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US 6,288,819 B1Granted
Scanning image forming lens and optical scanning apparatus
AssigneeRicoh Company, Ltd.
InventorsMaga Aoki, Kohji Sakai
Life of this patent
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AssigneeRicoh Company, Ltd.
InventorsMaga Aoki, Kohji Sakai
Estimating the term…
A scanning and image forming lens system in an optical scanning apparatus optical scans a surface to be scanned by deflecting a luminous flux emitted from a light source in a direction corresponding to a main scanning direction via an optical deflector at equiangular velocity. The scanning image forming lens system transmits the luminous flux deflected by the optical deflector so as to condense the luminous flux into an optical beam spot on the surface to be scanned and to scan the surface to be scanned with the optical beam spot. The scanning image forming lens system includes one or more image forming optical elements including at least one lens. At least one lens surface of the at least one lens of the scanning image forming lens system has a non-arc shape in a sub scanning cross section. The non-arc shape changes according to a position in a direction that is substantially perpendicular to the sub scanning cross section such that a positional deviation of the optical beam waist of the deflected luminous flux from the surface to be scanned at each position in the direction perpendicular to the sub scanning cross section, which is caused by a paraxial curvature of field of the scanning image forming lens system in a sub scanning direction, is corrected.
An apparatus comprising:
An apparatus according to claim 20, wherein defocusing lines for all of the image heights are substantially coincident with each other.
An apparatus according to claim 20, wherein all of the beam spot diameters are within a range for all of the image heights.
An image forming apparatus for optically scanning a surface to be scanned by deflecting a luminous flux emitted from a light source at equiangular velocity via an optical deflector so as to transmit the deflected luminous flux through the apparatus and to condense the deflected luminous flux into an optical beam spot on the surface to be scanned so as to form images having image heights, the luminous flux condensed by the apparatus into the optical beam spot including an optical beam waist, the apparatus comprising:
A method of forming a lens system for an optical scanning apparatus for optically scanning a surface to be scanned by deflecting a luminous flux emitted from a light source at equiangular velocity via an optical deflector so as to transmit the deflected luminous flux through the lens system and to condense the deflected luminous flux into an optical beam spot on the surface to be scanned so as to form images having image heights, the luminous flux condensed by the lens system into the optical beam spot including an optical beam waist, the method comprising:
An apparatus comprising:
Dependencies are inferred from the claim text.