Exposure control for image sensors
First Claim
Patent Images
1. A pixel array comprising:
- a plurality of pixels, each of said plurality of pixels comprising;
a photosensor for converting incident light into a charge,a plurality of transistors, coupled to said photosensor, for controllably resetting said photosensor and transferring said charge to an output node, andan antiblooming transistor arranged to take an antiblooming current from said photosensor; and
a control circuit for supplying a supply voltage to the antiblooming transistor of the at least one pixel and for disconnecting said supply voltage from the antiblooming transistor and connecting the antiblooming transistor to supply a signal to an exposure control circuit during an integration period of said photosensor, the exposure control circuit arranged to control exposure of light to the pixel photosensors.
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Abstract
An imaging system utilizes an exposure control circuit to control the length of an exposure in full frame mode. The exposure control circuit receives as an input the antiblooming current from at least a representative sample of pixels and determines when to end an exposure based on the amount of current received.
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Citations
10 Claims
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1. A pixel array comprising:
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a plurality of pixels, each of said plurality of pixels comprising; a photosensor for converting incident light into a charge, a plurality of transistors, coupled to said photosensor, for controllably resetting said photosensor and transferring said charge to an output node, and an antiblooming transistor arranged to take an antiblooming current from said photosensor; and a control circuit for supplying a supply voltage to the antiblooming transistor of the at least one pixel and for disconnecting said supply voltage from the antiblooming transistor and connecting the antiblooming transistor to supply a signal to an exposure control circuit during an integration period of said photosensor, the exposure control circuit arranged to control exposure of light to the pixel photosensors. - View Dependent Claims (2, 3)
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4. A method for operating a pixel, comprising:
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supplying a supply voltage to a pixel node capable of receiving a signal from a integrating photosensor; isolating the supply voltage from the node and connecting the node to an exposure control circuit during a period when said photosensor is integrating; and controlling light exposure of said pixel by said exposure control circuit based on a signal supplied by said node.
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5. A pixel for an imaging system, comprising:
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a photosensor for converting incident light into a signal, and having a photosensor output for said signal; a plurality of transistors, coupled to said photosensor output, for controllably resetting and transferring said signal to a pixel output node; an antiblooming transistor arranged to gate an antiblooming signal from the photosensor output to an antiblooming node; and a circuit for coupling said antiblooming node to a supply voltage and disconnecting said antiblooming node from said supply voltage during an integration period of the pixel photosensor. - View Dependent Claims (6)
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7. An imaging device, comprising:
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a pixel array having a plurality of pixels arranged in rows and columns, each pixel of the array comprising; a photosensor for integrating charge in response to receiving light; a storage node for receiving charges from the photosensor; a reset transistor responsive to a reset select signal for resetting said storage node with a supply voltage, the reset transistor having a first node selectively coupled to the supply voltage and a second node coupled to the storage node; and a readout circuit for providing an output voltage to a column line based on charges stored at said storage node; and an exposure control circuit arranged to control exposure of light to the pixel photosensors, said exposure control circuit receiving a signal from said first node of at least one pixel when said first node is uncoupled from said supply voltage during a period when said photosensor of said at least one pixel is integrating charge. - View Dependent Claims (8, 9, 10)
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Specification