JPS63136372A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To suppress the increase in double refraction at a change in temperature/humidity as the environmental condition by providing a center metallic fixture comprising ring parts arranged at an interval and parts connecting alternately the inner circumference and the outer circumference of the said parts. CONSTITUTION:The center metallic fixture 2 comprising parts where 12 sectors are arranged as a ring at an interval while short sides are directed inward and parts connecting the inner and outer circumferential parts of the sectors by means of a circular-arc, and an intermediate ring 4 having a projection 5 whose inner and outer diameter is the same as that of the center metallic fixture to be fitted to the center hole of the disk base so as to be fitted easily to the disk substrate 1 because the material is made of a PC resin, are adhered by an epoxy group adhesives and the intermediate ring 4 is adhered to the outside of the inner circumference of the disk base 1 by means of an epoxy resin adhesives. Since the center metallic fixture is deformed comparatively freely in the radial direction, the restriction of the dimensional change due to the temperature/humidity change of the disk substrate is reduced and since the distortion of the disk base is small, the increase in the double refraction is decreased.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to the structure of an optical information recording medium.

(Conventional technology) In recent years, the amount of information stored and handled in offices and homes has tended to increase dramatically. , an information recording medium and an information recording/reproducing apparatus that can reproduce the information are desired.

Conventionally, contact magnetic recording systems have been mainly used to record and reproduce information, but recently optical disk devices that record and reproduce information in a non-contact manner using laser light have been developed and are being put into practical use.

Up to now, two methods have been proposed for clamping optical discs in information recording and reproducing devices: a mechanical chuck method and a magnetic clamp method, but the magnetic clamp method is advantageous for the following reasons.

That is, the structure of an optical disk is roughly divided into three types: a single-plate structure, an air-sand inch structure, and a full-surface contact structure, and the thickness of the information recording carrier differs depending on each structure. Those with a single-disc structure are used for playback-only CDs and CD-ROMES, and the thickness is standardized, so there is no problem, but optical discs on which users can record information can be either single-sided or double-sided recording systems. However, the structure differs depending on the information recording format, that is, a case with a physical shape change such as openings or void formation, and a case without a physical shape change such as magneto-optical or phase change. The former has an air sandwich structure, and the latter mainly has a full-surface contact structure, so the thickness is not uniform.

For this reason, the mechanical method has the drawback that it is not compatible with the mounting and removal of the optical disc in a recording/reproducing device (2), whereas the magnetic clamp method does not have such drawbacks.

By the way, in the magnetic clamp method, it is necessary to fix center fittings for attaching the optical disc to an information recording/reproducing device (two) to both sides of the disc substrate.

The basic structure of a conventional optical information recording medium using the magnetic clamp method is as shown in FIGS. 3a and 3b, and is made of plastic and advantageously uses a recording material 7 for recording information on one or both sides. It is composed of a portion where the disk substrate 1 is bonded with a bonding layer 3 and a flat ring-shaped center metal fitting 6 which is attached to the inner circumference of the disk substrate 1 with adhesive.

(Problems to be Solved by the Invention) However, in this structure, the center metal fitting 6 is ring-shaped and continuously restrains the inner circumferential portion of the disk substrate 1 over 3600 mm. Because radial deformation is not easy (=, change in environmental temperature and humidity 1:
At this time, due to the difference in the materials of the center metal fitting 6 and the disc substrate 1 (
= Therefore, distortion occurs, and when the material of the disk substrate 1 is a material with a large photoelastic constant C (C=O, ♂X / 0"" 6L/dyne), such as polycarbonate (hereinafter abbreviated as PC), The birefringence further increases, resulting in C/N (carrier/
In particular, magneto-optical disks that utilize the magnetic Kerr effect are subject to adverse effects such as a decrease in the noise (noise) ratio, and this is a problem in that the degree of influence is large.

It is an object of the present invention to provide an information recording medium that solves this problem, suppresses the increase in birefringence when the temperature and humidity of the environment changes, and has excellent reliability in terms of recording characteristics.

(Means for Solving the Problems) The structure of the present invention includes portions lined up in a ring shape at intervals, and portions that alternately connect the inner circumferential portions and outer circumferential portions of these portions. The center fitting is fitted onto the inner periphery of the disk substrate.

The inner periphery and the outer periphery of the ring-shaped parts are arranged alternately (the two are connected at the ends (the closer the two are, the better).

The center metal fitting may be attached directly to the inner circumference of the disk substrate with adhesive, or it may be attached to the inner circumference of the disk substrate through an intermediate ring that acts as a buffer layer to reduce the strain applied to the disk substrate. It is also possible.

If the intermediate ring is attached to the inner circumference of the disk substrate, the disk substrate and the intermediate ring should be bonded together using an adhesive (with adhesive, ultrasonic waves, high frequency waves, etc.). Examples include those that are directly melted snow.In addition, the connection between the center metal fitting and the intermediate ring is
Adhesives (for example, those that are made with two or the center metal fitting and the intermediate ring made at the same time by insert molding). It is necessary to provide a burr.

The material of the center metal fitting is corrosion resistant (ferritic or martensitic stainless steel, which is also magnetic), such as JIS standard SUS 4t03.8U.
84t/6.8U84t3θ, Ni, etc. are suitable.

Examples of adhesives include reactive adhesives such as resorcinol, cyanoacrylate, epoxy, and phrethane, and WV.
A. Synthetic rubber, polyester, polyamide-based hot melt adhesives and general purpose resins such as polyethylene, polypropylene, polycarpoite, polymethyl methacrylate, polyester, and polyamide can be used.

To bond using hot-melt adhesives and general-purpose resins, you can use them in a heated, molten state, or apply ultrasonic waves or high-frequency waves as a heat source to melt the resin that has been filled in advance. Compared to methods using reactive adhesives, bonding and curing can be completed in a shorter time, which is extremely advantageous in terms of process.

A suitable material for the intermediate ring is a polymeric material having a coefficient of linear hygroscopic expansion and linear expansion comparable to that of the disk substrate, or a polymeric material having an elastic constant equal to or less than the value of the material of the disk substrate.

(Example) Example: As shown in Figure 73 and ILB, 72 flat sector shapes are lined up in a ring shape with the short sides of the arcs spaced inwards, and these sector shapes. 5USl1 consisting of parts that alternately connect the inner circumferences and the outer circumferences with circular arcs.
03! E! The center metal fitting has the same inner diameter and outer diameter as the center metal fitting; it is made of 4 PCL resin and has one hole in the center of the disk substrate 1 (=fitting It is composed of a ring-shaped intermediate ring 4 having a protrusion 5 and a disk substrate 1 having a recording sensitive material 7 for recording information on one side or both sides (two sides made of PC) bonded together with an adhesive layer 3. The center metal fitting 2 and the intermediate ring 4 are bonded together using an epoxy adhesive, and the intermediate ring 4 is bonded to the outside of the inner peripheral portion of the disk substrate 1 using an epoxy adhesive.

Example 2 As shown in Figs. The inner circumferential parts and the outer circumferential parts are alternate (5U consisting of the parts connected by two circular arcs)
The center metal fitting 2 is made of S1103 and is made of PC on one or both sides (=a portion in which a disk substrate 1 having a recording sensitive material 7 for recording information is bonded together with an adhesive layer 3). is directly bonded to the outside of the inner periphery of the disk substrate 1 with adhesive.

(Effects of the Invention) According to the present invention (2), since the center metal fitting has a shape that can be relatively freely deformed in the radial direction, the disk substrate is more resistant to dimensional changes due to changes in temperature and humidity than conventional optical information recording media. It becomes possible to considerably reduce constraints,
When the environmental temperature and humidity change (2), the increase in birefringence decreased due to the small strain of the disk substrate.

[Brief explanation of the drawing]

FIG. 73 is a plan view of an embodiment of the present invention, and FIG. 7b is a $l
Fig. 2a is a plan view of another embodiment; Fig. 2b is a sectional view taken along line B-B in Fig. 23;
The figure is a plan view of a conventional optical information recording medium, and FIG. 3b is a sectional view taken along line CC in FIG. 3a. 1: Disc substrate, 2: Center metal fitting, 3: Adhesive layer,
4: Intermediate ring, 5: Protrusion, 6: Center metal fitting, 7: Recording sensitive material patent applicant Asahi Kasei Kogyo Co., Ltd. Figure C-C

Claims (1)

[Claims] In an optical information recording medium that is magnetically clamped to an optical information recording/reproducing device, the parts that are lined up in a ring shape at intervals and the parts that alternately connect the inner and outer peripheries of these parts. An optical information recording medium characterized in that a center metal fitting consisting of