| 摘要 |
PURPOSE:To obtain a binary coded output faithful to information of an original, by forming a comparing signal with a picture signal having deteriorated contrast. CONSTITUTION:Irregularly reflected light from the original 4 is received at an image sensor 9 via an optical system and photoelectric converted. On the other hand the reflected light reflected on a half mirror 7 partly is reflected on a full reflecting mirror 8 and received on an image sensor 10. Since a lens 6 is adjusted so as to be focused on a photodetecting plane of the sensor 9, the reflected light is not focused on the photodetecting plane of the sensor 10. An output picture photoelectric converted at the sensor 9 is a continuous video signal at a sample holding circuit 11 and inputted to a plus terminal of a comparator 15. Further, the picture signal photoelectric converted at the sensor 10 is superimposed with a DC voltage E0 through a sample holding circuit 12 and inputted to a minus terminal of the comparator 15. A waveform of a reference signal input 14 of this comparator 15 is deteriorated in contrast more than the picture signal. The comparator 15 binary-codes the picture signal with this voltage taken as a threshold value and a binary coded signal faithful to the picture signal is obtained at a terminal 16. |
