Beam-spot position compensation method, optical scanning device, and multi-color image forming device
AssigneeRicoh Company, Ltd.
InventorsShigeaki Imai, Tomohiro Nakajima
Life of this patent
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Abstract
In a beam-spot position compensation method for use in an optical scanning device which scans a surface of a photosensitive medium by a light beam emitted by a light source, a plurality of sections are defined by dividing a scanning region on the scanned surface. An emission timing of the light beam for every section is adjusted so that a spacing between beam-spot positions corresponding to pixels of start and end of each section is changed by a predetermined amount. The sparseness or denseness of beam-spot position spacings of the plurality of sections in the whole scanning region is compensated.
Claims19
An optical scanning device which includes one or more optical deflectors deflecting one or more light beams from one or more light sources, and one or more scanning/focusing optical systems focusing each deflected light beam on each of one or more surfaces of photoconductive mediums as an optical spot thereon, and the optical scanning device performing optical scanning of each of the one or more surfaces of the photoconductive mediums, comprising:
- a scanning line compensation unit compensating an inclination of a scanning line and/or a deflection of a scanning line on the one or more scanned surfaces;
- and
- a position-error compensation unit compensating a position error in a main scanning direction of the optical spots corresponding to adjoining pixels resulting from the compensation of the scanning line compensation unit,
- wherein the scanning line compensation unit is configured to mechanically vary an optical path of the deflected light beam, and a change of a spacing in the main scanning direction of optical spots corresponding to adjoining pixels being produced by the compensation of the scanning line compensation unit, and
- the position-error compensation unit is configured to compensate the change of the spacing in the main scanning direction of the optical spots corresponding to the adjoining pixels by adjustment of a timing of respective startings and endings of application of an image signal applied in the main scanning direction of the optical spots, and
- an amount of the compensation of the spacing change being varied in accordance with a position in the main scanning direction so that respective spacings in the main scanning direction of the optical spots corresponding to the adjoining pixels for two adjoining positions on each of the one or more scanned surfaces are different from each other.
An image forming device which includes a plurality of image supporting mediums corresponding to a plurality of colors, an optical scanning device forming an electrostatic latent image on a uniformly charged surface of each of the image supporting mediums by irradiating a light beam emitted by one of a plurality of light source units and modulated based on a pixel clock pulse, a development unit developing a toner image from each of the electrostatic latent images on the image supporting mediums, and a transferring unit transferring each of the developed images on the image supporting mediums to a printing sheet in an integrated manner to form a color image thereon, the optical scanning device performing optical scanning of each of the one or more surfaces of image supporting mediums and comprising:
- a scanning line compensation unit compensating an inclination of a scanning line and/or a deflection of a scanning line on the one or more scanned surfaces;
- and
- a position-error compensation unit compensating a change of a spacing in a main scanning direction of the optical spots corresponding to adjoining pixels resulting from the compensation of the scanning line compensation unit,
- wherein the scanning line compensation unit is configured to mechanically vary an optical path of the deflected light beam, and a change of a spacing in the main scanning direction of optical spots corresponding to adjoining pixels being produced by the compensation of the scanning line compensation unit, and
- the position-error compensation unit is configured to compensate the change of the spacing in the main scanning direction of the optical spots corresponding to the adjoining pixels by adjustment of a timing of respective startings and endings of application of an image signal applied in the main scanning direction of the optical spots, and
- an amount of the compensation of the spacing change being varied in accordance with a position in the main scanning direction so that respective spacings in the main scanning direction of the optical spots corresponding to the adjoining pixels for two adjoining positions on each of the one or more scanned surfaces are different from each other.
Dependencies are inferred from the claim text.