JPH04307440A - Optical disk - Google Patents

Abstract

PURPOSE:To decrease the fluctuation in the offset quantity of the servo control system of an optical pickup device and the influence of crosstalks by suppressing the deformation of the optical disk. CONSTITUTION:The recording surface 1a of a substrate 1 and the surface 1b to be heated by an optical disk driving device are thermally coupled by a heat conductive member 20. Since the heat quantity of the surface 1b is transmitted via the heat conductive member 1b to the recording surface 1a and, therefore, the temp. difference on both surfaces of the substrate 1 is decreased and the deformation of the substrate 1 is suppressed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc that can reduce deformation of a recording surface caused by an external heat source.

0002

2. Description of the Related Art As shown in FIG. 4, an optical disk used as a data recording medium has a substrate 1 made of a plate made of a transparent material formed into a disc shape. The layers 2 are laminated, and a hub member 4 made of a magnetic material is adhesively fixed to a hole 3 in the center of the layer 2 to be connected to a spindle motor (described later) of an optical disk drive.

FIG. 5 shows an example of an optical disk drive device for driving this optical disk.

In the figure, a shaft 7 of a spindle motor 6
is provided with a turntable 8 for fixing the hub member 4 of the optical disk, and this turntable 8 is provided with a magnetic circuit (not shown) for magnetically coupling the hub member 4. There is.

The optical pickup device 9 records and reproduces data on recording tracks (not shown) formed on the recording layer 2 of the optical disc, and the seek mechanism 10 moves the optical pickup device 9 in the radial direction of the optical disc. It is for reciprocating drive.

[0006]

[Problems to be Solved by the Invention] Such conventional devices have the following disadvantages.

That is, heat sources such as the optical pickup device 9 and the seek mechanism 10 are located on the surface 1b of the substrate 1 opposite to the recording surface 1a on which the recording layer 2 is formed, and are heated by these heat sources. , the temperature of the surface 1b is the recording surface 1a
temperature is higher than that of

Therefore, the amount of thermal expansion of the surface 1b of the optical disk becomes larger than the amount of thermal expansion of the recording surface 1a, resulting in a situation where the substrate 1 is deformed as shown in FIG.

[0009] Furthermore, in a double-sided recordable optical disc, two
Two optical disk plates are bonded together with a spacer interposed therebetween. In this case as well, since the heat source is located only on one of the two optical disk plates on which data is recorded/reproduced by the optical pickup device, the optical disk may be deformed as shown in FIG. 7.

As described above, when an optical disk is deformed, the amount of offset in the servo control system for accurately positioning the laser beam of the optical pickup device on the recording surface changes, or the laser beam simultaneously hits adjacent recording tracks. irradiation, causing inconveniences such as crosstalk.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the disadvantages of the conventional apparatus and to provide an optical disc that can suppress the amount of deformation.

0012

[Means for Solving the Problems] The present invention provides a substrate that is more thermally conductive than the substrate and connects the other surface of the substrate and the surface on which the optical recording medium is laminated at a portion that avoids the area where the optical recording medium is disposed. A heat transfer member made of a material with a high heat exchange rate is provided. Moreover, a non-magnetic material is used as the heat transfer member.

Furthermore, two sets of spacers for maintaining the distance between the two optical disk plates are made of a material having higher thermal conductivity than the substrate.

[0014]

[Operation] Therefore, the amount of heat from the higher temperature side is transferred to the other side via the heat transfer member or spacer, thereby reducing the temperature difference between both sides of the substrate or between the two optical disk plates. This suppresses deformation of the optical disc.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1(a) and 1(b) show an optical disc according to an embodiment of the present invention. In this figure, the same parts and corresponding parts as in FIG. 4 are given the same reference numerals.

In the figure, the entire recording surface 1a of the substrate 1,
At the outer circumferential side surface 1c, the hole 3 formed on the inner circumferential side, and the outer circumferential side and inner circumferential side ends of the surface 1b of the substrate 1,
A thermally conductive member 20 made of a material having higher thermal conductivity than the substrate 1 is provided.

With the above configuration, when this optical disc is mounted in an optical disc drive for access, the surface 1b is heated by the heat source of the optical disc drive, and the heat conductive member 20 is also heated.

The amount of heat conducted to this heat conducting member 20 is:
A portion of the heat is transmitted to the recording surface 1a via the heat conductive member 20, and thereby the amount of heat is transmitted to the recording surface 1a, thereby heating the recording surface 1a.

[0020] In this way, the thermally conductive member 20
Since the recording surface 1a and the surface 1b are thermally coupled, when the surface 1b is heated by the heat source of the optical disk drive, the temperature of the recording surface 1a increases accordingly, and the temperature difference between both sides of the substrate 1 increases. reduced.

As a result, the deformation of the substrate 1 is suppressed, so that the servo control system for accurately positioning the laser beam of the optical pickup device for recording/reproducing data on the optical disk onto the recording surface of the recording layer 2 is suppressed. It is possible to prevent inconveniences such as fluctuations in the amount of offset in the disc or crosstalk caused by simultaneous irradiation of laser beams onto adjacent recording tracks.

Furthermore, if the heat conductive member 20 is made of a non-magnetic material, such as aluminum, when recording/erasing data on the magneto-optical disk, the external magnetic field acting on the magneto-optical disk is transferred directly to the magneto-optical disk. Since it can act on a disk, in that case, the present embodiment can also be applied to a magneto-optical disk.

FIG. 2 shows an optical disc according to another embodiment of the invention. In addition, in the same figure, FIG. 1(a)
, (b) and corresponding parts are given the same reference numerals.

In this case, a heat conductive member 21 is provided in the hole 3 and in a portion connecting the recording surface 1a and the surface 1b.

In this case, when the surface 1b is heated by the heat source of the optical disk drive, the amount of heat is transferred to the heat conductive member 21.
The temperature of the recording surface 1a also increases as the temperature of the surface 1b increases.

Therefore, since the temperature difference between both surfaces of the substrate 1 is reduced, deformation of the substrate 1 is suppressed, and the laser beam of the optical pickup device is accurately directed onto the recording surface of the recording layer 2, as in the above embodiment. It is possible to prevent inconveniences such as fluctuations in the amount of offset in the servo control system for positioning, or occurrence of crosstalk due to simultaneous irradiation of laser beams to adjacent recording tracks.

FIG. 3 shows an optical disc according to still another embodiment of the present invention. In addition, in the figure, the same parts and corresponding parts as in FIGS. 1(a) and 1(b) are given the same reference numerals.

In the figure, this optical disc is constructed by bonding together two substrates 1 and 1' having the same structure as substrate 1, and substrates 1 and 1' have recording layers 2 and 1', respectively. The recording layers 2' are arranged to face each other, and spacers 25 are provided on the inner and outer circumferential sides of the substrates 1 and 1' to maintain the distance between the substrates 1 and 1'.
26 is fixed with adhesive.

The spacers 25 and 26 are attached to the substrates 1 and 1'.
It is made of a material with higher thermal conductivity and elasticity.

[0030] Therefore, when this optical disc is installed in an optical disc drive device, among the substrate 1 and the substrate 1',
The amount of heat of the higher temperature one is transferred to the other via the spacers 25 and 26, thereby reducing the temperature difference between the substrates 1 and 1'.

As a result, deformation of the optical disc is suppressed,
Similar to the embodiments described above, the amount of offset in the servo control system for accurately positioning the laser beam of the optical pickup device on the recording surface of the recording layer 2 may vary, or the laser beam may simultaneously strike adjacent recording tracks. It is possible to prevent inconveniences such as crosstalk caused by irradiation.

Furthermore, if the spacers 25 and 26 are made of a non-magnetic material that has higher thermal conductivity than the substrates 1 and 1' and is elastic, data can be recorded on the magneto-optical disk. /Since the external magnetic field that acts on the magneto-optical disk when erasing can be applied directly to the magneto-optical disk,
In that case, this embodiment can also be applied to a magneto-optical disk.

[0033]

[Effects of the Invention] As explained above, according to the present invention,
The amount of heat from the higher temperature side moves to the other side via the heat transfer member or spacer, thereby reducing the temperature difference between both sides of the substrate or the temperature difference between two optical disk plates, causing deformation of the optical disk. This has the effect of suppressing the

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an optical disc according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing an optical disc according to another embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing an optical disc according to still another embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a conventional example of an optical disc.

FIG. 5 is a schematic configuration diagram showing an example of an optical disc drive device.

FIG. 6 is a partial cross-sectional view showing the disadvantages of the prior art.

FIG. 7 is a partial cross-sectional view showing another disadvantage of the prior art.

[Explanation of symbols]

1, 1' board 1a Recording surface 1b side 1d side 2 Recording layer 3 holes 4 Hub member 20, 21 Heat conductive member 25, 26 Spacer

Claims (3)

[Claims] Claim 1: An optical disc comprising an optical recording medium laminated on one side of a disc-shaped substrate made of a transparent material,
A heat transfer member made of a material having higher thermal conductivity than the substrate is provided, which connects the other surface of the substrate and the surface on which the optical recording medium is laminated at a portion that avoids the area where the optical recording medium is disposed. An optical disc characterized by: 2. The optical disk according to claim 1, wherein the heat transfer member is made of a non-magnetic material. 3. Two optical disk plates each having an optical recording medium laminated on one side of a disk-shaped substrate made of a transparent material are arranged in such a manner that the optical recording medium laminated surfaces face each other, and In an optical disk that is fixed with a predetermined distance maintained through two sets of spaces provided on the inner circumferential side and on the outer circumferential side, the two sets of spacers are made of a material with higher thermal conductivity than the substrate. An optical disc featuring