Original Publication Date: 1980-Apr-30
Included in the Prior Art Database: 2004-Apr-02
Xerox Disclosure Journal
A simple and inexpensive paper sensor is disclosed. As shown in the drawing, the paper sensor comprises an infrared light-emitting diode (emitter) 12 and a photodetector 14, both bonded to a piece of glass 10 with transparent optical cement. The entire device is placed in the paper path 16 with the bottom surface 18 of the glass beveled or slanted so that it is slightly into the paper path to obtain a wiping action by the moving paper to keep the glass surface clean. The wedge shape of the glass, together with the lateral in-line placement of the emitter and photodetector, serve to prevent the reflection from the glass surface returning to the photodetector 14.