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US 7,397,505 B2Granted
CMOS sensor with over-saturation abatement
AssigneeZoran Corporation
InventorsKevin E. Brehmer, Brannon Harris
Life of this patent
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Abstract
A method and apparatus are described that detect and correct for over-saturation lighting conditions in a CMOS Image Sensor.
Claims8
A method for image sensing comprising the acts of:
- producing, from a photo detector, a plurality of detected electronic signals responsive to an optical image;
- amplifying, with a column buffer amplifier, signals selected from the detected electronic signals to produce a plurality of amplified signals;
- sampling, with a correlated double sampler, signals selected from the amplified signals to produce a plurality of sampled signals;
- and
- clamping, by a clamp circuit, at least one signal selected from the sampled signals during a reset phase of the correlated double sampler in response to a detecting of at least one over-saturation condition, whereby image inversion is at least partially abated.
2 more elements
In an image sensor that correlates a reset sample of a first signal during a first interval after reset of a photo detector for a pixel and a second sample of the first signal during a later interval in the same sampling cycle as the first interval to produce a luminance signal for said pixel, a method comprising:
- detecting that the first signal is slewing excessively rapidly during the first interval;
- and
- in response to said detecting, limiting the value of the reset sample;
- whereby the image sensor produces an output of improved accuracy by abating an error in the luminance signal for said pixel due to said excessively rapid slewing, wherein the error is an image inversion due to over-saturation.
1 more element
A method of image sensing, comprising:
- determining a reset sample of a first signal during a first interval after reset of a pixel in a photo detector;
- determining a second sample of the first signal during a later interval in the same sampling cycle as the first interval;
- correlating the reset sample and the second sample to produce a luminance signal for said pixel;
- detecting that the first signal is slewing excessively rapidly during the first interval;
- and in response to said detecting, limiting the value of the reset sample, whereby image inversion is at least partially abated.
2 more elements
Dependencies are inferred from the claim text.