JPS61269116A - Device for supporting rotary body - Google Patents

Abstract

PURPOSE:To prevent a polygonal mirror or the like from damage due to impact force at the carrying time of a device and to improve the reliability of the device by forming cushioning members having double structure on both the sides of a rotary assembly body. CONSTITUTION:The cushioning member 70 consists of a wear resisting member 71 arranged on the rotary assembly body 50 side and an elastic member 72 arranged on the outside of the member 71, i.e. on the motor casing side and the elastic member 72 side is fixed on the inside of the motor casing 30 by a bonding agent. The upper cushioning member is fixed on a fixed shaft 40 at its center part and the peripheral part of the lower cushioning member is pressed by a motor driving circuit substrate 63. When the rotary assembly body is moved in its axial direction due to vibration or the like, the movement is cushioned by the cushioning member 70 to protect the rotary assembly body. Since the cushioning member is constituted of the double structure arranging the high wear resisting material on its inside, the device is prevented from the generation of shavings due to contact with the rotary assembly body and mixing of them into the bearing part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotating body support device suitable for supporting a rotating body that rotates at high speed, such as a rotating polyhedral optical deflector.

[Technical Background of the Invention] In recent years, the amount of information that needs to be transmitted and recorded has increased significantly in various industrial fields. Along with this, the speed of printers, which are a type of information recording equipment, has rapidly increased, and recently, laser printers capable of high-speed printing of 10,000 lines per minute or more have been realized.

As shown in FIG. 5, the laser printer includes a laser light source 1, a rotating polygon mirror device 3 that deflects a laser beam 2 emitted from the laser light source, and an imaging lens unit (f) that forms an image of the deflected laser beam. -θ lens) 4 and a photoreceptor 5 that is scanned by a laser beam passing through this lens unit, and a rotating polygon mirror device 3 that rotates the photoreceptor 5, which has been uniformly charged in advance, at high speed.
An electrostatic latent image is formed on the photoreceptor 5 by scanning with a laser beam 2 deflected by.

FIG. 6 shows a specific example of the configuration of the rotating polygon mirror device 3 described above. In the figure, the lower end of the fixed shaft 10 is attached to part 1.
The upper end mounting portion 0a and the upper end mounting portion 10b are fitted into mounting holes 13a and 13b provided through the motor casing 11 and a cover 12 that closes the upper end thereof, respectively, and are fixed by fixing screws 14.

Slightly inside the lower and upper ends of the fixed shaft 10, journal portions 16a, 1 have herringbone grooves 15 carved in the upper and lower ends.
6b is formed. The herringbone grooves 15 are carved in pairs so that their arrow-shaped tips face the rotational direction of the rotating assembly, which will be described later, to form a hydrodynamic air journal bearing.

A hollow cylindrical cylinder 7 is loosely fitted into the identification shaft 10 with a clearance of about 3 μm to 7 μm with respect to the journal portions 16a and 16b.

This cylinder has a motor magnet rotor 18).

are fixed, and the polyhedron 19 and the inner magnetic ring 20a of the thrust load supporting magnetic bearing 20 are fitted and bonded. Further, an outer magnetic ring 20b is installed inside the motor casing 11 to face the inner magnetic ring 20a.

Drive coils 21 are arranged outside the motor magnet rotor 18 at appropriate intervals. Electric power is input to this drive coil through a motor drive circuit board 23 suspended by a fixing screw 22 within the cover 12, and the motor magnet rotor 18 and the polyhedral rotor 19 connected thereto via a cylinder 17 are driven at high speed. Rotate.

A window 11a is formed in the motor casing 11 at a position outside the polyhedron 19 to allow the laser beam to pass therethrough.

24 indicates a fixing screw for transportation. This fixing screw is normally loosened as shown in Figure 6, and its tip and cylinder 17
An appropriate distance is maintained between the cylinder 17 and the ring-shaped Fg 17a, but when transporting the rotating body support device, the tip is screwed into the ring-shaped groove 17a to a position where it presses against the cylinder 17 and the motor magnet rotor. 18. Polyhedral technique 1
9 and an inner magnetic ring 20a.
to prevent movement in the thrust direction.

In the rotating body support device configured as described above, when power is supplied to the drive coil 21 through the motor drive circuit board 23, a rotational force is generated in the motor magnet rotor 18, and the rotation assembly 25 rotates.

As mentioned above, the rotating assembly 25 is supported by a herringbone groove type hydrodynamic air journal bearing with a minute gap of about 3 μm to 7 μm, so that when the rotating assembly 25 starts rotating, the air flows through the herringbone groove 15. The air flow sucked into the minute gap increases the pressure at the center of the bearing, and this pressure distribution causes a radial force to act on the inner surface of the cylinder 17.

On the other hand, the rotating assembly 25 is maintained in a state balanced with the thrust load by the attraction force between the magnetic ring 20a fixed to its lower end and the outer magnetic ring 20b fixed to the motor casing 11 side. When the solid body 25 begins to rotate and the pressure of the hydrodynamic air journal bearing increases, the cylinder 17 comes into a completely non-contact state with the journal portions 16a, 16b of the fixed shaft 10, and shifts to high speed rotation.

[Problems in the Background Art] However, in the conventional rotating body support device configured as described above, high precision is required for the dimensional accuracy of the inner and outer diameters of the bearing part, cylindricity, coaxiality, etc. If the bearing part is long, the machining time will be longer, which will reduce mass productivity, and will also increase the size and weight of the structure. Furthermore, since the thrust magnetic bearing 20 is installed separately on the motor casing 11 side and on the rotating assembly 25 side, the drive coil 10 may not rotate unless it stands vertically. The rotating assembly supported by hydrodynamic air bearings and magnetic journal bearings was prone to move in the thrust direction due to vibrations during equipment transportation, and there was a risk that it would collide with the stationary side, disrupting the accuracy of polyhedral techniques or destroying it. . For this reason, a transportation fixing screw 24 is provided to lock the rotating assembly from the outside of the casing, but in this case, the disadvantage is that the fixing screw must be loosened each time the device is transported. there were.

[Objective of the Invention] The present invention has been made to eliminate the above-mentioned drawbacks in the back weight technology, and provides a highly reliable rotating body support device that is small, easy to mass produce, and can withstand high-speed rotation. It is a conflict whose purpose is to

[Summary of the Invention] In order to achieve the above-mentioned object, the rotating body support device of the present invention prevents polyhedral techniques due to impact force during device transportation by providing buffer members with a three-position structure on both ends of the rotating assembly. It is characterized by preventing destruction and improving reliability.

[Embodiments of the Invention] The present invention will be described in detail below with reference to FIGS. 1 to 4.

FIG. 1 shows a rotating polyhedral optical deflector to which the present invention is applied.

This optical deflector includes a motor casing 30 consisting of an upper casing 31 and a lower casing 32 that closes the lower end of the motor casing 30, and is installed in the center of the casing, and the lower and upper ends are fixed to the motor casing 30 by fixing screws 33. a fixed shaft 40, a rotating assembly 50 fitted onto the fixed shaft, and a drive mechanism 6 for rotating this rotating assembly.
It is composed of 0. Reference numeral 70 indicates buffer members disposed at both ends of the rotating assembly.

The fixed shaft 40 is made of a very hard material that has been surface hardened with cemented carbide or silicon nitride, and has a single journal portion 41 formed slightly above the center in the axial direction, as shown in FIG. . A herringbone groove 42, which is inclined in the direction of rotation of the rotary assembly 50 from the upper and lower ends to the vicinity of the center part, is cut in this journal part to a depth of several μm. In addition, a fixed side magnetic ring 43 of a magnetic bearing for supporting a thrust load is provided in a small diameter portion formed on the lower side of the journal portion 41.
is fitted onto the outside and fixed with adhesive or the like.

The rotating assembly 50 includes a cylinder portion 51 as shown in FIG.
A polyhedral body 52 with , and a motor magnet rotor 55 that is fitted and fixed to the outside of the cylinder portion 51.

The bearing portion 53 is made of a very hard material like the fixed shaft 4o described above, and its inner diameter is equal to that of the journal portion 4 of the fixed shaft 40.
The dimensions are such that a minute gap of about 3 μm to 7 μm is formed with respect to the outer diameter of 1.

Furthermore, the inner diameter of the rotating magnetic ring (outer ring) 54 is dimensioned to form an appropriate minute gap between it and the stationary magnetic ring (inner ring) 43, and these magnetic rings 54, 43
As shown in FIG. 1, they are arranged to face each other to form a magnetic bearing for supporting a thrust load.

The drive mechanism section 60 includes magnetic poles 61 installed at predetermined intervals in the circumferential direction so as to surround the motor magnet rotor 55, drive coils 62 attached to these magnetic poles, and current supplied to these drive coils. The motor drive circuit board 63 is fixed to the lower casing 32 with screws.

The buffer members 70 each include a wear-resistant member 71 on the rotating assembly 50 side, an elastic member 72 on the outside thereof, that is, the motor casing side, and the elastic member 72 side is attached to the motor with an adhesive. It is fixed to the inner surface of the casing 30. Further, the upper buffer member has its central portion fixed by the fixed shaft 40, and the lower buffer member has its peripheral portion pressed by the motor drive circuit board 63.

Note that the upper casing 31 of the optical deflector includes a light entrance section 80 equipped with a laser emitting unit 81, as shown in FIG.
Light emitting unit 9 equipped with a lens unit (f-θ lens) 91
0 are airtightly fixed, and clean air is sealed inside the casing.

As described above, in the rotating body support device of the present invention, a hydrodynamic air journal bearing is formed between the journal portion 41 of the fixed shaft 40 and the bearing portion 53 of the rotating assembly 50, and
Fixed side magnetic ring 43 fitted to the fixed shaft and rotating assembly 5
Rotating side magnetic ring 5 fixed inside the cylinder 51 of 0
4 forms a magnetic bearing for supporting thrust loads, so drive the motor through the circuit board 63 for driving the motor. lJ
When a rotating magnetic field is generated in the mechanism section 60, the motor magnet rotor 55 is attracted to it and rotates, and the polyhedral technique 5
2 also rotates. Therefore, the laser beam incident from the laser emitting unit 81 is reflected by the polyhedron 52 rotating at high speed, and is emitted from the light emitting section 90 through the lens unit (f-theta lens) 91 to scan the photoreceptor.

Above) f, in the rotating body support device of the present invention,
Since the fixed shaft is short and only one journal portion of the hydrodynamic air journal bearing is formed, the time required for machining the bearing portion is shortened and mass productivity is improved. In addition, the axial length of the rotating assembly is shortened, and its center of gravity is located at the bearing portion 53.
Since the rotary assembly can be placed near the center of the rotor, a compact and well-balanced rotating assembly can be constructed.

Further, when the rotating assembly moves in the axial direction due to vibration or the like, the movement is buffered and protected by the buffer member 70. Moreover, since the buffer member has a double structure, and the inner side is made of a highly wear-resistant material, there is no possibility that shavings will be generated by contact with the rotating assembly and mixed into the bearing portion.

Further, since the buffer member is bonded to the motor casing and fixed by the fixed shaft 40 or the motor drive circuit board 63, it can be prevented from coming into contact with the rotating assembly even if the adhesive peels off over time.

Note that the rotating body support device of the present invention is not limited to the above series of laser printers, but can be widely applied to supporting various high-speed rotating bodies.

[Effects of the Invention] As described above, according to the present invention, it is possible to construct a rotating assembly that is small and well-balanced and has excellent mass productivity, and also prevents damage or distortion due to collision even if the rotating assembly moves in the axial direction. This can be prevented and the reliability of the rotating body support device can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a W1 sectional view showing an embodiment of the present invention, FIG. 2 is a side view showing the fixed shaft in FIG. 1, FIG. 3 is a perspective view showing the rotating assembly in FIG. 1, and FIG. 4 is a side view showing the fixed shaft in FIG. FIG. 5 is a perspective view illustrating a laser printer to which the rotating body support device of the present invention is applied, and FIG. 6 is a conventional one. FIG. 1...Laser light source 2...Laser beam 3...Rotating polygon mirror device 4...Lens unit 5...Photoreceptor 10.40...Fixed shaft 11.30...Motor casing 15. 42...Herringbone grooves 16a, 16b, 41 =--Journal portion 17.51
... Cylinder 18.55 ... Motor magnet rotor 19.52
...Polyhedral technique 20...Magnetic bearing for thrust load support 20a, 54.
...Rotating side magnetic ring 20b, 43...Fixed side magnetic ring 21.62...Drive coil 23.63...Motor drive circuit board 24...Fixing screw for transportation 25.50...Rotation Assembly 53...bearing part 60...drive mechanism part 61...magnetic pole 7.0...buffer member 71...wear-resistant member 72...elastic member 80...light entrance part 81 ... Laser emitting unit 90 ... Light emitting part

Claims (2)

[Claims] (1) A rotating assembly including a fixed shaft, a motor rotor that is fitted onto the fixed shaft and rotates around the fixed shaft, and one magnetic ring of a magnetic bearing for supporting thrust loads, and this rotating assembly. In a rotating body support device comprising a drive mechanism for rotation and buffer members disposed on both ends of the rotating assembly to soften the impact when the rotating assembly moves in the thrust direction, the buffer member provides wear resistance to the rotating assembly side. 1. A rotating body support device comprising a flexible member and an elastic member on the outside thereof. (2) The rotating body support device according to claim 1, wherein the buffer member is bonded to the inner surface of the motor casing and fixed by a fixed shaft.