Patent ID: 7253830
Filing Date: 2007-08-07
Classification: B41J

Abstract:
1. A laser beam printer comprising: a rotary apparatus having: a sleeve; a rotation shaft which is inserted into the sleeve; a polygon mirror which is fixed to the rotation shaft; a yoke which is fixed to the rotation shaft; permanent magnets which are fixed to the yoke; and a stator which is fixed to the sleeve, and which is opposed to the permanent magnets; a laser oscillating apparatus; and a photosensitive drum, wherein: tapped portion is formed in a part of an outer circumference of the rotation shaft, and a part of an inner circumference of the sleeve, respectively; the tapped portions are temporarily engaged with each other in a process of inserting the rotation shaft into the sleeve by a rotating of the rotation shaft to a predetermined direction, and then the tapped portions are separated from each other by continuing the rotating; the rotation shaft that is inserted into the sleeve is retained by the separated condition; and a rotation direction of the rotation shaft in a driving process is identical with the predetermined direction.