JPS61194663A - Substrate for photomagnetic disk - Google Patents

Abstract

PURPOSE:To easily manufacture a glass substrate with track guide grooves and to improve secular deterioration characteristics by joining a glass substrate of <=0.5mm in thickness where track guide grooves are formed by a press onto a plane disk made of a transparent inorganic material such as glass and a transparent plastic disk by using a resin adhesive. CONSTITUTION:The glass disk 7 where track guide grooves are formed is placed on a press bench 8 firstly and moved in a conveyance chamber which is heated to about 100 deg.C lower a glass transition point to enter a press chamber heated to about 5-10 deg.C lower than the glass transition point. The glass disk 7 after being pressed is taken out through a conveyance chamber heated to 50-100 deg.C lower the glass transition point. This press-formed glass substance of <=5mm in thickness is joined onto a plastic plane disk of PM-MA, PC, etc., or glass plane disk by using epoxy resin or ultraviolet-ray setting resin.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention records and erases information on a magneto-optical recording medium film such as 'rb'B'eQQ by using a laser beam.
This invention relates to a substrate for a magneto-optical disk that is considered to be used in information recording systems such as video disks and digital audio disks.

[Summary of the invention]

The present invention relates to a magneto-optical disk that can be used as an information recording system, the substrate of which is a flat disk of transparent plastic such as PMMA or PC, or a flat disk of transparent inorganic material such as glass, on which track guide grooves are formed by pressing. Thickness 0.
A magneto-optical disk with excellent environmental resistance is provided by bonding glass disks of less than 5 ms using an adhesive such as an ultraviolet curing resin or an epoxy resin.

[Conventional technology]

Rare earth transition metal magneto-optical materials have been widely used as recording media for magneto-optical disks due to their many advantages in magneto-optical properties, but due to their poor environmental resistance, various efforts have been made. ing.

If PMMA or PC is used as a substrate for a special magneto-optical disk, the characteristics will deteriorate in a few weeks due to the hygroscopicity of these plastic materials. On the other hand, magneto-optical disks using glass substrates show little characteristic deterioration even after being left for one year. However, it is difficult to form track guide grooves on glass substrates, making it difficult to put them to practical use in laser discs and digital audio discs. In order to eliminate the above drawbacks, attempts have been made to bond a plastic substrate with track guide grooves to a glass substrate, or to form track guide grooves with photoresist on a glass substrate, but magneto-optical recording media Since the film was formed on a plastic substrate, it was not possible to form a high-quality film.

[Problem that the invention seeks to solve]

The present invention attempts to solve the problem of deterioration of the characteristics of a magneto-optical disk over time when a plastic substrate is used as described above, and the problem that it is difficult to form track guide grooves on a glass substrate. It is something.

[Means for solving problems]

The present invention is a transparent plastic flat disk such as PMMA or PQ, or a transparent inorganic material disk such as glass, and a glass disk with a thickness of 1.5 ttrx or less on which track guide grooves are formed by pressing, using ultraviolet curing resin or epoxy resin. The above problem was solved by manufacturing a magneto-optical disk substrate with track guide grooves directly on a glass substrate by bonding with an adhesive such as .

〔Example〕

Next, one embodiment of the structure of the magneto-optical disk substrate according to the present invention will be described. FIG. 1 is a block diagram of a magneto-optical disk substrate according to the present invention, in which (1) is a glass flat disk, (2)
) is an epoxy adhesive layer, and (3) is a glass disk with track guide grooves formed by pressing. Glass disk (1) is PM
It may be an MA disk or a PC disk. The thickness of the glass disk with track guide grooves is α5M11g and 8 mm, the track guide groove depth is 600A, the track width is 1.2 μm, and the rack pitch is 2.5 μm. Note that the magneto-optical recording medium is formed on the track guide groove forming surface of the glass disk with track guide grooves.

Next, a method for manufacturing a magneto-optical disk substrate according to the present invention will be described. Figure 2 shows the glass disc f! with track guide grooves in Figure 1! : Schematic diagram showing a press machine for manufacturing, (4) is a press shaft, (5) is a master disk,
(6) is a cooling pipe for cooling the press shaft, (7) is a glass disc used as a raw material, (8) is a press stand, and (9) is a feed shaft for moving the glass disc (7). be. The glass disk (7) can be heated from the outer periphery by a heater. A glass disk (7) for forming track guide grooves is first placed on a press stand (8), and the feed shaft (
9) and enters a press chamber heated to about 5 to 10° C. higher than the glass transition point. In the press room, the glass disk (7) is pressed using a master disk using Ir.

At this time, the press shaft (4) is heated approximately 550 to 60 mm by the cooling water.
It is cooled to 50°C. Also, the press pressure is 120mmφ
When pressing a glass disk, the total load is 60 yang. After pressing, the glass disk (7) is slowly ejected by a feed shaft (9) through a transfer chamber heated to 50 to 100° C. lower than the glass transition point. In addition, master 1a
It is manufactured by the same known method as that used for manufacturing the master disk of n-compact discs, but other metals such as Co, Mo, and W are suitable as the master disk material. Additionally, Ar gas was introduced into the press chamber to prevent oxidation of the master disk.

Next, the inventor discovered that the thickness of the glass disk to be pressed is important in order to prevent the glass disk from being broken or distorted. FIG. 2 is a plot of the disk quality when the outer diameter and thickness of the magneto-optical disk substrate according to the present invention are varied, where O indicates a good quality disk substrate, Δ indicates a distorted disk substrate, An x mark indicates a disk substrate with cracks. Third
The figure shows that it is difficult to manufacture the magneto-optical disk substrate of the present invention unless the thickness is α5 or less.

The glass substrate press-molded as above is PM-MA,
A magneto-optical disk substrate according to the present invention was prepared by bonding it to a plastic flat disk such as a PC or a glass flat disk using an epoxy resin or an ultraviolet curing resin. In addition, when using a plastic disc, pc
It has been found that PM-MA disks have better characteristics when producing magneto-optical disks than disks.

Next, the characteristics of a magneto-optical disk using the magneto-optical disk substrate according to the present invention will be explained.

50 OA of ZnS was deposited on each of the magneto-optical disk substrate, PMMA substrate, and glass substrate according to the present invention.

TbFeC! o to 100OA, further ZnS to 1011
When a magneto-optical disk with 0X formation was prepared and its c/N was examined, it was found that when the magneto-optical disk substrate according to the present invention was used, 07N = 57 dB, when a PMMA substrate was used, 0/N = 54 dB, and when the glass substrate was used, 0/N = 57 dB. By using the magneto-optical disk substrate according to the present invention, it is possible to produce a magneto-optical disk with characteristics equal to or better than those of a magneto-optical disk made with a glass substrate. It turns out that it can be made.

Furthermore, FIG. 5 is a diagram showing the C/N deterioration over time of a magneto-optical disk manufactured using the magneto-optical disk substrate according to the present invention. It turns out that it can be made.

〔Effect of the invention〕

As described above, the magneto-optical disk substrate according to the present invention is a transparent plastic disc such as PMMA or PC, or a flat disc of a transparent inorganic material such as glass. A glass substrate with track guide grooves can be easily produced by bonding disks together using an adhesive such as ultraviolet curing resin or epoxy resin. It makes it possible to easily produce magnetic disks, and has an extremely large effect on the quality and reliability of high-density memories in the field of information processing such as digital audio disks and video disks.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a glass substrate for a magneto-optical disk according to the present invention, and FIG. 2 is a diagram showing a press for producing a glass substrate with track guide grooves using a press among the components of the substrate for a magneto-optical disk according to the present invention. FIG. 3 is a diagram showing the possible manufacturing range of the magneto-optical disk substrate according to the present invention when the disk outer diameter and disk thickness are changed, and FIG. FIG. 2 is a diagram showing deterioration over time of a magneto-optical disk using a disk substrate for a magneto-optical disk. (1)...Glass flat disc (2)...Adhesive layer (3)...Glass disc with track guide groove (4)
...Press shaft (5) ...Master board (6) ...Cooling pipe (7) ...Glass disc (8) ...・Press stand (9)...Feed axis or above Applicant Seiko Electronic Industries Co., Ltd. Agent Patent attorney

Claims (1)

[Claims] A glass disk with a thickness of 0.5 nm or less with track guide grooves formed by pressing on a transparent plastic flat plate such as PMMA or PC or a transparent inorganic flat disk such as glass is bonded with ultraviolet curing resin or epoxy resin. A substrate for a magneto-optical disk, characterized in that the substrate is bonded using an agent.