| 摘要 |
PURPOSE:To obtain a copy of constant density by operating the difference of output signals of the photodetecting element in case when the illumination source is turned on and off, varying the quantity of light of the illumination source in accordance with the operation value, and making a copy. CONSTITUTION:When the start of printing is commanded by the button 39, an output voltage signal of the photoelectric conversion element 31 is stored in the first memory circuit 33 by the output signal of the button 29. In this case, the lamp 3 is turned on, the element 31 generates an output voltage signal corresponding to the quantity of incident light by both the picture light and the external light, a signal is generated from the monostable multivibrator circuit 40, this signal is applied to the lamp driving circuit 38, the lamp 3 is turned off, and the output voltage signal of the element 31 is stored in the second memory circuit 34 by the output signal of the monostable multivibrator circuit 40. In this case, since the lamp 3 is turned off, the element 31 generates an output voltage signal corresponding to the quantity of incident light by the external light. When the output signal of the photoelectric conversion element is stored in the second memory circuit, the operation circuit 35 operates the difference between its voltage and the voltage stored in the first memory circuit 33. |
