JPH10340488A - Production of information recording carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate an unbalanced amt. and to obtain stable rotation by applying an adhesive on two transparent substrates in such a manner that the thickness of the adhesive is partially changed to compensate the uneven load of the substrate around the rotation center. SOLUTION: The unbalanced amt. around the rotation center of a substrate 1 and the position 5 where the unbalanced amt. exists are determined. If the unbalanced amt. of the substrate 1 and the load on the position 5 is less than the desired load, an adhesive is applied in the following processes. First, the adhesive 3a is uniformly applied by using a screen printing plate 4a on the area of the substrate 1 to be coated with the adhesive. Then the adhesive 3b of a mass corresponding to the unbalanced amt. of the substrate 1 is applied on the unbalance position 5 by using a screen printing plate 4b. The adhesive is applied by the same method on the other substrate to be laminated, and these substrates are laminated with the adhesive-coated faces inside. Thereby, the unbalanced amt. is eliminated after lamination, and therefore, a simple, small-size, lightweight and low-cost recording and reproducing device can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording carrier such as an optical disk for optically recording and reproducing information, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An optical disk is an information recording carrier having a high density and a high recording capacity, and is used as a memory mainly for a computer, such as image data and document data.

In recent years, there has been a demand for a higher disk rotation speed in order to achieve higher density recording capacity and higher reading speed.

Conventionally, as such an optical disk, a recording film layer is formed on at least one signal surface of two transparent substrates, and an adhesive is applied onto the recording film of the substrate and bonded. There is known a structure having such a structure.

As a prior art of this method of laminating optical disks, there is a method of applying a hot-melt type adhesive with a roll coater and laminating as described in, for example, Japanese Patent Application Laid-Open No. 58-6536. This method is known to be excellent in mass productivity and to obtain an optical disc of excellent quality.

Hereinafter, a conventional information recording carrier and a method for manufacturing the same will be described. 3A to 3C show an example of a conventional optical disk using the above-described prior art and an example of a manufacturing method thereof.

In FIG. 3, after a recording film (2) is formed on a disk-shaped transparent substrate (1) having a center hole (6) by a method such as vacuum evaporation or sputtering, as shown in FIG. Roller conveyor (1
3) 120 ° C. in a heating tank (12) on the recording film (2) while pressing the transparent substrate (1) moving in the direction of the arrow on the coating roll (10) with the press roll (11).
(3) is applied to a thickness of about 30 to 50 μm with a hot-melt adhesive dissolved at about 150 ° C.

Next, hot melt type adhesive 2 was applied.
After laminating the transparent substrates (1) on top of each other so that the adhesive application surfaces are on the inside, as shown in FIG. 3 (C), pressure is applied by upper and lower press plates (14) and (15) of a press machine. And stick them together.

[0009]

However, according to the above-mentioned conventional method, an uneven load (hereinafter, referred to as an unbalance amount) with respect to the center of rotation is caused in the bonded optical disk due to uneven thickness of the transparent substrate and contact with the core. ) Occurs.
Therefore, in the case of an optical disk that rotates at a high speed of 1000 revolutions per minute or more, an excessive moment of inertia is applied to the rotation axis of the recording / reproducing apparatus even if the amount of imbalance is slight, and the recording / reproducing apparatus may generate vibrations, Not only hinders control of the motor, but also in extreme cases damages the rotary drive parts.

For this reason, it is necessary to ensure high rigidity around the rotation axis of the recording / reproducing apparatus, which has led to an increase in manufacturing cost, an increase in size of the equipment, and an increase in weight.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing an information recording carrier which rotates stably by eliminating an imbalance amount of the information recording carrier. Things.

[0012]

In order to achieve the above object, a method for manufacturing an information recording carrier according to the present invention comprises forming a recording film layer on at least one signal surface of two transparent substrates. An information recording carrier in which an adhesive is applied on a recording film of a substrate and bonded to each other, wherein the thickness of the applied adhesive is partially changed to offset a biased load with respect to the rotation center of the substrate. It is assumed that.

Further, as a specific means for applying the adhesive, a general screen printing method or a pad printing method can be used. First, the adhesive is uniformly applied to the entire surface of the substrate, and then, An adhesive having a mass that offsets the partial load can be applied and bonded to a portion having a partial load with respect to the rotation center of the substrate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a recording film layer is formed on at least one signal surface of two transparent substrates, and an adhesive is formed on the recording film of the substrate. A method for manufacturing an information recording carrier by applying and bonding, wherein the thickness of the applied adhesive is partially changed to offset the offset load with respect to the rotation center of the substrate. According to the second aspect of the present invention, first, an adhesive is uniformly applied to the entire surface of the substrate, and then, an adhesive having a mass that offsets the partial load is applied to a portion having an offset load with respect to the rotation center of the substrate. And has the effect of realizing a disk that achieves stable rotation with little dynamic imbalance.

According to a third aspect of the present invention, an adhesive having a large specific gravity is used as an adhesive for offsetting an unbalanced load on the substrate, wherein an adhesive mixed with metal powder is used. 5. The method according to claim 4, wherein the amount of the adhesive for biasing load is small.
The invention described in (1) is characterized by dispersing and applying an adhesive for offsetting the unbalanced load on the substrate, and has an effect of preventing the thickness deformation of the optical disc due to the localized application of the adhesive.

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings. In the following embodiments, the present invention is applied to a method for manufacturing an optical disk, and each embodiment will be described.

In the drawings, portions having the same structure and operation as those of the conventional optical disk manufacturing method are denoted by the same reference numerals.

FIGS. 1A to 1C and FIGS. 2D to 2E.
FIG. 2 is a process diagram for sequentially explaining an optical disc bonding process showing an embodiment of the present invention.

First, as shown in FIG.
And a substrate 1 formed by vacuum deposition, sputtering, etc.
Are manufactured in the same manner as in the conventional example.

Next, the amount of imbalance with respect to the center of rotation of the substrate 1 and its position 5 are determined by an offset load measuring device (for example, an Akashi vertical balance tester manufactured by Akashi Seisakusho, etc.).

In this embodiment, the unbalance amount of the substrate 1 and its position 5 indicate a portion where the load is insufficient. Further, the position 5 of the unbalance amount is the position of the substrate 1
Represents the angle with respect to the reference position. It is obvious that the reference position may be a mark transferred at the time of molding the substrate or a mark added at the time of measurement.

Next, as shown in FIG. 1 (B), using a screen printing plate 4a having a mesh-like hole in a region where the adhesive is to be applied, the adhesive 3a is applied by a generally known screen printing method. Apply evenly on substrate 1.

Next, as shown in FIG. 1 (C), a screen printing plate 4 provided with a mesh-shaped hole for applying a required amount of adhesive 3b having a mass corresponding to the unbalance amount 5 of the substrate.
FIG. 1B, the portion of the substrate 1 at the unbalanced position 5 is
It is applied in the same manner as in (B). Thereby, the unbalance amount 5 of the substrate is offset.

Next, an adhesive is applied to the other substrate to be bonded in the same manner as in FIGS. 1A to 1C, and as shown in FIG. 1D, the surface to which the adhesive is applied is applied. Are placed inside each other, and they are bonded together by pressing as shown in FIG.

In this way, the unbalanced amount of the substrate is completely eliminated, and the optical disk is bonded as shown in FIG.
Since there is no amount of imbalance with respect to the center of rotation, even if the optical disk is rotated at a high speed, an excessive moment of inertia is applied to the rotating shaft of the recording / reproducing apparatus, thereby preventing rotation unevenness and vibration.

As the substrate 1 used in the present invention, an acrylic resin, a polycarbonate resin, glass, or the like, which has been generally used conventionally and has excellent light transmittance, can be used. As the adhesives 3a and 3b, generally used urethane-based, epoxy-based, and acrylic-based adhesives are used.
A silicone-based adhesive can be used, and a liquid thermosetting reaction or ultraviolet curing reaction type adhesive is preferable.

Further, the adhesive is applied with a thickness of several tens of μm. In order to offset the imbalance amount of the substrate with a small amount of the adhesive, a metal powder is mixed into the adhesive. It is preferable to use an adhesive having a large specific gravity. In this case, fine metal powder having a specific gravity as large as possible and stable against oxidation is preferable, and examples thereof include lead, tin, iron, and the like that have already been oxidized or nitrided before mixing.

If the adhesive is applied thickly at one location, the optical disc may be deformed due to uneven thickness. Therefore, it is preferable to apply the adhesive in a wide range in the vicinity of the target angle for uneven loading. Since the amount of unbalance is a moment force, it is desirable that the thickness of the outer periphery be increased.

In this embodiment, first, an adhesive is uniformly applied to the entire surface of the substrate 1, and then, an adhesive having a mass that offsets the imbalance is applied to a portion having an unbalance amount with respect to the rotation center of the substrate 1. The adhesive has been applied and the adhesive has been applied twice, but the order may be reversed, and a different type of adhesive may be used. For example, first, the substrate 1
After applying and curing the adhesive 3b that offsets the unbalanced amount of the adhesive, the adhesive 3a may be applied to the entire surface and the two substrates may be bonded to each other. In this case, a hot melt adhesive is used. can do.

The thickness of the adhesive to be applied is partially changed by a method such as changing the thickness of the plate or the size of the mesh in the portion of the screen plate 4a corresponding to the screen printing plate 4b. It can also offset the imbalance.

Further, in the present embodiment, a screen plate and a method using a screen printing method have been described as a specific method of applying the adhesive, but the same applies even when a generally known pad printing method is used. The effect of can be obtained. In this case, as in the case of the screen plate, the adhesive for offsetting the unbalance amount may be applied in one operation by partially changing the thickness of the pad printing plate.

If an unbalanced load is too large for the adhesive to absorb the unbalanced load, the unbalanced load is measured, the unbalanced load is classified into a certain amount, and the materials to be bonded are unbalanced. The above effects can be obtained with a relatively small amount of adhesive by laminating in a direction in which is offset and adding an adhesive corresponding to the difference in the partial load.

Further, the accuracy can be further improved by re-measuring with the biased load measuring device in the above-mentioned bonding step after the application of the adhesive.

[0034]

As described above, according to the present invention, since the unbalance amount of the substrates is offset by the adhesive before the bonding, the unbalance amount of the information recording carrier after the bonding is eliminated, and the quality is greatly improved. Can be improved.

For this reason, an excessive inertia moment is given to the rotating shaft of the recording / reproducing apparatus by the unbalance amount of the information recording medium rotating at a high speed, and there is no occurrence of rotational unevenness or vibration. Can be simplified, and can be reduced in size and weight, and the cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a process diagram of an optical disk and a method of manufacturing the same according to the present invention.

FIG. 2 is a process diagram of an optical disk and a method of manufacturing the same according to the present invention.

FIG. 3 is a process diagram of a conventional optical disc manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording film 3a, 3b Adhesive 4a, 4b Screen plate 5 Unbalance position of substrate 6 Center hole

Claims (4)

[Claims] An information recording carrier is formed by forming a recording film layer on at least one signal surface of two transparent substrates and applying and bonding an adhesive on the recording film of the substrate. A method of manufacturing an information recording carrier, wherein a thickness of the applied adhesive is partially changed so as to cancel an offset load with respect to a rotation center of the substrate. 2. A recording film layer is formed on at least one signal surface of two transparent substrates, and an adhesive is applied on the recording film of the substrate and bonded to form an information recording carrier. In a manufacturing method, first, an adhesive is uniformly applied to the entire surface of the substrate, and then, the adhesive having a mass that offsets the partial load is applied to a portion having a partial load with respect to the rotation center of the substrate. A method for producing an information recording carrier, characterized in that the carrier is bonded together. 3. An adhesive for offsetting an unbalanced load on a substrate,
3. The method for producing an information recording carrier according to claim 1, wherein an adhesive mixed with a metal powder is used. 4. The method for manufacturing an information recording carrier according to claim 1, wherein an adhesive for offsetting an uneven load on the substrate is dispersed and applied.