JPH01134772A - Optical information recording disk for magnetic clamping - Google Patents

Abstract

PURPOSE:To improve a strength and an anti-abrasion character by forming a holder of a resin material in which a filler is mixed by a proper quantity. CONSTITUTION:A holder 3 is formed with the resin material in which a granular or fibrous filler is mixed. For the resin material in which the proper filler is mixed by the proper quantity in such a way, while a thermal expansion coefficient is held to be approximately equal, the strength and anti-abrasion character can be improved. Consequently, such a holder 3 formed of the filler- mixed-in resin is hard to be scarred and deformed even at the time of being repeatedly mounted on a turntable, and the deterioration of an appearance and a mounting easiness can be canceled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording device for a magnetic clamp equipped with a magnetic attracting member that is attracted by a disk attracting magnet provided on a turntable of a recording/reproducing device. Regarding discs.

[Conventional technology]

Conventionally, this type of optical information recording disk has a substrate made of a ceramic material such as glass or a resin material such as polycarbonate or polymethyl methacrylate, and a metal material such as a magnetic stainless steel plate placed at the center of the outer surface of the substrate. A device in which formed magnetic adsorption members are directly bonded is known.

In this optical information recording disk for magnetic clamping, when environmental conditions, especially temperature change, thermal stress due to the difference in coefficient of thermal expansion between the substrate material and the magnetic adsorption material acts on the substrate.
Regarding resin substrates, there is a problem in that retardation (birefringence) occurs in recording/reproducing light passing through the substrate, which inhibits normal recording/reproduction. Further, glass substrates have a problem in that they have high internal stress and are easily broken.

In order to solve the problems of the prior art, the applicant of the present application,
First, a resin holder having a coefficient of thermal expansion approximately equal to that of the substrate material was integrally molded on the outer periphery of a magnetic adsorption member similar to the above, and this holder was fixed to the center of the outer surface of the substrate, and the above-mentioned one. We proposed a frame-shaped holder made of a similar resin material fixed to the center of the outer surface of the board, and a magnetic adsorption member loosely fitted into the space formed by these holders and the board. 61-282845).

Among the optical information recording disks for magnetic clamps previously proposed by the applicant, the former has a magnetic adsorption member attached to the substrate via a resin holder, so that it can be easily attached to the substrate when environmental conditions such as temperature change. Strain caused by the difference in coefficient of thermal expansion between the material and the magnetic adsorption material is absorbed by the highly elastic resin holder, and the stress acting on the substrate can be alleviated. In addition, since the latter loosely fits the magnetic adsorption member into the holder, the strain caused by the difference in thermal expansion coefficient between the substrate material and the magnetic adsorption material is completely absorbed into the gap formed between the holder and the magnetic adsorption member. The thermal stress is absorbed by the substrate, and no thermal stress is applied to the substrate. Therefore, for resin substrates, the recording/reproducing characteristics can be improved by reducing turbulence, and for glass substrates, cracking can be prevented.

[Problem that the invention seeks to solve]

However, subsequent experiments revealed that the holder of the optical information recording disk for magnetic clamp that was previously proposed by the applicant was made of a flexible resin material, so it was difficult to turn the disk when it was installed in a recording/playback device. It has been found that the holder tends to be easily damaged due to collision with the corners of the table, causes minute abrasions, resulting in poor appearance, and deforms the holder, making it difficult to attach it to the turntable.

The present invention has been made to solve the problems of the prior art described above, without diminishing the advantage of alleviating the stress acting on the substrate.

The object of the present invention is to provide an optical information recording disk with excellent strength and wear resistance.

[Means for solving problems]

In order to achieve the above object, the present invention is characterized in that the holder is made of a resin material mixed with powdery or fibrous filler to improve strength and wear resistance.

[Effect]

A resin material mixed with an appropriate amount of an appropriate filler can improve strength and wear resistance while maintaining almost the same coefficient of thermal expansion. Therefore, a holder made of such filler-containing resin is unlikely to be damaged or deformed even if it is repeatedly mounted on a turntable, and deterioration in aesthetic appearance and ease of mounting can be avoided. Furthermore, thermal stress acting between the substrate and the holder does not pose a practical problem.

〔Example〕

FIG. 1 is a sectional view of an optical information recording disk showing an embodiment of the present invention, in which l and la are substrates, 2 is a magnetic adsorption member,
3 indicates a holder that holds the magnetic attraction member 2. As shown in FIG.

The substrates 1 and 1a are completely similar to conventional ones, and are made of a transparent material such as glass, polycarbonate, polymethyl methacrylate, or epoxy, and are arranged in concentric circles around the central axis of the central hole 4. A signal pattern 5 such as a guide track or prepit is formed in a shape or a spiral shape, and a desired recording film 6 is formed on the surface on which the signal pattern 5 is formed.

The magnetic attraction member 2 is formed into a disk shape with a through hole 7 in the center. The magnetic adsorption member 2 can be formed using any magnetic material such as soft iron, ferritic stainless steel, or martensitic stainless steel, but since it is resistant to rust and can be obtained relatively inexpensively, , JIS standard 5US430 stainless steel is particularly suitable.

Further, this ferromagnetic attraction member 2 can be of any thickness, but if it is too thin, the attraction force against the magnet will be weak, making it difficult to accurately transmit the driving force of the spindle to the optical information recording disk. This poses a problem in that it cannot be used or is easily deformed or worn out by external force, resulting in poor durability. On the other hand, if it is too thick, problems such as the optical information recording disk becomes heavy and the drive mechanism becomes large, or the processing of the magnetic adsorption member 2 becomes difficult and the cost of the optical information recording disk increases.

For these reasons, the thickness of the magnetic adsorption member 2 is 0,
2-0, about 8 mm, more preferably 0.3-0
．． About 5mm is good.

The holder 3 is molded from a resin material mixed with a powdery or fibrous filler.

Alumina (Alz Oa) is used as a powdery filler.
or silica (SiC2), and as the fibrous filler, carbon fiber, glass fiber, etc. are suitable.

Between the powder filler and the fibrous filler, it is more preferable to use the fibrous filler from the viewpoints of strength, abrasion resistance, and ease of molding. Note that it is of course possible to use a mixture of the various fillers described above.

As the resin material forming the holder 3, any resin material can be used. However, in order to make the coefficient of thermal expansion of the holder 3 as close as possible to that of the substrate 1, it is preferable to use the same resin material as the resin material constituting the substrate. Furthermore, in order to improve the ease of mounting on the turntable and reduce scratches, it is also effective to use resin materials with excellent lubricity, such as polyamide, polyimide, polyimideamide, polyacetal, and polypropylene.

The mixing ratio of the filler to the resin material is preferably 10% or less, more preferably 2% to 3%. In order to improve strength and wear resistance, the higher the mixing ratio of filler to the resin material, the more effective it is, but if it exceeds 10%, the moldability will be significantly impaired, making it impossible to secure the minimum yield required for mass production. It is.

The shape of the holder 3 can be appropriately designed as necessary. For example, as shown in FIGS. 1 and 2, the magnetic attraction member 2 can be integrally insert-molded into a cylindrical shape, or as shown in FIG. The member 2 can also be formed into a substantially U-shape having a size that allows it to be loosely fitted.

The outer diameter of the holder 3 can be designed as needed, but if the diameter is too small, the stability when attached to the turntable of a recording/reproducing device will be impaired, and on the other hand, if the diameter is too large, the recording area will be affected. 24mm~
It is preferable to set it to about 32 mm. Further, the thickness h of the holder 3 can be appropriately designed as needed, but if it is too thin, it will be difficult to handle when molding or fixing to the substrates 1, 1a, and on the other hand, if it is made too thin, it will be difficult to handle when it is fixed to the substrates 1, 1a. This may cause problems such as difficulty in designing the disk cartridge in which the optical information recording disk is stored, or the possibility of foreign objects colliding with each other during handling.
In particular, it is preferable to set it to about 2 mm.

Further, the holder 3 has a structure as shown in FIG.

In order to facilitate mounting on a turntable, it is preferable to chamfer 8 on the outer periphery of the outer surface. Of course.

The shape of this chamfer 8 may be an inclined surface or a curved surface, and its size is preferably about 0.3 to 1.0 mm.

Further, as shown in FIG. 5, in order to prevent excess adhesive from leaking to the outside, it is preferable to form an adhesive reservoir 9 on the inner and outer peripheral portions. The adhesive reservoir 9 is formed by cutting the edge portion into an inclined or curved shape. The size can be arbitrarily designed, but if it is too large, the bonding area will become small and the bonding strength will be impaired, so it is preferably about 0.3 to 1.0 mm. Note that the holder 4 and the transparent substrate 2゜2
Any known adhesive can be used as the adhesive for bonding a to a, but it is preferable to use a photocurable resin because of its good workability.

In the optical information recording disk of the above embodiment, the holder 3 is made of a resin material mixed with an appropriate amount of filler, so it has excellent strength and wear resistance, and will not be scratched or deformed even if it is repeatedly mounted on a turntable. There's not much to do. Also,
Since the coefficient of thermal expansion of the holder is almost equal to that of the substrate,
Thermal stress acting between the substrate and the holder is minute, and there is no problem with deterioration of recording/reproducing characteristics or cracking of the substrate.

The gist of the present invention is that the holder is formed of a resin material mixed with an appropriate amount of filler, and the shapes and materials of the substrate, magnetic adsorption member, and holder are limited to those listed in the above embodiments. It is not something that will be done. Furthermore, the disk structure is not limited to the air sand inch structure. These can be appropriately designed as necessary.

〔Effect of the invention〕

As explained above, the optical information recording disk of the present invention has
Since the holder is made of a resin material mixed with an appropriate amount of filler, it has excellent strength and wear resistance, and is unlikely to be damaged or deformed even if it is repeatedly mounted on a turntable. Furthermore, since the coefficient of thermal expansion of the holder is approximately equal to that of the substrate, there are no problems with deterioration of recording/reproducing characteristics or cracking of the substrate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the overall structure of an optical information recording disk according to a first embodiment of the present invention, and FIGS. 2 to 5 are sectional views showing main parts of modified examples of the holder. 1, la: substrate, 2: magnetic adsorption member, 3: holder, 4:
Central hole, 5: Signal pattern, 6: Recording film, 7: Through hole, 8
: Chamfer, 9: Adhesive reservoir. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A holder made of a resin material having approximately the same coefficient of thermal expansion as the substrate is adhered to the center of the substrate, and a ring-shaped magnetic adsorption member is placed inside the space formed by the substrate and the holder. 1. An optical information recording disk for magnetic clamping, characterized in that the holder is made of a resin material mixed with powdery or fibrous filler. (2) In the optical information recording disk for magnetic clamp according to claim (1), the filler may include alumina (Al_2O_3), silica (SiO_
2) An optical information recording disk for a magnetic clamp, characterized in that it uses at least one substance selected from carbon and glass. (3) In the optical information recording disk for magnetic clamping according to claim (1), the mixing ratio of the filler mixed into the resin material is 2% to 3%. Optical information recording disk for magnetic clamp.