JPH0778426A - Yoke structure for voice coil motor - Google Patents

Abstract

PURPOSE:To provide a yoke structure for a voice coil motor allowing reduction of the cost of manufacturing a magnetic circuit. CONSTITUTION:The voice coil motor is constituted of an upper yoke 8 fixed with a permanent magnet 7 and a coil 6 positioned between it and a lower yoke 9. The upper yoke 8 is provided with side yokes 8a integral with the yoke 8 on both of its ends and excitation is operated between this upper yoke 8 and the lower yoke 9. Further, their connection is made in such a way that a projecting part 11 set on the lower tip of the side yoke 8a of the upper yoke 8 is inserted into a hole part 12 set on a position opposed to the lower yoke 9 and held by a magnetic force generated between the upper yoke 8 and the lower yoke 9. Further, it is effective in that the upper yoke 8 is formed in an inverse U shape using a thin plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor for driving a magnetic head used in a fixed magnetic disk device, and more particularly to a yoke structure of the voice coil motor.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. Figure 3
FIG. 3A is a plan view of a fixed magnetic disk device according to a conventional example, and FIG. 3B is a cross-sectional view taken along line BB of the fixed magnetic disk device according to the conventional example. Magnetic disk 1
Is rotated by a spindle motor 3 fixed to a base 2, and data is read and written by a magnetic head 4.
The magnetic head 4 is fixed to one end of a carriage 5 which is rotatably supported by the base 2, and a coil 6 is fixed to the other end of the carriage 5. The permanent magnet 7 and the lower yoke 2 of the magnetic circuit 24 constituted by the partial yoke 22 and the lower yoke 23.
A voice coil motor is constructed by combining the coil 6 so that the coil 6 is positioned between the coil 6 and the coil 6.
By the current control of (1), the coil 6 is rotated based on Fleming's law, and the magnetic head 4 is moved and positioned at high speed accordingly. The magnetic circuit 24 is composed of parts of an upper yoke 21, a side yoke 22 and a lower yoke 23, which are fixed by screws 25, respectively, and are fixed to the base 2 by three screws (not shown).

[0003]

According to the above-mentioned method, the magnetic circuit is composed of the upper yoke, the side yoke and the lower yoke, which are fixed by screws, respectively, so that the number of parts is large and the number of assembling steps is also large. This causes a problem that the manufacturing cost is high. The present invention has been made in view of the above problems, and an object thereof is to provide a yoke structure for a voice coil motor that reduces the manufacturing cost of a magnetic circuit.

[0004]

According to the present invention, a voice coil motor has a coil positioned between an upper yoke and a lower yoke to which a permanent magnet is fixed, and the upper yoke has upper and lower ends at both ends thereof. This is accomplished by having a side yoke that is integral with the yoke. Further, a protrusion is provided on the lower end of the side yoke of the upper yoke, and the protrusion is inserted into a hole provided at a position facing the lower yoke so that the upper yoke and the lower yoke are held by the magnetic force generated therebetween. Is good.

Further, it is effective to form the upper yoke into an inverted U shape by using a thin plate.

[0006]

According to the structure of the present invention, since the upper yoke has the side yokes integrated with the upper yoke at both ends thereof,
The two side yokes that were used in the past are no longer necessary, and the number of parts can be reduced. Further, a protrusion provided at the lower end of the side yoke of the upper yoke is inserted into a hole provided at a position facing the lower yoke so that the upper yoke and the lower yoke are held and connected by a magnetic force generated therebetween. For this reason, what is conventionally fixed by using a screw or the like can be connected by fitting, and the screw is not required, and at the same time, the number of assembling steps is reduced, and the female thread processing for the side yoke in the conventional example is also unnecessary. Furthermore, since the upper yoke is formed in an inverted U shape using a thin plate, it can be manufactured in one step by press working, and the number of parts processing man-hours is also reduced.

[0007]

EXAMPLE An example will be described with reference to FIGS.
FIG. 1A is a plan view of a fixed magnetic disk device in the embodiment, FIG. 1B is a sectional view taken along the line AA of the fixed magnetic disk device in the embodiment, and FIG. 2 is a fixed magnetic disk device in the embodiment. FIG. 3 is an explanatory diagram of the magnetic circuit assembly of FIG. The same components as those in the conventional example are designated by the same reference numerals. The magnetic disk 1 is rotated by a spindle motor 3 fixed to a base 2, and the magnetic head 4 reads and writes data. The magnetic head 4 is fixed to one end of a carriage 5 rotatably supported by the base 2, and a coil 6 is fixed to the other end of the carriage 5, and an inverted U-shape (or a permanent magnet 7 and a magnetic material) is formed. A voice coil motor is constructed by combining the permanent magnet 7 and the lower yoke 9 of the magnetic circuit 10 composed of the upper yoke 8 and the lower yoke 9 in a U-shape so that the coil 6 is located. By controlling the current of the coil 6, the coil 6 is rotated based on Fleming's law, and the magnetic head 4 is moved and positioned at high speed accordingly.

In the present invention, as shown in FIG. 2, the protrusion 11 provided at the lower end of the side yoke 8a of the upper yoke 8 is inserted into the hole 12 provided at the position opposite to the lower yoke 9,
The magnetic force 13 generated between the upper yoke 8 and the lower yoke 9 keeps the balance in good balance. In FIG. 1B, the hole 12 is exaggerated and enlarged, but the clearance between the hole 12 and the protrusion 11 is about 0.1 to 0.2 mm.

Although the projection 11 is rectangular in this embodiment, it may have any shape as long as it can be positioned. Further, the polarity of the permanent magnet 7 may be the N pole on the left side and the S pole on the right side in FIG.

[0010]

According to the present invention, the upper yoke has the side yokes integrated with the upper yoke at both ends thereof.
The manufacturing cost can be reduced by eliminating the need for two side yokes that have been used in the past. Further, the upper yoke and the lower yoke are connected by inserting a protrusion provided at the lower end of the side yoke of the upper yoke into a hole provided at a position facing the lower yoke, thereby generating the upper yoke and the lower yoke therebetween. Since it is held by magnetic force and connected, what used to be fixed using screws etc. can be connected by fitting, screwing is unnecessary and assembly man-hours are reduced, and female thread processing for side yoke in conventional example Becomes unnecessary and the manufacturing cost can be reduced. Further, since the upper yoke is formed in an inverted U shape using a thin plate, it can be manufactured in one step by press working, so that the number of man-hours for processing parts can be reduced and the manufacturing cost can be reduced.

[Brief description of drawings]

1A and 1B are configuration diagrams of this embodiment, in which FIG. 1A is a plan view of a fixed magnetic disk device, and FIG. 1B is a cross-sectional view of a magnetic circuit AA line of the fixed magnetic disk device.

FIG. 2 is an explanatory diagram of a magnetic circuit assembly of the fixed magnetic disk device in this embodiment.

3A and 3B are configuration diagrams of a conventional example, FIG. 3A is a plan view of a fixed magnetic disk device, and FIG. 3B is a cross-sectional view of a magnetic circuit BB of the fixed magnetic disk device in the conventional example.

[Explanation of symbols]

 1 magnetic disk 2 base 3 spindle motor 4 magnetic head 5 carriage 6 coil 7 permanent magnet 8 upper yoke 8a side yoke 9 lower yoke 10 magnetic circuit 11 protrusion 12 hole 13 magnetic force 21 upper yoke 22 side yoke 23 lower yoke 24 Magnetic circuit 25 fixing screw

Claims (3)

[Claims] 1. A voice coil motor for driving a magnetic head used in a fixed magnetic disk device, comprising a coil positioned between an upper yoke and a lower yoke to which permanent magnets are fixed, the upper yoke being provided at both ends thereof. A yoke structure for a voice coil motor having side yokes integrated with an upper yoke. 2. The yoke structure according to claim 1, wherein a protrusion is provided at a lower end of a side yoke of the upper yoke, and the protrusion is inserted into a hole provided at a position facing the lower yoke, and the upper yoke and the lower yoke are connected to each other. A yoke structure for a voice coil motor, which is held by the magnetic force generated between them. 3. The yoke structure for a voice coil motor according to claim 1, wherein the upper yoke is formed in a reverse U shape by using a thin plate.