Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1985-12-05
1987-06-16
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
358293, H04N 110
Patent
active
046738118
ABSTRACT:
A variable threshold scan detector for use in raster output scan (ROS) systems, whereby the input scanning beam intensity is continually monitored and the threshold is set at a percentage of the signal value. Feedback from a peak detector circuit adjusts the threshold voltage to approximately 55 percent of the peak voltage. When the signal voltage exceeds the threshold voltage, the crossover circuit is enabled and a scan pulse is generated when crossover is detected. The scan detector ignores noise signals below the threshold voltage.
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patent: 4412331 (1983-10-01), Chapman
IBM Tech. Discl. Bull.; "Multi-Function Auto Thresholding Algorithm"; Wong; vol. 21, No. 7; Dec. 1978; pp. 3001-3003.
IBM Tech. Discl. Bull.; "Dynamic Video Thresholding"; H. Kleep; vol. 22, No. 3; Aug. 1979; pp. 1031-1033.
Xerox Discl. Journal; "Adaptive Binariser"; Tandon et al., vol. 6, No. 5; Sep./Oct. 1981; pp. 283-286.
Allen S.
Nelms David C.
Weiss Franklyn C.
Xerox Corporation
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