JPH04271019A - Initializing device for phase change type optical disk - Google Patents

Abstract

PURPOSE:To execute the ideal initialization of an optical disk. CONSTITUTION:This initializing device for a phase change type optical disk is constituted of at least a laser light source, a condenser lens 11, an optical disk rotary mechanism, and a condenser lens feed mechanism. In the device of such a constitution, an angle theta formed between an optical axis 11A of the lens 11 and the circumferential direction of an optical disk at an intersecting point is not set rectangular with the point 1A formed between the axis 11A and the internal recording film of the optical disk defined as an apex. Thus the laser light condensed on the recording film forms an ellipse having its longer side in the circumferential direction of the optical disk. Then the recording film has a slow temperature change with irradiation of the laser light. Therefore the recording film can be heated up and cooled down. As a result, the ideal initialization for the phase change type optical disk is enabled.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an apparatus for initializing an optical disc for recording, reproducing, and erasing information using a laser beam;
In particular, it is equipped with a laser beam irradiation means consisting of at least a laser light source and a condensing lens, an optical disk rotation mechanism, and a condensing lens feeding mechanism, so that the laser beam emitted from the laser light source is condensed by the condensing lens, and the optical disk rotation mechanism The present invention relates to an initializing device for a phase change optical disc that can record or erase information by changing the optical properties of the irradiation section by irradiating the recording film of the rotating phase change optical disc.

0002

2. Description of the Related Art Optical disk recording and reproducing systems using laser light are capable of storing and reproducing large amounts of data and provide high-speed non-contact access, and are beginning to be put to practical use as large-capacity memories. Optical discs are classified into read-only types known as compact discs and laser discs, write-once types that can be recorded by the user, and rewritable types that can be repeatedly recorded by the user. The rewritable type can be used as an external memory for computers as an alternative to magnetic disks, or as a document/document storage device.
It is expected that it will be used as an image file.

[0003] Rewritable optical disks include phase-change optical disks that utilize phase changes in a recording film and magneto-optical disks that utilize changes in the magnetization direction of a perpendicularly magnetized film. When using a rewritable optical disc, it must be initialized first. In the case of a phase change optical disc, the recording film on the entire surface of the disc must be aligned in a crystalline state. For example, a conventional method for initializing a phase-change optical disk uses an optical head for recording, reproducing, and erasing. As shown in FIG. 5, a laser beam focused into a circular shape of about 1.5 μm is emitted from an optical head 3 for recording, reproducing, and erasing to grooves 2 with a pitch of about 1.6 μm carved on the substrate of the optical disc 1. 4, and by increasing the output of the laser beam, the temperature of the recording film was raised to bring it into a crystalline state.

0004

In phase-change optical recording, two states of the recording film are used for recording and erasing: an amorphous (recorded state) and a crystalline (erased state) state. It is known that an amorphous phase is achieved by rapid heating and cooling, and a crystalline phase is achieved by heating and slow cooling. The initialized state means that the entire surface of the disk is in an erased state, and for this purpose, it is desirable to heat and slowly cool the recording film over the entire surface of the disk. However, if the beam diameter of the laser beam is about 1.5 μm, the temperature of the recording film changes rapidly during initialization, making slow heating and cooling impossible, making it impossible to perform optimal initialization.

An object of the present invention is to provide an initialization device that solves these problems.

[0006]

[Means for Solving the Problems] The present invention aims to irradiate a recording film of a phase-change optical disc that is being rotated by an optical disc rotation mechanism with a laser beam focused by a condensing lens. In an initializing device for a phase-change optical disk capable of recording or erasing information by changing optical properties, the intersection of the optical axis of the condenser lens and a recording film inside the optical disk is the apex, and the condenser lens The condenser lens is arranged so that the angle between the optical axis of the optical disk and the circumferential direction of the optical disk at the apex is not a right angle.

[0007]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an optical disc initialization device according to the present invention. This optical disk initialization device includes a laser light source 5, a mirror 10, a condenser lens 11, an optical disk rotation mechanism 6, and a condenser lens and mirror feeding mechanism 7.

Laser light sources include semiconductor lasers and gas lasers, but their energy density is approximately 1 mW/μm2.
Any laser light source can be used as long as it is above.

The present invention is characterized by the arrangement of the condenser lens 11. That is, the positional relationship between the disk 1 and the condensing lens 11 is as shown in FIG.
The focal length is the distance from the recording film 8 to the condenser lens 1.
With the intersection 1A of the optical axis 11A of 1 and the recording film 8 as the apex,
The condenser lens 11 was installed so that the angle θ between the optical axis 11A and the circumferential direction of the optical disk 1 at the intersection 1A was not a right angle. In this embodiment, the angle θ is set to 45°, but it can be set to an optimal angle depending on the characteristics of the recording film 8 and the rotation speed of the disk. By irradiating the laser beam obliquely with respect to the circumferential direction of the optical disk in this manner, the laser beam 9 forms an elliptical shape on the recording film 8 of the optical disk 1, as shown in FIG.

FIG. 4 shows the temperature change of the recording film 8 of the rotating optical disc 1 when the recording film 8 is irradiated with a laser beam. Curve 12 shows the temperature change in the case of a normal circular laser beam, and curve 13 shows the temperature change in the case of the elliptical laser beam of the present invention.

When a laser beam is irradiated onto any part of the recording film 8 of the rotating optical disk 1, a rapid temperature change is observed with the ordinary circular laser beam, but with the elliptical laser beam of the present invention, the temperature changes. The change was gradual, and slow heating and cooling of the recording film 8 was confirmed.

[0013] As a result of initializing a phase change type optical disc using the initializing device of this embodiment, satisfactory initialization could be performed. In Figure 2, the angle θ is an acute angle,
The same effect can be obtained even if the angle θ is an obtuse angle.

[0014]

As explained above, the intersection between the optical axis of the condenser lens and the recording film inside the optical disk is taken as the apex, and the angle between the optical axis of the condenser lens and the circumferential direction of the optical disk at the apex is made a right angle. By installing a condenser lens to prevent this from happening, it is possible to provide an optical disc initialization device that can initialize an optical disc with higher quality than conventional systems.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of an optical disc initialization device according to the present invention.

FIG. 2 is a diagram showing the positional relationship between a disk and a condensing lens.

FIG. 3 is a diagram showing the shape of laser light on a recording film.

FIG. 4 is a diagram showing the temperature change of the recording film when the recording film 8 of the rotating optical disc 1 is irradiated with laser light.

FIG. 5 is a diagram for explaining a conventional initialization method for a phase change optical disc. 1 Optical disk 2 Groove 5 Laser light source 6 Optical disk rotation mechanism 8 Recording film 9 Laser beam 10 Mirror 11 Condenser lens

Claims (1)

[Claims] [Claim 1] By irradiating a recording film of a phase-change optical disk that is being rotated by an optical disk rotation mechanism with a laser beam focused by a condensing lens, the optical properties of the irradiated part are changed and information is transmitted. In an initializing device for a phase-change optical disc capable of recording or erasing data, the intersection of the optical axis of the condensing lens and the recording film inside the optical disc is the apex, and the optical axis of the condensing lens and the intersection point at the apex are An initialization device for a phase-change optical disk, characterized in that the condenser lens is installed so that the angle between the condenser lens and the circumferential direction of the optical disk is not a right angle.