JPH01133236A - Production of information recording medium - Google Patents

Abstract

PURPOSE:To obtain a center hole in a laminated recording medium with good accuracy by subjecting the center hole to finishing while positioning the center of the laminated information recording medium by using a cutting tool having a guide which is the same in shape as the section of a center shaft. CONSTITUTION:One of two sheets of the information recording film substrates 5a, 5b which are previously centered is set to a sticking jig 6 by bringing the side where the information recording film 2a exists on the upper side in such a manner that the center hole 4 and the center shaft 7 are aligned. After an adhesive agent is coated atop this substrate 5a, another substrate 5b is set by facing the information recording film 2b downward in such a manner that the center hole 4 and the center shaft 7 are aligned as well, then both the substrates are adhered by pressurizing the same from above until the thickness of the adhesive agent is uniformized. The excess adhesive agents bleeds out and accumulates mainly in the recesses 9 of the center shaft. After this adhesive agent is cured, the laminated information recording medium is removed from the jig 6. The centering is executed and the finishing of the center hole is executed by means of the cutting tool having the guide which is the same in shape as the section of the shaft 7 in the cutting stage.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing an information recording medium, and more particularly, to an information recording medium used for a video disc, an information file, etc. Concerning a method for producing a medium.

(Prior Art) In recent years, high-density, large-capacity information recording media for use in video discs, information files, etc. have been developed.

Plastics such as polycarbonate and PMMA are used as substrate materials for this type of information recording medium because of their ease of manufacture. The basic structure of an information recording medium is that an information recording film is formed on one side of a substrate made of such a material.
Additionally, in order to increase capacity, many have a bonded structure. In this specification, a substrate having a structure in which an information recording film is formed on one side of the substrate is referred to as "f information recording film substrate".
That's what it means.

FIG. 5 shows a structural cross-sectional view of an example of a bonded information recording medium. In FIG. 5, la and lb are substrates, 2a,
2b is a material (e.g. Te, TeOx
), 3 is an adhesive layer, 4 is a center hole, and 5a and 5b are information recording film substrates. This information recording medium has a structure in which information recording film substrates 5a and 5b are bonded together, and a minute spot of laser light whose intensity is modulated by an information signal is projected through the substrate 1a or 1b. A signal is recorded by causing the information recording film 2a or 2b to undergo a phase change according to the information signal by heat, and the information signal recorded on the information recording film 2a or 2b is transferred to the information recording film 2a or 2b at a certain level. It is used in an optical recording and reproducing method in which a spot of high-intensity laser light is applied and the reflected light is reproduced by photoelectric conversion.

The information recording medium shown in FIG. 5 includes two information recording film substrates 5.
After applying an adhesive to the surface of one of the information recording film substrates 5a on which the information recording film 2a exists, the information recording film 2b of the other substrate 5b is applied to the information recording film a and 5b with the adhesive layer 3 in between. It is manufactured by bonding the parts 2a and 2a facing each other. In manufacturing, the center hole 4 must not only have dimensional accuracy but also sufficient positional accuracy. That is, in order to guarantee tracking performance, it is necessary to suppress the eccentricity of the center hole 4 with respect to the concentric or spiral information track to about 50 LLm or less for the information recording medium alone.

(Problems to be Solved by the Invention) However, in this conventional manufacturing method, the center hole 4
It was difficult to ensure positional accuracy.

That is, when the adhesive is applied and pressed, the adhesive overflows from the outer peripheral end face and the end face on the side of the center hole, particularly making the center hole smaller, or even adheres to the surface of the substrate. Even if the amount of adhesive, application position, pressure bonding method, etc. are adjusted, the shape and size of the overflowing adhesive will not be the same every time.

For this reason, before obtaining a finished product, the information recording medium after lamination must be centered by detecting the information track, removing the overflowing adhesive, and adjusting the center hole 4 to a predetermined size. Complicated processing such as finishing within precision is required, making manufacturing difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily manufacturing an information recording medium that satisfies the accuracy requirements by eliminating the drawbacks of such conventional manufacturing methods.

(Means for Solving the Problems) The present invention provides a method for manufacturing a bonded information recording medium, in which a pre-centered information recording film substrate is formed into a recess along the axial direction on the circumferential surface of a center shaft. After fitting and bonding into the provided bonding jig, a cutting tool having a guide having the same cross-sectional shape as the center axis is used to position the center of the bonded information recording medium and cut a center hole. This is a method for manufacturing an information recording medium, which is characterized by performing finishing processing.

(Function) Since the bonding jig according to the present invention is provided with a concave portion along the axial direction on the circumferential surface of its center shaft, adhesive overflows around the center hole when bonding information recording film substrates. can escape into this recess, and can prevent the adhesive from adhering to the surfaces of the substrates 1a and lb.

Furthermore, since the cutting tool according to the present invention has a guide having the same cross-sectional shape as the center shaft at its tip, if this guide is fitted into the center hole after being extracted from the center shaft, it is possible to The positional relationship between the center axis and the center hole can be exactly reproduced, and if the center hole is cut according to this guide, sufficient positional accuracy of the center hole can be ensured.

(Example of the invention) Hereinafter, the present invention will be explained with reference to drawings showing embodiments.

The method for manufacturing an information recording medium of the present invention includes a bonding process in which information recording film substrates that have been centered in advance are laminated, and a cutting process in which finishing operations such as positioning of a center hole are performed.

In the bonding step, for example, two information recording film substrates, which have been centered in advance, are fitted into a bonding jig provided with a concave portion along the axial direction on the circumferential surface of the center shaft, and the substrates are bonded together.

FIG. 1 shows a cross-sectional view of an example of a bonding jig used in the bonding process, and the figure also shows the state in which the information recording medium after bonding is housed in the jig. In this figure, 6 indicates a bonding jig, 7 indicates a center axis of the bonding jig, and 8 indicates a pedestal. As shown in this figure, the bonding jig 6 consists of a circular pedestal 8 made of a flat plate having approximately the same diameter as the substrates 1a, lb, and a center shaft 7 that fits into the center hole 4. Moreover, FIG. 2 shows an AA end view of the center shaft 6. As shown in FIG. 2, the center shaft 7 is provided with a recess 9 extending in the axial direction in the drawing, that is, an adhesive relief part. Figure 2 shows a case where reliefs are provided at four locations around the circumference. In addition, the maximum diameter of the center shaft!
! , 1 are sized to fit perfectly into the center hole 4.

The bonding process is performed, for example, as follows.

two information recording film substrates 5a that have been centered in advance;
5b is set in the bonding jig 6 so that the center hole 4 and the center shaft 7 are aligned with each other, with the side where the information recording film 2a is located facing up. Next, after applying adhesive to the upper surface of this information recording film substrate 5a, set the other information recording film substrate 5b with the information recording film 2b facing downward, also aligning the center hole 4 and the center shaft 7, and then Pressure bonding is performed so that the adhesive layer 3 has a uniform thickness. At this time,
Excess adhesive overflows and mainly enters the recess 9 of the center shaft.
It accumulates in After the adhesive is cured, the pasted information recording medium is removed from the pasting jig 6.

In the cutting process, a cutting tool having a guide having the same cross-sectional shape as the center shaft 7 is used to finish the center hole while locating the center of the information recording medium bonded as described above. . FIG. 3 shows a plan view of the information recording medium after bonding, and in the figure, 10 indicates the center hole after bonding. In this way, the center hole 10 after bonding has approximately the same shape as the cross section of the center shaft 7 due to the solidification of the adhesive that has protruded into the recess 9 of the center shaft. In addition, Fig. 4 is a front view of the cutting tool (a
) and a BB sectional view (b) of the guide portion thereof. In this figure, 11 is a center guide, 12 is a cutting tool,
13 indicates a recessed portion of the center guide. As shown in FIG. 4, at the tip of the cutting tool 12 according to the present invention, a center guide 1 whose cross-sectional shape is the same as that of the center shaft 7 is provided.
1 is attached. Of course, the maximum diameter β of the center guide 11
2 is the same as the center shaft 7, the depth of the recess 13 may be deeper than the recess 9 of the center shaft 7 as long as the effects of the present invention are not impaired.

The cutting process is performed, for example, as follows. Align the center of the center guide 11, which has the same cross-sectional shape as the center shaft 7 and has a tapered tip, in the center hole 10 after bonding by aligning it with the concave part 13 where the adhesive protrudes. The cutting tool 12 is inserted at a slow speed (for example, about 30 cm/min) while maintaining . By further inserting and cutting the cutting tool 12 while rotating it at about 200 to 300 rpm, the desired hole diameter and center positioning is completed.

In addition, in the above, the method of the present invention was explained using an information recording medium formed by bonding two information recording film substrates together.
A device in which one side is replaced with a protective substrate can also be manufactured in the same manner.

(Effects of the Invention) Since the method for manufacturing an information recording medium of the present invention has the above-described configuration, according to the present invention, when manufacturing a bonded information recording medium, It is advantageous in that a high-quality center hole with less eccentricity can be obtained. ■No special centering device is required, and a high-quality one can be obtained easily. ■ The time required for production can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of a bonding jig according to the present invention;
Fig. 2 is an A-A end view of the center shaft, Fig. 3 is a plan view of the information recording medium after lamination, Fig. 4 is a front view of the cutting tool, and Fig. 5 is an example of the laminated information recording medium. FIG. la, lb...substrate, 2a, 2b...information recording film,
3... Adhesive layer, 4... Center hole, 5a, 5b...
・Information recording film substrate, 6... Bonding jig, 7...
Center axis, 9, 13... recess, 10... center hole after bonding, 11... center guide, 12...
··Cutting tools. Figure 1 5b 6 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a method for manufacturing a bonded information recording medium, a bonding jig is provided in which information recording film substrates that have been centered in advance are provided with a recessed portion along the axial direction on the circumferential surface of a center shaft. After fitting and bonding, finish the center hole while positioning the center of the bonded information recording medium using a cutting tool having a guide whose cross section is the same as the center axis. A method for manufacturing an information recording medium characterized by: 2. The information set forth in claim 1, wherein the bonded information recording medium is formed by bonding two information recording film substrates, or by bonding an information recording film substrate and a protective substrate. Method of manufacturing recording media.