Method for temperature compensation of an image detector
First Claim
1. A method for temperature compensation of an image detector including photosensitive spots sensitive to ambient temperature, each connected to a row conductor and a column conductor, each of the photosensitive spots being connected by one conductor to a read circuit, wherein the photosensitive spots are divided into a) detecting photosensitive spots configured to be exposed to light information corresponding to the image to be detected, read circuits associated with the detecting photosensitive spots each delivering a measurement voltage representative of the image to be detected, and b) into blind photosensitive spots protected from the light information, read circuits associated with the blind photosensitive spots each delivering a dark voltage serving for temperature compensation, comprising:
- picking up, during detection of an image, the dark voltages;
generating an average correction value from the dark voltages coming from one or more detected images; and
using the average correction value to generate a correction voltage to be applied, during detection of a subsequent image, to the read circuits associated with the detecting photosensitive spots so that they deliver a measurement voltage made substantially independent of temperature.
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Abstract
A method and device for temperature compensation of an image detector including photosensitive spots sensitive to ambient temperature, each connected to a row conductor and a column conductor. The photosensitive spots are connected by their conductors to a read circuit. The photosensitive spots are divided into detecting photosensitive spots to be exposed to light information corresponding to the image to be detected, the read circuits associated with these photosensitive spots each delivering a measurement voltage representative of the image to be detected, and into blind photosensitive spots protected from the light information, the read circuits associated with these blind photosensitive spots each delivering a dark voltage serving for temperature compensation. During detection of an image the dark voltages are picked up, then an average correction value from the dark voltages coming from one or more detected images is generated, and the average correction value is used to generate a correction voltage to be applied, during detection of a subsequent image, to the read circuits associated with the detecting photosensitive spots so that they deliver a measurement voltage made substantially independent of temperature. Such a method and device may find application in particular to radiological image detectors.
39 Citations
14 Claims
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1. A method for temperature compensation of an image detector including photosensitive spots sensitive to ambient temperature, each connected to a row conductor and a column conductor, each of the photosensitive spots being connected by one conductor to a read circuit, wherein the photosensitive spots are divided into a) detecting photosensitive spots configured to be exposed to light information corresponding to the image to be detected, read circuits associated with the detecting photosensitive spots each delivering a measurement voltage representative of the image to be detected, and b) into blind photosensitive spots protected from the light information, read circuits associated with the blind photosensitive spots each delivering a dark voltage serving for temperature compensation, comprising:
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picking up, during detection of an image, the dark voltages;
generating an average correction value from the dark voltages coming from one or more detected images; and
using the average correction value to generate a correction voltage to be applied, during detection of a subsequent image, to the read circuits associated with the detecting photosensitive spots so that they deliver a measurement voltage made substantially independent of temperature. - View Dependent Claims (2, 3, 4, 5, 6)
converting, in an analog-to-digital converter, the measurement voltages and dark voltages of the photosensitive spots; and
generating the average correction value from the digitized dark voltages, the average correction value serving to control a digital-to-analog converter that delivers the correction voltage to be applied to the read circuits associated with the detecting photosensitive spots.
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3. The method for temperature compensation of an image detector as claimed in claim 1, wherein the generating the average correction value includes a simple averaging over dark voltages coming from plural detected images.
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4. The method for temperature compensation of an image detector as claimed in claim 1, wherein the generating the average correction value includes a sliding averaging over the dark voltages coming from plural detected images.
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5. The method for temperature compensation of an image detector as claimed in claim 1, wherein in the generating the average correction value from dark voltages coming from one or more detected images, a time interval separating detection of an earliest image from detection of a most recent image used in the averaging is less than a thermal time constant of the detector.
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6. The method for temperature compensation of an image detector as claimed in claim 1, further comprising connecting the blind photosensitive spots to an outermost portion of at least one row conductor.
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7. A temperature-compensated image detector including photosensitive spots, each connected to a row conductor and a column conductor, each photosensitive spot being connected by one conductor to a read circuit, wherein the photosensitive spots are divided into a) detecting photosensitive spots, configured to be exposed to light information corresponding to the image to be detected, read circuits associated with the detecting photosensitive spots each delivering a measurement voltage representative of the image to be detected, and b) into blind photosensitive spots protected from the light information, read circuits associated with the blind photosensitive spots each delivering a dark voltage used for temperature compensation, comprising:
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means for picking up the dark voltages during detection of an image and for generating an average correction value from the dark voltages picked up coming from one or more detected images; and
means for generating, from the average correction value, a correction voltage configured to be applied to the read circuits associated with the detecting photosensitive spots, during detection of a compensated subsequent image, so that the detecting photosensitive spots deliver a measurement voltage made approximately independent of temperature. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification