| 摘要 |
PURPOSE:To detect variations of the speed of a photosensitive body and allow the light emission timing of an LED array to be controlled, by employing a semi-conductor light emitting diode array with light receiving elements arranged on a light source substrate. CONSTITUTION:Light receiving elements 8 are arranged on a substrate 2 supporting an LED array chip 1. Light emitting from an LED chip 7 is focused on an encoder section 6 on a photosensitive drum passing through a focusing lens array 4. This encoder 6 is composed of a high reflection factor section and a low reflection factor section, and its light and darkness section is formed in the rotating direction of the photosensitive drum. The single period of light and darkness is equal to the interval of angular dots or an integral multiple of the interval. An image is focused on the photosensitive body drum by the LED array. The reflected beam from the encoder 6 is guided to the light receiving elements 8 passing through the image focusing lens array 4. Thus, a signal synchronized to the rotation of the photosensitive body drum is obtained. |
