JPH03135354A - Voice coil motor - Google Patents

Abstract

PURPOSE:To prevent the averaging of flux density of a permanent magnet as well as the deterioration of flux due to the temperature-rise of the same by a method wherein a flux canceling through hole is bored on a permanent magnet while a ventilating through hole, communicated with the flux canceling through hole, is bored on a yoke. CONSTITUTION:Permanent magnets 15a-15d, constituting a voice coil motor, are provided with one set of flux canceling through hole 16, averaging the flux and bored on respective magnets. Further, yokes 14a, 14b are provided with a ventilating through hole 17, communicated with the flux canceling through hole 16 for preventing the temperature rise of the permanent magnets 15a-15d due to a coil 12. The flux canceling through hole 16 is formed so as to have an oblong shape along the direction of the movement from the central parts of the permanent magnets 15a-15d toward the end thereof as shown in a diagram. According to this method, the flux density of the permanent magnet at the hole is reduced and the flux density of the permanent magnet may be averaged as a whole. Further, ventilation is improved by the ventilating through holes whereby the temperature rise of the permanent magnets may be suppressed and the deterioration of the flux may be prevented.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of the voice coil motor, it is possible to average the distribution of magnetic flux density of the permanent magnets, and to extend the operation of the moving element by preventing a decrease in the magnetic flux due to a rise in the temperature of the permanent magnets. The purpose of this is to smooth the seek of the magnetic head, and it has a plurality of permanent magnets facing each other with a gap between them, and a coil inserted into the gap that swings in the right angle direction by acting on the magnetic field of the permanent magnets. In a voice coil motor consisting of a moving element, each of the permanent magnets is provided with at least one magnetic flux attenuation through hole for averaging the magnetic flux, and the yoke is provided with a ventilation through hole communicating with the magnetic flux attenuation through hole. Configure by drilling holes.

[Industrial application field]

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

[Prior Art] As shown in the plan view of FIG. 2, a magnetic disk device 1 to which the present invention is applied has a donut-shaped area called a track on the surface of a magnetic disk 2, which is a recording medium, and has a width of several tens of μm. It is used to record information.

The tracks are arranged concentrically on the surface of the recording medium like the rings of a tree, and one track is an area in which one magnetic disk 3 can continuously write/read.

The air head 3 is attached to a carriage 7 via a gimbal 4, and the carriage 7 is equipped with a voice coil motor (Voic
e Co11 Moter) 5 rotates (seeks) around the fulcrum 6 as shown by the arrow A-B.

8 is a base that supports all of these.

The voice coil motor 5 is supported by two upper and lower yokes 9a and 9b, respectively, as shown in the plan view of FIG. 3(a) and the cross-sectional view taken along line CD in FIG. Gap arrow G
A plurality of permanent magnets 10a to 10d are movably inserted into the gap, and the permanent magnets 10a to 10d are opposed to each other.
The moving element 13 has a coil 12 that acts on the magnetic field d.

The mover 13 is connected to the carriage 7, and when the coil 12 is energized, the mover 13 moves in a predetermined direction within the gap, applying rotational force to the carriage 7 and causing the magnetic head 3 to seek.

[Problem to be solved by the invention]

The voice coil motor is configured to act on the magnetic field of the permanent magnets and move within a gap where the permanent magnets face each other by energizing the coil of the mover.

However, the distribution of magnetic flux density in a permanent magnet is large in the center of the magnet and decreases as it approaches the periphery.

For this reason, the motion of the mover is faster at the center of the permanent magnet and slower at the ends, resulting in problems such as vibrations and other disturbances in the seek of the magnetic head, which should ideally have a constant speed.

Further, there is a problem in that the temperature of the permanent magnet increases due to the heat generated by the coil due to continuous seeking, causing a decrease in magnetic flux and having an adverse effect on seeking.

The purpose of the present invention is to average the distribution of magnetic flux density of the permanent magnet and to prevent the magnetic flux from decreasing due to the temperature rise of the permanent magnet, thereby smoothing the movement of the slider and the seeking of the magnetic head. It is something to do.

[Means to solve the problem]

In the present invention, as shown in the perspective view of FIG. 1(a),
At least one through hole 16 for reducing magnetic flux is formed in each of the permanent magnets 15a to 15d to average the magnetic flux, and a through hole 17 for ventilation that communicates with the through hole 16 for reducing magnetic flux is formed in the yokes 14a and 14b. It was established.

[Effect]

By providing the through holes for reducing magnetic flux, the magnetic flux density in the holes of the permanent magnet is reduced and averaged out as a whole.

In addition, by providing a ventilation through hole in the yoke that communicates with the magnetic flux reduction through hole, ventilation is improved, which suppresses the temperature rise of the permanent magnet and prevents a reduction in magnetic flux. Stabilize.

〔Example〕

FIG. 1 shows an embodiment of the present invention.

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

In the present invention, the perspective view of FIG. 1(a) and the perspective view of FIG. 1(b)
As shown in the plan view of FIG.
and a plurality of permanent magnets 15a to 15d opposed to each other with a gap between them, supported by the magnets 14b and 14b, and a moving element 13 having a coil 12 inserted into the gap and moved in a right angle direction by acting on the magnetic field of the permanent magnets 15a to 15d. This is a voice coil motor comprising permanent magnets 15a to 15d, each of which is provided with at least one magnetic flux reduction through hole 16 for averaging the magnetic flux thereof.

Further, the yokes L4a, 14b are provided with ventilation through-holes 17 that communicate with magnetic flux attenuation through-holes 16 for preventing the temperature rise of the permanent magnets 15a to 15d due to the coil element 2.

The magnetic flux attenuation through hole 16 is shaped like an ellipse in the moving direction from the center to the end of the permanent magnets 15a to 15d, as shown, so that the magnetic flux in the moving direction of the mover 13 is averaged.

Therefore, the ventilation through-hole 17 that communicates with the magnetic flux attenuation through-hole 16 also has an oval shape.

Although it has been explained that only one oval-shaped through hole is provided for one permanent magnet, the above-mentioned through hole is not limited to this.
For example, a plurality of circular holes having different diameters may be arranged in a row in the moving direction of the mover.

The changes in the magnetic flux density of the permanent magnets 15a to 15d in the present invention are such that the central part is flattened with respect to both ends, as shown by the solid line, compared to the conventional technology shown by the dotted line in FIG. I understand.

Further, in the above description, the permanent magnets 15 are attached to the yokes 14a and 14b.
This was done by providing a through hole 17 for ventilation that communicates with the through hole 16 for reducing magnetic flux a to 1.5d, but the permanent magnet 15a to
It goes without saying that the magnetic flux reduction through hole 16 15d alone is also effective.

[Effects of the Invention] According to the present invention, the magnetic flux density of the permanent magnet is averaged as a whole, the temperature rise of the permanent magnet is suppressed, a decrease in magnetic flux can be prevented, and the seek of the magnetic head is stabilized. , it has great economic and industrial effects.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view showing the main parts of the voice coil motor of the present invention, FIG. 1(b) is a plan view of the voice coil motor of the present invention, and FIG. 1(C) is the same figure (b). E-F sectional view of Figure 1 (d
) is a diagram showing changes in magnetic flux density of a permanent magnet according to the present invention, FIG. 2 is a plan view of a magnetic disk device to which the present invention is applied, FIG. 3(a) is a plan view of a conventional voice coil motor, FIG. 3(b) is a sectional view taken along line CD in FIG. 3(a). In the figure, l is a magnetic disk device, 2 is a magnetic disk, 3 is a magnetic head, 5 is a voice coil motor, 6 is a fulcrum,
7 is a carriage, 9a, 9b, 14a,
14b is a yoke, 10a to 10d, 15a
-15d is a permanent magnet, 12 is a coil, 1
3 is a moving element, 16 is a through hole for reducing magnetic flux, and 17 is a through hole for ventilation. Diagram showing the change Σ of the magnetic flux of a permanent magnet by 7 degrees due to Mokuhanaki (d) Figure 1 (Part 2)

Claims (1)

[Scope of Claims] A plurality of permanent magnets (15a to 15d) each supported by a yoke (14a, 14b) and facing each other with a gap therebetween; In a voice coil motor comprising a mover having a coil that acts and swings in a right angle direction, each of the permanent magnets (15a to 15d) has at least one magnetic flux reduction through-hole for averaging the magnetic flux thereof. A voice coil motor, characterized in that a hole (16) is formed, and a ventilation through hole (17) is formed in the yoke (14a, 14b) to communicate with the magnetic flux reduction through hole (16).