| 摘要 |
<p>PURPOSE:To correct an error caused by variance of a light emitting element and a light receiving element and to prevent erroneous detection of an original size by deciding an analog output level of the light receiving element to detect the original size, and freely changing its deciding level. CONSTITUTION:The title device is provided with the light emitting element 5 which irradiates the original 6, the light receiving element 7 which receives a reflected light coming from the original 6 and an original size detecting means 3 which detects the size of the original 6 according to the output of the light receiving element 7. In addition, the original size detecting means 3 is decided the analog output level of the light receiving element 7, to detect the size of the original 6, and to change its deciding level. Therefore, even when a gain on the light receiving element side is fixed, the error caused by different characteristics of the light emitting element 5 and light receiving element 7 can be corrected. In this case, when the deciding level is changeably set in an operation part, the error is more easily corrected, and erroneous detection caused by a disturbed light can be prevented.</p> |
