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US 2011/0216152 A1Published application
Scanning optical apparatus
AssigneeCanon Kabushiki Kaisha
InventorManabu Kato
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AssigneeCanon Kabushiki Kaisha
InventorManabu Kato
Estimating the term…
A scanning optical apparatus includes a light source, a deflecting element for deflecting a beam of light emitted from the light source, an optical device for causing the beam of light emitted from the light source to be imaged into a linear shape long in the main scanning direction on the deflecting surface of the deflecting element. The optical device is comprised of a first optical element and a second optical element, and a third optical element for causing the beam of light deflected by the deflecting element to be imaged into a spot-like shape on a surface to be scanned. The third optical element includes a single lens, the opposite lens surfaces of which both include a toric surface of an aspherical surface shape in the main scanning plane, the curvatures of the opposite lens surfaces in the sub scanning plane being continuously varied from the on-axis toward the off-axis in the effective portion of the lens.
1-36. (canceled)
In an optical scanner having a source of a light beam, a rotatable polygonal mirror for deflecting the light beam and an imaging lens system for focusing the light beam deflected by said polygonal minor to form a beam spot on a surface to be scanned, wherein the light beam is incident on the polygonal mirror in a direction inclined relative to an optical axis of said imaging lens system in the main scanning plane, the improvement wherein said imaging lens system comprises a plurality of surfaces having curvatures in a sub-scanning direction which vary continuously along a main scanning direction over an effective area of said imaging lens system and independently of curvatures in the main scanning direction, and wherein the curvatures in the sub-scanning direction are non-symmetrical along a main scanning direction with respect to a sub-scanning plane including the optical axis, and wherein the curvatures in the main and sub-scanning directions are rotationally non-symmetrical with respect to an optical axis of said imaging lens system.
In an optical scanner having a source of a light beam, a rotatable polygonal mirror for deflecting the light beam and an imaging lens system for focusing the light beam deflected by said polygonal minor to form a beam spot on a surface to be scanned, wherein the light beam is incident on the polygonal mirror in a direction inclined relative to an optical axis of said imaging lens system in the main scanning plane, the improvement wherein said imaging lens system comprises a plurality of surfaces having curvatures in a sub-scanning direction which vary continuously along a main scanning direction over an effective area of said imaging lens system and independently of curvatures in the main scanning direction to provide a substantially constant optical magnification in the sub-scanning direction over the effective scanning region, and wherein the curvatures in the sub-scanning direction are non-symmetrical along a main scanning direction with respect to a sub-scanning plane including the optical axis, and wherein the curvatures in the main and sub-scanning directions are rotationally non-symmetrical with respect to an optical axis of said imaging lens system.
Dependencies are inferred from the claim text.