JPH03203849A - Clearance control method for magnetic head for magneto-optical recording - Google Patents

Abstract

PURPOSE:To satisfactorily control the clearance of a magnetic head for magneto-optical recording by using the following-up property of clearance control of an optical head. CONSTITUTION:When an objective lens holder 13 is moved downward from a neutral point, an optical head reflection mirror 51 fixed to this holder 13 is moved in the same direction by the same extent, and a detecting beam 61 is made incident as a spot on a position off the center of a two-divided photo diode 41 for optical head, and the output of a difference signal 71 from this photo diode 41 is negative. Meanwhile, a difference signal 73 of a photo diode 43 for magnetic head which detects the reflected light from a magnetic head reflection mirror 53 is 0 because a magnetic head arm 17 is at a neutral point. Difference signals 71 and 73 are compared with each other by a comparing circuit 75, and the difference signal between them is used as the error signal to drive a magnetic head actuator 21 so that the error signal is 0. Thus, the clearance between the magnetic head and a recording face is accurately kept.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the clearance between a magnetic head and a magneto-optical recording medium in magneto-optical recording.

In conventional magneto-optical recording, it is necessary to drive both the optical head and the magnetic head close to the magneto-optical recording medium, and controlling the clearance with the recording medium becomes a problem.

Regarding clearance control between the optical head and recording medium,
Technology has already been established in the field of optical recording that detects focusing errors and drives a drive unit equipped with an objective lens to follow the surface runout of the recording medium. can be tracked with an accuracy of approximately 0.5 μm.

On the other hand, in a hard disk drive, a magnetic head is assembled into an air slider and held by a pressure arm and a gimbal spring, and the dynamic pressure of the air generated by the rotation of the disk is used to generate zero pressure.
．． A technology has been established that allows a magnetic head to fly above a hard disk with a gap of about 2 μm.

However, even if an attempt is made to directly apply the above-mentioned floating magnetic head used in a hard disk drive to magneto-optical recording, satisfactory results are not always obtained.

Magneto-optical recording media have lower precision than hard disks, resulting in larger surface runout, and hard disks are not strictly controlled to prevent dirt and dust. Therefore,
With a small flying height of about 0.2 μm, there is always a risk of head crash, damaging the recording medium, and making stable driving impossible. Furthermore, if there is a risk of head crash, the magnetic head must be moved away from the disk, which requires a strong magnetic field, which increases inductance and makes it difficult to override at high speeds by magnetic field modulation recording.

The present invention focuses on followability of clearance control of an optical head and uses this followability to realize good clearance control of a magnetic head in magneto-optical recording.

The clearance control method for a magnetic head in magneto-optical recording according to the present invention is such that the magnetic head is driven so that the distance to the magneto-optical recording medium becomes a set value, following fluctuations in the distance to the magneto-optical recording medium. An optical head reflecting element for measuring the amount of movement in the direction of the magneto-optical recording medium is provided in the driving part of the optical head, and a magnetic head reflecting element for controlling the amount of movement in the direction of the magneto-optical recording medium is provided in the driving part of the magnetic head. The optical head reflection element is irradiated with a light beam for relative position detection to detect the reflected light, and the magnetic head reflection element is irradiated with a light beam for relative position detection to detect the reflected light. The relative position with the drive unit via the magneto-optical recording medium is detected, and the magnetic head drive unit follows the movement of the optical head drive unit so that the relative position between the optical head drive unit and the magnetic head drive unit remains constant. It is characterized by driving a head driving section.

FIG. 1 is a perspective view illustrating an embodiment of the magnetic head clearance control method of the present invention, FIG. 2 is a plan view thereof, and FIG.
The figure is also a side view.

A magnetic head 19 and an objective lens holder 13 are mounted on the carriage 11. The objective lens halter 13 constitutes an optical head together with an objective lens actuator (not shown), and those conventionally used in optical recording or magneto-optical recording can be used as they are. The magnetic head 19 is attached to a magnetic head actuator 21 via an arm 17.

In magneto-optical recording, a recording and reproducing beam 27 from a light source 23 is raised by a recording and reproducing raising mirror 25, and a spot is irradiated onto a disk 29 (magneto-optical recording medium) by an objective lens 15, so that information can be recorded and reproduced. has been done. The magnetic head 19 is driven for access following the objective lens 15 and records information. In this magneto-optical recording, the objective lens 15 detects a focusing error from the reflected light of the recording and reproducing beam 27 from the recording surface of the disk 29, and the distance from the disk 29 is strictly controlled by a focus signal, approximately 0. It is driven with a tracking accuracy for surface runout of .5μ■.

In this embodiment, the magnetic head 19 is controlled by detecting the movement of the optical head that follows the surface runout, specifically, the movement of the objective lens holder 13 in the direction of the disk 29 (surface runout tracking amount). Also, part of the light from the light source 23 is used as this detection light.

The relative position detection beam 55 extracted as surplus light from the light source 23 is split by the beam splitter 31 into an optical head detection beam 61 and a magnetic head detection beam 63. The detection beam 61 for the optical head passes through the reflection mirror 33 and the first raising mirror 25, and is reflected by the optical head reflection mirror 51 fixed to the objective lens holder 13, and this reflected light is divided into two parts for the optical head. The light is incident on the photodiode 41 (light detection element) and detected. On the other hand, the magnetic head detection beam 63 is connected to the second rising mirror 37.
The light beam is raised by the magnetic head and is reflected by the magnetic head reflection mirror 53 fixed to the magnetic herad arm 17, and this reflected light enters the two-split photodiode 43 for the magnetic head, which is a detection element.

Now, as shown in FIG. 4A, the objective lens holder 13 follows the surface deflection of the disk 29 by the focus signal.
Let us consider the case where the movement is downward (13→13'). When the objective lens holder 13 is at the neutral point, the optical head detection beam 61 from the first upright mirror 33 is incident on the center of the optical head two-split photodiode 41 as shown by the - dotted chain line. When the objective lens holder 13 moves downward, the optical head reflection mirror 51 fixed to it also moves in the same direction and by the same amount, lowering to the position shown by the two-dot chain line (51→51'), and the detection beam 61 is 6
As shown by 1', the light is reflected by the optical head reflection mirror 51', and the light beam is incident as a spot on a position shifted from the center point of the two-split photodiode 41 for the optical head. Therefore, the output of the difference signal 71 from the two-split photodiode 41 for the optical head becomes negative.

On the other hand, at this time, since the magnetic herad arm 17 is at the neutral point, the difference signal 73 of the magnetic head photodiode 43 that detects the reflected light from the magnetic head reflection mirror 53 is zero. Therefore, the comparison circuit 7 compares the difference signal 71 and the difference signal 73.
5, and using these difference signals as an error signal, the magnetic RAD actuator 21 is driven so that the error signal becomes zero.

At this time, as shown in FIG. 4B, the magnetic held arm 17 is moved downward by the magnetic held actuator 21, and the error signal becomes zero at a position where the lens actuator 17 is moved by the amount of movement of the objective lens holder 13. .

As described above, the magnetic helad arm 17 always follows the movement of the objective lens holder 13, ensuring a constant relative position, and as a result, the clearance between the magnetic head 19 and the disk 29 is maintained constant. Furthermore, since the surplus light from the recording and reproducing light source is used, a dedicated light source is not required and the weight can be reduced.

According to the present invention, the optical head drive section and the magnetic head drive section are driven to follow the movement of the drive section of the optical head, which is driven so that the distance from the magneto-optical recording medium is constant. By driving the magnetic head drive unit so that the relative position of the magnetic head is constant, the clearance of the magnetic head to the disk can be increased.
The height of the magnetic head can be controlled in a closed loop while indirectly detecting the height, and the clearance with the disk can be freely set. Moreover, since the optical head drive unit follows the recording surface rather than the disk surface, the clearance between the magnetic head and the recording surface can be accurately maintained regardless of the thickness of the disk substrate.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram (perspective view) showing an embodiment of the present invention;
The figure is a plan view, FIG. 3 is a side view, and FIGS. 4A and 4B are explanatory diagrams showing the operating method. 11... Carriage 13... Objective lens holder 15... Objective lens 17... Magnetic herad arm 19... Magnetic head 21... Magnetic helad actuator 23... Light source 25... Recording Raising mirror for reproduction 27... Beam for recording and reproduction 29... Disk 31
...Beam splitter 33...Reflection mirror 35.
...First standing mirror 37...Second standing mirror 4
1...Two-split photodiode 43 for optical head...
-Two-split photodiode 51 for magnetic head...Optical head reflection mirror 53...Magnetic head reflection mirror 55...Beam 61 for relative position detection...Beam 63 for optical head detection...For magnetic head detection beam

Claims (1)

[Claims] 1. A magneto-optical recording medium is attached to a drive section of an optical head that is driven so that the distance to the magneto-optical recording medium becomes a set value in accordance with changes in the distance to the magneto-optical recording medium. An optical head reflective element is provided to measure the amount of movement in the direction, and a magnetic head reflective element is provided in the drive section of the magnetic head to control the amount of movement in the direction of the magneto-optical recording medium.The optical head reflective element is provided with a light beam for relative position detection. irradiates the magnetic head reflective element and detects the reflected light, and also irradiates the magnetic head reflective element with a relative position detection light flux to detect the reflected light, and the An optical device that detects a relative position, follows the movement of the optical head drive unit, and drives the magnetic head drive unit so that the relative position between the optical head drive unit and the magnetic head drive unit becomes a constant value. A method for controlling the clearance of a magnetic head in magnetic recording. 2. The reflected light from the optical head reflecting element and the reflected light from the magnetic head reflecting element are detected by separate light detecting elements, and the light detecting element is detected as the optical head drive unit moves from the neutral point position. 2. The magnetic head clearance control method according to claim 1, wherein the magnetic head drive section is driven and controlled by the difference signal.