JP2004061746A - Light beam scanning optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light beam scanning optical device capable of image deterioration due to rotation unevenness and vibration associated with the rotation of a polygon mirror. <P>SOLUTION: The light beam scanning optical device 1 which deflects light beams emitted by light sources 4K, 4C, 4M, and 4Y by a rotating polygon mirror and shapes them in a given shape by an fθ lens 8 for scanning is characterized in that the light sources 4K, 4C, 4M, and 4Y are provided in a polygon chamber 16 where the polygon mirror 7 is installed with ribs 16a formed integrally with housings 2 and 3 separately from the fθ lens 8 and the polygon chamber 16 is partitioned with a straightening plate 17 surrounding the circumference of the polygon mirror 7. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light beam scanning optical device used in an image forming apparatus such as a color printer or a color copying machine, for scanning a plurality of light beams and guiding the light beams to a photosensitive drum or the like.
[0002]
[Prior art]
A conventional light beam scanning optical device mounted on an image forming apparatus such as a color printer or a color copier, for example, responds to black (BK), cyan (C), magenta (M), and yellow (Y) images. A plurality of light sources composed of semiconductor laser elements. The light sources corresponding to the respective colors emit light beams in different directions at predetermined timing.
[0003]
The light emitted from the light source is reflected in different directions for each light beam by a rotating polygon mirror, and is scanned on a plurality of separation mirrors corresponding to each light beam via an fθ lens that narrows the beam diameter to a predetermined size and shape. Is done. The light beam reflected by the separation mirror is reflected by the folding mirror, and is emitted through an imaging lens that forms an image of the light beam at a predetermined position.
[0004]
As a result, each of the plurality of photosensitive drums provided in the image forming apparatus is irradiated with each light beam, and a latent image corresponding to an image to be formed is formed on each photosensitive drum. Each of the above optical components is attached to a housing made of a resin molded product, and a plurality of light beams are emitted from an opening provided in the housing.
[0005]
[Problems to be solved by the invention]
However, according to the above-described conventional light beam scanning optical device, the polygon mirror rotates at a high speed, so that rotation unevenness and vibration accompanying the rotation occur. Therefore, the scanning of the light beam becomes unstable, and vibration is transmitted to the light source and the fθ lens provided near the polygon mirror. Accordingly, there is a problem that an image formed by the light emitted from the light beam scanning optical device is deteriorated.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a light beam scanning optical device capable of preventing image deterioration due to rotation unevenness and vibration accompanying rotation of a polygon mirror.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a light beam scanning optical device which deflects a light beam emitted from a light source by a rotating polygon mirror, shapes the light beam into a predetermined shape by an fθ lens, and scans the light beam. A polygon chamber for installing the polygon mirror, which is separated from the light source and the fθ lens, is provided by a rib integrally formed with the housing for covering the light beam scanning optical device, and facing the peripheral surface of the polygon mirror. A rectifying plate for rectifying an airflow caused by rotation is integrally formed with the rib, and the polygon chamber is further defined by the rectifying plate.
[0008]
According to this configuration, the plurality of light beams emitted from the light source are deflected by the polygon mirror arranged in the polygon chamber, and are scanned by narrowing the beam diameter to a predetermined size and shape by the fθ lens. The polygon chamber is surrounded by a rib integrally formed with the housing, and is provided to be isolated from the light source and the fθ lens. The polygon mirror is arranged in a space further defined by the rectifying plate. Accordingly, rotation unevenness due to rotation of the polygon mirror is reduced by the rectifying plate, and transmission of vibration to the light source and the fθ lens is suppressed.
[0009]
Further, the present invention is characterized in that, in the light beam scanning optical device having the above configuration, the outside and the inside of the rectifying plate communicate with each other via the upper side of the polygon mirror. According to this configuration, the heat generated by the drive motor of the polygon mirror is emitted to the outside of the rectifying plate via the upper portion of the polygon mirror.
[0010]
According to the present invention, in the light beam scanning optical device having the above-described configuration, the height of the rib is higher than that of the rectifying plate.
[0011]
According to the present invention, in the optical beam scanning optical device having the above-described configuration, the polygon mirror is mounted on a driving substrate that drives the polygon mirror. According to this configuration, the card-type polygon having the polygon mirror mounted on the drive board is provided, and heat generated by the electronic components mounted on the drive board is emitted to the outside of the rectifying plate via above the polygon mirror.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are a side sectional view and a top sectional view showing a light beam scanning optical device according to an embodiment. The light beam scanning optical device 1 is mounted on an image forming apparatus such as a color printer or a color copying machine, and is covered at the top and bottom by first and second housings 2 and 3 made of resin molded products.
[0013]
A light source chamber 15 is provided on one side of the first housing 2. The light source room 15 includes a plurality of light sources 4K, 4C, 4M, and 4Y composed of semiconductor laser devices that emit light beams corresponding to black (BK), cyan (C), magenta (M), and yellow (Y) images. Is arranged. The light sources 4K, 4C, 4M, and 4Y corresponding to the respective colors emit light beams in different directions in the vertical direction at predetermined timing.
[0014]
The light sources 4K, 4C, and 4M are arranged so that the direction of the emitted light is substantially perpendicular to the direction of the emitted light of the light source 4Y, and reflect the emitted light of the light sources 4K, 4C, and 4M to reflect the emitted light of the light source 4Y. Reflection mirrors 5K, 5C, and 5M that substantially match the directions are provided. A reflection mirror 6 is provided in the emission direction of the light source 4Y, and a cylinder lens 9 for condensing the light beam reflected by the reflection mirror 6 is provided in the reflection direction of the reflection mirror 6.
[0015]
On the same side as the light source chamber 15, a polygon chamber 16 is provided adjacent to the light source chamber 15 and surrounded by a rib 16 a formed integrally with the first housing 2. The polygon chamber 16 is provided with a rotating polygon mirror 7. The polygon mirror 7 is mounted on a drive board 18 (see FIG. 3) together with a drive motor 7a (see FIG. 3). Thus, a so-called card-type polygon integrated with the drive board 18 is used to save space. The driving of the drive motor 7a rotates the polygon mirror 7, and the incident light of the polygon mirror 7 is reflected and deflected.
[0016]
On the side of the polygon chamber 16, an fθ lens 8 for narrowing the beam diameter of the reflected light from the polygon mirror 7 to a predetermined size and shape is provided. Thus, the light beam is scanned in the main scanning direction (up and down direction in FIG. 2) in a predetermined shape. Further on the side of the fθ lens 8, a plurality of separation mirrors 10K, 10C, 10M, and 10Y that reflect a scanned light beam for each color are arranged.
[0017]
Under the light beam scanning optical device 1, folding mirrors 11K, 11C, and 11M that reflect the reflected light from the separation mirrors 10K, 10C, and 10M and guide the reflected light downward are provided. Imaging lenses 12K, 12C, 12M, and 12Y for imaging light beams corresponding to the respective colors at predetermined positions are attached to the second housing 3 below the folding mirrors 11K, 11C, and 11M and the separation mirror 10Y. On the lower surface of the second housing 3, openings 13K, 13C, 13M, and 13Y are formed below the imaging lenses 12K, 12C, 12M, and 12Y.
[0018]
A rectifying plate 17 facing the peripheral surface is provided around the polygon mirror 7. The current plate 17 is provided at two locations of the rib 16a so as to be integrally formed with the rib 16a, and further defines the polygon chamber 16. The airflow caused by the rotation of the polygon mirror 7 is rectified by the rectifying plate 17 to prevent uneven rotation.
[0019]
FIG. 3 shows a side sectional view of the polygon chamber 16. The upper part of the polygon mirror 7 surrounded by the current plate 17 is open, and the rib 16 a is formed higher than the current plate 17. For this reason, the air inside the rectifying plate 17 in the radial direction can flow out into the outer polygon chamber 16 via the upper side of the polygon mirror 7.
[0020]
In the optical beam scanning optical device 1 having the above configuration, the light beams emitted from the light sources 4K, 4C, and 4M are reflected by the reflection mirrors 5K, 5C, and 5M, and reach the reflection mirror 6 together with the light beams emitted from the light source 4Y. . The light beam reflected by the reflection mirror 6 is collected by the cylinder lens 9.
[0021]
The condensed light beam is reflected by the rotating polygon mirror 7, the beam diameter is narrowed down to a predetermined size and shape by the fθ lens 8, and the beam is scanned in the main scanning direction. Each light beam to be scanned is reflected by the separation mirrors 10K, 10C, 10M, and 10Y. Light reflected by the separation mirrors 10K, 10C, and 10M is reflected by the folding mirrors 11K, 11C, and 11M in the directions of the openings 13K, 13C, and 13M.
[0022]
The reflected light from the separation mirror 10Y and the reflected light from the folding mirrors 11K, 11C, and 11M are emitted from the openings 13K, 13C, 13M, and 13Y via the imaging lenses 12K, 12C, 12M, and 12Y. Light beams are imaged on a plurality of photosensitive drums 20K, 20C, 20M, and 20Y corresponding to respective colors provided in the image forming apparatus by the imaging lenses 12K, 12C, 12M, and 12Y. As a result, a latent image corresponding to the image to be formed is formed on each of the photosensitive drums 20K, 20C, 20M, and 20Y.
[0023]
According to the present embodiment, the polygon chamber 16 has a high rigidity surrounded by a narrow area by the rib 16a and is provided separately from the light sources 4K, 4C, 4M, 4Y and the fθ lens 8. Accordingly, transmission of vibration to the light sources 4K, 4C, 4M, 4Y and the fθ lens 8 can be reduced. Further, since the rib 16a is formed integrally with the first housing 2, the production cost is not increased.
[0024]
Further, since the polygon chamber 16 is further defined by the rectifying plate 17 integrally formed with the rib 16a, rotation unevenness of the polygon mirror 7 can be prevented, and rectifying a narrower range without increasing the manufacturing cost. The rigidity is improved by being surrounded by the plate 17, and the transmission of vibration can be further reduced.
[0025]
Further, the height of the rib 16a is made higher than that of the rectifying plate 17, and the radially outer side and the inner side of the rectifying plate 17 communicate with each other via the upper side of the polygon mirror 7, so that the heat generated by the drive motor 7a of the polygon mirror 7 is generated. To the outside of the current plate 17. Accordingly, heat does not accumulate in a narrow area surrounded by the rectifying plate 17, and image deterioration due to deformation of the first and second housings 2 and 3 and expansion of the polygon mirror 7 can be prevented. The upper part of the polygon mirror 7 may be opened as shown in FIG. 3, or a dustproof filter or the like may be provided as shown by a broken line D in FIG.
[0026]
Further, even if a card-shaped polygon is provided for saving space, heat generated by the electronic components mounted on the drive board 18 can be easily discharged to the outside of the rectifying plate 17. Therefore, deformation of the first and second housings 2 and 3 and expansion of the polygon mirror 7 can be further prevented.
[0027]
【The invention's effect】
According to the present invention, since the polygon chamber for disposing the polygon mirror is provided by the rib integrally formed with the housing, the polygon chamber has high rigidity and is isolated from the light source and the fθ lens, so that the manufacturing cost is not increased. The transmission of the vibration accompanying the rotation of the polygon mirror to the fθ lens and the light source can be reduced.
[0028]
In addition, the rectifying plate is resin-molded integrally with the ribs, and the polygon chamber is further defined by the rectifying plate, so that rotation unevenness of the polygon mirror can be prevented, and a narrower range can be rectified without increasing the manufacturing cost. The rigidity is improved by being surrounded by a plate, and the transmission of vibration can be further reduced. Therefore, it is possible to prevent deterioration of an image formed by the light beam scanning optical device.
[0029]
Further, according to the present invention, since the radially outer side and the inner side of the rectifying plate communicate with each other via the upper side of the polygon mirror, the heat generated by the drive motor of the polygon mirror can be released to the outside of the rectifying plate. Therefore, deformation of the housing and expansion of the polygon mirror can be prevented. In addition, by making the height of the rib higher than that of the current plate, the radially outer side and the inner side of the current plate can be easily communicated with each other.
[0030]
Further, according to the present invention, since a card-type polygon in which a polygon mirror is mounted on a drive board is provided, heat generated by electronic components mounted on the drive board can be released to the outside of the rectifying plate, and deformation of the housing and the polygon mirror can be prevented. Inflation can be further prevented.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a light beam scanning optical device according to an embodiment of the present invention.
FIG. 2 is a top sectional view showing a light beam scanning optical device according to an embodiment of the present invention.
FIG. 3 is a side sectional view showing a polygon chamber of the light beam scanning optical device according to the embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 light beam scanning optical device 2 first housing 3 second housing 4K, 4C, 4M, 4Y light source 5K, 5C, 5M reflection mirror 6 reflection mirror 7 polygon mirror 8 fθ lens 9 cylinder lens 10K, 10C, 10M, 10Y separation mirror 11K, 11C, 11M Folding mirrors 12K, 12C, 12M, 12Y Imaging lenses 13K, 13C, 13M, 13Y Opening 15 Light source room 16 Polygon room 16a Rib 17 Rectifying plate 18 Driving substrates 20K, 20C, 20M, 20Y Photoconductor drum

Claims (4)

A light beam scanning optical device for deflecting a light beam emitted from a light source by a rotating polygon mirror, shaping the light beam into a predetermined shape by an fθ lens, and scanning the light beam. A rib integrally formed with the light source and the fθ lens is provided with a polygon chamber in which the polygon mirror is installed. A light beam scanning optical device, wherein the polygon chamber is further defined by the rectifying plate while being integrally formed with a rib. 2. The light beam scanning optical device according to claim 1, wherein the outside and the inside of the rectifying plate communicate with each other via the upper side of the polygon mirror. The light beam scanning optical device according to claim 2, wherein the height of the rib is higher than that of the rectifying plate. The optical beam scanning optical device according to claim 2, wherein the polygon mirror is mounted on a drive substrate that drives the polygon mirror.

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