| 摘要 |
PURPOSE:To improve the detecting performance for jams by disposing a sensor unit wherein plural pieces of light emitting elements and one photodetector are combined to one body in proximity to the surface of a photoreceptor in the position after separation of recording paper. CONSTITUTION:An IR light emitting diode 20b for detecting toner density, a visible light emitting diode 20c for detecting jams, and a phototransistor 20d which detects the light emitted from the diodes 20b, 20c and reflected from a small piece for reference density and outputs as electric signals are embedded respectively at prescribed angles in a supporting body 20a for forming a sensor unit 20. Then the space for mounting and the number of constituting parts are reduced and since visible light is used for detection of jams, the difference in the output levels of the photodetector when a jam is detected changes largely as compared to the case in which IR is used, whereby the detecting performance for jams is improved. |
