JPH0528497A - Optical disk recording, reproducing and erasing method - Google Patents

Abstract

PURPOSE:To provide an optical disk recording, reproducing and erasing method realizing a high data transferring speed. CONSTITUTION:By irradiating a laser beam deflected and scanned to a fixed angular direction to the rotational direction of the optical disk, recording. reproducing and erasing are performed. On the optical disk 10, the tracking guide groove 11 of the laser beam and an information recording flat part 12 adjacent to this guide groove 11 are provided, the optical disk forming the flat part and the guide groove to a concentric circular shape or a spiral shape is used. On an optical head recording, reproducing and erasing, at least two laser light sources, a light deflection element, a condenser lens, a reproducing signal detecting optical system, and a focus and tracking error signal detecting optical system are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing / erasing method for recording / reproducing / erasing information by using a laser beam.

[0002]

2. Description of the Related Art An optical disk recording system using laser light is capable of large-capacity recording and can be accessed at high speed in a non-contact manner.
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. Write-once and rewritable optical discs have begun to be used as external memory of computers or as document / image files.

In the currently used optical disk device,
A reproduction signal is detected from the laser light that is modulated and reflected by the optical disc. For example, in the read-only type, a reproduced signal is taken out by utilizing a change in the amount of reflected light from the pits of irregularities formed on the disc. In the write-once type, a minute pit formed by laser irradiation or a change in reflected light amount due to a phase change is used for reproduction. In a rewritable magneto-optical disk, the magnetization state of the recording film is read out as a change in the deflection surface by utilizing the magneto-optical effect of the recording film. As with the write-once type, the other rewritable type, the phase change optical disk, uses the change in the amount of reflected light due to the phase change for reproduction.

Generally, a file device including an optical disk is required to have a large capacity and a high data transfer speed. To achieve a high data transfer rate on an optical disc, (1) rotate the disc at high speed, (2)
Methods such as using a multi-beam optical head having four or more condensed laser beams, (3) using a multi-head drive equipped with two to four plural heads, and the like have been proposed.

[0005]

However, each of the above-mentioned methods aiming at a high data transfer rate has drawbacks. In other words, for high-speed rotation of the disk, a disk with high rigidity is required, so the disk itself is expensive, and a high-performance servo circuit is required so that the focused laser light can follow the eccentricity and surface wobbling of the disk. There is a drawback that Further, both the multi-beam head and the multi-head drive have a drawback that the device configuration becomes complicated and the device becomes expensive.

An object of the present invention is to solve the above-mentioned drawbacks, and to use an optical head having a simple structure in which only one recording / reproducing / erasing laser beam and one servo laser beam are used, and a high rigidity is required for an optical disk. It is an object of the present invention to provide an optical disc recording / reproducing / erasing method that realizes a high data transfer rate.

Another object of the present invention is to provide an optical disk used for implementing the optical disk recording / reproducing / erasing method of the present invention.

Another object of the present invention is to provide an optical head used for carrying out the optical disk recording / reproducing / erasing method of the present invention.

Another object of the present invention is to provide an optical disk device used for implementing the optical disk recording / reproducing / erasing method of the present invention.

[0010]

The present invention is an optical disk recording / reproducing / erasing method characterized by irradiating an optical disk with laser light which is scanned while being deflected in a certain angle direction with respect to the rotation direction of the optical disk. An optical disk having a guide groove for tracking a laser beam and an information recording flat portion adjacent to the guide groove, the width of the flat portion is wider than the guide groove width, and the flat portion and the guide groove are concentric circles. An optical head for recording / reproducing and erasing is formed by using an optical disc having a circular or spiral shape, and at least two laser light sources, an optical deflecting element, and a condenser lens,
It has a reproduction signal detection optical system and a focus and tracking error signal detection optical system.The laser light from the one laser light source enters the optical deflector and then enters the condenser lens and is reflected from the optical disc. An optical head for an optical disc, which is guided to the reproduction signal detection optical system, and another laser beam is incident on a condenser lens, reflected from the optical disc, and guided to the focus and tracking error signal detection optical system. To use. Further, an optical disk device according to the present invention comprises the optical disk, the optical head, an optical disk rotating means, a laser light source driving circuit for the optical head, and an optical deflection element driving circuit provided in the optical head. , A focus and tracking servo circuit, and a reproduction signal detection circuit.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing the principle of an optical disk recording / reproducing / erasing method according to the present invention. In FIG. 1, the optical disk 10 is irradiated with two focused laser beams. The condensed laser beam 1 is for recording / reproducing and erasing, and the condensed laser beam 2 is for detecting focus and tracking error signals. The optical disc 10 has a guide groove 11 for tracking a laser beam.
And a flat portion 12 used for recording are formed adjacent to each other.
The focused laser beam 1 for recording / reproducing is used for the flat portion 12 of the disk.
The focused laser beam 2 for focus and tracking error signal detection is applied to the guide groove 11. The focus and tracking error signals are detected by the known error signal detection method in the optical disc using the reflected light from the guide groove 11. On the other hand, the recording / reproducing erasing condensed laser beam 1 is applied so as to obliquely scan the disk flat portion 12. While the optical disc 10 moves in the rotation direction 50, the laser beam 1 moves at a high speed in the scanning direction 51 while maintaining a constant angle with respect to the rotation direction 50 to perform recording / reproduction / erasure. This is the feature of the present invention.

Here, the guide groove 11 formed in the disk
Is set to a width of about ½ of the spot diameter of the focused laser beam 2 and the depth is set to about ⅛ of the wavelength of the focused laser beam 2, whereas the width of the disk flat portion 12 is set to The spot diameter is set to be four times as large as the spot diameter of the optical laser beam 1 or more.

FIG. 2 is a diagram showing recording bits formed on the disc. At the time of recording, the laser beam 1 is applied so as to scan the flat portion 12 of the disc obliquely, so that the recording bit string 13 formed on the flat portion 12 with respect to the disc rotation direction 50 as shown in FIG. It has a constant angle and spreads in the width direction of the flat portion 12. Here, the laser beam 1 is scanned in the width direction of the flat portion 12,
The scanning direction may be a constant direction, such as right to left or left to right, as shown in FIG. 2A, or a method of changing the scanning direction for each scanning as shown in FIG. 2B. A pre-formatted bit string 14 including sector information / synchronization signal is previously formed in the guide groove 11. By using this pre-formatted signal, it is possible to secure the synchronization of recording / reproduction / erasure and to correct the laser beam position deviation, whereby the laser beam 1 can be accurately scanned on the flat portion 12.

In this method, the transfer speed of the recording data is determined by the scanning speed of the laser beam 1 rather than the linear speed when the disk rotates. This laser beam scanning speed depends on the capability of the optical deflecting element used for scanning, but the linear velocity is 5
About 0 m / s can be easily realized. This method can easily achieve high linear velocity recording as compared with a conventional optical disc recording method without a laser beam scanning mechanism, and thus a high data transfer rate can be realized.

FIG. 3 is a diagram showing the structure of the optical head according to the present invention. As described above, the present invention requires two laser beams for recording / reproducing / erasing and a laser beam for detecting focus / tracking error signals. In order to realize this, the optical head has two laser beam sources. Is provided. In FIG. 3, a laser light source 31 is a recording / reproducing / erasing laser. The emitted light from the laser 31 passes through the collimator lens 32 and the beam shaping prism 33 to become circular parallel light, and then enters the light deflection element 34. As the focused beam of laser light scans the flat portion 12 of the disk,
Here it is deflected at high speed. A typical deflecting element used here is an AO deflector utilizing the acousto-optic effect.
After passing through the optical deflector 34, the laser light passes through the beam splitters 35 and 36, enters the condenser lens 37 having the servo actuator mechanism, and is condensed on the disk 10.
Here, when an optical disk for write-once recording or phase change recording is used, as shown in FIG. 4, the beam splitter 35 includes a deflecting beam splitter 38 and a quarter wavelength plate 39.
A combined isolator is used. If a magneto-optical recording disk is used, the beam splitter 35
For this, a Kerr rotation angle multiplication type beam splitter having different reflection characteristics for P-polarized light and S-polarized light is used. Further, as the beam splitter 36, one having a characteristic of transmitting 100% of the wavelength of the laser light 1 is adopted. The reflected light from the disk 10 is reflected by the beam splitter 35 and guided to the reproduction signal detection optical system 40.

On the other hand, a laser light source 41 is used for the laser light 2 for detecting the focus and tracking error signals. The light emitted from the laser 41 is collimated by a collimator lens 42,
After it becomes circular parallel light through the beam shaping prism 43, it enters the optical disk 10 through the polarization beam splitter 44, the quarter-wave plate 45, the beam splitter 36, and the condenser lens 37. This laser light 2 is focused on the guide groove of the optical disc. The reflected light is reflected by the polarization beam splitter 44.
And is guided to the focus and tracking error signal detection optical system 46. Here, as the beam splitter 36, one having a characteristic of reflecting almost 100% of the wavelength of the laser light 2 is used.

FIG. 5 is a diagram showing the configuration of the optical disk device according to the present invention. This optical disk device comprises an optical disk 10, an optical head 30, and a rotating means 6 for the optical disk 10.
1, a laser light source driving circuit 62 of the optical head 30, and a driving circuit 63 of the optical polarization element 34 provided in the optical head.
And a focus and tracking servo circuit 64,
A reproduction signal detection circuit 65 is provided.

Next, in order to understand the effectiveness of the optical disc recording / reproducing / erasing method according to the present invention, an optical disc based on the configuration shown in FIG. 1 and a configuration shown in FIGS. An optical head was produced. The produced optical disc is
A phase change recording film is formed on a glass substrate having a diameter of 130 mm. The substrate used was one in which a guide groove and a flat portion were previously formed in a spiral shape with a radius of 30 mm to 60 mm using an ultraviolet curable resin. The width of the guide groove is 0.6μ
m and the depth was designed to be 75 nm. A pre-formatted bit string including sector information and a sync signal was previously formed in the guide groove. The width of the flat part is
It was set to 15 μm. By sputtering on this substrate,
ZnS + SiO ₂ dielectric protective film, GeSbTe recording film,
A ZnS + SiO ₂ dielectric protective film and an Al reflective film were continuously formed. Further, after applying an ultraviolet curable resin on the reflective film, the disc and the glass substrate were bonded together. The optical head used was one equipped with a semiconductor laser with a wavelength of 830 nm and an output of 40 mW for recording and a semiconductor laser with a wavelength of 670 nm and an output of 10 mW for servo. The optical polarization element for scanning the recording laser focused beam on the flat portion of the disk includes a driving frequency of 60 to 100 MHz and a deflection angle of 11 to 1
An AO deflector having a characteristic of 7 mrad was used. A lens having a numerical aperture of 0.5 and a focal length of 3 mm was used as the condenser lens. At this time, the condensed beam could be scanned with a width of 18 μm on the disk. The spot position of the servo laser was aligned with the guide groove, and the spot position of the recording laser was aligned with the center of the flat portion of the disk (the position 7.5 μm from the guide groove) when the AO deflector drive frequency was 80 MHz.

Next, while rotating the disk at a linear velocity of 5 m / s, the scanning direction of the recording laser is tilted by 30 ° with respect to the width direction of the flat portion, and the drive frequency of the AO deflector is changed to change the guide groove. The length of 17.3 μm from one end to the other end of the flat part in contact with was scanned for 346 ns. After the scanning was completed, a blank of 54 ns was provided and the laser beam was returned to the scanning start point. During this time, the disk moves 2 μm in the rotation direction within 400 ns, so the next scanning portion is 2 μm.
leave m. That is, the scanning pitch is 2 μm. Recording is performed over the entire surface of the disc by repeating this series of operations. Here, the linear velocity of the disk is 5 m / s, but the linear velocity of the laser beam being scanned is 50 m / s.
Has become.

Therefore, in order to confirm the high linear velocity recording which is a feature of the present invention, recording laser light power was modulated at 20 MHz (duty ratio 50%), and recording was tried in the laser beam scanning direction. As a result of confirming the recording beam with a transmission electron microscope, it was confirmed that amorphous recording bits having a bit length of 2.5 μm were satisfactorily formed continuously along the scanning direction. In addition, when reproduction was performed using the synchronization signal from the pre-formatted bit formed in the guide groove, a good reproduction signal was obtained. Similarly, DC erasing was also possible. One-beam overwrite, which is one of the characteristics of phase change recording, was also confirmed.

In the embodiment of the present invention, an example of a disc having a phase change recording film is shown, but it is also effective for a disc having another recording film, that is, a magneto-optical recording film or a write-once recording film. Needless to say.

[0023]

As described above, according to the present invention, even though the disc itself is rotated at a low linear velocity, high linear velocity recording is possible, and even if a plastic substrate having low rigidity is used, This has the effect of recording linear velocity.
Further, the head configuration is simpler than that of a multi-beam head or a multi-head drive, and a low-cost drive configuration is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of an optical disc recording / reproducing / erasing method according to the present invention.

FIG. 2 is a diagram showing the principle of an optical disk recording / reproducing / erasing method according to the present invention.

FIG. 3 is a diagram showing a configuration of an optical head for an optical disc according to the present invention.

FIG. 4 is a diagram showing another configuration of the optical head for an optical disc according to the present invention.

FIG. 5 is a diagram showing a configuration of an optical disc device according to the present invention.

[Explanation of symbols]

1, 2 laser light 10 optical disc 11 Tracking guide groove 12 Flat part 13 Recording bit string 14 pre-formatted bit string 30 optical head 31,41 Laser light source 32,42 Collimating lens 33,43 Beam shaping prism 34 Optical deflection element 35,36 Beam splitter 37 Condensing lens 38,44 Polarization beam splitter 39,45 1/4 wave plate 40 Playback signal detection optical system 46 Focusing and tracking error signal detection optical system 50 Optical disc rotation direction 51 Laser light scanning direction 61 Optical Disk Rotating Means 62 Laser light source drive circuit 63 Optical deflection element driving circuit 64 Focus and tracking servo circuit 65 Playback signal detection circuit

Claims (4)

[Claims] 1. A recording / reproducing / erasing method of an optical disc for performing recording / reproducing / erasing of information by using a laser beam, wherein at the time of recording / reproducing / erasing, a laser beam deflected in a fixed angle direction with respect to a rotation direction of the optical disc is scanned. An optical disk recording / reproducing / erasing method characterized by irradiating an optical disk. 2. An optical disk used for carrying out the optical disk recording / reproducing / erasing method according to claim 1, comprising a guide groove for tracking a laser beam and an information recording flat portion adjacent to the guide groove. An optical disc in which the width of the flat portion is wider than the width of the guide groove, and the flat portion and the guide groove are formed in a concentric or spiral shape. 3. An optical head for an optical disk used for carrying out the optical disk recording / reproducing / erasing method according to claim 1, comprising at least two laser light sources, an optical deflecting element, a condenser lens, and reproduction signal detecting optics. System and a focus and tracking error signal detection optical system, the laser light from the one laser light source is incident on the optical disk through the optical deflection element and the condenser lens, and the reflected light from the optical disk is the reproduction signal. An optical head for an optical disk, which is guided to a detection optical system, and another laser beam is incident on a condenser lens and reflected from the optical disk, and then is guided to the focus and tracking error signal detection optical system. 4. An optical disk device used for carrying out the optical disk recording / reproducing / erasing method according to claim 1, wherein the optical disk according to claim 2, the optical head according to claim 3 and an optical disk for rotating the optical disk. Rotation means,
An optical disc comprising a laser light source driving circuit for driving the laser light source, an optical deflecting element driving circuit for driving the optical deflecting element, a focus and tracking servo circuit, and a reproduction signal detecting circuit. apparatus.