JPH03183003A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute recording at high speed with high reliability by detecting electrostatic capacity between an electrode, which is provided in a slider, and a conductor film on a recording medium by an electrostatic capacity detection part and controlling the intensity of a magnetic field, which is impressed to a recording film, to be almost constant based on this detection signal. CONSTITUTION:When a magneto-optical disk 10 starts rotation, a slider 7 floats up by an air current flowing between the disk 10 and the slider 7. At such a time, an electrode 6 of the slider 7 and a conductor film 3 of the disk 10 form a capacitor and the electrostatic capacity is detected by an electrostatic capacity detection part 12. Generally, since an inversely proportional relation is established between the electrostatic capacity and a distance between electrodes, the change of the distance between the electrode 6 and the conductor film 3 can be detected as the change of the electrostatic capacity. In such a way, feedback control is executed to suspension pressure by a suspension pressure control part 13 based on the signal detected by the electrostatic capacity detection part 12 so that a gap length can be fixed. Thus, since the gap length is kept constant, the intensity of the magnetic field to be impressed from a magnetic head 8 to a recording film 2a is almost fixed and recording is executed at high speed with high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device for recording, erasing, and reproducing information.

[Conventional technology]

A magneto-optical disk device will be described as an example of a magnetic recording/reproducing device.

Magneto-optical disk drives are being standardized for practical use as rewritable high-density, large-capacity storage devices, but in recent years, research into high-speed data transfer using overwriting has been active with the aim of further improving performance. It is being done. and,
The most promising method for this overwriting is a magnetic field modulation method in which an electromagnet is used in the magnetic head to apply a reversal magnetic field to the magneto-optical disk in accordance with recorded information.

By the way, the electromagnet for the above-mentioned magnetic head is disclosed in Japanese Unexamined Patent Publication No. 62
As disclosed in Publication No. 279504, a wire-wound type is being considered, but this type has high impedance, making it difficult to reverse the magnetic field at high speed, and also makes it difficult to efficiently apply the magnetic field to the recording film. Since this is difficult, there are problems such as the drive current for the magnetic head increases and the magnetic head generates heat.

Therefore, in order to efficiently apply a high-speed reversal magnetic field to a magneto-optical disk, Jpn, J, App! .

Phys, 5uppi, 26 (1987) 14
As disclosed in No. 9, a magnetic head is miniaturized to the same size as a hard disk and mounted on a slider, the magneto-optical disk is rotated at high speed, and an air flow flowing between the magneto-optical disk and the slider is used to attach the magnetic head to the slider. While applying levitation pressure, a constant suspension pressure is applied to the slider via the suspension in the opposite direction to the levitation pressure to balance it, and the magnetic head is moved several micrometers to several tens of micrometers from the magneto-optical disk.
A floating magnetic head has been proposed that is made to float with a gap length of .

[Problem to be solved by the invention]

However, in the above-described floating magnetic head, the gap length may vary greatly due to fluctuations in floating pressure.

For example, in the CAV mode in which a magneto-optical disk is rotated at high speed at a constant angular velocity, the linear velocity changes depending on the radial position on the magneto-optical disk, so the floating pressure also varies and the gap length becomes smaller toward the inner circumference. Furthermore, if the magneto-optical disk has uneven defects, the airflow is disturbed there, causing a change in the floating pressure, leading to a variation in the gap length. Furthermore, if the magneto-optical disk has warpage or waviness,
Variations in the gap length occur because the changes in flying pressure do not follow these changes, which is particularly problematic when plastic disk substrates are used.

As described above, when the gap length fluctuates, the magnetic field strength applied to the recording film changes, resulting in unsaturated recording and disturbances in the recording bit shape, which poses the problem of not being able to perform highly reliable recording. .

[Means for Solving the Problems] In order to solve the above problems, the magnetic recording and reproducing device of the present invention is a magnetic recording and reproducing device equipped with a slider for floating a magnetic head above a recording medium. A capacitance detection unit is provided with an electrode on a slider and detects the capacitance between the electrode and a conductive film of the recording medium, and a detection signal from this detection unit is used. The present invention is characterized in that it is equipped with a control means for keeping the magnetic field intensity applied to the recording film almost constant based on the following.

[For production]

According to the above configuration, a recording medium provided with a conductive film is used, an electrode is provided on the slider surface facing the recording medium, and an electrode is provided between the electrode provided on the slider and the conductive film on the recording medium. Since the capacitance is detected by the capacitance detection section, a change in gap length can be detected as a change in capacitance. In addition, since it is equipped with a control means that keeps the magnetic field strength applied to the recording film almost constant based on the detection signal from this detection unit, unsaturated recording and disturbance of the recording bit shape due to fluctuations in the magnetic field strength are less likely to occur. Become.

〔Example〕

As an example of the magnetic recording/reproducing apparatus of the present invention, a magneto-optical disk apparatus will be described below with reference to FIGS. 1 and 2.

In order to record information using the magnetic field modulation method, an auxiliary magnetic field generator 11 that applies a reversal magnetic field according to the recorded information to the magneto-optical disk 10 under irradiation with a constant amount of light beam is as shown in FIG. A magnetic head 8 for generating a magnetic field, a slider 7 equipped with this magnetic head 8, and a magneto-optical disk 10
An electrode 6 provided on a part or the entire bottom surface of the slider 7 facing the slider 7, and a suspension 9 supporting the slider 7.
It is mainly composed of.

Further, a magneto-optical disk 10 as a recording medium used in this apparatus has a recording medium N
2 and conductor M3 are sequentially laminated. Further, the recording medium layer 2 is composed of a recording film 2a made of a magnetic material and a protective overcoat film 2b.

Further, as shown in FIG. 2, a concentric hole is formed in the inner circumference of the magneto-optical disk 10, and a ring-shaped metal hub 4 is fitted into this hole, and a conductive film 3 is fitted into the hole. is shorted to.

Specifically, the conductor 11i3 includes, for example, Au, Cr.
, Affi, conductive metals such as Ag, Pd-Cu, Au-
Metal alloys with excellent wear resistance such as Cu-Co and Ag-Cu-Cd, carbon-metal composite materials such as Ag-C, SnO, I
Good conductive transparent oxides such as n2O3 and In5nO (IT○) are used. These materials are also used as materials for the electrode 6 in FIG. 1, but not necessarily as the conductor g! 3
It is not necessary to choose the same material.

As shown in FIG. 2, the magneto-optical disk 10 is set on a spindle tray 5 for high-speed rotation. At this time, centering is performed by inserting the metal hub 4 into the four parts of the spindle tray 5, and at the same time, the conductive film 3 of the magneto-optical disk 10 is electrically connected to the spindle tray 5 by the metal hub 4. The electrical potential of the conductive film 3 is maintained at the same constant ground potential as that of the spindle saucer portion 5.

When the magneto-optical disk 10 starts rotating, the slider 7 (
The magneto-optical disk 10 (FIG. 1) receives floating pressure from the air flow flowing between the magneto-optical disk 10 and the slider 7, and flies several μm to several tens of μm above the magneto-optical disk. At this time, the electrode 6 provided on the slider 7 and the conductive film 3 of the magneto-optical disk IO form a capacitor, and the capacitance thereof is detected by the capacitance detection section 12. Generally, there is an inversely proportional relationship between the capacitance and the distance between the electrodes, so a change in the distance between the electrode 6 and the conductive film 3 can be detected as a change in capacitance. By the way, since the relative positional relationships between the electrode 6 and the magnetic head 8, and between the conductive film 3 and the recording film 2a do not change, the change in the distance between the magnetic head 8 and the recording film 2a, that is, the gap length This means that the change can be detected as a change in capacitance.

Based on the detection signal detected by the capacitance detection section 12 in this way, the suspension pressure is feedback-controlled by the suspension pressure control section 13 as a control means so that the gap length is constant. This suspension pressure is applied to the slider 7 via the suspension 9 in the opposite direction to the floating pressure.
When the capacitance is larger than the reference capacitance, the gap length is smaller than the reference value, so the suspension pressure is reduced in order to separate the magnetic head 8 from the recording film 2a; conversely, when the capacitance is smaller than the reference capacitance, the gap length is smaller than the reference value. Since the length is larger than the reference value, the suspension pressure is increased to bring the magnetic head 8 closer to the recording film 2a.

In the above way, the gap length is kept constant, so
The strength of the magnetic field applied from the magnetic head 8 to the recording film 2a becomes almost constant, making it difficult for unsaturated recording and disturbances in the shape of recorded bits to occur due to fluctuations in the magnetic field strength. For this reason,
High-reliability high-speed recording can be performed using the floating magnetic head 8.

In the above embodiment, in order to keep the strength of the magnetic field applied from the magnetic head 8 to the recording film 2a almost constant, the suspension pressure is feedback-controlled so that the gap length is constant. Input the above detection signal to the driver circuit that supplies the drive current for generation,
The drive current may be controlled so that the magnetic field strength on the recording film 2a remains constant even if the gap length varies.

In addition, in order to keep the conductive film 3 at a constant potential, a metal hub 4 (FIG. 2) is provided on the magneto-optical disk 10, whereby the conductive film 3 is electrically connected to the spindle saucer portion 5.
Although the conductive film 3 is set to earth potential, it is not necessarily necessary to provide the metal hub 4 on the magneto-optical disk 10. For example,
The conductor film 3 may be held down by a spring-loaded terminal or the like electrically connected to a member having a constant potential, and the specific mode is not limited.

Further, the recording medium layer 2 of the magneto-optical disk 10 is formed into a recording film 2a.
Although the structure is made up of the overcoat film 2b and the overcoat film 2b, a dielectric film or a reflective film may be further provided thereon. vice versa,
The overcoat film 2b may be omitted by allowing the conductor film 3 to play the role of a protective film.

In this embodiment, a magneto-optical disk device has been described, but the present invention can also be applied to a magnetic disk device, etc.

〔Effect of the invention〕

As described above, the magnetic recording/reproducing device of the present invention uses a recording medium provided with a conductive film, and reduces the capacitance between the electrode provided on the slider and the conductive film on the recording medium. Since the capacitance detection section is used for detection, a change in gap length can be detected as a change in capacitance. In addition, since it is equipped with a control means that keeps the magnetic field strength applied to the recording film almost constant based on the detection signal from this detection unit, unsaturated recording and disturbance of the recording bit shape due to fluctuations in the magnetic field strength are less likely to occur. Become. Therefore, highly reliable high-speed recording can be performed using a floating magnetic head.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of an auxiliary magnetic field generator and a magneto-optical disk. FIG. 2 is a schematic longitudinal cross-sectional view showing how the magneto-optical disk is mounted on the spindle tray. 3 is a conductive film, 4 is a metal hub, 5 is a spindle receiver, 6 is an electrode, 7 is a slider, 8 is a magnetic head, 9 is a suspension, 12 is a capacitance detection unit, and 13 is a suspension pressure control unit. be.

Claims (1)

[Claims] 1. In a magnetic recording and reproducing device equipped with a slider that makes the magnetic head float above the recording medium, a recording medium provided with a conductive film is used, and an electrode is provided on the slider, and the electrode and the conductive material of the recording medium are provided. The recording film is equipped with a capacitance detection section that detects the capacitance between the recording film and the recording film, and a control means that keeps the magnetic field strength applied to the recording film almost constant based on a detection signal from this detection section. Features of magnetic recording and reproducing device.