JPH01292643A - Optical disc manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing an optical disc in which information is recorded and reproduced using light such as a laser beam.

[Conventional technology]

Optical discs perform tracking by detecting concentric or spiral guide grooves or pit rows provided on the disc.In order to reduce tracking defects, the center of the guide groove or pit row, It is necessary to reduce the eccentricity between the optical disk and the center hole, which is the center of rotation of the optical disk. Therefore, when manufacturing the stamper, it is necessary to have good dimensional accuracy to prevent eccentricity, and to mold the optical disk substrate using a mold in which the stamper is set without eccentricity. Even if the dimensional accuracy of the stamper and mold is improved,
For example, there is one described in Japanese Patent Application Laid-Open No. 61-63941. In the figure, (LA) and (IB) are disk-shaped optical disk substrates, (2A) and (2B) are optical disk substrates (IA) on which guide grooves and pit rows (both not shown) are formed, and (tB). ) recording section, (3A),
(3B) are the optical disk substrate (IA) and (I
B) has a hole in the center of the substrate, (4) is the optical disc substrate (IA), and (tB) is the substrate adhesive that is interposed between them to bond them together; (5A) and (5B) are the outer shapes of the recording section. (2
The inner diameter of A) and (2B) is smaller than the diameter of the rigid circle, which is the dimension required by the product specifications. (
7) is a rigid disc adhesive that is interposed between the optical disc substrate (IA) and the rigid disc (5A) and between (IB) and (5B) to bond them together. ),
They are attached so that the center of (6B) coincides with the center of the guide groove or pit row (both not shown) formed in the recording parts (2A) and (2B).

When recording and reproducing information using an optical disk, the optical disk is fixed to a recording or reproducing device (not shown) and driven to rotate with reference to the rigid center holes (6A) and (6B). As mentioned above, tracking is performed by detecting the guide groove or pit row (not shown), but since the center of the guide groove or pit row (not shown) coincides with the center of rotation of the optical disc. , there are few tracking defects.

[Problem to be solved by the invention]

Conventional optical discs are structured as described above, so
The center of the optical disk becomes thicker than standard by the thickness of the attached rigid disks, making it difficult to mechanically fit with recording or playback equipment.Also, if the adhesive for rigid disks is not evenly applied, the rigid disk The horizontality of the disk attachment becomes poor, causing rotational wobbling of the optical disk, or the adhesion of the rigid disk causes distortion, which spreads to the recording section and deteriorates the optical characteristics of the recording section. There have been problems with recording and reproducing characteristics using laser light.

This invention was made to solve the above-mentioned problems, and it is an optical disc that does not mechanically fit with a recording or reproducing device or suffers from rotational vibration, and has good recording and reproducing characteristics. The purpose is to obtain a manufacturing method for.

[Means to solve the problem]

The method for manufacturing an optical disc according to the present invention includes a first step of molding a disc-shaped optical disc substrate having a central hole having a diameter smaller than a predetermined size and a thin part thinner than the recording part in the vicinity of the central hole. and a third step of heating the thin wall portion to a temperature higher than the thermal deformation temperature of the thermoplastic plastic material to deform the center hole so that the diameter has the predetermined size and the center coincides with the center of the guide groove or pit row. It consists of two steps.

[Effect]

The center hole of the disk-shaped optical disk substrate molded in the first step is smaller than the predetermined dimension required by the product specifications, so if the difference from this predetermined dimension is within the center hole, the center hole can be made up to the predetermined dimension. When increasing the size, eccentricity can be corrected at the same time. In the second step, the temperature near the center hole is raised above the thermal deformation temperature of the thermoplastic material, so the center hole can be easily enlarged. The surplus material produced by enlarging the center hole is absorbed by filling the thin line near the center hole.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view showing an optical disk substrate formed in the first step of the method for manufacturing an optical disk according to an embodiment of the present invention. In the figure, (1) is a disc-shaped optical disk substrate, (2)
) is a recording section in which guide grooves and pit rows (both not shown) are formed, and (3) is a central hole, the diameter of which is smaller than a predetermined size required as a product specification. (8) is a thin part provided near the precaution hole (3), and is a recording part (2).
) is thinner than the FIG. 2 is a cross-sectional view showing the second step following the first step, where (9) has a diameter of
It is a round rod with the same dimensions as the predetermined dimensions required by the product specifications for the center hole (3) of the optical disc, and has a corner section cut off at the tip, making it movable in the axial direction. αq is a round bar (9
The collar αη, which is fitted into the ring and fixed at a position set back from the tip of the round bar (9) by a dimension equal to or more than the thickness of the optical disc substrate (1), has an inner diameter slightly larger than the outer diameter of the round bar (9). The large cylindrical receiver is a ring, and in the figure, the soil surface is the recording part (
2) It is arranged so that it is on the extension surface of the lower surface.

(12A) and (12B) are cylindrical metal outer rings placed outside the ring αη. It is in contact with the upper or lower surface of (8).The central axes of (9) to 12A) and (12B) are arranged to coincide with each other.

Next, the operation will be explained. First, in the first step, a disc-shaped optical disk substrate (1 inch is made of thermoplastic plastic as shown in Figure 1) is injection molded or compressed using a stamper, mold, etc., as in the conventional method. Made by molding.

Next, in the second step shown in FIG. 2, using a positioning jig (not shown), guide grooves or pit rows (
The optical disc substrate (1) is held so that the central axis of the round bar (not shown) coincides with the central axis of the round bar (9). Round bar (9)
initially recedes upward in the figure, and is heated by a heating device (not shown) to a temperature higher than the thermal deformation temperature of the thermoplastic that is the material of the optical disc substrate (1). Next, the round bar (9) is advanced downward in the figure. Since the center hole (3) is made smaller than the diameter of the round bar (9) in the first step, the tip of the round bar (9) hits the thin wall part (8), and the spot where it hits is the part of the round bar. It is heated to the temperature of (9) and softened. As the round bar (9) is advanced downward in the figure, the eccentricity of the center hole (3) is corrected, the center hole (3) is enlarged and deformed to the above prescribed dimensions, and the thin part (8) is penetrated. do.

At this time, the excess material corresponding to the enlargement of the center hole (3) builds up around the center hole (3), but the rise (2) Haba QO and Uke are suppressed. , it does not protrude from the extended surface of the upper and lower surfaces of the recording section (2). Also, the heat transmitted from the round bar (9) to the thin wall part (8) is absorbed by the outer rings (12A) and (12B) and dissipated, and since the heat transmitted to the recording part (2) is not small, its characteristics deteriorate. Never. After the above operation, the round bar (9) retreats upward in the figure.

The diameter of the round bar (9) is the same as the above-mentioned predetermined dimension required for the center hole (3), and the central axis of the guide groove or pit row (not shown) of the optical disc substrate (January) is the round bar. (9
), the center hole (3) after deformation has a diameter of the above prescribed size and whose center coincides with the center of the guide groove or pit row (not shown). becomes.

In addition, in the above embodiment, the receiver is the ring (b) and the recording part (2).
Although it was placed so that it was within the extended plane of the lower surface of the
It may be arranged so as to be in contact with the lower surface of the. Further, although a single optical disk substrate is shown, the present invention can also be applied to a structure in which two optical disk substrates are bonded together as shown in FIG.

[Effects of the Invention] As described above, according to the present invention, since a rigid disc is not used, the central part does not become thicker than the standard and becomes difficult to mechanically fit with a recording or reproducing device, and adhesive for rigid discs is not used. There is no rotational wobbling due to uneven application of the agent, and there is no distortion due to adhesion of the rigid disk, so it is possible to obtain an optical disk with good recording and reproducing characteristics.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an optical disk substrate formed in the first step of an optical disk manufacturing method according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the second step following FIG. 1, and FIG. FIG. 3 is a sectional view showing a conventional optical disc. In the figure, (1) is the optical disc substrate, (February recording part), (3) is the center hole, (8) is the thin part, and (9) is the round bar. In each figure, the same reference numerals are the same. , or a corresponding portion. Agent: Patent Attorney Masuo Oiwa

Claims (1)

[Claims] In a method for manufacturing an optical disc made of thermoplastic plastic having a recording section provided with a guide groove or a pit row,
a first step of molding a disc-shaped optical disc substrate having a center hole having a diameter smaller than a predetermined size and a thin part provided near the center hole and having a thickness thinner than the recording part;
and a second heating the thin part to a temperature higher than the thermal deformation temperature of the thermoplastic plastic to transform the center hole so that its diameter is the predetermined size and its center is aligned with the center of the guide groove or pit row. A method for manufacturing an optical disc, which comprises the steps of: