JPH02227886A - Head positioning mechanism - Google Patents

Abstract

PURPOSE:To execute a highly accurate positioning and a high-speed access by installing a main actuator to execute an access in a coarse mode and a sub-actuator to be swayingly operated in a fine mode between an access arm and an in-line supporting spring. CONSTITUTION:On plural sheets of magnetic disks 4, sub-actuators 9 and 11 with comparatively high rigidity and light weight are provided in which a sway center member 7 and a pair of piezoelectric elements 8a and 8b displaced in a mutually reverse direction at both sides are made to intervene between a head supporting spring mechanism 3 to support respective magnetic heads 5 and an access arm 2 separately from a sway type main actuator 1 to simultaneously move magnetic heads 5, respectively. All magnetic heads 5 are simultaneously access operated in the coarse mode by the main actuator 1, and thereafter, individual magnetic heads 5 are independently trackingly controlled to the goal tracks in the fine mode by the sub-actuators 9 and 11. Thus, the highly accurate positioning and high-speed access can be executed.

Description

[Detailed Description of the Invention] [Summary] Regarding a head positioning mechanism in a magnetic disk device, etc., the purpose of this invention is to position the head on the data surface of a recording disk with high precision and at high speed. The head positioning mechanism is a head positioning mechanism in which the head is supported via an in-line head support spring mechanism on an access arm that is swung by an actuator in a direction, and the access arm and the head support spring mechanism are connected to a microscopic structure mainly composed of a piezoelectric element. They are connected by a swing actuator, and the head support spring mechanism is configured to be able to swing independently in the radial direction of the disk.

[Industrial application field]

The present invention relates to a head positioning mechanism in a magnetic disk device or the like.

In recent years, with the increase in recording density in the radial direction (track direction) of magnetic disk devices, etc., it has become necessary to position heads more accurately on each recording track of multiple disks. Ru.

[Conventional technology]

In general, methods for controlling the positioning of magnetic heads in magnetic disk drives can be roughly divided into open-loop control using a step motor or the like as a head positioning actuator, and closed-loop control using a voice coil motor (VCM) or the like. There is a method.

The former open-loop control method has a simple actuator configuration and control circuit, but
Alternatively, it has been difficult to increase the track density because it is impossible to correct the case where the positioning of the magnetic head during reading is shifted in the radial direction of the magnetic disk (off-track) due to thermal deformation or the like.

On the other hand, in the latter closed-loop control method, the magnetic head is positioned using servo information recorded in advance on the magnetic disk, so higher track density can be achieved.

[Problem to be solved by the invention]

By the way, in the case of a type in which multiple magnetic heads are arranged on one side of a magnetic disk, such a closed-loop control method has been used to In the case of types equipped with actuators, the mainstream was the servo surface servo method, in which one disk surface for each actuator was used as a servo to control the positioning of the magnetic head using servo information, and the other surfaces were used as data recording surfaces. However, in the case of this method, when the spindle on the magnetic disk side and the shaft on the actuator side are relatively tilted or locally deformed due to thermal deformation of these support structures when writing or reading information, the servo There may be a misalignment between the servo surface and the data surface of the head and the recording/reproducing magnetic head, and there is a risk of off-track, so it is not always easy to increase the recording density.

Therefore, in order to increase the recording density, the actuator is required to have the ability to position the magnetic head with respect to the magnetic disk at high speed and with high precision.

Generally, an access operation by an actuator is performed in a coarse mode for moving the magnetic head to a target track on a magnetic disk at high speed, and a fine mode for causing the magnetic head to follow the target track.

An actuator operating in the coarse mode is required to be able to generate a large acceleration over the entire movement stroke of the magnetic head, so it is necessary to increase the force generated per supplied drive current and reduce the mass of the moving part. It is necessary to obtain a large acceleration by reducing .

On the other hand, in fine mode, the operating distance of the magnetic head is short and does not require much acceleration, but in order to perform highly accurate positioning, a wide control band and a highly rigid structure are required.

Of course, it is not completely open control even in coarse mode, so high rigidity is necessary, but fine mode does not require a wide control band and does not leave vibrations etc. in fine mode that follows coarse mode. Any level is fine.

In the coarse mode, which requires a large output, it is necessary to flow as large a current as possible in both directions, so the power amplifier that drives this is often constructed of an H-type or the like, and the direction of the current is changed by switching. Therefore, such an amplifier has a problem in that it becomes difficult to control extremely small displacements in fine mode due to its dead band and the like.

In view of the above-mentioned conventional problems, the present invention provides a lightweight and rigid mechanism that independently slightly moves the head after it has been moved, in addition to the main actuator that moves the head, thereby moving the head with high precision. It is an object of the present invention to provide a novel head positioning mechanism that enables high-speed positioning.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a head positioning mechanism in which a head is supported via an in-line head support spring mechanism on an access arm that is swung in the radial direction of a recording disk by an actuator. The arm and the head support spring mechanism are connected by a minute swing actuator mainly composed of a piezoelectric element, and the head support spring mechanism is configured to be able to swing independently in the radial direction of the disk.

[For production]

In the present invention, for example, in addition to the swing-type main actuator that simultaneously moves the magnetic heads on a plurality of rotating magnetic disks, there is a mechanism between the head support spring mechanism that supports each magnetic head and the access arm. The configuration includes a swinging center member and a pair of piezoelectric elements disposed on both sides of the swinging center member, which have relatively high rigidity and are lightweight, for minute swinging. After accessing all the magnetic heads on the magnetic disk simultaneously in the coarse mode by the main actuator, each magnetic head is independently moved to displace the pair of piezoelectric elements in the sub actuator in opposite directions to create a swinging center member. Fine mode, in which the track is slightly swung from side to side, is used to control tracking of the target track, enabling highly accurate positioning and high-speed access.

In other words, off-track of the magnetic head due to thermal deformation when writing or reading information is static and only includes low frequency components. The servo head detects the relative deviation of the magnetic head to the target track, and the detection signal causes each magnetic head to follow the target track using the corresponding sub actuator, thereby reducing off-track and increasing the Accurate positioning is possible.

Furthermore, in the data surface servo method, it is possible to position all the magnetic heads using only the main actuator based on servo position information, but it is also possible to simultaneously control each magnetic head to follow each target track using the sub actuator. Therefore, each magnetic head can read and write at the same time and process in parallel, so the transfer speed of the read and write information can be greatly improved.

Furthermore, in the same cylinder in which each magnetic head seeks and reads and writes in parallel to multiple disk surfaces, the parallel reading and writing by each of the magnetic heads can be performed by only a selected magnetic head. Even in the case of switching, there is no need to perform repositioning and writing and reading can be performed immediately, making it possible to improve throughput.

〔Example〕

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

FIG. 1 is a perspective view for explaining one embodiment of a head positioning mechanism according to the present invention.

In the figure, reference numeral 1 denotes a general swing-type main actuator similar to the conventional one, and a plurality of access arms 2 attached to the main actuator 1, and a magnetic field corresponding to each surface of a plurality of magnetic disks 4. The in-line head support spring mechanisms 3 supporting each head 5 are attached to the end portions, in this embodiment, the support spring mechanisms 3 are attached to the base of the access arm 2 by a rocker formed by notches 6a*6b. The dynamic center member 7 and the notches 6a and 6b on both sides thereof.
A pair of piezoelectric elements 8a, 8b that are displaced (extended 11) in opposite directions with respect to the length direction of the swing center member 7 with a distance between them.
An auxiliary actuator 9 for micro-oscillation is attached, which is configured to include both.

When this in-line head support spring mechanism 3 is used, the distance from the swing center member 7 to the magnetic head 5 is 2.
By increasing the size of the piezoelectric element 8a,
The swing range of the magnetic head 5 due to the displacement of 8b is 2×lt/
It can be expanded by a factor of 1.

Further, this sub-actuator 9 includes the pair of piezoelectric elements 8a.
, 8b are provided using the constituent members of the access arm 2, so the rigidity is relatively high, and sufficient rigidity can be obtained even with the notches 6a and 6b.Furthermore, it is lightweight, so it is easy to use during the access operation. There is no burden on the main actuator l.

Therefore, after accessing all the magnetic disks 5 on the plurality of magnetic disks 4 simultaneously in the coarse mode by the main actuator 1, each of the magnetic disks 5
A fine mode in which the pair of piezoelectric elements 8a and 8b in the sub actuator 9 are further independently displaced in opposite directions to slightly swing the swinging center member 7 from side to side allows tracking control to the target track, or Since off-track of the magnetic head 5 due to thermal deformation or the like can be easily corrected, highly accurate positioning and high-speed access are easily possible.

Note that the piezoelectric element constituting the sub-actuator described in the above embodiments is not particularly limited as long as its rigidity is not impaired and is small and lightweight; however, a laminated piezoelectric element that can be driven with a low applied voltage may be used. It is preferable to apply

FIG. 2 is a perspective view of main parts showing another embodiment of the sub actuator in the head positioning mechanism according to the present invention, and the same parts as in FIG. 1 are given the same reference numerals. The difference between the embodiment shown in this figure and the example shown in FIG. 1 is that the sub actuator 11
As shown in the figure, cutouts 12.
13 is provided to reduce the moment acting on the sub actuator 11 during rocking and increase durability.

With this configuration of the embodiment, the same effects as in the embodiment shown in FIG. 1 can be obtained.

Further, FIG. 3 is a perspective view of main parts showing still another embodiment of the sub actuator in the head positioning mechanism according to the present invention, and the same parts as in FIG. 1 are given the same reference numerals. The embodiment shown in this figure differs from the example shown in FIG.
The swinging center member 22 provided via the opening 25b has a shape in which the access arm 2 side is separated, and the separated end is connected to the access arm 2 by a screw 26. By tightening the cough screw 26, the pair of swinging center members 22 are separated. Laminated piezoelectric element 23
．． 24 with an appropriate compressive force applied thereto to improve its durability.

With this configuration of the embodiment, the same effects as in the embodiment shown in FIG. 1 can be obtained.

Further, the present invention can also be applied to a disk device using an optical head.

〔Effect of the invention〕

As is clear from the above description, the head positioning mechanism according to the present invention has a main actuator that accesses in the coarse mode, a small, lightweight, and rigid structure that swings in the fine mode between the access arm and the inline support spring. By configuring a two-stage actuator with a high sub-actuator installed, excellent advantages can be exhibited, such as making it possible to realize highly accurate positioning and high-speed access to a magnetic disk with a high track density.

[Brief explanation of the drawing]

FIG. 1 is a perspective view for explaining one embodiment of the head positioning mechanism according to the present invention; FIG. 2 is a perspective view of main parts showing another embodiment of the sub actuator in the head positioning mechanism according to the present invention; FIG. 3 is a perspective view of a main part showing still another embodiment of the sub actuator in the head positioning mechanism according to the present invention. 1 to 3, 1 is the main actuator, 2 is the access arm, 3 is the head support spring mechanism, 4 is the magnetic disk, 5 is the magnetic head,
6a, 6b, 12a12b, 25a, 25b are notches, 7.22 is a swing center member, 8a, 8b are piezoelectric elements, 9, 11.21 are sub actuators, 23.24 is a laminated piezoelectric element, 26 is a screw are shown respectively. This invention i-mad~V^徨] Gai-kei 9 search <ts4 call 71 Figure 1
Figure, l[] Marihata Ria λ sho; Eta Mekan Beishi Sous → Chij Alarm Leopard Shita Voice Fne F5 Ko Diagram Diagram

Claims (1)

[Claims] Actuator (1) in the radial direction of the recording disk (4)
A head positioning mechanism in which a head (5) is supported via an in-line head support spring mechanism (3) on an access arm (2) that is swung by the access arm (2) and the head support spring mechanism. (3) and the piezoelectric element (
8a, 8b) are connected by a micro-oscillation actuator (9) mainly, and the head support spring mechanism (3) can be independently oscillated in the radial direction of the disk (4). Positioning mechanism.