Abstract: Provided is a device for detecting a horizontal synchronization signal of an image forming apparatus. The device includes a light intensity converter to convert light intensity of a first beam emitted from a first light source and light intensity of a second beam emitted from a second light source to be different from each other, and outputting the first and second beams; a photo detector to receive the first beam and the second beam output from the light intensity converter, and outputting a first signal having a first level at a time of receiving the first beam and a second level at a time of receiving the second beam; and a horizontal synchronization signal detector to detect a horizontal synchronization signal of the first beam and a horizontal synchronization signal of the second beam by using the first signal.

Abstract: Provided is a device for detecting a horizontal synchronization signal of an image forming apparatus. The device includes a light intensity converter to convert light intensity of a first beam emitted from a first light source and light intensity of a second beam emitted from a second light source to be different from each other, and outputting the first and second beams; a photo detector to receive the first beam and the second beam output from the light intensity converter, and outputting a first signal having a first level at a time of receiving the first beam and a second level at a time of receiving the second beam; and a horizontal synchronization signal detector to detect a horizontal synchronization signal of the first beam and a horizontal synchronization signal of the second beam by using the first signal.

Abstract: A light scanning unit includes a light source, a beam deflecting unit which reciprocatingly scans a light beam which is emitted from the light source to form an image sector and a first non-image sector and a second non-image sector disposed at opposite sides of the image sector, a sensor which senses the light beam which is deflected and scanned toward the first non-image sector, and a controller which adjusts a horizontal synchronization of the image sector which is formed by the light beam which is scanned in a first direction and a second direction which is the opposite direction to the first direction based on a time period of a signal which is outputted from the sensor.