wherein said digital signals stored in said first digital memory are accumulated by said imager, the accumulation of which represents a digital integrated value for the integration period of the first pixel. - View Dependent Claims (40)
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Specification