| 摘要 |
PURPOSE:To set a proper exposure quantity exactly, by increasing or decreasing the quantity of light of an exposure quantity display lamp in accordance with a light quantity set value of an exposure quantity setting device, and visibly displaying the light quantity set value. CONSTITUTION:When reference voltage from a reference voltage generating circuit 28 is varied by slide-operating a light quantity setting controll 11, difference voltage outputted from an error amplifier 27 is also varied. Accordingly, pulse generating phase of a trigger pulse generating circuit 31 is varied, a conducting angle of a thyristor 24 is also varied, and the quantity of light of a lamp 19 is increased or decreased. As a result, brightness according to a light quantity set value by the light quantity setting control 11 is displayed on a light quantity display part 13. Subsequently, an electronic copying machine starts its copying operation, an exposure lamp 24 is lighted at a phase angle corresponding to the lamp 19, and the exposure is executed. According to such a constitution, the proper exposure quantity is set exactly, since it is set while watching the light quantity display part 13. |
