JPS61105308A - Supporting device of rotary body - Google Patents

Abstract

PURPOSE:To endure high-speed revolution operation by reinforcing one or both sides of a magnetic member which constitutes a magnetic thrust bearing, by use of a strength member. CONSTITUTION:A motor stator 32a having a driving coil 45 and a yoke 46 is fit to a cover 51 which closes the upper open part of a motor housing 34 in such a manner that the stator surrounds a motor rotor 38. The state is so arranged as to have a rotary assembly 47 driven, while said assembly being consisting of a cylinder 37, a motor rotor 38, a polynomial mirror 31, an internal magnetic ring 40, plate-like ring (strength member) 42, and so on. An external magnetic ring 43 serving as a secondary magnetic member is so mounted as that it surrounds the internal magnetic ring 40, whereby constituting the magnetic thrust bearing 39 of the rotary assembly 47.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention is applied to, for example, a rotating polyhedral mirror light deflector,
The present invention relates to a rotating body support device that supports a rotating body such as a polyhedral mirror.

[Technical background of the invention and its problems]

In recent years, the amount of information has increased significantly, and accordingly, printers that record information are required to be faster each year. In recent years, laser beam printers capable of high-speed printing of 10,000 lines per minute or more have been developed, and have achieved considerable success.

This laser beam printer usually deflects a laser beam (laser beam) 2 emitted from a laser light source 1 via a polygonal mirror rotating type optical deflector 3, as shown in FIG. The light 2 is scanned through an imaging lens unit (FO lens) 4 onto a photoreceptor 5 which has been uniformly charged in advance, and an electrostatic latent image is formed on the photoreceptor 5.

The optical deflector 3 is composed of a polygonal mirror 6 and a motor 7 for rotating the polygonal mirror 6 at high speed, and has a configuration as shown in FIG. 11.

That is, the polyhedral mirror 6 includes a mirror adapter 9 fitted onto the upper end tapered portion 8a of the motor shaft 8 of the motor 7, and a nut 1 screwed onto the upper end threaded portion 8b of the motor shaft 8.
It is held in place by a mirror holding body 11 which is pressed by the mirror holder 11. Further, a motor rotor 12 is attached to the axially central portion of the motor shaft 8, and a motor stator 14 is attached to the motor housing 13 side surrounding the motor rotor 12.
It constitutes a shaft drive section 15 that drives the motor shaft 8.

Additionally, Herring-Pone type dynamic pressure air journal bearings 16.16 are provided in both the upper and lower directions of the shaft drive section 15, and support the motor shaft 8 in the radial direction.

That is, the motor shaft 8 has group forming portions gc and sc formed with dogleg-shaped herring pawn groups 17 on its circumferential surface, and these group forming portions gc and IIC are arranged so as to face each other. A cylindrical bearing member 18, 18 is attached to the motor housing 13 so as to surround the motor housing 13 with a small gap of several microns in the surface.

In addition, several inner magnet rings 19 are fitted to the lower end of the motor shaft 8, and are held by a ring retainer 21 attached to the lower end surface of the motor shaft 8 via bolts 20. On the motor housing 13 side, several outer magnet rings 22 are provided so as to surround these inner magnet rings 19 with a gap of approximately several hundred microns between their mutually opposing surfaces. The inner magnet ring 19 and the outer magnet ring 22 are magnetized so that they melt and exert an attractive force. These attractive forces constitute a magnetic thrust bearing 23 that receives the axial force (mainly its own weight) of the motor shaft 8 and supports the motor shaft 8 in a suspended state.

Further, the outer magnet ring 22... is held by a ring holder 24, and this ring holder 2
4 is slidably fitted into the holder fitting portion 25 of the motor housing 13.

The motor housing 13 includes a housing body 13a having a stepped hole, an end plate (motor end plate) 13b that closes a lower opening of the housing body 13a, and a motor end plate that closes an upper opening of the housing body 13a. It consists of a cap 13G.

- In the above configuration, when the motor shaft 8 starts to rotate, the ring-pone type hydrodynamic air journal bearing 16. By flowing into the gap of ~6 μm, the pressure distribution inside the gap becomes high at the center of the bearing, and this pressure causes a force in the radial direction.

On the other hand, the motor shaft 8 is in a state where the suction force and thrust load of the inner magnet ring 19 attached to the lower end of the motor shaft 8 and the outer magnet ring 22 attached to the motor 1 clamping 13 side are balanced. It is maintained in Therefore, the motor shaft 8 is in a non-contact state 40
0 (l rpm ~ 15000 rpm can be continued at high speed rotation.

Thus, a cover 26 is attached to the upper end side of the motor shaft 8 and serves as a cover (-therefore, the enclosed polyhedral mirror 6
is rotated at high speed to deflect the laser beam 2 at high speed.

However, the conventional configuration described above has the following problems. In other words, magnets generally have a large specific gravity,
Because many materials are brittle, they often break due to centrifugal force due to high-speed rotation, exceeding the tensile strength of the material, or even breaking due to small chips or cracks even under stress that is less than the material's strength.

For this reason, the rotational speed of the motor is limited by the strength of the magnet. Particularly in motors with rotor air bearings, the limit value of the rotational speed of the bearing itself is very high, and the strength of the magnet is important.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to provide a configuration that is easy to manufacture and inexpensive to handle the thrust load of a rotating body, yet can reliably support the thrust load in a non-contact state, and is stable over a long period of time. An object of the present invention is to provide a rotating body support device capable of supporting a rotating body.

[Summary of the invention]

In order to achieve such an object, the present invention reinforces one or both sides of the magnetic member constituting the magnetic thrust bearing with a strength member so that even a relatively weak magnet can withstand high-speed rotation. .

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 shows a polygonal mirror rotating type optical deflector, and this optical deflector 30 includes a polygonal mirror 31 and a polygonal mirror 3
1 at high speed in a predetermined direction (in the embodiment, clockwise when viewed from above), and has the following configuration.

33 in the figure is a fixed shaft, and the lower end attachment part 33 of this fixed shaft 33
a is fitted into the mounting hole 35 of the motor housing 34 and fixed with a screw 58.

This fixed shaft 33 is made of a non-magnetic material, and herringbone grooves 36.degree. 36 are formed at both upper and lower ends of the circumferential surface of the non-fitting portion. These herringbone grooves 36, 36 are formed in a shape with an arrow-shaped tip facing in the direction of rotation of the polygon mirror 3.

Further, a hollow cylindrical cylinder 37 made of a non-magnetic material and having an inner diameter dimension that forms a gap of 3 μm to 6 μm between the fixed shaft 33 and the outer diameter portion of the fixed shaft 33 is rotatably mounted on the fixed shaft 33. A motor rotor 38, a polyhedral mirror 31 . An inner magnetic ring 40 as a first magnetic member of a magnetic thrust bearing 39 constituting a rotating body support device for thrust support is attached as described later. It is fixed by shrink fitting, press fitting, etc. so that the inner peripheral edge of the upper end of the opening is in contact with the upper surface side of the flange J7a that protrudes slightly downward from the center in the direction.

Further, the motor rotor 38 is bonded to the cylinder 37 fitted into the cylinder 37 so as to come into contact with a rib 31a provided at the upper opening edge of the polyhedral mirror 3. In addition, the inner magnetic ring 40 has a plate-shaped ring 4 on the lower surface having approximately the same diameter as the inner magnetic ring 40.
The cylinder 37 is assembled with the strength member No. 2 bonded and reinforced.
It is inserted into the small diameter part of the lower end and glued.

On the other hand, a cover 51 that closes the upper end opening of the motor housing 34 has a state in which it surrounds the motor rotor 38 (a motor stator 3 equipped with two drive coils 45 and a yoke 46).
2a is attached, and includes a cylinder 37, a motor rotor 38, a polyhedral mirror 31, an inner magnetic ring 40. A rotating assembly 47, which is a rotating body composed of a plate-shaped ring 42, etc., is driven.

Further, an outer magnetic ring 43 as a second magnetic member is provided surrounding the inner magnetic ring 40 to constitute a magnetic thrust bearing 39 that supports the rotating assembly 47 in the thrust direction. The outer magnetic ring 43 is a stepped recess 3 formed in the motor housing 34.
4a and is fixed with adhesive, in this way,
By adhering a strength member to the lower surface of the magnetic ring 40 of the magnetic thrust bearing 39, it is possible to obtain strength capable of withstanding a rotational speed several times lower than the rotational speed that the magnetic ring alone can withstand. Furthermore, it is not necessary to pay much attention to small cracks and chips that tend to occur during processing and assembly of magnetic members. As described above, since the centrifugal force resistance of the magnetic member is greatly improved, there is no need to limit the number of revolutions of the motor as in the past.

In addition, A! as a strength member! If a non-magnetic material with relatively low specific gravity and high strength is used, the magnetic flux will not flow in vain and can be used effectively.

Furthermore, by reinforcing the magnetic member with a strength member, it becomes possible to use a material with relatively low strength, such as a magnetic member manufactured by resin molding. This makes it possible to take advantage of the advantages of resin molded products: high productivity, low cost, and stable quality. or,
In the case of molded products, there is no need for post-processing, so cracks and chips do not occur, and the number of inspection steps can be reduced. In addition, there is less adhesion of dust and iron powder, and the cleaning process can be simplified.

Further, as shown in FIGS. 4 and 5, a drive circuit board 50 that is electrically connected to the motor drive coil 45 is attached to the motor stator 32a. The surface is covered with an insulating resin coating (
(not shown in detail) to prevent foreign matter such as dust caused by peeling of the coating of the motor drive coil 45, flux scum and chips from the drive circuit board 50 from falling into the motor.

In addition, examples of materials for forming the above-mentioned insulating resin coating include:
Product name: Nl880-FB (Nippon Soda PC-10
We use butadiene-based materials such as liquid 1-2 melibdadiene (based on 00) or urethane-based materials that do not generate gas in the dry state to prevent the gas generated from having an adverse effect on the internal mechanism. .

Further, as shown in FIGS. 1 and 3, a hole 60 is formed in the lower part of the motor housing 34 and communicates with a chamber 6 formed on the bottom side of the motor housing 34. Department M
There is a desiccant 59 such as silica gel inside the plate 5.
It is sealed by 7. In addition, the motor housing 34
The upper end opening is sealed by an elastic sealing member 62, 63 such as rubber that seals the cover 51 and the extension SOa of the drive circuit board 50 from the cover 51, and the polyhedral mirror 31
and a closed container 52 as a cover that surrounds the drive mechanism section 32. Moreover, clean air is sealed inside this airtight container 52.

Note that the center hole 51a of the cover 51 is connected to the airtight container 5-
The upper end 33b of the fixed shaft 33 provided at the center of the cover 51 is fitted with a play, and a plate 49 that fits into the upper end 33b without a gap is formed at the center of the upper surface of the cover 51 during assembly. By adhering the fixed shaft 33 to the recessed portion, the fixed shaft 33 is fitted into the recessed portion without being affected by the positional accuracy of the fixed shaft 33. The upper end surface of the plate 49 is slightly higher than the upper end surface of the cover 51, and the cover 51 is fixed by a screw 64 screwed into the upper end surface of the fixed shaft 33.

Further, as shown in FIGS. 1, 4, and 5, the drive circuit board 50, which is electrically connected to the motor drive coil 45, has an extension extending outside the closed container 52 as a cover, as described above. It has an outlet SOa, and a connector 81 is attached to the tip thereof.

Therefore, compared to the conventional method in which lead wires are connected to the drive circuit board 50 and the lead wires are led out of the sealed container 52, there are no problems such as connection errors or disconnections, and the work is easy and reliable. It will be possible to do this.

Further, as shown in FIG. 2, a hole 34bl formed in the side surface of the motor housing 34 is provided with a laser generating unit portion 66 covered with a protective cover 65 made of an insulating material, and a laser generating unit portion 66 is attached as shown below. The laser generating unit section 66, in which the laser beam 48 emitted from the generating unit section 66 is guided to the polyhedral mirror 3, is constructed as follows. 67 is a semiconductor laser as a laser generating member, and this semiconductor laser 67 is attached to a disc-shaped laser holder 68. The laser holder 68 is in contact with the lens holder 71 with a smooth surface 611a.

The outer diameter of the laser holder 68 is smaller than the inner diameter of the concave portion of the lens holder 7I, and the outer periphery is pressed in a cross shape by four screws 69 screwed into the outer periphery of the lens holder 7I. It has a structure in which the plane of the recessed portion of the lens holder 71 can be moved by moving in and out. After adjusting the axis of the laser beam 48 of the semiconductor laser 67 and the optical axis of the collimator lens 72, v1] is determined by the screw 7o.

The collimator lens 72 is fitted into the cylindrical core part 71a of the lens holder 7, and is pressed against the spring material 73 inserted deep by a cylindrical screw 74 screwed into a threaded part on the inner circumference of the cylinder of the lens holder 71. , the distance from the semiconductor laser 67 can be adjusted. semiconductor laser 67
is connected to a circuit board 76 supported by a stud 75 attached to the laser holder 68.

These laser generating unit parts 66 are covered with a protective cover 65 made of an insulating material. The protective cover 65 has a cylindrical portion 65a fitted into the hole 34b of the motor housing 34, and the cylindrical core portion yza of the lens holder 71 inserted into the cylindrical portion 65a of the protective cover 65 is fixed to the cylindrical portion 6.
It is designed to be able to rotate around the axis of 5a. Screw the fixing screw 79 into the screw hole provided on the outer periphery of the hole 3-4b of the motor housing 34 to remove the protective cover 65.
Press strongly the outer periphery of the cylindrical part 65a to deform a part of the cylindrical part 65B (in a state where the laser generating unit part 66 and screws etc. do not come into direct contact with each other, that is, the laser generating unit part 66 is electrically It has a structure that allows it to be fixed at any position while being insulated from 34.

However, since the outer periphery of the laser generating unit section 66 is covered with a protective cover 65 made of an insulating material, the semiconductor laser 67 as a laser generating member is damaged by a minute external current.
can be reliably protected.

Further, as shown in FIG. 6, the laser generating unit section 66 (
- When the semiconductor laser 67 is rotated and displaced, the laser beam 4
It is designed to rotate around the center of the optical axis of 8.
When the semiconductor laser 67 is rotated by an angle of 0, a beam spot 4 with an elliptical light intensity distribution is created as shown in FIG.
8' changes from the state shown in Fig. 7 (a) to the state shown in Fig. 7 (01), and the dimension k in the long axis direction of the beam spot 48' can be adjusted to a smaller dimension A'<1!,>A'. It looks like this. Then, the variation in the diameter of the beam spot 48' in the long axis direction, that is, the variation in the diameter of the beam spot 48' in the sub-scanning direction, is corrected to maintain a constant size, so that high-quality image formation can be performed. be.

For example, if the diameter of the beam spot 48' is a specified diameter, for example 115 μm, as shown in FIG. Good image densities as shown in the figures are obtained.

However, if the diameter of the beam spot 48' is smaller than the specified diameter, for example 80 μm, the distance between the lines may become wider, as shown by AI, f3/, and C/ in FIG. The overlapping state between the line and the line may be impaired, making it impossible to obtain good image density. Furthermore, if the diameter of the beam spot 48' is larger than the specified diameter, the interval between lines becomes narrower when single-line scanning is performed, which also causes a problem that good image density cannot be obtained.

However, in this embodiment, if the diameter of the beam spot 48' varies more than a specified value, the semiconductor laser 67 is rotationally displaced so that the elliptical beam spot 48' is shifted in the sub-scanning direction. By correcting the length to a specified dimension, good image density can be obtained and clear images can be formed.

The reflected laser beam 48 hits the tQ plane of the polyhedral mirror 31 and is reflected by an imaging lens unit (Fθ lens) 54 as an optical imaging means, which is integrally attached to the motor housing 34. The imaged surface 56 of the photoreceptor etc. is passed through the through hole FA55 sealed by
Also, as shown in FIGS. 1 and 3, a rotating assembly fixing screw 53 is screwed into the side wall of the motor housing 34, and the tip of this screw is inserted into the side wall of the motor housing 34. By inserting the tapered portion into the groove provided in the ring 37, unnecessary vertical movement and rotational movement of the rotary assembly 47 during transportation can be restricted. Further, the imaging lens unit 54 as an optical imaging means is screwed into the first frame and the mounting flange 34C of the motor housing 34 as shown in FIG.
Screw 7 attached to stay 54b protruding from 4a
7, the imaging lens unit 54 can be rotated in a predetermined direction. An optical imaging means moving mechanism 80 is configured to move and adjust the mounting position of the imaging lens unit 54 in the direction toward and away from the polyhedral mirror 31. Therefore, by varying the distance between the imaging lens unit 54 and the imaging surface 56 such as a photoreceptor, the lens 54
It is possible to correct a shift in the focal point position due to variations in the refractive index of the glass material forming the C.... In addition,
Motor housing 34, plate body 57, motor housing 3
4 and the extending portion of the drive circuit board 50, and the screw insertion portion of the motor housing 34 and the cover 51 rotation assembly fixing screw 53, etc., have a sealed structure, but the parts where there is a possibility of a gap are sealed with silicone compound 78 or other sealing material. It has a structure that can be sealed to create a completely airtight structure.

Thus, the laser generating unit section 66, the imaging lens unit 54 as an optical imaging means, and the optical deflector 3Q can be integrated and completely sealed with a silicone compound 78 or the like. As mentioned above, since the cylinder 37 rotates at high speed with a gap of 3 μm to 6 μΩm between it and the fixed shaft 33, the inside of the airtight container 52 serving as a cover must be clean and free of dust, dirt, and moisture. However, by creating a sealed structure, it is possible to prevent dirt, dust, and moisture from entering from the outside.

Furthermore, the inside of the sealed container 52 becomes completely dry due to the action of the desiccant 59, and the moisture inside the sealed container 52 condenses, resulting in locking of the motor, corrosion of the mirror surface of the polyhedron, and damage to other parts.
It is now possible to prevent the occurrence of rust due to food consumption.

By energizing the motor drive coil 45, a circuit magnetic field is generated in the motor rotor 32a, and the cylinder 3
7. A rotating assembly 47 consisting of the motor rotor 38, inner magnetic ring 40, etc. is driven clockwise. When this rotating assembly 47 rotates, air flows into the gap between the fixed shaft 33 and the cylinder 37 due to the action of the herringbones g3g and 36, air pressure is generated in the radial direction, and an air dynamic pressure journal is generated in these parts. The rotating assembly 47 is supported by a magnetic thrust bearing 39 in the thrust direction, while a bearing is formed in the magnetic thrust direction.

Therefore, the rotating assembly 42 can be supported in a non-contact state with respect to the fixed shaft 33 (2), and a stable shaft 4, 41 can be supported.
'o1 It is something that can be rolled.

Thus, the polyhedral mirror 31 is rotated at a controlled speed to deflect the laser beam 48 emitted from the laser generation unit section 66. Note that the deflected laser beam 48
is led out to the image-forming surface side of the photoreceptor or the like through a through hole 55 that is sealed by an imaging lens unit 54 formed in the motor housing 34 .

Note that the present invention is not limited to the above embodiments.

That is, although an example has been described in which the rotating assembly 47 as the first rolling body is attached to the inner magnetic ring 40 side as the first magnetic member, the invention is not limited to this. The same purpose can be achieved even if the magnetic member c2 is attached to the outer magnetic ring 43 side as a magnetic member, the inner magnetic ring 4o is fixed, and the outer magnetic ring 43 side is rotatable.

It goes without saying that the present invention may also be applied to rotating bodies other than polyhedral mirrors.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist of the invention.

〔Effect of the invention〕

As explained above, the present invention has a first magnetic member and a second magnetic member provided to surround the first magnetic member, and either one of the magnetic members is rotatable with a rotating body. A rotating body support device configured to support the rotating body in the thrust direction by a magnetic thrust bearing attached to the rotating body, wherein both sides or one side of the magnetic member attached to the rotating body are each reinforced with a strength member. It is structured as follows. Therefore, by reinforcing the magnetic members constituting the magnetic thrust bearing with a strength member, even a relatively weak magnetic member can withstand high rotational speeds, and the thrust load of the rotating body can be easily manufactured and manufactured at low cost. It is possible to provide a rotating body support device that can reliably support the rotating body in a non-contact state and can support the rotating body for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view showing the configuration of the main parts of a scanning optical device that employs the rotating body support device of the present invention, FIG. 2 is a T plan view also partially sectional, and FIG. 4 is a bottom view showing the configuration of the main part of the optical deflector, and FIG. 5 is a side view showing the same partially in section.
Figure 6 is a front view of the laser generation unit, Figure 7 is an explanatory diagram showing the state of the beam spot as the laser generation member rotates, and Figures 8 and 9 are diagrams showing the beam spot diameter and image density, respectively. FIG. 10 is a schematic diagram of an optical scanning system, and FIG. 11 is a schematic longitudinal sectional side view showing a conventional optical deflector to which a conventional device is applied. 39...Rotating body support device (magnetic thrust bearing') 40
...first magnetic member (inner magnetic ring), 47...
Rotating assembly as a rotating body, 42... strength member (plate-shaped ring), 43... second magnetic member (outer magnetic ring). Applicant's representative Patent attorney Takehiko Suzue Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) A magnetic device that has a first magnetic member and a second magnetic member that surrounds the first magnetic member, and a rotating body is rotatably attached to one of the magnetic members. A rotating body support device that supports the rotating body in the thrust direction by a thrust bearing, characterized in that one or both sides of the magnetic member on the rotating body side is reinforced with a strength member. (2) The rotating body support device according to claim 1, wherein the magnetic member is made of resin. (3) The rotating body support device according to claim 1, wherein the strength member is a non-magnetic material.