JPH051550B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a rotational drive device for a device that records signals on a disc-shaped recording medium (hereinafter referred to as a "disk") in a very clean room. be.

BACKGROUND ART A conventional rotary drive device will be explained using FIG. 6. A disk 1 without a center hole is suctioned by vacuum suction means on a turntable 2. 3
is a bearing, and here an aerostatic bearing is used. 4 is a motor for driving the turntable 2;
5 is a vacuum tube connected to the vacuum suction means. The positioning means 6 includes a disk pressing section 7 whose portion that contacts the disk 1 is constituted by a roller.
, a linear drive section 8 that linearly drives the disk pressing section 7 in the radial direction of the disk 1, and a motor 9 that applies a linear driving force to the disk pressing section 7. Further, a laser device 10 is provided as a means for detecting the amount of eccentricity of the disk 1, and the center of the beam 11 of the laser device 10 is determined when the rotation axis of the turntable 2 and the center of the disk 1 coincide. It is adjusted to be tangent to the outer circumference. 12 is a detector that converts the beam 11 into an electrical signal. This is described in the specification and drawings attached to the application for Japanese Patent Application No. 172705/1983 (Japanese Patent Application No. 010505/1983).

Problems to be Solved by the Invention According to such a conventional configuration, as shown in FIG.
When the stationary rollers of 1 come into contact with each other and the rollers start to rotate, the rollers and the disk slip, causing the outer periphery of the disk 1 to slip. Therefore, the chipping powder 13 lowers the cleanliness inside the clean room, causing dropouts in recorded signals. It also caused damage to disk 1. The present invention solves the above-mentioned conventional problems, and eliminates slippage between the roller and the rotating disk.
It is an object of the present invention to provide a rotational drive device for a disc-shaped recording medium that can prevent eccentricity of the disc.

Means for Solving the Problems In order to solve the above-mentioned problems, a rotational drive device for a disc-shaped recording medium according to the present invention includes a turntable on which a disc-shaped recording medium is movably placed, and a turntable on which the disc-shaped recording medium is movably mounted. eccentricity detection means that generates an output according to the eccentricity with respect to the rotation center of the turntable; and an eccentricity detection means that is movable relative to the outer circumference of the disc-shaped recording medium on the turntable in a diametrical direction of the turntable so as to be able to come into contact with and leave the outer circumference of the disc-shaped recording medium on the turntable. a recording medium positioning means whose contact portion with the disc-shaped recording medium is constituted by a roller; and a driving means for relatively moving the recording medium positioning means and the turntable in accordance with the output of the eccentricity detection means. and a roller rotation drive means for rotationally driving the roller so that the outer circumferential speed of the disc-shaped recording medium and the outer circumferential speed of the roller are the same.

Effect According to the above configuration, since the roller is rotationally driven in advance so that the circumferential speed of the outer periphery of the rotating disk-shaped recording medium is the same as the circumferential speed of the outer periphery of the roller, the roller and the disk-shaped recording medium Even if they come into contact with each other, it will be a rolling contact, and the disc-shaped recording medium will not be scraped and powder will not come out, and the disc-shaped recording medium will not be damaged.

Embodiment Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 5.

FIG. 1 is a perspective view of a rotational drive device for a disc-shaped recording medium according to an embodiment of the present invention, in which a disc 21 without a center hole is suctioned onto a turntable 22 by vacuum suction means. 23 is a bearing, and an aerostatic bearing is used here. 24 is a motor for driving the turntable 22, and 25 is a vacuum tube connected to the vacuum suction means. The positioning means 26 includes a roller 27 that contacts the disk 21.
, a bearing 28 that supports it, and a motor 30 that provides rotational force to the roller 27 via a belt 29.
, a guide 30 that supports the bearing 28 so as to be movable in the radial direction of the disk 21, a linear drive section 31 that transmits linear drive to the guide 30, and a motor 32 that provides driving force to the linear drive section 31. There is. Further, a laser device 33 is provided as a means for detecting the amount of eccentricity of the disk 21, and the center of the beam 34 is set on the turntable 2.
The center of the disk 21 is adjusted so that when the center of the disk 21 coincides with the center of the disk 21, it becomes a tangent to the outer periphery of the disk 21. 35 is a detector that converts the beam 34 into an electrical signal.

During adjustment, the disk 21 is lightly attracted to the turntable 22 by the vacuum suction means, so that it can be moved on the turntable 22 by applying an external force of a predetermined amount or more in the radial direction from the outer periphery.

Figure 2 shows how the eccentricity of the disk 21 disappears.The center of the disk 21 is Q, the rotation center of the disk 21 is O, and the roller 2
7 is gradually moving in the direction of O. At this time, the roller 27 is rotating in a direction opposite to the rotational direction of the disk 21 so that the circumferential speed of the roller 27 and the circumferential speed of the disk 21 are approximately the same. Here, it is assumed that the disk 21 is rotating eccentrically by δ as shown in FIG. 2a. The roller 27 gradually moves, and when it reaches the position shown in FIG. Then, the disk 21 moves around O by 1 as shown in Fig. 2b and c.
When the roller 27 rotates to the position shown in FIG. 2 d, it is closer to the center of rotation O than in FIG. 2 a. Therefore, the center Q of the disk 21 is the rotation center O.
The roller 27 rolls into contact with the disk 21 without slipping. At this time, a force F is generated between the disk 21 and the roller 27, and this force F is represented by a component force F ₁ directed from the disk center Q toward the rotation center O and a component force F ₂ perpendicular to the component force F 1 . This means that the disk center Q approaches O during rotation by a force _F1 . By repeating this action,
The disk center Q and rotation center O can be made to coincide.

Furthermore, when the output signal of the detector 35 is eccentric between the center of the disk 21 and the rotation center of the turntable 22, the beam 34 becomes an intensity-modulated signal as shown in FIG. 3a. When the eccentricity disappears, a constant signal as shown in FIG. 3b is obtained.
At this time, the motor 32 that is moving the roller 27 is reversed, and the suction force of the suction means is increased to fix the disk 21 to the turntable 22.

FIG. 4 is a circuit block diagram of a rotational drive device for a disc-shaped recording medium according to an embodiment of the present invention, and the series of operations described above is automatically performed by this circuit.
The amount of eccentricity of the disk 21 is detected by the detector 35, and the detection output shown in FIG. 5a is sent to the AC amplifier 3.
6, the output shown in FIG. 5b is full-wave rectified in an absolute value circuit 37, and the output shown in FIG. 5c is subjected to ripple reduction in a smoothing circuit 38 to obtain the waveform shown in FIG. 5d.

On the other hand, the reference voltage generation circuit 39 generates a voltage corresponding to the allowable eccentricity of the disk 21, and the comparator 39 compares this voltage with the output voltage from the smoothing circuit 38, and the output voltage e of the smoothing circuit 38 is set to the reference voltage. When it is larger, the motor control circuit 40 continues to send current to the motor 32 so that the roller 27 gradually moves toward the center of the disk 21. When the voltage e becomes equal to the reference voltage, the motor control circuit 40 sends a current to the motor 32 so that the roller 27 moves away from the disk 21, and at the same time, the motor 30 that is rotating the roller 27 is turned on. make it stop.

As another example, the same result can be obtained by moving the rotary drive shaft of the turntable 22 in a radial direction toward and away from the positioning means instead of linearly driving the positioning means 26.

Effects of the Invention As described above, according to the present invention, it is possible to record a disc-shaped recording medium without a center hole without generating scrap powder due to contact between a roller and a disc-shaped recording medium, and without lowering the cleanliness of the apparatus. Even a medium can be automatically placed on a turntable with an eccentricity of several microns.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a rotary drive device according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the process of eliminating eccentricity between the disk and turntable, and Fig. 3 is a waveform of the output signal of the eccentricity amount detector. 4 is a circuit block diagram of a rotary drive device according to an embodiment of the present invention, FIG. 5 is a signal waveform diagram of each part of the circuit shown in FIG. 4, and FIG. 6 is a perspective view of a conventional rotary drive device. 7th
The figure is an explanatory diagram of a state in which a disk and a roller are in contact with each other in the rotary drive device. 21...disc, 22...turntable,
26... Positioning means, 27... Roller, 29
... Belt, 30 ... Motor, 31 ... Linear drive unit, 32 ... Motor, 33 ... Laser device, 35 ... Detector.

Claims (1)

[Claims] 1. A turntable on which a disc-shaped recording medium is movably mounted, an eccentricity detection means for generating an output according to an eccentricity of the disc-shaped recording medium with respect to the rotation center of the turntable, and a recording medium positioning means that is movable relative to the diametrical direction of the turntable so as to be able to move toward and away from the outer periphery of the disc-shaped recording medium, and whose contact portion with the disc-shaped recording medium is constituted by a roller; and the eccentricity detection means. drive means for relatively moving the recording medium positioning means and the turntable in accordance with the output of A rotational drive device for a disc-shaped recording medium, comprising a roller rotation drive means for rotationally driving.