JP3386257B2 - Light beam scanning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam scanning device, and more particularly to a light beam scanning device using a rotating polygon mirror.

[0002]

2. Description of the Related Art Generally, an image forming apparatus includes an electrophotographic copying machine, a printer or a facsimile machine.
For image formation, the original on the original table is illuminated with light emitted from a light source, and the reflected light from the original is imaged on a photoconductor, which is one of the image carriers, using an imaging optical system. Alternatively, an electrostatic latent image can be written by scanning the photosensitive member with a light beam such as a laser beam on the basis of writing information such as an image signal input from the document reading unit in the image processing unit to perform writing scanning. An exposure process for forming an image is set. In the exposure process, an apparatus using a laser beam, which is one of the configurations used when forming an electrostatic latent image according to write information, includes a laser light source, a rotating polygon mirror,
An optical system including an fθ lens, a cylindrical lens, a mirror, and the like are provided, and a laser beam from a light source is scanned by a rotating polygon mirror to form an electrostatic latent image on a photoconductor.

Incidentally, the rotary polygon mirror is generally housed in a hermetically sealed container in order to prevent the mirror surface from being contaminated by dust or the like. Therefore, at the time of rotation, the air around the rotary polygon mirror is taken in the container to generate a rotary flow. When a rotating flow is generated in the air, if the volume inside the closed container is relatively large, not only the rotating load of the rotating polygon mirror increases due to the viscosity of the air, but also near the rotating polygon mirror and the inner wall surface of the closed container. Due to the difference in the moving speed with the existing air, the atmospheric temperature in the container rises, and further,
Wind loss is likely to occur, which also causes a temperature rise in the drive system.

Conventionally, as a structure for preventing windage loss, there is a structure described in (1) Japanese Utility Model Laid-Open No. 59-123821 and (2) Japanese Patent Laid-Open No. 58-46317. In the publication of (1), an inner wall surface is located in the vicinity of the rotation locus of the rotary polygon mirror to form a housing capable of hermetically sealing the rotary polygon mirror in a necessary minimum volume excluding the rotation locus. A configuration is shown in which a window for passing a laser beam is formed in a part of the housing. The publication of (2) shows a configuration in which a partition member that surrounds the periphery of the rotary polygon mirror by removing a portion through which the laser beam passes is provided around the rotary polygon mirror arranged in the closed container. There is.

Each of the configurations described in these publications is designed to suppress an increase in temperature in the housing portion of the rotary polygon mirror due to windage loss generated when the rotary polygon mirror rotates.

In recent years, printers and the like have been required to have a high density in addition to a high speed, and accordingly, the rotational speed of the rotary polygon mirror tends to increase.

When the rotational speed of the rotary polygon mirror is increased, in addition to the increase of the internal atmosphere temperature due to the increase of the wind loss, the noise due to the wind noise is often increased. The frequency (F) of noise in the rotary polygon mirror is obtained by F = (number of rotations) ÷ 60 (sec) × (number of mirror surfaces of the rotary polygon mirror). As a result, the higher the number of rotations, the easier it is to obtain a frequency that can be recognized as noise.

In the past, since low density / low speed rotation was the mainstream, the frequency of the wind noise of the rotating polygon mirror was suppressed to a relatively low value. For example, 1 per minute
300 DPI (11.8 lines / m) that can print 0 sheets
In order to realize m), assuming that the number of mirror surfaces of the rotary polygon mirror is eight, the number of rotations around 8000 rpm is sufficient, so that the generation of wind noise as noise was not felt so much.

However, in recent years, it has become possible to dramatically increase the number of rotations of the rotary polygon mirror due to the progress of the drive system for the rotary polygon mirror. For example, 40 prints per minute can be obtained. It is also becoming possible to achieve the possible 600 DPI density. In this case, the rotation speed is around 32000 rpm, and the wind noise associated therewith can be clearly recognized as noise.

Considering whether or not such noise can be prevented in the structure described in the above publication,
In any of the configurations described in any of the publications, wind noise cannot be suppressed. This is because, in the configurations described in the above publications, as shown in FIG. 11, the passage portion of the laser beam provided in the partition member A is formed by the opening portion B to which the transparent member D can be attached, and the rotation is performed. The edge B1 of the opening B located on the downstream side (the direction of the arrow in the drawing) of the polygonal mirror C in the rotational direction.
Is exposed in the air flow path, so that the edge portion B1
Air collides with the air, and not only the impact sound at this time is generated as noise, but also the wind noise that involves the turbulent flow of air generated at the time of collision is generated as large noise.

In view of the above problems in the conventional light beam scanning device, an object of the present invention is to provide a light beam scanning device having a structure capable of reducing noise even when equipped with a rotary polygon mirror capable of high-speed rotation. To provide.

[0012]

To achieve this object, the invention according to claim 1 forms an image of a rotary polygon mirror for reflecting and scanning a light beam using a laser beam or the like. In the light beam scanning device configured to include a lens / mirror for, it is arranged around the rotary polygon mirror and is formed with a curvature substantially the same as the rotation locus of the rotary polygon mirror. A part of the light beam which is partially removed to allow the light beam to enter and be reflected by the rotating polygon mirror is formed, and a partition member surrounding the rotating polygon mirror except for the passing part, and a partition member of the partition member. A transparent member formed to have a size to cover the passage portion, the transparent member being downstream in the rotation direction of the rotary polygon mirror.
The end corresponding to the side to the partition member facing this end
Placed in the step formed at the end of the passage part,
The step and the position where it is laminated on the surface of the transparent member itself
It is characterized in that it is sandwiched and arranged by a deciding member .

According to a second aspect of the present invention, the positioning member is provided.
Is a partition located upstream of the rotary polygon mirror in the direction of rotation.
It is characterized by being positioned flush with the inner wall surface near the passage portion of the material .

According to a third aspect of the present invention, the transparent member is
It is extended tangentially to the rotation trajectory of the rotating polygon mirror.
It is composed of a straight transparent plate, and
The downstream end of the rotary polygon mirror in the rotation direction is the above-mentioned rotary polygon mirror.
In the vicinity of the opening edge of the passage part corresponding to the downstream side in the rotation direction of
It is characterized in that it is positioned on the wall surface side .

According to a fourth aspect of the present invention, a laser beam or the like is used.
The same as the rotating polygon mirror for scanning the used light beam,
With a lens mirror for focusing the light beam
In the configured light beam scanning device,
It is arranged around the face mirror and the
It is formed with the same curvature as the trace, and part of the wall is removed.
And the light beam is incident on and reflected by the rotating polygon mirror.
The passing part of the light beam is formed, except for the passing part
A partition member surrounding the rotating polygon mirror, and the partition member
Transparent that is formed in a size that covers the passage part
And a transparent member having a linear shape that is tangentially extended with respect to the rotational trajectory of the rotary polygonal mirror, and the end of the rotary polygonal mirror in the extension direction on the downstream side in the rotational direction. The portion is positioned on the inner wall surface side near the opening edge of the passage portion corresponding to the downstream side in the rotation direction of the rotary polygon mirror.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

According to the first and second aspects of the present invention, since the transparent member is sandwiched by the positioning members, fluttering due to wind pressure generated when the rotary polygon mirror is rotated can be suppressed even when a thin transparent member is used. Moreover, the end portion of the positioning member is continuous with the inner wall surface of the partition member, and the step portion forming the opening edge of the passage portion of the partition member is covered, so that it is not exposed in the air flow path.

According to the third aspect of the invention, even when the transparent member is expanded and displaced by thermal expansion, the holding by the positioning member is maintained.

According to the fourth aspect of the present invention, the transparent member is a linear member, and the transparent member located on the downstream side in the rotation direction of the rotary polygon mirror is on the inner wall surface side of the partition member. It is continuous with the wall surface and does not hinder the flow of air due to the rotation of the rotating polygon mirror.

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic diagram for explaining a schematic configuration of a light beam scanning device showing an embodiment of the present invention. Figure 1
In FIG. 1, the light beam scanning device 1 includes a belt-shaped photoconductor (hereinafter, referred to as a photoconductor belt) 2 wound around a pulley 2A as a photoconductor used as one of image carriers, and an axis of the pulley 2A. Direction as the main scanning direction,
The configuration is such that spotwise image formation is performed in each direction with the rotation direction of the photosensitive drum 2 as the sub-scanning direction. The light beam device 1 shapes the outgoing beam modulated by the image signal from the semiconductor laser unit 3 by the aperture 4 and then repeatedly deflects it in the main scanning direction of the photoconductor 2 by the rotary polygon mirror 5 to form an imaging lens 6, An image is formed in a spot shape on the photosensitive belt 2 via the mirror 7 and the cylindrical lens 8 to scan in the main scanning direction. In the scanning in the sub-scanning direction, the scanning position is determined by the rotation of the photosensitive belt 2, and the scanning in the main scanning direction is performed again at that position, so that the electrostatic latent image is formed in each scanning direction. An image is formed.

The rotary polygonal mirror 5 is housed in a closed container (not shown) in FIG. 2, and a partition member 9 is arranged in the vicinity of its rotation locus. As shown in FIG. 2, the partition member 9 is formed of a cylindrical member having substantially the same curvature as the rotation trajectory of the rotary polygon mirror 5, and a part of its peripheral wall is formed of a window capable of emitting a light beam. A beam passing portion 9A is provided. The passing portion 9A has a circumferential length that allows the beam to be emitted from one mirror surface of the rotary polygon mirror 5 over the entire area in the main scanning direction.

Passing portion 9A on the inner wall surface of the partition member 9
A transparent member 10 is arranged in the. Transparent member 10
As shown in FIG. 3, a relatively thin film resin material such as acrylic having a size capable of covering the passage portion 9A is used, and is formed to have a diameter substantially the same as the inner diameter of the partition member 9, Both ends of the rotary polygonal mirror 5 along the rotation direction and the upper and lower ends in the direction perpendicular to the rotation direction are attached and attached to the periphery of the passing portion 9A. In particular, the end portion of the rotary polygonal mirror 5 located on the downstream side in the rotation direction is attached to the inner wall surface of the partition member 9 in the vicinity of the passing portion 9A. As a result, the opening edge 9 in the passage portion 9A, which is the position where air collides when the rotary polygon mirror 5 rotates.
The inner wall surface of A1 will be blocked. The thickness of the transparent member 10 is such that turbulent air flow does not occur at the upstream and downstream ends of the rotary polygon mirror 5 in the rotational direction when the air flow occurs when the rotary polygon mirror 5 rotates. The thickness of the partition member 9 is set so that it can flow continuously and maintain a so-called laminar flow state.
It is formed to be extremely thin compared to the thickness of the peripheral wall.

Since this embodiment has the above-mentioned configuration,
The inner wall surface side of the opening edge 9A1 of the passage portion 9A in the partition member 9 is covered with the transparent member 10, and the partition member 9 is not exposed. As a result, the air flowing when the rotary polygon mirror 5 rotates does not collide with the opening edge 9A1 of the partition member 9 located on the downstream side in the rotation direction of the rotary polygon mirror 5, and maintains a so-called laminar flow state. Therefore, the generation of noise such as collision noise is suppressed. Moreover, since the transparent member 10 is pressed against the inner wall surface of the partition member 9 by the wind pressure generated when the rotary polygon mirror 5 rotates, the transparent member 10 is more firmly fixed. Although the partition member 9 has a cylindrical shape, as shown in FIG. 4, the partition member 9 is closed by providing a lid 9B and a ceiling so as to block the leakage of wind noise to the outside. May be.

The transparent member 10 is not only mounted and mounted on the inner wall surface near the opening edge of the passage portion 9A of the partition member 9, but also at the opening edge 9A1 located on the downstream side in the rotation direction of the rotary polygon mirror 5. It is also possible to form a step and drop it into the step so as to be flush with the inner wall surface of the partition member 9 near the opening edge. Thereby, the laminar flow state of air can be further promoted.

As a modification of the structure in which the transparent member is arranged by providing a step at the opening edge of the passage portion 9A, there is a case where the transparent member 11 shown in FIG. 5 is used. Transparent member 11 shown in FIG.
Is made of glass having a shape substantially similar to that of the partition member 9. In the case of glass, unlike the resin materials used in the above-mentioned examples, it cannot be made very thin.
Therefore, as shown in FIG. 6, the passage portion 9A of the partition member 9
At the opening edge 9A on the upstream side in the rotation direction of the rotary polygon mirror 5
2 is provided with a step portion, one end portion of the transparent member 11 is fitted in the step portion, and the other end portion is provided in the vicinity of the opening edge 9A1 of the passage portion 9 located on the downstream side in the rotation direction of the rotary polygon mirror 5. It is mounted and fixed on the inner wall surface of the partition member 9.

According to this structure, the opening edge 9A1 in the passage portion 9A of the partition member 9 is similar to the above embodiment.
Is blocked by the transparent member 11, and the air when the rotary polygon mirror 5 rotates does not collide with the opening edge 9A1. Moreover, even when a relatively thick material is used, by making the end surface flush with the inner wall surface of the partition member on the upstream side in the rotation direction of the rotary other-surface mirror 5, air collision at this portion is achieved. Since it can be avoided, it is possible to further secure the laminar flow state of air. Further, since the transparent member 11 is made of glass, the transmission of the beam can be ensured, and the transparent member 11 has a certain weight to suppress the vibration caused by the wind pressure generated when the rotary polygon mirror 5 rotates, and thus the resonance frequency. It is possible to reduce the noise, and also by this, it is possible to prevent the vibration due to the fluttering of itself and suppress the generation of noise.

By the way, as a structure for preventing the transparent member from fluttering due to wind pressure due to the rotation of the rotary polygon mirror 5, there is a structure shown in FIG. FIG. 7 shows a case where the film-shaped transparent member 10 shown in FIG. 3 is used. In this case, the partition member 9 is sandwiched between the step portion formed in the passage portion 9A and the positioning member 12. It has become so. A step portion 9A3 for making the transparent member 10 and the positioning member 12 flush with the inner wall surface in the vicinity of the opening edge 9A2 when the transparent member 10 and the positioning member 12 are inserted into the opening edge 9A2 on the upstream side in the rotation direction of the rotary polygon mirror 5 in the passing portion 9A. Are formed. The transparent member 10 and the positioning member 12 are laminated in this order in the stepped portion 9A3, and the positioning member 12 sandwiches the upper and lower ends of the transparent member 10 as shown in FIG. . Further, the length of the positioning member 12 is transparent up to the end located on the downstream side in the rotation direction of the rotary polygon mirror 5 corresponding to the position opposite to the end entering the step portion 9A3 with respect to the length of the transparent member 10. The length of the member 10 is longer than that of the member 10, and the end of the member 10 is fixed to the inner wall surface of the partition member 9. As a result, the transparent member 10 is configured such that the end portion on the downstream side in the rotation direction of the rotary polygon mirror 5 can be displaced in the length direction thereof. In such a configuration, the transparent member 10 and the positioning member 12 close the opening edge 9A1 of the passage portion 9A located on the downstream side in the rotation direction of the rotary polygon mirror 5. Therefore, the air flow generated by the rotation of the rotary polygon mirror 5 is maintained in a laminar flow state without colliding with the opening edge 9A1. Moreover, when the ambient temperature in the partition member 9 rises, the transparent member 10 may expand, but the expansion of the end portion of the transparent member 10 due to the expansion causes a difference in length between the transparent member 10 and the positioning member 12. Since it is absorbed by the difference, it is prevented from falling off from the passing portion 9A and is prevented from being deformed.

The transparent member 10 can be integrally formed with the partition member 9. FIG. 9 shows a configuration in this case. The partition member 9 and the transparent member 10 are formed of the same material, and a portion corresponding to the transparent member 10 is a transparent portion thinner than other portions. The location is configured as a colored portion. Moreover, the portion corresponding to the transparent member 10 is formed by extending the inner wall surface of the partition member 9. As a result, the transparent member 10 is continuously formed integrally with the inner wall surface of the partition member 9 at a portion corresponding to the passage portion 9A of the partition member 9, so that the opening edge of the passage portion 9A1 is closed. Air can be maintained in a laminar flow state without causing the air flow generated when the rotary polygon mirror 5 rotates to collide with the opening edge 9A1.

The transparent member is not limited to have substantially the same curvature as that of the partition member 9 as shown in the above configuration.
FIG. 10 shows the configuration in this case, and the transparent member 13
Is aligned with the tangential direction of the rotation trajectory of the rotary polygon mirror 5, and is preferably formed in a straight line parallel to the mirror surface of the rotary polygon mirror 5. The material of the transparent member 13 in this case may be resin or glass. The transparent member 13 is inserted into the stepped portion 9A4 formed on the inner wall surface of the partition member 9 at the end of the passing portion 9A of the partition member 9 on the downstream side in the rotation direction of the rotary polygon mirror 5, and the transparent member 13 is inserted. The end face of the rotary polygonal mirror 5 on the upstream side in the rotation direction is attached to a support part 9B formed by protruding a part of the peripheral wall of the partition member 9 to the outside. There is. The support portion 9B is
The transparent member 1 is tangential to the rotation trajectory of the rotary polygon mirror 5.
It is provided to set the orientation of No. 3, and the amount of protrusion from the peripheral wall of the partition member 9 that satisfies this requirement is set. The end of the transparent member 13 located on the downstream side in the rotation direction of the rotary polygon mirror 5 is not inserted into the stepped portion 9A4 of the partition member 9 to be flush with the inner wall surface of the partition member 9,
The partition member 9 may be mounted and fixed on the inner wall surface near the opening edge of the passage portion 9A.

In such a structure, the transparent member 13 closes the opening edge 9A1 on the downstream side of the rotary polygonal mirror 5 in the passage portion 9A of the partition member 9 in the rotational direction, so that when the rotary polygonal mirror 5 rotates. The generated air flow is at the opening edge 9A1.
Never collide with. Moreover, since the volume on the upstream side of the rotary polygon mirror 5 in the rotation direction is recessed from the wall surface without the partition member 9 to expand the volume, it is possible to expand the air flow to some extent to reduce the speed of the air flow and muffle the sound. Become. In addition, since the transparent member 13 is a linear member, it has good workability.

[0043]

As described above, according to claim 1 and
According to the second aspect of the invention, since the transparent member is sandwiched by the positioning members, even if a thin transparent member is used, fluttering due to wind pressure generated when the rotary polygon mirror rotates can be suppressed. In addition, since the end of the positioning member is continuous with the inner wall surface of the partition member, the opening edge of the passage portion of the partition member is covered, and the state where it is not exposed in the air flow path is maintained, suppressing noise generation. can do.

According to the third aspect of the present invention, since the nipping by the positioning member is maintained even when the transparent member is expanded and displaced by thermal expansion, the state in which the transparent member closes the opening edge of the passing portion is maintained, and the air is maintained. Can be maintained in a laminar flow state to reduce noise generation.

According to the fourth aspect of the present invention, the transparent member is constituted by the linear member having a shape that is relatively easy to process, and the transparent member located on the downstream side in the rotation direction of the rotary polygon mirror is the partition member. Since it is on the inner wall surface side, it does not interfere with the air flow due to the rotation of the rotating polygon mirror, so it is possible to suppress the generation of noise even if the transparent member has a simple structure. It will be possible.

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a schematic configuration of a light beam device according to an embodiment of the present invention.

2 is a perspective view showing an example of an installation structure of a rotary polygon mirror used in the light beam device shown in FIG.

FIG. 3 is a cross-sectional view of the installation structure shown in FIG.

FIG. 4 is a perspective view showing a partially modified example of the installation structure shown in FIG.

5 is a perspective view showing a modified example of a member used for the installation structure of the rotary polygon mirror in the light beam scanning device shown in FIG.

6 is a cross-sectional view showing an example of an installation structure of a rotary polygon mirror to which the member shown in FIG. 5 is applied.

7 is a cross-sectional view showing another modified example of the installation structure of the rotary polygon mirror used in the light beam scanning device shown in FIG.

FIG. 8 is an exploded perspective view of the modified example shown in FIG.

9 is a perspective view showing another modified example of the installation structure of the rotary polygon mirror used in the light beam scanning device shown in FIG.

10 is a cross-sectional view showing still another modified example of the installation structure of the rotary polygon mirror used in the light beam scanning device shown in FIG.

FIG. 11 is a cross-sectional view showing a conventional example of an installation structure of a rotary polygon mirror used in a light beam scanning device.

[Explanation of symbols]

1 Light Beam Scanning Device 5 Rotating Polygonal Mirror 9 Partitioning Member 9A Passing Portion 9A1 Opening Edge 9A2 of Passing Portion Downstream of Rotating Polygonal Mirror in Rotating Direction 9A3 , 9A4 Step 10 Transparent member 11 Transparent member 12 Positioning member 13 Transparent member

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 26/10

Claims (4)

(57) [Claims] 1. A light beam scanning device comprising a rotary polygon mirror for reflecting and scanning a light beam using a laser beam and the like, and a lens mirror for focusing the light beam, It is arranged around the rotary polygon mirror and is formed with a curvature substantially the same as the rotation trajectory of the rotary polygon mirror, and a part of the wall is removed so that the light beam is incident on the rotary polygon mirror.
A partition member that forms a passage portion of the reflected light beam and surrounds the rotary polygon mirror except the passage portion, and a transparent member that is formed to have a size that covers the passage portion of the partition member. The transparent member is disposed in a step portion formed at an end portion of a passage portion of the partition member, the end portion corresponding to a rotation direction downstream side of the rotary polygon mirror facing the end portion, and the step thereof. A light beam scanning device, wherein the light beam scanning device is disposed so as to be sandwiched by a portion and a positioning member laminated on the surface of the transparent member itself. 2. The light beam device according to claim 1, wherein the positioning member is positioned flush with an inner wall surface near a passage portion of a partition member located upstream of the rotary polygon mirror in the rotation direction. And a light beam scanning device. 3. The light beam scanning device according to claim 1, wherein the positioning member has a longer end in the rotational direction of the rotary polygon mirror than the end of the transparent member facing the end. A light beam scanning device having an end portion attached to an inner wall surface of the partition member. 4. A light beam using a laser beam or the like is reflected
A rotating polygon mirror for inspection and an image of the same light beam.
Light beam configured with a lens mirror for
In the scanning device, the rotary polygon mirror is arranged around the rotary polygon mirror.
It is formed with the same curvature as the rotation trajectory of the mirror,
Part is removed and the light beam is incident on the rotating polygon mirror.
The passing part of the reflected light beam is formed, and the passing part
The partition member surrounding the rotary polygonal mirror except for the portion and the size of the partition member passing through the partition member are provided.
And a transparent member that is formed of a linear transparent plate that is tangentially extended with respect to the rotation trajectory of the rotary polygonal mirror, and the direction of rotation of the rotary polygonal mirror in the extension direction. A light beam scanning device characterized in that an end portion on a downstream side is positioned on an inner wall surface side near an opening edge of a passage portion corresponding to a downstream side in a rotation direction of the rotary polygon mirror.