| 摘要 |
PURPOSE:To stably obtain the most suitable light quantity from a light source, by detecting the emitting light quantity of the light source and outputting a period signal corresponding to the emitting light quantity, and then, controlling the power supply to the light source in accordance with the period signal. CONSTITUTION:As shown in the figure, a short-focussing lens array 13 and reflecting light detecting element 16 are positioned. Positioning of each section is made in the figure so that the slit width (a) of the lens array 13 and the slit width (b) of an ABC sensor 16 become equal to each other. When each section is positioned as shown in the figure, a prescribed distance corresponds to the (a)(=b). That is to say, light made incident on the ABC sensor 16 is from an area which is farther from the area of an optical image introduced onto a photosensitive body by the lens array 13 by a distance (a), and ones preceding in time. Therefore, the present emitting light quantity of a fluorescent lamp 19 is determined based on a reference light quantity data obtained immediately before and a reference light quantity by presently detecting reflecting light sets the immediately after emitting light quantity. Accordingly, exposure to an original is made with a light quantity corresponding to the density of the original at the exposure position. |
