| 摘要 |
PURPOSE:To always obtain an optimum picture density, and to prevent an undesired variation of the picture density caused by aging, etc. by detecting the picture density and controlling so as to obtain a picture corresponding to an adjusting signal set by a manual operation. CONSTITUTION:A target value setting circuit 30 derives an adjusting signal of a copying density which becomes a target value depending on an output from a variable resistor 10, and this adjusting signal is inputted to an automatic exposing circuit 29. The circuit 29 leads out a control signal for obtaining a copying density corresponding to the adjusting signal, to a line 31 in response to an output of a photodetector 28 and the adjusting signal. Also, the line 31 is provided to an individual contact 33 of a changeover switch 32, an output of a variable resistor 8 is provided to the other individual contact 34, and an output from a common contact 35 is provided to a regulator 36 for adjusting a voltage of an exposing lamp 13. When the contact 35 conducts to the contact 33, the voltage of the lamp 13 is set by the resistor 10 irrespective of various original densities, and a copying density controlled by the circuit 29 is obtained. |
