OPTICAL DEVICE, IMAGE READING DEVICE, AND IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To enable an optical device which is constituted of light-receiving elements and light-emitting elements that are arranged in an array form, to be reduced in number of adjustments and positional displacement due to thermal expansion and shrinkage. SOLUTION: The optical device is equipped with optical element groups 20, which are used for reading or writing and moves physically accompanying a reading plane or a writing plane. In the optical device, where the adjacent optical element group 20 from among the optical element groups 20 is arranged at a prescribed distance in the physically moving direction, a board 22, on which the optical element group 20 is mounted, is linked to the board 22 on which the adjacent optical element group 20 is mounted, by a holding member, 24 whose thermal expansion coefficient is smaller than that of the board 22 for maintaining a prescribed distance Py. At this point, distance Qy, between the bonding positions of the holding member 24 that links the board 22 together, is set longer than the prescribed distance Py. COPYRIGHT: (C)2008,JPO&INPIT