JPH0312003A - Magneto-optical disk device - Google Patents

Abstract

PURPOSE:To eliminate the influence of leakage magnetic field on a magneto-optical recording film and to suppress the generation of heat by offsetting the leakage magnetic field on the magneto-optical recording film from a magnetic circuit with a DC magnetic field from the magnetic circuit to control the position of a magnetic head for magnetic field modulation. CONSTITUTION:The recording, erasure, or reproduction of information is performed by converging a laser beam 22 on the recording film 12 of a magneto-optical disk 11 with the convergence lens 21 of an optical head 24. The magnetic field modulated for recording data is applied on the recording film 12 from a magnetic head 31 for magnetic field modulation. At this time, the position control of the magnetic head 31 is performed by permitting a current to flow on a movable coil 45 corresponding to a position signal detected with a position detector 41. Here, the leakage magnetic field B in a constant direction is generated from the magnetic circuit consisting of a permanent magnet 46 and a yoke 47, and the leakage magnetic field B is offset by adjusting so as to change the direction in an opposite direction with the same strength as that of the leakage magnetic field A of a lens actuator 23 and a positioner 25, etc., at an optical head 24 side, thereby, the influence of the leakage magnetic field on the magneto-optical recording film 12 can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording device, and more particularly to a magneto-optical disk device that can override information using a magnetic field modulation recording method.

[Prior Art] A magneto-optical disk device has a function as a high-frequency modulated magnetic field generator, and overwrites using magnetic field modulation is performed to enable overwriting when rewriting information. There is. That is, in such a magneto-optical disk device, override is performed using magnetic field modulation. This is done by irradiating the recording film of the magneto-optical disk with a laser beam focused by a condensing lens, and at the same time applying a modulated magnetic field according to the recorded data using a magnetic field modulation head. recorded as a direction.

However, magnetic circuits such as a lens actuator that accurately positions the condenser lens and a positioner that positions the entire optical head in the radial direction of the disk generate leakage magnetic fields. For example, depending on the lens actuator,
In some cases, the leakage magnetic field in the recording film reaches several hundred Oe. Such leakage magnetic fields from the magnetic circuit affect the recording film of the magneto-optical disk. In order to eliminate this effect, a bias magnetic field is applied from the magnetic head for magnetic field modulation.
There is a way to offset the leakage magnetic field.

A method of canceling out this leakage magnetic field will be explained using FIG. 4. A leakage magnetic field of magnitude Ha is applied from a lens actuator, a positioner, etc. in a direction perpendicular to the recording film surface, as shown in FIG. 4(a). In order to cancel this leakage magnetic field, as shown in FIG. 4(b), a bias magnetic field of magnitude -Ha, that is, a bias magnetic field of the same magnitude in the opposite direction to the recording film, is applied by a magnetic field modulation magnetic head. do. And when rewriting the information,
As shown in FIG. 4(C), a modulated magnetic field corresponding to the date and time is superimposed on the bias magnetic field. In other words, the magnetic field strength applied from the magnetic head is Hm.

Therefore, the applied magnetic field strength in the direction perpendicular to the recording film surface is:
As shown in Figure 4(d), the sum of magnetic field strengths Ha and Hm,
That is, the magnetic field strength becomes He. That is, by applying a superposition of a bias magnetic field and a modulation magnetic field, the effective magnetic field in the recording film can be modulated around the "0" level, making stable override possible.

By the way, in a magneto-optical disk device, when the position of the magnetic head is fixed in the direction perpendicular to the disk, the distance between the magnetic head and the recording film changes due to surface runout of the disk. If the magnetic head is always driven with the same current at this time, there is a problem that the strength of the magnetic field applied to the recording film fluctuates, deteriorating the recording and reproducing characteristics.

Therefore, the distance between the magnetic head and the recording film is detected, and position control is performed based on the detected position signal so that the amount of spacing between the magnetic head and the recording film is constant. This position control makes the magnetic field strength applied to the recording film constant with respect to the drive current of the magnetic head, achieving high performance.

In this manner, in a magneto-optical disk device, a magnetic head applies a bias magnetic field for canceling a leakage magnetic field, and furthermore, a modulated magnetic field corresponding to recording data is superimposed on the bias magnetic field and applied to the recording film. Furthermore, position control is performed to keep the spacing between the magnetic field modulation magnetic head and the magneto-optical disk constant.

[Problem to be solved by the invention]

In the conventional magneto-optical disk drive described above, a bias magnetic field is applied by a magnetic head to cancel the leakage magnetic field from magnetic circuits such as a lens actuator and a positioner, and a bias magnetic field is applied according to recorded data. Information is rewritten by applying a modulated magnetic field superimposed on a bias magnetic field to the recording film.

However, this method has problems such as a slow magnetic field reversal speed and increased heat generation because a large amount of current is passed through the magnetic head that generates the variable iA magnetic field. Alternatively, the spacing between the magnetic head and the recording film must be reduced, which poses a problem that it is not suitable for actual devices.

In addition, in order to maintain a constant spacing between the magnetic head for magnetic field modulation and the magneto-optical disk, when electromagnetic force is used to drive the magnetic head in a direction perpendicular to the surface of the magneto-optical recording film, a magnetic helad actuator is used. There is a problem in that the leakage magnetic field of the magnetic circuit is applied to the recording film, causing a similar effect.

An object of the present invention is to provide a magneto-optical disk device that can eliminate such drawbacks, suppress heat generation, and eliminate the influence of leakage magnetic fields.

[Means to solve the problem]

The present invention provides an optical head that irradiates a magneto-optical recording film with focused laser light, a high frequency variable IKI magnetic field generating magnetic head that applies a recording magnetic field to the magneto-optical recording film using a magnetic field modulation recording method, and a position detection section that detects a distance to the magnetic recording film; and a drive mechanism that controls the distance of the magnetic head to the magneto-optical recording film to maintain a constant distance based on the position signal detected by the position detection section. Further, the drive mechanism includes a magnetic circuit including a magnet and a yoke that generate a same-temperature magnetic field, and a moving coil disposed within the magnetic circuit and coupled to a magnetic throat. , the magneto-optical disk device that controls the position of the magnetic head, comprising a DC magnetic field generating means for generating a DC magnetic field from the magnetic circuit to the magneto-optical recording film, and the DC magnetic field from the DC magnetic field generating means: It is characterized by eliminating the influence of leakage magnetic fields on the magneto-optical recording film.

[Effect]

In the present invention, a leakage magnetic field from a magnetic circuit such as a lens actuator and a positioner of a magneto-optical disk device to a magneto-optical recording film is suppressed by a magnetic field from a magnetic circuit for controlling the position of a magnetic head for magnetic field modulation. Cancel with DC magnetic field. This cancellation eliminates the influence of the leakage magnetic field in the magneto-optical recording film.

By doing so, only the modulated magnetic field corresponding to the recording data from the magnetic head for magnetic field modulation is applied to the magneto-optical recording film. This allows for stable overrides.

〔Example〕

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

FIG. 1 is a partial cross-sectional view showing one embodiment of the present invention. This magneto-optical disk device includes an optical head 24 that irradiates a recording film 12 of a magneto-optical disk 11 with a laser beam 22;
A high frequency modulation magnetic field generating magnetic node 31 that applies a recording magnetic field to the recording film 12 of the magneto-optical disk 11 by the FF field modulation recording method, a position detection 2J41 that detects the distance of the magnetic head 31 to the recording film 12, and a position detection The drive mechanism includes a drive mechanism that controls the magnetic head 31 to maintain a constant distance from the recording film 12 based on a position signal detected by the device 41.

Furthermore, this drive mechanism is composed of a magnetic circuit consisting of a permanent magnet 46 and a yoke 47 that generate a DC magnetic field, and a moving coil 45 disposed within this magnetic circuit and coupled to the magnetic head 31.

In such a magneto-optical disk device, a magneto-optical disk 1
Information is recorded, erased, or reproduced by condensing a laser beam 22 onto one recording film 12 by a condensing lens 21 of an optical head 24.

Here, the condensing lens 21 is precisely positioned in the focusing direction and the tracking direction by the lens actuator 23 of the optical head 24.

Furthermore, the lens actuator 23 and the condensing lens 2
1, etc., is positioned in the radial direction of the magneto-optical disk 11 by a positioner 25. Here, a leakage magnetic field A in a certain direction generated from the permanent magnets constituting the magnetic circuit of the lens actuator 23 and the positioner 25 is applied perpendicularly to the recording film 12. This leakage magnetic field A is shown in Figure 3 (a
), the size is Ha.

When recording information, the power of the laser convergent light 22 is increased and the recording film 12 is irradiated with it, thereby heating the area to be recorded, and applying a magnetic field modulating magnet to the heated area. A magnetic field H modulated in accordance with recording data is applied from the throat 31 . L data is recorded on this as the direction of magnetization.

Here, the magnetic head 31 for magnetic field modulation includes, for example, as shown in FIG. 2, a core 32 made of Mn-Zn ferrite I, which has low loss and soft magnetism even at high frequencies.
and a winding 33 made of a plurality of stranded thin copper wires.

This magnetic field modulation magnetic head 31 detects the distance to the recording film 12 and performs position control so that the spacing between the magnetic head and the recording film is equal. Here, the distance between the magnetic field modulating magnetic head 31 and the recording film 12 is detected by a position detector 41 such as a reflective sensor or a capacitive sensor. Based on this position signal, the magnetic head 31 is caused to follow the surface runout of the magneto-optical disk 11.

That is, the shaft 43 is attached to the magnetic head/position detector fixing section 42 to which the magnetic head 31 and the position detecting section 41 are attached, and the shaft 43 is held by two leaf springs 44 . A moving coil 45 is attached to the shaft 43 between the two leaf springs 44. Surrounding the moving coil 45,
A magnetic circuit is formed by combining the permanent magnet 46 and the yoke 47. The current flowing through the movable coil 45 is controlled according to the position signal detected by the position detector 41, so that the distance between the magnetic head 31 and the recording film 12 is always equal. That is, by moving the movable coil 45, the magnetic head 3
1 position control is performed.

Here, a leakage magnetic field B in a certain direction is generated from the magnetic circuit consisting of the permanent magnet 46 and the yoke 47. The leakage magnetic field B is
This is shown in FIG. 3(b). This leakage magnetic field B is applied perpendicularly to the recording film 12. Therefore, as shown in FIG. 3(b), the magnitude Hb of the leakage magnetic field B is set to the same intensity as the magnitude Ha of the leakage magnetic field A of the lens actuator 23 on the optical head 24 side, the positioner 25, etc. By adjusting the angles so that they are in opposite directions, the influence of the leakage magnetic field on the recording film 12 is eliminated. for example,
In the case of this example, by using an annular magnet magnetized in the thickness direction, it is possible to generate a leakage magnetic field in the direction perpendicular to the recording film, and its magnitude can also be adjusted appropriately. be. Therefore, the influence of the leakage magnetic field on the magneto-optical recording film can be removed by the direct current magnetic field applied to the magneto-optical recording film from the magnetic circuit.

As a result, the effective magnetic field strength He in the recording film, as shown in FIG. 3(d), is reduced by the modulating magnetic field H generated from the magnetic head for magnetic field modulation, as shown in FIG. 3(c).
, and stable override is possible.

〔Effect of the invention〕

As described above, the present invention cancels the influence of leakage magnetic fields from the lens actuator and positioner on the optical head side on the magneto-optical recording film with the leakage magnetic field from the magnetic circuit that drives the magnetic head for magnetic field modulation. As a result, the influence of the leakage magnetic field on the recording film is eliminated, and stable override is possible using the modulated magnetic field from only the magnetic head for magnetic field modulation. Furthermore, since it is no longer necessary to apply a bias current to the magnetic head for magnetic field modulation, the current flowing through the coil can be reduced, which enables high-speed switching and has the effect of suppressing the rise in temperature of the magnetic head. Furthermore, since the amount of spacing between the magnetic head and the recording film can be increased, the risk of head crash can be reduced and disk replaceability can be easily maintained.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing an example of a magnetic head for magnetic field modulation, and FIG. 3 is an influence of leakage magnetic field according to the embodiment of FIG. 1. FIG. 4 is a diagram for explaining a method for removing the magnetic field, in which (a) is a diagram showing leakage magnetic fields from a lens actuator and a positioner, etc., and (b) is a diagram showing a method for controlling the position of a magnetic head for magnetic field modulation. Diagram showing the leakage magnetic field from the magnetic circuit, (
c) is a diagram showing the modulated magnetic field applied by the magnetic head, (d)
Figure 4 shows the effective magnetic field applied on the recording film surface.
The figures are diagrams for explaining a method conventionally used to remove the influence of leakage magnetic fields. (a) is a diagram showing leakage magnetic fields from a lens actuator, positioner, etc. FIG. 10C is a diagram showing a bias magnetic field applied by a magnetic head, FIG. 3C is a diagram showing a modulation magnetic field applied by a magnetic head, and FIG. 11... Magneto-optical disk 12... Recording film 21... Condensing lens 22... Laser beam 23... Lens actuator 24... Optical head 25... Positioner 31... Magnetic head for magnetic field modulation 32... Mn-Zn ferrite core 33...
・Winding 41...Position detection section 42...Magnetic head/position detector fixing section 43...
... Shaft 44 ... Leaf springs 45, 46, 47, A, B. Moving coil permanent magnet yoke Conventionally existing leakage magnetic field Magnetic head position control unit Magnetic circuit DC magnetic field Modulated magnetic field from the magnetic head

Claims (1)

[Claims] (1) An optical head that irradiates a magneto-optical recording film with a focused laser beam, a high-frequency modulated magnetic field generating magnetic head that applies a recording magnetic field to the magneto-optical recording film using a magnetic field modulation recording method, and the magneto-optical recording of the magnetic head. comprising a position detection section that detects a distance to the film, and a drive mechanism that controls the distance of the magnetic head to the magneto-optical recording film to be kept constant based on the position signal detected by the position detection section; Furthermore, the drive mechanism includes a magnetic circuit including a magnet and a yoke that generate a DC magnetic field, and a moving coil disposed within the magnetic circuit and coupled to the magnetic head, and moves the moving coil to position the magnetic head. The magneto-optical disk device for controlling the magneto-optical disk device includes a direct current magnetic field generating means for generating a direct current magnetic field from the magnetic circuit to the magneto-optical recording film, and the direct current magnetic field from the direct current magnetic field generating means generates a direct current magnetic field to the magneto-optical recording film. A magneto-optical disk device characterized by eliminating the influence of leakage magnetic fields.