Patent ID: 7551195

Claim:
A light scanning device, comprising: a light emitting system configured to emit a light beam to be scanned; a light scanning system configured to deflect the light beam emitted from the light emitting system to scan the light beam on a photosensitive surface; a light receiving system configured to receive the light beam and output a light receiving signal; and a synchronizing signal generating system configured to generate a synchronizing signal with which light scanning performed by the light scanning system is synchronized, wherein the synchronizing signal generating system divides the light receiving signal into two light receiving signals and includes: a first bias superimposing system configured to superimpose a first bias signal onto one of the two light receiving signals to generate a first light receiving signal of the two light receiving signals; a second bias superimposing system configured to superimpose a second bias signal with a different level from the level of the first bias signal onto the other of the two light receiving signals to generate a second light receiving signal of the two light receiving signals; a waveform shaping system configured to shape the waveform of the second light receiving signal; and a comparing system configured to compare the first light receiving signal with the second light receiving signal to output the synchronizing signal.