JPS6180630A - Reflected light disc and its manufacture - Google Patents

Abstract

PURPOSE:To improve the reliability and productivity by forming a reflecting film only on each recording area of transparent bases opposed to each other, adopting transparency to the other parts and bonding the transparent parts to attain reproduction of both sides. CONSTITUTION:Signal pits are engraved on one side of transparent bases 1, 1' except the surrounding of a center hole 5 and circumferences of the bases 1, 1'. The signal pit engraved parts 2, 2' of each base are formed with the reflecting film formed on the surface of recording area only and with the transparent film except the recording area. Protecting films 3, 3' are formed on the reflecting films 2, 2' of each base and both are adhered closely without an adhesives. The layer 4 of the adhesives is applied only to the transparent parts to bond the two bases and as the adhesives, an adhesives of ultraviolet curing type is used. Since the adhesives has a large bonding strength and longer pot life, the alignment of adhesion of the bases is conducted easily and the performance of work is attained easily, and the adhesives inserted to the transparent parts is cured easily by irradiating light from the parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reflective optical disk and a method for manufacturing the same, and more particularly to a reflective optical disk with high reliability and a method for manufacturing the same with high productivity.

[Technical background of the invention and its problems 3 The reflective optical disc is LV Nostem fLaser V
onSystem), and conventionally a structure as shown in FIG. 21ζ has been widely used.

For example, the No. 48 pits engraved on one side of each transparent base 491.1', such as acrylic resin, are covered with a reflective film 2°2', such as a thin aluminum film, over the entire surface,
Furthermore, organic protective films 3 and 3' such as ethylene vinyl acetate, acrylic resin, and Evoquin resin are formed on each reflective film, and both are bonded together with an adhesive 4. 5; Yo,
This is the center hole of the disc. When reading information, a laser beam is focused and irradiated with a lens from the back surface of the substrates 1 and 1', and the same lens picks up the reflected light modulated by the bits engraved on each substrate.

In the manufacture of such reflective optical discs, the adhesive used in the bonding process of bonding two substrates has traditionally been Cemfin 5F5. TiB agents such as Cemedine 110 and 5C210; Evokin-based agents such as Debcon WR and Aralleguit AW106; Snowbond 2001; or Thermogrip 9880A.

Thermogrid 7'TCL-130, Evaflex 41
0.560. Hot melt type products such as PSO7 are widely used.

However, both of the former two types of adhesives have a corrosive effect on substrates made of synthetic resin and reflective films such as aluminum films, and they also take a long time to harden, which improves productivity. There are problems in that it has an adverse effect on the adhesive strength and the adhesive strength itself is not that great. In addition, hot melt type products have a short pot life, making it difficult to smoothly align both substrates after coating the protective film, which can easily cause misalignment between the two, and require expensive coating equipment. Requires. Furthermore, those with a low melting point have low adhesive strength at room temperature. In order to increase the adhesive strength between both substrates, a hot-melt type material with a fairly high melting point may be used, but in that case, it is necessary to heat the substrates themselves.

As a result, thermal deformation such as warpage occurs in the substrate, and vibration of the disk occurs when the recording/reproducing source rotates.
Become. Furthermore, since this type of adhesive generally has a high viscosity, the thickness of the adhesive layer becomes thicker than necessary, and there is also the problem that it is difficult to achieve accuracy in overall flatness when both substrates are bonded together.

Furthermore, the reflective optical disk having the structure shown in FIG.
Since the adhesive is bonded via the reflective film 2 and the protective film 3, which are formed over the entire surface of one side, the mutual adhesion on all these film surfaces is not necessarily homogeneous. Therefore, its reliability as a reflective optical disc could not necessarily be said to be high.

[Purpose of the invention]

An object of the present invention is to provide a reflective optical disc having a PR-like structure different from the conventional one, and a method for manufacturing the same.

[Summary of the invention]

The reflective optical disc of the present invention is characterized in that a reflective film is formed only in each recording area of the opposing light-transmitting substrates, and the other parts are light-transmitting. A reflective film is formed only on the recording area of the transparent substrate, and then 1 Cci! , after forming a protective film, make them face each other,
It is characterized in that the reflective film and the light-transmitting portion on which the protective film is not formed are bonded and integrated with an adhesive.

A side view 1 illustrating the reflective optical disc of the present invention in FIG.
This will be explained in further detail based on 0.

In FIG. 1, 1 and 1' are transparent substrates made of synthetic resin such as acrylic resin, as in the prior art. Signal bits are engraved on one side of the substrates 1, 1'. The figure shows an example in which the signal bits are engraved around the central hole 5 of the substrates [1, 1' and excluding the peripheral edges of the substrates 1, 1'.

Reference numeral 2.2' denotes a reflective film formed only on the surface where signal bits are engraved on each substrate, that is, on the surface where recording is distinguished. Therefore, the portion other than the recording area exists as a transparent portion.

3 and 3' are protective films formed on the reflective films 2 and 2 of each substrate, and both are in close contact with each other without using an adhesive.

Reference numeral 4 denotes an adhesive layer, which is applied only to the above-mentioned translucent portion to bond the two bases together. The adhesive is preferably a translucent photo-curable adhesive, particularly an ultraviolet-curable adhesive. Such adhesives include, for example, TB
30.60 (ThreeBond), Chemitite CT-40
0-5G (Toshiba Chemical Company), Amicono UV Freeze (Amicon Company), Hordebond (Myojo Churchill Company),
It is possible to list products such as Loctite 352, 358 (Nihon Lokkui!-sha).

These adhesives have high adhesive strength and a long pot life, making it easy to perform positioning work when bonding substrates together, and are highly workable. Even if the above-mentioned adhesives were used in the conventional reflective optical disk shown in FIG. 2, the adhesives could not be photocured because the reflective film was present on the entire surface.

However, in the case of the structure of the present invention illustrated in FIG. 1, it becomes possible to easily cure the adhesive interposed in the transparent portion by irradiating light from the transparent portion.

The reflective optical disc of the present invention can be manufactured as follows.

First, a reflective film of, for example, aluminum is formed to a predetermined thickness only on the recording area carved on one side of each of the two light-transmitting substrates by applying a vacuum evaporation method or a sputtering method. Then, epoxy resin is applied onto the reflective film using, for example, a screen printing method.

A protective film of a predetermined thickness such as acrylic resin is formed.

Thereafter, a photocurable adhesive is applied to the light-transmitting portion other than the recording area by, for example, screen printing.

Next, after bonding the two substrates together and positioning them accurately, light energy (ultraviolet rays) of a predetermined wavelength is irradiated from the back side of the substrates 1 and 1' to photocure the adhesive present in the transparent portions. In this way, a reflective optical disc capable of double-sided playback is formed.

[Embodiments of the invention]

It is a disc with an outer diameter of 300 m, a center hole diameter of 35 + III m, and a thickness of 12 m, with signal pits carved from 110 to 290 - from the center (width of recording area 90 m).
Four disks made of acrylic resin were molded by injection molding.

Two of these sheets were covered with two wedges of nickel donut plates with a thickness of 0.3 mm to mask areas other than the recording area.
Approximately 10 mm thick using vacuum evaporation method at a pressure of 5 x 10-6 Torr.
An aluminum thin film of 0.000 people was deposited. For the remaining two sheets, an aluminum thin film with a thickness of about 100 ml was formed on the entire surface under the same conditions as above without using a mask material.

The mask material was removed from the previous two sheets, and a protective film (Guicure Clear 5DI) with a thickness of approximately 10 μm was placed on the formed aluminum film.
7: manufactured by Dainippon Ink Co., Ltd.) was formed using a screen printing method. Similar protective films were also formed on the two comparative examples.

An ultraviolet curable adhesive (TB-3
060, ThreeBond M) to a thickness of about 15 μm, and after adhering and positioning the coated surfaces facing each other, apply ultraviolet rays from a high-pressure mercury lamp with a wavelength of about 250 to 400 nm and an output of 4 KW to the back of the disk. Scanning irradiation was performed from

The adhesive cured in about 8 seconds. The total working time was 2-3 minutes. No deformation such as warpage was observed in the obtained reflective optical disc.

On the other hand, a hot-melt type [1 agent (PS-0
7, A, C, manufactured by 1 company) was applied to a thickness of about 30 μm.

The roll temperature was 120°C.

After coating, the coated surfaces were immediately bonded together. The total working time, including the time for melting the adhesive, was about 23 minutes.

In addition, although the obtained reflective optical disk had eccentricity within the standard, the present invention allowed sufficient time and positioning with higher accuracy. Further, a warpage of approximately 0.5+++m was observed between the center and the periphery.

〔Effect of the invention〕

As is clear from the above description, the reflective optical disk of the present invention has a structure that allows use of an ultraviolet curable adhesive that has high adhesive strength, is easy to bond, and has a short curing time. Therefore, the reflective optical disc of the present invention retains signal bits with high precision, can be reproduced on both sides, and has high reliability1.Also, since the curing time of the adhesive is short, the manufacturing method thereof has high productivity. Terro. Furthermore, since this adhesive has a lower viscosity than conventional adhesives (for example, hot melt type), the thickness of the coating layer can be reduced, which can also contribute to reducing the weight of the entire disc.

Furthermore, from the standpoint of the disc user, it has the advantage that the recorded area can be easily determined by visual inspection.

[Brief explanation of the drawing]

FIG. 1 is a side view of a reflective optical disk according to the present invention, and FIG. 2 is a side view of a reflective optical disk having a conventional structure. 1.1' - Transparent substrate 2,2' Reflective film 3.3
' Protective film 4 - Adhesive 5 ・Disk center hole Figure 1 Figure 2 Procedural amendment September 10, 1985 Michibe Uga, Commissioner of the Patent Office 1 Indication of the case Patent Application No. 201963 of 1988 2, Name of the invention: Reflective optical disc and its manufacturing method 3; Relationship with the case of the person making the amendment Name of patent applicant (3071 Toshiba Corporation 4; Agent 5; Date of amendment order: Self-initiated 6; Subject of the amendment: Mei! A) Column 7 for detailed description of the invention;
Contents of the amendment: "Record classification" stated on page 5, line 15 of the specification is corrected to "record area."

Claims (1)

[Scope of Claims] 1. A reflective optical disc characterized in that a reflective film is formed only in each recording area of opposing light-transmitting substrates, and the other parts are light-transmitting. 2. After forming a reflective film only in the recording area of two light-transmitting substrates, and then forming a protective film on the reflective film, the two are placed facing each other, and the reflective film and the protective film are formed. A method for producing a reflective optical disc, which comprises bonding and integrating non-transparent parts with an adhesive. 3. The method according to claim 2, wherein the adhesive is an ultraviolet curable adhesive.