JPH0798898A - Device and method for initializing optical disk - Google Patents

Abstract

PURPOSE:To prevent an accident caused by the contact with a magnet and also to surely initialize a magnetic layer with high coercive force by providing a supporting member of an optical disk in the neighborhood of an initializing means consisting of the magnet. CONSTITUTION:The initializing means consisting of a permanent magnet or an electromagnet 2 is provided at the position adjacent to both surfaces of the optical disk 1 so as to insert and hold the specified area. The supporting member 3 of optical disk 1 providing the tip part is arranged at the position slightly projected from the position of the tip of initializing means. The tip part of this supporting member 3 is located 0.1-5mm apart from the tip part of the initializing means. Then, the initialization of a recording layer of the disk 1 is executed by arranging this recording layer closely to the initializing means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an initialized optical disk, and more particularly to an optical disk initialization apparatus and manufacturing method.

[0002]

2. Description of the Related Art A magneto-optical recording medium is a high-density recording medium which has recently attracted attention because it can be recorded and reproduced many times by erasing recorded information once. Generally, a magneto-optical recording medium is composed of a transition metal such as iron or cobalt and a rare earth metal such as terbium or dysprosium,
The directions of these magnetizations are perpendicular to the medium surface.
Information is recorded as a mark having a magnetization direction opposite to the surrounding by applying a magnetic field from the outside while locally heating the medium by irradiating a laser beam focused to about 1 μm. .

In order to perform such recording, it is necessary for the medium to have the direction of magnetization aligned in one direction in advance (hereinafter, this step will be referred to as initialization). Initialization is performed by applying an external magnetic field larger than the coercive force of the medium. However, in a magneto-optical recording medium utilizing perpendicular magnetization, a material having a composition that increases the coercive force at room temperature is often used because of the advantage that recorded marks are stable. With such a material, the coercive force at room temperature is several kOe or more. In the above media, it takes several kOe ~ 1 to initialize the media.
It is necessary to apply a large magnetic field of 0 kOe or more.
Such magnetic fields are usually obtained within a narrow gap provided in the magnetic circuit incorporating electromagnets and permanent magnets. Media initialization is accomplished by passing the media through such gaps (between magnetic poles).

[0004]

In order to obtain a large magnetic field, the gap is preferably as narrow as possible and is usually about several mm. On the other hand, the substrate used for the recording medium is generally warped, and in the conventional initialization method of simply passing through the gap, the substrate surface may come into contact with one of the magnetic poles on both sides of the gap, resulting in damage to the substrate surface. there were. Initialization was performed by widening the gap in order to prevent accidents due to contact, but the magnetic field strength decreased, and there was a problem that initialization could not be performed with a recording medium having a large coercive force.

[0005]

As a result of earnest research, the present inventor has improved the initialization device so that even a recording medium having a large coercive force can be surely initialized without damaging the substrate surface. The device and the initialization method were found. Therefore, the present invention is, firstly, "initializing means, which are installed at positions close to both surfaces so as to sandwich a predetermined area of an optical disc, and which are composed of permanent magnets or electromagnets, and are located in the vicinity of the initializing means. An optical disk initialization device (claim 1) comprising a support member for the optical disk having a tip at a position slightly protruding from the position of the tip.

Secondly, "the apparatus according to claim 1 (claim 2), wherein the tip of the support member of the optical disk is located at a position separated by 0.1 to 5 mm from the tip of the initialization means." I will provide a. Thirdly, in the initialization method for initializing the recording layer by bringing the recording layer of the optical disc having the recording layer formed of the magnetic film on the substrate close to the initialization means for initializing the recording layer. An optical disk initialization method characterized in that the optical disk is moved along a support member of the optical disk which is located in the vicinity of the initialization means and has a tip portion slightly protruding from the position of the tip of the initialization means ( Claim 3) "is provided.

Fourth, "In the initialization method of the above-mentioned claim 3, the disk is moved along the tip of the support member at a position 0.1 to 5 mm away from the tip of the initialization means. Optical disk initialization method (claim 4) ".

[0008]

By pressing the surface of the substrate along the support member and passing it between the magnetic poles, it is possible to prevent the substrate surface from being scratched due to contact with the magnetic pole even in a substrate having a large amount of warpage. Since the supporting member is made of a material having a hardness lower than that of the recording medium, the surface of the supporting member is not scratched. Such materials include Delrin,
Examples include plastic and acrylic, but any elastic body can be used.

Further, since it is possible to reduce the distance between the magnetic poles and obtain a large magnetic field strength, it is possible to initialize even a medium having a large coercive force. In this embodiment,
Although the support member having the shape shown in FIG. 1 is installed,
The rod does not have to be rod-shaped as long as the tip is located at a position slightly protruding from the tip of the initialization magnet.

[0010]

EXAMPLE First, a SiN film (7) as an inorganic protective layer of 700 Å and a recording layer of Tb were formed on a circular substrate having a diameter of 30 cm.
FeCo film (8) 100 Å, and S as an inorganic protective layer
The iN film (7) was formed by the 700Å sputtering method. Next, a UV curable resin (10) was formed as an organic protective layer by a spin coating method to prepare a single plate type magneto-optical disk (FIG. 2). The coercive force of this disk measured by using a Kerr rotation angle measuring device was about 10 kOe. 1mm from the magnetic pole on the substrate surface side of the disk created in this way
Initialization was performed by pressing the protruding urethane support member (3) with a force of 10 g and passing it between magnetic poles with a gap of 5 mm. Although the mounting of the disk on the initialization device is performed manually, a moving means for the substrate or the initialization device may be provided in view of the efficiency of the work.

In the present invention, the gap is 0.1 to 5 mm, preferably 2 to 3 mm. The magnetic field between the magnetic poles is about 15
It was kOe. Next, this magneto-optical recording medium was rotated at a linear velocity of 9 m / s by an evaluation device, and the noise level was measured using a spectrum analyzer. The laser power during reproduction was 1.5 mW, and the reproducing magnetic field strength was 0 Oe.
The noise level at this time was -69 to -72 dBm in the frequency range of 1 to 10 MHz. Next, in this medium, 1.
A 5 MHz signal was recorded. The power of the laser beam irradiated during recording was 6 mW, and the strength of the applied magnetic field was 300.
With Oe, the application direction was opposite to the magnetic field direction at initialization.
When the recorded information is reproduced, the carrier level at 1.5 MHz is -15 dBm and the noise level is -71d.
It was Bm. Further, no increase in noise level of 1 dB or more was observed.

Further, while irradiating the recorded mark with laser power of 7 mW, the mark 500 is moved in the same direction as that at the time of initialization.
It was erased while applying a magnetic field of Oe. The noise level after erasing was the same as before recording the mark. This confirmed that the medium was completely initialized by the magnetizing initialization device.

[0013]

As described above, by using the supporting member according to the present invention, accidents due to contact with the magnet can be prevented, and the gap can be made as narrow as possible, so that the initial magnetic layer having a high coercive force can be obtained. The conversion can be surely performed.

[Brief description of drawings]

FIG. 1 is a front view (upper diagram) and a side view (lower diagram) of an initialization device according to the present invention.

FIG. 2 is a sectional view of a single plate type optical disc according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Single plate type optical disk 2 ... Initializing magnet 3 ... Supporting member 6 ... Circular substrate 7 ... Inorganic protective layer 8 ... Recording layer 9 ... Inorganic protective layer 10.・ Organic protective layer

Claims (4)

[Claims] 1. An initialization means comprising permanent magnets or electromagnets, which are installed at positions close to both surfaces so as to sandwich a predetermined area of an optical disk, and are located in the vicinity of the initialization means, and the position of the tip of the initialization means. An optical disk initialization device comprising a support member for the optical disk having a tip portion at a position slightly protruding. 2. The apparatus according to claim 1, wherein the tip of the support member of the optical disk is located at a position separated by 0.1 to 5 mm from the tip of the initialization means. 3. An initialization method for initializing a recording layer by bringing the recording layer of an optical disk having a recording layer formed of a magnetic film on a substrate close to an initialization means for initializing the recording layer. In the method for initializing an optical disc, the optical disc is moved along a support member of the optical disc that is located near the initialization unit and has a tip portion that slightly protrudes from the position of the tip of the initialization unit. . 4. The initialization method according to claim 3, wherein the disk is moved along the tip of the support member located at a position 0.1 to 5 mm away from the tip of the initialization means. Optical disk initialization method.