JPH0660538A - Magnetic field modulation type magneto-optical disk device - Google Patents

Abstract

PURPOSE:To prevent head crash with simple constitution by eliminating the need of controlling the speed of raising and lowering a magnetic head for modulating magnetic field in the case of raising and lowering the head with respect to a disk. CONSTITUTION:A magnetic field modulation type magneto-optical disk device is provided with the magnetic head 4 which floats by dynamic pressure by the rotation of a magneto-optical disk, and the head 4 is raised and lowered with respect to the magneto-optical disk 1 by a magnetic head raising and lowering mechanism 7. When the head 4 is moved between a retracting position and a usable position, a CPU 9 interrupts the rotation servo of a spindle motor 2 by making a switch 10 off and transmits an instruction to a motor driving circuit 14 so as to make the revolving speed of the disk 1 higher than that in the case of normal use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overwritable magnetic field modulation type magneto-optical disk device having a floating magnetic head.

[0002]

2. Description of the Related Art In a magneto-optical disk device, a recording film composed of a perpendicularly magnetized film such as a Tb-Fe thin film is formed on a transparent disk-shaped substrate, and a light spot is focused by a condenser lens via an optical head. By irradiating the magneto-optical recording film through the transparent substrate at the same time, by applying a bias magnetic field in the perpendicular direction to the magneto-optical recording film by the bias magnetic field generating coil,
The magnetization direction of the recording film is recorded as recording data in the light spot irradiation portion.

In such a magneto-optical disk device,
A magnetic field modulation method is an example of an overwritable recording method. In this magnetic field modulation method, when rewriting information, the recording film is irradiated with a spot of a laser beam focused by a condenser lens, and at the same time, a magnetic field for magnetic field modulation is applied by a magnetic head for magnetic field modulation, Data is recorded as the direction of magnetization of the recording film.

However, in the magnetic field modulation method as described above,
When recording information, it is necessary to apply a large magnetic field to the magneto-optical recording film, and to increase the switching speed of the magnetic field in order to increase the recording density. Therefore, a magnetic field modulation magnetic head mounted on a floating head slider as used in a magnetic disk device is used.

In a magneto-optical disk apparatus using a floating head slider as a magnetic head for magnetic field modulation, a contact start / stop method has been conventionally used as a head start / stop method. In this contact start stop method, when the rotation of the disk is stopped, the floating head slider and the disk are placed in contact with each other, the rotation of the disk is started, and the floating head slider is levitated as the number of rotations increases to perform normal recording / reproduction, etc. When the disk is stopped again, the rotation speed of the disk is lowered and the floating head slider is landed on the disk. In this case, the floating head slider and the disk surface go through the steps of contact, low speed sliding, separation, low speed sliding, and contact.

The contact start / stop system is
Although the structure of the mechanism is simple, there is a possibility that the magnetic head may be attracted to the disk because it slides in contact at a low speed. Therefore, in order to solve this problem, a method has been proposed in which the disk is rotated and then the magnetic head is lowered toward the disk. For example, Japanese Patent Laid-Open No. 3-88185 discloses a device for moving a floating head slider up and down using a piezo element. Further, as a mechanism for moving the floating head slider up and down, Japanese Patent Laid-Open No. 3-73449 discloses a mechanism in which the head is moved up and down by controlling the temperature of a shape memory alloy with a Peltier element. In this way, by rotating the disk and then moving the magnetic head up and down, the disk and the magnetic field modulation magnetic head can be kept in a non-contact state at all times.

[0007]

However, in the method of moving the magnetic head for magnetic field modulation up and down while the disk is rotated as described above, when the floating force obtained by the floating head slider is small, the speed at which the head is lowered is set. However, if the speed is relatively fast, there is a large possibility of head crash.

That is, in the system in which the head is moved up and down while the disk is rotating, once the head descends, a stable flying height of the head can be secured thereafter, and it is relatively strong against vibration and shock. . However, in a transient situation where the head is lowered (landing) on the disk or lifted (lifted up) from the disk, the flying state of the head becomes unstable. If you do not properly control the speed at which the head moves up and down, head crash may occur. Further, when controlling the speed of raising and lowering the head, there are problems that it is difficult to control appropriately according to the situation, and the apparatus configuration becomes complicated.

The present invention has been made in view of these circumstances, and when the magnetic head for magnetic field modulation is moved up and down with respect to the disk, it is not necessary to control the speed at which the head is moved up and down, and the structure is simple. It is an object of the present invention to provide a magnetic field modulation type magneto-optical disk device capable of preventing a head crash and stably raising and lowering the head.

[0010]

A magnetic field modulation type magneto-optical disk device according to the present invention comprises a floating magnetic head which is levitated by a dynamic pressure caused by rotation of the magneto-optical disk, and a magnetic head which opposes the magnetic head with the magneto-optical disk interposed therebetween. In an apparatus having an optical head for irradiating the magneto-optical disk with a light spot, the number of rotations of the magneto-optical disk is normally set when the floating magnetic head is moved between a retracted position and a usable position. It is provided with a disk rotation speed control means for making it higher than when in use.

[0011]

When the floating magnetic head is moved between the retracted position and the usable position, the rotation speed of the magneto-optical disk is set higher than that during normal use by the disk rotation speed control means. Then, the relative speed between the magneto-optical disk and the floating magnetic head increases, and the floating force received by the floating magnetic head increases.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to a first embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of a magneto-optical disk device, and FIG.
Is a diagram showing the relationship between the rotational speed of the spindle motor for rotating the disk and the torque, FIG. 3 is a flowchart showing the operation when lowering the magnetic head, and FIG. 4 is a flowchart of the spindle motor during operation according to the flowchart of FIG. FIG. 5 is a waveform diagram showing a change in the number of revolutions, and FIG. 5 is a flowchart showing an operation when the magnetic head is raised.

With reference to FIG. 1, the structure of the part related to the vertical movement of the magnetic head of the magnetic field modulation type magneto-optical disk device will be described. A spindle motor 2 for mounting and rotating the magneto-optical disk 1 is provided, and a frequency generator (FG) 3 as a speed detector for detecting the rotation speed of the spindle motor 2 is connected to the spindle motor 2.

In the vicinity of the magneto-optical disk 1, a magnetic head 4 and an optical head 5 are provided so as to face each other with the magneto-optical disk 1 in between. The magnetic head 4 is attached to a gimbal spring 6 and is connected to a magnetic head up-and-down mechanism 7 to form a floating head slider that slightly floats above the surface of the magneto-optical disk 1 to perform recording / reproduction. There is. The magnetic head up-and-down mechanism 7 is composed of a known mechanism disclosed in JP-A-3-88185 and JP-A-3-73449. The magnetic head up / down mechanism 7 is connected to a magnetic head up / down mechanism drive circuit 8 for driving the up / down mechanism.
According to an instruction from U9, the magnetic head 4 is moved up and down to move between the retracted position and the usable position.

On the other hand, the frequency generator 3 is connected to an FG amplifier 11 via a switch 10, where the rotation speed detection signal of the spindle motor 2 is amplified and input to one input end of a comparison circuit 12. It has become so. The rotation reference signal generator 13 is connected to the other input terminal of the comparison circuit 12 so that the rotation reference signal is input. The output of the comparison circuit 12 is supplied to a motor drive circuit 14 that drives the spindle motor 2, and the spindle motor 2 is rotationally driven according to the comparison result of the rotation speed detection signal and the rotation reference signal. It is like this. The CPU 9 serving as a disk rotation speed control means includes a switch 10 and a motor drive circuit 14.
The rotation servo of the spindle motor 2 is turned on / off by opening / closing the switch 10, and the rotation speed of the spindle motor 2 is set.

In this embodiment, the spindle motor 2 is OF
F, that is, when the rotation of the magneto-optical disk 1 is stopped, in order to prevent the magnetic head 4 from sticking to the magneto-optical disk 1, the magnetic head 4 is separated from the disk from the floating position. When the spindle motor 2 is started, the spindle motor 2 is turned on with the rotation servo of the spindle motor 2 turned off. At this time, the switch 10 is opened according to an instruction from the CPU 9 to turn off the rotation servo of the spindle motor 2. In this case, since the rotation speed detection signal from the frequency generator 3 is cut off, the rotation information of the spindle motor 2 is not transmitted to the comparison circuit 12, and the rotation servo of the motor is not applied.

Then, the spindle motor 2 continues to be fully accelerated, the rotational speed of the spindle motor 2 becomes higher than the rotational speed during recording / reproduction (steady rotational speed), and the magneto-optical disk 1 and the magnetic head 4 move relative to each other. The speed is higher than that during steady rotation. Here, the relationship between the rotational speed of the spindle motor 2 and the torque is shown in FIG. The steady rotation speed B, which is the rotation speed at the time of recording / reproducing, is set so that there is some torque so that the rotation servo can be applied. A range (B ±
ΔB) is a readable / writable area. When the rotation servo is turned off by such a motor, the motor accelerates to the vicinity of the maximum rotational speed C.

Further, while the spindle motor 2 is being accelerated, the magnetic head 4 which moves integrally with the optical head 5 is moved to the maximum position of the disk so that the relative speed between the magneto-optical disk 1 and the magnetic head 4 becomes maximum. Move it to the outer circumference. In this way, the magnetic head 4 moves to the outermost circumference, and the rotation speed of the spindle motor 2 (that is, the rotation speed of the magneto-optical disk 1) is close to the maximum rotation speed C.
When the magnetic head vertical rotation number A is exceeded), the magnetic head 4 is lowered and floated on the magneto-optical disk 1.

In the floating head slider floating above the surface of the magneto-optical disk 1, among the flying height σ of the head, the relative speed v between the disk and the head, the area T of the floating head slider, and the pressing force f of the head, σ = k · (v · T ³ / f) ^1/2 (1) However, since k has a relationship of a predetermined coefficient, the rotational speed of the disk (that is, the relative speed v between the disk and the head) is 2 If you double it, the flying height of the head will be double the route. Further, at this time, when the head is lowered to the same height, the floating force received by the head (force in the direction opposite to the head pressing force amount f) doubles.

The operation of lowering the magnetic head 4 as described above is shown in FIG. First, in step S1 (hereinafter, steps are omitted), the rotation servo of the spindle motor 2 is turned off, and in step S2, the spindle motor 2 is turned on with the rotation servo turned off. Then, the rotation speed of the spindle motor 2 increases up to around the maximum rotation speed C. next,
In S3, the optical head 5 and the magnetic head 4 are moved to the outermost circumference of the magneto-optical disk 1, and in S4, it is determined whether the magnetic head 4 is located in the outermost circumference of the magneto-optical disk 1 and the number of rotations of the spindle motor 2. It is determined whether or not a predetermined magnetic head vertical rotation speed A close to the maximum rotation speed C is exceeded, and if at least one of them is not satisfied, S4 is repeated. The magnetic head 4 is located at the outermost circumference of the magneto-optical disk 1,
When the rotation speed of the spindle motor 2 becomes equal to or higher than the predetermined magnetic head vertical rotation speed A, the process proceeds to S5, where the magnetic head 4 is lowered and floated on the magneto-optical disk 1.

After that, the rotation servo of the spindle motor 2 is turned on to restore the steady rotation speed B so that the normal use such as recording / reproducing can be performed. That is, in S6, the switch 10 is closed and the rotation servo of the spindle motor 2 is turned on.
Then, in S7, it is judged whether or not the predetermined steady speed B ± ΔB is reached, and when the steady speed B is returned, the spindle motor 2
Startup is completed. When the switch 10 is closed, the comparison circuit 12 compares the rotation speed detection signal from the frequency generator 3 with the rotation reference signal from the rotation reference signal generator 13 to rotate the spindle motor 2 so as to match the steady rotation speed B. Drive is controlled.

FIG. 4 shows changes in the rotation speed of the spindle motor 2 at this time. When the spindle motor 2 is turned on with the rotation servo turned off, the rotation speed of the spindle motor 2 increases from (a) to around the maximum rotation speed C. here,
If the rotation servo of the spindle motor 2 is turned on at the point (c) where the magnetic head 4 starts to descend at a point (b) where the predetermined magnetic head vertical rotation speed A is exceeded and the magnetic head 4 has finished descending, a steady rotation occurs. The rotation speed of the motor decreases toward the number B. From the point (d) where the rotation speed falls within the range of B ± ΔB, the READY state is in which normal use is possible, and the rotation speed of the spindle motor 2 converges to the steady rotation speed B.

For example, the maximum rotation speed C of the motor is about 650.
Set 0 rpm spindle motor 2 to steady speed B = 3600
Consider the case of a device used at ± 10 rpm. At this time,
When the predetermined magnetic head vertical rotation speed A = 6000 rpm is set, the magnetic head 4 descends after 6000 rpm or more. Therefore, even when the head is descended at the same radius on the disk, the steady state is obtained from the equation (1). The flying height is at least 29% greater than that during rotation, and the flying force is 67% greater when the distance from the disk is the same, which greatly reduces the risk of head crash.

The operation of raising the magnetic head 4 will be described with reference to FIG. When the magnetic head 4 is moved up, the same procedure as when lowering the head is performed. First, in step S11, the optical head 5 and the magnetic head 4 are moved to the outermost periphery of the magneto-optical disk 1,
In S12, it is determined whether or not the magnetic head 4 is located at the outermost circumference of the magneto-optical disk 1. If the head is not located at the outermost circumference, S1 is determined.
Repeat 2. When the magnetic head 4 is located on the outermost circumference of the magneto-optical disk 1, the process proceeds to S13, and the rotation servo of the spindle motor 2 is turned off. Then, the rotation speed of the spindle motor 2 increases up to around the maximum rotation speed C. Then S
At 14, it is determined whether or not the rotation speed of the spindle motor 2 exceeds a predetermined magnetic head vertical rotation speed A, and if it exceeds, the process proceeds to S15 to raise the magnetic head 4. Then S
By turning off the spindle motor 2 at 16,
The spindle motor 2 stops.

In this way, also when the magnetic head 4 is raised, similarly, the rotational speed of the spindle motor 2 is increased to a predetermined magnetic head vertical rotational speed A close to the maximum rotational speed C, and the relative speed between the disk and the head is increased. With the speed increased, the flying force of the head is increased to raise the magnetic head 4.

As in the present embodiment, when the magnetic head 4 is moved up and down with the number of revolutions of the spindle motor 2 being higher than that during normal use such as recording / reproducing, the magnetic head 4 is placed on the magneto-optical disk 1. The relative speed between the disk and the magnetic head when descending or rising from above the magneto-optical disk 1 becomes larger than that during steady rotation. When the relative speed between the disk and the magnetic head is large, the levitation force received by the magnetic head increases.Therefore, when the head moves up and down at the same speed, the possibility of head crash is extremely small, and the head can be moved up and down stably. Is possible.

Further, even if the head is moved up and down at a high speed, the head does not easily crash, so that it is not necessary to control the speed at which the head is moved up and down, and the magnetic head up-and-down mechanism can have a simple structure. For example, in the past, a bimorph was used, and a means for controlling the head descending speed by delicately controlling the applied voltage was used.However, even in such a case, the voltage applied state and the non-applied state are simply switched by a switch or the like. Will improve It is also possible to use an inexpensive solenoid head up / down mechanism without using a bimorph.

When there is a possibility that a disc that is not compatible with overwriting may be used, first the spindle motor is started at a constant rotation speed, the control track is read, and the floating head may cause a head crash. Determine if there is no disc. And
If the disk does not have a head crash,
As in the present embodiment, the rotation servo of the spindle motor may be turned off to increase the rotation speed of the motor, and the operation of lowering the magnetic head may be started.

FIG. 6 is a flow chart showing the operation of lowering the magnetic head of the magneto-optical disk apparatus according to the second embodiment of the present invention.

The second embodiment is an example applied to a magneto-optical disk device in which the number of rotations can be switched depending on the disk.
The configuration of the device is the same as that of the first embodiment, and the description is omitted.

For example, in the case of a device capable of switching between 3600 rpm and 1800 rpm depending on the disc performance (sensitivity, surface wobbling, etc.), when a disc for 1800 rpm is mounted as shown in the flow chart of FIG. First, the magnetic head is lowered while being rotated at 3600 rpm.

First, in S21, the rotation speed of the spindle motor 2 is set to 3600 rpm, and in S22, the spindle motor 2 is turned on to rotate the disk at 3600 rpm. In this embodiment, the rotation servo of the spindle motor 2 remains ON. Then, in S23, the optical head 5 and the magnetic head 4 are moved to the innermost circumference of the magneto-optical disk 1, the control track is read in S24, and S2
Recognize whether the disc mounted in step 5 is a 1800 rpm disc or a 3600 rpm disc.

Then, in S26, the optical head 5 and the magnetic head 4 are moved to the outermost circumference of the magneto-optical disk 1, and S2
In S28, it is determined whether or not the magnetic head 4 is located on the outermost periphery of the magneto-optical disk 1, and in S28, the number of rotations of the spindle motor 2 is 3
Whether or not the speed is 600 ± 10 rpm is determined, and when the conditions are not satisfied, the steps are repeated. The magnetic head 4 is located on the outermost periphery of the magneto-optical disk 1, and the rotation speed of the spindle motor 2 is 3600 ± 1.
When the speed reaches 0 rpm, the process proceeds to S29, where the magnetic head 4 is lowered and floated on the magneto-optical disk 1.

Next, in S30, it is judged whether or not the mounted disk is a disk for 1800 rpm based on S25,
In the case of a disk for 1800 rpm, the process proceeds to S31 and the rotation speed of the spindle motor 2 is set to 1800 rpm.
Then, the spindle motor 2 is controlled to rotate at 1800 rpm. Then, in S32, it is determined whether or not the rotation speed of the spindle motor 2 is 1800 ± 10 rpm, and when the rotation speed falls within the range of 1800 ± 10 rpm, the startup of the spindle motor 2 is completed. On the other hand, 3 at S30
If a disk for 600 rpm is installed, it is not necessary to reset the rotation speed of the spindle motor 2, so
At this point, the startup of the spindle motor 2 is completed.

Thus, in this embodiment, 1800 rpm
Even when using a disk for use as a disk, first, the spindle motor 2 is accelerated to 3600 rpm to increase the relative speed between the disk and the magnetic head, and then the magnetic head 4 is lowered to float on the magneto-optical disk 1. To do so. After that, the number of rotations of the spindle motor 2 is reduced to 1800 rpm, and recording / reproduction is performed. This makes it possible to prevent the occurrence of head crash when the magnetic head 4 is moved up and down with respect to the disk even when the disk for low rotation is used.

Other functions and effects are similar to those of the first embodiment.

In the case of an apparatus using a CLV disk in which the linear velocity at which the head traces a recording track at the time of recording / reproducing is used, the occurrence of head crash when the magnetic head is moved up and down is prevented as follows. can do.

In the case of a magneto-optical disk device for a CLV disk, the linear speed is increased by increasing the rotation speed of the spindle motor when the head is on the inner circumference side and lowering the rotation speed of the spindle motor when the head is on the outer circumference side. Is kept constant. However, when moving the magnetic head up and down with respect to the disk, the movable part composed of the optical head and the magnetic head is moved to the outer peripheral side, the linear velocity control is released, and the spindle motor is moved to the inner peripheral side. Rotate at the number of rotations. As a result, since the head is located on the outer peripheral side in a state where the rotation speed of the spindle motor is large, the linear velocity is increased, and the magnetic head is moved up and down in this state.

Therefore, since the relative speed between the disk and the magnetic head is higher than that at the time of recording / reproducing, the flying height of the magnetic head is increased, and it is possible to prevent problems such as head crash from occurring.

[0040]

As described above, according to the present invention, when the magnetic head for magnetic field modulation is moved up and down with respect to the disk, it is not necessary to control the speed for moving the head up and down, and the head has a simple structure. There is an effect that a crash can be prevented and the head can be stably raised and lowered.

[Brief description of drawings]

1 to 5 relate to a first embodiment of the present invention,
FIG. 1 is a block diagram showing the configuration of a magneto-optical disk device.

FIG. 2 is a diagram showing the relationship between the rotational speed and torque of a spindle motor that rotates a disk.

FIG. 3 is a flowchart showing an operation when lowering a magnetic head.

4 is a waveform diagram showing changes in the rotation speed of the spindle motor during operation according to the flowchart of FIG.

FIG. 5 is a flowchart showing an operation when raising a magnetic head.

FIG. 6 is a flowchart showing an operation of lowering the magnetic head of the magneto-optical disk device according to the second embodiment of the present invention.

[Explanation of symbols]

 1 ... Magneto-optical disk 2 ... Spindle motor 4 ... Magnetic head 5 ... Optical head 7 ... Magnetic head up / down mechanism 8 ... Magnetic head up / down mechanism drive circuit 9 ... CPU 14 ... Motor drive circuit

Claims (1)

[Claims] 1. A floating magnetic head that floats by dynamic pressure caused by rotation of a magneto-optical disk, and an optical head that is provided to face the magnetic head with the magneto-optical disk interposed therebetween and irradiates a light spot on the magneto-optical disk. In a magnetic field modulation type magneto-optical disk device having: a disk rotation speed control for increasing the rotation speed of the magneto-optical disk when moving the floating magnetic head between a retracted position and a usable position. A magnetic field modulation type magneto-optical disk device comprising means.