| 摘要 |
PURPOSE:To obtain stable copy images of always good quality by sensing the increase or decrease in the quantity of light and opening and closing of the iris of optical path. CONSTITUTION:The photo sensor A which receives the quantity of light from a fluorescent lamp 2 being a light source passing an optical path 1 is disposed in the position deviated from the image range on the side part of the optical path 1 and is connected to the bimetal heater 17 heating the bimetals B connected by means of wires to the operating ring 22 of the optical path aperture plate C. Then, when the fluorescent lamp 2 is lighted, the photo sensor A senses the quantity of light and lowers its resistance value, causing the bimetal heater 17 to evolve heat and the operating ring 22 to turn, thereby turning the apeature plate C in the close direction. When copying continues and the quantity of light increases or decreases upon elevating or lowering of the tube wall temperature of the fluorescent lamp 2, the aperture plate C opens or closes to perform light quantity increasing or decresing action, thus the quantity of light is maintained always constant irrespective of the using time and using method of the copying machine and the intended object is achieved. |
