US Patent 7118233 Polygon mirror drive motor

A polygon mirror drive motor according to the present invention comprises a stator and a rotor having a hexahedron-shaped polygon mirror and a rotation drive shaft. The polygon mirror in one preferred mode is comprised of two square faces that are parallel with each other and orthogonal to said rotation drive shaft, the two square faces having each a center hole in which said rotation drive shaft is inserted, and four mirror facets that are parallel with said rotation drive shaft. In the polygon mirror, a value of D/L is preferably in a range of from 0.37 to 0.41 where D is a diameter of said center hole and L is an edge length of said two square faces.