Optical scanning apparatus and system

• US 5,255,112 A
• Filed: 12/19/1991
• Issued: 10/19/1993
• Est. Priority Date: 12/20/1990
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Maruo, Seiji, Suzuki, Yasuaki, Hori, Yasuro
• Primary Examiner(s): Ben, Loha
• Application Number:
  US07/810,339
• Time in Patent Office: 670 Days
• Field of Search: 359/282, 359/851, 359/727, 359/208, 359/212, 359/196, 359/197, 359/216, 359/217, 359/218, 359/219, 250/235, 250/236, 356/300, 385/146, 346/108, 346/160
• US Class Current: 359/196.1
• CPC Class Codes: G02B 26/125 Details of the optical system between the polygonal mirror and the image plane G02B26/123, G02B26/127 take precedence; F-Theta lenses G02B13/0005

Abstract

A small and inexpensive optical scanning apparatus is attained by an optical block 1 disposed between a rotating mirror 2 and a photosensitive body 3 and having specular surfaces formed at part of inner side of surface so that light from the rotating mirror 2 is reflected within the optical block 1 plural times back and forth and reaches the photosensitive body 3 in order to correct the curvature of field, the distortion aberration and the inclination of surface in an optical scanning system. The length of the optical path within the optical block including reflection is set to 60% or more of the whole length of optical path from the rotating mirror 2 to the photosensitive body 3. The surface of the optical block 1 on the side of the photosensitive body is formed into a curved surface to constitute a concave mirror. The rotating mirror and the photosensitive body are arranged in optically conjugate relation in sub-scanning direction by the focal distance.

Claims

1. An optical scanning apparatus including:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned;

wherein

when the whole effective length of optical path from said scanning means to said object to be scanned is L and the length of optical path within said optical block including reflection is A, A/L>

0.6 is satisfied.

2. An optical scanning apparatus including:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned;

wherein

when a distance from said scanning means to said object to be scanned is T and the length of one side of said optical block in a reflection direction is W, W/T is set to a predetermined value in accordance with the number of times of reflection within said optical block.

3. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned;

wherein a main surface of said optical block does not include a curvature in the main scanning direction and includes a curvature in a sub-scanning direction and said scanning means and said surface to be scanned have an optically conjugate arrangement relation in the sub-scanning direction to each other by a focal distance of a lens constituting said main surface.

4. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned; and

further comprising a cylindrical lens disposed between said optical block and said object to be scanned and having a curvature provided in sub-scanning direction.

5. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned;

wherein said optical block includes a curved surface formed on the side of said object to be scanned and having a curvature provided in a sub-scanning direction and a plane surface formed on the side of said scanning means.

6. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned;

wherein said optical block includes a curved surface formed adjacent to a parallel plane thereof.

7. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned; and

further comprising a lens affixed on part of a parallel plane of said optical block and having one surface formed into a plane surface.

8. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned;

wherein an exit of light going out from said optical block and said object to be scanned are disposed on the side of said scanning means.

9. An electrophotographic printer comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned and forming an electrostatic latent image thereon;

a developing device for developing said electrostatic latent image with toner as a toner image;

a transferring device for transferring said developed toner image onto a recording paper; and

a fixing device for fixing said transferred toner image onto said recording paper.

10. An optical scanning apparatus including:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

wherein

when the whole effective length of optical path from said scanning means to said object to be scanned is L and the length of optical path within said optical block including reflection is A, A/L>

0.4 is satisfied.

11. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

wherein a surface shape of said optical lens on the side of said optical block is convex in the main scanning direction and a surface shape of said optical lens on the side of said scanning means is concave.

12. An optical scanning apparatus according to claim 11, wherein when a radius of curvature of said convex surface is R1 and a radius of curvature of said concave surface is R2, R1/R2<

0.4.

13. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

wherein a main surface of said optical block does not include a curvature in the main scanning direction and includes a curvature in a sub-scanning direction and said scanning means and said surface to be scanned have an optically conjugate relation in the sub-scanning direction to each other by a focal distance of a lens constituting said main surface and a focal direction of said optical lens.

14. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned; and

further comprising a cylindrical lens disposed between said optical block and said object to be scanned and having a curvature provided in sub-scanning direction.

15. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

wherein said optical block includes a curvature provided in sub-scanning direction on a surface on the side of said object to be scanned and a plane surface formed on a surface on the side of said scanning means.

16. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

wherein opposite surfaces of said pair of specular surfaces are formed into parallel planes, and said optical block includes a curved surface formed adjacent to a parallel plane thereof.

17. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

wherein opposite surfaces of said pair of specular surfaces are formed into parallel planes, and further comprising a lens affixed on part of a parallel plane of said optical block and having one surface formed into a plane surface.

18. A facsimile apparatus comprising:

a reading portion including scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned;

encoding means for encoding an image signal read by said reading portion; and

transmitting means for sending the image signal encoded by said encoding means to a communication line.

19. A facsimile apparatus according to claim 18, further comprising:

receiving means for receiving the encoded image signal from said communication line;

decoding means for decoding the image signal received by said receiving means; and

a recording portion including another optical scanning apparatus for recording the image signal decoded by said decoding means.

20. An optical scanning apparatus according to claim 19, wherein said another optical scanning apparatus comprises:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned.

21. An optical scanning apparatus comprising:

a reading sensor;

an optical lens; and

an optical block including a plurality of plane surfaces or curved surfaces and a pair of specular surfaces formed at part of the surfaces for reflecting light toward the inside of said optical block;

said optical block, said optical lens and said reading sensor are disposed in order of description from an object to be read, light from said object to be read being reflected within said optical block back and forth plural times, the light then passing through said optical lens, reaching said reading sensor;

wherein when the whole length of optical path from said object to be read to said reading sensor is L and the length of optical path within said optical block including reflection is A, A/L>

0.4 is satisfied.

22. An optical scanning apparatus according to claim 21, wherein a surface shape of said optical lens on the side of said optical block is convex in main scanning direction and a surface shape of said optical lens on the side of said reading sensor is concave in main scanning direction.

23. An optical scanning apparatus according to claim 21, wherein when a radius of curvature of said convex surface is R1 and a radius of curvature of said concave surface is R2, R1/R2<

0.4.

24. An optical scanning apparatus according to claim 21, wherein opposite surfaces of said pair of specular surfaces are formed into parallel planes.

25. An optical scanning apparatus according to claim 24, further comprising a cylindrical lens disposed between said optical block and said object to be read and having a curvature provided in sub-scanning direction.

26. An optical scanning apparatus according to claim 24, wherein said optical block includes a curved surface formed adjacent to a parallel plane thereof.

27. An optical scanning apparatus according to claim 24, comprising a lens affixed on part of a parallel plane of said optical block and having one surface formed into a plane surface.

28. An optical scanning apparatus according to claim 24, further comprising a cylindrical mirror disposed between said optical block and said object to be read and having a curvature provided in sub-scanning direction.

29. An optical scanning apparatus according to claim 21, wherein a surface of said optical block does not include a curvature in main scanning direction and includes a curvature in sub-scanning direction and said object to be read and said reading sensor have an optically conjugate relation in the sub-scanning direction to each other by a focal distance of a lens constituting said main surface and a focal distance of said optical lens.

30. An optical scanning apparatus according to claim 21, wherein said optical block is made of plastic.

31. An optical scanning apparatus according to claim 21, wherein said optical block includes a curvature provided in sub-scanning direction on a surface on the side of said object to be read and a plane surface formed on a surface on the side of said reading sensor.

32. A reading scanner comprising said optical scanning apparatus according to claim 21.

33. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said optical block being disposed between said scanning means and an object to be scanned, the optical beam from said scanning means being reflected back and forth within said optical block, the reflected optical beam then reaching said object to be scanned; and

further comprising a cylindrical mirror disposed between said optical block and said object to be scanned and having a curvature provided in sub-scanning direction.

34. An optical scanning apparatus comprising:

scanning means for scanning an optical beam in a main scanning direction; and

an optical block including a plurality of plane surfaces or curved surfaces and on which the optical beam scanned by said scanning means is incident, said optical block including a pair of specular surfaces formed in part of said surfaces for reflecting the incident optical beam toward the inside of said optical block;

said scanning means, an optical lens, said optical block and said object to be scanned are disposed in order of description, light from said scanning means passing through said optical lens, the light being reflected back and forth within said optical block, reaching said object to be scanned; and

further comprising a cylindrical mirror disposed between said optical block and said object to be scanned and having a curvature provided in sub-scanning direction.