Automatic contrast control system

Abstract

Abstract PURPOSE:To obtain a sharp reception picture, by detecting the width of an original set on an original feed stand and setting white level in always matching with the background color of the original through the result of said detection. CONSTITUTION:The original to be transmitted is set between the moving pieces 2, 2' of the original supply stand 1, the size of original is discriminated with the magnet 3, the reed switches 4-6 are ON according to the size of the original, and the data or original moved toward the arrow Y is read in with the lens 7 and reader 8. The video signal read in with this reader is fed to the input terminal 11 and it is fed to the circuit B of ABC circuit ABC after being amplified at the transistor TR20 of the circuit B. The reference white level of input of input signal with the transistor TR20 during ABC favorable period, and TR23 is controlled with the output of switches 4-6 input to the input terminal 25-27 of the control circuit C when the ABC effective plan is achieved. Further, the white level of TR20 is always set in matching with the color of original, allowing to output the sharp detection signal from the binary coded circuit D.

Inventors

• 👤 Koichi Kohitsu
• 👤 Mitsuo Togashi
• 👤 Hideyuki Hanaoka
• 👤 Hajime Takayama

Bibliographic Details