PHOTOSENSOR AND IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To provide a photosensor having a configuration with the stability of an output value for calibration secured so that reliability and stability of calibration operation is improved. SOLUTION: The photosensor is provided with a reflection plate for calibration 14 for calibrating sensitivity and an optical path for calibration L3 for calibrating sensitivity inside the sensor, so that the positional relation of a light-emitting element 11, a light-receiving element 12 and the reflecting plate for calibration 14 is fixed. Thus, the stability of the output value for calibration can be secured, to improve the reliability of sensitivity calibration operation. An optical functional element 13 capable of switching the transmission/interception of light by the application of a voltage is installed in the optical path for calibration. The optical functional element is controlled into a light transmission state, when the calibration operation is performed and into a light interception state, when the calibration operation is not performed, so that the light cannot pass through the optical path for calibration L3, except when calibration operation is performed. Thus, extra operation work, such as, the separation of the influence of reflected light for calibration from the output value in normal detection becomes unnecessary. COPYRIGHT: (C)2009,JPO&INPIT