JPH0246540A - Optical disk - Google Patents

Abstract

PURPOSE:To improve productivity and to reduce cost by constituting the optical disk of a 1st substrate on which a recording layer is formed and the 2nd substrate which consists of a light transparent material and constituting at least either of the 1st substrate or 2nd core block of a flat part and side wall part which are continuously and integrally molded. CONSTITUTION:The surface of a plastic sheet 8 is coated with a signal forming layer 9 which is the recording layer and signals are transferred thereon by pressure transferring of sputters. A metallic film layer 10 is provided by vapor deposition, etc., on the signal forming layer 9 and a signal surface 11 of information pits, etc., is formed to incorporate the 1st substrate 12. The 2nd substrate 14 formed by subjecting plastic to sheet molding by hot molding such as vacuum molding and pressure molding or cold molding such as compression molding or non-heat pressure molding is provided via an air layer 13 on the reading out surface side of the 1st substrate 12. The productivity is improved in this way and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a read-only optical disc, and particularly to an optical disc that can improve productivity and reduce costs.

[Prior Art] Optical recording has advantages over magnetic recording in that there is no contact between the recording medium and the head, and high-density recording is possible. As this optical recording medium, there are known read-only ones, additionally writable ones, erasable and rewritable ones, and the read-only optical recording medium (hereinafter referred to as an optical disk) according to the present invention. )as,
It has already been put into practical use in the form of compact discs and optical video discs.

FIG. 7 is a cross-sectional view schematically showing an example of an optical disc manufactured by a conventional manufacturing method.

That is, a base material 1 is created by injection molding or the like, and a metal film layer 2 is formed on this base material 1 by a method such as vapor deposition or sputtering.
will be established. Further, a protective coat layer 3 is applied on this metal film layer 2, and a label printing 4 is applied thereon. Note that 5 indicates the center hole of the disk, and 6 indicates the signal surface such as information pits.

[Problems to be Solved by the Invention] By the way, conventional optical discs are manufactured by molding discs by injection molding or the like as described above, and then applying vapor deposition, protective coating, printing, etc. to each disc. must be carried out. Therefore, expensive production equipment is required and the product price is high. In addition, the productivity of the disk is low, making it unsuitable for mass production. That is, although a certain degree of mass production can be expected, there is a limit, and it is not particularly suitable for mass production on the scale of publications such as magazines and books, and material costs and equipment depreciation costs are high.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide an optical disc that is extremely inexpensive and has high productivity.

[Means for Solving the Problems] In order to achieve the object described above, the present invention provides a read-only optical disc comprising a first substrate on which a recording layer is formed and a light-transmitting material. , and a second substrate provided on the readout surface side of the first substrate with an air layer in between.
At least one of the substrate and the second substrate is composed of a flat portion and a side wall portion that are continuously integrally molded.

[Function] Therefore, in the optical disc of the present invention, it is possible to improve productivity and lower the price compared to discs made by conventional injection molding or the like.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view schematically showing a configuration example of an optical disc according to the present invention. In FIG. 1, a signal forming layer 9, which is a recording layer, is coated on the surface of a plastic sheet 8 whose back surface has been previously subjected to label printing 7, and a signal is transferred by suppressing sputtering and transferring. Further, a metal film layer 10 is provided on the signal forming layer 9 by vapor deposition or the like, except for the inner and outer circumferential portions of the disk, to form a signal surface 11 such as information pits. In addition, if necessary, on the signal surface 11,
A thin protective layer may be applied. As described above, the first substrate 12 is configured. Here, the material of the plastic sheet 8 is generally a thermoplastic resin such as polyamide, polyester, polycarbonate, polymethyl methacrylate, methylpertene resin, ionomer resin, polyether sulfone, vinyl chloride,
In addition to polystyrene, cellulose resins, etc., polyolefins such as polyethylene and polypropylene can also be used, and these can be stretched or laminated.

They can be used by laminating them to have the required composition by coextrusion or the like. Furthermore, these resins, paper, metal film thickness, etc. may be laminated and used.

Furthermore, in this embodiment, a plastic sheet is formed on the readout surface side of the first substrate 12 through an air layer 13 by hot forming such as vacuum forming or pressure forming, or by cold forming such as compression forming, or by non-conductive forming. A second substrate 14 is provided which is formed into a sheet by heating and pressing. That is, the second substrate 1
4 is hermetically coupled to the signal forming layer 9 of the first substrate 12 at the inner circumferential portion 15 and outer circumferential portion 16 of the disk.

(However, if there is a drastic change in the outside temperature, or if the internal gas expands or condenses, it is okay to provide small holes in areas that do not interfere with signal reading.) Here, the connection between the two As a method, select a method of thermocompression bonding using a seal such as heat seal or fusion seal, or a method of bonding by applying an adhesive such as glue, Hot Mate, ultraviolet curing resin, or ordinary solvent-based adhesive, etc. . Furthermore, as the material for the second substrate 14, it is appropriate to use a thermoplastic resin with good light transmittance, such as vinyl chloride resin.

polyamide, polyester, polycarbonate.

Polymethylmethacrylate-1-, methylpertene resin.

Examples include ionomer resin, polyether sulfone, polyphenylene sulfide resin, and the like. Note that 17 indicates the center hole of the disk.

In the optical disc having such a configuration, the first substrate 1
2 and a second substrate 14, the second substrate 14 is
Because the plastic sheet is formed by cold forming such as vacuum forming, pressure forming, compression molding, or non-heating suppression molding, the productivity of the disc is higher than that by conventional injection molding, etc., making it suitable for mass production. It's suitable. In addition, production equipment is inexpensive and product prices are low. Furthermore, the first
Since the air layer 13 is formed between the substrate] 2 and the second substrate X4, the thickness of the second substrate 14 can be made thinner by that amount, and the material cost can be reduced. . Furthermore, it is especially suitable for small-sized discs such as 8 cm compact discs.

As described above, the optical disc of this embodiment is made of a first substrate 12 on which a recording layer is formed and a translucent material. Vacuum forming, pressure air forming.

The second product consists of a sheet molded product by cold forming such as compression molding.
Since the second substrate 14 is composed of a flat part and a side wall part which are continuously and integrally molded,
This makes it possible to create an optical disc that is extremely inexpensive, highly productive, and ideal for small-sized discs.

It should be noted that the present invention is not limited to the two consecutive embodiments, but can be implemented in the same manner as follows.

(a) FIGS. 2 and 3 are a sectional view and a plan view showing other embodiments of the optical disc according to the present invention, and the same parts as in FIG. This will be omitted and only the different parts will be described here. That is, in this embodiment, the first substrate 12 in the second substrate 14
A concave portion 14a is provided intermittently in a portion corresponding to the central portion of the disk where the signal surface 11 is not provided, and the first substrate 1
2 and the second substrate 14 are coupled and connected at the inner circumference 15 and outer circumference 16 of the disk, and are brought into contact with each other at the recess 14a.

In this case, the concave portion 14a does not need to be adhesively bonded, unlike the bonding portion between the inner circumferential portion 15 and the outer circumferential portion 16 of the disk, and may be in contact with the first substrate 12. The first substrate 12 may be adhesively bonded to the first substrate 12 by a method such as the like, and stability during signal reproduction can be improved. Further, by providing the recess 14a, the distance between the first substrate 12 and the second substrate 14 can be maintained constant, and it is possible to prevent signals from becoming difficult to read due to distortion, waviness, etc. of the second substrate 14. It can be prevented. Note that the shape of the recess 14a is not limited to the shape shown in the figure;
For example, circular, square, rectangular.

It may be a polygon such as a triangle, and is not limited in any way. Furthermore, in this embodiment, the connecting portion between the inner circumferential portion 15 and the outer circumferential portion 16 of the disk has a shape different from that in FIG. 1, but it may have a topographical shape such as the shape shown in FIG. 2 without any problem.

(b) FIG. 4 is a sectional view showing another embodiment of the optical disc according to the present invention, and the same parts as in FIG. I will only describe the parts. That is, in this embodiment, the first substrate 1
2 and the second substrate 14, a spacer 18 is provided at an inner peripheral portion than the signal surface 11. According to this embodiment, the distance between the first substrate 12 and the second substrate 14 can be regulated more accurately. Note that in this embodiment, the spacer 18 was provided on the inner circumference of the signal surface 11;
The signal surface 11 may be formed closer to the center of the disk than the illustrated position, and the spacer may be provided on the outer periphery of the signal surface 11. Furthermore, although spacers may be provided on both the inner and outer peripheries, it is necessary to provide side walls on either or both of the inner and outer peripheries.

(c) FIG. 5 is a sectional view showing another embodiment of the optical disc according to the present invention. The same parts as in FIG. I will only talk about. That is, in this embodiment, the first substrate 1
2 is constructed by molding a plastic sheet into a sheet by cold molding such as vacuum molding, pressure molding, compression molding, or non-heating suppression molding. in this case,
The stamper can suppress and transfer the signal and simultaneously mold the outer periphery, but of course the plastic sheet 8 can also be molded.
．． Alternatively, a plastic sheet 8 coated with the signal forming layer 9 may be molded in advance, and the signal may be suppressed and transferred onto the plastic sheet 8 using a stamper.

(d) FIG. 6 is a cross-sectional view showing another embodiment of the optical disc according to the present invention. The same parts as in FIG. I will only talk about. That is, in this embodiment, the first substrate 1
2 and the second substrate 14 are formed by molding plastic sheets into sheets by cold molding such as vacuum molding, pressure molding, compression molding, or non-heating suppression molding.

(e) In FIGS. 1 to 6, the first substrate 12, the second substrate
A case has been described in which the substrate 14 is formed by molding a plastic sheet by cold molding such as vacuum molding, pressure molding, compression molding, or non-heating suppression molding, or at least one of the substrates is created by injection molding or the like. There is no harm in doing so. In this case, a disk with an air layer without a spacer? LJ, and the second substrate 14 can be made even thinner.

(f) It goes without saying that in each of the embodiments shown in FIGS. 1 to 6 above, light attenuation can be reduced by applying an antireflection coating to the inside and outside of the second substrate 14.

(g) Regarding the thickness of the optical disc of the present invention, please refer to the second
The distance between the substrate 14 and the objective lens of the reader (player) and the objective lens of the reader (player) for focusing may be any distance provided that they do not collide with each other even if they move, and the thickness of the conventional compact disc is 1. 2+no
It can also be made thinner than +.

(h) In the present invention, it is also possible to suppress and transfer signals directly to the plastic sheet 8 with a stamper, but when providing the signal forming layer 9, in addition to thermoplastics,
Ultraviolet curable resins, electron beam curable resins, etc. can also be used.

(i) In the present invention, the structure and manufacturing method of the first substrate 12 are not limited to those described above, and for example, signals are transferred directly onto the plastic sheet 8 by pressure transfer without using the signal forming layer 9. It may also be formed.

[Effects of the Invention] As explained above, according to the present invention, the first substrate is made of a light-transmitting material and has a recording layer formed thereon. Since at least one of the first substrate and the second substrate is composed of a flat portion and a side wall portion that are continuously integrally molded, production is extremely inexpensive. We can provide optical discs that are ideal for small, highly sensitive discs.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the optical disc according to the present invention, FIGS. 2 and 3 are cross-sectional views and plan views showing other embodiments of the optical disc according to the present invention, and FIGS. FIG. 6 is a sectional view showing other embodiments of the optical disc according to the present invention, and FIG. 7 is a sectional view showing an example of a conventional optical disc. 7...Siebel printing, 8...Plastic Sea I...
9... Signal forming layer, 10... Metal film layer, 11...
Signal surface, ] 2... First substrate, 13... Air layer, 1
4... Second substrate, 15... Disk inner peripheral part, 16
... disk outer circumference, 17 ... center hole of disk,
18...Spacer. Applicant's agent Patent attorney Takehiko Suzue

Claims (3)

[Claims] (1) A read-only optical disc includes a first substrate on which a recording layer is formed, and a second substrate made of a transparent material and provided on the read-out surface side of the first substrate with an air layer interposed therebetween. 1. An optical disc comprising: two substrates, wherein at least one of the first substrate and the second substrate comprises a flat portion and a side wall portion that are continuously and integrally molded. (2) At least one of the first substrate and the second substrate is formed of a sheet molded product by hot forming such as vacuum forming or pressure forming or cold forming such as compression forming. The optical disc according to item 1. (3) The optical system according to claim 1, wherein the second substrate has recesses provided intermittently in a portion corresponding to a central portion of the first substrate where the signal surface is not provided. formula disc.