Optical scanning device and image forming apparatus
AssigneeRicoh Company, Ltd.
InventorsYoshinori Hayashi, Taira Kouchiwa
Life of this patent
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Abstract
A light flux emitted from a light source is split into two by a light flux splitting unit, and these are respectively made incident on upper and lower tiers of polygon mirrors of a deflecting unit which coaxially rotates two polygon mirrors one on the other while being shifted in angles from each other. The respective light fluxes that have been deflected for scanning at mutually different timings by the deflecting unit respectively reach individual photodetectors through a first scanning lens, mirrors, and a second scanning lens as a predetermined light system and carry out main scanning.
Claims7
An optical scanning device comprising:
- a plurality of light sources that are modulation-driven, each of which is made a common light source;
- a deflecting unit having a plurality of tiers of multi-facet reflecting mirrors on a common rotation axis;
- a light flux splitting unit that splits beams from the common light source and makes the split beams incident on mutually different tiers of reflecting mirrors of the deflecting unit;
- a plurality of surfaces to be scanned;
- a scanning optical system that guides the beams made to scan from the deflecting unit to the surfaces to be scanned;
- and
- light-receiving units that detect beams made to scan by the deflecting unit, so that the beams split from the common light source scan mutually different surfaces, wherein
- the mutually different tiers of multi-facet reflecting mirrors is shifted from each other in terms of angles in a rotating direction, and the following conditions are satisfied:
- θ/2<2π/M−φ,
- and
- θ/2<φ,
- and
- θ/2<2α
- wherein
- θ:
- Angle of view including beams that reach the light-receiving units
- α:
- Average incidence angle on the reflecting mirror at an effective scanning width
- φ:
- Angle shift in a rotating direction between the different tiers of multi-facet reflecting mirrors
- M:
- Number of faces of the multi-facet reflecting mirror.
An image forming apparatus comprising an optical scanning device, the optical scanning device including;
- a plurality of light sources that are modulation-driven, each of which is made a common light source;
- a deflecting unit having a plurality of tiers of multi-facet reflecting mirrors on a common rotation axis;
- a light flux splitting unit that splits beams from the common light source and makes the split beams incident on mutually different tiers of reflecting mirrors of the deflecting unit;
- a plurality of surfaces to be scanned;
- a scanning optical system that guides the beams made to scan from the deflecting unit to the surfaces to be scanned;
- and
- light-receiving units that detect beams made to scan by the deflecting unit, so that the beams split from the common light source scan mutually different surfaces, wherein
- the mutually different tiers of multi-facet reflecting mirrors is shifted from each other in terms of angles in a rotating direction, and the following conditions are satisfied:
- θ/2<2π/M−φ,
- and
- θ/2<φ,
- and
- θ/2<2α
- wherein
- θ:
- Angle of view including beams that reach the light-receiving units
- α:
- Average incidence angle on the reflecting mirror at an effective scanning width
- φ:
- Angle shift in a rotating direction between the different tiers of multi-facet reflecting mirrors
- M:
- Number of faces of the multi-facet reflecting mirror.
- And wherein
- the image forming apparatus has a plurality of image carriers corresponding to the respective surfaces to be scanned.
Dependencies are inferred from the claim text.