Electronic image sensor
First Claim
1. An electronic image sensor that can be adapted to operate at a predetermined normal frame rate or at frame rates lower than the predetermined normal frame rate, said sensor comprising:
- A. an array of photo-sensing pixel elements for producing image frames, each pixel element defining a photo-sensing region of said sensor and each pixel element comprising;
1) charge collecting circuits for collecting electrical charges produced in the photo-sensing region, and 2) a charge storage element for the storage of the collected charges;
B. charge sensing circuits for sensing the collected charges;
C. charge-to-signal conversion elements for converting charge values to electronic signals; and
D. timing elements for controlling the pixel circuits to produce image frames based on a master clock signal at the predetermined normal frame rate, defining a normal maximum per frame time, said timing elements comprising;
1) exposure adjustment circuits for setting per frame exposure times within a range of exposure times that include exposure times substantially longer than said normal maximum per frame time, 2) frame rate adjustment circuits that can be adapted to permit a decrease of the predetermined normal frame rate without adjusting the master clock signal.
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Accused Products
Abstract
An electronic imaging sensor. The sensor includes an array of photo-sensing pixel elements for producing image frames. Each pixel element defines a photo-sensing region and includes a charge collecting element for collecting electrical charges produced in the photo-sensing region, and a charge storage element for the storage of the collected charges. The sensor also includes charge sensing elements for sensing the collected charges, and charge-to-signal conversion elements. The sensor also includes timing elements for controlling the pixel circuits to produce image frames at a predetermined normal frame rate based on a master clock signal (such as 12 MHz or 10 MHz). This predetermined normal frame rate which may be a video rate (such as about 30 frames per second or 25 frames per second) establishes a normal maximum per frame exposure time. The sensor includes circuits (based on prior art techniques) for adjusting the per frame exposure time (normally based on ambient light levels) and novel frame rate adjusting features for reducing the frame rate below the predetermined normal frame rate, without changing the master clock signal, to permit per frame exposure times above the normal maximum exposure time. This permits good exposures even in very low light levels. (There is an obvious compromise of lowering of the frame rate in conditions of very low light levels, but in most cases this is preferable to inadequate exposure.) These adjustments can be automatic or manual.
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Citations
48 Claims
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1. An electronic image sensor that can be adapted to operate at a predetermined normal frame rate or at frame rates lower than the predetermined normal frame rate, said sensor comprising:
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A. an array of photo-sensing pixel elements for producing image frames, each pixel element defining a photo-sensing region of said sensor and each pixel element comprising;
1) charge collecting circuits for collecting electrical charges produced in the photo-sensing region, and 2) a charge storage element for the storage of the collected charges;
B. charge sensing circuits for sensing the collected charges;
C. charge-to-signal conversion elements for converting charge values to electronic signals; and
D. timing elements for controlling the pixel circuits to produce image frames based on a master clock signal at the predetermined normal frame rate, defining a normal maximum per frame time, said timing elements comprising;
1) exposure adjustment circuits for setting per frame exposure times within a range of exposure times that include exposure times substantially longer than said normal maximum per frame time, 2) frame rate adjustment circuits that can be adapted to permit a decrease of the predetermined normal frame rate without adjusting the master clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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Specification