| 摘要 |
PURPOSE:To improve directivity between a light emitting element and a light receiving element and then to improve sensor sensitivity by providing pin holes on the front surfaces of the light emitting element and light receiving element. CONSTITUTION:This device is provided with the light emitting element 1 irradiating a photosensitive body with light and the light receiving element 2 detecting the light reflected by the photosensitive body to detect the optical density on the surface of the photosensitive body from the quantity of the received light and to control the density. In this case, the pin holes 4 and 5 are provided on the front surfaces of the light emitting element 1 and light receiving element 2. Namely, the photosensitive body is irradiated with light from the light emitting element 1 via the pin hole 4 provided on a light shielding plate 3, and the reflected light is received by the light receiving element 2 via the pin hole 5. Thus, directivity is improved, thereby raising sensor sensitivity. |
