JPH0335646B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical polarization device that scans laser light by rotating a polygon mirror, for example.

[Technical background of the invention and its problems]

Recently, optical deflection devices have been introduced as a central mechanism in electrophotographic transfer printers (laser printers) that print characters and symbols using laser light. Figure 4 shows a laser printer.
This laser printer has a semiconductor laser device A, a light polarizing device B, and a photosensitive drum C as main components. Thus, the laser light emitted from the semiconductor laser device A is converged by the first optical system D and projected onto the modulator E. Then, in this modulator E, the laser light undergoes optical intensity modulation according to the electrical signal applied to this modulator E. Next, the laser beam modulated by the modulator E is transmitted to the polygon mirror G of the optical polarizer B via the second optical system F.
incident on . At this time, if the polygon mirror G is rotated at a constant speed in the direction of arrow _R1 , the laser beam will be transmitted through the polygon mirror G.
The photosensitive drum C is reflected and deflected by the third optical system H, and is scanned onto the surface of the photosensitive drum C, which is rotating at a constant speed in the direction of arrow _R2 , and a latent image is formed on the scanned surface of the photosensitive drum C. be done.

In this laser printer, in order to print at high speed, it is necessary to rotate the polygon mirror that scans the laser beam at high speed. Therefore, generally, an optical deflection device as shown in FIG. 5 is used to scan the laser beam. That is, in this optical deflection device, a fixed shaft 2 is fixed at both ends thereof by screws 3, 3 so as to be substantially coaxial inside a cylindrical housing 1. A cylindrical rotating body 4 passes through the fixed shaft 2. The rotating body 4 is suspended by a magnetic thrust bearing 5 provided on the outer periphery of the lower end. In addition, at both ends of the fixed shaft 2,
Dynamic pressure generating grooves 6 are carved to form a dynamic pressure gas journal bearing section 7 between the rotating body 4 and support the radial force of the rotating body 4 rotating at high speed in a non-contact manner. It's summery. Furthermore, a motor/rotor 8 is mounted around the outer circumference of the upper end of the rotating body 4, and together with a motor/stator 9 attached to the housing 1, a motor 10 is formed. Rotating body 4 with attached
It is designed to be driven in rotation.

By the way, the optical deflection device with the above structure has a fixed axis 2.
Since both ends of the fixing shaft 2 are fixed, the pair of fitting holes into which the fixed shaft 2 is fitted and the threaded holes into which the screws 3 are threaded need to be coaxial. If they are not coaxial, there is a risk that an excessive force will be applied to the fixed shaft 2, causing the shaft to bend. However, it is extremely difficult to assemble the fitting holes and screw holes at both ends of the fixed shaft 2 so that they are coaxial, and there is a problem that the number of parts and steps increase. Therefore, it is preferable that the fixed shaft 2 has a cantilever structure. However, when transporting the optical deflector, in order to fix the rotating body 4, the rotating body 2 is pressed from the right angle direction by the fixing screw 12, so it is not possible to make the fixed shaft 2 have a cantilevered structure. It's getting difficult.
In other words, if a cantilever structure is adopted, the fixed shaft 2 will be deformed by the pressing force of the fixing screw 12, so it is necessary to support the fixed shaft 2 at both ends.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an optical deflection device that can be assembled easily and accurately, and that can reliably fix a rotating body during transportation. do.

[Summary of the invention]

The fixed shaft has a cantilever structure and is equipped with a rotating body fixing part that presses the rotating body loosely inserted into the fixed shaft toward the fixed end of the fixed shaft and fixes it integrally with the housing. It is.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the optical deflection device of this embodiment. This optical deflection device has a cylindrical housing part 1.
3, and a fixed shaft part 1 whose lower end is fixed almost coaxially to the hollow part 14 of this housing part 13.
5, a rotating body part 16 that surrounds the fixed shaft part 15 with a slight gap, and a magnetic thrust that supports the force in the axial direction of the rotating body part 16 and suspends it in a non-contact manner. Bearing section 17 and rotating body section 1
A dynamic pressure gas journal bearing part 18 that supports the radial force of 6 in a non-contact manner, a rotation drive part 19 that rotates the rotary body part 16 at a speed of, for example, 10,000 revolutions per minute or more, and a timely fixation of the rotary body part 16. It consists of a rotating body fixing part 20. Thus, the housing part 13 includes a lower housing 21, an upper housing 22,
It consists of fastening means (not shown), such as screws, for fastening these pair of housings 21 and 22 together. Further, although not shown, the lower housing 21 is provided with a window portion that serves as a passage for laser light. Furthermore, the fixed shaft portion 15 has a cylindrical fixed shaft 2.
3 and the lower end of the fixed shaft 23
Fixing screw 24 fixing the to the lower housing 21
and a washer 25 interposed between the fixing screw 24 and the lower housing 21.
Additionally, a tapered portion 2 is provided at the lower end of the fixed shaft 23.
6 is formed and adapted to fit into the lower housing 21. And this fixed shaft 23
The center part is a small diameter part 27 whose diameter is smaller than other parts.
It is becoming. On the other hand, the rotating body section 16 includes a cylindrical rotating body 28, a flange 29 protruding from the outer circumference of the rotating body 28, and a rotating body 29 directly below the flange 29.
8 and a polygon mirror 30 coaxially mounted around the mirror 8. Moreover, the magnetic thrust bearing part 17 is
A ring-shaped first magnet part 31 is attached to the lower end of the rotating body 28, and a first magnet part 31 fixed to the inner circumferential surface of the lower housing 21 has a diameter of several hundred μm on one side, for example.
A second magnet part 32 is coaxially surrounded with a gap left.
It is made up of. These first and second magnet parts 31 and 32 each consist of an even number of permanent magnet plates layered in multiple stages, and the rotating body part 1 is placed between them.
6 in a magnetic pole relationship forming a magnetic loop that supports 6 in the axial direction. Further, the hydrodynamic gas journal bearing section 18 is connected to a pair of journals 3 that are large diameter portions at both ends of the fixed shaft 23.
3, 33, and a pair of bushes 34, 34 fitted into the rotating body 28 so as to surround the journals 33, 33 with a gap of several tens of micrometers or less on one side.
It is made up of. Then Journal 33,
Herringbone-shaped dynamic pressure generating grooves 35 are carved on the outer peripheral surface of the groove 33. Furthermore, the rotation drive unit 19
The rotor 36 is coaxially mounted on the upper end of the rotor 36 so as to be placed on the flange 29, and the stator 37 is fixed to the upper housing 22 so as to coaxially surround the rotor 36. . As shown in FIG. 2, the rotating body fixing part 20 is screwed inside the upper housing 22 coaxially with the fixed shaft 23, and is provided with a pressing member such that its lower end abuts against the upper end surface of the rotating body 28. It consists of a body 38 and an annular protrusion seat 39 that protrudes from the inner bottom surface of the lower housing 21 coaxially with the fixed shaft 23 and supports the rotating body 28 pushed down by the pressing body 38. The pressing body 38 is made of plastic, for example, and
It consists of a threaded part 40 that is screwed into the upper housing 22, and a bottomed cylindrical contact part 41 that is coaxially connected to the threaded part 40 and has an open lower end. The outer diameter of this contact portion 41 is set to be approximately equal to the outer diameter of the rotating body 28.

Therefore, when transporting the optical deflection device configured as described above, in order to prevent damage caused by vibration of the rotating body 28, first screw the threaded part 40 of the pressing body 38 and rotate the abutting part 41. After making contact with the upper end surface of the body 28 , the rotating body 28 is further pressed against the magnetic force of the magnetic thrust bearing portion 17 until the lower end surface of the rotating member 28 comes into contact with the protrusion seat 39 . Thus, the rotating body 28 is integrally fixed to the housing part 13 by the rotating body fixing part 20.

As described above, in the optical deflection device of this embodiment, the rotating body part 16 floating by the magnetic thrust bearing part is pressed downward from the upper end part in the axial direction and fixed, so that the rotating shaft 23 can be fixed. It can have a cantilevered structure, and the tapered portion 26 can easily provide a desired perpendicularity. Therefore, assembly becomes easy and the number of man-hours is reduced, so that the efficiency of assembly work is improved.

Note that, as shown in FIG. 2, in the pressing body 38, the threaded portion 40 and the contact portion 41 may not be made into an integral part, and the tip of the threaded portion 40 may be loosely fitted into the contact portion 41. By doing so, damage to the upper end surface of the rotating body 28 can be prevented.

Further, as shown in FIG. 3, the rotating body fixing part 20
a compression spring 42, a contact body 43 suspended from the compression spring 42, and a contact body 4 that is screwed onto the upper housing 22 and only when the rotating body 28 is not fixed.
3 and a screw 44 for pulling up the contact body 43 upward. Further, in the above embodiment, the lower end of the fixed shaft 23 is fixed, but the upper end may be fixed, and the rotating body 28 may be pressed upward in the axial direction by the rotating body fixing part.

〔Effect of the invention〕

In the optical deflection device of the present invention, a cylindrical rotating body part floating by a magnetic thrust bearing part and surrounding a fixed shaft is fixed by being pressed against the inner surface of a housing part along the axial direction by a rotating body fixing part. Therefore, the fixed shaft can have a cantilevered structure.
Therefore, the assembly becomes easy and the number of man-hours is reduced, so that the efficiency of the assembly work is improved. especially,
The rotating body can be rotated without applying external force to the fixed shaft.
Since it is pressed directly against the inner end surface of the housing part through the cylindrical contact part, deformation and damage to the fixed shaft can be prevented, and damage caused by positional errors such as tilting of the fixed shaft can be prevented. It is possible to prevent a decrease in the rotation accuracy of the rotating body portion.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional front view of an optical deflection device according to an embodiment of the present invention, FIGS. 2 and 3 are main part sectional views of a rotating body fixing part of another embodiment of the present invention, and FIG. 4 is a laser beam deflection device. FIG. 5, an explanatory diagram of the printer, is a longitudinal sectional front view of a conventional optical deflection device. 13...Housing part, 14...Hollow part (storage space), 15...Fixed shaft part, 16...Rotating body part,
17... Magnetic thrust bearing section, 18... Dynamic pressure gas journal bearing section, 19... Rotation drive section, 20...
...Rotating body fixed part, 23... Fixed shaft, 28... Rotating body.

Claims (1)

[Claims] 1. A housing part, a fixed shaft part having a cylindrical fixed shaft with one end fixed to the inner end surface of the housing part, a cylindrical rotating body loosely inserted into the fixed shaft, and a rotating body coaxial with the rotating body. A rotating body part having a polygon mirror fitted onto the outside, a magnetic bearing rotor attached to the rotating body, and a magnetic bearing stator coaxially surrounding the magnetic bearing rotor and attached to the housing part. a magnetic thrust bearing part that supports and suspends the load in the axial direction of the rotating body part by a magnetic force formed between the magnetic bearing rotor and the magnetic bearing stator; a dynamic pressure gas journal bearing part that supports the radial load of the rotating body part in a non-contact manner and having a dynamic pressure generating groove; a rotor attached to the rotating body; and a stator attached to the housing part. a rotary drive unit that rotationally drives the rotary body unit; and a rotation drive unit that is attached to the housing unit and that allows the rotary body unit to be freely attached to and detached from the housing unit against a force that causes the rotary body unit to float due to the magnetic thrust bearing unit. a rotating body fixing part that is fixed to the rotating body, and the rotating body fixing part has a cylindrical abutting part having approximately the same diameter as the rotating body, and a rotating body fixing part that is screwed to the housing part and fixes the abutting part to the a threaded portion that is coaxial with the rotating body and supports the one end of the rotating body so as to be able to move toward and away from the rotating body; An optical polarizing device comprising: an annular protruding seat on which the other end of the pushed-down rotating body is seated;