| 摘要 |
PURPOSE:To enable minituarization and cost reduction of a device to be performed by making a size of a light emission element small, by a method wherein the light emission element has an image density of not less than a specific value and, besides, a projection means for projecting a light image by the light emission element on an image carrier by magnification. CONSTITUTION:A LED array 9 is arranged parallel to a drum 7 in a lengthwise direction of the photosensitive material drum 7, and its length is fairly shorter than that of the photosensitive material drum 7. Therefore, an effective image width at the photosensitive material drum 7 is illuminated by using a projection lens 10. In that case, a length of the LED array to be used is determined by a pixel density, i.e. the number of PEL necessary at the photosensitive material drum 7, the number of PEL at the LED array 9, and a magnification of the projection lens. That is, the system is constructed as follows: the LED array having the number of PEL larger than that necessary on the photosensitive material drum 7 is used, the image is magnified with the projection lens 10, is projected on the photosensitive material drum 7, and the number of PEL required on the drum can be obtained. Therefore, a size of the LED array to be used can be miniaturized. |
