Active pixel sensor array with multiresolution readout
DCFirst Claim
1. A multiresolution imaging device comprising:
- a focal plane array of CMOS active pixel cells monolithically formed on a semiconductor substrate, wherein each of the cells includes a photosensing element operable to generate electrical charge in response to an image scene, a charge coupled device section adjacent to said photosensing element having a sensing node and a charge coupling stage for transferring said charge from said photosensing element to said sensing node, a readout circuit connected to said sensing node and configured to have at least one output transistor for producing an image signal output indicative of said image scene; and
a multiresolution circuit formed on said substrate, connectable to each one of said cells for processing the image signal output from each one of a group of cells forming a contiguous block within the array and operable to vary a number of cells in said contiguous block to produce different output resolutions.
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Abstract
An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node. There is also a readout circuit, part of which can be disposed at the bottom of each column of cells and be common to all the cells in the column. The imaging device can also include an electronic shutter formed on the substrate adjacent the photogate, and/or a storage section to allow for simultaneous integration. In addition, the imaging device can include a multiresolution imaging circuit to provide images of varying resolution. The multiresolution circuit could also be employed in an array where the photosensitive portion of each pixel cell is a photodiode. This latter embodiment could further be modified to facilitate low light imaging.
439 Citations
22 Claims
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1. A multiresolution imaging device comprising:
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a focal plane array of CMOS active pixel cells monolithically formed on a semiconductor substrate, wherein each of the cells includes a photosensing element operable to generate electrical charge in response to an image scene, a charge coupled device section adjacent to said photosensing element having a sensing node and a charge coupling stage for transferring said charge from said photosensing element to said sensing node, a readout circuit connected to said sensing node and configured to have at least one output transistor for producing an image signal output indicative of said image scene; and a multiresolution circuit formed on said substrate, connectable to each one of said cells for processing the image signal output from each one of a group of cells forming a contiguous block within the array and operable to vary a number of cells in said contiguous block to produce different output resolutions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A multiresolution imaging device comprising:
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a focal plane array of CMOS active pixel cells monolithically formed on a semiconductor substrate and arranged relative to one another in rows and columns, wherein each of the cells includes a photosensing element operable to generate electrical charge in response to an image scene, a charge coupled device section adjacent to said photosensing element having a sensing node and a charge coupling stage for transferring said charge from said photosensing element to said sensing node, a readout circuit connected to said sensing node and configured to have at least one output transistor for producing an image signal output indicative of said image scene; a multiresolution circuit formed on said substrate, connectable to each cell for processing the image signal output from each one of a group of cells forming a contiguous block within the array and operable to vary a number of cells in said continuous block to produce different output resolutions, wherein the multiresolution circuit is capable of being simultaneously connected to at least two cells in a row of the array and comprises; a column averaging element, operating to combine and average the image signal outputs from a predetermined number of consecutive cells within the row of the array, wherein said predetermined number of consecutive cells constitutes a row of a block of cells and said combining and averaging produces an average for the row of the block; and a row averaging element comprising, a storage element operable to receive and store averages for consecutive rows of the block of cells from the column averaging element, and a processing element operable to combine and average said stored averages, thereby producing a block average. - View Dependent Claims (10)
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11. An image device, comprising:
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a focal plane array of pixel cells wherein each cell responds to an input image and has a sensing node which outputs an image signal; a multiresolution circuit connectable to each one of said cells for processing the image signal output from each one of a group of cells forming a contiguous block within the array; a block average element configured to combine and average signals from said block to produce a block average; a reset element connected to each sensing node and configured to periodically reset a potential of said sensing node to a predetermined potential to produce a reset signal from said sensing node; a reset average element configured to combine and average the reset signals from the cells forming said block to produce a block reset average; a comparing element configured and connected to differentially compare the block average and the block reset average to produce a differential block average; and an output element connected to output a signal representative of the differential block average.
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12. An imaging device comprising:
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a focal plane array of CMOS active pixel cells monolithically formed on a semiconductor substrate, wherein each one of the cells includes a photosensing element operable to generate electrical charge in response to an image scene, a charge coupled device section adjacent to said photosensing element having a sensing node and a charge coupling stage for transferring said charge from said photosensing element to said sensing node, a readout circuit connected to said sensing node and configured to have at least one output transistor for producing an image signal output indicative of said image scene; and a multiresolution circuit interconnecting adjacent photosensing elements so as to form a contiguous block within the array and produce a combined output image signal, said combined output image signal representing an average of the image signals output by each of the photosensing elements in the block. - View Dependent Claims (13, 14)
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15. A low light imaging device comprising:
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a monolithic semiconductor integrated circuit substrate; a focal plane array of CMOS active pixel cells formed on said substrate, each one of said pixel cells comprising, a photodiode formed within the substrate, a floating diffusion disposed and configured to receive electrical charge from said photodiode, a readout circuit connected to the floating diffusion, and a transfer gate overlying the substrate between said floating diffusion and the photodiode; and interconnecting circuit operating to interconnect adjacent photodiodes so as to form a contiguous block within the array. - View Dependent Claims (16, 17)
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18. A method of performing multiresolution imaging comprising:
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providing a focal plane array of CMOS active pixel cells formed on a monolithic substrate, each cell including a photosensing element, a charge coupled device section adjacent to said photosensing element having a sensing node and a charge coupling stage for transferring electrical charge from said photosensing element to said sensing node, a readout circuit connected to said sensing node and configured to have at least one output transistor; using said array to capture an image scene; connecting a group of cells to form a contiguous block within the array; combining and averaging image signals output from the cells forming said block to produce a block average; and
,outputting a signal representative of the block average. - View Dependent Claims (19, 20, 21, 22)
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Specification