Patent ID: 6839076

Claim:
A light scanning unit comprising: a first optical system modifying a cross-sectional beam shape of a luminous flux emitted from a light source to a predetermined shape; a light deflecting unit having at least one reflective surface, wherein the luminous flux modified by the first optical system is deflected, in a first direction in a predetermined direction and a length of the deflected luminous flux in the first direction is greater than a length of a single reflective surface thereof along the first direction; a second optical system making the luminous flux deflected in the first direction by the light deflecting unit form an image on an object to be scanned; and a sensor for detection of a write position, setting a timing to modulate an intensity of the luminous flux from the light source with image information, the sensor being positioned at an end of a side on which a cross-sectional beam diameter of the luminous flux is great, of a scanning end of the first direction on the object to be scanned.