Scanning optical apparatus and image forming apparatus using the same
AssigneeCanon Kabushiki Kaisha
InventorKazumi Kimura
Life of this patent
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Abstract
A scanning optical apparatus includes incident optical system for causing at least one light beam emitted from a light source to be incident on a deflection device and image formation optical system including at least one refractive optical element and at least one diffraction optical element for imaging said at least one light beam reflected and deflected by the deflection device on a surface to be scanned. The diffraction optical element has at least one of an incident surface having a convex shape in a sub-scanning cross-section facing the deflection device and an exit surface having a convex shape in the sub-scanning cross-section facing the surface to be scanned.
Claims8
A scanning optical apparatus comprising:
- incident optical means for causing at least one light beam emitted from light source means to be incident on deflection means;
- and
- image formation means consisting of one refractive optical element and one diffraction optical element for imaging the at least one light beam reflected and deflected by the deflection means on a surface to be scanned,
- wherein a front focus position of the diffraction optical element in the sub-scanning cross-section is provided between a power arrangement in the sub-scanning cross-section of an on-axis of the refractive optical element and a power arrangement in the sub-scanning cross-section of an off-axis of the refractive optical element, in an optical axis direction;
- wherein the diffraction optical element is provided between the refractive optical element and the surface to be scanned, in the optical axis direction;
- and
- wherein even if a position of said refractive optical element is shifted by 0.1 mm vertically from the optical axis in a sub-scanning cross-section, an on-axis principal ray and an off-axis principal ray of the at least one light beam reach the surface to be scanned at heights whose difference in the sub-scanning direction is less than ±10 μm.
Dependencies are inferred from the claim text.