| 摘要 |
PROBLEM TO BE SOLVED: To provide a light beam scanner in which the deviation of a focusing position of a light beam in an optical path direction due to the thermal expansion of a constant speed deflection means is reduced. SOLUTION: An exposure unit E is provided with semiconductor lasers 1A to 1D, collimator lenses 2A to 2D, spacers 40A to 40D, a polygon mirror 6, a first fθlens 7, a second fθlens 8 and a case 60 or the like. The respective spacers 40A to 40D support the semiconductor lasers 1A to 1D, the collimator lenses 2A to 2D with predetermined gaps in an optical path direction of laser beams L1 to L4. The spacers 40A to 40D are made of aluminum and have thermal expansion characteristic with which the gap between the semiconductor lasers 1A to 1D and the collimator lenses 2A to 2D are reduced so that the deviation of the focusing points of the laser beams L1 to L4 which are to be focused on the surface of photoreceptor drums 101A to 101D in the optical path direction due to the thermal expansion of the first fθlens 7 and the second fθlens 8 in a thermal change is reduced. COPYRIGHT: (C)2007,JPO&INPIT |
