JPH03183350A - Voice coil motor - Google Patents

Abstract

PURPOSE:To level the force constants of a motor by dividing the permanet magnets inside and outside the space, in which the coil of a voice coil motor rocks, and parallel magnetizing them so that the magnetic fluxes may be perpendicular to the shifting direction of a coil and the effective current direction. CONSTITUTION:A magnetic head 3 for seeking is mounted to one end of a carriage 7, which rocks around a rotary shaft 6, and a coil 14, which drives the carriage 7, is mounted at the other end. The coil 14 rocks as an arrow C-D between inner permanent magnets 15 and 16 and outer permanent magnets 17 and 18. The permanent magnets 15-18 are divided into each plural magnets 15a, 15b-18a, and 18b. Those are magneized parallel so that they may be perpendicular to the shifting direction M of the coil and the effective flow direction m, whereby the force constants between the coil 14 and the permanent magnets 15-18 at the time of a magnetic head 3 seeks the outermost track and the innermost track are levelled. Hereby, the seeking of the magnetic head 3 is stabilized, and magnetization expenditure is reduced.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of a rotary type voice coil motor, the purpose of this invention is to average the force constant of the voice coil motor, thereby smoothing its operation and the seeking of the magnetic head. An arc-shaped outer permanent magnet faces the arc-shaped inner permanent magnet through an arc-shaped gap, and a coil is inserted in the gap to act on the magnetic field of the permanent magnet and rotate in a direction perpendicular to the magnetic flux. In a voice coil motor consisting of a voice coil motor, the inner permanent magnet and the outer permanent magnet are divided, and when the magnetic head is located at the innermost and outermost cylinders of the magnetic disk, They are each configured to be magnetized in parallel so that the magnetic flux is in the right angle direction.

[Industrial application field]

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

In recent years, magnetic disk drives are becoming more accurate as recording density increases.

For this reason, it is desired that, for example, the seek of the magnetic head be performed stably.

[Conventional technology]

As shown in the plan view of FIG. 4 and the side view of FIG. It is used to record information in a so-called donut-shaped area with a width of several tens of micrometers, and to read the recorded information.

The tracks are arranged concentrically on the surface of the magnetic disk 2 like the annual rings of a tree, and one track is an area in which one magnetic head 3 can continuously write/read.

The magnetic disks 2 are stacked on one axis at equal intervals as shown in FIG. 5, and are rotated at high speed by a rotating mechanism (spindle) 4.

The magnetic head 3 rotates (
The carriage 7 is, for example, a rotary voice coil motor (VCM).
It is rotated by Voice Co11 Moter) 5.

As shown in the plan views of FIGS. 5 and 6, the rotary voice coil motor 5 includes an inner yoke 8, an arcuate inner permanent magnet 9.10 fixed to the inner yoke 8, and an inner permanent magnet 9.10 fixed to the inner yoke 8. An arcuate outer permanent magnet 11.12 faces the side permanent magnet 9.10 through an arcuate gap G, an outer yoke 13 to which the outer permanent magnet 11.12 is fixed, and It consists of a frame-shaped coil 14 that is inserted and acts on the magnetic field of a permanent magnet and rotates in a direction perpendicular to the magnetic flux as shown by arrow C-D.

This coil 14 is supported by arms 7a and 7b that project upward and downward from the carriage 7, as shown in FIG.

Therefore, by energizing the coil 14, the coil 14 acts on the magnetic flux and moves in a circular arc in a predetermined direction within the gap, applying rotational force to the carriage 7 and seeking the magnetic head 3.

[Problem to be solved by the invention]

By energizing as described above, the coil moves in an arc shape within the gap by acting on the magnetic flux of the inner and outer permanent magnets magnetized in an arc shape.

However, due to its nature, the distribution of magnetic flux density of a permanent magnet is large in the center and decreases as it approaches the ends, which appears as a drop in the force constant of the voice coil motor.

For this reason, there is a problem in that the seek operation is faster at the center of the permanent magnet and becomes slower as it moves toward the ends, causing disturbances such as vibrations in the seek of the magnetic head, which is ideal for constant speed.

The present invention averages the force constant of the voice coil motor,
The purpose of this operation is to smooth out the seek operation of the magnetic head.

[Means to solve the problem]

In the present invention, as shown in the plan view of FIG. 1, the inner permanent magnets 15, I6 and the outer permanent magnets 17.
18 are divided in the circumferential direction at the center, so that when the magnetic head is located at the innermost and outermost cylinders of the magnetic disk, the magnetic flux is perpendicular to the moving direction of the coil 14 and the effective current direction. They are each magnetized in parallel.

[Effect]

By dividing the permanent magnet at the center where the magnetic flux density is highest, when the magnetic head is in the cylinder near the center of the magnetic disk, the theta direction and the direction of force generation in the coil do not match and shift, making it difficult to drive the carriage. The component force that becomes force becomes smaller.

Therefore, the force constant of the voice coil motor at the center of the permanent magnet is suppressed, and the magnetic flux density is averaged in a pseudo manner by correcting the droop.

〔Example〕 1 to 3 show an embodiment of the present invention.

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

In the present invention, as shown in the plan view of FIG. 1, the inner permanent magnets 15, I6 and the outer permanent magnets 17.
18 is divided in the circumferential direction at the center as 15a, 15b, 16a, 16b and 17a, 17b, 18a, 18b, respectively, and the magnetic head 3 shown in FIG. cylinder(
When the coil 14 is positioned on the track) as shown in FIG.
They are each magnetized in parallel so that the magnetic flux is perpendicular to the moving direction of the magnetic flux and the effective current direction acting on the magnetic flux.

By doing so, the permanent magnet is divided at the central part where the magnetic flux density is highest, and the magnetic flux density in this part is reduced, and when the print head is in the cylinder near the center of the magnetic disk (the coil 14 is (when in such a position),
Since the theta direction (rotation direction of the coil 14) arrow M and the arrow m in the direction in which force is generated on the coil 14 do not coincide with each other, they deviate from each other, resulting in a phenomenon in which the component force serving as the driving force for the carriage becomes smaller.

For this reason, the force constant of the rotary voice coil motor at the center of the permanent magnet is suppressed, and as shown by the solid line in the table of Figure 3, the magnetic flux density is averaged in a pseudo manner by correcting the droop, which improves the seek performance. The operating speed will be constant and smooth.

The plan view of FIG. 2 shows an embodiment in which the present invention is applied to a rotary voice coil motor having an E-type yoke 19.

In this embodiment as well, the inner permanent magnet 20 and the outer permanent magnet 21 are divided in the circumferential direction at the center, and the magnetic head 3 is attached to the innermost and outermost cylinders of the magnetic disk as in FIG. When the coil 22 is positioned at the position shown in FIG. play.

〔Effect of the invention〕

According to the present invention, the force constant of the voice coil motor is averaged, and seek of the magnetic head is stabilized.

In addition, parallel magnetization is better than arc-shaped magnetization in the prior art, resulting in lower costs, which has great economical and industrial effects.

[Brief explanation of drawings]

FIG. 1 is a plan view of the voice coil motor of the present invention, FIG. 2 is a plan view showing another embodiment of the present invention, FIG. 3 is a chart showing the magnetic flux distribution of the permanent magnet according to the present invention, and FIG. 4 5 is a side view of FIG. 4, and FIG. 6 is a plan view of a conventional rotary voice coil motor. In the figure, 3 is a magnetic head, 5 is a rotary voice coil motor, 7 is a carriage, 8 is an inner yoke, 9.1O115,1
6, 20 are inner permanent magnets, 11, 12.17.1
8.21 is an outer permanent magnet, 13 is an outer yoke, 14.22 is a coil, and 19 is an E-type yoke. S% Akira's voice car I motor, Kikuyo No. 1

Claims (1)

[Scope of Claims] An arc-shaped inner permanent magnet (15, 16), and an arc-shaped outer permanent magnet (17, 18)
and a coil (14) that is inserted in the gap and acts on the magnetic field of the permanent magnet and rotates in a direction perpendicular to the magnetic flux, the inner permanent magnet (15, 16) ) and the outer permanent magnets (17, 18), respectively, and when the magnetic head is located at the innermost and outermost cylinders of the magnetic disk, the magnetic head is perpendicular to the moving direction of the coil (14) and the effective current direction. A voice coil motor characterized in that each coil is magnetized in parallel so that the magnetic flux is oriented in the same direction.