Title:
CCD OUTPUT LEVEL CONTROL CIRCUIT
Document Type and Number:
Japanese Patent JPS6481568
Kind Code:
A
Abstract:
PURPOSE:To reproduce an excellent picture by detecting an output level of a CCD photodetector, applying long/short control to an exposure time of CCD in response to the level fluctuation so as to make the CCD output constant thereby forming a picture signal at all times without being affected by the fluctuation of the light source. CONSTITUTION:A white face being a reference on a rear plate 3 prior to reading of an original 1 is read by the CCD 11, its output is subjected to A/D conversion 13 and the result is given to a picture signal processing circuit 14. Then the original face is read. The lighting luminous quantity of the light source 4 is detected by the CCD 11 to apply A/D conversion 13. It is detected by a maximum value detection circuit 15 and when the output of the circuit 15 is larger (smaller) than the upper limit of a window comparator 16, the window comparator 16 outputs an up-count output U (down count output D) to an up-down counter 17 to give the control signal to apply short/long exposure time to the CCD control circuit 12.
Inventors:
KUDO MITSURU
Application Number:
JP23958187A
Publication Date:
March 27, 1989
Filing Date:
September 24, 1987
Export Citation:
Assignee:
TOSHIBA CORP
International Classes:
H04N1/19; H04N1/04; H04N1/40; H04N1/407; (IPC1-7): H04N1/04; H04N1/40
Attorney, Agent or Firm:
Kazuo Sato (2 outside)