JPS63261571A - Disk/turn table - Google Patents

Abstract

PURPOSE:To actuate at high speed the disk having large moment of inertia by providing the member easy to be subjected to elastic deformation in a rotary shaft direction and having a high friction coefft. in the space with a recording medium inside the groove of the abutting face of the recording medium of a turn table so that the upper face becomes higher than the abutting face. CONSTITUTION:A notch shaped groove 2a is formed in the circumferential direction with equal interval on the disk abutting face of a turn table 2 and an urethane rubber piece 8 is fitted into this groove 2a. The thickness of the urethane rubber piece 8 is formed so as to attain to about 30mum projecting amt. delta from the abutting face 2b of the turn table 2. In the case of the disk being fixed, the urethane rubber piece 8 is completely deformed up to the abutting face 2b, so the disk is supported by the abutting face 2b and yet by the fixture of the disk to the abutting face 2b, the friction coefft. becomes larger because of the respective contact of the abutting face 2b and disk, and urethane rubber piece 8 and disk. The high speed actuation of the disk having large moment of inertia is thus enabled.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a turntable that supports and rotates a recording medium in a drive device for a disk-shaped recording medium that is driven when recording and reproducing information. Regarding.

<Prior art and problems> Disc-shaped information recording media are rotated at high speed for recording and reproduction. During this rotation, the recording medium, such as an optical disc, is placed on a turntable. mounted and fixed. This type of turntable is made of metal such as stainless steel and has a structure as shown in FIG. In Fig. 4, 1 is an optical disk, 2 is a turntable, 3 is a permanent magnet for attracting and fixing the optical disk, 4 is a disk drive that is a part of the optical disk and has a ferromagnetic material, and 5 is a spindle motor. .

When starting an optical disc 1 with a large moment of inertia at high speed using such a turntable 2, in order to prevent the optical disc 1 from slipping on the turntable 2, the optical disc 1 must be firmly fixed on the turntable 2. It is necessary to That is, a transmission torque is required between the optical disk abutting surface of the turntable 2 and the optical disk 1 that can counter the rising acceleration.

Here, considering the transmission torque, the transmission torque from the turntable 2 of a certain size to the optical disk 1 is
The larger the adsorption force F is, the thicker it is (and the larger the j@friction coefficient μ of the optical disk abutting surface of the turntable 2 is, the greater the adsorption force F and startup conditions are. The relationship is expressed by the following equation.

Here, F is the adsorption force, C is a constant depending on the turntable dimensions, J is the moment of inertia of the optical disk, μ is the friction coefficient, R is the steady rotation speed, and τ is the starting time.

In other words, if the friction coefficient μ is large or the startup time τ is long, the adsorption force F may be small, but in the opposite case, the adsorption force F will be large, and if the moment of inertia J or steady rotational speed is large, a large adsorption force F is required. becomes.

FIG. 6 shows the relationship between the startup time r and the adsorption force F to prevent slippage when the glass disk is rotated steadily up to 240 Orpm. As can be seen from the figure, the shorter the rise to steady rotation, the more
The adsorption force increases at an accelerating rate. In this case, the coefficient of friction μ between the glass disk and the polished stainless steel surface that is the contact surface of the turntable is about 0.14, so in order to achieve steady rotation for 2 seconds as shown in the figure, 1 kgf is required.
A greater adsorption force is required.

However, when increasing the attractive force F, increasing the attractive force of the permanent magnet 3 involves the problem that an expensive high-performance permanent magnet 3 is required, and at the same time, the load when unloading the optical disk is large. This has the disadvantage of lowering the reliability of the mechanism. That is, there is a problem in increasing the attractive force of the permanent magnet 3 to increase the attractive force F for high-speed startup.

On the other hand, for high-speed startup, it is also possible to increase the friction coefficient without increasing the attraction force of the permanent magnet 3, for example, by covering the contact surface of the turntable with a high II [WA material such as urethane rubber]. However, there is another problem.In other words, it is well known that in optical recording drive devices, if the relative tilt between the optical disk and the head exceeds 6 m rad, the recording and reproducing characteristics will deteriorate significantly. Therefore, in addition to strictly controlling the warping of the optical disk, the abutment surface of the turntable for mounting the optical disk has a highly accurate surface angle (usually 1 m rad ~
2 mrad or less) is required. Therefore, a precisely polished metal surface is conventionally used for the highly accurate contact surface of the turntable. For this reason, it has been extremely difficult in practice to use a contact surface of a turntable whose surface is coated with urethane rubber or the like to increase the coefficient of friction μ.

Figure 5 shows another example of a conventional turntable.
At least one anti-rotation pin 6 supported by a weak spring (not shown) is disposed inside the turntable 2, and a slip prevention hole 7 that can be fitted with the anti-slip pin 6 is provided at a corresponding position on the disc hub 4. It is a structure. Due to this structure, when the disk slips and the anti-rotation pin 6 hits the anti-slip hole 7, the anti-rotation pin 6 slightly protrudes due to the spring and fits into the anti-slip hole 7.

However, such a mechanism has the drawback that the spring must be designed in consideration of the unavoidable slippage of the disk and the dynamic characteristics of the detent pin 6, making the structure of the turntable complicated.

Therefore, in view of the above-mentioned problems, the present invention has been developed to reduce the moment of inertia without increasing the attraction force of the permanent magnet, without attaching a high friction coefficient material to the entire contact surface (and without creating a complicated structure). To provide a low-priced disc turntable which can start up a large disc at high speed, combines high precision and simplicity.

Means for Solving the Problems〉 The present invention achieves the above-mentioned object by providing a drive device for a disk-shaped recording medium that is driven when recording and reproducing information. In a turntable that supports and rotates a medium, a groove is provided in a part of the recording medium abutting surface of the turntable, and a groove is formed in the groove that is elastically deformed in the direction of the rotation axis and has a coefficient of friction with the recording medium. The present invention is characterized in that it includes a tall member such that its upper surface is higher than the abutment surface.

Since the turntable surface according to the present invention has such a structure, when the disk is loaded, the high friction material is deformed in the axial direction by the attraction force of the permanent magnet, and the disk surface is finished with high precision. Since the turntable is supported by the metal surface of the turntable, the tilt accuracy with respect to the rotation axis is not impaired. At the same time, it also has the effect of reducing the impact force applied to the disc when the disc is loaded. Also, high Wji
The friction in the area corresponding to the friction material increases the torque that can be transmitted on the turntable surface, making it possible to start up a disk with a large moment of inertia at high speed. Furthermore, such a turntable has a simple structure and can be provided at a low cost.

EMBODIMENTS> The present invention will now be described in detail with reference to FIGS. 1 to 3. Note that the same parts as in FIG. 4 are given the same reference numerals.

In Figure 1, 2 is a turntable, 3 is a permanent magnet,
8 is a urethane rubber piece. In addition to metal materials, the turntable 2 may also be made of highly rigid engineering plastics, such as polyacetal copolymer. Further, since the urethane rubber piece 8 is a high friction material, synthetic rubbers such as silicone rubber, butyl rubber, and nitrile rubber having similar properties can be used.

Notch-shaped grooves 2a are formed on the disc contacting surface of the turntable 2 at equal intervals in the circumferential direction (at four locations in the figure), and urethane rubber pieces 8 are fitted into the grooves 2a. and,
The thickness of the urethane rubber piece 8 is formed so that it protrudes from the contact surface 2b of the turntable 2 by an amount δ of about 30 μm. In this embodiment, when the disk is fixed once with a suction force of about 200 gf or more, the urethane rubber piece 8 completely deforms to the contact surface 2b, so the disk is supported by the contact surface 2b, and the urethane rubber piece 8 deforms completely to the contact surface 2b. Since the rubber piece 8 is provided, the disk does not become tilted.

Moreover, by fixing the disk to this contact surface 2b, the contact surface 2b and the disk, the urethane rubber piece 8 and the disk,
The coefficient of friction increases with each contact.

Fig. 2 shows another embodiment in which a groove 2a is not provided by cutting out the contact surface 2b of the turntable 2, but a hole-shaped groove is provided on the contact surface 2b, and a piece of urethane rubber is inserted into the hole groove. 8 may be fitted. In this case as well, the length of the urethane rubber piece 8 protruding from the contact surface 2b is such that the thickness can be changed by a slight pressing force of about 30 μm.

FIG. 3 shows the effect of the embodiment of FIG.

In FIG. 3, 10 is the measurement result of the friction characteristics of the glass disk in the conventional turntable shown in FIG.
The measurement results of the friction characteristics of the turntable of the example shown in the figure are shown.

From the figure, the coefficient of friction in the turntable of the embodiment shown in Fig. 1 is approximately 5 times that of 0.65, and as can be seen from Fig. 6,
Sufficient high-speed startup is possible even with an adsorption force of several hundred gf.

<Effects of the Invention> As explained above, the turntable according to the present invention has a simple structure and can start a disk with a large moment of inertia at high speed even with a small disk fixing force. Furthermore, there is a practical advantage that the turntable surface does not tilt due to the provision of the high-friction material. Furthermore, since the shock applied to the disc when loading the disc is alleviated, it has the effect of improving the durability and reliability of the disc.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a perspective view and an A-A' sectional view of an embodiment of the turntable according to the present invention, and FIG.
(bl is a perspective view and an A-A' sectional view of another embodiment,
The figure is a characteristic diagram showing the effect of the turntable shown in Fig. 1, Fig. 4 is a configuration diagram of a conventional example, Fig. 5 is an exploded perspective view of the conventional example, and Fig. 6 shows the adsorption force and force to prevent slipping. FIG. 3 is a characteristic diagram of disk startup time. In the figure: Disk 1 2 Turntable, 3 Permanent magnet, 4 Disc hub, 5 Spindle motor, 6 Stopping pin, 7 Slip prevention hole, 8... Urethane rubber piece, 10... Conventional turntable friction characteristics, 11...
- Turntable friction characteristics of this example.

Claims (1)

[Claims] Among drive devices for disk-shaped recording media that are driven when recording and reproducing information, in a turntable that supports and rotates the recording medium during recording and reproduction, the recording medium contact surface of the turntable A groove is provided in a part of the groove, and a member that is easily deformed elastically in the direction of the rotational axis and has a high coefficient of friction with the recording medium is provided in the groove so that the upper surface thereof is higher than the contact surface. Disc turntable.