JPH04355654A - Voice coil motor - Google Patents

Abstract

PURPOSE:To improve the construction and performance of a voice coil motor. CONSTITUTION:An outer yoke 22 to which permanent magnets 20 and 21 are fixed, an inner yoke 24 which faces the permanent magnets 20 and 21 with a gap and fixed to the surface of a carrier 7 opposite to the side of the carrier 7 on which the carrier 7 holds a magnetic head 3 while it rotates and a movable coil 25 which is inserted into a gap 23 between the permanent magnets 20 and 21 and the inner yoke 26, fixed to the inner yoke side and has an interaction with a magnetic field formed by the permanent magnets 20 and 21, the outer yoke 22 and the inner yoke 24 to move to a direction perpendicular to a flux are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention 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.

[0002] For this reason, voice coil motors are also required to have rationalized structures and improved performance.

0003

2. Description of the Related Art As shown in a plan view of FIG. 3 and a side view of FIG.
This is to record information in a donut-shaped area several tens of micrometers wide called a track on the surface of the disk, and to read the recorded information.

[0004] 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. 4, and are rotated at high speed by a rotating mechanism (spindle) 4.

[0005] The magnetic head 3 is arranged in the direction of arrow A-B with the shaft 6 as the center.
The carriage 7 is held by a carriage 7 that rotates (seeks) as shown in FIG.
oiceCoil Moter) 5.

As shown in the plan view of FIG. 5 and the side view of FIG. 6, the rotary voice coil motor 5 to which the present invention is applied includes an outer yoke 8 and permanent magnets 9 and 10 fixed to the outer yoke 8. , an inner yoke 12 facing the permanent magnets 9 and 10 through an arc-shaped gap 11, and an inner yoke 12 that is inserted in the gap 11 and acts on the magnetic field of the permanent magnets 9 and 10, as shown by the arrow C-D.
It consists of a frame-shaped moving coil 13 that rotates in a direction perpendicular to the magnetic flux.

The movable coil 13 is supported by wings 7a and 7b that protrude upward and downward from the carriage 7, as shown in FIGS. 4 and 6. Therefore, moving coil 13
By energizing, the movable coil 13 moves in a predetermined direction within the gap, applies rotational force to the carriage 7, and seeks the magnetic head 3 to a predetermined position.

The carriage 7 has a pipe-shaped outer shaft 14,
A bearing 15 fixed with its center aligned with the outer shaft 14
and a shaft inserted into the bearing 15 (hereinafter referred to as the inner shaft)
The outer shaft 14 has a plurality of arms 16 protruding from the body in multiple stages, and the ends of the arms 16 are provided with an assembly of magnetic heads 3 for recording/reproducing and information reproducing.

The outer diameter of the inner shaft 6 is equal to the inner ring 15 of the bearing 15.
It is formed slightly thinner than a, and is designed to fit loosely. Therefore, the inner shaft 6 inserted into the bearing 15 is pressed by the pressurizing mechanism 17 so that the outer circumferential surface of the inner shaft 6 is
must be pressed.

The pressurizing mechanism 17 is comprised of a pin 18 embedded in the inner shaft 6 and a spring 19 that urges the pin 18 to protrude from the inner shaft 6, as shown in the sectional view of FIG. Assembly is performed by pushing the inner shaft 6 against the bias of the protruding pin 18 and inserting it into the inner ring 15a of the bearing 15.

Since the permanent magnets 9 and 10 are arranged only in the outer yoke 8, their thickness is increased to improve the magnetic characteristics of the entire magnetic circuit.

0012

[Problems to be Solved by the Invention] In the voice coil motor having the above configuration, the rigidity of the moving coil is low, and the main resonance frequency of the entire actuator including the carriage cannot be maintained high, making it difficult to position the magnetic head with high precision. The problem was that it was difficult.

Furthermore, since the moving coil is disposed in a gap, that is, in the air, it is difficult to radiate heat, and the thermal resistance is large, which limits the allowable current input to the moving coil. Furthermore, since the gap between the movable parts such as the carriage and the movable coil and the fixed part such as the voice coil motor must be controlled, there is a problem in that it is difficult to miniaturize the apparatus.

The present invention aims at streamlining the structure and improving performance.

[0015]

[Means for solving the problem] In the present invention, FIG.
As shown in the top view of FIG. 2 and the side view of FIG.
An outer yoke 22 to which 21 is fixed, and permanent magnets 20 and 21
An inner yoke 24 is fixed to the surface opposite to the magnetic head holding surface of the carriage 7 which rotates while holding the magnetic head 3, and the gap 23 between the permanent magnets 20, 21 and the inner yoke 24. A movable coil 25 that is inserted into and fixed to the inner yoke 24 side, acts on the magnetic field formed by the magnets 20, 21, the outer yoke 22, and the inner yoke 24, and moves in a direction perpendicular to the magnetic flux. It is.

The radius of rotation of the inner yoke 24 to which the movable coil 25 is fixed is such that the center of gravity of the entire actuator system including the carriage 7 coincides with the center of rotation.

[0017]

[Operation] Since the carriage, inner yoke and moving coil are integrated, the rigidity is improved and the thermal resistance of the moving coil is reduced due to heat conduction.

[0018] Furthermore, since the number of gaps is reduced, miniaturization becomes possible. Then, by setting the radius of rotation of the inner yoke to a value that makes the center of gravity of the entire actuator coincide with the center of rotation,
Rotation becomes smooth and energy is not wasted.

[0019]

[Example] The voice coil motor according to the present invention is shown in Fig. 1.
As shown in the plan view of FIG. 2 and the side view of FIG.
0 and 21 with a gap 23 in between, and an inner yoke 24 fixed to the surface opposite to the magnetic head holding surface of the carriage 7 by adhesives, screws, etc.; A movable coil 25 is inserted and fixed to the inner yoke 24 side with adhesive or the like, and acts on the magnetic field formed by the permanent magnets 20, 21, the outer yoke 22, and the inner yoke 24, and moves in a direction perpendicular to the magnetic flux. It consists of

In this way, the carriage 7 and the inner yoke 24
Since the movable coil 25 and the movable coil 25 are integrated, the wings and the like of the prior art are not required, and the rigidity of the entire voice coil motor including the movable coil 25 is improved.

Furthermore, the heat of the moving coil 25 is transferred to the inner yoke 2.
4 to the carriage 7 due to heat conduction, the thermal resistance is reduced, and the allowable current input can be increased.

[0022] Also, since the number of gaps is reduced compared to the prior art, miniaturization is also possible. On the other hand, the moving coil 25
Since the inner yoke 24 to which the magnetic head 3 is fixed is made of a magnetic material, its specific gravity is higher than that of the carriage 7 made of aluminum alloy or magnesium alloy. By determining the optimum radii in opposite directions for the head 3 and the arm 16 that supports it, it is possible to align the center of gravity of the entire actuator system with the center of rotation.

[0023] Accordingly, the rotation of the actuator becomes smooth and waste of energy can be avoided. Furthermore,
The entire carriage 7 is attracted by the magnetic field formed by the permanent magnets 20 and 21, the outer yoke 22, and the inner yoke 24, and the inner ring 15a surface of the bearing 15 and the inner shaft 6 are in close contact with each other. The pressure mechanism 17 becomes unnecessary.

In FIG. 1, 26 projecting from both ends of the outer yoke 22 in the direction of the carriage 7 are yokes for forming a side magnetic field.

[0025]

According to the present invention, the rigidity of the voice coil motor can be improved, the main resonance frequency of the entire actuator can be increased, and the magnetic head can be positioned with high precision.

Furthermore, since the allowable current input to the moving coil can be increased, the actuator can move at high speed. Furthermore, since the only gap to be managed is between the moving coil and the permanent magnet, the overall size can be reduced.

Furthermore, since the inner shaft is magnetically attracted to the inner ring of the bearing, there is no need for a pressurization mechanism, resulting in great economical and industrial effects.

[Brief explanation of drawings]

[Fig. 1] Plan view of the voice coil motor of the present invention,

[
Figure 2] Side view of Figure 1;

FIG. 3 is a plan view of a magnetic disk device to which the present invention is applied;

[Figure 4] Side view of Figure 3,

[Figure 5] Plan view of a conventional voice coil motor,

[Fig. 6] Side view of Fig. 5,

[Figure 7] Cross-sectional view of the pressurization mechanism,

[Explanation of symbols]

3 Magnetic head, 6 Inner shaft, 7 Carriage, 15 Bearing, 15a Inner ring, 17 Pressurization mechanism, 20, 21 Permanent magnet, 22 Outer yoke, 23 Gap, 24 Inner yoke, 25 Moving coil, 26 Yoke,

Claims (2)

[Claims] Claim 1: An outer yoke (22) to which permanent magnets (20, 21) are fixed;
) across a gap (23), and the magnetic head (3)
an inner yoke (24) fixed to the surface opposite to the magnetic head holding surface of the carriage (7) which rotates while holding the permanent magnets (20, 21) and the inner yoke (24).
) is inserted into the gap (23) of the inner yoke (2
A movable coil (25) is fixed on the side 4) and moves in a direction perpendicular to the magnetic flux by acting on the magnetic field formed by the permanent magnets (20, 21), the outer yoke (22), and the inner yoke (24). ) A voice coil motor comprising: 2. The radius of rotation of the inner yoke (24) to which the moving coil (25) of claim 1 is fixed is the same as that of the carriage (7).
) A voice coil motor characterized in that the center of gravity of the entire actuator system including the actuator has a value that coincides with the center of rotation.