JP2007171626A - Optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and simply adjustable optical scanner in which the diameter of beam spot is made small and positional shift of the beam spot is reduced. <P>SOLUTION: A cylindrical lens 5 being an anamorphic optical element which focuses a luminous flux from a coupling optical system at least in a subscanning direction is mounted on a housing 33 via an intermediate member 32 in the optical scanner. The cylindrical lens 5 is fixed at its one end of the longitudinal direction on the intermediate member 32 in a cantilever form, the position of the lens is adjustable in the subscanning direction (direction shown by arrow D1) and the eccentricity of the lens is adjustable around the axis (direction shown by arrow D2) which is parallel to an optical axis before the lens is fixed to the intermediate member 32. The position of the intermediate member 32 is adjustable in the optical axis direction and in a main scanning direction (direction shown by arrow D3) and the eccentricity of the intermediate member 32 is adjustable around the axis (direction shown by arrow D4) which is parallel to the subscanning direction before the intermediate member is fixed on the housing 33. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical scanning apparatus that performs optical scanning, and an image forming apparatus such as a copying machine, a printer, a facsimile, and a plotter having the optical scanning apparatus.

In electrophotographic image forming apparatuses used in laser printers, digital copying machines, plain paper fax machines, etc., colorization and speeding-up have progressed, and tandem image forming apparatuses having a plurality of (usually four) photoreceptors have become widespread. Yes.
As a color electrophotographic image forming apparatus, there is a system in which only one photoconductor is provided and the photoconductor is rotated by the number of colors, but the productivity is inferior. That is, in the case of four colors and one drum type, the photosensitive member needs to rotate four times.
However, in the case of the tandem method, the number of light sources inevitably increases, and accordingly, the number of parts increases, color shift due to wavelength difference between a plurality of light sources, and cost increase. Further, deterioration of the semiconductor laser is cited as a cause of the failure of the writing unit. As the number of light sources increases, the probability of failure increases and the lifetime decreases.

Therefore, an optical scanning device using a light beam splitting element that enables high-speed image output while reducing the number of light sources has been proposed. This optical scanning device has the advantages that the number of parts can be reduced and the cost can be reduced, the failure rate of the entire unit is reduced, and the life can be extended.
With the increase in image quality and density of laser printers, there are increasing demands for beam spot diameter reduction, beam spot position shift reduction, and cost reduction in optical scanning devices.
For this purpose, each optical component is processed with high accuracy and placed in the housing with high accuracy, but the cost of each optical component increases. Moreover, there is a limit to the optical characteristics that can be obtained no matter how highly accurate the optical parts are processed.
Japanese Patent Application Laid-Open No. 2004-228561 proposes increasing the placement accuracy by adjusting the position of the optical component. Specifically, the optical element provided in front of the deflector is held by the second holder, the second holder is attached to the first holder, and the first holder The two holders can be adjusted in the optical axis direction, and the optical element can be adjusted in the optical axis direction with respect to the second holder.

JP 2002-365570 A

  However, the method described in Patent Document 1 has a problem that only the adjustment of the beam waist position can be handled because it can only deal with the adjustment in the optical axis direction.

  The present invention provides an optical scanning device that can be adjusted at low cost and can be simply adjusted, and that can reduce the beam spot diameter and reduce the beam spot position deviation, and an image forming apparatus that has the optical scanning device and can cope with high image quality. The purpose is to provide.

  In order to achieve the above object, according to the first aspect of the present invention, a light source, a coupling optical system for coupling a beam from the light source, and a light beam from the coupling optical system are condensed at least in the sub-scanning direction. An anamorphic optical element and a plurality of multi-surface reflecting mirrors, and the multi-surface reflecting mirrors of different steps are deviated from each other in the rotational direction, and the deflecting means having a common rotation axis and the common light source A beam splitting unit that splits the beam of the beam into the different-stage reflecting mirror, a scanning optical system that guides the beam scanned by the deflecting unit to a surface to be scanned, the light source, and the deflecting unit An optical scanning device in which beams divided from the common light source scan different surfaces to be scanned. Both one but is mounted via an intermediate member to said housing, and characterized in that is adjustable.

According to a second aspect of the present invention, in the optical scanning device according to the first aspect, the intermediate member is adjustable with respect to the housing, and the anamorphic optical element is adjusted with respect to the intermediate member. And at least one of the adjustable directions of the intermediate member relative to the housing is different from at least one of the adjustable directions of the anamorphic optical element relative to the intermediate member. It is characterized by that.
According to a third aspect of the present invention, in the optical scanning device according to the first or second aspect, the following condition is satisfied.
(1) The outer shape of the anamorphic optical element is longer in the main scanning direction than in the sub-scanning direction.
(2) The receiving surface of the housing on which the intermediate member is mounted is substantially perpendicular to the main scanning direction.
(3) The anamorphic optical element is attached to an intermediate member around the main scanning direction.

According to a fourth aspect of the present invention, in the optical scanning device according to the third aspect, the intermediate member is mounted at substantially the center of the anamorphic optical element in the sub-scanning direction.
According to a fifth aspect of the present invention, in the optical scanning device according to the first or second aspect, there are a plurality of the intermediate members, and the intermediate members are arranged on opposite sides of the light beam passing through the anamorphic optical element. It is characterized by that.
According to a sixth aspect of the present invention, in the optical scanning device according to the fifth aspect, the intermediate member has a longer outer dimension in the main scanning direction and the sub-scanning direction of the anamorphic optical element. It is characterized by being arranged in.

According to a seventh aspect of the present invention, in the optical scanning device according to any one of the first to sixth aspects, the intermediate member has two flat portions orthogonal to each other.
According to an eighth aspect of the present invention, in the optical scanning device according to any one of the first to seventh aspects, the intermediate member is fixed to the housing via an adhesive, and the anamorphic optical element is bonded. It is fixed to the intermediate member via an agent.
According to a ninth aspect of the present invention, in the optical scanning device according to the eighth aspect, the intermediate member is fixed to the housing via an adhesive, and the intermediate member is transparent, The adhesive is an ultraviolet curable resin.

  In the invention of claim 10, a light source, a coupling optical system for coupling a beam from the light source, an anamorphic optical element for condensing a light beam from the coupling optical system at least in the sub-scanning direction, and a plurality The multi-surface reflecting mirrors of the different stages are different from each other in the angle of the rotation direction of the multi-surface reflecting mirrors of different stages, and the deflecting means having a common rotation axis and the beam from the common light source are divided, A beam splitting unit that makes the beams split into the reflecting mirrors of different stages incident; a scanning optical system that guides the beam scanned by the deflection unit to a surface to be scanned; and a housing that holds the light source and the deflection unit. And an optical scanning device in which beams split from the common light source scan different scanning surfaces. At least one of the anamorphic optical elements is flat on an optical axis. Around the a axis, and wherein the rotatable adjustment.

According to an eleventh aspect of the present invention, in the optical scanning device according to any one of the first to tenth aspects, a plurality of beams scan the same scanned surface.
According to a twelfth aspect of the present invention, in the image forming apparatus, the optical scanning device according to any one of the first to eleventh aspects is used.

According to the first, second, or eleventh aspect of the invention, the beam spot diameter can be reduced and the beam spot position deviation can be reduced. Moreover, the component tolerance of the optical element can be relaxed, and the cost can be reduced. In addition, optical components can be shared, and recycling is easy (environmentally friendly).
According to the third or fourth aspect of the present invention, it is difficult to be affected by temperature fluctuations, and it becomes easy to ensure optical characteristics.
According to the invention described in claim 5 or 6, the change in the posture of the optical element is reduced, and good optical characteristics can be obtained.
According to the seventh aspect of the invention, it is possible to adjust the movement in two directions, and it becomes easy to ensure optical characteristics.
According to the invention described in claim 8 or 9, adjustment with a simple and low-cost configuration is facilitated.
According to the invention described in claim 10, the beam waist diameter can be reduced and the beam spot can be reduced in diameter.
According to the twelfth aspect of the present invention, it is possible to provide an image forming apparatus capable of high image quality.

A first embodiment of the present invention will be described below with reference to FIGS.
First, based on FIG. 1, the outline | summary of a structure and function of the optical scanning device 20 in this embodiment is demonstrated. In FIG. 1, reference numerals 1 and 1 ′ denote a semiconductor laser as a light source, 2 denotes a support base (LD base) of the semiconductor laser, 3, 3 ′ denotes a coupling lens, and 4 denotes a half mirror prism as light beam splitting means. 5a and 5b are cylindrical lenses as anamorphic optical elements, 6 is a soundproof glass, 7 is a deflection means comprising an upper polygon mirror 7a as a multi-faced reflecting mirror and a lower polygon mirror 7b as a multi-faced reflecting mirror. 8a and 8b are scanning lens 1 of the scanning optical system, 9 is a mirror of the scanning optical system, 10a and 10b are scanning lens 2 of the scanning optical system, 12K and 12C are photosensitive members as scanning surfaces, 25 Indicates an aperture stop.
The semiconductor lasers 1 and 1 ′, the support base 2 and the coupling lenses 3 and 3 ′ are assembled together to form one light source unit.

The divergent light beam emitted from the semiconductor lasers 1 and 1 ′ is converted into a convergent light beam, a parallel light beam, or a divergent light beam by the coupling lenses 3 and 3 ′. The beams exiting the coupling lenses 3 and 3 ′ pass through an aperture stop 25 for stabilizing the beam diameter on the scanned surface and enter the half mirror prism 4. The beam from the common light source incident on the half mirror prism 4 is divided into upper and lower stages as shown in FIG. 2, and the beams emitted from the half mirror prism 4 become two beams.
Reference numeral 4a denotes a half mirror, which separates transmitted light and reflected light at a ratio of 1: 1. Reference numeral 4b denotes a total reflection surface and has a function of changing the direction. Although a half mirror prism is used here, a similar system may be configured using a single half mirror and a normal mirror. Further, the separation ratio of the half mirror does not need to be 1: 1, and may be set according to the conditions of other optical systems.

The beam emitted from the half mirror prism 4 is converted into a line image that is long in the main scanning direction in the vicinity of the deflecting reflection surface by the cylindrical lenses 5a and 5b provided in the upper and lower stages.
In the deflecting means 7, polygon mirrors 7a and 7b are arranged in the upper and lower stages, respectively, and the rotation direction angle is shifted by (φ). Here, the four polygon mirrors are shifted by φ = 45 deg. The upper and lower polygon mirrors may be formed integrally or may be assembled separately.
As shown in FIG. 3A, when the upper beam B1 from the common light source is scanning the photosensitive member surface (scanned surface), the lower beam B2 is prevented from reaching the scanned surface. Desirably, light is shielded by the light shielding member 13.
Further, as shown in FIG. 3B, when the lower beam B2 from the common light source is scanning a photosensitive surface (scanned surface) different from the upper one, the upper beam B1 reaches the scanned surface. Do not.

Further, when the modulation drive is shifted in the upper and lower stages and the photoconductor corresponding to the upper stage is scanned, the light source is modulated and driven based on the image information of the color (for example, black) corresponding to the upper stage. When scanning the photoconductor corresponding to, the light source is modulated based on the image information of the color (for example, magenta) corresponding to the lower stage.
FIG. 4 is a time chart in the case where black and magenta exposure is performed with a common light source, and all lighting is performed in the effective scanning region. A solid line indicates a portion corresponding to black, and a dotted line indicates a portion corresponding to magenta. In black and magenta, the writing timing is determined by detecting the scanning beam with the synchronous light receiving means arranged outside the effective scanning width. Although the synchronous light receiving means is not shown, a photodiode is usually used.
In FIG. 4, the light amounts in the black and magenta regions are set to be the same. However, since the transmittance and reflectance of the optical element are actually relatively different, if the light amount of the light source is the same, the photoconductor The amount of light reaching the beam will be different. Therefore, as shown in FIG. 5, when the different photoconductor surfaces are scanned, the light amounts set on the different photoconductor surfaces can be made equal by making the set light amounts different from each other.

In this embodiment, two beams are used to scan one photoconductor, but one beam may be used to scan one photoconductor. Although only the configuration corresponding to the two photoconductors is disclosed in FIG. 1, four photoconductors are scanned by disposing an optical system similar to the illustrated optical system with the polygon mirror 7 interposed therebetween. be able to.
For colorization, there are usually four photoreceptors and four or more light sources. Since two beams can be obtained with one light source by the beam splitting method, the number of light sources can be reduced in an opposed scanning multi-beam scanning optical system having four light sources as shown in FIG. In FIG. 6, reference numerals 1a1, 1a2, 1b1, and 1b2 denote light sources.

The plurality of beams emitted from the plurality of light sources 1 and 1 ′ shown in FIG. 1 form two scanning lines on two different photoconductors, respectively, by one scan. At this time, it is necessary to adjust the pitch of the scanning lines in the sub-scanning direction according to the pixel density. As a method often used as a pitch adjustment method, a light source unit (1, 1 ′, 2, 3, 3 ′ is one unit) is rotated around an axis perpendicular to the main scanning direction and the sub-scanning direction. There is a method, but in this case, it is possible to set a desired pitch in one photoconductor, but in the other photoconductor, the shape error of the optical element after the light beam splitting element (light beam splitting means), the mounting error, etc. Causes a pitch error.
In order to solve this problem, it is necessary to provide means for adjusting the pitch in the sub-scanning direction between the beam splitter 4 and the deflecting means 7.

Since the cylindrical lens 5 is an anamorphic optical element, the beam waist diameter increases due to an eccentric error around the axis parallel to the optical axis, an arrangement error in the sub-scanning direction, and an eccentricity around the axis parallel to the main scanning direction. Further, adjustment in the optical axis direction is necessary for adjusting the beam waist position in the sub-scanning direction.
Therefore,
(1) Eccentricity adjustment around an axis parallel to the optical axis (2) Sub-scanning arrangement adjustment (3) Eccentricity adjustment around an axis parallel to the main scanning direction (4) Beam spot if adjustment in the optical axis direction can be performed simultaneously The diameter can be reduced, the beam spot position deviation can be reduced, the tolerance of parts of the optical element can be relaxed, and the cost can be reduced.

An example is shown in FIGS. The cylindrical lens 5 is attached to the housing 33 of the optical scanning device via an intermediate member 32. The intermediate member 32 has a triangular prism shape, and includes a flat portion 32 a that contacts the cylindrical lens 5 and a flat portion 32 b that is orthogonal to the flat portion 32 a and contacts the housing 33.
The cylindrical lens 5 has one end in the longitudinal direction fixed to the intermediate member 32 in a cantilever manner, but in the state before being fixed to the flat portion 32a of the intermediate member 32, the sub-scanning direction. Arrangement adjustment (in the direction of arrow D1) and eccentric adjustment around an axis parallel to the optical axis (in the direction of arrow D2) are possible.

In other words, the intermediate member 32 has a flat surface portion 32a that is a plane perpendicular to the optical axis of the cylindrical lens 5, thereby adjusting the eccentric direction around the optical axis of the cylindrical lens 5 and the optical axis. The vertical direction can be adjusted.
As shown in FIG. 22, the intermediate member 32 is arranged in the optical axis direction in the state before being fixed with respect to the upper surface of the fixing convex portion 34 of the housing 33, in the main scanning direction (in the direction of arrow D <b> 3). ) And the eccentricity adjustment around the axis parallel to the sub-scanning direction (arrow D4 direction). The intermediate member 32 is formed of a transparent material (for example, a plastic material).

Therefore, there are two or more adjustable directions of the cylindrical lens 5 with respect to the intermediate member 32, and there are two or more adjustable directions of the intermediate member 32 with respect to the housing 33.
Further, at least one of the directions in which the intermediate member 32 can be adjusted with respect to the housing 33 is different from at least one of the directions in which the cylindrical lens 5 can be adjusted with respect to the intermediate member 32.
By adopting such a support configuration, a plurality of optical characteristics (thickening the beam waist diameter, reducing beam waist position deviation, and beam spot position deviation) can be secured at the same time, and the cylindrical lens 5 is rotated around the optical axis. By making the eccentricity adjustable, the scanning line interval in the sub-scanning direction can be set optimally.
In FIG. 8, reference numerals 36 and 37 denote adhesive application surfaces (fixed surfaces or fixed surfaces).

An actual adjustment method will be described with reference to FIG. The cylindrical lens 5 is held by a jig (not shown), and the cylindrical lens 5 is moved in the direction to be adjusted (here, the position in the optical axis direction, the eccentricity around the axis parallel to the optical axis, the position in the sub-scanning direction).
Thereafter, the intermediate member 32 coated with the ultraviolet curable resin on the coating surface 36 is pressed against the flat surface portion 5a of the cylindrical lens 5 and the coating surface 37 of the housing 33 coated with the ultraviolet curable resin on the coating surface 37 (temporarily fixed). The cylindrical lens 5 and the intermediate member 32 are fixed by irradiating ultraviolet rays.
Since the intermediate member 32 is formed of a transparent material, the degree of freedom of ultraviolet irradiation is large and easy, and fixing can be performed quickly and uniformly.

In the above example, the cylindrical lens 5 is fixed to the one intermediate member 32 by the cantilever method. However, the cylindrical lens 5 may be fixed to the plurality of intermediate members 32. This example is shown in FIGS.
As shown in FIG. 9, in other words, the dimensions of the outer shape of the cylindrical lens 5 are long in the main scanning direction and the sub-scanning direction so that the light beams passing through the cylindrical lens 5 are positioned opposite to each other. Two intermediate members 32 are arranged at an interval in one direction (here, the sub-scanning direction), and each end of the cylindrical lens 5 is fixed to each flat surface portion 32a.
One intermediate member 32 is fixed to the upper surface of the convex portion 34 of the housing 33, and the other intermediate member 32 is fixed to the upper surface of the convex portion 35.
As in the above example, after fixing the cylindrical lens 5, the intermediate member 32 is brought into contact and irradiated with ultraviolet rays.
By adopting such a fixing (supporting) configuration, for example, when the linear expansion coefficient of the housing 33 and the intermediate member (here, synthetic resin) 32 is different, the optical axis is optically affected even if the temperature rises. Since stress is generated at the symmetrical portion of the element (cylindrical lens 5), the change in the attitude of the optical element due to temperature fluctuation is reduced.
Further, by adopting a configuration in which two intermediate members 32 are arranged at intervals in the direction of the longer outer shape of the cylindrical lens 5 in the main scanning direction and the sub-scanning direction, the tolerance for the arrangement error is obtained. Can be improved and the eccentric error can be reduced.

A second embodiment will be described with reference to FIGS. 11 and 12. In addition, the same part as the said embodiment is shown with the same code | symbol, and unless it was especially required, the description on the structure and function which were already demonstrated is abbreviate | omitted, and only the principal part is demonstrated.
As shown in FIG. 11, when the intermediate member 32 is fixed to the housing 33 so that the eccentric adjustment around the axis parallel to the sub-scanning direction is possible, the linear expansion of the housing 33 and the intermediate member 32 is performed. When the coefficients are different, the optical element 5 is decentered in the direction of the arrow 35 in the direction of the arrow 35 due to the temperature rise.
In order to solve this problem, in the present embodiment, as shown in FIG. 12, the intermediate member 32 is fixed to the housing 33 so as to be able to adjust the eccentricity around an axis parallel to the main scanning direction. That is, the intermediate member 32 is fixed to the vertical portion 33 a of the housing 33. The receiving surface of the housing 33 on which the intermediate member 32 is mounted is substantially perpendicular to the main scanning direction.
In this configuration, by mounting the intermediate member 32 and the optical element 5 at the center in the sub-scanning direction, even if the intermediate member 32 is deformed due to a temperature rise, as shown by the arrow 36, the optical element 5 Fluctuates in the main scanning direction, but is not decentered in the optical axis rotation direction.

Based on FIG. 13, a tandem type multicolor image forming apparatus using the above-described optical scanning device (opposing scanning type) will be described (third embodiment).
The multicolor image forming apparatus has four photoconductors 12Y, 12C, 12M, and 12K juxtaposed along the moving direction of the transfer belt 11. Around the photoreceptor 12Y for yellow image formation, a charger 13Y, a developer 14Y, a transfer unit 15Y, and a cleaning unit 16Y are arranged in this order in the rotation direction indicated by the arrow. Other colors also have the same configuration, and are distinguished by adding European letters (C: cyan, M: magenta, K: black) for each color, and a description thereof is omitted.
The charger 13 is a charging member constituting a charging device for uniformly charging the surface of the photoreceptor. Between the charging unit 13 and the developing unit 14, the surface of the photosensitive member is irradiated with a beam by the optical scanning device 20, and an electrostatic latent image is formed on the photosensitive member 12.
Based on the electrostatic latent image, a toner image is formed on the surface of the photoreceptor by the developing device 14. The transfer unit 15 sequentially transfers the transfer toner images of the respective colors onto the recording medium (transfer sheet) conveyed by the transfer belt 11, and finally the superimposed image is fixed on the transfer sheet by the fixing unit 17.
Here, a tandem image forming apparatus having a plurality of scanning optical systems is shown, but it goes without saying that the present invention can also be applied to an optical scanning apparatus having only one scanning optical system.

1 is a perspective view of an optical scanning device according to a first embodiment of the present invention. It is a figure which shows the function of a light beam splitting means. It is a schematic diagram which shows shielding one of the several beam from a common light source. It is a figure in the case of all lighting by the time chart of the system exposed using a common light source. It is a time chart of the method of exposing with a common light source, and is a diagram showing a state in which the set light amount is switched for each scanned surface. It is a general | schematic top view which shows the beam path of a counter scanning type | mold multi-beam system. It is a perspective view which shows the fixed state of a cylindrical lens and an intermediate member. It is a perspective view which shows the fixed state of the intermediate member with respect to a housing. It is a perspective view which shows the fixed state of the cylindrical lens and intermediate member in another example. FIG. 10 is a perspective view illustrating a fixed state of an intermediate member with respect to the housing in the example of FIG. 9. It is a figure which shows the concern regarding the fixing method of the intermediate member with respect to the housing in 1st Embodiment. It is a perspective view which shows the fixed state of the intermediate member with respect to the housing in 2nd Embodiment. FIG. 10 is a diagram illustrating a third embodiment, and is a schematic configuration diagram of a tandem type image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 'Semiconductor laser as light source 4 Half mirror prism as light beam splitting means 5 Cylindrical lens as anamorphic optical element 7 Deflection means 7a, 7b Polyhedral reflecting mirror 8 Scanning lens 1 as scanning optical system
9 Mirror as scanning optical system 10 Scanning lens 2 as scanning optical system
18 Write control section as light quantity correction means or beam spot position correction means 20 Optical scanning device 32 Intermediate member 33 Housing

Claims (12)

A light source;
A coupling optical system for coupling a beam from the light source;
An anamorphic optical element that condenses the light beam from the coupling optical system at least in the sub-scanning direction;
A plurality of multi-surface reflecting mirrors, and the multi-surface reflecting mirrors of different steps are offset from each other in the rotational direction, and deflecting means having a common rotation axis;
A beam splitting means for splitting a beam from a common light source and for allowing the split beam to enter the reflecting mirrors of the different stages;
A scanning optical system for guiding the beam scanned by the deflecting means to the surface to be scanned;
A housing for holding the light source and the deflecting means;
An optical scanning device in which beams divided from the common light source scan different scanning surfaces,
An optical scanning device characterized in that at least one of the anamorphic optical elements is attached to the housing via an intermediate member and is adjustable. The optical scanning device according to claim 1,
The intermediate member is adjustable relative to the housing, the anamorphic optical element is adjustable relative to the intermediate member, and the intermediate member is adjustable relative to the housing An optical scanning device characterized in that at least one of the possible directions and at least one adjustable direction of the anamorphic optical element with respect to the intermediate member are different. 3. The optical scanning device according to claim 1, wherein the following conditions are satisfied.
(1) The outer shape of the anamorphic optical element is longer in the main scanning direction than in the sub-scanning direction.
(2) The receiving surface of the housing on which the intermediate member is mounted is substantially perpendicular to the main scanning direction.
(3) The anamorphic optical element is attached to an intermediate member around the main scanning direction. The optical scanning device according to claim 3.
The optical scanning device according to claim 1, wherein the intermediate member is mounted at a substantially center of the anamorphic optical element in a sub-scanning direction. The optical scanning device according to claim 1 or 2,
There are a plurality of the intermediate members, and the optical scanning device is disposed on opposite sides of a light beam passing through the anamorphic optical element. The optical scanning device according to claim 5,
The optical scanning device according to claim 1, wherein the intermediate members are arranged in a direction having a longer outer shape in the main scanning direction and the sub-scanning direction of the anamorphic optical element. The optical scanning device according to any one of claims 1 to 6,
The intermediate scanning member has two flat portions orthogonal to each other. The optical scanning device according to any one of claims 1 to 7,
The optical scanning device characterized in that the intermediate member is fixed to the housing via an adhesive, and the anamorphic optical element is fixed to the intermediate member via an adhesive. The optical scanning device according to claim 8.
The optical scanning device according to claim 1, wherein the intermediate member is fixed to the housing via an adhesive, the intermediate member is transparent, and the adhesive is an ultraviolet curable resin. A light source;
A coupling optical system for coupling a beam from the light source;
An anamorphic optical element that condenses the light beam from the coupling optical system at least in the sub-scanning direction;
A plurality of multi-surface reflecting mirrors, and the multi-surface reflecting mirrors of different steps are offset from each other in the rotational direction, and deflecting means having a common rotation axis;
A beam splitting means for splitting a beam from a common light source and for allowing the split beam to enter the reflecting mirrors of the different stages;
A scanning optical system for guiding the beam scanned by the deflecting means to the surface to be scanned;
A housing for holding the light source and the deflecting means;
An optical scanning device in which beams divided from the common light source scan different scanning surfaces,
An optical scanning device characterized in that at least one of the anamorphic optical elements is centered on an axis parallel to the optical axis and is rotatable. The optical scanning device according to any one of claims 1 to 10,
An optical scanning device, wherein a plurality of beams scan the same scanned surface.   An image forming apparatus using the optical scanning device according to claim 1.

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