| 摘要 |
PURPOSE:To enable exposure by optimum quantity of light at all times by detecting the quantity of light and controlling the quantity of current to a light source for exposure. CONSTITUTION:Irradiated light for exposure by a lamp 3 of a light source for original exposure is reflected by the back face of a standard white plate 6 shifted by a platen and received by a photodiode 22, and the quantity of light for exposure is detected through an operational amplifier 32 and an A/D converter. An average value of the result of detection based on sampling of five times etc. is calculated by a microcomputer 34 and supplied through a D/A converter 35-2, and the threshold value of a PWM modulator 38 is controlled. Thus, the duty ratio of current supply to the lamp 3 is changed, and the quantity of light for exposure can be optimized at all times. |
