JPH10188460A - Optical disk device and optical disk recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device that is provided with a function discriminating the substrate thickness of a magneto-optical disk and can perform adequate recording and/or reproducing processing in accordance with substrate thickness. SOLUTION: An optical head 10 reads out a mark pattern indicating thickness of a transparent substrate from a recording layer of a magneto-optical disk 2 housed in a disk cartridge 1 freely rotatably. A system controller 29 switches and controls the recording and/or reproducing mode of the magneto-optical disk 2, for example, an object lens 11 or an object lens 12 having different numerical apertures NA in accordance with read-out output from the optical head 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus and an optical disk recording medium for recording and / or reproducing information signals by irradiating a recording layer of an optical disk with light through a transparent substrate.

[0002]

2. Description of the Related Art In an optical recording medium such as an optical disk, an information signal is recorded and / or reproduced by a laser beam irradiated on a recording layer via an optically transparent substrate made of, for example, polycarbonate. This optical recording medium has been widely spread as a recording medium for computers, package media such as audio and video, and has also been increasing in density.

As one method of increasing the density, it is conceivable to increase the numerical aperture NA of the objective lens. This is because the resolution is improved because the beam spot formed on the optical recording medium is small. However, if the NA is increased, the allowable range with respect to the tilt of the disk becomes narrow.

[0004] Therefore, it has been considered to make the substrate thinner. For example, the substrate of a magneto-optical disk having a diameter of 5.25 inches is 1.2 mm at present, but it is conceivable to reduce this by half to 0.6 mm. If the substrate is made thinner, a margin of error with respect to the inclination of the disk can be obtained to some extent even when the NA is increased.

For this reason, as described above, the substrate is 1.2 m
There has been a demand for an optical disk device capable of recording / reproducing information signals for both a magneto-optical disk of m and a magneto-optical disk of 0.6 mm.

[0006]

As described above, in the case where a magneto-optical disk having a substrate thickness of 0.6 mm is used to increase the recording density, a magneto-optical disk having a current 1.2 mm-thick substrate is used. Although it is necessary to be compatible with the disk, there has not been considered an optical disk apparatus having a function of determining the thickness of a magneto-optical disk having a diameter of 5.25 inches.

Further, the magneto-optical disk having a diameter of 5.25 inches housed in the disk cartridge has not been provided with a mechanism for determining the thickness.

The present invention has been made in view of the above circumstances, and has a function of determining the substrate thickness of a magneto-optical disk, and is capable of performing appropriate recording and / or reproduction processing according to the substrate thickness. The purpose is to provide the device.

Another object of the present invention is to provide an optical disk recording medium having a mechanism suitable for determining the thickness of a substrate.

[0010]

In order to solve the above-mentioned problems, an optical disk apparatus according to the present invention reads a mark pattern indicating a thickness of a transparent substrate written on a recording layer of an optical disk by a reading means, and reads the mark pattern. The control means switches the recording and / or reproduction mode for the optical disc according to the output.

Further, in order to solve the above-mentioned problems, an optical disk recording medium according to the present invention is provided with a mark pattern for determining the thickness of a transparent substrate on a recording layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a magneto-optical disk device as an embodiment of an optical disk device according to the present invention and a magneto-optical disk as an embodiment of an optical disk recording medium will be described with reference to the drawings.

The magneto-optical disk drive irradiates a recording layer of, for example, a 5.25 inch diameter magneto-optical disk accommodated in a cartridge with a laser beam through a transparent substrate made of, for example, polycarbonate to record and / or record information signals. Or regenerate.

As shown in FIG. 1, the magneto-optical disk drive comprises: an optical head 10 for reading a mark pattern indicating the thickness of the transparent substrate from a recording layer;
And a system controller 29 for controlling the switching of the recording and / or reproduction mode for the magneto-optical disk 2 in accordance with the read output from the system. Here, the disk cartridge 1 that houses the magneto-optical disk 2 is an embodiment of the optical disk recording medium.

As shown in FIGS. 2 and 3, the disk cartridge 1 has one surface (hereinafter referred to as a surface) 2.
_The magneto-optical disk 2 to which _A and the other surface (hereinafter referred to as the back surface) _2B are bonded is rotatably housed inside. FIG. 2 shows the front side of the disc cartridge 1.
FIG. 3 shows the back surface. When this disk cartridge is inserted into a cartridge holder (not shown) of the magneto-optical disk device while looking at "A" shown on the front surface, the shutter 7 is opened by a shutter opening / closing mechanism (not shown) of the device and the shutter 7 is opened. Parts _4A and _4B are exposed. When the shutter is completely opened, that is, when the disk cartridge 1 is completely housed in the cartridge holder, the mounting of the disk cartridge 1 in the apparatus is completed.

At this time, the hub 3 _A on the A surface 2 _A side of the magneto-optical disk 2 covered by the shutter 7 on the back side of the disk cartridge 1 is connected to the motor shaft of the spindle motor 28 through the through hole 6 _A. The magneto-optical disk 2 is mounted on a spindle motor 28 in close contact with and held by a turntable 31 with a magnet provided at the upper end.

[0017] In this state, the A side 2 of the magneto-optical disk 2_A
And / or reproduction of the magneto-optical disk device on the side
Becomes possible. That is, in the direction of the arrow shown in FIG.
With the “A” facing up, insert the disk cartridge 1
When inserted into the cartridge holder, it is actually shown in FIG.
Opening 4_AA side 2 on the side_AIs exposed.

On the other hand, when this disk cartridge 1 is inserted into the cartridge holder of the magneto-optical disk device in the direction of the arrow while looking at "B" shown on the back surface, the shutter 7 is opened by the shutter opening / closing mechanism, and the shutter 7 is opened. Part 4 _A
And 4 _B are exposed, but this time, the hub 3 _B of B surface 2 _B side of the magneto-optical disc 2 which was covered with the shutter 7 on the surface side of the disk cartridge 1, the spindle motor via a hole 6 _B The magneto-optical disk 2 is mounted on a spindle motor 28 in close contact with and held by a turntable 31 with a magnet provided at the upper end of a motor shaft 28.

In this state, the B surface 2 _{B of the} magneto-optical disk 2
The recording and / or reproduction of the magneto-optical disk device can be performed on the side. That is, when the disk cartridge 1 is inserted into the disk cartridge holder in the top "B" in the direction of the arrow shown in FIG. 3, it is actually exposed surface B 2 _B in the opening 4 _B side shown in FIG. 2 .

The magneto-optical disk 2 has A-side surfaces 2 _A and B
Forming a surface 2 _B as shown in FIG. That is, for example, on a transparent substrate 61 made of polycarbonate, a dielectric layer 62 made of a SiN film and an MO layer 6 made of TbFeCo
3. A dielectric layer 64, a reflective film 65 made of Al, and a protective film 66 made of UV resin are formed. Then, the protective films 66 are bonded together to form a bonded disk.

As shown in FIG. 1, when the disk cartridge 1 is inserted into the disk cartridge holder of the magneto-optical disk drive in the direction of the arrow while looking at "A" as described above, the A surface 2 of the magneto-optical disk 2 laser light is irradiated from the optical head 10 to the _a side through the opening 4 _a.

The optical head 10 has two objective lenses 11
, 12, a two-axis unit 13 for switchably holding the two objective lenses 11 and 12, a mirror 14, and a fixed optical system 15.

The objective lens 11 can record and / or reproduce information signals optimally on a magneto-optical disk having a numerical aperture NA of, for example, 0.6 and a transparent substrate 61 of 0.6 mm. On the other hand, the objective lens 12 has a numerical aperture N
It is possible to optimally record and / or reproduce information signals on a magneto-optical disk in which A is set to 0.55 and the transparent substrate 61 is set to 1.2 mm, for example.

As shown in FIG. 5, the fixed optical system 15 includes a laser diode 16 for diffusing and emitting a writing laser beam or a reproducing laser beam, a collimator lens 17 for parallelizing these laser beams, A beam splitter 18 that transmits the laser light in the direction of the mirror 14 and reflects return light, which will be described later, and changes a Kerr rotation angle of the return light reflected by the reflection surface 18a of the beam splitter 18 into a light intensity change. A polarization beam splitter 19, a photodiode 20 that converts one return light transmitted through the polarization beam splitter 19 into an electric signal, and converts the other return light reflected by the reflection surface 19a of the polarization beam splitter 19 into an electric signal. Photodiode 21 to convert
And

For example, when an information signal is recorded on the _A side _2A side, a system controller 29 drives a laser driver 32 to write a laser beam to the laser diode 16 in the fixed optical system 15 of the optical head 10. Supply drive current. At this time, the magnetic head driver 33 supplies a drive current for giving magnetization in a certain direction to the magnetic head 34 composed of an electromagnet.

In the initial state, the direction of magnetization of the MO film 63 is, for example, downward. Here, an upward magnetic field is applied from the outside by the magnetic head 34, and the optical head 10 irradiates a writing laser beam at the timing of recording the information signal. Become warm point the writing laser beam A surface 2 _A side MO film 63 of the magneto-optical disc 2 hits found
When the Curie point is reached, the coercive force of the MO film 63 decreases, and a portion where the magnetization is reversed upward due to the action of the external magnetic field by the magnetic head 34 is formed, and an information signal is recorded.

When reproducing information from the magneto-optical disk, the laser diode 16 of the optical head 10
System controller 29 via laser driver 32
And emits a laser beam for reproduction.

The laser beam for reproduction is irradiated onto the MO layer through the transparent substrate 61. The laser beam for reproduction that has entered the MO layer 63 is reflected so that the plane of polarization slightly rotates by about 0.2 to 0.4 degrees depending on the direction of magnetization, and becomes return light. This return light passes through the objective lens 11 or the objective lens 12, is reflected by the mirror 14, and is reflected by the fixed optical system 1.
Return to 5. In the fixed optical system 15, the change in the Kerr rotation angle (± θ) of the return light is converted into a light intensity change by the polarization beam splitter 19, and guided to the photodetectors 20 and 21.
Take it out as an electrical signal.

The electric signals detected by the photo detectors 20 and 21 of the fixed optical system 15 are supplied to a matrix circuit 23. The matrix circuit 23 is constituted by, for example, a digital signal processing unit (DSP).
An F signal is generated and supplied to the output terminal 35. The matrix circuit 23 generates a focus servo signal and a tracking servo signal from the focus error signal and the tracking error signal, and
And the tracking driver 25. In addition, a thread servo signal and a spindle servo signal are generated and supplied to the thread driver 26 and the spindle driver 27.

The focus driver 24 supplies a drive current to the focus coil of the biaxial unit 13 according to the focus servo signal, and drives the objective lens 11 or 12 in the focus direction, that is, in a direction parallel to the optical axis. The tracking driver 25 supplies a drive current to the tracking coil of the biaxial unit 13 according to the tracking servo signal, and drives the objective lens 11 or 12 in the track direction, that is, in a plane direction orthogonal to the optical axis.

The thread driver 26 drives the biaxial portion 13 largely in a plane direction orthogonal to the optical axis according to the thread servo signal. Spindle servo driver 27
Drives the spindle motor 28 to rotate at CAV or CLV according to the spindle servo signal. Such servo processing is performed not only at the time of the reproduction processing but also at the time of the recording processing.

[0032] the disc cartridge 1, as shown in FIGS. 2 and 3, like the media identification hole group 9 with respect to the surface A 2 _A side-erase prevention hole 8 erroneous for A face 2 _A side, B side 2 _B-side A medium identification hole group 11 for the _B side 2B side is provided in the same manner as the erroneous erasure prevention hole 10 for.

[0033] Here, the mark pattern optical pickup 10 reads from the A-side 2 _A and B side 2 _B of the magneto-optical disc 2, as shown in FIG. 6 of the magneto-optical disk having a substrate thickness t = 0.6 mm recorded Peripheral area 4 of format on layer
1 or SFP (Standared Formatted)
Part) PFP in zone 44 or 52 or inner peripheral area 50
(Phase Encoded Part) is pre-written in the zone 53 as prepits. Since a magneto-optical disk having a substrate thickness of t = 1.2 mm is already on the market, it is desirable to provide the magneto-optical disk with a newly created t = 0.6 mm.

A-side 2 _A and B-side 2 of magneto-optical disk 2
_B has the format of the recording layer as shown in FIG. Since the magneto-optical disk 2 has a recording capacity of, for example, 2.6 GB, it is lead-in from the outer peripheral portion 40 side.

Inside the zone 42 which is the outermost peripheral area,
A lead-in zone 43 is formed, an SFP zone 44 serving as a control track is formed inside the lead-in zone 43, a medium manufacturer zone 45 is formed inside the SFP zone 44, and a user recording zone 46 is formed. Here, detailed recording conditions, the MCVA method, the variable track pitch method, and the like are written in the SFP, and the SFP is identified by the apparatus.

On the inner peripheral side, as shown in a region 50, a medium manufacturer zone 51 is formed inside the user zone 46, an SFP zone 52 is formed inside the zone 51, and a control track is formed inside the SFP zone 52. PFP zone 53
Are formed, and a reflectance adjustment zone 54 and a clearance zone 55 are formed. Here, in the PFP zone 53, the type of medium, modulation method, rotation mode, EC
The C mode, reproduction laser power, recording position, and the like are recorded in advance.

Further, inside the clearance zone 55, a clamping zone 56, a hub 57, a magnetic metal 58
Are formed. A bearing hole 59 for receiving a shaft from a spindle motor is formed in the center of the magnetic metal 58.

Here, as described above, the mark pattern indicating the substrate thickness is written as prepits in, for example, the SFP zone or the PFP zone of the recording layer of the magneto-optical disk having the substrate thickness t = 0.6 mm.

As the mark pattern, a number of tracks (for example, a track width of 100 μm or more) which are not so high in frequency that can cover MTF (Modulation Transfer Function) of different objective lenses and can be read without applying a tracking servo. It is desired that the data is written over the range This is related to the fact that the eccentricity of the disk is at most about 50 μm. Therefore, it is most desirable to write in a PFP zone having a width of 500 μm.

The optical head 10 attempts to read the mark pattern from the recording layer of the rotating disk by turning on only the focus by the biaxial unit 13. When the mark pattern is read, a read output is supplied to the system controller 29 via the matrix circuit 23. The system controller 29 determines, for example, that a magneto-optical disk having a transparent substrate thickness t = 0.6 mm is mounted, selects the objective lens 11 as the biaxial unit 13, and sets it on the optical path.

Then, the system controller 29 records and / or reproduces information signals on the magneto-optical disk by using an objective lens having a numerical aperture NA suitable for the thickness t of the transparent substrate.

The control performed by the system controller 29 is shown in the flowchart of FIG. 7, and the detailed operation of the magneto-optical disk device will be described with reference to FIG.

First, in step S1, the objective lens 11 for the substrate thickness t = 0.6 mm is set on the biaxial portion 13.
When the disk cartridge 1 containing the magneto-optical disk 2 is inserted into the disk cartridge holder of the apparatus in step S2, the system controller 29 turns on the spindle motor 28, turns on the laser diode 16, and turns on the focus driver 24.

Then, the system controller 29 determines whether or not the optical head 10 has read the mark pattern in step S4. If the mark pattern has been read, the process proceeds to step S5 where the SFP is read, and in step S6 the transparent substrate thickness t is read.
For example, processing states such as a modulation method, a sector length, a rotation speed, a reflectance, a reading laser power, an AGC, and a writing laser power are set in accordance with a magneto-optical disk having a size of 0.6 mm.

When the setting of the recording and / or reproducing mode for the transparent substrate thickness t = 0.6 mm has been completed as described above, the system controller 29 controls the components shown in FIG. 1 and performs recording and / or reproducing in step S7. To start.

On the other hand, if it is determined in step S4 that the optical head 10 could not read the mark pattern, the system controller 29 proceeds to step S8 and turns off the focus. Then, in step S9, the substrate thickness t = 1.2
After the objective lens 12 for mm is set on the biaxial portion 13 so as to be set on the optical path, the focus is turned on. Thereafter, the SFP is read in step S10, and the process proceeds to step S10.
In step 11, a modulation method, a sector length, a rotation speed, a reflectance,
The processing state such as reading laser power, AGC, writing laser power, etc. is set.

When the setting of the recording and / or reproducing mode for the transparent substrate thickness t = 1.2 mm is completed as described above, the system controller 29 controls each part shown in FIG. 1 and performs the recording and / or reproducing in step S7. To start.

As described above, in the magneto-optical disk device, the thickness of the substrate can be determined by reading out the mark pattern written in advance on the magneto-optical disk by the optical head 10, so that the objective suitable for each thickness can be determined. By selecting a lens, it becomes possible to support a plurality of discs. Therefore, it is possible to achieve both high density and compatibility.

In the magneto-optical disk drive according to the embodiment of the present invention, recording and recording of information signals are performed on a disk cartridge 1 in which two 5.25 inch magneto-optical disks are stuck and rotatably housed. Although the recording / reproduction is performed, the recording and / or reproduction of the information signal may be performed on a disk cartridge in which only one 3.5-inch or 5.25-inch magneto-optical disk is rotatably stored.

Also, a magneto-optical disk not housed in a disk cartridge can be used.

Further, the mark pattern may be read only by focusing on and may be written in another zone in advance if the frequency is not too high.

[0052]

According to the optical disk apparatus of the present invention, a mark pattern indicating the thickness of the transparent substrate written on the recording layer of the optical disk is read by the reading means, and the control means records and / or writes on the optical disk according to the output. Alternatively, since the reproduction mode is switched, appropriate recording and / or reproduction processing can be performed according to the substrate thickness of the optical disk.

In the optical disk recording medium according to the present invention, since the mark pattern for determining the thickness of the transparent substrate is provided on the recording layer, the apparatus can easily determine the substrate thickness.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an optical disk device of the present invention.

FIG. 2 is an external view of one surface side of the embodiment of the optical disk recording medium of the present invention.

FIG. 3 is an external view of the other surface side of the embodiment of the optical disc recording medium of the present invention.

FIG. 4 is a sectional view of a magneto-optical disk accommodated in the embodiment of the optical disk recording medium.

FIG. 5 is a detailed configuration diagram of a fixed optical system used in the embodiment shown in FIG. 1;

FIG. 6 is a diagram showing a format on a recording layer of a magneto-optical disk in an embodiment of the optical disk recording medium of the present invention.

FIG. 7 is a flowchart for explaining a detailed operation of the embodiment shown in FIG. 1;

[Explanation of symbols]

1 disk cartridge, 2 magneto-optical disk, 2 _A
Front, _2B back, 10 optical head, 13 biaxial part, 15 fixed optical system, 29 system controller

Claims (3)

[Claims] 1. An optical disc apparatus for irradiating a recording layer of an optical disc with light through a transparent substrate to record and / or reproduce an information signal, wherein a mark pattern indicating a thickness of the transparent substrate is read from the recording layer. An optical disc device comprising: means for controlling a recording and / or reproduction mode for the optical disc in accordance with a read output from the read means. 2. The optical disk device according to claim 1, wherein said optical disk is a magneto-optical disk. 3. An optical disc recording medium characterized in that a mark pattern for judging the thickness of a transparent substrate is provided on a recording layer.