Multi-beam scanning device and image forming system and method using the same
First Claim
1. A multi-beam scanning device comprising:
- a plurality of light sources which emit multiple beams, the plurality of light sources including a first light source which emits a first beam, and a second light source which emits a second beam;
a plurality of coupling lenses which couple the multiple beams from the light sources, the plurality of coupling lenses including a first coupling lens which couples the first beam, and a second coupling lens which couples the second beam;
a converging lens device which converts the coupled beams from the coupling lenses into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction that is substantially perpendicular to the main scanning direction, the converging beams which correspond to the first and second beams forming a difference angle that is largest among difference angles formed by all of the converging beams;
a rotary deflector having a reflection surface which is rotated about a fixed rotation axis, the reflection surface deflecting the converging beams from the converging lens device while the reflection surface is rotated; and
a scanning lens device which scans an image surface in the main scanning direction at a substantially uniform velocity by focusing each of the deflected beams from the rotary deflector into a beam spot on the image surface, wherein said multi-beam scanning device is configured to satisfy the conditions;
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Accused Products
Abstract
A multi-beam scanning device includes a plurality of light sources which emit multiple beams. A plurality of coupling lenses couple the multiple beams from the light sources. A converging lens device converts the coupled beams into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction, at least two of the converging beams forming a difference angle therebetween. A rotary deflector has a reflection surface rotated about a fixed rotation axis. The reflection surface deflects the converging beams while the reflection surface is rotated. A scanning lens device scans an image surface in the main scanning direction at a substantially uniform velocity by focusing each deflected beam into a beam spot on the image surface. The multi-beam scanning device is configured to satisfy desired conditions to allow the multi-beam scanning device to achieve excellent optical characteristics without using a polarization beam splitter. Further, an image forming system and method which uses such a multi-beam scanning device is provided.
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Citations
17 Claims
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1. A multi-beam scanning device comprising:
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a plurality of light sources which emit multiple beams, the plurality of light sources including a first light source which emits a first beam, and a second light source which emits a second beam;
a plurality of coupling lenses which couple the multiple beams from the light sources, the plurality of coupling lenses including a first coupling lens which couples the first beam, and a second coupling lens which couples the second beam;
a converging lens device which converts the coupled beams from the coupling lenses into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction that is substantially perpendicular to the main scanning direction, the converging beams which correspond to the first and second beams forming a difference angle that is largest among difference angles formed by all of the converging beams;
a rotary deflector having a reflection surface which is rotated about a fixed rotation axis, the reflection surface deflecting the converging beams from the converging lens device while the reflection surface is rotated; and
a scanning lens device which scans an image surface in the main scanning direction at a substantially uniform velocity by focusing each of the deflected beams from the rotary deflector into a beam spot on the image surface, wherein said multi-beam scanning device is configured to satisfy the conditions;
- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A multi-beam scanning device comprising:
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a plurality of light sources which emit multiple beams, the plurality of light sources including a first light source which emits a first beam, and a second light source which emits a second beam;
a plurality of coupling lenses which couple the multiple beams from the light sources, the plurality of coupling lenses including a first coupling lens which couples the first beam, and a second coupling lens which couples the second beam;
a converging lens device which converts the coupled beams from the coupling lenses into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction that is substantially perpendicular to the main scanning direction, the converging lens device including a substantially cylindrical lens, the converging beams which correspond to the first and second beams forming a difference angle that is largest among difference angles formed by all of the converging beams;
a rotary deflector having a reflection surface which is rotated about a fixed rotation axis, the reflection surface deflecting the converging beams from the cylindrical lens while the reflection surface is rotated, the reflection surface spaced at a constant distance from the rotation axis; and
a scanning lens device which scans an image surface in the main scanning direction at a substantially uniform velocity by focusing each of the deflected beams from the rotary deflector into a spot on the image surface, wherein said multi-beam scanning device is configured to satisfy the conditions;
- View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A multi-beam scanning device comprising:
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a plurality of light source means for emitting multiple beams, the plurality of light source means including a first light source which emits a first beam, and a second light source which emits a second beam;
a plurality of coupling lens means for collimating the multiple beams from the light source means, the plurality of coupling lens means including a first coupling lens which couples the first beam, and a second coupling lens which couples the second beam;
converging lens means for converting the coupled beams from the coupling lenses into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction that is substantially perpendicular to the main scanning direction, the converging beams which correspond to the first and second beams forming a difference angle that is largest among difference angles formed by all of the converging beams;
rotary deflector means having a reflection surface which is rotated about a fixed rotation axis, for deflecting the converging beams from the converging lens means while the reflection surface is rotated; and
scanning lens means for scanning an image surface in the main scanning direction at a substantially uniform velocity by focusing each of the deflected beams from the rotary deflector into a beam spot on the image surface, wherein said multi-beam scanning device is configured to satisfy the conditions;
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16. An image forming system comprising:
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a multi-beam scanning device; and
a photoconductive medium having an image surface, wherein the photoconductive medium is electrostatically charged, an electrostatic image is formed on the photoconductive medium when subjected to a multi-beam scanning by the multi-beam scanning device, and the electrostatic image is transformed into a viewable image by a development of the electrostatic image using a toner, said multi-beam scanning device including;
a plurality of light sources which emit multiple beams, the plurality of light sources including a first light source which emits a first beam, and a second light source which emits a second beam;
a plurality of coupling lenses which couple the multiple beams from the light sources, the plurality of coupling lenses including a first coupling lens which couples the first beam, and a second coupling lens which couples the second beam;
a converging lens device which converts the coupled beams from the coupling lenses into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction that is substantially perpendicular to the main scanning direction, the converging beams which correspond to the first and second beams forming a difference angle that is largest among difference angles formed by all of the converging beams;
a rotary deflector having a reflection surface which is rotated about a fixed rotation axis, the reflection surface deflecting the converging beams from the converging lens device while the reflection surface is rotated; and
a scanning lens device which scans the image surface of the photoconductive medium in the main scanning direction at a substantially uniform velocity by focusing each of the deflected beams from the rotary deflector into a spot on the image surface, said multi-beam scanning device being configured to satisfy the conditions;
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17. A method of forming an image on an image surface of a photoconductive medium in an image forming system, the method comprising the steps of:
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providing a multi-beam scanning device including a plurality of light sources which emit multiple beams, the plurality of light sources including a first light source which emits a first beam, and a second light source which emits a second beam, a plurality of coupling lenses which couple the multiple beams from the light sources, the plurality of coupling lenses including a first coupling lens which couples the first beam, and a second coupling lens which couples the second beam, a converging lens device which converts the coupled beams from the coupling lenses into converging beams, the converging beams being elongated in a direction corresponding to a main scanning direction and converging only in a direction corresponding to a sub-scanning direction that is substantially perpendicular to the main scanning direction, the converging beams which correspond to the first and second beams forming a difference angle that is largest among difference angles formed by all of the converging beams, a rotary deflector having a reflection surface which is rotated about a fixed rotation axis, the reflection surface deflecting the converging beams from the converging lens device while the reflection surface is rotated, and a scanning lens device which scans the image surface of the photoconductive medium in the main scanning direction at a substantially uniform velocity by focusing each of the deflected beams from the rotary deflector into a spot on the image surface, said multi-beam scanning device being configured to satisfy the conditions (1) θ
2β
2·
A/L<
0.0005; and
(2) Ø
>
tan−
1[(Ø
1+Ø
2)/2L1], where A is a constant distance between the reflection surface and the rotation axis, θ
is the largest difference angle measured in terms of radians, Ø
1 is an effective diameter of the first coupling lens through which the first beam passes, Ø
2 is an effective diameter of the second coupling lens through which the second beam passes, β
is a transverse magnification of the scanning lens device in the sub-scanning direction, L1 is the smaller one of a first distance between the first coupling lens and the reflection surface and a second distance between the second coupling lens and the reflection surface; and
L is a distance between the reflection surface and the image surface; and
forming an electrostatic image on the image surface of the photoconductive medium by subjecting the photoconductive medium to a multi-beam scanning of said multi-beam scanning device, in order to transform the electrostatic image into a viewable image by a development of the electrostatic image using a toner.
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Specification