OPTICAL SCANNING APPARATUS, IMAGE FORMING APPARATUS, AND SCANNING-LINE-CHANGE CORRECTING METHOD

Abstract

A first plastic lens and a second plastic lens constituting each imaging optical system are arranged on opposite sides of an optical deflector, so that main scanning directions of optical beams scanned by the single optical deflector become substantially parallel to each other, and the first plastic lens and the second plastic lens of at least one of the plurality of (four) imaging optical systems are formed such that secondary components at scanning positions on the (four) surfaces to be scanned are arranged in a same direction, and are molded by a same mold cavity

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an optical scanning apparatus according to a first embodiment of the present invention;

FIG. 2 is a front view of the optical scanning apparatus shown in FIG. 1;

FIG. 3 is a plan view of an optical scanning apparatus according to a second embodiment of the present invention;

FIG. 4 is a front view of the optical scanning apparatus shown in FIG. 3;

FIG. 5 is a front view of an optical scanning apparatus according to a third embodiment of the present invention;

FIG. 6 is a front view of a modified example of the optical scanning apparatus according to the third embodiment;

FIG. 7 is a front view of an optical scanning apparatus according to a fourth embodiment of the present invention;

FIG. 8 is a front view of an optical scanning apparatus according to a fifth embodiment of the present invention;

FIG. 9 is a front view of an optical scanning apparatus according to a sixth embodiment of the present invention;

FIG. 10 is a front view of an optical scanning apparatus according to a seventh embodiment of the present invention;

FIG. 11 is a front view of the optical scanning apparatus shown in FIG. 10;

FIG. 12 is a plan view of an optical scanning apparatus according to an eighth embodiment of the present invention;

FIG. 13A is a graph of a scanning line curvature and out-of-color registration according to a conventional technique, in which optical design is made such that secondary components of four colors (Y, C, M, Bk) are different from each other on a photoconductor;

FIG. 13B is a graph of a scanning line curvature and out-of-color registration according to the embodiments;

FIG. 14 is a graph of a scanning line curvature when optical design is made such that secondary components are different from each other according to the conventional technique;

FIG. 15 is a perspective view of a color image forming apparatus that includes the optical scanning apparatus according to the embodiments;

FIG. 16 is a side view of the color image forming apparatus shown in FIG. 15; and

FIG. 17 is an exploded perspective view of a laser unit in the optical scanning apparatus shown in FIG. 15.

Claims

1. An optical scanning apparatus comprising a plurality of imaging optical systems formed of at least one or more plastic lenses, in which optical beams emitted from a plurality of light source units are imaged on a single deflecting unit, and the optical beams deflected by the deflecting unit are imaged and scanned on a plurality of corresponding surfaces to be scanned via the respective imaging optical systems, wherein the at least one or more plastic lenses constituting each imaging optical system are arranged on opposite sides of the deflecting unit, so that main scanning directions of the optical beams scanned by the deflecting unit become substantially parallel to each other, and the at least one or more plastic lenses in the imaging optical systems are formed such that secondary components at scanning positions on the surfaces to be scanned are arranged in a same direction, and are molded by a same mold cavity.

2. The optical scanning apparatus according to claim 1, wherein each imaging optical system has at least one or more folding mirrors, andnumber of the folding mirrors that fold back the optical beams having passed through the at least one or more plastic lenses is the same for each plastic lens.

3. The optical scanning apparatus according to claim 1, wherein the at least one or more plastic lenses constituting the imaging optical system are laminated in a sub-scanning direction orthogonal to the main scanning direction.

4. The optical scanning apparatus according to claim 1, wherein the at least one or more plastic lenses constituting the imaging optical system are integrally formed in the sub-scanning direction orthogonal to the main scanning direction.

5. The optical scanning apparatus according to claim 1, wherein the optical beams are generated by a multi-semiconductor laser.

6. The optical scanning apparatus according to claim 1, wherein each imaging optical system has at least two plastic lenses, anda combination of the at least two plastic lenses is defined.

7. The optical scanning apparatus according to claim 1, wherein each imaging optical system has at least two plastic lenses, andthe at least two plastic lenses can be identified.

8. The optical scanning apparatus according to claim 1, wherein a part of the plastic lens has a non-transfer surface.

9. An optical scanning apparatus comprising a plurality of imaging optical systems formed of at least two plastic lenses, in which optical beams emitted from a plurality of light source units are imaged on a single deflecting unit, and the optical beams deflected by the deflecting unit are imaged and scanned on a plurality of corresponding surfaces to be scanned via the respective imaging optical systems, wherein a lens arranged closest to the deflecting unit of the at least two plastic lenses constituting the imaging optical system is a common lens corresponding to the surfaces to be scanned, andthe at least one or more plastic lenses in the imaging optical systems are formed such that secondary components at scanning positions on the surfaces to be scanned are arranged in a same direction, and are molded by a same mold cavity.

10. The optical scanning apparatus according to claim 9, wherein each imaging optical system has at least one or more folding mirrors, andnumber of the folding mirrors that fold back the optical beams having passed through the at least one or more plastic lenses is the same for each plastic lens.

11. The optical scanning apparatus according to claim 9, wherein the optical beams are generated by a multi-semiconductor laser.

12. The optical scanning apparatus according to claim 9, wherein each imaging optical system has at least two plastic lenses, anda combination of the at least two plastic lenses is defined.

13. The optical scanning apparatus according to claim 9, wherein each imaging optical system has at least two plastic lenses, andthe at least two plastic lenses can be identified.

14. The optical scanning apparatus according to claim 9, wherein a part of the plastic lens has a non-transfer surface.

15. An optical scanning apparatus comprising a plurality of imaging optical systems formed of at least one or more plastic lenses, in which optical beams emitted from a plurality of light source units are imaged on a plurality of deflecting units, and the optical beams deflected by the respective deflecting units are imaged and scanned on a plurality of corresponding surfaces to be scanned via the respective imaging optical systems, wherein the at least one or more plastic lenses in the imaging optical systems are formed such that secondary components at scanning positions on the surfaces to be scanned are arranged in a same direction, and are molded by a same mold cavity.

16. The optical scanning apparatus according to claim 15, wherein each imaging optical system has at least one or more folding mirrors, andnumber of the folding mirrors that fold back the optical beams having passed through the at least one or more plastic lenses is the same for each plastic lens.

17. The optical scanning apparatus according to claim 15, wherein the at least one or more plastic lenses constituting the imaging optical system are laminated in a sub-scanning direction orthogonal to the main scanning direction.

18. The optical scanning apparatus according to claim 15, wherein the optical beams are generated by a multi-semiconductor laser.

19. The optical scanning apparatus according to claim 15, wherein each imaging optical system has at least two plastic lenses, anda combination of the at least two plastic lenses is defined.

20. The optical scanning apparatus according to claim 15, wherein each imaging optical system has at least two plastic lenses, andthe at least two plastic lenses can be identified.

21. The optical scanning apparatus according to claim 15, wherein a part of the plastic lens has a non-transfer surface.

22. An image forming apparatus that forms an electrostatic latent image on a plurality of image carriers by an optical scanning apparatus, develops the electrostatic latent image with a color toner different for each image carrier, and sequentially superposes and transfers the toner images formed on respective image carriers onto an intermediate transfer body, and thereafter, batch-transfers the toner images on a sheet-like recording medium, thereby obtaining a color image, wherein the optical scanning apparatus is the optical scanning apparatus according to claim 1.

23. An image forming apparatus that forms an electrostatic latent image on a plurality of image carriers by an optical scanning apparatus, develops the electrostatic latent image with a color toner different for each image carrier, and sequentially superposes and transfers the toner images formed on respective image carriers onto an intermediate transfer body, and thereafter, batch-transfers the toner images on a sheet-like recording medium, thereby obtaining a color image, wherein the optical scanning apparatus is the optical scanning apparatus according to claim 9.

24. An image forming apparatus that forms an electrostatic latent image on a plurality of image carriers by an optical scanning apparatus, develops the electrostatic latent image with a color toner different for each image carrier, and sequentially superposes and transfers the toner images formed on respective image carriers onto an intermediate transfer body, and thereafter, batch-transfers the toner images on a sheet-like recording medium, thereby obtaining a color image, wherein the optical scanning apparatus is the optical scanning apparatus according to claim 15.