JPH10246864A - Light deflection scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the contamination of a rotary polygon mirror by providing a cover member with a rib-like member surrounding the rotary polygon mirror and an entire driving means. SOLUTION: When both of an optical box 6 and the cover member 10 are moldings, a space between the box 6 and the member 10 can not be completely hermetically sealed due to the warpage of the member 10. In order to prevent such a situation, a cover rib 10a being the rib-like member is integrally formed on the inside of the member 10. The cover rib 10a of the member 10 is disposed to surround an entire motor base plate 12 and constituted so that the lower end of the rib 10a may be positioned under the base plate 12. By perfectly covering the rotary polygon mirror 3, a stator 13 and a rotor 14 constituting a motor 3a for the mirror 3 and the base plate 12 with the cover rib 10a, outside air entering from the space between the box 6 and the member 10 is shut out so as to prevent the contamination of the mirror 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light deflection scanning device used for an image forming apparatus such as a laser printer and a laser facsimile.

[0002]

2. Description of the Related Art As shown in FIG. 9, a light deflection scanning device used for an image forming apparatus such as a laser printer or a laser facsimile machine collimates a laser beam generated from a semiconductor laser 101 by a collimator lens 102a and an aperture 102b. After adjusting the beam shape, the light is condensed into a linear light beam by the cylindrical lens 102c, and is rotated by the rotary polygon mirror 103 to a predetermined direction perpendicular to the direction along the rotation axis (hereinafter, referred to as “Z-axis direction”). The beam is deflected and scanned in a direction (hereinafter, referred to as “Y-axis direction”), and forms an image on a photoconductor on a rotating drum 105 via an imaging lens system 104. The light beam formed on the photoreceptor forms an electrostatic latent image with the main scanning in the Y-axis direction by the rotation of the rotating polygon mirror 103 and the sub-scanning in the Z-axis direction by the rotation of the rotating drum 105.

In this manner, the scanning for writing the image information on the photosensitive drum of the rotating drum 105 is repeated, but the writing position on the rotating drum 105 may be shifted due to the division error of the reflection surface of the rotating polygon mirror 103. There is. Therefore, the scanning light L ₀ of the rotating polygon mirror 103 is transmitted to the scanning plane (X
At one end in the Y-axis direction (Y plane), the light is separated by the BD mirror 106 below the scanning surface,
a into the BD sensor 107, and the controller (not shown) exchanges the signal with a scan start signal to
Send to 01. The semiconductor laser 101 starts write modulation after receiving the scanning start signal.

The imaging lens system 104 includes a spherical lens 104
a and the toric lens 104b, and the rotating polygon mirror 1
03 has a so-called fθ function of converting the scanning light L ₀ scanned at a constant angular velocity into the scanning light that scans on the rotating drum 105 in the Y-axis direction at the same running speed.

[0005] A semiconductor laser 101, a cylindrical lens 102c, a rotary polygon mirror 103, an imaging lens system 104,
The BD mirror 106, the BD sensor 107, and the like are attached to the side wall and the bottom wall of the optical box 110 shown in FIG. The rotating drum 105 is provided outside the optical box 110, and a window for extracting the scanning light L ₀ from the optical box 110 toward the rotating drum 105 is provided on a side wall of the optical box 110. The upper opening of the optical box 110 is the lid member 1.
It is closed by 11.

As shown in FIG. 8, a motor for rotating the polygon mirror 103 includes a motor housing supported on a bottom wall of an optical box 110 and a motor board 11 integral with the motor housing.
2, a driving circuit 112a mounted on the
The magnetic circuit is composed of a stator 113 excited by the drive current a and a rotor 114 and the like opposed thereto. The stator 113 has a stator core erected on a motor board 112 and a stator coil wound therearound.
5, and the rotating polygon mirror 103 is
It is pressed against a washer by a pressing spring or the like, and is integrally connected to the rotor 114 via the washer. When the stator 113 is excited as described above, the rotor 114 and the rotating polygon mirror 1 are rotated.
03 rotates together.

In recent years, it has been required to rotate the rotary polygon mirror 103 at a higher speed in order to increase the writing speed. However, when the rotary polygon mirror 103 is rotated at a high speed, the lid member 111 may be warped. Optical box 110
A large amount of outside air is sucked into the optical box 110 from a gap formed between the upper end of the side wall and the lid member 111, dust in the outside air adheres to the reflection surface of the rotary polygon mirror 103, and the reflectance decreases. In order to prevent this, a cylindrical mirror cover 111a is provided inside the lid member 111, and the mirror cover 11a is provided.
1a is designed so as to cover around the rotary polygon mirror 103.

[0008]

However, according to the above prior art, even if a mirror cover for covering the rotary polygon mirror is provided inside the lid member, the mirror cover is removed from the gap left between the mirror cover and the motor substrate. There is an unsolved problem that contamination of the rotating polygon mirror cannot be sufficiently prevented because outside air is sucked into the inside of the mirror.

For example, when both the optical box and the lid member are formed of plastic or the like, a gap of about 0.3 mm cannot be avoided between the optical box and the lid member. Outside air is sucked into the optical box. Part of the outside air that has thus entered the optical box further flows into the inside of the mirror cover and contaminates the rotating polygon mirror.

Recently, the motor of the rotary polygon mirror has tended to be further miniaturized. However, as the miniaturization progressed, screws for fixing the motor substrate, circuit components mounted on the motor substrate, and the like became mirrors. It is often arranged at a position where it interferes with the cover. Therefore, a notch 111b as shown in FIG. 8 is required in the mirror cover, and therefore, the dust-proof effect of the mirror cover is further reduced, and it becomes difficult to prevent contamination of the rotating polygon mirror.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and an object of the present invention is to prevent contamination of a rotating polygon mirror by a rib-like member provided on a lid member of an optical box. It is an object of the present invention to provide a high-performance optical deflection scanning device that can perform the above.

[0012]

In order to achieve the above object, an optical deflection scanning apparatus according to the present invention comprises a rotary polygon mirror for deflecting and scanning a light beam, a motor for rotating the rotary polygon mirror, and a drive circuit therefor. Driving means having a motor board to be mounted;
An optical box accommodating the rotary polygon mirror together with the driving means, and a lid member for closing an opening thereof, the lid member including a rib-shaped member surrounding the rotary polygon mirror and the entire driving means. It is characterized by the following.

[0013] It is preferable that the rib-like member has an elastic body which comes into contact with the bottom surface of the optical box or the outer peripheral portion of the motor substrate.

The lid member may include a second rib member surrounding only the rotating polygon mirror inside the rib member.

[0015] The motor substrate may have a disk shape disposed coaxially with the rotary polygon mirror.

[0016]

By covering the entire driving section including the rotary polygon mirror and the motor substrate with the rib-shaped member provided inside the lid member, contamination of the rotary polygon mirror by dust and the like in the outside air is prevented. It does not require a notch or the like to avoid interference with the circuit components of the motor board, unlike a mirror cover that covers only the rotating polygon mirror, so the atmosphere around the rotating polygon mirror is completely shut off from the outside air and dust is prevented. The effect can be enhanced.

By effectively avoiding contamination of the rotary polygon mirror, it is possible to realize an optical deflection scanning device which has extremely high performance and is maintenance-free for a long time.

If the rib-like member has an elastic body which comes into contact with the bottom surface of the optical box or the outer peripheral portion of the motor board, the dust-proof effect can be further enhanced.

If the lid member has a second rib-like member surrounding only the rotating polygon mirror inside the rib-like member,
An additional advantage is that heat loss of the motor can be reduced by reducing windage of the rotating polygon mirror.

If the motor substrate has a disk shape disposed coaxially with the rotary polygon mirror, the rib-shaped member can be easily processed by making the cross-section of the rib-shaped member circular.
In addition, there is an added advantage that both dust prevention of the rotary polygon mirror and prevention of heat generation of the motor can be expected.

[0021]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an optical deflection scanning device according to a first embodiment. A laser beam L _1, which is a light beam emitted from a semiconductor laser _1, is collimated by a collimator lens _{1 a and} is linearly formed by a cylindrical lens 2. And is incident on the reflecting surface of the rotary polygon mirror 3. The reflected light is deflected and scanned by the rotation of the rotary polygon mirror 3, and
The light becomes scanning light in the Y-axis direction (main scanning direction), and forms an image on a photosensitive member on a rotating drum (not shown) via the imaging lens system 4 and the folding mirror 5. The light beam that forms an image on the photoreceptor forms an electrostatic latent image with the main scanning in the Y-axis direction by the rotation of the rotary polygon mirror 3 and the sub-scanning in the Z-axis direction by the rotation of the rotating drum.

A corona discharger for uniformly charging the surface of the photoreceptor is provided around the photoreceptor, and a visualization device for visualizing an electrostatic latent image formed on the surface of the photoreceptor into a toner image. A transfer corona discharger or the like for transferring the toner image to a recording medium such as a recording paper is disposed, and by these operations, recording information corresponding to the luminous flux generated by the semiconductor laser 1 is printed on the recording paper or the like. You.

The scanning light of the rotary polygon mirror 3 reaches one end of the scanning surface, is reflected by a BD mirror (not shown), is introduced into a BD sensor through a condenser lens, and is converted into a scanning start signal by a controller. Semiconductor laser 1
Sent to. After receiving the scanning start signal, the semiconductor laser 1 starts writing modulation based on image information transmitted from a host computer (not shown).

Semiconductor laser 1, cylindrical lens 2, rotary polygon mirror 3, imaging lens system 4, BD mirror, BD
The sensor and the like are attached to a side wall or a bottom wall of the optical box 6 made of synthetic resin which is integral with the main body frame of the light deflection scanning device.
The rotating drum is disposed outside the optical box 6, and a window is provided on the bottom wall of the optical box 6 for extracting scanning light from the optical box 6 toward the rotating drum. Optical box 6
2 is closed by a lid member 10 shown in FIG. 2, and the lid member 10 is screwed to the optical box 6 at a peripheral edge thereof.

The imaging lens system 4 is composed of a spherical lens 4a and a toric lens 4b, and scans a scanning beam scanned at a constant angular velocity by the rotating polygon mirror 3 on the rotating drum at a constant scanning speed in the Y-axis direction. So-called fθ function.

The positioning of the optical box 6 in the X-axis direction with respect to the main body frame of the light deflection scanning device and the rotation angle θ are determined by positioning pins 7a engaged with guide holes 6a and 6b provided in the support portion on the outside. 7b. Positioning in the X-axis direction is performed by moving both positioning pins 7a and 7b in the same direction in the X-axis direction with respect to the guide holes 6a and 6b, and the rotation angle θ (position in the θ-axis direction)
Is adjusted by the difference in the amount of movement between the two positioning pins 7a and 7b. After adjusting the relative position with respect to the photoconductor in this way, the optical box 6 is fixed to the main body frame by the screws 8a and 8b.

As shown in FIG. 3, a motor 3a for rotatingly driving the rotary polygon mirror 3 includes a motor housing 11 supported on the bottom wall of the optical box 6 and a motor board 12 which constitutes a driving means together with the motor 3a. It is composed of a mounted driving circuit (not shown), a magnetic circuit including a stator 13 excited by a driving current of the driving circuit, a rotor 14 opposed thereto, and the like. The stator 13 has a stator core erected on the motor board 12 and a stator coil wound therearound. The rotor 14 is fixed to a washer 16 integral with the rotating shaft 15. The rotary polygon mirror 3 is pressed against the washer 16 by an elastic pressing mechanism having a holding spring 17 and the like, and is integrally connected to the rotor 14 via the washer 16. When the stator 13 is excited as described above, the washer 16 and the rotary polygon mirror 3 rotate together with the rotor 14.

When both the optical box 6 and the lid member 10 are molded products, the optical box 6 and the lid member 10 cannot be sufficiently sealed due to warpage of the lid member 10 or the like, and the two members cannot be sealed. As shown by the arrow A, outside air enters through the gap, and the dust adheres to the reflecting surface of the rotary polygon mirror 3 to lower the reflectance. In order to prevent this, a cover rib 10a which is a rib-like member is integrally provided inside the lid member 10.

The cover rib 10a of the lid member 10 is disposed so as to surround the entire motor substrate 12, and the lower end of the cover rib 10a is located below the motor substrate 12. As described above, the whole of the rotating polygon mirror 3, the stator 13, the rotor 14, and the motor substrate 12 constituting the motor 3 a are completely covered by the cover rib 10 a of the lid member 10, so that the mirror enters the space between the optical box 6 and the lid member 10. Shut off the outside air,
The contamination of the rotating polygon mirror 3 is prevented.

Since the cover rib 10a is configured to surround the entire motor board 12, there is no possibility that the cover rib 10a will interfere with the circuit components and the screws for fixing the motor board 12.
Therefore, the dust prevention effect of the cover rib 10a can be greatly improved without requiring a notch or the like as in the conventional example.

Since the motor substrate 12 of this embodiment has a rectangular shape, the cover rib 10a of the lid member 10 has a rectangular frame shape, and one side surface thereof has a laser beam which enters and exits the reflection surface of the rotary polygon mirror 3. A window 10b for light is provided.

According to this embodiment, the reflection surface of the rotary polygon mirror is effectively prevented from being contaminated by the outside air entering the optical box, and has high optical performance and is maintenance-free for a long time. An extremely high performance optical deflection scanning device can be realized.

FIG. 4 shows a modification. This is because an elastomer 20b, which is an elastic body, is integrally formed at the tip of the cover rib 20a of the lid member 20 and when the lid member 20 is put on the optical box 6, the elastomer 20b is placed on the bottom surface of the optical box 6.
b is elastically contacted, and a gap B between the cover rib 20a and the cover rib 20a is sealed by the elastomer 20b.

The cover rib 20 is formed by the elastomer 20b.
a can further enhance the dustproof effect. In addition, instead of abutting the elastomer 20b on the bottom surface of the optical box 6,
The outer peripheral portion of the motor substrate 12 may be contacted.

FIG. 5 shows still another modification. this is,
The cover member 30 is provided with a cylindrical cover rib 30a that covers the outside of the disk-shaped motor substrate using a disk-shaped motor substrate disposed coaxially with the rotary polygon mirror 3. Since the shape of the cover rib 30a is simple, molding of the lid member 30 is easy, and therefore, the processing cost is low. Further, by bringing the cover rib 30a close to the rotary polygon mirror 3, windage loss can be reduced, energy loss such as heat generation of the motor can be reduced, and even if the rotational position of the motor substrate is shifted with respect to the optical box 6. Since the cover rib 30a can be brought close to the motor substrate, an advantage that the dustproof effect is high is also added.

FIG. 6 shows a second embodiment, in which, similarly to the first embodiment, a cover member 40a having a rectangular frame shape is provided on a lid member 40, and thereby a motor substrate 42 is provided.
(See FIG. 7) and cover ribs 40a.
, A mirror cover 40b, which is a second rib-shaped member, is provided near the reflecting surface of the rotary polygon mirror 3.

The semiconductor laser 1, the rotary polygon mirror 3, the imaging lens system 4 and the like are the same as those in the first embodiment, so they are denoted by the same reference numerals, and description thereof will be omitted.

A cover rib 40 integral with the lid member 40
a and the mirror cover 40b doubly cover the rotary polygon mirror 3 to further enhance the dust-proofing effect, and further reduce the windage of the rotary polygon mirror 3 to prevent the motor from generating heat. You.

[0040]

Since the present invention is configured as described above, it has the following effects.

The rib-shaped member provided on the lid member of the optical box can extremely effectively prevent contamination of the rotary polygon mirror, and can realize an optical deflection scanning device which is high-performance and maintenance-free for a long time. By mounting such a light deflection scanning device, it is possible to greatly contribute to improving the performance of the image forming apparatus and reducing the running cost.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a light deflection scanning apparatus according to a first embodiment with a lid member removed.

FIG. 2 is a partially broken schematic plan view showing the apparatus of FIG. 1 with a lid member attached, with a part of the lid member broken away.

FIG. 3 is a schematic partial sectional view showing a main part of the device of FIG. 2;

FIG. 4 is a schematic partial sectional view showing a first modification of the first embodiment.

FIG. 5 is a partially broken schematic plan view showing a second modified example of the first embodiment, with a part thereof broken away.

FIG. 6 is a partially broken schematic plan view showing a light deflection scanning device according to a second embodiment, with a part thereof broken away.

FIG. 7 is a schematic partial sectional view showing a main part of the device of FIG. 6;

FIG. 8 is a schematic partial cross-sectional view showing a main part of one conventional example.

FIG. 9 is a diagram illustrating the entire device of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 3 Rotating polygon mirror 4 Imaging lens system 6 Optical box 10, 20, 30, 40 Lid member 10a, 20a, 30a, 40a Cover rib 20b Elastomer 12, 42 Motor substrate 40b Mirror cover

Claims (4)

[Claims] A rotary polygon mirror for deflecting and scanning a light beam;
A drive unit having a motor for rotating the rotary polygon mirror and a motor board on which a drive circuit is mounted, an optical box accommodating the rotary polygon mirror together with the drive unit, and a lid member for closing an opening thereof; An optical deflection scanning device, wherein a lid member includes a rib-shaped member that surrounds the rotary polygon mirror and the entire driving means. 2. The optical deflection scanning device according to claim 1, wherein the rib-shaped member includes an elastic body that is in contact with a bottom surface of the optical box or an outer peripheral portion of the motor substrate. 3. The optical deflection scanning device according to claim 1, wherein the lid member includes a second rib member surrounding only the rotary polygon mirror inside the rib member. 4. The optical deflection scanning device according to claim 1, wherein the motor substrate has a disk shape disposed coaxially with the rotary polygon mirror.