Light scanning unit, method of detecting failure of synchronization signal, and electrophotographic image forming apparatus using light scanning unit

摘要

A light scanning unit, a method of detecting a failure of a synchronization signal, and an electrophotographic image forming apparatus using the light scanning unit are provided. The light scanning unit includes a synchronization sensor which receives a portion of a light beam that is emitted from a light source and then deflected and scanned from a light deflector, to detect a horizontal synchronization signal. A width of a light-receiving surface of the synchronization sensor in a main scanning direction varies along a sub scanning direction. The light scanning unit having the above-described structure determines a high quality or a failure of a synchronization signal by using a width of a horizontal synchronization signal detected in a test operation.