CMOS sensor with over-saturation abatement
First Claim
Patent Images
1. 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 detected electronic signals and the sampled signals in response to a detecting of at least one over-saturation condition;
whereby image inversion is at least partially abated.
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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.
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Citations
26 Claims
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1. A method for image sensing comprising the acts of:
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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 detected electronic signals and the sampled signals in response to a detecting of at least one over-saturation condition;
whereby image inversion is at least partially abated. - View Dependent Claims (2, 3, 4)
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5. A method for enhancing a video image comprising the acts of:
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sampling a plurality of image signals with a correlated double sampler to produce a plurality of sampled signals;
clamping, with a clamp circuit, signals selected from the image signals and the sampled signals during a reset phase of the correlated double sampler. - View Dependent Claims (6, 7, 8, 9)
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10. A circuit comprising:
an image sensor array comprising;
a clamp circuit;
a column buffer amplifier; and
a correlated double sampling circuit. - View Dependent Claims (11, 12)
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13. A method for processing a signal comprising:
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producing a plurality of output luminance signals responsive to an incident light;
generating a first sample of one of the luminance signals at a first time and a second sample of the respective luminance signal at a second time;
producing a threshold passed signal output responsive to a condition of over-saturation by the incident light; and
clamping the respective luminance signal sample during the first time responsive to the threshold passed signal. - View Dependent Claims (14, 15)
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16. A circuit for providing a signal comprising:
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a plurality of pixel cells having a plurality of output luminance signals responsive to an incident light;
a correlated double sampler operative to generate a first sample of one of the luminance signals at a first time and a second sample of the respective luminance signal sample at a second time;
a threshold detection circuit having a threshold passed signal output responsive to a condition of one of the pixel cells of being over-saturated by the incident light; and
a clamp circuit wherein the clamp circuit clamps the respective luminance signal during the first time responsive to the threshold passed signal. - View Dependent Claims (17, 18, 19)
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20. A circuit for providing a signal comprising:
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a means for producing a plurality of output luminance signals responsive to an incident light;
a means for generating a first sample of one of the luminance signals at a first time and a second sample of the respective luminance signal at a second time;
a means for producing an over-saturation signal output responsive to a condition of over-saturation by the incident light; and
a means for clamping the respective luminance signal sample during the first time responsive to the over-saturation signal. - View Dependent Claims (21, 22, 23)
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24. In an image sensor that correlates a first sample of a first signal during a first interval after reset of a photo detector and a second sample of the first signal during a later interval to produce a luminance signal, a method for abating an error in the luminance signal due to excessively rapid slewing of the first signal during the first interval wherein the improvement comprises:
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detecting that the first signal is slewing excessively rapidly during the first interval; and
limiting the value of the first sample;
whereby the image sensor produces an output of improved accuracy. - View Dependent Claims (25, 26)
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Specification