JPH08153349A - Digital data recording method, digital data recorder and digital data recording/reproducing device - Google Patents

Abstract

PURPOSE: To improve data transfer speed by generating a recording basic clock synchronizing with a reference clock beforehand recorded on a magneto-optical recording medium and of the same frequency as the basic clock of the data to be recorded. CONSTITUTION: A PLL circuit 8 receives an RF signal (light intensity signal) SRF according to a clock pit formed on a magneto-optical disk 2 as a prepit by e.g. embossed work, etc., at a fixed interval beforehand, and generates the clock (called as basic clock and so on) SRF synchronizing with the clock pit and coinciding with the frequency of the basic clock of the signal to be recorded on the magneto-optical disk 2 to supply it to a multilevel digital phase modulation circuit 9. In such a case, by modulating laser light by a phase modulation signal DR1, and recording the data DR0 on the magneto-optical disk 2, the data are recorded by edge position modulation of an information pit with simple constitution and at high speed.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Fields of Industrial Application Conventional Technology (FIGS. 17 and 18) Problem to be Solved by the Invention Means for Solving the Problem Action Example (1) First Example (FIGS. 1 to 11) (2) Basic Format (FIGS. 12 and 13) (3) Second embodiment (FIG. 14) (4) Third embodiment (FIGS. 15 and 16) (5) Other embodiments Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital data recording method, a digital data recording device, and a digital data recording / reproducing device which can be applied to, for example, high density recording of desired data on a magneto-optical disk.

[0003]

2. Description of the Related Art Conventionally, as a recording / reproducing method for a magneto-optical disk device, an edge position for shifting the edge positions of the front end and / or the rear end of an information bit from a predetermined reference position in a step-like manner according to data to be recorded. A method for recording and reproducing data by modulation is proposed in Japanese Patent Application No. 5-126437.

According to this recording / reproducing method, changes in the length of the pit and the position of the pit edge can be detected with high accuracy, and information can be recorded and reproduced by a minute change which has been considered impossible until now. It is possible, and higher density recording than ever can be realized. FIG. 17 shows the principle of recording data on the magneto-optical disk by the edge position modulation.

First, PWM (Pulse
Width Modulation) Modulated recording signal (Fig. 17 (B))
Generate Then, an information pit (FIG. 17A) corresponding to the length at the time of the zero cross is formed. In this way, the position of the edge of the information bit changes from the position shown in the reference clock (FIG. 17 (C)) to a step shape. In accordance with this amount of change, for example, data of 8 levels from 0 to 7 (that is, 3 bits) can be recorded for one edge of the information bit.

As shown in FIG. 18, the principle of reproducing the data recorded in this way is to amplify the RF signal (FIG. 18A) reproduced from the magneto-optical disk and binarize the RF signal. (FIG. 18B) is obtained. Since a clock pit is formed on the magneto-optical disk on which data is recorded, a reference clock based on this is formed (FIG. 18C).
Is generated, and a sawtooth wave signal (FIG. 18D) is further generated in synchronization with this reference clock. Then, the position of the edge of the information bit is detected by detecting the value of the sawtooth wave signal at the timing when the sawtooth wave signal and the binarized RF signal cross each other, and the data thus recorded is reproduced. To do.

[0007]

By the way, in the above-mentioned magneto-optical disk device of the prior application, optical modulation recording is performed while applying an alternating magnetic field onto the magneto-optical disk. That is, in this magneto-optical disk device, first, a recording basic clock that is synchronized with a reference clock obtained by reproducing a clock pit of the magneto-optical disk is generated, and an alternating magnetic field having the same frequency as that of the recording basic clock is generated to generate the magneto-optical disk. Is applied to the recording position of. At the same time, the phase of the basic recording clock is changed according to the information to be recorded, and based on this basic recording clock, the recording position of the magneto-optical disk is irradiated with laser light for magneto-optical recording.

However, in such a magneto-optical disc device, an alternating magnetic field sufficient for recording is generated by modulating the external magnetic field generating coil, and the frequency for applying the required magnetic field is limited by the characteristics of the coil. Will be done. In the recording / reproducing method by the edge position modulation of the information bits as described above,
Further, in consideration of recording / reproduction at a high transfer rate, there is a problem that the restriction when the alternating magnetic field is generated by the external magnetic field generating coil becomes a factor that determines the transfer rate.

The present invention has been made in consideration of the above points, and when recording data by edge position modulation of an information bit, a digital data recording method and a digital data recording method capable of recording at a much higher speed with a simple structure. It is intended to propose a data recording device and a digital data recording / reproducing device.

[0010]

In order to solve such a problem, in the digital data recording method of the present invention, a basic clock of user data which is to be recorded in synchronization with a reference clock pre-recorded on an optical recording medium is provided. A recording basic clock having the same frequency is generated, and a recording signal in which the edge phase of the recording basic clock is slightly shifted according to user data to be recorded is generated. Then, a laser beam modulated by this recording signal is irradiated onto the magneto-optical recording medium to which a constant external magnetic field is applied to form a recording pit.

Further, in the digital data recording method of the present invention, a recording basic clock having the same frequency as the basic clock of the user data to be recorded is generated and recorded in synchronization with the reference clock previously recorded on the optical recording medium. A recording signal is generated by slightly shifting the edge phase of the basic recording clock according to the user data to be recorded. Then, the phase change recording medium is irradiated with laser light modulated by this recording signal to form a recording pit.

[0012]

With the constant external magnetic field applied to the magneto-optical recording medium, the data transfer rate is improved regardless of the frequency limit of the alternating magnetic field that can be generated by the external magnetic field generating coil. Can be made. In the case of a phase change recording medium, an external magnetic field need not be generated as compared with the case of recording data on a magneto-optical recording medium.
The configuration can be simplified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment In FIG. 1, reference numeral 1 generally indicates a magneto-optical disk device to which the magneto-optical recording method according to the present invention is applied. The magneto-optical disk 2 is rotationally driven by a spindle motor 4 controlled by a spindle servo circuit 3 so as to satisfy a specified rotational speed or linear velocity. Under the control of the laser power control circuit 6, the pick-up 5 irradiates the magneto-optical disk 2 with laser light, and irradiates an optical spot having a predetermined intensity necessary for magneto-optical recording or reproduction. Also pick-up 5
Detects the reflected light from the magneto-optical disk 2 and demodulates the detection signals SMO and SRF from the demodulation / decoding circuit 7 and PLL (Phase Lock).
edLoop) Output to the circuit 8.

During reproduction, the demodulation / decoding circuit 7 picks up the pickup 5.
The supplied signal (MO signal) SMO is demodulated and decoded, and output to an output signal processing circuit (not shown).
A PLL circuit 8 receives an RF signal (light intensity signal) SRF corresponding to a clock pit, which is formed in advance as a prepit on the magneto-optical disc 2 at a predetermined interval by, for example, embossing, synchronizes with the clock pit, and the magneto-optical disc. A clock that matches the frequency of the basic clock of the signal to be recorded on 2 (hereinafter referred to as the recording basic clock) C
LK is generated and supplied to the multilevel digital phase modulation circuit 9.

An external magnetic field generating coil 11 for applying an external magnetic field Hw to the magneto-optical disk 2 according to the control of the magnetic drive circuit 10 at the time of recording is arranged on an extension line of the laser beam emitted from the pickup 5. . Further, the pickup 5 is subjected to focus servo, tracking servo, and threaded servo under the control of the servo circuit 12.

The ECC addition modulation circuit 13 adds an error correction code to the data DIN supplied from an input signal processing circuit (not shown) and modulates the data DIN, and outputs it as recording data DR0 to the multi-level digital phase modulation circuit 9. To do. The multi-level digital phase modulation circuit 9 shifts the rising and falling edges of the basic recording clock CLK minutely in a step-like manner in accordance with the recording data DR0 to perform multi-level digital phase modulation to generate a phase modulation signal DR1. For example, if data of 8 levels from 0 to 7 is recorded for one edge of the information bit (that is, data of 3 bits for one edge), the recording data DR0 is divided into units of 3 bits, and the 3
The rising and falling edges of the basic clock CLK are phase-modulated corresponding to the bit.

For example, in the case of recording a data string of 00010110101 ... If it is divided into units of 3 bits, 000,
010, 110, 101 ... Therefore, the rising edge of the first basic clock CLK is not phase modulated,
The trailing edge is phase-modulated so as to be offset by two reference shift amounts. This is because 000 = 0 and 010 = 2.

Further, the next rising edge of the basic clock CLK is phase-modulated so as to be shifted by 6 reference shift amounts,
The trailing edge is phase-modulated so as to be offset by five reference shift amounts. This is because 110 = 6 and 101 = 5. The reference shift amount Δ is Δ = 0.005 [μm] as shown in FIG. This phase modulation signal DR1
A laser emission recording signal DR2 is generated from this and is supplied to the laser power control circuit 6.

In the above structure, when recording data, the magneto-optical disk device 1 first performs an erasing operation by the external magnetic field generating coil 11 in order to align the magnetization directions of the perpendicular magnetic films on the magneto-optical disk 2. External magnetic field H
While applying w in a fixed direction, laser light is emitted from the pick-up 5 controlled by the servo circuit 12 to a predetermined position. Next, the external magnetic field generation coil 11 for recording is used to reverse the external magnetic field Hw, and the laser power control circuit 6 operates in accordance with the laser emission recording signal DR2 output from the laser emission recording signal generation circuit 14 to change the recording area to the recording area. Information is written in the magneto-optical disk 2 by irradiating laser light.

With respect to this recording principle, FIG. 2 shows an example in which the recording basic clock CLK is modulated into four values by the multilevel digital phase modulation circuit 9. First, the basic recording clock CLK (Fig. 2
(A) is a multi-valued digital phase modulation circuit 9 in which the edge of the basic clock is slightly changed according to the data to be recorded.
And is supplied to the laser emission recording signal generation circuit 14 as a phase modulation signal (FIG. 2B). A laser emission recording signal (FIG. 2C) is generated in the laser emission recording signal generation circuit 14, and this is supplied to the laser power control circuit 6.

An external magnetic field Hw (see FIG. 2) in the magnetic field direction for recording is applied to the magneto-optical disk 2 magnetized in the direction (direction x) opposite to the direction of the magnetic field to be recorded in advance (direction ◎, for example).
While applying (D)), the laser light modulated by the control of the laser power control circuit 6 is irradiated based on the laser emission recording signal to record the data. Figure 2 (D)
In FIG. 5, it is assumed that the sign “+” magnetizes the magneto-optical disk 2 in the ⊚ direction and the sign “−” magnetizes the magneto-optical disk 2 in the x direction. The external magnetic field Hw is the strength of the magnetic field that allows the perpendicularly magnetized film of the magneto-optical disk 2 to be sufficiently magnetized, and the recording laser power is necessary for the temperature of the magnetized film to sufficiently exceed the Curie temperature in FIG. 2C. Use as power.

Illumination positions t = t0, t1, t2, t3 and t0 ', t of all the laser light pulses that can be actually generated.
When the information pits formed at 1 ', t2', and t3 'are overlapped and written, as shown in FIG. 2 (E), the data is written at the boundary where the magnetization direction is reversed, that is, the edge position modulation of the information pits. Can be recorded. 2 that the position of the rear end of the formed pit (FIG. 2 (E)) and the position of ending the laser irradiation (t3 'in FIG. 2 (C)) are deviated. This is because the influence of laser heat diffusion is taken into consideration. That is, if the laser is irradiated in correspondence with the position of the rear end of the pit, there is a time for the heat to diffuse, and the mark becomes larger than the size of the pit to be recorded.

Now, let us consider how much laser should be applied to the pit to be recorded. When writing a mark on a magneto-optical disk, an experiment was carried out under the conditions described below to find out what duty ratio was suitable for writing, and the results are shown in FIGS. Figure 3 shows the marks to be recorded and the DU
It shows the relationship with the TY ratio. In this experiment, for the sake of simplicity, the linear velocity of the disk was set to about 5.5 [m], and 312 [n
The relationship between the laser irradiation time and the recording pits was examined by writing a mark with a constant period with the period [s] as one period. Two types of writing laser power Pw were tested, that is, 12 [mW] and 16 [mW].

As shown in FIG. 3, the duty ratio means the ratio of the laser emission time when the one cycle time of 312 [ns] is 100%. Therefore, the recorded pit is DUTY.
The ratio is 50 [%], which corresponds to about 156 [ns], and the duty ratio 10
[%] Corresponds to about 31 [ns]. Now, FIGS. 4 and 5
Is the duty when the writing laser power Pw = 12 [mW]
The figure shows the state of a reproduction RF signal when data is recorded while changing the ratio from 10% to 50%. The recording direction is
This is the direction in which the amplitude increases in the figure.

In the case of FIG. 4A (that is, the duty ratio is 10)
In the case of [%]), the amplitude of the waveform has not risen yet, but in the cases of FIG. 4 (B) and FIG. 4 (C) (that is, DU
When the TY ratio is 20 [%] and 30 [%]), an appropriate amplitude appears. However, in the case of FIGS. 5D and 5E (that is, when the duty ratio is 40 [%], 50 [%]), the recorded mark is too long, so that the amplitude is shown in FIG. 4 (B) and FIG. It is smaller than that of (C).

FIGS. 6 and 7 show the waveform spectra of FIGS. 4 and 5. As can be seen from FIGS. 6 and 7, the carrier level (S / N ratio) is highest when the duty ratio is 20% and 30%. The S / N ratio is 41
Considering that more than dB is desired, in this example, DUTY
It can be said that the mark was most clearly written on the disk when the ratio was 20% to 30%.

On the other hand, in FIGS. 8 and 9, when the writing laser power Pw = 16 [mW], the duty ratio is from 10 [%] to
Reproduction RF when recording data by changing to 40%
The state of the signal is shown. For reference, DUTY is shown in Figure 9.
The experimental data when the ratio is 100% is also shown. FIG.
Also, in the example of FIG. 9, since the recording power becomes higher, the duty ratio at which the optimum mark can be recorded is 10% to 20%. 10 and 11 show the waveform spectra of FIGS. 8 and 9. From the same consideration as in FIGS. 6 and 7, it can be said that the mark was most clearly written on the disk when the duty ratio was 10% to 20%.

In this magneto-optical recording, the information pits are formed by the heat generated by the laser light, so that it is not always necessary to continuously emit the recording laser pulse. Since the laser irradiation pulse may be applied so that the formed information pit has a shape as shown in FIG. 2 (E), the shape of the light emission pulse in FIG. 2 (C) is, for example, the pit from t0 to t3 ′. When it is desired to form, a plurality of minute pulses may be continuously irradiated as shown in FIG.

According to the above construction, the recording basic clock CLK which is synchronized with the reference clock pitch previously recorded in the magneto-optical disk 2 and which has the same frequency as the basic clock of the data DR0 to be recorded is generated and recorded. A phase modulation signal DR1 is generated by slightly shifting the phase of the recording basic clock CLK according to the data DR0, the laser light is modulated by the phase modulation signal DR1, and the data DR0 is recorded on the magneto-optical disk 2. As a result, when data is recorded by the edge position modulation of the information bit, the data can be recorded at high speed with a simple structure.

Further, according to the above-mentioned structure, the information pits can be modulated by writing at high speed for writing by optical modulation, and the double-sided magneto-optical disk capable of recording on both sides can be used for writing by optical modulation. In the above-mentioned embodiment, the case where the external magnetic field Hw generated by the external magnetic field generating coil 11 controlled by the magnet drive circuit 10 is applied to the magneto-optical disk 2 has been described. Instead of the generating coil 11, a magnet may be applied. In this case, when erasing and recording,
If the magnetic field applied to the magneto-optical disk 2 is reversed, the same effect as that of the above-described embodiment can be realized.

(2) Structure of Recording Format Next, FIG. 12 shows an example of a basic format of a magneto-optical disk to which the recording method of the present invention is applied. Here, the pits are formed by partially reversing the magnetization of the magneto-optical film. A pit train is recorded on the magneto-optical disk 2 having a diameter of 120 mm in the CLV mode with a track pitch of 1.6 μm. All information has a fixed period of 1.67 (μ
It is recorded as eight-step shift amounts of the edge positions of the front end (rising edge) and the rear end (falling edge) of the pits arranged every m]. The unit shift amount Δ, which is one unit of this shift amount, is set to 0.05 [μm].

Since the information of 3 bits can be recorded in each of the 8 steps of the shift amount of the edge position of each pit thus arranged, the linear recording information density in the pit row direction is 0.28 [μm / bit]. ], Which is more than double the current CD system. In the CD system, even when the linear velocity is set to the upper limit of 1.2 [m / s], the EFM
(Eight to Fourteen Modulation) By modulation, 8 bits of data bits to be recorded are 14 bits of information bit and 3 bits of margin bit, total 1 bit.
Since this is converted into a 7-bit channel bit and recorded in the pit on the disk, the linear recording information density is about 0.6 [μm / bit] in consideration of this EFM modulation.
That is, since the shortest bit of about 0.9 [μm] corresponds to a channel bit for 3 bits, (0.9 ÷ 3) × (17 /
8) = about 0.6 [μm / bit].

Here, as shown in FIG. 13, the edge position of the pit recorded on the magneto-optical disc 2 is shifted stepwise from the reference position at the center of the pit according to the digital information to be recorded. Is the shift period Ts
(= Δ × 7) is a transient period of the MO signal (differential detection signal) that is determined according to the transfer characteristics of the differential optical detection system of the pickup 4 (a period other than the steady state in which the level is 0 or the saturation level). It is set within a range corresponding to a period shorter than the rising period tr or the falling period tf.

The MO signal is output from the RF circuit 31 which processes the detection signal of the pickup 5 of the reproducing apparatus, which will be described later, and the transition period is determined by the transfer characteristic of the pickup 5. Generally, the transfer characteristic of an optical system is
Its transfer function (OTF)
Is the absolute value of MTF (Modulation Transfer Functio
n), this MTF is defined as the numerical aperture N of the lens.
It depends on A and the wavelength λ of the laser.

Within the shift period Ts, the unit shift amount Δ
Is shifted by a unit amount smaller than 0.05 [μm], the recording density can be further increased. By performing A / D conversion of the MO signal at the timing of the rising edge of the sample clock SP which is phase-synchronized with the reference position at the center of the recorded pits, the shift amount of the pit edge position is 0. Playback level L0 corresponding to ~ 7
~ L7 can be obtained. As described above, the condition that the reproduction levels L0 to L7 can be detected at one sample timing in the transition period of the MO signal is that the shift period Ts ≦ transition period (rise period tr or fall period tf).

Here, as the sampling timing by the sample clock SP, the timing corresponding to the center of the shift period Ts is desirable, and with this timing, the reproduction level is detected over the entire range of the transient period of the MO signal. It becomes possible. Returning to FIG. 12 again,
In the magneto-optical film of the magneto-optical disk 2, a servo area composed of five servo pits P1 to P5 is inserted between data areas where 44 data pits corresponding to data to be recorded are recorded. There is. The five servo pits P1 to P5 are thermomagnetic recording by a recording method of irradiating the spot S having a predetermined intensity for each half cycle of the alternating magnetic field described above in the formatting process for the magneto-optical disc 2, that is, the initialization process. Thus, recording is performed on the magneto-optical film.

Separately from this, the clock pit CP is previously formed as a prepit in each servo area by embossing or the like. The clock pit CP is formed with extremely high positional accuracy in the manufacturing process of the magneto-optical disc 2. Five pits P1 to P1 recorded in this servo area
Two of the P5 are the education pits P1 and P2, and the remaining three are the reference pits P3 to P5. The left edge of the educational pit P2 in the figure is set to any one of eight shift positions 0 to 7, and the right edge of the right edge in the figure is also 0 to 7. Is set to any one of the eight shift positions.

The position M of the front edge and the position N of the rear edge of the education pit P2 are regularly set so as to be different in each servo area. That is, M and N are set to (0, 0) in the first servo area, and in the next servo area,
It is set to (0, 1). Similarly, (0, 2), (0,
3), ..., (7,6), (7,7) are regularly combined. As a result, all possible combinations of positions of the front edge and the rear edge of the teaching pit P2 are prepared in 64 (= 8 × 8) servo areas.

The education pit P1 is a dummy in this case. That is, it is theoretically possible to form the educational data not on the edges of the pit P2 but on the edges of the pit P1. However, if you do so,
Since the pit adjacent to the left of the pit P1 is the data pit of the data area, the position of the edge changes corresponding to the data. As a result, the degree of interference of the education pit P1, especially with respect to the edge on the data area side, changes depending on the data.

Therefore, it becomes difficult to pattern the educational data in a constant state as described later. Therefore, as in the embodiment, it is preferable to form the educational data not at the edges of the pit P1 but at the edges of the education pit P2. In this way, the reference pit P3 adjacent to the trailing edge of the education pit P2 is
Then, since the educational pit P1 adjacent to the front edge is both constant (it does not change) with the edge being (0,0), when the educational data of the educational pit P2 is read, a constant intersymbol interference is always present. , A constant pattern can be obtained.

The reference pits P3 to P5 are pits for obtaining the data of the reference positions (0,0) and (7,7). This reference position data is also theoretically, for example, pit P.
It is also possible to form the edges at both ends of 5. However, in that case, as in the case of the education pit, the proportion of interference from the adjacent data area changes depending on the recorded data, so that the right side of the reference pit P5 in the figure as in the embodiment. It is preferable not to form reference position data on the trailing edge.

(3) Second Embodiment FIG. 14 is a block diagram showing the structure of the magneto-optical recording / reproducing apparatus of the present invention. The magneto-optical disk 2 is rotated by a spindle motor 4. Information is recorded on the magneto-optical disk 2 by the recording format shown in FIG. That is, digital information is recorded by shifting at least one of the front edge and the rear edge of the information pit from a predetermined reference position in a step-like manner. And, in this magneto-optical disk 2,
A servo area is formed at a constant cycle, and educational pits P1 and P2 and reference pits P3 to P5 are formed.
Naturally, the data pits are formed in the data area.

The pickup 5 irradiates the magneto-optical disc 2 with a laser beam and reproduces the signal recorded in the magneto-optical disc 2 from the reflected light. The detection signal of the pickup 5 is processed by the RF circuit 21, and the magneto-optical disc 2 is processed.
Is separated into an RF signal corresponding to a change in the amount of reflected light of the laser light applied to the optical disk and an MO signal corresponding to the direction of the Kerr rotation angle of the reflected light of the laser light applied to the magneto-optical disk 2. Is output.

Incidentally, the pick-up 5 is composed of, for example, a laser light source such as a laser diode, a collimator lens, an objective lens, a polarized beam splitter, an optical component such as a cylindrical lens, and a photodetector divided into a predetermined pattern. The target track of the magneto-optical disk 2 is irradiated with laser light, and the reflected light outputs a detection signal corresponding to the P-polarized component and the S-polarized component.

The RF circuit 21 differentially amplifies the detection signal of the P-polarized component and the detection signal of the S-polarized component, so that the laser light is generated in the magneto-optical film (perpendicular magnetization film) of the magneto-optical disk 1. The rotation of the received polarization plane, that is, the Kerr rotation angle is detected, and a signal corresponding to this Kerr rotation angle is output as an MO signal. At the same time, the sum of the detection signal of the P-polarized component and the detection signal of the S-polarized component is amplified, so that the amount of reflected light based on the diffraction phenomenon received by the laser light on the reflecting surface of the magneto-optical disc 1 is strong or weak. Is detected, and a signal corresponding to this reflected light amount is output as an FR signal.

The RF signal output from the RF circuit 21 is supplied to the focusing tracking servo circuit 22, the APC circuit 23 and the PLL circuit 24. The focusing tracking servo circuit 22 generates a focusing error signal and a tracking error signal from the input signal, and executes focusing control and tracking control in response to the error signal. Further, the APC circuit 23 applies servo so that the power of the laser light applied to the magneto-optical disc 2 becomes constant.

The PLL circuit 24 extracts a clock component from the RF signal corresponding to the clock pit CP supplied from the RF circuit 21, generates a sample clock SP having a predetermined phase relationship and other clocks, and performs A / D conversion. Circuit 2
5, supplied to the bias removal circuit 26 and the two-dimensional decoder 27. PLL used in normal CD system
The circuit performs clock reproduction using all RF signals, but in the case of the present embodiment, the magneto-optical disc 2 is provided with, for example,
Clock reproduction is performed using only the RF signal corresponding to the clock pit CP formed as a prepit by embossing or the like. As a result, stable clock reproduction can be performed without being affected by the data pits recorded on the magneto-optical film.

The spindle servo circuit 3 also controls the spindle motor 4 so that the magneto-optical disk 2 rotates at a constant angular velocity. On the other hand, the MO signal output from the RF circuit 21 is input to the A / D conversion circuit 25, and is converted into digital data (reproduction level) indicating 256 levels of 8 bits at the timing of the rising edge of the sample clock SP. D converted. The 8-bit data is supplied to the bias removing circuit 26, the bias component is removed by the bias removing circuit 26, and then the data is supplied to the two-dimensional decoder 27 and the controller 31.

The controller 31 is a CP for performing various calculations.
U and a program ROM in which a program executed by this CPU is stored. The data reproduced from the education pits P1 and P2 is converted into a two-dimensional decoder 2
A process such as mapping to 7 is executed. The two-dimensional decoder 27 decodes the signal supplied from the bias removal circuit 26 and supplies the output to the 6 → 8 bit conversion circuit 28. The 6-to-8-bit conversion circuit 28 stores four sets of input 6-bit data, converts them into three sets of 8-bit data, and outputs them to the error correction circuit 29.

The error correction circuit 29 corrects an error in the input data and then outputs it to the D / A conversion circuit 30. D
The / A conversion circuit 30 converts the input data into an analog signal and outputs it to an analog amplifier (not shown). The detailed operations of the bias removing circuit 26, the two-dimensional decoder 27, etc. are described in Japanese Patent Application No. 5-2087 filed by the applicant earlier.
The detailed description is given in No. 6 (JP-A-6-76303), and the description thereof is omitted.

(4) Third Embodiment Next, a case where the recording method according to the present invention is applied to a phase change type optical disk will be described. FIG. 15 shows a phase change type optical disk device. The parts corresponding to those in FIG. 1 are designated by the same reference numerals. The phase change type optical disc 41 is
The embossed pit train is recorded in advance at regular intervals, and is driven by the spindle servo circuit 3 so as to satisfy a prescribed rotation speed or linear velocity.

The PLL circuit 8 synchronizes with the embossed pits of the optical disc 41 from the RF signal SRF obtained from the embossed pit train, and matches the frequency of the basic clock of the signal to be recorded on the optical disc 41 from now on. A clock (hereinafter referred to as a recording basic clock) CLK is generated and supplied to the multi-level digital phase modulation circuit 9.

At the time of recording, the recording signal generating circuit 22 generates a laser emission recording signal DR2 according to the phase modulation signal DR1 output from the multi-level digital phase modulation circuit 9, and the laser is generated based on this signal. The power control circuit 6 irradiates the recording area with laser light to write information on the optical disk 41. As a principle of recording data, the multilevel digital phase modulation circuit 9 is used as in the case of the above-mentioned magneto-optical disk.
16 shows an example in which the basic recording clock CLK is modulated into four values with.
Is shown in.

Recording basic clock CLK (FIG. 16 (A))
Is modulated by the multi-valued digital phase modulation circuit 9 that slightly changes the edge of the basic clock according to the data to be recorded, and is input to the recording signal generation circuit 14 as the phase modulation signal DR1 (FIG. 16 (B)). . In the recording signal generation circuit 14, the optical disc 41 is generated based on the phase modulation signal DR1.
An actual laser emission recording signal DR2 (FIG. 16C) is generated so as to form a desired mark on the optical disc 41, and the optical disc 41 is irradiated with the laser beam by the laser emission recording signal DR2.
Record the data.

Now, when the laser light of high laser power PH shown in FIG. 16C is radiated on the optical disk 41,
The medium temperature of the irradiated portion rises to a molten state and becomes amorphous in the process of cooling. When a laser beam with a low laser power PL is irradiated, the irradiated portion becomes a crystallized state and becomes a crystal in the process of cooling.
These can be overwritten because they do not depend on the marks previously written on the optical disc 41.

Lighting positions t = t0, t1, t2, t3 and t0 ', t of the pulses of all the laser beams that can actually emit light.
When the marks formed at 1 ', t2', and t3 'are overlapped and written, as shown in FIG. 16D, the reference position of the mark (edge of the mark) at the boundary where the state change of the optical disk 41 occurs (edge of mark). Modulated digital data can be recorded by applying a small stepwise displacement from the edge of the position reference pit to the edge of the recording mark.

Incidentally, from FIG. 16, there is a deviation between the position of the rear end of the formed pit (FIG. 16D) and the position where the laser irradiation is ended (t3 'in FIG. 16C). I understand. This is because the influence of laser heat diffusion is taken into consideration. That is, if the laser is irradiated in correspondence with the position of the rear end of the pit, there is a time for the heat to diffuse, and the mark becomes larger than the size of the pit to be recorded. The amount of laser irradiation to the pit to be recorded is the same as in the case of the above-mentioned magneto-optical disk, and therefore its explanation is omitted here.

FIG. 16 (E) shows another example of the recording signal for laser emission (FIG. 16 (C)). FIG.
In 6 (E), after the laser is emitted with the PH power, it is lowered to the Poff power for a predetermined time to prevent heat accumulation and form a desired pit. further,
Also in the case of the phase change type optical disk, PH power and PL power may be emitted by a plurality of pulse trains as in the case of FIG.

According to the above configuration, in the case of the phase-change type optical disc 41, overwriting can be performed only by modulating the laser light without using an external magnetic field, so that an external magnetic field is unnecessary as compared with the case of the spectroscopic magnetic disc. In addition, the optical system can be simplified, and an optical disk device that can be made lighter, thinner, and less expensive can be realized.

(5) Other Embodiments In the above-mentioned embodiments, the case where the clock information is pre-recorded on the magneto-optical disk 2 or the phase change type optical disk 41 by a preplet such as an embossed disk has been described. Not only clock information but also tracking information and position information such as sector, address, absolute time, etc. may be formed by embossed pits. Further, the recording is not limited to the embossing, and the recording may be performed in advance on the magneto-optical disk by the pre-groove.

Further, in the above-mentioned embodiment, the magnetization direction of the perpendicularly magnetized film on the magneto-optical disk 2 is oriented in a fixed direction by the erasing process prior to the magneto-optical recording. When a multi-layer type magneto-optical disk capable of overwriting is used as the medium, the erasing process is not necessary, and the recording operation can be simplified accordingly and overwriting can be easily performed.

Further, in the above-described embodiment, the present invention is applied to a disk-shaped recording medium composed of a magneto-optical disk or a phase-change type optical disk by shifting the edge position of the recording basic clock in a step-like manner according to the recording data and performing optical modulation. Although the case of recording is described, the shape of the recording medium is not limited to this, and is suitable for wide application to optical recording methods and optical recording devices for various optical recording media such as card-shaped or tape-shaped recording media. .

[0064]

As described above, according to the present invention, the recording basic clock which is synchronized with the reference clock pre-recorded on the optical recording medium and has the same frequency as the basic clock of the data to be recorded is generated and recorded. The recording signal is generated by slightly shifting the phase of the recording basic clock according to the data to be used, and the laser light is modulated by the recording signal to record the data on the optical recording medium. Data recording method, digital data recording apparatus, and digital data recording / reproducing apparatus capable of performing high-speed recording with a simple structure when optical recording is performed by shifting the position of the position corresponding to the recording information from a predetermined reference position in a stepwise manner. Can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a magneto-optical disk device according to a digital data recording method and device of the present invention.

FIG. 2 is a timing chart for explaining a recording operation of the magneto-optical disk device of FIG.

FIG. 3 is a diagram showing a relationship between a recorded mark and a duty ratio.

FIG. 4 is a diagram showing a reproduction signal obtained when the duty ratio is changed from 10% to 30% when the laser power Pw = 12 [mW].

FIG. 5 is a diagram showing a reproduction signal obtained when the duty ratio is changed from 40 [%] to 50 [%] when the laser power Pw = 12 [mW].

6 is a diagram showing the waveform spectrum of FIG. 4;

FIG. 7 is a diagram showing the waveform spectrum of FIG. 5;

FIG. 8 is a diagram showing a reproduction signal obtained when the duty ratio is changed from 10% to 30% when the laser power Pw = 16 [mW].

FIG. 9 is a diagram showing a reproduction signal obtained when the duty ratio is changed to 40% when the laser power Pw = 16 [mW].

FIG. 10: DUTY when laser power Pw = 16 [mW]
It is a figure which shows the waveform spectrum when changing a ratio from 10 [%] to 20 [%].

FIG. 11: DUTY when laser power Pw = 16 [mW]
It is a figure which shows a waveform spectrum when changing a ratio from 30 [%] to 40 [%].

FIG. 12 is a diagram showing an example of a basic format of a magneto-optical disk to which the recording method of the invention is applied.

FIG. 13 is a diagram showing an edge position of a recording pit recorded on a magneto-optical disk.

FIG. 14 is a block diagram showing the configuration of a magneto-optical recording / reproducing apparatus of the present invention.

FIG. 15 is a block diagram showing a phase change type optical disc device according to the digital data recording method and device of the present invention.

16 is a timing chart for explaining a recording operation of the phase change type optical disc device of FIG.

FIG. 17 is a timing chart for explaining a high-density recording method by edge position modulation used in a conventional magneto-optical disk.

FIG. 18 is a timing chart for explaining a reproducing method of the magneto-optical disk recorded by the high density recording method of FIG.

[Explanation of symbols]

1 ... Magneto-optical disk device, 2 ... Magneto-optical disk, 3
...... Spindle servo circuit, 4 …… Spindle motor,
5 ... Pickup, 6 ... Laser power control circuit, 7 ... Demodulation / decoding circuit, 8 ... PLL circuit, 9 ...
Multi-valued digital phase modulation circuit, 10 ... Magnet drive circuit, 11 ... External magnetic field generating coil, 12 ... Servo circuit, 13 ... ECC addition modulation circuit, 14 ... Recording signal generation circuit, 21 ... RF circuit, 22 ... Forking tracking servo circuit, 23 ... APC circuit, 2
4 ... PLL circuit, 25 ... A / D conversion circuit, 26 ...
Bias removal circuit, 27 ... Two-dimensional decoder, 28 ...
6 → 8 bit conversion circuit, 29 ... Error correction circuit, 30 ...
... D / A conversion circuit, 31 ... Controller, 40 ... Optical disk device, 41 ... Optical disk.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G11B 20/10 351 Z 9463-5D

Claims (18)

[Claims] 1. A step for generating a recording basic clock having the same frequency as the basic clock of the user data to be recorded, in synchronization with the reference clock pitch previously recorded on the magneto-optical recording medium, and the user data to be recorded is predetermined. It is divided into units, and a step of generating a modulation signal corresponding to the recording pit by slightly shifting the phase of the edge of the recording basic clock by an amount corresponding to the information held by the predetermined unit, and a recording signal synchronized with the modulation signal. That is, the step of generating a recording signal for controlling the irradiation of the laser beam, the step of applying a constant external magnetic field to the magneto-optical recording medium in the recording direction, and the step of applying the external magnetic field to the magneto-optical recording medium. With the
A step of recording the user data on the magneto-optical recording medium by irradiating the magneto-optical recording medium with a laser beam modulated according to the recording signal to form recording pits. 2. The recording pit comprises a bias pit portion having a constant length and a modulation pit portion added to the front end and the rear end of the bias pit portion, and between the centers of the bias pit portions of each recording pit. The distances are set to have equal lengths.
Digital data recording method described in. 3. The digital data recording according to claim 1, wherein in the step of generating the recording signal, the recording signal is generated so as to have a pulse width which is shorter in time than the modulation signal. Method. 4. The digital data recording method according to claim 3, wherein the pulse width of the recording signal is about 1/5 or more and about 3/5 or less of the pulse width of the modulation signal. 5. The pulse width of the recording signal is about 2/5 or more and about 3/5 or less of the pulse width of the modulation signal when the power of the laser beam is 12 W. Digital data recording method described in. 6. The pulse width of the recording signal is about 1/5 or more and about 2/5 or less of the pulse width of the modulation signal when the power of the laser beam is 16 W. Digital data recording method described in. 7. The magneto-optical recording medium comprises a servo area in which control data used for recording user data is recorded in advance, and a data area in which the user data is recorded. The method for recording digital data according to item 1. 8. A plurality of education pits indicating all combinations that the leading edge and the trailing edge of the recording pit may have are previously recorded in the servo area. 7. The digital data recording method described in 7. 9. A means for generating a recording basic clock having the same frequency as the basic clock of the user data data to be recorded, in synchronization with the reference clock pitch previously recorded on the magneto-optical recording medium, and the user data to be recorded. Means for generating a modulation signal corresponding to the recording pit by minutely shifting the phase of the edge of the recording basic clock by an amount corresponding to the information held by the predetermined unit, and a recording signal synchronized with the modulation signal The means for generating a recording signal for controlling the irradiation of the laser beam, the means for applying a constant external magnetic field to the magneto-optical recording medium in the recording direction, and the external magnetic field for the magneto-optical recording medium. With the voltage applied,
A digital data recording apparatus comprising means for recording the user data on the magneto-optical recording medium by irradiating the magneto-optical recording medium with laser light modulated according to the recording signal to form recording pits. 10. A step for generating a recording basic clock having the same frequency as the basic clock of the user data to be recorded, in synchronization with the reference clock pitch previously recorded on the phase change type optical recording medium, and the user data to be recorded. Is divided into predetermined units, the phase of the edge of the recording basic clock is slightly shifted by an amount corresponding to the information held by the predetermined unit, and a step of generating a modulation signal corresponding to the recording pit, and recording synchronized with the modulation signal are performed. A step of generating a recording signal for controlling the irradiation of the laser beam, which is a signal, and irradiating the phase-change optical recording medium with the laser beam modulated according to the recording signal to form a recording pit. Accordingly, the step of recording the user data on the phase-change optical recording medium, the digital data recording method. 11. The recording pit comprises a bias pit portion having a constant length and modulation pit portions added to the front end and the rear end of the bias pit portion, and the distance between the centers of the bias pit portions of each recording pit is 11. The digital data recording method according to claim 10, wherein they are equal. 12. The digital data recording according to claim 10, wherein in the step of generating the recording signal, the recording signal is generated so as to have a pulse width which is shorter in time than the modulation signal. Method. 13. The digital data recording method according to claim 12, wherein the pulse width of the recording signal is about 1/5 or more and about 3/5 or less of the pulse width of the modulation signal. 14. The magneto-optical recording medium comprises a servo area in which control data used for recording user data is recorded in advance and a data area in which the user data is recorded. Item 10. The digital data recording method according to Item 10. 15. The servo area is prerecorded with a plurality of educational pits indicating all combinations that the leading edge and the trailing edge of the recording pit may have. Digital data recording method described in. 16. A means for generating a recording basic clock having the same frequency as a basic clock of user data data to be recorded, in synchronization with a reference clock pitch previously recorded on a phase change type optical recording medium, and the user to be recorded. Data is divided into predetermined units, means for generating a modulation signal corresponding to the recording pit by slightly shifting the phase of the edge of the recording basic clock by an amount corresponding to the information held by the predetermined unit, and a means for synchronizing with the modulation signal. A recording signal, a means for generating a recording signal for controlling the irradiation of the laser beam, and a laser beam modulated according to the recording signal is irradiated to the phase change optical recording medium to form a recording pit. A digital data recording device comprising means for recording the user data on the phase change optical recording medium by doing so. 17. A means for generating a recording basic clock having the same frequency as the basic clock of the user data data to be recorded, in synchronization with the reference clock pitch previously recorded on the magneto-optical recording medium, and the user data to be recorded. Means for generating a modulation signal corresponding to the recording pit by minutely shifting the phase of the edge of the recording basic clock by an amount corresponding to the information held by the predetermined unit, and a recording signal synchronized with the modulation signal The means for generating a recording signal for controlling the irradiation of the laser beam, the means for applying a constant external magnetic field to the magneto-optical recording medium in the recording direction, and the external magnetic field for the magneto-optical recording medium. With the voltage applied,
A unit for irradiating the magneto-optical recording medium with a laser beam modulated according to the recording signal to form a recording pit for recording the user data on the magneto-optical recording medium, and the unit for recording the user data. Means for reading data from the magneto-optical recording medium and generating a reproduction signal, means for detecting the phase shift amount in the edge portion of the recording pit from the reproduction signal, and decoding the user data from the phase shift amount A digital data recording / reproducing apparatus comprising: 18. A means for generating a recording basic clock having the same frequency as a basic clock of user data data to be recorded, in synchronization with a reference clock pitch previously recorded on a phase change type optical recording medium, and the user to be recorded. Data is divided into predetermined units, means for generating a modulation signal corresponding to the recording pit by slightly shifting the phase of the edge of the recording basic clock by an amount corresponding to the information held by the predetermined unit, and a means for synchronizing with the modulation signal. A recording signal, a means for generating a recording signal for controlling the irradiation of the laser beam, and a laser beam modulated according to the recording signal is irradiated to the phase change optical recording medium to form a recording pit. By doing so, means for recording the user data in the phase change optical recording medium, and reading data from the magneto-optical recording medium in which the user data is recorded Digital data consisting of means for outputting and reproducing signals, means for detecting the amount of phase shift in the edge portion of the recording pit from the reproduced signal, and means for decoding the user data from the amount of phase shift Recording / playback device.