JPS592276A - Turntable device - Google Patents

Abstract

PURPOSE:To obtain a turntable having a small thickness with a simple constitution suitable for a high-density recording medium such as a video disk, etc., by holding the turntable with a planar static pressure gas bearing part which acts directly on the rear side of the turntable and a hemispherical static pressure gas bearing part. CONSTITUTION:First the compressed gas (air) for bearing is supplied through gas feed paths 8 to actuate the planar and hemispherical static pressure gas bearing parts 9 and 10. Then a turntable 25 and a hemisphere 30 are controlled to be set at a prescribed position respectively. Then a motor 37 is driven, and therefore a rotary shaft 12 is revolved via a coupling 38. Then the table 25 is revolved. The table 25 is restricted in the thrusting direction by the parts 9 and 10 and also always kept horizontal by the part 9. A slight tilt of the shaft 12 is restored vertically owing to an unbalance of the pressing force of the part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotary table device which is suitable for supporting and rotating a high-density recording medium such as a video disk, and which has a simple and thin structure.

[Prior Art and Its Problems] Recently, rotary table devices have been developed that rotate high-density recording media, such as disk members such as video disks, with high precision with extremely little axial vibration.

These devices have extremely complicated groove structures that require high accuracy on the order of several micrometers, are large in size, and are therefore expensive.

[Object of the Invention] The present invention has been made to eliminate the above-mentioned disadvantages, and an object thereof is to provide a rotary table that has high precision performance, is simple in construction, thin γ, and inexpensive.

[Summary of the Invention] The present invention provides a rotary table by directly supporting the lower surface of the rotary table with a hemispherical silent pressure gas bearing, and supporting the lower part of the rotary shaft for rotating the rotary table with a hemispherical silent pressure gas bearing. The rotary table is extremely thin and has a simple structure, and by engaging the rotary table and the rotary shaft with a part of the spherical surface, the rotary table is always kept horizontal even when the rotary shaft is slightly tilted. Embodiments of the Invention The details of the present invention will be explained below with reference to an illustrated embodiment. (
1) is a main body made of a disc-shaped member, and the upper end surface is formed into a circular flat bearing plane (2) with a slight step. Further, the back surface (3) is provided with a bearing spherical surface (4) formed by a part of a concave spherical surface having a central axis perpendicular to the bearing plane (2) and opening here. A shaft hole (5) penetrating the bearing spherical surface (4) is bored in the center. Furthermore, one end of the main body (1) communicates with an external compressed air source, and the other end opens at a plurality of locations on the bearing plane (2) and the bearing spherical surface (4).
)..., (force...) multiple gas supply channels (8
)... is provided. And these spouts (6)
. . . and the bearing plane (3) to form a one-plane static pressure gas bearing part (9)
The hemispherical silent pressure gas bearing part α is composed of the jet port (force...) and the bearing spherical surface (4), and the shaft through hole (5)
is the shaft passage part α4 through which the rotating shaft body α described later is inserted.In addition, the shaft passage part θ4 has a gas discharge passage (8a),...
・is open.

A rotating shaft body α2 is inserted through the shaft hole (5) of the main body (1). A hemispherical retaining part α0 with a thick end face is formed at one end of the shaft member, and a mounting screw part αη and a connecting part α barrel extending coaxially thereto are formed at the other end. 0 and the engaging portion (119) are provided with an engaging groove α along the longitudinal direction.

One rotary table (c) is attached to the upper end of the rotating shaft α force mentioned above.
are rotatably fitted. This rotary table (c) is made of a disc-shaped member, and the center part has the above-mentioned retaining part αQ.
A concave spherical secured portion (E) corresponding to the rotary table (E) is provided, and this rotary table (E) is kept υ horizontal by the above-mentioned 1,000-sided static pressure gas bearing portion (9), and rotates. Shaft body (12
They are engaged with each other so as to be able to tilt freely. A driving pin 127) as a locking driver is installed in the locked part (E), and the rotation of the rotating shaft body (L) is carried out via this driving pin (5) and the engagement groove. The signal is transmitted to the rotating table (c).

Furthermore, a hemispherical body (30) is fitted to the lower end of the rotating shaft α. This has a convex hemispherical surface 3υ corresponding to the bearing spherical surface (4), and the roundness of the mounting screw part αη. )C
33, (g), the relative position with respect to the rotating shaft body α0 is adjusted, and the relative position with the hemispherical silent pressure gas bearing portion α0) is also adjusted.

A rotational drive mechanism (to) for rotationally driving the above-mentioned rotating shaft body H is provided below the rotating shaft body H. This is a motor θD supported by supports (to) and (g) attached to the back surface (3) of the main body (1), and a coupling (to ), and the rotating shaft body α is rotated by the rotation of the motor 07).

Next, the operation of this embodiment will be described. First, the gas supply path (
8) Supply compressed gas (air) for the bearings from ..., operate the thousand-sided static pressure gas bearing part (9) and the spherical static pressure gas bearing part α@, and rotate the rotary table (to) and the hemisphere ( :io) is at the specified position. Thereafter, when the motor 07) is driven, the rotary shaft body 0 rotates via the coupling (to), and the rotary table (c) rotates. Set the two static pressure gas bearings (9) and (10) to the rotary table (
2F9 is restrained in the thrust direction and is always kept horizontal by a static pressure gas bearing part (9). When the rotating shaft body α is slightly tilted, it returns to the vertical position due to the imbalance in the pressing force of the static pressure gas bearing portion (9).

Next, another embodiment will be described with reference to FIG. This embodiment differs from the above-described embodiment shown in FIG. 1 only in the configuration of the shaft passage portion, and the other parts are the same, so a description thereof will be omitted. In FIG. 2, a shaft passage portion (411) is formed with a slightly larger diameter than the rotating shaft α2, and has a spout port 4 which spouts out compressed gas.
... is provided, and the radial silent pressure gas bearing part 143
It consists of Effects of the Invention As detailed above, the rotary table device of the present invention uses a thousand-sided static pressure gas bearing section that acts directly on the back surface of the rotary table and a hemispherical spherical static pressure gas bearing section to rotate the table. Since it is configured to hold the table, it requires only half of the conventional spherical bearing that uses almost the entire sphere, making the configuration simple and thin.

Further, since the rotary table and the rotary shaft are engaged with each other at a part of the spherical surface, the rotary table is always kept horizontal, which provides excellent effects.

Furthermore, as in other embodiments, the shaft passage portion is provided with a radial static pressure gas bearing, and the shaft runout accuracy is good for high-speed rotation.

In both embodiments, a hemispherical body is used, but it is needless to say that it does not have to be an exact hemisphere and may be smaller than a hemisphere.

[Brief explanation of drawings]

FIG. 1 is a sectional front view of one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part of another embodiment. (1)...Main body, (2)...Bearing plane, (4)...
・Spherical bearing. (9) Planar static pressure gas bearing part, al... Hemispherical static pressure gas bearing part,

Claims (3)

[Claims] (1) A 1000-sided low-pressure gas bearing with a flat upper end surface as a bearing plane, and 1000-sided low-pressure gas bearing with a part of a concave spherical surface whose central axis is an axis perpendicular to the bearing plane as a bearing spherical surface. consists of a main body having a hemispherical static pressure gas bearing that receives loads in opposite directions and a shaft passage portion consisting of a hole that communicates the two bearings, and a disc-shaped member with a part of a concave spherical surface in the center of the upper surface. a rotary table having a secured portion and having a lower surface facing the bearing plane; a hemispherical body having a convex hemispherical surface corresponding to the bearing spherical surface and facing the bearing spherical surface; A rotary shaft body having a hemispherical engagement portion corresponding to the engaged portion, abutting on the engaged portion, being inserted into the shaft passing portion and fixed to the hemispherical body, and rotating the rotary shaft body. A rotary table device comprising: a rotational drive mechanism; and a retaining drive body that transmits rotation of the rotary shaft body to the rotary table. (2) The rotary table device according to claim 1, wherein the rotary shaft body is fixed to the hemisphere so that its position can be freely adjusted. (3) The rotary table device according to claim 1 or 2, wherein the shaft passage portion includes a radial static pressure gas bearing portion.