| 摘要 |
PURPOSE:To prevent the surface of an original from being dirtied or the dirty caused by an optical system by attaching a detector to detect the color tone of the surface of the original and the quantity of reflected light projected from an exposure lamp on the original and controlling the developing bias voltage according to the output from the detector. CONSTITUTION:A color tone detector 90 composed of light emitting diodes and photodiodes is installed on a contact glass plate mounting an original to detect the color tone of the surface of the original. The light projected from an exposure lamp HLA and reflected by the original is detected by light detector 80 composed of photodiodes and so on to check the dirty of mirrors and lenses and deterioration of the exposure lamp. These outputs are converted by analog/digital converters 70 and 60 and inputted to a control circuit 50b to select a suitable developing bias voltage through a developing bias circuit 40 and apply the voltage to developing electrodes. Thus, the dirty surface of originals or dirty caused by the optical system is prevented and the excellect quality of picture is obtained. |
