JPS59203253A - Optical disc and its production - Google Patents

Abstract

PURPOSE:To prevent the loss of information due to defects by laminating a grooved resin substrate, an optical recording medium layer covering the groove surface, a photo-setting adhesive which covers the optical recording medium layer, and a light-transmissive resin layer covering this adhesive in order from the side opposite to the irradiation direction of an optical signal. CONSTITUTION:A recording medium 7 such as a Te oxide or the like is vapor- deposited onto the gooved surface of a substrate 8 of a grooved resin disc, and a photo-setting adhesive 6 is applied uniformly onto this medium 7, and a transparent protecting resin plate 5 is put on this adhesive 6, and ultraviolet rays are irradiated, thus forming an optical disc. When a recording and reproducing laser light emitted from a laser 9 is irradiated through a condenser lens 14, the laser light is condensed through the resin plate 5 and the adhesive layer 6 successively to become spot light having about 1mum and reaches the surface of the recording medium 7. In this case, since the diameter of the projected laser light is large, recording and reproducing of information are not damaged by foreign matters, which are stuck onto the resin plate 5 and have above 100mum size, and foreign matters having <=10mum size in the resin plate 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc in which video, audio, and data signals are all-optically modulated and recorded and reproduced using a laser beam, and a method for manufacturing the same.

Conventional Structure and Problems The structure and recording/reproduction of a conventional optical disk will be explained with reference to FIG. The structure of the Sunzu optical disk is that a disk base with thick grooves is molded by compression molding or injection molding, and is adhered to the surface of the disk base 1 using a laser method.The recording medium 2 is generally made of bismuth or molybdenum. , tellurium, cobalt, nickel, arsenic, zinc, tin, etc. Further, an adhesive layer 3 is provided on the recording medium 2, and a transparent resin plate 4 is bonded to the recording medium 2 to protect the surface of the recording medium, thereby constructing an optical disk.

Recording and playback of this original disc is performed in 1 of disc base 1 (↓
A laser beam 12 from 11 is converged by a lens 14. Note that the laser beam 12 is generated from the laser 9 and enters the lens 14 through the entire optical system 10. Part of the light that reaches the recording medium 2 is reflected, and the same optical path is passed through the photodetector 1 with the same diameter.
1, is converted into an electrical signal, and is output as an electrical signal 13. In this case, since the cross-sectional area of the laser beam light has not yet been sufficiently converged with respect to the foreign matter adhering to the surface of the disk base 10, the percentage of the laser light being blocked by the foreign matter is small. However, since the laser beam that reaches the vicinity of the recording medium 2 is narrowed down to a spot of around 1 μm, the foreign matter present near the recording medium 2 has a diameter of around 1 μm (772 μm). A loss occurs in the playback information.

Therefore, in the optical disc having this structure, there are no small foreign substances in the resin material used for the disc base 1, and the disc base 1
Optical homogeneity is required over the entire surface, and it has been extremely difficult to select materials and molding methods suitable for this purpose. In reality, it is difficult to realize an optical disc for document files and data files that requires a small error rate with this configuration.

Purpose of the Invention The present invention solves all of the above-mentioned problems with the conventional original disc, such as the presence of a large number of foreign substances in the grooved disc base, or the fact that the molding does not proceed smoothly and optical defects occur. The object of the present invention is to provide an optical disc that is homogeneous but does not suffer from loss of information.

Structure of the Invention The optical disc of the present invention includes, from the side opposite to the irradiation direction of an optical signal, a resin substrate with grooves, an optical recording medium layer that covers at least the surface of the groove, and a photocurable layer that covers the optical recording medium layer. The adhesive and the light-transmitting resin layer covering the photocurable adhesive are arranged in sequence.

The method for manufacturing an optical disk of the present invention includes a step of molding a grooved resin optical disk substrate by injection molding or compression molding, a step of bringing a recording medium that can be recorded and played back with light into close contact with this substrate, and a step of making the recording and playback process possible. This method consists of a step of applying a transparent photocurable adhesive onto the medium, and a step of overlaying a transparent protective resin plate over the adhesive and irradiating it with ultraviolet rays to bond the protective resin sheet metal.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 2 is a sectional view showing an optical disc of the present invention. 8 is a grooved resin disk substrate obtained by compression or injection molding, and a tellurium oxide recording medium 7 is adhered to the grooved surface by vapor deposition or the like. Thereafter, a photocurable adhesive 6 filtered and refined through a transparent filter with a roughness of 0.2 μm is applied to the surface of the recording medium to a uniform thickness of 50 to 20,011 m, and a transparent protective resin plate 5 is overlaid on top of the photocurable adhesive 6, which is exposed to ultraviolet light. Irradiated and glued? to create the original disc.

FIG. 3 is a conceptual diagram showing a method for regenerating optical tissue according to the embodiment of the present invention. The laser f emitted from the laser 9 is the optical system iof! : The focused laser beam passes through the condensing lens 14 and is focused as shown by the arrow 12 while passing from the protective resin plate 5 to the original hardened adhesive layer 6 in a diameter direction to the recording medium 7.
It reaches the surface of the photodetector 1 and is partially reflected, and the same optical path is passed through the photodetector 1.
1 and is converted into an electrical signal and output as an electrical signal 13. In fact, all optical discs made using this method were recorded and reproduced using the method described above. When acrylic resin was used as a protective plate, the error rate was (t-48×10, -!) when polycarbonate resin was used as a protective plate. Sometimes it was 3x10.

In this way, the error rate has decreased due to the following reasons: laser beam VJ for recording and reproduction, transparent protective resin plate 5
As the photocurable resin adhesive layer 6 is sequentially narrowed down by diameter, it finally becomes a spot light of around 1 μm on the recording medium 70.
It reaches the surface.

In this case, it depends on the numerical aperture of the lens, but for a lens with a numerical aperture of about 05, the amount of 100 μ?
Since the diameter of the laser beam is large, the laser beam is blocked by a foreign particle with a diameter of around 1Q11227 or a foreign particle with a diameter of up to 1Q11227 present in the resin, so that there is almost no loss in the recording and reproduction of information.

However, in the photocurable adhesive layer 6 where the laser beam is focused, even a foreign particle with a thickness of several 1t772 can have a considerable influence on the loss of information recording and reproduction. Therefore, in the case of the optical disc of this embodiment, the liquid photocurable adhesive is applied to the recording medium 7 with a roughness of 0.2 μm immediately before use so as to contain no foreign matter with a laser beam spot diameter of 1 μm or more. It was purified by filtration and used. The error rate during recording and reproduction of the optical disc created in this manner was reduced by about two orders of magnitude compared to that of the optical disc created using the conventional method.

That is, the optical disc of this embodiment is characterized in that a photocurable resin adhesive layer 6 that can prevent the inclusion of foreign matter is formed in the vicinity of the recording medium 7 where the presence of foreign matter should be extremely reduced.

Note that if the thickness of the photocurable adhesive 7 is less than 50 μm, the error rate will be worse by one order of magnitude or more, and if it is more than 200 μm, it is actually difficult to maintain the adhesive layer 6 at a uniform thickness and bond it to the protective resin plate 5. The thickness of the photo-curing adhesive 7 is 6.5 mm because the optical path length of the laser beam is different for each part of the optical disk.
0~200μ? A range of n is optimal.

Comparative Example In order to compare the characteristics of the optical disc of Example 1, the experimental results of this comparative example will be described. When the original disk is created by the conventional method shown in Fig. 1, that is, a grooved optical disk base 1 is molded from transparent polycarbonate resin, acrylic resin, etc., and a tellurium oxide recording medium is formed on its surface under the same conditions as in f111. 7'ff: A transparent protective plate 8 was bonded with the same photocurable adhesive 6 as in Example 1 to prepare an optical disc, and recording and reproduction were performed by the method shown in FIG. As a result, the error rate was ax1o' in the case of the polycarbonate resin substrate, and 3×10 2 in the case of the acrylic resin substrate. For reference, there are 50,000 foreign particles with a diameter of 0.21N77 or larger in 1 gram of the polycarbonate resin used here, 1, and 3 in the acrylic resin.
, 80,000 were observed.

Embodiment 2 The original disk having the structure of the present invention and its manufacturing method are not limited to an optical disk with grooves on one side, but can also be applied to an optical disk with grooves on both sides. FIG. 4 shows an actual example of an optical disc with grooves on both sides. In the figure, reference numeral 8 denotes a resin disk substrate with grooves on both sides obtained by compression or injection molding, and a tellurium oxide recording medium is adhered to both sides of the groove surface by any method such as vapor deposition. After that, the surface of the recording medium is transparent and has a roughness of 0.2.
Photocurable adhesive 7 purified through μ277 filter? L and Tb are applied to both sides with a uniform thickness of 50 to 200 μm, and transparent protective resin plates 6a and 6b are applied on top of this.
An optical disk capable of double-sided recording and reproduction was obtained by superimposing each of f and y and irradiating the entire surface with ultraviolet rays. Regarding recording and reproduction of this optical disc, Example 1 and All 1 are described.

The same method was used.

Effects of the Invention As is clear from the above explanation, due to its structure, conventional optical discs are susceptible to the influence of foreign matter present in the resin when recording and reproducing information, resulting in a fairly high error rate. However, with the optical disc and its manufacturing method of the present invention, the error rate has been improved by about two orders of magnitude compared to conventional optical discs.
It is now possible to achieve 18x10 to 3x165,
It is extremely effective in making optical discs smaller and increasing their capacity and reliability.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the structure of a conventional optical disc and a recording/reproducing method using it, Fig. 2 is a sectional view of an original disc according to an embodiment of the present invention, and Fig. 3 is a diagram showing a recording/reproducing method of the optical disc. The figure shown in FIG. 4 is a sectional view of an optical disk according to another embodiment of the present invention. 5, 52L, 5 b-=-protective resin plate, 6.6a
, 6b...photocurable adhesive layer, 7.7a, 7
b...Recording medium, 8...Protection plate.

Claims (1)

[Claims] (1) Optical recording that covers at least the surface of a grooved resin substrate and the grooves from the side opposite to the irradiation direction of the optical signal (6)
a medium layer; a photocurable adhesive covering the optical recording medium layer;
An optical disc comprising a light-transmitting resin layer covering the photocurable adhesive and sequentially arranging the light-transmitting resin layer. 3. (2) The optical disc according to claim 1, wherein the photocurable adhesive does not contain foreign matter of 0.2 μm or more.
(3) The optical disc according to claim 1, wherein the photocurable adhesive layer has a uniform thickness of 50 to 200 μn2. (4) A method for manufacturing an optical disc, which comprises the steps of molding a grooved resin optical disc substrate by injection molding or compression molding, and stacking a protective resin plate on the substrate and bonding it by irradiating it with ultraviolet rays. . 5. The method of manufacturing an optical disk according to claim 4, wherein a photocurable adhesive that has been purified so as not to contain foreign matter of 0.2 μm or more is used. 5. The method of manufacturing an optical disk according to claim 4, wherein the thickness of the photocurable adhesive is 50 to 200 μm.