| 摘要 |
PURPOSE:To perform accurate exposure control, by arranging a photoelectric element at the rear of a mirror in an original exposure means to measure directly the quantity of light on the optical path. CONSTITUTION:The light of a lamp 10 is reflected by a mirror 12 and goes to an original 14, and the reflected light is exposed to a photosensitive drum through a lens. Before the reproduction starts the mirror 12 is rotated, and the illuminance of the lamp is measured by an photoelectric element 15 provided at the rear of the mirror 12. This measured value is compared with a reference voltage, and the thyristor firing angle of a lamp power source 11a (AC) is controlled in accordance with their difference. An amorphous silicon or an organic photoconductor is vapor-deposited or applied to the rear of the mirror 12 to form the photoelectric element 15 inexpensively with such a large area that the photoelectric element 15 can receive the light of the overall width of the original. |
