Optical scanning apparatus and image-forming apparatus using the same
AssigneeCanon Kabushiki Kaisha
InventorManabu Kato
Life of this patent
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Abstract
An optical scanning apparatus includes a light source and a structure for performing light-power control for the light source, the structure including a light-power-detection optical unit that establishes an optically conjugate relationship between a deflecting surface of a deflecting unit and a light-receiving surface of a light-power detector in a main-scanning plane. Accordingly, the storage time of a light beam on the light-power-detection optical unit is increased and variation in the power of light emitted by the light source due to heat generated by the light source and environmental variation is accurately detected.
Claims14
An optical scanning apparatus comprising:
- a light source that emits a light beam;
- a deflecting unit having a deflecting surface that deflects and scans the light beam emitted from the light source;
- a light-power detector that detects the intensity of the light beam deflected and scanned by the deflecting surface of the deflecting unit;
- an imaging optical unit that focuses the light beam deflected and scanned by the deflecting surface of the deflecting unit on a surface to be scanned;
- a light-power-detection optical unit for guiding the light beam deflected and scanned by the deflecting surface of the deflecting unit toward the light-power detector;
- and
- an automatic power controller that controls the intensity of the light beam emitted from the light source on the basis of a signal obtained from the light-power detector,
- wherein the light-power-detection optical unit establishes an optically conjugate relationship between the deflecting surface of the deflecting unit and a light-receiving surface of the light-power detector in the main-scanning plane, and
- a scanning angular velocity Vapc on the light-receiving surface of the light-power detector satisfies the following expression:
- Vapc<f/10
- where f is fθ coefficient of the optical scanning apparatus in the unit of mm/rad.
The optical scanning apparatus comprising:
- a light source that emits a light beam;
- a deflecting unit having a deflecting surface that deflects and scans the light beam emitted from the light source;
- a light-power detector that detects the intensity of the light beam deflected and scanned by the deflecting surface of the deflecting unit;
- an imaging optical unit that focuses the light beam deflected and scanned by the deflecting surface of the deflecting unit on a surf ace to be scanned;
- a light-power-detection optical unit for guiding the light beam deflected and scanned by the deflecting surface of the deflecting unit toward the light-power detector;
- and
- an automatic power controller that controls the intensity of the light beam emitted from the light source on the basis of a signal obtained from the light-power detector,
- wherein the light-power-detection optical unit establishes an optically conjugate relationship between the deflecting surface of the deflecting unit and a light-receiving surface of the light-power detector in the main-scanning plane,
- wherein the light source has a plurality of light-emitting portions, and
- wherein the intensity control for the light source is successively performed for the light-emitting portions one at a time in each scanning cycle, so that the intensity control for all of the light-emitting portions is completed after a plurality of scanning cycles.
Dependencies are inferred from the claim text.