JPH0935351A - Magneto-optical recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a light emission control and to reduce power consumption while maintaing a recording density at a high density by combining a magnetic field modulation and a pulse generation in a magneto-optical recording. SOLUTION: The signal from an optical head 2 consisting of a laser diode and a condenser lens, etc., is made to be PRF and MO signals via an I-V converter 3 to respectively subjected to signal processings and they are transmitted to an R/W 17. The R/W 17 modulates recording data into non-conversion section length control codes to send them to a control circuit 14 and data to be transmitted from the control circuit 14 are encoded and a PPD circuit 18 is controlled, based on the encoded data. The PPD circuit 18 controls phases of the magnetic field generation of a magnetic head 8 and the light emission of the laser diode of the optical head 2 by controlling a magnetic head driver 6 and a laser driver 4. Then, the laser diode performs one time pulse light emissions per plural channel bits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a magneto-optical recording apparatus for applying a modulation magnetic field to a magneto-optical recording medium and irradiating a condensed light beam to record an information signal.

[0002]

2. Description of the Related Art Conventionally, a so-called magneto-optical recording medium having a signal recording layer made of a magnetic material has been proposed. Then, as this magneto-optical recording medium, a magneto-optical disk constituted by having the above-mentioned signal recording layer on a disk-shaped substrate has been proposed.

In this magneto-optical recording medium, a light beam focused on a predetermined area on the signal recording layer is irradiated to heat the area to a temperature higher than the so-called Curie temperature of the material forming the signal recording layer. By applying a modulation magnetic field modulated according to the recording data, the magnetization direction of the signal recording layer is made to follow the modulation magnetic field in the cooling process,
Data recording is performed. The method of recording data in this way is called a magnetic field modulation method.

A magneto-optical recording device has been proposed which records and reproduces information signals using the magneto-optical disk as a recording medium.

This magneto-optical recording apparatus includes a rotating operation mechanism for rotating the magneto-optical disk while holding the center of the magneto-optical disk, an optical head (optical pickup device) for irradiating the magneto-optical recording medium with a light beam. And a magnetic head for applying a modulation magnetic field to the magneto-optical recording medium.

In the magneto-optical recording apparatus, considering the ease of moving the reading position of the recording signal on the magneto-optical disk in the radial direction of the magneto-optical disk (so-called seek operation), CAV (Contin) is used.
It is desirable to use a smooth angular velocity (i.e., angular angular velocity) rotation. On the other hand, in order to increase the density of the recording signal on the magneto-optical disk, it is better to keep the linear density of the recording data constant.

Therefore, there has been proposed a zone system (zone-CA) in which recording / reproduction is performed while the linear density of recorded data is kept constant while CAV rotation is performed.
V, M-CAV). In this zone system, the signal recording area of the magneto-optical disk is divided into a plurality of zones according to the distance from the center of the magneto-optical disk. That is, the zones are arranged in a concentric circle in the radial direction of the magneto-optical disk.

In order to increase the recording density of the magneto-optical disk, it has been proposed in the magnetic field modulation method that the light beam emitted by the optical head is pulsed light by pulsed light emission.

[0009]

By the way, in the above-mentioned zone type magneto-optical recording apparatus, the recording / reproducing channel clock (Channel Clock) is provided on the outer peripheral side as compared with the inner peripheral side of the signal recording area. )
Is faster.

For example, the diameter of the magneto-optical disk is 120 m.
In the case of m, the signal recording area is an area having a radius of 58 mm rather than a radius of 24 mm. When the linear density of the recorded data on this magneto-optical disk is made constant, the recording / reproducing channel clock depends on the linear velocity, and at the outermost circumference,
It is 2.4 times the innermost circumference (= 58/24).

When the magneto-optical disk is used as a digital video disk (DVD) on which digital video data is recorded, the data transfer rate is 10
I want to secure about Mbps (Mbit / sec). When the data transfer rate is 10 Mbps in the inner peripheral part of the signal recording area, it is 24 Mbps in the outer peripheral part. Here, EFM (Eight to Fo) is used to modulate the recording data.
In the case of using a modulation method such as U.T.en Modulation), the channel clock is about 50 MHz in the outer peripheral portion of the signal recording area, which is double the inner peripheral portion.

When the channel clock has such a high speed, it becomes difficult to drive and control both the magnetic field modulation in the magnetic head and the pulsed light emission in the optical head.

Therefore, the present invention is proposed in view of the above-mentioned circumstances, and adopts CAV (constant angular velocity) rotation and constant linear density of recorded data in a magneto-optical disk by using a zone system. Another object of the present invention is to solve the problem of providing a magneto-optical recording device in which magnetic field modulation in a magnetic head and pulse light emission in an optical head can be easily performed and data can be recorded favorably.

[0014]

A magneto-optical recording apparatus according to the present invention is a magneto-optical recording medium that modulates recording data into a non-inverted section length limiting code, and a modulation magnetic field corresponding to the non-inversion section length limiting code. A magnetic field generating means for applying to the recording medium and a luminous flux irradiating means for condensing and irradiating the luminous flux on the region of the magneto-optical recording medium to which the modulation magnetic field is applied are provided.

The non-inverted section length limit (RLL (Run
The length limited) code is a code in which the minimum inversion interval (the lower limit of the length of the non-inversion section) is limited to span a plurality of channel bits. Further, in this non-inverted section length limiting code, the maximum inversion interval (upper limit of the length of the non-inverted section) is also limited to the length of a predetermined number of channel bits.

In this magneto-optical recording apparatus, the light emitting means of the luminous flux irradiating means emits pulsed light once for a plurality of channel bits.

[0017]

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

In this embodiment, the magneto-optical recording apparatus according to the present invention writes recorded data to a magneto-optical disk which is a magneto-optical recording medium by using so-called magnetic field modulation method and zone method, and It is configured as a device for reading the recording data recorded on the magneto-optical disk.

The magneto-optical disk is irradiated with a light beam focused on a predetermined area on the signal recording layer to heat the area above the so-called Curie temperature of the material forming the signal recording layer, and to record data. The recording medium is capable of recording data by applying a modulated magnetic field that is modulated accordingly to cause the magnetization direction of the signal recording layer to follow the modulated magnetic field in the cooling process.

In this magneto-optical recording apparatus, the recording data recorded on the magneto-optical disk is a non-reversed section length limiting code, so-called RLL (Run Length).
Limited) code, for example, EFM
(Eight to Fourteen Modula
NRZI (Non Retu)
Data in which the minimum inversion interval (shortest mark length) and the maximum inversion interval (longest mark length) are regulated by the rn to Zero Inverted) code and the upper and lower limits of the number of consecutive "0" s are limited. Is.

The zone system adopted in this magneto-optical recording apparatus, as shown in FIG. 2, sets the signal recording area of the magneto-optical disk 9 in accordance with the distance from the center of the magneto-optical disk 9. , Multiple zones Z ₁ , Z ₂ , Z _{3
·· Z n, Z n + 1} , Z n + 2, Z n + 3 is divided into ..., each zone _{Z 1, Z 2, Z 3} ··· Z n, Z n + 1, Z n + 2 , Z _{n + 3} ...
In, the recording data with a constant linear density is written. Each of the zones Z ₁ , Z ₂ , Z ₃ ... Z _n , Z
_{The n + 1} , Z _{n + 2} , Z _{n + 3,} ... Are arranged in a concentric pattern in the radial direction of the magneto-optical disk 9.

Each of the zones Z ₁ , Z ₂ , Z ₃ ... Z _n , Z
_The recording data recorded on the recording tracks at _{n + 1} , Z _{n + 2} , Z _{n + 3,} ... Address area (address area) (header) as shown in FIGS. 23 and the data area (data a
real) 24 and a plurality of sectors (Sector)
It consists of. In addition, the address area 23
As shown in FIG. 3, a sector mark (SM) 25 used for sector detection, data (VFO1) 26 used for pull-in by a PLL circuit described later, a first address mark (AM1) 27 used for address detection, a first An address (Address1) 28, data (VFO2) 29 used for pulling in by the PLL circuit, a second address mark (AM2) 30 used for address detection, and a second address (Address2) 31 are included.

The address area 23 is an area in which signals are previously written by means of prepits formed by means such as injection molding when the magneto-optical disk 9 is produced. The data area 24 is an area where the user of the magneto-optical disk 9 writes an information signal by using the magneto-optical recording device.

Each of the zones Z ₁ , Z ₂ , Z ₃ ... Z _n , Z
_{In n + 1} , Z _{n + 2} , Z _{n + 3,} ..., Since the linear densities of the recording data to be recorded are equal to each other, the address area 23 is, as shown in FIG. It is formed at a position transitioning in the circumferential direction of the magneto-optical disk 9 with respect to 23.

As shown in FIG. 3, this magneto-optical recording apparatus has a rotary operation mechanism 7 for rotating the magneto-optical disk 9 while holding the central portion of the magneto-optical disk 9. This magneto-optical recording device is provided with an optical block section (Optical
Block) 1.

The optical block section 1 has a magnetic head 8 which constitutes a magnetic field generating means for applying a magnetic field to the signal recording layer of the magneto-optical disk 9 which is rotated by the rotation operation mechanism 7.

The magnetic head 8 is controlled by a magnetic head driver (Mag driver) 6 to generate a magnetic field, and together with the magnetic head driver 6 constitutes magnetic field generating means. As shown in FIG. 1, the magnetic field generating means generates a magnetic field (Magnetic Field) modulated according to the non-inverted section length limiting code when writing the recording data to the magneto-optical disk 9, as shown in FIG. 9 to the signal recording layer.

The optical block unit 1 also has an optical head 2 for irradiating a light beam focused on the signal recording layer of the magneto-optical disk 9 which is rotationally operated by the rotary operation mechanism 7. The optical head 2 includes a laser diode, which is a light source that serves as a light emitting means, and a condenser lens, which serves as a condensing means.

The emission wavelength λ of the laser diode is 690 nm, for example. The numerical aperture NA of the objective lens of the condenser lens is, for example, 0.55. In this case, the diameter of the beam spot formed by condensing the light flux in the optical head 2 is λ / NA = 0.69 (μ
From m) /0.55≈1.2 μm, it becomes about 1.2 μm.

The light emission of the laser diode of the optical head 2 is controlled by a laser driver (LD driver) 4. The optical head 2 constitutes a luminous flux irradiating means together with the laser driver 4. The luminous flux irradiating means irradiates a region of the signal recording layer of the magneto-optical disk 9 to which the modulating magnetic field is applied, with the luminous flux emitted from the laser diode being condensed by the condenser lens. At the time of writing the recording data to the magneto-optical disk 9, the area on the signal recording layer irradiated with the light beam condensed by the condenser lens is higher than the so-called Curie temperature of the material forming the signal recording layer. Be heated.

Further, the optical head 2 has a photodetector for receiving the light flux of the light flux applied to the magneto-optical disk 9 which is reflected by the signal recording layer of the magneto-optical disk 9.
This photodetector sends a photodetection current to an IV (current-voltage) converter 3.

The optical head 2 is driven by a biaxial actuator slider (2axis Slide) 5.
Biaxial directions of an optical axis direction (focusing direction) of the condenser lens and a direction (tracking direction) orthogonal to the optical axis and a recording track on the magneto-optical disk 9, and further,
The movement of the magneto-optical disk 9 is controlled in the radial direction.

The pre-pit signal (PRF) output from the IV converter 3, that is, the address area 2
The signal read by the gain controller (G.
C. ) 10 through a waveform shaper (Pulse det)
Waveform shaping is performed at 11. The waveform-shaped pre-pit signal (PRF) is a PLL (Phase Lock).
ed Loop) circuit 12, VCO (voltage controlled oscillator)
13 and an R / W (modulation (encoding) demodulation (decoding)) circuit 17 serving as a modulation means.

The above PLL circuit 12 and VCO circuit 13
Performs clock reproduction based on the pre-pit signal (PRF) and sends it to the control circuit (CPU) 14. R / above
The W circuit 17 performs address reproduction based on the prepit signal (PRF) and sends it to the control circuit 14.

The magneto-optical read signal (MO) output from the IV converter 3 is passed through a gain controller (GC) 15 and then a waveform shaper (Pulse d).
et) 16, and the waveform is shaped. The waveform-shaped magneto-optical read signal is sent to the R / W circuit 17. The R / W circuit 17 decodes the magneto-optical read signal and transfers it to the control circuit 14.

The R / W circuit 17 encodes the data transferred by the control circuit 14, and based on this data, a PPD (Programmable Ph).
control circuit 18 is controlled. This PPD
The circuit 18 includes the R / W circuit 17 and the control circuit 14.
Under the control of the magnetic head driver 6 and the laser driver 4 to write the recording data on the magneto-optical disk 9, the magnetic field generated by the magnetic head 8 and the laser diode of the optical head 2 emits light. Control the phase.

Further, the fapc signal output from the IV converter 3 is ALPC (laser output control (Aut).
o Laser Power Control
r)) is sent to the circuit 19. This ALPC circuit 19 is
Based on the fapc signal and the control by the control circuit 14, the light emission output of the laser diode corresponds to writing of recording data to the magneto-optical disk 9 or reading of recording data from the magneto-optical disk 9. Control to output.

Then, a focus error signal (focus error) output from the IV converter 3,
The pull-in signal (pull in) and the tracking error signal (trk error) are transmitted to the servo (Serv).
o) sent to the circuit 20. The servo circuit 20 controls the biaxial actuator slider 5 based on the error signals and the control of the control circuit 14 so that the light beam is focused by the optical head 2 on a predetermined recording track. To

The control circuit 14 communicates with the controller 21 via the controller 21 via SCSI (Small).
Computer System Interfac
e) Host (HOS) connected via bus (BUS)
T) Data transfer is performed with the circuit 22. The host circuit 22 receives an input signal from an operation unit (not shown), supplies a signal for instructing writing or reading of recording data to the control circuit 14 via the controller 21, and also to the magneto-optical disk 9. The recording data to be written is supplied. The controller 21 also encodes and decodes an error correction code (ECC).

In the magneto-optical recording device configured as described above, when the host circuit 22 gives an instruction to write the recording data to the magneto-optical disk 9, the controller 21 writes the recording data. The servo circuit 20 is controlled by designating the sector for performing the error correction, the error correction code is encoded with respect to the recorded data, and the encoded error correction code is transferred to the R / W circuit 17. Under the control of the controller 21, the servo circuit 20 moves the magnetic head 8 and the optical head 2 to a position corresponding to a designated sector.

The R / W circuit 17 controls the PPD circuit 18 in synchronization with the system clock to control the magnetic field generated by the magnetic head 8 and the phase of the light beam emitted by the laser diode. The recording data is written in the magneto-optical disk 9 by using the magnetic field and the light flux.

In this magneto-optical recording device, the above R /
The W circuit 17 modulates the recording data into the non-inverted section length limiting code (RLL code). In this magneto-optical recording device, the non-inverted section length limiting code is, for example, EF.
M (Eight to Fourteen Module)
modulation) and, as shown in FIG. 1, modified EFM (modified Eight to Fo).
This is a code generated by urteen modulation. In the non-inverted section length limiting code by the modified EFM modulation, the number of consecutive “0” s is 2 or more and 9 or less. That is, in this non-inverted section length limited code by the modified EFM modulation, 1 channel bit (channel) is T
Then, the minimum inversion interval (shortest mark length) is regulated to 3T, and the maximum inversion interval (longest mark length) is regulated to 10T. Therefore, in this magneto-optical recording device, the recording data is limited so that the minimum inversion interval spans a plurality of channel bits.

In the magneto-optical recording apparatus according to the present invention, the non-inversion section length limiting code may have a number of consecutive "0" s of 1 or more and a minimum inversion interval of 2T or more. . Even when the minimum inversion interval is 2T, this minimum inversion interval spans a plurality of channel bits.

In this magneto-optical recording apparatus, if the linear density of the recording data on the magneto-optical disk 9 is 0.4 (μm / bit), the 1-channel bit length is 0.2 (μm / bit). Channel bit length). The beam spot diameter by the optical head 2 is about 1.2.
Since it was μm, one channel bit length corresponds to about 1/6 of the beam spot diameter.

The laser diode is the PP
Controlled by the D circuit 18, pulse light emission is performed once for a plurality of channel bits. In this laser diode, the recording clock is 50 MHz, the pulse width of light emission is, for example, 10 nsec, and the peak of the optical output (pea).
k power) is about 15 mW.

As shown in FIG. 1, the pulse emission of the laser diode is from the front edge of the mark to be written on the recording track to the second channel bit, that is,
After two clocks, the magnetic field generated by the magnetic head 8 is the write saturation magnetic field (Write Field Threshold).
Light is emitted when a sufficiently strong magnetic field is directed upward or downward from d). On the recording track of the magneto-optical disk 9, after pulse emission of the laser diode, in a mark formation area (Mark Formation) which is a cooling process of the signal recording layer,
Written mark (Overwritten Mar
k Shape) is formed. Since the marks are written one after another in a state of being partially overlapped, only the front edge of each mark remains to indicate the recording data.

The pulse emission interval of the laser diode is 2 channel bits (2 clocks) when the mark length (reversal interval) is 2T or 4T or more (4T, 5T, 6T ...). That is, in this case, the laser diode has two channel bits (2
Flashes once per clock).

Further, when the mark length (reversal interval) is an odd number of channel bits (3T, 5T ...), the pulse emission interval of this laser diode is 2 channel bits (2 clocks) up to the edge after the mark. , And the last part of this mark has 3 channel bits (3 clocks). That is, in this case, the laser diode has three channel bits (3
Flashes once per clock).

That is, the interval until the next pulse emission is 2
If the pulsed light emission that is a channel bit is called P ₂ and the pulsed light emission that the interval until the next pulsed light emission is 3 channel bits is called P ₃ , the mark length (reversal interval) is 2nT (n = 1, 2, 3) mark is n × P ₂
(Pulse emission P ₂ is written n times). Similarly, the mark length (reversal interval) is (2n + 1).
The mark of T (n = 1, 2, 3 ...) is (n−1) ×
Writing is performed by P ₂ + P ₃ (pulse light emission P ₂ is (n−1) times and pulse light emission P ₃ is once).

The mark is formed on the recording track, that is, between the groove formed on the magneto-optical disk 9. The groove serves as a thermal barrier against adjacent recording tracks. The mark formed on this groove is
It does not affect the read signal when reading recorded data. Further, since the channel bit length is shorter than the beam spot diameter, a clean mark having a large radius of curvature of the edge of the mark is formed between the grooves.

In this magneto-optical recording apparatus, when the host circuit 22 gives an instruction to read the recording data from the magneto-optical disk 9, the controller 21 selects a sector for reading the recording data. The servo circuit 20 is designated and controlled. The servo circuit 2
Under the control of the controller 21, 0 operates to move the magnetic head 8 and the optical head 2 to a position corresponding to the designated sector.

The R / W circuit 17 binarizes the data read from the magneto-optical disk 9 and transfers it to the controller 21. The controller 21
Decodes the error correction code for the read recording data and transfers it to the host circuit 22.

[0053]

As described above, in the magneto-optical recording apparatus according to the present invention, since the light emission of the light emitting means of the optical head is pulse light emission once for a plurality of channel bits, the pulse light emission frequency is lowered. Therefore, the control of the light emitting means can be facilitated. Further, since the pulse emission frequency is low, the power consumption of the light emitting means can be reduced.

Further, regarding the modulation of the magnetic field, the frequency can be lowered and the magnetic field can be controlled by the container.

That is, the present invention adopts the CAV (constant angular velocity) rotation and the constant linear density of the recording data by using the zone system in the magneto-optical disk, while modulating the magnetic field in the magnetic head and the pulse emission in the optical head. Therefore, it is possible to provide a magneto-optical recording device in which data can be recorded favorably.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a state of a magneto-optical recording medium on which an information signal has been recorded in a magneto-optical recording device according to the present invention.

FIG. 2 is a plan view schematically showing the configuration of the magneto-optical recording medium.

FIG. 3 is a plan view schematically showing a structure of a sector in the magneto-optical recording medium.

FIG. 4 is a block diagram showing a configuration of the magneto-optical recording device.

[Explanation of symbols]

 2 optical head 4 laser driver (LD driver) 6 magnetic head driver (Mag driver) 8 magnetic head 9 magneto-optical disk 17 R / W circuit

Claims (1)

[Claims] 1. A modulation means for modulating recorded data into a non-inverted section length limiting code having a minimum inversion interval over a plurality of channel bits, and a modulation magnetic field according to the non-inverted section length limiting code. It has a magnetic field generating means for applying to the magnetic recording medium, a light emitting means and a condensing means, and condenses the luminous flux emitted by the light emitting means to the region of the magneto-optical recording medium to which the modulation magnetic field is applied. A light flux irradiating means for converging and irradiating the light by means for irradiating, and the light emitting means is adapted to perform pulsed light emission once for a plurality of channel bits.