Title:
PHOTOELECTRIC DETECTOR
Document Type and Number:
Japanese Patent JPS60150630
Kind Code:
A
Abstract:
PURPOSE:To shorten the detection time while simplifying the constitution of the titled device by a method wherein the detection signals on a detection regional surface are utilized as synchronous signals of pattern signals as well as a threshold voltage of signal detection. CONSTITUTION:A photoreceiving surface 18a on the central part of a photodetector 18 outputs signals informing an amplifier 51 of the status that scanning beams for detection are scanning of a detection region whenever it is detected. The amplifier 51 outputs the amplified signals to a voltage comparator 58 and an A/D converter 54. The signals on a photoreceiving surface 18a outputted to the A/D converter 54 are converted into digital signals to be transmitted to a processing circuit 57. The level of signals from the first time scanning beams inputted in the processing circuit 57 is detected by the circuit 57 to be outputted to a D/A converter 53 after deciding the threshold level by processing. This threshold voltage is utilized as the reference voltage of the voltage comparator 58. This voltage comparator 58 compares the output of the amplifier 51 by the second time scanning beams with the reference voltage to output signals while the scanning beams for detection are scanning on the detection region.
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Inventors:
HIRAGA RIYOUZOU
YOMODA MINORU
YOMODA MINORU
Application Number:
JP563784A
Publication Date:
August 08, 1985
Filing Date:
January 18, 1984
Export Citation:
Assignee:
CANON KK
International Classes:
H01L21/30; G01S7/481; G01S7/491; G03F9/00; H01L21/027; (IPC1-7): G03F9/00
Attorney, Agent or Firm:
Wakabayashi Tadashi