JP3402967B2 - Scanning optical 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 scanning optical device used in an image forming apparatus such as a laser beam printer.

[0002]

2. Description of the Related Art In a conventional scanning optical device of this type, for example, as shown in FIG. 6, a semiconductor laser light source 2 is provided in an optical frame 1, and a laser beam emitted from the light source 2 has a cylindrical direction. The lens 3 and the rotary polygon mirror 4 are sequentially arranged. The rotary polygon mirror 4 is rotationally driven by a drive motor 5, and the laser light is deflected at high speed by the rotary polygon mirror 4. Imaging lenses 6 and 7 and a reflection mirror 8 are sequentially arranged in the traveling direction of the deflected laser light, and these imaging lenses 6 and 7 are fθ.
It is used as a lens. The photosensitive drum 9 is arranged in the reflection direction of the reflection mirror 8, and the opening of the optical frame 1 is closed by a cover 10.

[0003]

In recent years, as the demand for high-speed and high-definition scanning optical devices of this type increases, the rotary polygon mirror 4 is driven to rotate at a higher speed. Therefore, the conventional example has the following problems.

(1) Since the amount of dust adhering to the rotary polygon mirror 4 increases, the reflectance of the rotary polygon mirror 4 decreases.
Therefore, the amount of light incident on the photosensitive drum 9 is reduced, and a desired image cannot be formed.

(2) As the vibration of the drive motor 5 increases, the vibration of the optical frame 1 and the cover 10 also increases, and the noise also increases.

(3) In order to suppress an increase in vibration and noise, an elastic member such as foamed polyurethane may be provided between the optical frame 1 and the cover 10, but workability is required for attaching the elastic member. And the manufacturing cost is high.

(4) When the elastic member is provided, the elastic member may deform the optical frame 1. Particularly, when the vicinity of the reflection mirror 8 is deformed, the irradiation position of the laser light is changed and the performance is deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a scanning optical device which solves the above-mentioned problems, improves the workability of attaching a cover, and prevents dust intrusion, vibration, noise and optical frame deformation. It is in.

[0009]

A scanning optical device according to the present invention for achieving the above object comprises a light source for emitting a light beam, a deflecting means for deflecting the light beam from the light source, and a deflecting means. An image forming lens for forming an image of the light beam on the image carrier, and a reflection mirror for reflecting the light beam from the image forming lens toward the image carrier are arranged in the optical frame,
In a scanning optical apparatus in which a cover is covered with an elastic member for sealing in the optical frame, the elastic member is integrally provided on the cover, and at least one of thickness and hardness of the elastic member is partially different. Thus, the deformation of the optical frame is prevented.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail with reference to the embodiments shown in FIGS. 1 is a plan view of the first embodiment with a cover removed, and FIG. 2 is a cross-sectional view with a cover attached. The box-shaped optical frame 11 has a semiconductor laser or the like inside and an image. A light source 12 that blinks based on information is attached. In the traveling direction of the laser light from the light source 12, a cylindrical lens 13 having a curvature in only one direction and a rotary polygon mirror 14 for deflecting the laser light from the cylindrical lens 13 are sequentially arranged. The laser light is linearly focused on the mirror surface 14a of the rotary polygon mirror 14. The rotary polygon mirror 14 is supported by a drive motor 15 and is rotationally driven at high speed.

Imaging lenses 16 and 17 and a reflecting mirror 18 are sequentially arranged in the traveling direction of the laser beam deflected by the rotary polygon mirror 14, and a photosensitive drum 19 is arranged in the reflecting direction of the reflecting mirror 18. ing. Imaging lens 16,
Reference numeral 17 denotes an fθ lens, which forms a laser beam deflected at a constant angular velocity by the rotary polygon mirror 14 on the photosensitive drum 19 in a desired shape and scans at a constant velocity. The fixed mirror 20 is arranged in the traveling direction of the laser light in the non-image area deflected by the rotary polygon mirror 14 in order to take the horizontal cycle of the image, and the fixed mirror 20 reflects the laser light in the reflecting direction. A sensor 21 for detecting the is provided.

On the bottom wall of the optical frame 11, there is provided a window 11a for passing the laser light from the reflection mirror 18 to the outside of the optical frame 11, and this window 11 is provided.
A is blocked by the glass 22 to prevent dust floating in the air from entering the optical frame 11 through the window 11a. Further, a cover member 23 for covering the upper opening of the optical frame 11 is covered on the upper portion of the optical frame 11. Therefore, the optical frame 11 is provided with a stepped portion 11b for accommodating the cover member 23, and the stepped portion 11b is provided with a recessed portion 11c behind the reflection mirror 18.

As shown in FIG. 3, the cover member 23 fits in the cover main body 24 having a shape in which the peripheral wall of the stepped portion 11b of the optical frame 11 is accommodated with a slight gap, and the stepped portion 11b excluding the concave portion 11c. The first elastic member 25 provided on the peripheral edge of the cover body 24, and the second elastic member 26 provided on the peripheral edge of the cover body 24 so as to fit into the concave portion 11c having the downward protruding portion 26a. It is configured.
These elastic members 25 and 26 are made of, for example, foamed polyurethane, rubber or the like, and are integrally formed so as to surround the periphery of the cover body 24 as shown in FIG. The first elastic member 25 has a hardness or a thickness that can sufficiently seal the periphery of the cover body 24 when compressed. The hardness of the second elastic member 26 is smaller than that of the first elastic member 25, and the protrusion 26a has a thickness that is slightly compressed in the recess 11c.

When the cover member 23 is attached to the optical frame 11, the projecting portion 26a of the second elastic member 26 is fitted into the recessed portion 11c of the optical frame 11.
The cover member 23 is arranged on the step portion 11b of the optical frame 11, and the cover member 23 is fixed to the optical frame 11 by a fixing means (not shown). At this time, the first elastic member 25
Seals the periphery in a compressed state, and the protrusion 26a seals the periphery in a slightly compressed state in the recess 11c.

As described above, in the embodiment, since the first elastic member 25 and the second elastic member 26 are integrally provided on the peripheral edge of the cover body 24, the workability of assembling the cover member 23 can be improved. At the same time, the periphery of the cover body 24 can be sealed, and noise due to dust intrusion, vibration, chattering, etc. can be prevented. Further, the hardness of the second elastic member 26 is made smaller than that of the first elastic member 26, and the protrusion 26
Since a is provided, the amount of compression of the protruding portion 26a can be reduced, and the force applied to the optical frame 11 can be reduced. As a result, it is possible to prevent the reflection mirror 18 from changing and prevent the performance from deteriorating.

It is preferable that the rubber used for the elastic members 25 and 26 is treated so that the vulcanizing agent and the plasticizer do not exude. Further, although the elastic members 25 and 26 have different hardness and thickness, the optical frame 1
If 1 is not deformed, at least one of hardness and thickness may be different. Further, although the elastic members 25 and 26 are separate members, they may be integrated and the protrusion 26a of the second elastic member 26 may be attached to the first elastic member 25.

FIG. 5 is a sectional view of the second embodiment, in which the optical frame 31 is provided with the window 31a and the step portion 31b similar to those of the first embodiment, and above the reflection mirror 18. A step portion 31c lower than the step portion 31b is formed. The cover member 32 is composed of a cover body 24 similar to that of the first embodiment and a third elastic member 33 integrally provided on the peripheral edge of the cover body 24. Further, a fourth elastic member 34 for sealing between the imaging lens 16 and the cover member 32 is arranged above the imaging lens 16. These elastic members 33, 34 are
The material is the same as that of the elastic members 25 and 26 of the embodiment.

When the cover member 32 is attached to the optical frame 31, the third elastic member 33 is slightly compressed at the step 31c, but is strongly compressed at the step 31b side than at the step 31c side. Fourth elastic member 34
Is also compressed so that the surroundings are sealed.

In the second embodiment, since the amount of compression on the side of the step 31c is smaller than that on the side of the step 31b, the deformation of the optical frame 31 can be prevented as in the first embodiment.
At this time, the degree of sealing of the stepped portion 31c is inferior to that of the stepped portion 31b side, but the fourth compression member 34 can prevent dust from entering the rotary polygon mirror 14, which is the same as the first embodiment. Similar effects can be obtained.

[0020]

As described above, in the scanning optical device according to the present invention, since the elastic member is integrally provided on the cover, the workability of attaching the cover is improved, and the invasion of dust, vibration and noise are prevented. You can Further, since at least one of the thickness and the hardness of the elastic member is made partially different to prevent the optical frame from being deformed, it is possible to prevent the irradiation position of the light beam from varying and prevent the performance from deteriorating.

[Brief description of drawings]

FIG. 1 is a plan view of the first embodiment with a cover removed.

FIG. 2 is a cross-sectional view with a cover attached.

FIG. 3 is a perspective view of a cover member.

FIG. 4 is a partially enlarged view.

FIG. 5 is a cross-sectional view of the second embodiment.

FIG. 6 is a configuration diagram of a conventional example.

[Explanation of symbols]

11,31 Optical frame 12 light sources 14 rotating polygon mirror 16, 17 Imaging lens 18 reflective mirror 23, 32 cover member 25, 26, 33, 34 Elastic member

Claims (4)

(57) [Claims] 1. A light source for emitting a light beam, a deflection means for deflecting the light beam from the light source, an imaging lens for forming an image of the light beam from the deflection means on an image carrier, and the imaging In a scanning optical device in which a reflection mirror that reflects a light beam from a lens toward the image carrier is disposed in an optical frame, and a cover is covered with an elastic member for sealing interposed in the optical frame, A scanning optical device, wherein the elastic member is provided integrally with the cover, and at least one of thickness and hardness of the elastic member is partially different to prevent deformation of the optical frame. 2. The scanning optical device according to claim 1, wherein at least one of the thickness and the hardness of the elastic member is different between the vicinity of the deflecting means and the vicinity of the reflection mirror. 3. The scanning optical device according to claim 1, wherein the elastic member is a different member in the vicinity of the polarizing means and in the vicinity of the reflection mirror. 4. The method according to claim 1, wherein the optical frame is provided with a recess near the reflection mirror, and the elastic member is provided with a protrusion that fits into the recess. A scanning optical device as described.