JPH0229949A - Information recording medium - Google Patents

Abstract

PURPOSE:To allow good fusion joining by joining two sheets of disk-shaped substrates via annular spacers provided on the inner and outer sides thereof and adjusting the joining position of the spacer and substrate on the outer side to the inner side by a specific size from the outer peripheral part of the substrates. CONSTITUTION:Two sheets of the disk-shaped substrates 11a, 11b with recording layers 22a, 22b positioned on the inner side are joined to each via the inner and outer annular spacers 12, 13. A notch is so provided and formed to the outer spacer 13 that the contact positions of the spacer 13 and the substrates 11a, 11b exist inner within a >=0.1mm and within 1.5mm range from the outer peripheral part of the substrates. The nonuniform contact with bulging parts 23a, 23b formed along the outer peripheral part of the substrates 11a, 11b is, therefore, obviated. Two sheets of the substrates are well fusion-joined in this way and the recording characteristics of the recording layer are stabilized over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention 1] The present invention relates to the improvement and improvement of an information recording medium having an air sandwich structure in which two disc-shaped resin substrates are joined.

[Technical Background of the Invention] In recent years, information recording media using high energy density beams such as laser beams have been developed and put into practical use. This information recording medium is called an optical disc, and includes video discs, audio discs, large-capacity still image files, and large-capacity computer discs.
It can be used as memory.

The basic structure of an optical disk is a disc-shaped transparent resin substrate made of plastic or the like, and a recording layer provided thereon. The surface of the substrate on which the recording layer is provided is coated with an undercoat layer or an intermediate layer made of a polymeric material in order to improve the flatness of the substrate, improve the adhesion with the recording layer, and improve the sensitivity of the optical disc. Sometimes it is provided.

Various types of optical discs are known, but in recent years, air sandwich structures in which the substrate is bonded with the recording layer on the inside through inner and outer ring-shaped spacers have become common. ing. As a method for manufacturing an optical disk, a method has been proposed in which a resin substrate and inner and outer ring-shaped spacers are fused and bonded using an ultrasonic fusion bonder (for example, Japanese Patent Laid-Open No. 103537/1983).

By the way, resin substrates for information recording media are generally manufactured by a molding method such as injection molding.According to the inventor's study, due to the structure of the mold, In the obtained resin substrate, protrusions (burrs) and uneven bulges of about 10 gm were observed along the outer peripheral edge on the side where the recording layer was not provided. Furthermore, although protrusions are not often seen on the side where the recording layer is provided, bulges with a height of around 104 m are often unevenly formed along the outer periphery. There was found.

The attached FIGS. 7A and 7B are diagrams showing the relationship between the distance from the outer periphery of the bulge formed on the outer periphery of the resin substrate on the side where the recording layer is provided and the height, as measured by the inventor. be. As shown in FIG. 7A, a bulge 72a
is formed at a height of approximately 11 pm from a distance of approximately 1.0 mm from the outer peripheral edge of the resin substrate to the outer peripheral edge. Further, in another example of a molded substrate, as shown in FIG.
．． It is formed at a height of approximately 9 pm from a distance of 1 mm to the outer peripheral edge. Further, even within the same substrate, such bulges exist with irregularly varying radius and height.

According to studies by the inventors, bulges and protrusions (
It has been found that when an optical disc is manufactured by an ultrasonic fusion method or the like using a resin substrate on which a resin substrate is formed, the optical disc tends to not exhibit the expected characteristics.

Incidentally, as for the bumps that tend to occur on the side of the substrate where the recording layer is not provided, the protrusions can be eliminated by using a method for manufacturing information recording media (Japanese Patent Application No. 71249/1983) that the present inventors have already applied for. (Paris) etc. can be extremely effectively prevented from occurring on information recording media.

As a result of further investigation into the problem of the bulge in the outer peripheral edge as shown in FIGS. 7A and 7B, the present inventor found that an unexpected contact state between the outer ring-shaped spacer and the resin substrate caused the optical disc to It was found that this hinders stable production.

Here, referring to the attached FIG. 6, two resin substrates having non-uniform bulges formed on the outer periphery of the recording layer side of the substrates as described above were prepared according to the prior art. Problems in ultrasonic fusion bonding will be explained.

In FIG. 6, two disc-shaped resin substrates 61a, 61
b are overlapped via the inner ring-shaped spacer 62 and the outer ring-shaped spacer 63, and the disk-shaped ultrasonic application horn 65 and disk-shaped receiver of the ultrasonic fusion machine 64 are arranged between the jig 66. ing. The ultrasonic fusion splicer 64 uses ultrasonic energy oscillated from an ultrasonic oscillator 67 to
8 to reach the ultrasonic applying horn 65.

The resin substrates 61a and 61b each have a hole 69a in the center.
, 69b, and inner non-recording areas 70a, 70b and outer non-recording areas 71a, 71b are provided outside the peripheral edges of the holes 69a, 69b and inside the outer peripheral edges of the resin substrates 61a, 61b, respectively. Recording layers 72a and 72b are formed between the respective non-recording areas.

Non-uniform bulges 73a and 73b are formed on the outer peripheral edges of the resin substrates 61a and 61b on the side of the recording layer.

Each ring-shaped spacer 62, 63 is formed with a ring-shaped protrusion 74, 75, respectively. The inner ring-shaped spacer 62 is arranged to correspond to the non-recording areas 70a and 70b on the inner circumferential side of the resin substrates 61a and 61b, and the outer ring-shaped spacer 63 is arranged to correspond to the non-recording area 71a on the outer circumferential side. .

71b.

Each non-recording area 70a of each ring-shaped spacer 62, 63,
The fusion bonding at 70b, 71a, and 71b is performed by bringing the ultrasonic application horn 65 into contact with a position corresponding to each ring-shaped spacer 62, 63 on the surface of the resin substrates 61a, 61b, and applying ultrasonic energy. , two resin substrates 61a
, 61b with the recording layers 72a, 72b facing inside, and are fusion-bonded via ring-shaped spacers 62, 63.

However, uneven bulges 73a are formed toward the outer spacer side along the outer peripheral edges of the resin substrates 61a and 61b on the recording layer side.
, 73b, the contact between the outer spacer and the surfaces of the resin substrates 61a, 61b will not be uniform, and therefore the application of ultrasonic energy will not be uniform either.

Therefore, the strength of the fusion bond between the resin substrates 61a, 61b and the outer ring-shaped spacer 63 becomes uneven, and uneven bonding is likely to occur. Therefore, there is a problem in that the outer ring-shaped spacer 63 is likely to peel off from the resin substrates 61a, 61b.

Furthermore, for the reasons mentioned above, optical discs manufactured using the conventional method described above suffer from warping and distortion in addition to uneven bonding.
Dimensional performance may deteriorate.

Then, surface runout during rotational driving and fluctuations in the birefringence of the resin substrate may occur.

Furthermore, it is not easy to obtain a resin substrate with almost no bulges by a molding method, and in order to obtain such a resin substrate, special consideration must be given to the molding conditions.
This is disadvantageous because the manufacturing cost increases.

[Object of the Invention] An object of the present invention is to provide an information recording medium having an air sandwich structure in which two resin substrates are well bonded.

[Summary of the Invention] When two resin substrates are fusion-bonded, the inventor has investigated the influence on the fusion-bonding of a bulge formed during resin molding on the outer peripheral edge of the substrate on the side where the recording layer is provided. As a result of focusing on the above and conducting studies, the present invention has been completed.

The present invention provides an air sandwich structure in which two disc-shaped substrates, at least one of which has a recording layer, are joined with the recording layer inside through an inner ring-shaped spacer and an outer ring-shaped spacer. An information recording medium.

The contact position between the outer peripheral edge of the outer ring-shaped spacer and each substrate is 0.1 mm from the outer peripheral edge of the recording layer side surface of each substrate.
The information recording medium is characterized in that it is located inside within a range of 1.5 mm or less.

Note that preferred embodiments of the present invention are as follows.

(1) The above information characterized in that the contact position between the spacer and the substrate is inside a position within a range of 0.5 to 1.0 mm from the outer peripheral edge of the recording layer side surface of the substrate. recoding media.

[Detailed Description of the Invention J The method for manufacturing the information recording medium of the present invention basically consists of ultrasonic welding of two conventional resin substrates shown in FIG.
Bonding equipment is available. However, the information recording medium of the present invention eliminates the drawbacks of the conventional information recording medium, and a method for manufacturing the same will be described in detail with reference to FIGS. 1 to 5 attached hereto.

In FIG. 1, two disc-shaped resin substrates 11a, 11
b are overlapped via the inner ring-shaped spacer 12 and the outer ring-shaped spacer 13, and the disk-shaped ultrasonic application horn 15 and disk-shaped receiver of the ultrasonic welding a14 are arranged between the jig 16. There is. The ultrasonic fusion splicer 14 transmits ultrasonic energy oscillated from the ultrasonic oscillator 17 to the converter 1.
The ultrasonic wave application water is configured to reach an ultrasonic application water tube 15 via a water tube 8 .

The resin substrates 11a and llb each have a hole 19a in the center.
, 19b, and inner non-recording areas 20a, 20b and outer non-recording areas 21a, 21b are provided outside the periphery of the holes 19a, 19b and inside the outer periphery of the resin substrates 11a, llb, respectively. Recording layers 22a and 22b are formed between the respective non-recording areas.

Non-uniform bulges 23a, 23b are formed on the outer peripheral edges of the m-fat substrates 11a, llb on the side of the recording layer.

Each ring-shaped spacer 12.13 is formed with a ring-shaped protrusion 24.25. The inner ring-shaped spacer 12 is arranged so as to correspond to the non-recording areas 20a, 20b on the inner peripheral side of the resin substrates 11a, 11b,
The outer ring-shaped spacer 13 is a non-recording area 2 on the outer circumferential side.
1a and 21b.

A cross-sectional view of the outer ring-shaped spacer of the present invention is shown in FIG. 2. In FIG. 2, 25 is a ring-shaped projection, and upper and lower corner portions are cut out in the outer and inner directions of the spacer. 30 is a cloudy notch. Therefore, this notch 3
Since 0 is not fused, the outer peripheral edge of the recording side of the substrate and the outer spacer almost never come into direct contact even after the substrate and spacer are bonded.

Each non-recording area 20a of each ring-shaped spacer 12.13,
The fusion bonding at 20b, 21a, and 21b is performed by bringing the ultrasonic application horn 15 into contact with a position corresponding to each ring-shaped spacer 12, 13 on the surface of lla, 11b of the resin substrate, and applying ultrasonic energy. , two resin substrates 11a
, 11b with the recording layers 22a, 22b facing inside, and are fusion-bonded via ring-shaped spacers 12, 13.

FIG. 3 is a drawing showing the fusion-bonded information recording medium. Similar to FIG. 1 above, resin substrates 11a and 11b
have a hole 19a in the center.

19b, and inner non-recording areas 20a and 20b and outer non-recording areas 21a and 21b are set outside the periphery of the holes 19a and 19b and inside the outer periphery of the resin substrates 11a and 11b, respectively. A recording layer 22a, 22b is formed between each non-recording area. Non-uniform bulges 23a and 23b are formed on the outer peripheral edges of the resin substrates 11a and 11b on the side of the recording layer.

The fused portions of the inner ring-shaped spacer 12 arranged in the inner non-recording areas 20a and 20b with the resin substrates 11a and llb are 26a and 26b, and are arranged in the outer non-recording areas 21a and 21b. outer ring-shaped spacer 13
The fused portion with the resin substrate 11a and llb is 27a,
It is 27b.

As can be seen from FIG. 3, the outer ring-shaped spacer 13 has uneven bulges 23a and 23b on the outer peripheral edge of the substrate.
There is almost no contact even after the bonding, that is, the ultrasonic applying horn 15 is brought into contact with the positions corresponding to the ring-shaped spacers 12 and 13 on the surfaces of the resin substrates 11a and 11b, and ultrasonic energy is applied. When performing melt bonding, the outer ring-shaped spacer 13 is attached to the fused portions 27a and 27b.
Since it has the notch 30 that does not form a ridge, there is almost no uneven contact with the bulges 23a and 23b formed along the outer periphery.This allows the application of ultrasonic energy to the substrate and spacer. Each ring-shaped spacer 12.1
3 can be uniformly fused to the surfaces of the resin substrates 11a and llb.

The dimension D shown in FIG.
There are uneven bulges 23a and 23b on the outer peripheral edge on the recording layer side.
The dimension of the notch provided in the outer ring-shaped spacer 13 so as not to come into contact with .

FIG. 5 is an information recording medium manufactured according to the manufacturing method shown in FIG. 1, and shows another embodiment of the present invention.

The information recording medium shown in FIG. 5 is obtained by replacing the outer ring-shaped spacer 13 in FIG. 3 with an outer ring-shaped spacer 43 having a cross-sectional view shown in FIG.
The information recording medium shown in the figure is the same. Fourth
In the figure, 25 is a ring-shaped projection, and the upper and lower corners are notched only in the inner direction of the spacer. 30 is the notch.

The above FIG. 5 shows the resin substrates 11a and llb similarly to FIG.
are provided with holes 19a and 19b in the center, respectively, and hole 1
9a, 19b and the resin substrates 11a, l
A non-recording area 2 on the inner circumferential side is located inside the outer circumferential edge of the lb.
0a, 20b and outer non-recording areas 21a, 21b
are set, and a recording layer 22a is provided between each non-recording area.

22b is formed. Resin substrate 11a.

11b, there is an uneven bulge 23 on the outer circumferential twill portion on the side of the recording layer.
a, 23b are formed.

The fused parts 28a and 28b of the inner ring-shaped spacer 12 arranged in the non-recording areas 20a and 20b on the inner circumferential side and the resin substrates 11a and llb are arranged in the non-recording areas 21a and 21b on the outer circumferential side. outer ring-shaped spacer 43
The fused portion with the resin substrate 11a and llb is 29a,
It is 29b.

As shown in FIG. 5, this outer ring-shaped spacer 4
The uncut side wall of No. 3 faces outward. Then, there is an uneven bulge 23a on the outer peripheral edge of the recording side of the substrate.
and 23b, the uncut wall surface of the outer ring spacer 43 extends inward from the outer peripheral edge.

That is, the fused portions 29a, 2 between the outer spacer and the substrate
9b is an uneven bulge 23 on the outer peripheral edge of the recording side of the substrate.
It is located almost away from a and 23b.

Therefore, according to the manufacturing method shown in FIG.
When performing melt bonding by applying ultrasonic energy to the positions corresponding to the outer ring-shaped spacers 43, the bulges 23a, 23 are
There is almost no non-uniform contact with b, since ultrasonic energy can be uniformly applied to the substrate and spacer.

Each ring-shaped spacer 12.43 is connected to the resin substrate 11a, 1
It is possible to uniformly fuse the material to the surface of 1b.

The dimension E shown in FIG. 5 is the length of the uncut side wall surface of the outer spacer 13 extending inward from the outer peripheral edge, and may be within the range of 0.1-1.5 mm. necessary, preferably in the range of 0.5 to 1.0 mm.

The information recording medium of the present invention manufactured in this way (for example, FIGS. 3 and 5) has two resin substrates that are evenly and well fused together through the inner and outer spacers, and , excellent dimensional accuracy.

Separation between the ring-shaped spacer and the resin substrate does not substantially occur, and the recording characteristics of the recording layer are stabilized over a long period of time. Furthermore, since the obtained optical disc has excellent dimensional accuracy, there is little axial surface runout during disc playback, and the axial acceleration is extremely small.

Note that the method for manufacturing an information recording medium and the example of the information recording medium described in FIGS. 1 to 5 are in accordance with the present invention, but are not limited to the above examples.

For example, each of the inner and outer fusion bonding may be performed separately, with one fusion bonding being performed first.

Alternatively, one disk-shaped resin substrate may be fused and bonded to each of the inner and outer ring-shaped spacers.

As the substrate, spacer, and recording layer constituting the information recording medium of the present invention, any known substrate, spacer, and recording layer other than the characteristic configuration of the present invention can be used as desired, and these will be briefly described below.

The resin substrate can be arbitrarily selected from various resin materials conventionally used as substrates for information recording media. Optical properties and flatness of the substrate.

In terms of processability, handling, stability over time, and manufacturing cost, examples of substrate materials include cell-cast polymethyl methacrylate, injection molded polymethyl methacrylate, polymethyl acrylate, and other acrylic resins; polyvinyl chloride, chloride, etc. Vinyl chloride resins such as vinyl copolymers:
Preferred examples include epoxy resins; amorphous polyolefin resins; and synthetic resins such as polycarbonates. ``Among these, preferred are polymethyl methacrylate, polycarbonate, and epoxy resin in terms of dimensional stability, transparency, and flatness.

Each ring-shaped spacer used in the present invention includes:
Use one made of thermoplastic resin. By ultrasonic fusion method,
There is no particular limitation on the material as long as it can be well fused to the resin substrate. For the purpose of the present invention, it is particularly preferable to use the same material as the resin substrate material.

The surface of the substrate on which the recording layer is provided has improved flatness,
An undercoat layer (and/or intermediate layer) may be provided for the purpose of improving adhesive strength and preventing deterioration of the recording layer.

Examples of materials for the undercoat layer (and/or intermediate layer) include polymeric substances such as polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, nitrocellulose, polyethylene, chlorinated polyolefin, polypropylene, and polycarbonate; silane cups; Examples include organic substances such as ring agents; and inorganic substances such as inorganic oxides (Si02, A20, etc.) and inorganic fluorides (MgFz).

Examples of materials used for the recording layer include Te, Zn, I
n, Sn, Zr, An, Ti, Cu, Ge, Au, Pt
Semiconductors such as semimetal H3i such as Bi, As, and Sb; and alloys thereof or combinations thereof can be mentioned.

Compounds such as sulfides, oxides, borides, silicon compounds, carbides, and nitrides of these metals, semimetals, or semiconductors; and mixtures of these compounds and metals can also be used in the recording layer. Alternatively, combinations of dyes, dyes and polymers, and dyes and the aforementioned metals and metalloids can also be used.

The recording layer may further contain various known metals, semimetals, or compounds thereof as recording layer materials.

The recording layer can be formed on the substrate directly or via an undercoat layer by using the above-mentioned materials by vapor deposition, sputtering, ion blasting, coating, or the like. The recording layer may be a single layer or a multilayer, but its layer thickness is generally in the range of 100 to 5,500 OX, preferably in the range of 150 to 100 OX, in view of the optical density required for optical information recording.

Note that the surface of the substrate opposite to the side on which the recording layer is provided is coated with inorganic substances such as silicon dioxide, tin oxide, and magnesium fluoride to improve scratch resistance and moisture resistance.
A thin film made of a polymeric substance such as a thermoplastic resin or a photocurable resin may be provided by a method such as vacuum deposition, sputtering, or coating.Furthermore, the recording layer may be provided in a fused portion other than the recording area. You can leave it there.

[Effects of the Invention] The information recording medium of the present invention uses a spacer fusing method that secures a so-called relief part from the bulge of the resin substrate, so that even in a resin substrate where a bulge is formed,
During ultrasonic welding, the outer spacer can uniformly contact the surface of the resin substrate without almost contacting the bulge of the substrate. Therefore, in the information recording medium, each ring-shaped spacer is uniformly fused to the surface of the resin substrate.

In other words, the information recording medium of the present invention has two resin substrates that are evenly and well fused together through the inner and outer spacers, has excellent dimensional accuracy, and has excellent dimensional accuracy. Substantially no peeling occurs, and the recording characteristics of the recording layer are stable over a long period of time. Furthermore, since the above-mentioned information recording medium has excellent dimensional accuracy, there is little axial surface runout during disk reproduction, and the axial acceleration is extremely small.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an example of a method for manufacturing an information recording medium of the present invention. FIGS. 2 and 4 are cross-sectional views of examples of outer ring-shaped spacers used in the information recording medium of the present invention. 3 and 5 are cross-sectional views of examples of the information recording medium of the present invention. FIG. 6 is a diagram for explaining a conventional method of manufacturing an information recording medium. FIGS. 7A and 7B are diagrams showing the relationship between the distance from the outer peripheral edge of a bulge formed at the outer peripheral edge of the resin substrate on the side where the recording layer is provided and the height. 11a, llb, 61a, 61b Two disk-shaped resin substrates 12.62: Inner ring-shaped spacer 13.43.63: Outer ring-shaped spacer 14.64
: Ultrasonic fusion machine 15.65: Ultrasonic application horn 16.66: Jig 17.67: Ultrasonic oscillator 18.68: Converters 19a, 19b, 69a, 69b: Holes 20a, 20b
, 70a, 70b: Inner non-recording area 21a, 21b, 71a, 71b: Outer non-recording area 22a, 22b, 72a, 72b: Recording layer 23a, 23b, 73a, 73b = bulge 24.25.
74.75: Ring-shaped convex portions 26a, 26b, 28a, 2
8b: Inner ring-shaped spacer fused parts 27a, 27b, 29a, 29b: Outer ring-shaped spacer fused parts 30: Notches 72a, 72b: Bulges

Claims (1)

[Claims] 1. Two disk-shaped substrates, at least one of which has a recording layer, are joined with the recording layer inside through an inner ring-shaped spacer and an outer ring-shaped spacer. An information recording medium having an air sandwich structure, wherein the contact position between the outer periphery of the outer ring-shaped spacer and each substrate is 0.1 mm from the outer periphery of the surface of each substrate on the recording layer side.
An information recording medium characterized by being located inside within a range of the above and 1.5 mm.