Patent attributes
An exposure device has a light emitting unit for emitting a laser beam based on an image signal. The laser beam emitted from the light emitting unit is incident on a polygon mirror through a cylindrical lens. The laser beam reflected on the polygon mirror is illuminated on the surface of a photo sensitive drum through two fθ lenses and a mirror. By doing so, an electrostatic latent image is formed on a drum surface on the basis of an image signal. Further, the exposure device has a housing for holding the light emitting unit, cylindrical lens, polygon mirror, fθ lenses and mirror in a mutually and highly accurate state. A dowel is so provided as to project from the bottom of the housing and functions as a rotation shaft for rotating the exposure device. The dowel is provided on an axis passing through an exposure light spot illuminated in the drum surface by the laser beam.
