JPS63183637A - Optical disk - Google Patents

Abstract

PURPOSE:To shorten the time for starting rotation by adhering members having a large coefft. of friction to surfaces to contact a turn table. CONSTITUTION:The members 13 consisting of polycarbonate or synthetic rubber material, etc., having the large coefft. of friction with the turn table 9, center hubs 11-a, 11-b of which are electrically turned, are mounted to the surfaces of the disks 8-a, 8-b supported by the table 9, which surfaces contact the table 9. Idling of the disk at the time of starting the turning is, therefore, suppressed and the time for starting the rotation is shortened.

Description

[Detailed description of the invention] Technical fields> The present invention relates to an optical disc with a novel structure.

<Prior Art> In recent years, so-called optical discs have been developed in which recording, reproduction, or erasing is performed on a disc-shaped recording medium using an optical head using a laser or the like. These optical discs are made of glass,
Recording and reproducing information on substrates such as plastic and metal,
An erasable medium is provided, and recording areas are provided concentrically or spirally.

Here, the interval between the spiral or concentric recording areas (tracks) is extremely small, about 1 to 2 μm. However, when a disk is normally rotated by a motor or the like, mechanical errors cause the disk to run out of center, making it impossible to accurately track tracks when recording, reproducing, or erasing with light irradiated from an optical head. For this reason, in a drive system that drives an optical disk, the optical head uses some method to detect the amount of deviation of the light beam spot from the track.
Usually, a servo system is provided that can change the position of a light spot used for recording, reproducing, and erasing to accurately follow a track portion.

However, the capabilities of this servo system are not perfect and have limits, so it is extremely important to manage the amount of core runout within limits to produce optical disks.

For this reason, a disk having a structure as shown in FIG. 2 has conventionally been used as an example.

That is, a member 4 called a center hub is attached to the center of the optical disk 1, and a shaft 3 at the center of rotation of the motor is fitted into a hole at the center of the center hub 4 to serve as a reference for the center of rotation. A plate 5 made of ferromagnetic material such as iron is attached to the center hub 4, and this plate 5 is attached to the turntable 2.
It is attracted by the magnet 7 provided in the.

In this case, the center hub 4 is provided so that when the disk is rotated as shown in FIG. 2, the center of the track on which information is recorded, reproduced, and erased coincides with the center of the center hub.

By doing so, dimensional errors such as eccentricity that occur during the manufacturing process of the disk can be extremely reduced by providing the center hub. Also, at this time, the turntable 2, which is the rotating part of the motor, supports the optical disc 1 by the clamp area 6.

By doing so, the surface runout of the disk l is not increased.

Now, one of the performance requirements generally required for such an optical disk device is to shorten the start-up time for disk rotation. This is useful when optical discs are used frequently, or for a so-called jukebox type device that stores many optical discs and automatically selects and mounts one optical disc for recording, playback, and erasing. This is especially important.

However, in the case of the configuration shown in Fig. 2, if an attempt is made to shorten the starting time of rotation, slippage will occur at the contact portion 6 between the disc 1 and the turntable 2 at the time of startup, causing the turntable 2 and the disc 1 to spin idly. A situation such as putting it away may occur.

If, for example, glass is used as the material for the disk I, its weight is approximately twice that of plastic, and therefore approximately two to three times as much torque is required at the time of starting rotation. However, in the case of glass, the coefficient of friction on the surface is smaller than that of plastic or the like. For example, in the case of glass-metal, the coefficient of static friction on the surface is about 0.1 to 0.2, which is about half of that of plastic-metal, which is 0.3 to 0.5.
There is only the size of For this reason, when glass is used as the disk substrate material, the start-up time is several times longer than when plastic is used, and it is necessary to slowly increase the rotation speed to prevent the system from idling. It was causing a hindrance.

<Object of the Invention> An object of the present invention is to provide an optical disc having a structure in which the disc does not spin idly even if the rotation startup time is shortened.

<Embodiment> Hereinafter, one embodiment of the optical disc of the present invention will be described in detail with reference to FIG.

In FIG. 1, optical discs 8 a and 8 b are provided with center hubs lla and llb, respectively, which are supported by a turntable 9. As shown in FIG.

At this time, the area on the surface of the disc 8a where the turntable 9 contacts the optical disc 8a is made of a material 13a having a sufficiently large coefficient of friction with respect to the material constituting the turntable 9.
is glued. Examples of this material include synthetic resin materials such as polycarbonate, synthetic rubber, polyethylene, and polyimide. As mentioned above, these resins have a larger coefficient of friction than glass, which is the disk substrate material, and can accordingly increase the torque at the time of rotation start-up and shorten the start-up time. Also, if this material 13 is glued to the disc 8, the height from the turntable 9 will increase, and the height of the medium surface on which recording and playback of the disc will be different. 0.
By setting the thickness to about 1 mm, recording, reproduction, and erasing can be performed virtually without problems. Because optical head recording.

This is because the movable range of the objective lens that performs reproduction and erasing is approximately several hundred μm, so a range of about 0.1 mm is sufficient to fall within that range.

<Effects of the Invention> According to the present invention as described above, by configuring the disk in which the contact portion with the turntable is made of a material having a sufficiently large coefficient of friction compared to the turntable, the rotation startup time of the optical disk can be shortened. It is possible to speed up system operation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of an optical disc according to the present invention, and FIG. 2 is a sectional view of a conventional optical disc. In the figure 1a, 1b, 8a, 8b: Optical disk board 2.9 = turntable 3.10: Motor rotation shaft 4a, 4b, 11a, l Ib: Center hub 5.12
Nibrate 6: Contact part 7.14: Magnet agent Patent attorney Itaru Sugiyama Kazuki (and 1 other person) Engraving of drawings (no changes to 2J) Figure 181 Figure 2 Procedural amendment (crab. April 1, 1988) Day 1, Indication of the case Patent application 1982-14453 2. Name of the invention Optical disk 3. Person making the amendment Relationship to the case Patent applicant address !545 22-22 Nagaike-cho, Abeno-ku, Osaka-shi
Name (504) Nyap Co., Ltd. Representative Haruo Tsuji 4, Agent Address 6545 22-22 Nagaike-cho, Abeno-ku, Osaka-shi
(No change within Sharp Corporation).

Claims (1)

[Claims] 1. In an optical disc in which information is recorded and reproduced by rotating a disk-shaped recording medium, the contact surface of the substrate with the turntable has a sufficiently large coefficient of friction with respect to the material of the turntable. An optical disc characterized by being equipped with a material.