| 摘要 |
PURPOSE:To control the quantity of exposure accurately by providing two light quantity sensors which differ in responsibility and switching sensor outputs between basic light quantity detection and original density detection. CONSTITUTION:The two light quantity sensors 12a and 12b are arranged nearby an optical path of exposure scanning behind a lens 11; the sensor 12a has such slow responsibility that a ripple of the phase control lighting of a light source lamp 4 is not detected and the sensor 12 has fast responsibility. This constitution uses the sensor 12a for basic light quantity control using a reference white plate 3 and makes corrections for deterioration in lamp ability, staining of an optical system, etc. Further, the sensor 12b is used by switching for original density detection to perform comparative arithmetic between original texture density and reference density, thereby performing exposure control. Consequently, the quantity of exposure is set accurately. |
