JPS6310505B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotary drive device for rotationally driving a disk-shaped recording medium (hereinafter referred to as a disk), and an adjusting means for aligning the center of the disk with the center of rotation. It has the following characteristics.

Conventional Structure and Problems Conventionally, when a disk such as a disc-shaped recording master without a center hole is centered on a turntable, it has been done by mechanically fitting the outer periphery of the disk and the turntable. According to this method, since the outer diameter of the disk is large, it is very difficult to control the variation in diameter. Due to the looseness of the fit, accurate centering was not possible, and vibrations were occurring due to imbalance.

OBJECTS OF THE INVENTION The present invention provides a disk rotation drive device that eliminates the above-mentioned drawbacks and can easily align the center of the disk with the rotation center of the turntable even if the disk does not have a center hole or recording groove. This is what we provide.

Structure of the Invention The present invention detects the position of the outer periphery of the disk using a detection means such as a laser and a detector, based on the position of the outer periphery of the disk when the center of the disk coincides with the center of the turntable, and detects the position on the turntable. The system is configured to detect the amount of eccentricity between the center of the placed disk and the center of rotation of the turntable, and adjust the amount of movement of the positioning member that comes into contact with the outer peripheral surface of the disk according to the detected output, and promptly, It is constructed so that the centers of the disc and turntable are aligned.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows a schematic diagram of an embodiment of a disk rotary drive device according to the present invention. A disk 1 without a center hole is suctioned onto a turntable 2 by vacuum suction means. 3 is a bearing, and an aerostatic bearing is used here. 4 is a motor for driving the turntable 2, and 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 sliding section 8 that supports the disk pressing section 7 so as to be linearly movable in the radial direction of the disk 1, and the disk pressing section. It consists of a motor 9 that moves the motor 7 in a straight line. Further, as a means for detecting the amount of eccentricity of the disk 1, a Reger 10 is provided.
The center of the beam 11 is adjusted so that when the center of the turntable 2 and the center of the disk 1 coincide, it becomes a tangent to the outer periphery of the disk. 12 is a detector that converts the beam 11 into an electrical signal.

During adjustment, the disk 1 is lightly attracted to the turntable 2 by the vacuum suction means, so that it can be moved on the turntable by applying an external force of a predetermined amount or more in the radial direction from the outer periphery.

FIG. 2 is a diagram showing how the eccentricity of the disk 1 disappears.The center of the disk 1 is Q, the rotation center of the disk 1 is O, and the roller 7 gradually moves toward the O direction. It's moving.

Here, if the disk 1 is rotating eccentrically by δ as shown in FIG. 2A, then when the roller 7 gradually moves and reaches the position shown in FIG. 2A,
It begins to make contact with the outer periphery of disk 1. When the disk 1 rotates once around O as shown in Figures B and C and reaches position D, the roller 7 is closer to the center of rotation O than at position A. Therefore, the roller 7 contacts the disk 1 before the center Q of the disk comes on the line connecting the rotation center O and the center of the roller 7.

At this time, a force F is generated between the rotational force of the disk 1 and the roller 7, and the force F from the disk center Q is represented by component forces F ₁ and F ₂ directed toward the rotation center O. This means that the disk center Q approaches the rotation center O by a force _F1 . By repeating this operation several times, the disk center Q and rotation center O can be made to coincide.

Furthermore, when the output signal of the detector 12 is eccentric between the center of the disk 1 and the rotation center of the turntable 2, the beam 11 becomes an intensity-modulated signal as shown in FIG. When the eccentricity disappears, the signal becomes constant as shown in Figure 3 (b). At this time, the motor 9 that moves the pressing part 7 is reversed, the roller is separated from the disk, and the suction force of the suction means is increased to fix the disk to the turntable. An embodiment configured to automatically perform this series of operations is shown in FIG. 4, and its operation waveforms are shown in FIG. The amount of eccentricity of the disk 1 is detected by the detector 12, and its detection output (Figure 5 A)
is amplified by the AC amplifier 13 (Fig. 5 B), full-wave rectified by the absolute value circuit 14 (Fig. 5 C), and smoothed by the smoothing circuit 15.
to reduce ripple (Fig. 5 D).

On the other hand, the reference voltage generation circuit 16 generates a voltage corresponding to the permissible eccentricity of the disk 1, and this voltage and the output voltage from the smoothing circuit 15 (FIG. 5D)
When the output voltage e of the smoothing circuit 15 (FIG. 5 D) is larger than the reference voltage, the motor control circuit 18 causes the motor 9 to gradually move the roller 7 toward the center of the disk 1. Continue to send current as it moves. Also,
When the voltage shown in FIG. 5D becomes equal to the reference voltage, the motor control circuit 18 sends a current to the motor 9 so that the roller 7 moves away from the disk 1.

Effects of the Invention As described above, according to the present invention, even a disk without a center hole can be easily placed on a turntable with an eccentricity of several microns, and since the eccentricity is significantly reduced, unbalance can be avoided. This also eliminates the vibration caused by

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of a disk rotation drive device according to the present invention, Fig. 2 is an explanatory view showing how the eccentricity between the disk and turntable is eliminated by the present invention, and Fig. 3 is an eccentric amount detection FIG. 4 is a block diagram showing an embodiment of the present invention, and FIG. 5 is a waveform diagram explaining the same operation. 1...disc, 2...turntable, 3...
... Bearing, 4, 9 ... Motor, 5 ... Vacuum tube, 6 ... Recording master positioning section, 7 ... Disk pressing section, 8 ... Slide section, 10 ... Laser,
11... Beam, 12... Daytector.

Claims (1)

[Claims] 1. A turntable on which a disc-shaped recording medium is placed movably in the radial direction, and an outer periphery of the disc-shaped recording medium when the center of the disc-shaped recording medium and the center of the turntable coincide. a 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 by detecting a change in the position of the outer periphery of the disc-shaped recording medium with reference to the position; recording medium positioning means that is movable toward and away from the outer peripheral surface of the disc-shaped recording medium on the table and movable in the diametrical direction of the turntable; A rotational drive device for a disc-shaped recording medium, comprising a drive means for moving the recording medium positioning means so as to align with the center of a table.