Laser beam optical scanning system
AssigneeMinolta Co., Ltd.
InventorMuneo Kuroda
Life of this patent
Estimating the term…
Abstract
A laser beam optical scanning system which has a laser source unit for emitting a laser beam which is a parallel pencil of rays, a first imaging system for imaging the laser beam emitted from the laser source unit on a reflective facet of a deflector, and a second imaging system for imaging the laser beam deflected by the deflector on a photosensitive drum. At least one of the first and the second imaging systems has a resin lens. The resin lens changes its power according to temperature so as to offset a change in light converging performance of the laser source unit.
Claims25
A laser beam optical scanning system which deflects a laser beam modulated in accordance with image data by using a deflector to scan the laser beam on a scanning surface, the laser beam optical scanning system comprising:
- a laser source unit which converges a laser beam to emit a substantially parallel pencil of rays, the laser source unit changing the convergence of the laser beam in accordance with a change in temperature;
- first imaging means for imaging the laser beam emitted from the laser source unit on a reflective facet of the deflector in a linear form extending in a plane of deflection to be made by the deflector;
- second imaging means for imaging the laser beam deflected by the deflector on the scanning surface;
- and
- a resin lens which is provided in the first and/or the second imaging means, the refracting power of the resin lens changing according to a change in temperature so as to offset the change in the converging performance of the laser unit, wherein the resin lens meets a condition indicated by an expression
- .vertline.f.sub.1 /f.sub.f .vertline.>1.8
- in which, f.sub.1 denotes a focal length of the resin lens in respect to a direction parallel to the plane of deflection;
- and
- f.sub.f denotes a focal length of the second imaging means in respect to a direction parallel to the plane of deflection.
A laser beam optical scanning system which deflects a laser beam modulated in accordance with image data by using a deflector to scan the laser beam on a scanning surface, the laser beam optical scanning system comprising:
- a laser source for radiating a laser beam;
- a holder for holding the laser source, the holder stretching or shrinking with change in temperature, thereby changing location of the laser source;
- a convergent member for changing the laser beam radiated from the laser source into a substantially parallel pencil of rays;
- first imaging means for imaging the laser beam emergent from the convergent member on a reflective facet of the deflector in a linear form extending in a plane of deflection to be made by the deflector;
- second imaging means for imaging the laser beam deflected by the deflector on the scanning surface;
- and
- a resin lens provided in the first and/or the second imaging means, the refractive power of the resin lens changing according to a change in temperature, wherein the resin lens meets a condition indicated by an expression
- .vertline.f.sub.1 /f.sub.f .vertline.>1.8
- in which, f.sub.1 denotes a focal length of the resin lens in respect to a direction parallel to the plane of deflection;
- and
- f.sub.f denotes a focal length of the second imaging means in respect to a direction parallel to the plane of deflection.
A laser beam optical scanning system with deflects a laser beam modulated in accordance with image data by using a deflector to scan the laser beam on a scanning surface, the laser beam optical scanning system comprising:
- a laser source for radiating a laser beam;
- a holder for holding the laser source, the holder stretching or shrinking with a change in temperature, thereby changing location of the laser source;
- a convergent member for changing the laser beam radiated from the laser source into a substantially parallel pencil of rays;
- first imaging means for imaging the laser beam emergent from the convergent member on a reflective facet of the deflector in a linear form extending in a plane of deflection to be made by the deflector;
- second imaging means for imaging the laser beam deflected by the deflector on the scanning surface;
- and
- a resin lens provided in the first and/or the second imaging means, the refractive power of the resin lens changing according to a change in temperature;
- wherein a change in the location of the laser source is offset by a change in the power of the resin lens so that the imaging of the laser beam on the scanning surface is substantially constant despite temperature changes;
- and
- wherein the resin lens meets a condition indicated by an expression
- .vertline.f.sub.1 /f.sub.f .vertline.>1.8
- in which, f.sub.1 denotes a focal length of the resin lens in respect to a direction parallel to the plane of deflection;
- and
- f.sub.f denotes a focal length of the second imaging means in respect to a direction parallel to the plane of deflection.
A laser beam optical scanning system for scanning a laser beam across a scanning surface comprising:
- a laser source for radiating a laser beam;
- a collimator lens having a focal length f.sub.CL for forming the laser beam in substantially a parallel pencil of rays;
- a metal holder for positioning the laser source a predetermined distance from the collimator lens;
- a deflector member;
- a plastic cylindrical lens having a focal length f.sub.CL focusing the parallel pencil of rays on the deflector member, the ratio of f.sub.CY /f.sub.CL being approximately 15;
- and
- an imaging means for receiving the pencil of rays reflected off the deflector member and imaging them on the scanning surface including a plastic lens with a toric surface, any temperature change imposed on the metal holder, plastic cylindrical lens and plastic lens with a toric surface being compensated so that an infocus imaging of the pencil of rays on the scanning surface can be maintained, wherein the toric plastic lens meets a condition indicated by an expression
- .vertline.f.sub.1 /f.sub.f .vertline.>1.8
- in which, f.sub.1 denotes a focal length of the toric plastic lens in respect to a direction parallel to the plane of deflection;
- and
- f.sub.f denotes a focal length of the imaging means in respect to a direction parallel to the plane of deflection.
A laser beam optical scanning system which deflects a laser beam modulated in accordance with image data by using a deflector to scan the laser beam on a scanning surface, the laser beam optical scanning system comprising:
- a laser source unit which converges a laser beam to emit a substantially parallel pencil of rays, said laser source unit changing its converging performance according to temperature;
- first imaging means which includes a cylindrical resin lens for converging the laser beam rays to a focal point in a sub-scanning direction, and which images the laser beam emitted from the laser source unit on a reflective facet of the deflector in a linear form extending in a plane of deflection to be made by the deflector;
- and
- second imaging means which images the laser beam deflected by the deflector on the scanning surface;
- wherein the refractive power of the resin lens changes according to a change in temperature so as to offset a change in the converging performance of the laser source unit and the resin lens meets a condition indicated by
- .vertline.f.sub.1 /f.sub.f .vertline.>1.8
- in which f.sub.1 denotes a focal length of the resin lens in respect to a direction parallel to the plane of deflection, and
- f.sub.f denotes a focal length of the second imaging means in respect to a direction parallel to the plane of deflection.
Dependencies are inferred from the claim text.