JP3181004B2 - Bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device of, for example, a pneumatic type.

[0002]

2. Description of the Related Art In recent years, ceramic thrust bearing devices have
Due to the low density of ceramic, it is expected as a bearing device suitable for high-speed rotation because of its light weight, low inertia performance, and the like. In particular, in recent years, OA devices such as a video tape recorder (VTR), a floppy disk drive (FDD), and a laser beam printer (LBP), which are being miniaturized, require light, thin and short bearing devices. As such a bearing device, there is a thrust bearing device having a spiral groove, and it is possible to achieve stable high-speed rotation with a compact configuration.

As a thrust bearing device, for example, an air dynamic pressure type thrust bearing device disclosed in Japanese Patent Application Laid-Open No. 3-28516 is known. In the pneumatic thrust bearing device disclosed in this publication, the thrust bearing and / or the thrust collar have a porous structure in order to eliminate excessive starting torque.

[0004] For example, Japanese Patent Publication No. 64-2815 discloses a bearing device in which a metal film is formed on a ceramic rolling surface, and the rolling stress is reduced by forming a metal film on the rolling surface. Durability has been improved.

[0005]

However, the above-mentioned prior art merely solves the problem of stress. If a bearing is formed using ceramics having high electrical insulation, static electricity is generated during high-speed rotation. OA equipment generates noise due to sparks generated in the bearings,
There is a problem that OA equipment is adversely affected.

An object of the present invention is to provide a bearing device that can prevent occurrence of spark.

[0007]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that an oxide semiconductor having a predetermined thickness and a predetermined surface resistance on the surface of a thrust bearing and / or a thrust collar. The present inventors have found that the formation of a thin film or an ultrathin metal film can prevent the generation of sparks at the time of high-speed rotation, leading to the present invention.

That is, a bearing device according to the present invention is a bearing device comprising a ceramic thrust bearing and a ceramic thrust collar, wherein a surface of the thrust bearing on the thrust collar side and / or a thrust bearing of the thrust collar is provided. On the side surface, an oxide semiconductor thin film having a thickness of 10 to 500 nm and a surface resistance of 10 ⁶ Ω or less is formed.

Further, the bearing device according to the present invention is a bearing device comprising a ceramic thrust bearing and a ceramic thrust collar, wherein a surface of the thrust bearing on the thrust collar side and / or a thrust bearing of the thrust collar is provided. The side surface has a thickness of 1 to 50 nm and a surface resistance of 10
^It is formed by forming an ultra-thin metal film of ⁶ Ω or less.

The ceramic thrust bearing and thrust collar used in the present invention are, for example, Al ₂ O ₃ , S
It is formed from a sintered body or the like mainly composed of i ₃ N ₄ , SiC, ZrO ₂ , but is not limited thereto, and may be other known ceramic materials conventionally used for the thrust bearing and the thrust collar. .

The oxide semiconductor thin film formed on the surface of the thrust bearing and the thrust collar is, for example, SnO 2
_{2, NiO, Cr 2 O 3} , Cu 2 O, MnO 2, Zn
O, V ₂ O ₅ , Fe ₂ O ₃ , TiO ₂ , BaTiO ₂ ,
CoO, CdO, or the like is used, and is formed by, for example, an ion beam sputtering method, a magnetron sputtering method, or an ion beam assisted deposition method.

Further, the thickness of the oxide semiconductor thin film is set to 10 to 5
The reason for setting the thickness to 00 nm is that if the oxide semiconductor thin film is smaller than 10 nm, the effect as a conductive film cannot be obtained, and the charge removal effect is small. Also, when the thickness of the oxide semiconductor thin film is larger than 500 nm, the surface hardness is reduced and the wear resistance is deteriorated. The oxide semiconductor thin film preferably has a thickness of 10 to 300 nm from the viewpoint of abrasion resistance, and more preferably has a thickness of 10 to 300 nm.
Desirably, it is 00 nm.

In the bearing device of the present invention, the surface of the thrust collar on the thrust collar side and / or the surface of the thrust collar on the thrust bearing side may have a thickness of 1 to 50 nm and a surface resistance of 10 ⁶ Ω or less. Although a thin film is formed, a metal ultra-thin film having a thickness of 1 to 50 nm is formed by
This is because if the metal ultrathin film is smaller than 1 nm, the effect as a conductive film cannot be obtained, and the charge removal effect is small. On the other hand, if the thickness of the ultrathin metal film is more than 50 nm, the surface hardness decreases and the wear resistance deteriorates. The ultrathin metal film is preferably 1 to 30 nm from the viewpoint of abrasion resistance, and particularly preferably 1 to 2 nm.
Desirably, it is 0 nm.

The ultra-thin metal film is made of, for example, Ni, Cu, P
d, Ag, Pt, Au, Al, Si, C, Cr, Co,
It is made of Ti and formed by, for example, an ion beam sputtering method, an ion mixing method, or the like.

Further, the surface resistance of the oxide semiconductor thin film and the ultrathin metal film is set to 10 ⁶ Ω or less because the surface resistance is 1
If it is higher than 0 ⁶ Ω, the effect as a conductive film cannot be obtained, and the charge removal effect is small. The surface resistance of these thin films is 10 ⁵ Ω in order to effectively remove static electricity.
It is desirable that:

[0016]

In the bearing device of the present invention, the static electricity generated in the thrust bearing and the thrust collar by the high-speed rotation is caused by the oxide semiconductor thin film and the metal on the thrust collar side surface of the thrust bearing and / or the thrust bearing side surface of the thrust collar. Static electricity is removed through the ultra-thin film. Thereby, when the bearing device is mounted on the OA equipment, it is possible to prevent adverse effects on the OA equipment due to static electricity.

[0017]

【Example】

Embodiment 1 FIG. 1 shows an embodiment of the bearing device of the present invention, and reference numeral 1 indicates a rotating shaft. A ceramic thrust collar 2 is formed integrally with the rotating shaft 1, and a ceramic thrust bearing 3 is disposed below the thrust collar 2. The thrust collar 2 and the thrust bearing 3 are made of, for example, Al ₂ O ₃ , Si ₃ N ₄ ,
It is formed from a sintered body such as C or ZrO ₂ .

The thrust collar 2 of the thrust bearing 3
A spiral groove 4 is formed on the side surface (the upper surface of the thrust bearing 3), as shown in FIG.

As shown in FIG. 3, the surface of the thrust collar 2 on the thrust bearing 3 side and the surface of the thrust bearing 3 on the thrust collar 2 side have a thickness of 10 to 500 nm and a surface resistance of 10 ⁶ Ω or less. An oxide semiconductor thin film 5 is formed. This oxide semiconductor thin film 5 is made of, for example, SnO ₂ ,
NiO, Cr ₂ O ₃ , Cu ₂ O, MnO ₂ , ZnO, V
₂ O ₅ , Fe ₂ O ₃ , TiO ₂ , BaTiO ₃ , Co
It is made of O, CdO, or the like, and is formed by, for example, an ion beam sputtering method.

On the side surfaces of the thrust collar 2 and the thrust bearing 3, an oxide semiconductor thin film 6 for grounding the charged static electricity is formed.

In the bearing device formed as described above, the spiral groove 4 formed in the thrust bearing 3 is rotated by high speed rotation.
The air is entrained from the outer periphery to form an air bearing.

Then, the static electricity generated in the thrust bearing 3 and the thrust collar 2 by the high-speed rotation is caused by the oxide semiconductor thin film 5 on the thrust collar 2 side surface of the thrust bearing 3 and the thrust bearing 3 side surface of the thrust collar 2, The static electricity is removed through the oxide semiconductor thin film 6 formed on the side surfaces of the bearing 3 and the thrust collar 2, so that a spark in the bearing device can be prevented, and noise in the OA equipment can be prevented.

The present inventor has sought to confirm the effects of the present invention.
A thrust bearing and a thrust collar are formed of ceramics as shown in Table 1, and an oxide semiconductor thin film having a material, thickness and surface resistance as shown in Table 1 is formed on the thrust bearing and thrust collar. One minute of noise generated when such a bearing device was incorporated into a magnetic head drum of a VTR was counted. Also,
The surface hardness was measured with a micro Vickers hardness tester.
Table 1 shows the results.

[0024]

[Table 1]

As is clear from Table 1, when the thickness of the oxide semiconductor thin film is less than 10 nm, the effect of the conductive film cannot be obtained, so that the surface resistance is high and the number of noises generated per minute is 100. And many. When the thickness is hotter than 500 nm, the surface hardness is reduced, the abrasion resistance is poor, and the practicality is poor.

[0026] Example 2 thick instead the surface resistance is less than the oxide semiconductor thin film 10 ⁶ Omega in 10 to 500 nm, thickness using a surface resistance of 10 ⁶ Omega following ultrafine metal thin film 1~50nm A bearing device was formed in the same manner as in Example 1 except for the above. Even with such a bearing device, the same effect as in the first embodiment can be obtained.

Therefore, the present inventor formed the thrust bearing and the thrust collar with ceramics as shown in Table 2, and formed an ultrathin metal film having the material, thickness and surface resistance as shown in Table 2. Occurred when such a bearing device was incorporated into the magnetic head drum of a VTR.
The minute noise was counted. Table 2 shows the results.

[0028]

[Table 2]

As is apparent from Table 2, when the thickness of the ultrathin metal film is less than 1 nm, the effect of the conductive film cannot be obtained, so that the surface resistance is high and the number of noises generated per minute is 10%.
There are as many as 0. When the thickness is more than 50 nm, it is found that the surface hardness is reduced, the wear resistance is poor, and the practicability is poor.

In the first and second embodiments, the example in which the thrust bearing and the thrust collar are formed of the same material has been described. However, it is needless to say that the thrust bearing and the thrust collar may be formed of different materials. In the first and second embodiments, an example in which an oxide semiconductor thin film and an ultrathin metal film are formed on both surfaces of the thrust bearing and the thrust collar has been described. However, the oxide semiconductor thin film is formed on either the thrust bearing surface or the thrust collar surface. Alternatively, needless to say, a metal ultra-thin film may be formed.

[0031]

As described above in detail, in the bearing device of the present invention, the static electricity generated in the thrust bearing and the thrust collar by the high-speed rotation causes the surface of the thrust bearing on the thrust collar side and the surface of the thrust collar on the thrust bearing side. Static electricity is removed through the oxide semiconductor thin film or the ultrathin metal film, so that spark in the bearing device can be prevented, and noise in OA equipment can be prevented, thereby contributing to high quality OA equipment.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a bearing device of the present invention.

FIG. 2 is a plan view of the thrust bearing of FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a part of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rotary shaft 2 ... Thrust collar 3 ... Thrust bearing

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16C 17/00-17/26 F16C 33/00-33/28 H02K 5/00-5/26 H02K 7 / 00-7/20

Claims (2)

(57) [Claims] 1. A bearing device comprising a ceramic thrust bearing and a ceramic thrust collar,
The thickness of the thrust bearing on the thrust collar side surface and / or the thrust bearing side surface of the thrust collar is 10
A bearing device comprising an oxide semiconductor thin film having a surface resistance of 10 ⁶ Ω or less at a thickness of 500 nm or less. 2. A bearing device comprising a ceramic thrust bearing and a ceramic thrust collar.
The thickness of the thrust bearing on the thrust collar side surface and / or the thrust bearing side surface of the thrust collar is 1 to 1.
A bearing device comprising a metal ultra-thin film having a surface resistance of 10 ⁶ Ω or less at 50 nm.