CN1007187B - CD - Google Patents

Abstract

The invention relates to an optical disc structure capable of suppressing distortion of an optical disc substrate (1) due to temperature changes. A disk (3) with a specific diameter is mounted almost in the center of the disk base. An information recording layer (2) is provided at a specific portion of the disc substrate, and the bonding portion where the disc is bonded to the disc substrate is made of a material having a coefficient of thermal expansion almost equal to that of the disc substrate.

This disc can be used in devices such as memory of electronic computers.

Description

The present invention relates to an optical disc.

Fig. 1 is a perspective view of a prior art optical disc. In the drawings, numeral (1) denotes a disc-shaped base made of polycarbonate or the like having a hole (1a) (hole diameter, for example, 15 mm) in the center. (2) represents an information recording layer, which is concentrically formed on a specific portion of the disc substrate (1) for recording and reproducing information by means of input and output devices not shown in the figure. (3) Indicates a disc made of magnetic material, the outer diameter of which is smaller than the inner diameter of the information recording layer. The optical disc (4) is made by bonding one disc (3) to the upper surface of the disc base (1) with an adhesive, and then bonding the other disc (3) to the lower surface of the disc base (1), The base is thus interposed between a pair of disks (3).

Figure 2 is a sectional view of an optical disc (4) mounted on an optical disc drive, wherein the disc (3) is held by magnets (5a) mounted on the disc turntable (5) to hold the disc in place. The disc (4) can be rotated by turning the disc turntable (5). In this case, by irradiating the information recording layer (2) with a laser beam, information can be recorded on or read from the information recording layer (2).

Japanese Patent Application Sho 60-43242 (published March 7, 1985) also discloses an optical disc comprising a substrate having an information recording medium and a centering disc formed of a magnetic material.

In the above-mentioned prior art optical disk, there is a difference between the thermal expansion coefficient (7×10 ^-5 mm/°C) of the disc substrate (1) and the thermal expansion coefficient (1×10 ^-5 mm/°C) of the magnetic disk (3), resulting in There is a problem that the disc substrate (1) having a large thermal expansion coefficient is distorted by a change in the internal temperature of the optical drive. This distortion causes a greater change in the birefringence of the laser beam irradiated from the disc substrate when reading out information, thereby increasing noise during reproduction of information.

The present invention is proposed to solve the above-mentioned problems. SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk capable of suppressing distortion caused by temperature changes.

The optical disk of the present invention includes a disk substrate, a disk of a specified diameter, and a portion where the disk is bonded to the disk substrate. The disc base has an information recording layer at a specific radial position, and a disc with a specific diameter is installed almost in the center of the disc base, and the bonding part between the disc and the disc base is made of a material whose thermal expansion coefficient is almost equal to that of the disc base. production.

Since the disc-to-disk base bonded portion is made of a material having a thermal expansion coefficient almost equal to that of the disc base according to the present invention, the disc base can be prevented from being affected by thermal expansion of any portion other than the bonded portion, thereby suppressing the occurrence of thermal expansion on the disc. Distortion due to temperature changes.

Fig. 1 is a perspective view of a prior art optical disc.

Fig. 2 is a sectional view of a prior art optical disc.

Fig. 3 is a configuration diagram of an optical disc according to an embodiment of the present invention, wherein (a) is a perspective view and (b) is a sectional view.

Fig. 4 is a configuration diagram of an optical disc according to another embodiment of the present invention, wherein (a) is a perspective view and (b) is a cross-sectional view.

Fig. 5 is a perspective view of an optical disc according to yet another embodiment of the present invention.

Fig. 6 is a perspective view of an optical disk according to yet another embodiment of the present invention.

Fig. 3 is a configuration diagram of an optical disc according to an embodiment of the present invention, wherein (a) is a perspective view and (b) is a cross-sectional view. In the figure, numerals (1), (2) and (3) denote the same components as those of the above-mentioned prior art. Number (7) denotes a disk interposed between the disk base (1) and the disk (3). The disk (7) is made of a material (such as polycarbonate) with a thermal expansion coefficient almost equal to that of the disk base, and the inner and outer diameters of the disk (7) are almost the same as those of the disk (3). In addition, the disk base (1), disk (7) and disk (3) are sequentially bonded with a specific adhesive.

In the optical disk of this embodiment, a disk (7) having a thermal expansion coefficient almost equal to that of the disk substrate (1) is interposed between the substrate (1) and the disk (3), and their respective thermal expansion coefficients are different from each other. Therefore, when any part of the optical disc expands with heat and contracts with cold due to temperature changes, distortion does occur on the disc (3), However, the disc (7) reduces the distortion generated on the disc base (1).

Fig. 4 is a schematic view of an optical disc according to another embodiment of the present invention, wherein (a) is a perspective view, and (b) is a cross-sectional view.

In the drawings, numerals (1), (2) and (3) denote almost the same components as in the above-mentioned prior art. Reference numeral (8) designates holes formed in the disk (3) on the periphery of concentric circles of a certain diameter, each hole being tapered at its end. (9) represents a fixing member, and the disk base (1) is connected to the disk (3) by means of the fixing member (9). The fixing member ( 9 ) is made of almost the same material as the disc base ( 1 ), such as polycarbonate, with a diameter such that it can be inserted into the hole ( 8 ). The head of the fixing member (9) is designed such that it fits into the countersink of the hole (8). The fixing member (9) is designed to be longer than the width of the disc (3) to a certain extent, forming a welded part of a specific structure on the surface facing the disc base (1), and connecting the disc base (1) and the disc (3) , welded with an ultrasonic welding device.

According to the optical disc composed as above, when the disc base (1) and the disc (3) expand due to heat, since the thermal expansion coefficient of the fixed member connected is almost equal to that of the disc base (1), the disc base (1) is reduced. ) and the difference in thermal expansion coefficient between the disc (3).

In addition, the head of the fixing member (9) is designed according to the shape of the hole in the above-mentioned embodiment, but the two ends of the rod-shaped fixing member with a diameter almost the same as the hole are welded together with a thermal gap filling device, so that it can be compared with the above-mentioned The same effect of the embodiment can also achieve satisfactory results.

Fig. 5 is a perspective view of an optical disk according to another embodiment of the present invention, in which numerals (1) and (2) denote the same parts of the above-mentioned prior art. The number (10) indicates a disk made of soft magnetic material with a specific outer diameter (the specific outer diameter is smaller than the inner diameter of the information recording layer (2)) and a specific inner diameter. The disc (10) is molded with, for example, a material whose main composition is Fe-Al-Si (which has a coefficient of thermal expansion of about 6.7 x 10 ^-5 mm/°C) and which has a certain magnetization. In such optical disks, the difference in their respective coefficients of thermal expansion is small, so that the distortion generated in the disk substrate upon thermal expansion is reduced.

In addition, the soft magnetic materials for making optical discs are not limited to iron-aluminum-silicon, like manganese-zinc-silicon, Nickel-zinc-silicon or the like can also satisfactorily obtain the same functions as the above-described embodiments.

Fig. 6 is a perspective view of an optical disk according to yet another embodiment of the present invention. In the figure, numbers (1) and (2) are the same as the above-mentioned prior art. Reference numeral (11) designates a disc having specified inner and outer diameters and molded of substantially the same material as the disc base (1) mixed with magnetic material. The disk (11) is bonded to the disk base with a special adhesive. When the disk base (1) is made of polycarbonate and the like, the disk (11) is made of polycarbonate filled with a certain amount of magnetic powder, and the magnetic powder is mixed with polycarbonate to make it distributed according to regulations. , and mold the mixture with a molding device.

In the optical disc configured in this way, the thermal expansion coefficients of the base (1) and the disc (11) are not much different, thus greatly reducing the distortion produced by the disc base (1).

In this regard, the amount of magnetic powder added to the disk (11) should be adjusted at least to the amount of magnetic material that the disk can be held by the magnets of the disk drive and fixed thereto.

The invention can be applied to optical discs used for electronic computer memory to suppress distortion of the optical discs.

Claims (2)

1. An optical disc comprising a disc base having an information recording layer at a specific portion, and a disc having a specific diameter mounted almost at the center of the disc base, characterized in that the bonding portion of the disc and the disc base is formed by a made of a material with a thermal expansion coefficient almost equal to that of the disc substrate. 2. The optical disc according to claim 1, wherein said disc has a plurality of holes in which a fixing member having an adhesive portion bonded to the disc base is inserted.

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