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US 7,889,426 B2Granted
Diffractive lens and scanning lens formed with diffractive lens
AssigneeHoya Corporation
InventorsShuichi Takeuchi, Yutaka Takakubo
Life of this patent
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AssigneeHoya Corporation
InventorsShuichi Takeuchi, Yutaka Takakubo
Estimating the term…
A scanning lens for an imaging optical system converges a beam emitted by a light source and deflected by a deflector on a target surface to form a beam spot scanning in a main scanning direction thereon. The scanning lens includes a plastic lens formed by injection molding, which has a diffractive lens structure on at least one surface thereof. The diffractive lens structure has a plurality of annular zones arranged concentrically about a rotational axis. Each annular zone has a diffracting surface that diffracts the light beam passing therethrough. The diffractive lens structure has stepped surfaces each connecting adjoining diffracting surfaces. In a plane including the rotational axis and parallel with the main scanning direction, the stepped surfaces are inclined with respect to the rotational axis so that stress working between a metallic molding for the plastic lens and each of the stepped surfaces in demolding is reduced.
A scanning lens for an imaging optical system that converges a beam emitted by a light source and deflected by a deflector on a target surface to form a beam spot scanning in a main scanning direction thereon, the scanning lens including a plastic lens formed by injection molding, the plastic lens having a diffractive lens structure formed by the injection molding on at least one surface thereof, the diffractive lens structure having a plurality of concentric annular zones which are arranged concentrically about a rotational axis, each of the plurality of annular zones having a diffracting surface that diffracts the light beam passing therethrough, the diffractive lens structure having stepped surfaces connecting each adjoining diffracting surfaces, the stepped surfaces being designed such that, in a plane including the rotational axis and parallel with the main scanning direction, the stepped surfaces are inclined with respect to the rotational axis so that stress working between a metallic molding for the plastic lens and each of the stepped surfaces in demolding is reduced.
A diffractive lens made of plastic formed by injection molding, the diffractive lens having a diffractive lens structure formed by the injection molding on at least one surface thereof, the diffractive lens structure having a plurality of concentric annular zones which are arranged concentrically about a rotational axis, each of the plurality of annular zones having a diffracting surface that diffracts the light beam pass therethrough, the diffractive lens structure having stepped surfaces connecting each adjoining diffracting surfaces, the stepped surfaces being designed such that, in a plane including the rotational axis, the stepped surfaces are inclined with respect to the rotational axis so that stress working between a metallic molding for the plastic lens and each of the stepped surfaces in demolding is reduced.
Dependencies are inferred from the claim text.