JPH04125845A - Turn table - Google Patents

Abstract

PURPOSE:To prevent the inclination of a recording medium with small magnetic attracting force by fitting a member whose friction coefficient with the recording medium is large and which is easily and elastically deformed to the external-side of a recording medium supporting surface by permitting it to slightly protrude from the supporting surface. CONSTITUTION:Urethane rubber 7 is a strip having an internal diameter almost similar to the external surface of a turn table 2 and it is fitted to the external surface of the turn table 2 by adhesive and the like so that it slightly protrudes toward a disk-side from the disk supporting surface 2a by a little amount. Thus, an optical disk which is magnetically attracted to the disk supporting surface 2a-side of the turn table 2 by a permanent magnet 3 is pressed to the disk supporting surface 2a while the protruding part of rubber 7 is deformed. The disk is abutted on the supporting surface 2a and rubber 7 and supported by them. At that time, rubber 7 is partially peeled with a secular change and the flat degree of the external-side of the disk supporting surface 2a is deteriorated even if rubber is adhered to the optical disk, whereby the inclination does not occur in the optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a turntable that replaceably supports and rotates a disk-shaped recording medium.

(Prior Art) Various information recording and reproducing apparatuses have been known that record or reproduce information by rotating a disk-shaped recording medium. Among these devices, one that makes the recording medium replaceable is a turntable that applies frictional force such as spring force or magnetic attraction force between the recording medium and the turntable that supports and rotates the recording medium. There was a device that rotated the recording medium by transmitting the rotational force of the recording medium to the recording medium.

FIG. 2 shows an example of a conventional drive device including a turntable. In the figure, 1 is a disk-shaped recording medium, such as an optical disk, 2 is a turntable, 3 is a permanent magnet,
4 is a disk hub, and 5 is a spindle motor. The optical disc 1 includes a disc hub 4 made of ferromagnetic material at its center. The turntable 2 is equipped with a permanent magnet 3 for magnetically attracting a disk hub 4, and an optical disk 1 is mounted on the annular recording medium (disk) supporting surface 2a.
are supported and fixed in a replaceable manner. Further, the spindle motor 5 rotates the turntable 2 together with the optical disc 1.

When using such a turntable 2 to start rotating the optical disc 1 with a large moment of inertia at high speed, in order to prevent it from slipping on the first disc 1 or the turntable 2, it is necessary to prevent the slippage determined by the start-up acceleration of rotation and the moment of inertia. It is necessary that the frictional force determined by the coefficient of friction between the optical disc 1 and the turntable 2 and the magnetic attraction force be greater than the force.

Here, if the magnetic attraction force is the moment of inertia of the F1 optical disk 1, the friction coefficient is μ, and the rotational acceleration is α (=ω/τ, where ω is the steady rotation speed and τ is the startup time), then the magnetic attraction force is The relationship with the activation condition is expressed by the following equation.

F≧C−J・α/μ (However, C is a constant that depends on the dimensions of the turntable 2) Specifically, for example, the thickness is 1. The tip disk 1, which has a diameter of 130 mm and is made of a 2 mm double-sided glass substrate, is rotated at 240° rpm.
When rotating steadily at 27mm and 32III11
Then, the friction coefficient μ between the disk support surface 2a, which is usually made of a polished stainless steel surface, and the front disk 1 is about 0.14, so in order to achieve steady rotation within the startup time τ-2 seconds, A large magnetic attraction force of 1 kgf or more is required.

However, in order to increase the magnetic NA and attractive force, it is necessary to use an expensive high-performance magnetic material for the permanent magnet 3, and also,
If the magnetic attraction force is increased, the load when unloading the optical disc 1 from the turntable 2 increases, which causes problems such as a decrease in the reliability of the disc loading mechanism. In addition, in optical disks made of plastic substrates, if the magnetic attraction force is too large, the disks will bend, causing distortion in the recording or reproducing light beam, which will degrade the quality of the recorded or reproduced signals.

Figure 3 shows another example of a conventional turntable.
FIG. 5(a) is a perspective view, and FIG. 2(b) is a sectional view taken along the line A-A'. In the figure, 6 is a member having a large coefficient of friction and easily deforming elastically, such as urethane rubber, and is attached to a predetermined position on the disk support surface 2a. According to the above configuration, the coefficient of friction with the optical disc 1 can be increased, and the required magnetic attraction force can be reduced accordingly.

(Problem to be Solved by the Invention) However, in the turntable, the urethane rubber 6 partially deteriorates over time, and this adheres to the surface of the optical disc 1 and the disc support surface 2a, causing the optical disc 1 to tilt. There was a problem with causing this.

The ISO standard for 130 long diameter optical discs stipulates that the inclination of the optical disc with respect to the optical axis of the optical head is 5 mrad or less. Therefore, the perpendicularity of the turntable 2 with respect to the optical axis of the optical head is usually 1 to 5 mrad. It is kept below 2mrad. Therefore, there is a problem in that it is practically difficult to use a member such as urethane rubber, which tends to partially peel off over time, on the disk support surface 2a from the viewpoint of maintaining the inclination of the optical disk.

In view of the above-mentioned conventional problems, the present invention provides a turntable that does not require a large magnetic attraction force, does not cause the recording medium to tilt, and can start rotating a recording medium with a large moment of inertia at high speed. The purpose is to

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a turntable that replaceably supports and rotates a disk-shaped recording medium via a recording medium supporting surface. Alternatively, a turntable is proposed in which a member that has a large friction coefficient with the recording medium and is easily elastically deformed is mounted on the inside so as to slightly protrude toward the recording medium from the recording medium support surface.

(Function) According to the present invention, when the recording medium is mounted, the recording medium is pressed against the recording medium support surface while deforming the protruding portion of the member that has a large friction coefficient with the recording medium and is easily elastically deformed,
It abuts and is supported by the recording medium support surface and the member.

(Embodiment) Fig. 1 shows an embodiment of the turntable of the present invention, in which Fig. 1(a) is a perspective view and Fig. 1(b) is a sectional view taken along line B--B. In the figure, the same components as those of the conventional example are represented by the same reference numerals; 2 is a turntable, 2a is a disk support surface, 3 is a permanent magnet, and 7 is a member that has a large coefficient of friction and is easily elastically deformed, such as urethane rubber. In addition to the urethane rubber 7, synthetic rubbers having similar properties such as silicone rubber, butyl rubber, and nitrile rubber may also be used.

The urethane rubber 7 is generally ring-shaped and has an inner diameter that is almost the same as that of the outer surface of the turntable 2, and has a smaller amount (d in the figure) on the outer surface of the turntable 2 than the disk support surface 2a. It is attached with adhesive or the like so that it protrudes toward the disk side.

According to the above configuration, when the optical disk is mounted, the optical disk (not shown) that is magnetically attracted to the disk support surface 2a side of the turntable 2 by the permanent magnet 3 is attached to the urethane rubber 7.
is pressed against the disk support surface 2a while deforming the protruding portion thereof, and is brought into contact with and supported by the disk support surface 2a and the urethane rubber 7.

At this time, even if the urethane rubber 7 partially peels off due to aging and adheres to the optical disc, the disc support surface 2
Since the flatness of the outside of a is only deteriorated, no tilt occurs in the optical disc. Further, since the contact surface between the urethane rubber 7 and the optical disk has a large coefficient of friction, the frictional force increases accordingly, and it is possible to prevent the optical disk from slipping when starting rotation.

Here, in the case of a 1301-diameter optical disk according to the ISO standard, the disk support area has a diameter of 27.0 mm to 35.0 mm, and the format area starts from the reflective zone diameter of 54.0 mm to 58.0 mm, so the substrate Considering that the diameter of the condensing spot on the surface is about 1 mm, the range in which the urethane rubber 7 can be attached is from 35 mm in diameter to
It becomes 53+*m.

FIG. 4 shows another embodiment of the present invention, and FIG.
is a perspective view, and figure (b) is a sectional view taken along the line C--C.

In the figure, 8 is a member that has a large coefficient of friction and is easily elastically deformed;
For example, it is made of urethane rubber, and has a generally annular shape as a whole and has an outer diameter that is approximately the same as the inner surface of the turntable 2.

The urethane rubber 8 is attached to the inner surface of the turntable 2 with an adhesive or the like so that it protrudes toward the disk by a slight amount (d in the figure) than the disk support surface 2a.
As in the case of the embodiment shown in FIG. 1, when the optical disk is mounted, the protruding portion is deformed and the optical disk and the disk supporting surface 2a are
The optical disc is brought into contact with and supported by the optical disc, and the frictional force between the disc and the optical disc is increased.

Here, in the case of an ISO standard 130mm diameter optical disc,
Since the area of the disc hub is 0+am to 25.0mm, the range in which the urethane rubber 8 can be installed is 2511+mm in diameter.
+a~27 +*si.

In the above embodiment, a ring-shaped member was used, but within the above-mentioned range, piecemeal members may be attached at predetermined intervals, and the contact surface with the optical disc may be serrated or triangularly wave-shaped. It goes without saying that similar functions and effects can be obtained by using a ring-shaped member having a shape.

(Effects of the Invention) As explained above, according to the present invention, in a turntable that replaceably supports and rotates a disk-shaped recording medium via a recording medium support surface, Because the member, which has a large coefficient of friction with the recording medium and is easily deformed elastically, is attached so as to slightly protrude toward the recording medium from the recording medium support surface, the coefficient of friction with the recording medium is large when the recording medium is mounted. In addition, the protruding portion of the elastically deformable member is deformed and pressed against the recording medium support surface, and comes into contact with and is supported by the recording medium support surface and the member. Even if it partially peels off and adheres to the recording medium, the flatness of the outside or inside of the disk support surface will only deteriorate, and the recording medium will not be tilted, and moreover, the contact surface between the member and the recording medium will deteriorate. has a large coefficient of friction and a correspondingly large frictional force, making it possible to start a recording medium with a large moment of inertia at high speed even with a small magnetic attraction force.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are diagrams showing one embodiment of the turntable of the present invention, FIG. 2 is a configuration diagram showing an example of a drive device including a conventional turntable, and FIGS. 3(a) and (b). )
is a diagram showing another example of a conventional turntable, and FIG.
) (b) is a diagram showing another actual version of the turntable of the present invention. 2... Turntable, 2a... Disk support surface, 3... Permanent magnet, 7° 8... Urethane rubber. Patent applicant Nippon Telegraph and Telephone Corporation Representative Patent attorney Yoshi Yoshi 1) Takashi Sei (a) Figure 1 showing one embodiment of the turn table of the present invention Figure 6 Urethane rubber 6 Urethane rubber (a) Other than conventional tongue table Figure 3 showing an example

Claims (1)

[Scope of Claims] A turntable that supports and rotates a disk-shaped recording medium in an exchangeable manner through a recording medium support surface, wherein the outside or inside of the recording medium support surface has a large coefficient of friction with the recording medium and is elastic. A turntable characterized in that a deformable member is attached so as to slightly protrude toward the recording medium from the recording medium supporting surface.