JP3192271B2 - Optical deflector - Google Patents

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 for 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 a plan view of FIG. 7 and a sectional view of FIG. That is, the laser beam L emitted from the laser generator 1 is reflected by the polygon mirror 2 and forms an image on the photosensitive drum 4 after passing through the imaging lens group 3. At this time, the polygon mirror 2 is rotated by the motor 5, a part of the laser beam L is guided to the detector 7 by the reflection mirror 6, and the writing start timing of the laser beam L for each scan is detected.

The motor 5 includes a rotor 8, a rotating shaft 9, a motor board 10, a housing 11, and the like.
The driving IC 12 is disposed on the reference numeral 0. The polygon mirror 2 is fixed to the rotor 8 by a holding spring 13.

[0004] Such a motor 5 is accommodated in an optical box 14, and a cover 15 is fixed to the optical box 14 by claws 15 a so that dust and the like outside the optical box 14 do not enter the inside.

[0005]

However, in the above-described conventional example, when the motor 5 is operated, the driving IC 12 and a bearing (not shown) generate heat and the inside of the optical box 14 is heated.
The degree of the temperature rise is affected by the rotation speed of the motor 5 and the ambient temperature.
May malfunction, the life of the bearing may be reduced, or the mirror surface 2a of the polygon mirror 2 may be distorted.

On the other hand, in order to suppress the internal temperature rise, it is sufficient to supply external air to the inside and discharge the internal air to the outside. There is a possibility that the mirror 2 and other optical systems are soiled. In order to solve such a problem, a filter may be provided in the air flow path, but in order to secure the air flow rate, a fan or the like must be separately provided, and the device becomes complicated and large, The problem that cost rises sharply arises.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical deflector which solves the above-mentioned problems, suppresses the temperature rise inside the optical box during operation, and prevents intrusion of dust when the optical box is stopped.

[0008]

According to the present invention, there is provided an optical deflector for accommodating a polygon mirror which is rotated by a motor and having an air outlet provided with an exhaust port and a filter. A flexible seat valve that closes the exhaust port during rotation stop of the polygon mirror and opens the exhaust port by being bent by air pressure in the optical box during rotation is attached to the exhaust port. Features.

[0009]

In the optical deflector having the above structure, when the polygon mirror rotates, air flows into the optical box from the outside and exhausts from the exhaust port, and the exhaust port is closed while the rotation of the polygon mirror is stopped.

[0010]

FIG. 1 is a sectional view of a reference example, in which an optical box 21 accommodates a motor 22 and a housing 23 of the motor 23.
Are fitted into holes provided in the bottom wall 21 a of the optical box 21. A rotating shaft 24 is rotatably fitted to the housing 23 via a bearing (not shown).
5, a polygon mirror 27 is mounted on it via a flange 26, and is pressed and fixed by a pressing spring 28 fixed to the rotating shaft 24. A motor board 29 is fixed above the flange 23 a of the housing 23, and a drive IC 30 for controlling the rotation of the motor 22 is mounted on the motor board 29.

A cover 31 is fixed to the optical box 21 in which such a motor 22 is housed by claws 31a. The cover 31 has a concave portion 31b formed on the rotation center of the polygon mirror 27, and the horizontal portion 31c of the concave portion 31b has a ventilation opening 31d close to the rotation center of the polygon mirror 27.
Is provided. Further, a filter 32 is provided in the vent 31d. On the other hand, the bottom wall 21 of the optical box 21
a is provided with one or a plurality of exhaust ports 21b.

Normally, as shown in FIG.
Is rotated by the pump action,
Above and below flow into the disk 33 and flow out toward the outer peripheral edge along the upper and lower surfaces of the disk 33.

Accordingly, 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 the pump action, and then the polygon is rotated. It flows out in the outer peripheral direction along the surface of the mirror 27. At the same time, the internal air is exhausted 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, the bearing (not shown) and the like are cooled, and the driving IC 30 Malfunction, reduction in the life of the bearing, distortion of the mirror surface 27a of the polygon mirror 27, and the like are prevented.

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

With such a configuration, the filter unit 41 is externally provided along the inner periphery of the vertical portion 44b.
4c and is locked by the claw 44e. In the present embodiment, since the filter 43 is detachable as the filter unit 41, the workability of replacing the filter 43 is improved.

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

With such a configuration, when the polygon mirror is stationary, the seat valve 52 blocks the exhaust port 51b as shown in FIG. When air flows into the interior of FIG.
As shown in (b), the seat valve 52 bends outward due to the internal air pressure, and the internal air is discharged to the outside as indicated by the arrow.

In this embodiment, when the polygon mirror is stationary, the exhaust port 51b is closed by the seat valve 52, so that external dust and the like do not enter the interior through the exhaust port 51b. .

[0020]

As described above, in the optical deflector according to the present invention, when the polygon mirror rotates, the air outside the optical box flows into the optical box by the pumping action, and the temperature rise inside the optical box is suppressed. The air is discharged through the discharge port, but when the rotation of the polygon mirror stops, the seat valve closes the discharge port, so that air from outside does not enter.

[Brief description of the drawings]

FIG. 1 is a sectional view of a reference example.

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

FIG. 3 is a perspective view of the filter unit of the embodiment.

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

FIG. 5 is a perspective view of an exhaust port of the 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 (1)

(57) [Claims] 1. A polygon mirror rotated by a motor.
It is housed and equipped with an exhaust port and an air inlet with a filter.
Optical box, and while the rotation of the polygon mirror is stopped
While the exhaust port is closed and rotating, the air pressure in the optical box is
The flexible seat valve that bends to open the exhaust port
An optical deflector characterized by being attached to the mouth .