| 摘要 |
PURPOSE:To regenerate pictures including half tones, by setting plural reference voltages to detect the densities of pictures and selecting and using repetitively the reference voltages in a period shorter than the period of each scanning. CONSTITUTION:A reference voltage generating circuit 13 for the reference voltage VTH2 is provided in parallel to a reference voltage generating circuit 12 for the reference voltage VTH1. The output of these two circuits are fed to an analog multiplexer 24. The multiplexer 24 delivers the voltage VTH1 when the output 30a of an exclusive OR circuit 30 is set at a high level and delivers the voltage VTH2 when the output 30a is set at a low level respectively. In such constitution of circuit, a binary picture signal 15 which is binary coded by a binary coding circuit 14 is delivered at the area of the multiplexer 24 since the voltage VTH1 or VTH2 is selected and delivered by the control signal sent from the circuit 30 and in a period shorter than the period of a scanning. |
