JPH1116224A - Magnetic head drive - Google Patents

Abstract

(57) [Summary] A resonance field modulation method is adopted, and a resonance frequency of a resonance circuit is made variable according to a clock frequency of variable recording data. Further, the resonance frequency of the variably set resonance circuit can be synchronized with the clock with high accuracy. SOLUTION: A phase comparator 1 detects a phase error between a clock CK2 and an oscillation signal of a variable oscillation circuit 4, and obtains a DC control signal iDC obtained based on this detection information.
The resonance frequency of the variable oscillation circuit 4 is variably controlled by varying the inductance of the resonance circuit. Thereby, the magnetic head 1
2 is variably controlled so as to be always synchronized with the clock CK2. This is because the alternating magnetic field is always synchronized with the clock of the recording data which is variable for each zone. Can be regarded as having been obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic head for driving a magnetic head for applying a magnetic field to a recording medium in a data recording apparatus for recording data on a disk-shaped recording medium by, for example, a magnetic field modulation method. The present invention relates to a driving device.

[0002]

2. Description of the Related Art For example, a magnetic field modulation method capable of overwriting (rewriting) in principle is known as a recording method corresponding to a magneto-optical disk. In the magnetic field modulation method, data is recorded by applying a magnetic field to a magneto-optical disk by a magnetic head and irradiating a recording medium with laser light. In the case of such a magnetic field modulation system, the polarity of the magnetic field is switched at a high speed in synchronization with the data clock. However, generally, if the magnetic field is to be operated at a high frequency, the magnetic field generating mechanism becomes complicated. Therefore, as a countermeasure, for example, it is conceivable to simply increase the modulation frequency for modulating the magnetic field.However, in this case, the magnetic field intensity is insufficient, and it has been found that it is difficult to obtain the magnetic field necessary for recording and erasing. ing. Thus, for example, it is possible to increase the magnetic field strength by increasing the current flowing through the magnetic coil provided in the magnetic head, but in this case, the heat generated by the magnetic coil as a loss increases.

Therefore, it has been proposed to employ a resonance circuit method for generating a magnetic field. According to this resonance circuit method,
Since a large current can be passed through the magnetic coil constituting the magnetic field applying head using the high Q of the resonance circuit,
It is possible to increase the strength of the magnetic field without causing a large power loss.

FIG. 12 shows a configuration example of a recording system as a magneto-optical disk device of a magnetic field modulation system employing a resonance circuit system for generating a magnetic field. In the magneto-optical disk device 200 shown in this figure, the magneto-optical disk 201 is rotated at a constant angular velocity by a spindle motor 202. Also,
On one signal recording surface of the magneto-optical disk 201, a magnetic coil 203 constituting a magnetic field applying head is arranged. At the time of recording, the polarity is set to S pole and N at a bit interval (T) from the magnetic coil 203 by driving of the magnetic coil driver 204.
An alternating magnetic field is generated at the poles.

On the other signal recording surface of the magneto-optical disk 201, an optical head 205 is disposed so as to face the magnetic coil 203. A semiconductor laser (not shown) constituting the optical head 205 is a laser driver 206.
Driven by At the time of recording, the magnetic field generated from the magnetic coil 203 as described above is applied to the magneto-optical disk 2.
01 and the optical head 20
The data recording on the magneto-optical disk 201 is performed by cooperating with the laser light irradiation operation of irradiating the magneto-optical disk 201 with the laser light output from the semiconductor laser No. 5.

An encoder 207 and a timing generator 208 are provided before the laser driver 206.
The encoder 207 adds an error correction code to the input write data WD, and then performs modulation processing to obtain recording data Dr, and outputs the recording data Dr to the timing generator 208. In the timing generator 208, the encoder 207
Data Dr output from the memory and the bit clock signal W
Based on CK, for example, when the recording data Dr is in the state of “1” and “0”, the pulse signal PT having a constant pulse width at the timing when the magnetic field generated by the magnetic coil 203 becomes the S pole and the N pole, respectively. Generate. This pulse signal PT is supplied to the laser driver 206 as a signal for controlling the output timing of the laser light.

The recording operation of the magneto-optical disk device 200 having the configuration shown in FIG. 12 will be described with reference to FIG. For example, assuming that the bit clock signal WCK is a clock signal synchronized with each bit of the recording data Dr output from the encoder 207 and is as shown in FIG.
A clock signal CK2 obtained by dividing the clock signal WCK shown in FIG. Therefore, the magnetic coil 203 forming the magnetic field application head is
As shown in FIG. 3 (c), an alternating magnetic field whose polarity alternates between the S pole and the N pole at the bit interval (T) is obtained.

Further, for example, write data WD supplied from a host computer is supplied to an encoder 207, and is modulated after adding an error correction code, and
Data (recording code sequence) as shown in (d) is formed, and the data is subjected to NRZI modulation. Therefore, from the encoder 207, FIG.
The recording data Dr of the waveform sequence shown in FIG.

The recording data Dr is supplied to a timing generator 2
08. Then, the timing generator 20
As shown in FIG. 13F, when the recording data Dr is in the state “1”, the pulse signal P is generated at the timing when the magnetic field generated by the magnetic coil 203 becomes the S pole.
When the recording data Dr is "0", the pulse signal PT is output at the timing when the magnetic field generated by the magnetic coil 203 becomes the N pole.

The pulse signal PT is supplied to the laser driver 206, and a laser beam is output from the semiconductor laser of the optical head 205 at the timing when the pulse signal PT becomes high level. Therefore, the magneto-optical disk 2
13, a recording mark corresponding to the recording data Dr is formed, as schematically shown in FIG. here,
The hatched circles are the recording marks by the N-pole magnetic field, while the unhatched circles are the recording marks by the S-pole magnetic field.

FIG. 13H shows reproduction data Dp obtained by performing data identification processing on a reproduction signal from the recording mark shown in FIG. 13G, and has the same waveform sequence as the recording data Dr. Data can be obtained.

As described above, by using a recording method using a resonance circuit for generating a magnetic field, the strength of the magnetic field can be increased without generating large heat in the magnetic coil. Further, as a magnetic field modulation system using a resonance circuit for generating a magnetic field, a configuration in which a special coding for adapting the recording data to the resonance circuit system has been proposed, but in the recording system described with reference to FIG. It is not necessary to perform special coding for the recording data to conform to the resonance circuit method. In the following description, for convenience of explanation, a magnetic field modulation method that employs a resonance circuit method for generating a magnetic field as described above is referred to as a “resonance magnetic field modulation method”.

[0013]

As a recording / reproducing format for a disk medium, zone C is used.
The AV system is known. In the zone CAV method, a disk is divided into zones in the radial direction, and recording / reproduction clocks are switched for each zone while recording / reproduction is performed at a constant angular velocity (the clock frequency is increased as moving toward the outer zone). ). That is, in the zone CAV method, high-speed access performance is maintained by rotating the disk at a constant angular velocity, and the clock frequency is increased toward the outer periphery as described above. As a result, even in the recording area on the outer peripheral side where the linear velocity becomes relatively high, the data recording density is increased to about the same level as the recording area on the inner peripheral side, so that high-density recording can be realized. .

However, if the recording method based on the above-described resonance magnetic field modulation method is adopted on the premise of the zone CAV method, the following problem occurs. In the resonance magnetic field modulation method, as can be seen from the description of FIG.
The magnetic field to be applied to the disk is required to be accurately synchronized with the clock of the recording data. When an attempt is made to obtain an alternating magnetic field synchronized with a recording clock signal by a resonance circuit, if the resonance circuit is a so-called LC resonance circuit including LC (inductance and capacitance), the resonance frequency is usually LC
Is fixed by the time constant of Therefore, in a configuration in which a resonance circuit is simply employed for generating a magnetic field, the frequency of the magnetic field, that is, the resonance frequency of the resonance circuit cannot be changed in response to the change of the clock frequency of the recording data. become.

In view of the above-mentioned problems, the present invention has an object to employ a resonance magnetic field modulation method and to make the resonance frequency of a resonance circuit variable according to the clock frequency of variable recording data. I do. Then, at this time, it is an object to enable the resonance frequency of the variably set resonance circuit to be synchronized with the clock with high accuracy.

[0016]

Therefore, a data recording apparatus for recording data on a recording medium by applying a magnetic field to the recording medium by a magnetic head and irradiating the recording medium with a laser beam. As a magnetic head driving device for driving the magnetic head provided in the apparatus, a resonance circuit formed with a resonance coil for generating a magnetic field applied by the magnetic head is synchronized with a data clock of variable recording data. And a resonance frequency varying means capable of varying the resonance frequency of the resonance circuit.

Further, the resonance circuit is formed by connecting a resonance capacitor to an inductor formed including an inductance component of the resonance coil, and a resonance frequency varying means converts a frequency signal corresponding to a data clock of recording data into a signal. On the basis of this, it is configured to variably control the inductance of the inductor. As the resonance frequency varying means, phase comparison means for comparing the phase of the oscillation output generated by the resonance circuit with the frequency signal synchronized with the data clock of the recording data and outputting the phase error information; By changing the inductance of the inductor based on the phase error information, an inductance changing means is provided which variably controls the resonance frequency so that the oscillation output of the resonance circuit is synchronized with the data clock of the recording data.

A resonance coil as an inductor forming a resonance circuit, a magnetic field application coil provided for applying a magnetic field to the disk and forming a part of a magnetic head, and an inductance variable coil whose inductance is variably controlled. The core around which the magnetic field applying coil is wound and the core around which the variable inductance coil is wound are formed so as to be integrated as a core constituting the magnetic head.

According to the above configuration, the frequency variable means capable of varying the frequency of the oscillation signal of the resonance circuit so as to synchronize with the data clock of the variable recording data is provided. The frequency of the magnetic field can be varied so as to be synchronized with the data clock of the recording data. At this time, the resonance circuit is set to L
By forming the C resonance circuit so as to vary the resonance frequency by varying its inductance component, it is possible to provide a relatively simple and low power consumption magnetic field generation mechanism. In addition, as the resonance frequency varying means, the oscillation signal of the resonance circuit is synchronized with the data clock of the recording data based on the phase comparison result between the oscillation signal of the resonance circuit and the frequency signal synchronized with the data clock of the recording data. By employing the configuration of the PLL circuit that variably controls the inductance of the inductor, it becomes possible to synchronize the oscillation signal of the resonance circuit with the data clock of the recording data with high accuracy. Further, the resonance coil forming the resonance circuit is divided into a magnetic field application coil which forms a part of the magnetic head and an inductance variable coil whose inductance is used for varying, and a core around which the magnetic field application coil is wound. By forming the core around which the variable inductance coil is wound so as to be integrated as a core constituting the magnetic head, it becomes possible to generate magnetic fields in a plurality of coils by one core.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic head driving device according to an embodiment of the present invention will be described below. It is assumed that the magnetic head driving device according to the present embodiment is provided in a disk driver capable of recording and reproducing data corresponding to a magneto-optical disk. The following description will be made in the following order. <1. Disc structure><2. Structure of Disk Driver><3. Principle of Variable Resonance Frequency of Resonant Circuit><4. Configuration of Resonance Frequency Variable Circuit in Magnetic Head Driver> (4-1. First Example) (4-2. Second Example) (4-3. Third Example) (4-4. Fourth Example) <5. Configuration example of magnetic head driver>

FIG. 1 conceptually shows a format of a disk to which a disk driver according to an embodiment of the present invention corresponds. A magneto-optical disk (hereinafter, simply referred to as a disk) D shown in this figure corresponds to the zone CAV method. For this reason, the disk D is divided into zones in the radial direction. In this case, for the sake of simplicity, a state is shown in which the zone is divided into three zones Z1, Z2, and Z3 from the inner circumference to the outer circumference. In each zone, a segment SEG divided by a header area HD is formed along the circumferential track direction. For example, data is recorded in a predetermined recording data unit for each segment. In the header area HD, address data, clock pits, servo pits (assuming a sample servo method), and the like are preformatted in advance by emboss pits and the like. The disk D is driven to rotate at a constant angular velocity, and recording and reproduction are performed based on a predetermined data clock set so that its frequency increases as the zone moves from the inner peripheral zone to the outer peripheral zone. Thereby, the data recording linear density is made constant on the inner peripheral side and the outer peripheral side. In this figure, each segment SEG
, The state in which the same number of recording marks are recorded indicates that the recording linear density is constant. In order to cope with such a zone CAV method, the disk driver of the present embodiment records and reproduces data while switching so that the clock frequency increases for each zone from the inner circumference to the outer circumference. I will go. In this figure, the tracks are concentric for the sake of convenience. However, in the present embodiment, the tracks may be formed in a spiral shape as a matter of course.

<2. Structure of Disk Driver> FIG.
FIG. 1 is a block diagram illustrating a configuration example of a disk driver according to an embodiment of the present invention. The disk driver 10 shown in this figure has a spindle motor 11 for driving the disk D to rotate. The disk D is formatted in accordance with the zone CAV method as described above, and during recording and reproduction, the spindle motor 11 is used.
The motor is driven to rotate at a constant angular velocity. Although not shown here, a frequency generator (FG) is attached to the rotation shaft of the spindle motor 11, and a frequency signal output from the frequency generator is supplied to a servo controller 17 described later as rotation information.

The magnetic head 12 is a magnetic head driver 1
3 drives the disk D during recording.
, An alternating magnetic field is applied. In the present embodiment, a resonance circuit is provided as the magnetic head driver 13, and the operation of the resonance circuit is configured to generate an alternating magnetic field from the magnetic head 12. A configuration that can be changed so as to synchronize with the magnetic head 12 and the magnetic head driver 13 will be described later.

The optical head 14 includes a semiconductor laser that outputs laser light, an objective lens that serves as an output end of the laser light, and a photodetector that detects light reflected from the disk D as a photocurrent. The semiconductor laser is driven by a laser driver 16, which performs on / off control and output level control of laser light output from the semiconductor laser. The magnetic head 12 and the optical head 14 are disposed to face each other with the disk D interposed therebetween.

The clock signal CK2 is supplied to the magnetic head driver 13 during recording. Clock signal C
K2 is obtained by dividing a clock signal (bit clock signal) WCK, which is synchronized with each bit of the recording data Dr output from the encoder described later, by 1/2.

The pulse signal PT is supplied to the laser driver 16 during recording. As will be described later, during a recording operation based on the resonance magnetic field modulation method of the present embodiment, the polarity is S at the bit interval (T) from the magnetic head 13.
An alternating magnetic field that alternates between the pole and the N pole is generated. When the recording data Dr is "1" and "0" as shown in FIG. It is output at the timing when the magnetic field becomes the S pole and the N pole.

The disk driver 10 has a CPU (C
and a servo controller 17 including an central processing unit. Servo controller 17
Are supplied with a focus error signal FE and a tracking error signal TE. The servo controller 17 executes tracking servo control and focus servo control based on the input focus error signal FE and tracking error signal TE, and further executes the radial control of the optical head 15 under the control of a system controller described later. Executes movement control in the direction. The spindle motor 11 is controlled by the servo controller 17 based on the frequency signal from the frequency generator, and is controlled so that the disk D rotates at a constant angular velocity during recording or reproduction as described above.

The system controller 18 comprises a CPU and controls the entire system of the disk driver shown in FIG. This system controller 18 includes:
A key input unit 19 for the user to perform various operations related to the recording / reproducing operation, a data buffer 20 for storing data at the time of required data processing, and a SCSI for transmitting and receiving data and commands to and from the host computer. Small
Computer System Interface) The interface 21 and the like are connected. Further, the encoder, the decoder, the ECC circuit, and the data buffer 20 are interconnected via a data bus 30.

Further, at the time of recording, the system controller 18 generates a bit clock signal WCK synchronized with each bit of the recording data and supplies it to the encoder 23 and the timing generator 24. In this embodiment, the bit clock signal WC corresponds to the zone CAV method.
K is variable according to the zone on the disk D where data is to be recorded. This variable processing is realized, for example, by the system controller 10 identifying a zone on the disk D currently being accessed by the optical head based on address data transmitted from the address decoder 25. In other words, if the processing is performed so as to divide the resonance frequency of the internal reference oscillator by the required division ratio in accordance with the zone identified by the system controller 18, for example, The bit clock signal WCK can be obtained.

Also, from the system controller 18,
A clock signal CK2 having a frequency obtained by dividing the bit clock signal WCK by 及 び and a phase adjustment offset signal OFS having a preset value suitable for each zone are supplied to the magnetic head driver 13. Note that the clock signal CK2 naturally has a variable frequency based on the frequency of the bit clock signal WCK that is variable corresponding to each zone. The clock signal C
K2 is also output to the timing generator 24.

ECC (Error Correction Code) circuit 22
Is the SCSI interface 2 from the host computer.
In addition to performing an error correction code adding process on the write data supplied through 1, an error correction process is performed on output data of a decoder 29 described later.

The encoder 23 performs a predetermined modulation process on the write data to which the error correction code has been added by the ECC circuit 22, obtains a recording code sequence, and further applies NRZI (Non Return to Zero) to the recording code sequence. Inverted)
The modulated data is output as recording data Dr. The recording data Dr is input to the timing generator 24. Here, the description of the configuration inside the timing generation circuit 24 is omitted, but the input recording data Dr, the bit clock signal W
CK and clock signal CK2 (FIGS. 13A and 13B)
13 (e)), when the recording data Dr (FIG. 13 (e)) is in the state of "1" and "0" as shown in FIG.
The generated magnetic field (FIG. 13C) generates a pulse signal PT which is output at a timing when it becomes an S pole and an N pole.

Disk D output from optical head 15
, Ie, the photocurrent detected by the photodetector is supplied to the RF amplifier 15. The RF amplifier 15 performs current-voltage conversion on the input photocurrent, and generates necessary signals such as an RF signal, a push-pull signal, and a focus error signal FE through arithmetic processing of signals from the respective light receiving regions.

The focus error signal FE among the various signals generated by the RF amplifier 15 is supplied to the servo controller 17 to form a servo loop for performing the focus servo control as described above. . The RF signal and the push-pull signal are supplied to the address decoder 25 and the comparator 26. The address decoder 25 extracts, for example, address data from the supplied RF signal and
To supply.

The comparator 26 binarizes the RF signal and outputs it to a PLL (Phase Locked Loop) circuit 27 and a D flip-flop 28. The PLL circuit 27 controls the resonance frequency of the internal oscillator based on the phase comparison result between the binarized RF signal and the oscillation output,
By performing frequency division processing with a predetermined frequency division ratio, a servo clock SCK synchronized with the RF signal is generated. In the frequency dividing process, based on the address data transmitted from the address decoder 25, the system controller 10 identifies a zone on the disk D currently being accessed by the optical head, and a clock frequency suitable for the identified zone. Is achieved by the system controller 10 executing control to set the frequency division ratio so that Also,
The PLL circuit 27 generates a reproduction data clock RCK by dividing the frequency of the servo clock SCK, for example.

The servo clock SCK is supplied to the system controller 10 and also to the above-mentioned address decoder 25 as an operation clock. Further, the reproduction data clock RCK is output from the system controller 10.
To be used for timing control of a required reproduction process, and the D flip-flop 28 and the decoder 29
Is supplied as an operation clock.

The D flip-flop 28 latches the binarized signal from the comparator 26 with the reproduced data clock RCK to obtain reproduced data Dp, and transmits it to the decoder 29. The decoder 29 performs, for example, NRZI inverse conversion processing on the reproduction data Dp output from the D flip-flop 28 to obtain a recording modulation code string of a predetermined format, and then performs demodulation processing on the recording modulation code string. To obtain playback data. The reproduced data is subjected to error correction processing and the like by the ECC circuit 22 and then transmitted and output to the host computer via the SCSI interface 21.

Since the recording operation by the disk driver 10 having the above-described configuration may be performed in accordance with the resonance magnetic field modulation method described above with reference to FIG. 13, the detailed description is omitted here. However, in the present embodiment, zone C
In order to support the AV system, as a recording operation shown in FIG. 13, a bit clock signal WCK (FIG. 13) synchronized with each bit of the recording data is provided for each zone where data is recorded.
(A)) becomes variable. Accordingly, in response to this, the clock signal CK2 obtained by dividing the bit clock signal WCK by １ ／
(FIG. 13 (b)), and the disk D
(FIG. 13 (c)) is also varied for each zone. In addition, FIG.
(E) The recording data Dr shown in (f) and the cycle of the pulse signal PT output from the timing generator 33 are also variable. As a result, for example, the recording linear density of the recording mark shown in FIG. 13G is kept substantially constant from the inner peripheral side to the outer peripheral side.

<3. Principle of Variable Resonance Frequency of Resonant Circuit>
Since the disk driver 10 of the present embodiment employs the resonance magnetic field modulation system, the magnetic head 12 generates an alternating magnetic field by the operation of the resonance circuit provided in the magnetic head driver 13. Then, in order to cope with the zone CAV method, a configuration is adopted in which the resonance frequency of the resonance circuit is changed in conformity with the clock frequency set for each zone.

Here, consider the case where the resonance frequency of the resonance circuit is varied. Here, assuming that a so-called LC resonance circuit formed by impedance elements of inductance and capacitance is adopted as the resonance circuit, the resonance frequency f of this LC resonance circuit is:

(Equation 1) Thus, the resonance frequency of the LC resonance circuit can be varied by changing the inductance (L) or the capacitance (C). For example, in order to variably control the capacitance (C), it is conceivable to use an element such as a varicap. However, there is almost no element capable of handling a large current in the varicap or the like. Is not preferred. Therefore, in the present embodiment, a method of varying the inductance (L) will be adopted in consideration of practicality as a magnetic head driver.

Here, the inductance as a resonance circuit in the magnetic head driver is actually a coil wound around a core as a magnetic head. In the present embodiment, by utilizing this, the inductance of the resonance circuit is changed by changing the magnetic permeability μ of the core material, thereby changing the resonance frequency of the resonance circuit. It is generally known that the magnetic permeability μ of the core material changes linearly with respect to the magnetic flux. Since the rate of change of the magnetic permeability μ is proportional to the degree of magnetic saturation, in order to obtain a high magnetic permeability μ, for example, the cross-sectional area of the core is reduced, or the core is made of a material that meets the required conditions. Then, a condition that easily causes magnetic saturation may be given.

FIG. 3 conceptually shows the relationship between the current level flowing through the coil and the magnetic flux generated in the coil. For example, in the event that the current level is positive, the magnetic flux changes as shown in the figure according to the coil current. Here, the magnetic permeability μ corresponds to the slope of the curve shown in FIG. Thus, it can be seen that as the level of current flowing through the coil increases, the state approaches the state of magnetic saturation, and the magnetic permeability μ accordingly decreases. Since the inductance L of the coil is substantially proportional to the magnetic permeability μ, the inductance μ of the coil is varied by varying the coil current level to vary the magnetic permeability μ.
Can be variably controlled.

Therefore, if the amplitude level of the AC component of the coil current is assumed to be limited to the vicinity of the range A in FIG. 3, for example, the resonance circuit of the resonance circuit is formed based on the circuit configuration shown in FIG. It is possible to change the inductance L. In FIG. 4, a resonance coil L is provided in a core CR.
1 is wound. The resonance coil L1 is connected to the capacitor C to form a parallel resonance circuit. Actually, the magnetic head 12 is constituted by the core CR and the resonance coil L1. That is, an alternating magnetic field corresponding to the resonance frequency of the resonance circuit generated from the resonance coil L1 wound around the core CR corresponds to the magnetic field applied to the disk. In this figure, the illustration of an oscillation circuit for the resonance circuit (L1, C) is omitted for the sake of simplicity. A control coil L2 is wound around the core CR in addition to the resonance coil L1. The control coil L2 is supplied with a DC control current iDC for variable inductance control via an AC blocking coil L2. Here, by appropriately setting the level of the control current iDC, the condition of the magnetic saturation of the core CR changes, and for example, the operation center point of the alternating current flowing through the resonance circuit is shifted between the point a and the point b in FIG. As a result, the magnetic permeability μ can be variably controlled. That is, the resonance frequency of the resonance circuit can be variably controlled by changing the inductance of the resonance coil L1. Note that the above description is merely a principle, and in order to actually apply the magnetic head driver 13 of the present embodiment, the coil current must be appropriately adjusted in accordance with the amplitude in the range up to the negative region. A configuration for generating an alternating magnetic field that alternates between the S pole and the N pole is adopted.

<4. Configuration of Resonance Frequency Variable Circuit in Magnetic Head Driver> (4-1. First Example) Next, a specific configuration example of the resonance frequency variable circuit applied as the magnetic head driver 13 will be sequentially described. FIG. 5 is a circuit diagram showing a configuration of a resonance frequency variable circuit as a first example, and the same parts as those in FIG. In FIG. 5, a resonance coil L1 for applying a magnetic field is applied to the core CR.
Are wound to form the magnetic head 12. In this case, a series connection circuit of the coil L2b, the resonance coil L1, and the coil L3b is formed, and the resonance capacitor C is inserted at both ends of the series connection circuit. That is, in this case, the coil L2b, the resonance coil L1, and the coil L3
b, an inductance component formed by series connection of b.
A parallel resonance circuit is formed by the capacitance of the resonance capacitor C. In this figure, the illustration of the oscillation drive circuit for the resonance circuit is omitted for the sake of simplicity.

The coil L2b is wound around the same core together with the control coil L2a to form an inductor L2. Similarly, the coil L3b and the control coil L3a are wound around the same core to form an inductor L3. ing. The control coil L2a and the control coil L3a are connected in series with the AC blocking coil Ls as shown in the figure. A DC current iDC is supplied to a series connection circuit including the AC blocking coil Ls, the control coil L2a, and the control coil L3a, as shown in FIG. Here, the control coil L
2, L3 and the inductance of the AC blocking coil Ls are set so that Ls≫L2, L3 holds.

In such a configuration, when a DC control current iDC is applied to a series connection circuit composed of an AC blocking coil Ls, a control coil L2a, and a control coil L3a, the control coil according to the principle described with reference to FIG. L2b,
The inductance of L3b is varied, and at this time, the resonance circuits (L1, L2b, L3b,
C), the control coil L2
b and L3b act to be magnetized in opposite directions. That is, the control coils L2b and L3b perform operations corresponding to the positive quadrant and the negative quadrant, respectively, of the coil current in FIG. Thus, the magnetic head 12 generates an alternating magnetic field in which the S pole and the N pole alternately appear depending on the resonance frequency of the resonance circuit.

The resonance circuit (L1, L2b, L
3b, C) is equal to the coil L2b (L2) −
Since the resonance coil L1-coil L3b (L3) is connected in series,

(Equation 2) The inductance of the inductors L2 and L3 is varied by the supply of the direct current iDC as described above, so that the resonance circuit (L1, L2b, L3b) expressed by the above (Equation 2) is obtained. , C) resonance frequency f
Can be variably controlled.

(4-2. Second Example) FIG. 6 is a circuit diagram showing a configuration of a resonance frequency variable circuit as a second example.
The same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. In this figure, the oscillation drive circuit for the resonance circuit is not shown. In FIG. 6, both ends of a resonance coil L1 for applying a magnetic field and a control coil L
2 and L3, respectively, DC blocking capacitors Cs
1 and Cs2 are inserted. An AC blocking coil Ls2 is connected in parallel to the resonance coil L1 via the DC blocking capacitors Cs1 and Cs2. In this case, for the parallel resonance circuit (L1, L2, L3, C), the resonance current iAC is L1-Cs1-L as shown in the figure.
By flowing through 2-CL-Cs2, the control coil L
2 and L3 are magnetized in opposite polarities with respect to the resonance current iAC. The DC control current iDC is
It is made to flow through Ls1-L2-Ls2-L3. In the second example, the DC blocking capacitor Cs (C
s1, Cs2) and the resonance capacitor C, Cs≫C is established, and for the AC blocking coil Ls (Ls1, Ls2) and the resonance coil L1, required values are selected for each element such that Ls≫L is established. Is performed. Further, for the AC blocking coil Ls (Ls1, Ls2) and the control coils L2, L3, required values are selected so that Ls≫L2, L3 is satisfied.

Also in this second example, the resonance frequency f is expressed by the same (Equation 2) as in the first example, but with the above-described configuration, the control coils L2 and L3 forming the parallel resonance circuit are controlled. By supplying the current iDC, the inductance of the control coils L2 and L3 is varied, so that the resonance frequency f is varied.

(4-3. Third Example) FIG. 7 is a circuit diagram showing a configuration of a resonance frequency variable circuit as a third example.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. Also in this figure, the oscillation drive circuit for the resonance circuit is not shown. In this figure, a coil L2b forming an inductor L2 and an inductor L2
3 are connected in parallel to a parallel resonance circuit composed of the resonance coil L1 and the resonance capacitor C, respectively. Also in the third example, the control coil L2
DC current iDC is supplied to a series connection circuit of a (inductor L2), control coil L3a (inductor L3) and AC blocking coil Ls as in the case of FIG. Further, a DC blocking coil Ls and an inductor L2
As for the relationship with (L2a, L2b) and L3 (L3a, L3b), each of the above elements is selected so that Ls≫L2, L3.

In the case of the circuit configuration shown in FIG.
1 and the coils L2b and L3b form a parallel connection circuit, and the resonance frequency f of the resonance circuit becomes

(Equation 3) Will be represented by Therefore, the change characteristic with respect to the direct current iDC in the circuit of FIG. 7 is opposite to the case of the circuit of FIG. 5 in which the resonance coil L1 and the coils L2b and L3b are connected in series. In this case, too, the control coils L2a and L2
By supplying the control current iDC to 3a, the inductances of the inductors L2 and L3 can be varied, whereby the resonance frequency of the resonance circuit represented by the above (Equation 3) is variably controlled. Become.

(4-4. Fourth Example) FIG. 8 is a circuit diagram showing a configuration of a resonance frequency variable circuit as a fourth example.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. Also in this figure, the illustration of the oscillation drive circuit for the resonance circuit is omitted. In this figure, for a parallel resonance circuit consisting of a resonance coil L1 and a resonance capacitor C, a series connection circuit consisting of a control coil L2-DC blocking capacitor Cs1 and a control coil L3-DC blocking capacitor Cs2 as shown in FIG. Are connected in parallel. Therefore, the resonance frequency f of the resonance circuit shown in this figure is also represented by the above (Equation 3). In this case, the control current iDC is the AC blocking coil Ls
-It is supplied so as to flow through the control coil L2-control coil L3.

In the circuit shown in this figure, the relationship of Cs≫C holds for the DC blocking capacitor Cs (Cs1, Cs2) and the resonance capacitor C, and the DC blocking coil Ls and the control coil Ls
2 and L3, the above elements are selected so that the relationship of Ls≫L2, L3 is satisfied.

In the resonance circuit shown in FIG.
2, L3, by supplying a control current iDC to vary the inductance of the control coils L2, L3.
It becomes possible to variably control the resonance frequency f represented by (Equation 3).

For example, FIG. 10 shows the characteristics of a resonance frequency variable circuit as a fourth example. As shown in this figure,
As the DC control current iDC is increased, the inductance L (actually, the control coil L
2, the variable by L3) decreases as shown by the solid line in the figure, and accordingly, the resonance frequency f of the resonance circuit previously expressed by (Equation 3) becomes a broken line curve. It is controlled to rise as shown. Therefore, in the actual magnetic head driver 13, for example, FIG.
As shown in the figure, a predetermined control current iDC level is set as an operation center point Cnt, and various necessary component elements are selected such that the control current iDC can be varied within a required range with reference to the operation center point Cnt. In such a manner that the variable range of the resonance frequency can be covered.

<5. Configuration Example of Magnetic Head Driver> As the magnetic head driver 13 of the present embodiment, for example, any one of the above-described resonance frequency variable circuits of the first to fourth examples is employed, and then the resonance frequency is varied. The resonance frequency variably set by the circuit (that is, the magnetic head 12
It is necessary to provide a configuration in which the phase of the magnetic flux generated by the recording data Dr always follows the bit clock signal WCK of the recording data Dr. From then on,
A specific configuration example of the magnetic head driver 13 according to the present embodiment will be described with reference to FIG. 9, taking as an example a case where the resonance frequency variable circuit as the fourth example shown in FIG. 8 is employed. In FIG. 9, the same portions as those in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted.

The magnetic head driver 13 shown in FIG. 9 includes a phase comparator 1, a low-pass filter 2, a synthesizer 3, and a variable oscillation circuit 4. Also, in the variable oscillation circuit 4, the magnetic head 12 formed so that the resonance coil L1 is wound around the core CR is shown. An alternating magnetic field generated by the operation of a magnetic head driver 13 described below is applied to the disk D from the magnetic head 12, and for example, a laser beam emitted from the optical head 14 as shown in FIG. Data recording is performed by using the light in combination with the light.

A clock signal CK2 supplied from the system controller 18 is input to the phase comparator 1 as a reference signal, and the oscillation output of the variable oscillation circuit 4 (resonance output of the resonance circuit) is compared by a comparator 4a to form a rectangular wave. Are input as comparison signals.
The clock signal CK2 is a bit clock signal WCK having a frequency synchronized with each bit of the recording data Dr as described above.
Is a signal obtained by dividing the frequency by 1/2, and is a frequency signal synchronized with the recording data Dr. Also, the bit clock signal WCK
Is variable, and is changed and set for each zone in which data is to be recorded. Therefore, the frequency of the clock signal CK2 is also variable corresponding to each zone in which data is to be recorded.

The phase comparator 1 compares the clock signal CK2 with the oscillation output of the variable oscillation circuit 4 and outputs an error information signal indicating the phase error to the low-pass filter 2. The low-pass filter 2 extracts the low-frequency component of the error information signal and outputs it to the synthesizer 3.

In the synthesizer 3, the low-frequency component of the phase error signal output from the low-pass filter 2 and the offset signal OF supplied from the system controller 18 are output.
S is synthesized, and the synthesized output is output as a DC control current iDC for varying the resonance frequency of the variable oscillation circuit 4.

In the variable oscillation circuit 4, the resonance circuit and the resonance frequency variable circuit (L
1, C, L2, L3, Cs1, Cs2, Ls) are provided with an oscillation drive circuit for a resonance circuit. The oscillation drive circuit shown in this figure includes a transistor Q, a base resistor R1, a feedback coil Lf, a resistor R2, and an AC blocking decoupling coil Lc. The collector of the transistor Q is connected to the center tap provided in the resonance coil L1, so that the transistor Q is connected to the power supply line V via the tap winding of the resonance coil L1 and the decoupling coil Lc. Further, the collector of the transistor Q is branched and connected to the non-inverting input of the comparator 4a via a series connection of a resistor R3-coupling capacitor Cc, so that the oscillation output of the variable oscillation circuit 4 is connected to the comparator 4a. To supply it. In this case, the non-inverting input of the comparator 4a is grounded. The base of the transistor Q is connected to one end of the feedback coil Lf via the base resistor R1 and to the power supply line V via the starting resistor R2. The other end of the feedback coil Lf is grounded. The emitter of transistor Q is grounded with respect to ground.

The feedback coil Lf is connected to the core CR together with the resonance coil L1, so that an alternating output having the same frequency as the resonance output obtained by the resonance coil L1 by the exciting action is applied to the feedback coil Lf. Will be transmitted. Then, as a result of the alternating output obtained by the feedback coil Lf flowing to the base of the transistor Q, the parallel resonance circuit (L1, C, L2, L3) shown in FIG.

In the magnetic head driver 13 having the above configuration, as a basic operation, the phase of the clock signal CK2 compared by the phase comparator 1 and the phase of the oscillation output output from the variable oscillation circuit 4 converge so as to be locked. Operation will be performed. That is, the level of the control current iD varied according to the phase error detected by the phase comparator 1
When C is supplied to the control coils L2 and L3 in the variable oscillation circuit 4, the resonance frequency of the resonance circuit is changed to the clock signal CK.
And operates to match the clock frequency of 2.
The operation is performed so as to converge so that the phase difference between the two becomes zero. That is, the magnetic head driver 13 of the present embodiment operates the variable oscillation circuit 4 like a VCO (however, in this case, the current control is performed by the control current iDC), so that the resonance frequency of the resonance circuit is As a PLL circuit for synchronizing with the clock signal CK2. When the PLL circuit as the magnetic head driver 13 is locked, a state in which the resonance frequency of the resonance circuit is synchronized with the clock signal CK2 is always stably obtained.

The offset signal OFS synthesized by the synthesizer 3 with the output of the low-pass filter 2 is used for recording on a disk D compatible with the zone CAV method.
A signal for adjusting the phase difference between the recording data Dr and the magnetic field applied to the disk so as to conform to the actual recording characteristics. For example, a predetermined value suitable for each zone of the disk D is set in advance. It is said.

When the magnetic head driver 13 is configured in this manner, even if the frequency of the clock signal CK2 is variable for each zone where data is recorded, the P
By the operation of the LL circuit, the resonance frequency of the resonance circuit is constantly changed so as to be synchronized with the clock signal CK2. That is, the alternating magnetic field applied to the disk D from the magnetic head 12 can be synchronized with the recording data Dr so as to follow the clock frequency switched for each zone. Thus, for example, data recording by the resonance magnetic field modulation method according to the method shown in FIG. 13 can be performed in accordance with the zone CAV method.

As can be seen from the above description, of the elements forming the resonance circuit and the resonance frequency variable circuit, the resonance coil L1 and the control coil (inductor) L
2 and L3 are wound around a core to generate a required magnetic field component. For example, the cores on which these coils are wound may be provided independently, but in this case, the magnetic head 12 or the magnetic head driver 13 becomes larger due to the necessity of a plurality of cores. This is not preferable from the viewpoint of miniaturization of the circuit scale. Therefore, for example, FIG.
By configuring the magnetic head 12 with the structure shown in FIG. 1, it is possible to integrate at least the core around which the resonance coil L1 and the control coils L2 and L3 are wound.

FIGS. 11A and 11B are a side view and a plan view showing a portion of the core CR as the magnetic head 12. FIG.
The core CR is provided with bobbins B1 and B2 on the left and right of the upper part of the core body as shown in the figure. The control coil L2 is wound around the bobbin B1, and the control coil L3 is wound around the bobbin B2 in a required winding direction. Then, from the state where the control coils L2 and L3 are wound in this way, the resonance coil L1 is wound around the periphery as shown in the figure. In this way, the resonance coil L1 and the control coils L2 and L3 are wound around the integrated core, so that at least the resonance coil L1
1. The number of cores around which the control coils L2 and L3 are wound is one, and the magnetic head 12 (and the magnetic head driver 13) can be prevented from increasing in size.

It should be noted that the recording code string after modulation, such as the (1, 7) modulation method or the (2, 7) modulation method, is used by the applicant as the resonance magnetic field modulation method shown in FIG. An invention has been proposed in which data can be recorded in accordance with a recording code modulation method in which an inversion interval based on an even-numbered bit interval appears as a (run-length limited code sequence). It is of course possible to configure the disk driver 10 provided so that data can be recorded according to the configuration of the present invention. The present invention is not limited to the recording method specifically shown in FIG. 13, but can be applied to another magnetic field modulation recording method employing a configuration in which a magnetic field is generated by a magnetic head by a resonance circuit.

[0069]

As described above, the present invention provides a data clock for recording data in which the resonance frequency of a resonance circuit formed with a resonance coil for generating a magnetic field applied by a magnetic head is made variable. , The period of the alternating magnetic field applied to the disk is
The recording data can be changed in synchronization with the data clock. Thereby, for example, the zone C in which the clock frequency is variably switched for each zone
It is possible to perform data recording by the resonance magnetic field modulation method in correspondence with the AV method.

A resonance circuit is formed by connecting a resonance capacitor to an inductor serving as a resonance coil as a resonance circuit.
By variably controlling the inductance of the inductor based on the clock frequency of the recording data, it is possible to variably control the resonance frequency with a simpler and simpler configuration than, for example, variably controlling the capacitance of the resonance capacitor. Become. Then, the inductance of the inductor is varied based on the phase error information of the frequency signal synchronized with the oscillation output generated by the resonance circuit and the data clock of the recording data, whereby the oscillation output of the resonance circuit becomes the data clock of the recording data. By adopting a configuration as a PLL circuit in which the resonance frequency is variably controlled so as to be synchronized, it is possible to synchronize the data clock and the magnetic field with high accuracy.

Further, a resonance coil divided into a magnetic field application coil and a variable inductance coil is wound around one core, and one core generates a magnetic field corresponding to the purpose of a plurality of coils. By configuring
This has the effect that the number of cores required as a mechanism for varying the resonance frequency can be reduced and the circuit can be reduced in size.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a format of a disk according to a zone CAV method supported by a disk driver according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a disk driver according to the embodiment;

FIG. 3 is an explanatory diagram showing a relationship between a coil current, a magnetic flux, and a magnetic permeability of a core.

FIG. 4 is a circuit diagram for explaining the principle of changing the resonance frequency of the resonance circuit.

FIG. 5 is a circuit diagram showing a first example of a resonance frequency variable circuit as a magnetic head driver according to the embodiment.

FIG. 6 is a circuit diagram showing a second example of the resonance frequency variable circuit as the magnetic head driver according to the embodiment.

FIG. 7 is a circuit diagram showing a third example of a resonance frequency variable circuit as a magnetic head driver according to the embodiment.

FIG. 8 is a circuit diagram showing a fourth example of the resonance frequency variable circuit as the magnetic head driver according to the embodiment.

FIG. 9 is a circuit diagram showing a configuration example of a magnetic head driver configured based on a resonance frequency variable circuit as a fourth example.

FIG. 10 is an explanatory diagram showing the relationship between the inductance of the resonance circuit and the resonance frequency with respect to a control current (DC current) for varying the inductance in the resonance frequency variable circuit of the fourth example.

11A and 11B are a side view and a plan view showing a structural example as a magnetic head.

FIG. 12 is a block diagram illustrating a configuration example of a disk device using a resonance magnetic field modulation method.

FIG. 13 is a timing chart showing an example of a recording operation using a resonance magnetic field modulation method.

[Explanation of symbols]

1 phase comparator, 2 low-pass filter, 3 synthesizer,
4 Variable oscillation circuit, 4a comparator, 10 disk driver, 11 spindle motor, 12 magnetic head, 13 magnetic head driver, 14 optical head, 1
5 RF amplifier, 16 laser driver, 17 servo controller, 18 system controller, 19 key input section, 20 data buffer, 21 SCSI interface, 22 ECC circuit, 23 encoder,
24 timing generator, 25 address decoder, 26
Comparator, 27 PLL circuit, 28 D flip-flop, 29 decoder, 30 data bus, WCK
Bit clock signal, CK2 clock signal, Dr
Recording data, Dp playback data, RCK playback clock, SCK servo clock, FE focus error signal, TE tracking error signal, D disk,
Z1, Z2, Z3 zones, HD header area, SEG
Segment, RM recording mark, CR core, OFS
Offset signal, L1 resonance coil, L2, L3, L
2a, L3a Control coil (inductor), L2b, L
3b coil, Ls, Ls1, Ls2 AC blocking coil, C resonance capacitor, Cs1, Cs2 DC blocking capacitor, Lf feedback coil, Q transistor, B
1, B2 bobbin,

Claims (4)

[Claims] 1. A data recording apparatus for recording data on a recording medium by applying a magnetic field to the recording medium by a magnetic head and irradiating the recording medium with a laser beam. A magnetic head driving device for driving the head, a resonance circuit formed with a resonance coil for generating a magnetic field applied by the magnetic head, and a resonance circuit formed in synchronization with a data clock of variable recording data. A magnetic head driving device comprising: a resonance frequency varying unit capable of varying a resonance frequency of a resonance circuit. 2. The resonance circuit is formed by connecting a resonance capacitor to an inductor formed including an inductance component of the resonance coil, and the resonance frequency variable unit corresponds to a data clock of the recording data. 2. The magnetic head driving device according to claim 1, wherein an inductance of the inductor is variably controlled based on a frequency signal. 3. The phase comparison means for performing phase comparison between an oscillation output of the resonance circuit and a frequency signal synchronized with a data clock of the recording data, and outputting phase error information, Inductance varying means for variably controlling the resonance frequency so as to synchronize the oscillation output of the resonance circuit with the data clock of the recording data by varying the inductance of the inductor based on the phase error information. 3. The magnetic head drive device according to claim 2, wherein: 4. The resonance coil as the inductor,
A magnetic field application coil provided to apply a magnetic field to the disk and forming a part of a magnetic head, and an inductance variable coil whose inductance is variably controlled; a core around which the magnetic field application coil is wound; The magnetic head driving device according to claim 2, wherein a core around which the variable inductance coil is wound is formed integrally as a core constituting a magnetic head.