JPH03178546A - Voice coil motor - Google Patents

Abstract

PURPOSE:To reduce a leakage magnetic flux which affects adverse influence to a magnetic disk without increasing in size by providing a magnetic shielding member at any one or the other of first and second yokes through a nonmagnetic member. CONSTITUTION:A nonmagnetic member 13 made of an aluminum plate or the like is adhered to the outside of an inner yoke 8 which affects adverse influence of a leakage magnetic flux to a magnetic disk, and a magnetic shielding member 14 having large permeability such as a permalloy plate or the like is adhered thereto. Thus, the magnetic flux leaked from the yoke 8 is shielded by the member 14 provided to be magnetically insulated to largely reduce the leakage magnetic flux, thereby remarkably reducing the influence to the disk.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of a voice coil motor, the purpose of this invention is to reduce leakage magnetic flux that adversely affects a magnetic disk without increasing the size of the device. A first magnet fixed to a yoke, a second magnet facing the first magnet with a gap in between, a second yoke to which the second magnet is fixed, and a first magnet inserted in the gap. In a voice coil motor consisting of a coil that acts on the magnetic field of a second magnet and moves in a direction perpendicular to the magnetic flux, a non-magnetic member is placed on the outside of one or both of the first and second yokes. A magnetic shielding member is provided therebetween.

[Industrial application field]

The present invention relates to the structure of a voice coil motor.

In recent years, magnetic disk drives have been trending towards higher recording densities and smaller sizes.

For this reason, leakage magnetic flux of the voice coil motor, for example, becomes a problem, and it is desired to reduce this without increasing the size of the device.

[Conventional technology]

A magnetic disk device l using a voice coil motor to which the present invention is applied has a number called a trunk on the surface of a magnetic disk 2, which is a recording medium, as shown in the plan view of FIG. 2 and the side view of FIG. This is for recording information in a dona-sock-shaped area with a width of 10 μm and reading the recorded information.

The trunks are arranged in concentric circles on the surface of the magnetic disk 2 like tree rings, and one track connects to one magnetic disk.
is an area that can be continuously written/read.

The magnetic disks 2 are stacked on one axis at equal intervals as shown in FIG. 3, and are rotated at high speed by a rotating mechanism (spindle) 4.

The magnetic head 3 rotates around the shaft 6 as shown by arrow A-8 (
The carriage 7 is held by, for example, a voice coil motor (VCM).
o1J Moter) 5.

As shown in the plan views of FIGS. 3 and 4, the rotary voice coil motor 5 to which the present invention is applied includes an inner yoke 8 that is a first yoke, and a first yoke fixed to the inner yoke 8. Inner side permanent magnets 9a, 9 which are magnets of
b, outer permanent magnets 10a and 10b which are second magnets facing the inner permanent magnets 9a and 9b through an arcuate gap G, and outer permanent magnet 10a,
The outer yoke 11, which is the second yoke to which the magnet 10b is fixed, is inserted in the gap G and acts on the magnetic fields of the first and second permanent magnets 9a, 9b and IOA, 10b, as shown by the arrow C.
-D, it is separated from the frame-shaped coil 12 that rotates in a direction perpendicular to the magnetic flux.

The coil 12 is supported by arms 7a and b that project upward and downward from the carriage 7, as shown in FIG.

Therefore, by energizing the coil 12, the coil 12 moves within the gap in a predetermined direction, applies rotational force to the carriage 7, and seeks the magnetic head 3.

[Problem to be solved by the invention]

In the voice coil motor having the above configuration, there is a problem that unless the leakage magnetic flux to the magnetic disk is suppressed to a certain value or less, it may cause noise during writing/reading.

For this reason, a yoke large enough to prevent magnetic flux saturation was required.

However, there is a problem in that increasing the size of the yoke increases the size of the device.

An object of the present invention is to reduce leakage magnetic flux that adversely affects a magnetic disk without increasing the size of the device.

[Means to solve the problem]

In the present invention, as shown in the plan view of FIG. In this example, a magnetic shield member 14 is provided on the outside of the inner yoke 8 with a non-magnetic member 13 interposed therebetween.

[Effect]

The magnetic flux leaked from the inner yoke is transferred to the non-magnetic member 13
It is shielded by a magnetic shield member that is magnetically insulated through the magnetic shielding member, and leakage magnetic flux is significantly reduced.

〔Example〕

FIG. 1 shows an embodiment of the present invention.

Identical parts are designated by the same reference numerals throughout the design.

In the present invention, as shown in the plan view of FIG. 1, a non-magnetic member 13 such as an aluminum plate or a synthetic resin plate is provided on the outside of the inner yoke 8 where leakage magnetic flux affects the magnetic disk. A magnetic shield member 14 having a high magnetic permeability, such as a permalloy plate, is provided thereon by adhesive or other means.

With this configuration, the magnetic flux leaking from the inner yoke 8 is shielded by the magnetic shield member 14 that is provided in a magnetically insulated manner, and the leaking magnetic flux is significantly reduced, and the influence on the magnetic disk is greatly reduced. decreases to

At this time, the magnetic shielding member 14 must not be in magnetic contact with the inner yoke 8.

If they are in contact with each other, they will become magnetically integrated with the yoke 8 and magnetic flux will leak to the outside.

The thickness of the non-magnetic member 13 and the magnetic shield member 14 may be extremely thin, and this does not result in an increase in the size of the device.

Although the above explanation has been made regarding a rotary type voice coil motor, it goes without saying that the present invention may be applied to a linear type voice coil motor.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the leakage magnetic flux that adversely affects the magnetic disk without increasing the size of the device, and it has great industrial effects.

[Brief explanation of drawings]

FIG. 3 is a side view of FIG. 2, and FIG. 4 is a plan view of a conventional voice coil motor. In the figure, 5 is a rotary voice coil motor, 7 is a carriage, 8 is a first yoke (inner side yoke), 9a, 9b
are the first magnet (inner side permanent magnet), 10a, 10b
is the second magnet (outer permanent magnet), 11 is the second yoke (outer yoke), 12 is the coil,
13 is a non-magnetic member, and 14 is a magnetic shielding member. Between the planes of the uninvented voice coil motor, Figure 1, Figure 2, Figure 2, Figure 3, Figure 1, Figure 1, Thousand plane view of the voice coil motor.

Claims (1)

[Claims] A first yoke (8) and a first magnet (9a) fixed to the first yoke (8).
, 9b), second magnets (10a, 10b) facing the first magnets (9a, 9b) through a gap, and a second yoke to which the second magnets (10a, 10b) are fixed. (11); and a coil (12) that is inserted in the gap and acts on the magnetic fields of the first and second magnets and moves in a direction perpendicular to the magnetic flux. 1 and 2
A magnetic shielding member (14) is attached to the outside of one or both of the yokes (8, 11) via a non-magnetic member (13).
) A voice coil motor characterized by being provided with.