JPH06300983A - Light deflector - Google Patents

Abstract

(57) [Abstract] [Purpose] In an optical deflector, the temperature rise inside the optical box is easily suppressed. [Structure] The optical box 21 includes a polygon mirror 27, a motor substrate 29, a motor 22 including a driving IC 30, and the like.
The optical box 21 is covered with a cover 31. The cover 31 has a concave portion 3 on the upper portion of the polygon mirror 27.
1b is formed, a vent 31d is formed in the horizontal portion 31c, and a filter 32 is fixed to the vent 31d. On the other hand, the bottom wall 21a of the optical box 21 has an exhaust port 21b.
Is provided. When the polygon mirror 27 rotates, the outside air permeates the filter 32 and flows into the inside, and the inside air is discharged from the exhaust port 21b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector used in a laser beam printer or the like.

[0002]

2. Description of the Related Art A conventional optical deflector of this type is constructed as shown in the plan view of FIG. 7 and the sectional view of FIG. That is, the laser beam L emitted from the laser generator 1 is reflected by the polygon mirror 2, passes through the imaging lens group 3, and then forms an image on the photosensitive drum 4. At this time, the polygon mirror 2 is rotated by the motor 5, part of the laser beam L is guided to the detector 7 by the reflection mirror 6, and the writing timing for each scanning of the laser beam L is detected.

The motor 5 comprises a rotor 8, a rotary shaft 9, a motor board 10, a housing 11 and the like.
A driving IC 12 is arranged on the 0. The polygon mirror 2 is fixed to the rotor 8 by a pressing spring 13.

Such a motor 5 is housed in an optical box 14, and a cover 15 is fixed to the optical box 14 by a claw 15a so that dust and the like outside the optical box 14 do not enter inside.

[0005]

However, in the above-mentioned conventional example, when the motor 5 is operated, the driving IC 12 and the bearing (not shown) generate heat and the temperature inside the optical box 14 rises.
The degree of this temperature rise is influenced by the number of revolutions of the motor 5 and the ambient temperature, and when the degree of temperature rise is large, the driving IC 12
May malfunction, the life of the bearing may be shortened, or the mirror surface 2a of the polygon mirror 2 may be distorted.

On the other hand, in order to suppress the temperature rise in the inside, it is sufficient to supply the outside air to the inside and discharge the inside air to the outside, but in this case, dust or the like enters the inside and the polygon There is a risk that the mirror 2 and other optical systems will be contaminated. In order to solve such a problem, a filter may be provided in the air flow path, but in order to secure an air flow rate, a fan or the like must be provided separately, which complicates and enlarges the device, There is a problem that the cost will increase significantly.

An object of the present invention is to solve the above-mentioned problems and to provide an optical deflector capable of easily suppressing the temperature rise inside the optical box.

[0008]

An optical deflector according to the present invention comprises a motor that rotates a polygon mirror, an optical box that houses the motor, and a cover that covers the optical box.
A vent is provided in the cover near the center of rotation of the polygon mirror, and a filter is provided in the vent.

[0009]

In the optical deflector having the above-described structure, by providing the ventilation hole in the cover near the center of rotation of the polygon mirror, when the polygon mirror rotates, the air outside the optical box flows into the inside.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a sectional view of the first embodiment, in which a motor 22 is housed in an optical box 21 and a motor 23
The housing 23 is fitted in a hole provided in the bottom wall 21 a of the optical box 21. The housing 23 has a rotary shaft 24.
Is rotatably fitted through a bearing (not shown), the rotor 25 is fixed to the rotary shaft 24, and the flange 2 is mounted on the rotor 25.
The polygon mirror 27 is placed via the rotary shaft 24.
It is pressed and fixed by a presser spring 28 fixed to.
A motor board 29 is fixed to the upper portion of the flange portion 23a of the housing 23, and a driving IC 30 for controlling the rotation of the motor 22 is mounted on the motor board 29.

A cover 31 is fixed by a claw 31a to the optical box 21 containing the motor 22 as described above. A recess 31b is formed in the cover 31 on the rotation center of the polygon mirror 27, and a vent 31d is formed in the horizontal portion 31c of the recess 31b close to the rotation center of the polygon mirror 27.
Is provided. Further, a filter 32 is provided in this ventilation port 31d. On the other hand, the bottom wall 21 of the optical box 21
The a is provided with one or a plurality of exhaust ports 21b.

Normally, as shown in FIG.
When it is rotated by
The air above and below the air flows in toward the disc 33 and flows out along the upper and lower surfaces of the disc 33 toward the outer peripheral edge.

Therefore, when the polygon mirror 27 rotates as shown in FIG. 1, the air above the polygon mirror 27 flows from the outside of the optical box 21 toward the surface of the polygon mirror 27 by its pumping action, and then the polygon mirror 27 rotates. It flows out in the outer peripheral direction along the surface of the mirror 27. At the same time, the internal air is discharged to the outside through the exhaust port 21b.

As described above, when the polygon mirror 27 rotates, the outside air passes through the filter 32 and is guided inside, so that the driving IC 30, the polygon mirror 27, a bearing portion (not shown), etc. are cooled and the driving IC 30 is cooled. Malfunctions, shortening of the life of the bearing, and distortion of the mirror surface 27a of the polygon mirror 27 are prevented.

When the optical deflector is provided with an opening for a scanning beam or the like, the exhaust port 21 as in this embodiment is used.
It is not necessary to provide b. In addition, the motor 2 is installed in the optical box 21.
Although the case where 2 and the polygon mirror 27 are housed has been described, the present embodiment can be applied to the case where other optical systems are housed. Further, this embodiment can be applied even when the motor board 29 is separated.

3 and 4 show a second embodiment, FIG. 3 is a perspective view of a filter, and FIG. 4 is a partially enlarged sectional view of a cover. The filter unit 41 includes a frame 42 and a filter 4.
3, the frame 42 is formed in a circular shape with a plastic material or the like, and the filter 43 is fixed thereto with an adhesive or the like. On the other hand, the recess 44a of the cover 44
An annular vertical portion 44b and a horizontal portion 44c are formed on the bottom side of, and a circular vent 44d is formed in the horizontal portion 44c. Further, the vertical portion 44b is provided with claw portions 44e at several places.

With such a configuration, the filter unit 41 is provided from the outside along the inner circumference of the vertical portion 44b to the horizontal portion 4a.
4c is pushed in and locked by the claw portion 44e. In this embodiment, since the filter 43 can be attached and detached as the filter unit 41, the workability of replacing the filter 43 is improved.

FIG. 5 is a perspective view of the third embodiment of the optical box viewed from the bottom, and FIG. 6 is a partially enlarged sectional view thereof. Optical box 5
An exhaust port 51b is formed in the bottom wall 51a of
A flexible seat valve 52 is fixed to the outside of the optical box 51 so as to cover 1b. One edge of the seat valve 52 is fixed to the optical box 51 with an adhesive 53, and the other edge of the seat valve 52 is easily bent outward.

With such a configuration, when the polygon mirror is stationary, the seat valve 52 closes the exhaust port 51b as shown in FIG. 6A, but the polygon mirror rotates and the optical box 51 rotates. When air flows into the inside of the
As shown in (b), the seat valve 52 is bent outward by the internal air pressure, and the internal air is discharged to the outside as shown by the arrow.

In this embodiment, since the exhaust port 51b is closed by the seat valve 52 when the polygon mirror is stationary, external dust or the like does not enter the inside through the exhaust port 51b. .

[0021]

As described above, in the optical deflector according to the present invention, the cover near the center of rotation of the polygon mirror is provided with the vent hole, and the vent hole is provided with the filter. As a result, the air outside the optical box flows into the optical box, and the temperature rise inside is suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is an explanatory diagram of a pump action.

FIG. 3 is a perspective view of a filter unit according to a second embodiment.

FIG. 4 is a cross-sectional view of a filter unit mounting portion of a cover.

FIG. 5 is a perspective view of a third embodiment.

FIG. 6 is a partially enlarged sectional view.

FIG. 7 is a perspective view of a conventional example.

FIG. 8 is a sectional view of a conventional example.

[Explanation of symbols]

 21, 51 Optical box 21b, 51b Exhaust port 22 Motor 27 Polygon mirror 31, 44 Cover 32, 43 Filter 41 Filter unit 52 Seat valve

Claims (3)

[Claims] 1. A motor for rotating a polygon mirror, an optical box for accommodating the motor, and a cover for covering the optical box. A vent is provided in the cover near the rotation center of the polygon mirror, and the ventilation is provided. An optical deflector having a filter provided at its mouth. 2. The optical deflector according to claim 1, wherein the vent has a means for attaching and detaching the filter. 3. The optical deflector according to claim 1, wherein an exhaust port is provided in the optical box.