Detector in an image read-out system

摘要

A photo-sensor, such as a photo-diode, is applied to the converging area of a flat type light transmission unit in an image read-out system, thereby intercepting a part of the scan light which falls on and travels through the light transmission unit after being reflected from an image-bearing sheet. The output signal from the photo-sensor can be advantageously used to detect arrival of the sheet edge at the scanning station, any scratches on the sheet and other operating conditions as required.