JPH0778427A - Structure for fixing magnetic circuit of voice coil motor - Google Patents

Abstract

PURPOSE:To provide a highly reliable method of fixing the magnetic circuit by fixing the lower surface of the side yoke lower end of an upper yoke on the upper surface of a lower yoke and fixing the end surface of the projecting part of the upper yoke on the hole part end surface of the lower yoke. CONSTITUTION:The projecting part 15 of an upper yoke 8 is fitted into a hole part 16 provided on a lower yoke 9, its position is decided and the yokes 8 and 9 are held by a magnetic force applied inbetween. At this time, the yoke 8 is pressed by a stopper 20 so that the end surface 15a of the projecting part 15 is brought into contact with a hole part end surface 16a and in this condition, the stopper 20 and the yoke 9 are fixed on a base 2. Also, a buffering member 11 is fixed on the yoke 8 by adhesive agents and a cover 12 is fixed by a screw. At this time, the yoke 8 is fixed receiving a force in the direction of a magnetic force by the cover 12 via the member 11.

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 fixing structure for a voice coil motor magnetic circuit.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 5A is a plan view of a conventional fixed magnetic disk device, FIG. 5B is a sectional view taken along the line BB of the fixed magnetic disk device of FIG. 5A, and FIG. 6 is a conventional fixed magnetic disk device. It is a magnetic circuit assembly explanatory drawing of an apparatus. 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 a permanent magnet 7 and an upper yoke 8 made of a magnetic material and a lower portion. Magnetic circuit 10 composed of yoke 9
The voice coil motor is constructed by combining the permanent magnet 7 and the lower yoke 9 so that the coil 6 is positioned. The current control of the coil 6 causes the coil 6 to rotate based on Fleming's law. Accordingly, the magnetic head 4 is moved and positioned at high speed.

In the conventional magnetic circuit, as shown in FIG. 6, a protrusion 15 provided at the lower end of the side yoke 8a of the upper yoke 8 is inserted into a hole 16 provided at a position corresponding to the lower yoke 9. However, the magnetic force 17 generated between the upper yoke 8 and the lower yoke 9 maintains the balance in a good balance.

[0004]

According to the above-mentioned method, the magnetic circuit is constructed such that the protrusion provided on the lower end of the side yoke of the upper yoke is inserted into the hole provided at the corresponding position of the lower yoke, and the upper yoke is formed. Since it is held by the magnetic force generated between the lower yoke and the lower yoke, a gap is generated by the variation in the processing accuracy of the protrusion and the hole, and an impact stronger than the holding force acting between the upper yoke and the lower yoke is generated. When added, the upper yoke is displaced by the amount of the clearance, and the positional relationship between the upper yoke and the lower yoke is changed, and as a result, the magnetic characteristics of the magnetic circuit are changed. Furthermore, in the worst case, there is a possibility that the fixed magnetic disk device may break down due to the upper yoke coming off the fitting portion.

The present invention has been made in view of the above problems, and an object thereof is to provide a highly reliable method for fixing a voice coil motor magnetic circuit in which the magnetic characteristics do not change even when the magnetic circuit is impacted. Especially.

[0006]

According to the present invention, the above-mentioned object has a coil positioned between an upper yoke to which a permanent magnet is fixed and a lower yoke, and the upper yoke is integrated with the upper yoke at both ends thereof. Has a side yoke
A voice coil in which a protrusion is provided at 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. In the magnetic circuit of the motor, first fixing means for fixing the lower yoke lower surface of the side yoke of the upper yoke against the upper surface of the lower yoke,
This is achieved by including a second fixing unit that fixes the end surface of the protrusion of the upper yoke in contact with the end surface of the hole of the lower yoke.

Here, as a first fixing means, a cushioning member is sandwiched between the lower surface of the cover and the upper surface of the upper yoke of the fixed magnetic disk device to fix the magnetic disk apparatus. It is effective to fix the upper yoke and the lower yoke to the upper surface of the base of the fixed magnetic disk device via a stopper member that comes into contact with at least one side yoke side surface of the side yoke integrated with the yoke.

[0008]

According to the structure of the present invention, the first fixing means for fixing the side yoke lower end temporary surface of the upper yoke to the upper surface of the lower yoke, and the upper yoke protruding end surface contact the lower yoke hole end surface. Since it is provided with the second fixing means in contact with the lower yoke, the upper yoke is prevented from moving up and down, front and back, and left and right with respect to the lower yoke due to a strong impact. .

Specifically, in the first fixing means, since the buffer member is sandwiched between the cover lower surface and the upper yoke upper surface of the fixed magnetic disk device to fix the magnetic circuit, the upper yoke moves up and down due to the repulsive force of the buffer member. Will not move to. Further, a frictional force is generated between the cushioning member, the lower surface of the cover and the upper surface of the upper yoke, and the frictional force prevents the upper yoke from moving back and forth. Further, in the second fixing means, the upper yoke and the lower yoke are fixed via a stopper member that abuts at least one side yoke side surface of the side yoke integrated with the upper yoke at both ends of the upper yoke. Since it was fixed to the upper surface of the base of the above, it is fixed biased to the left or right by the gap, so there is no gap,
The upper yoke does not move left or right. Furthermore, since the end surface of the lower yoke hole and the end surface of the upper yoke protrusion contact each other,
It is also effective to prevent the upper yoke from moving back and forth due to the frictional force generated during this period.

[0010]

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 a magnetic circuit assembly diagram of the fixed magnetic disk device of the embodiment, and FIG. 4 is an assembly explanatory diagram of the fixed magnetic disk device of the embodiment. 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, a coil 6 is fixed to the other end of the carriage 5, and a permanent magnet 7 is provided.
And a voice coil motor by combining them so that the coil 6 is located between the permanent magnet 7 and the lower yoke 9 of the magnetic circuit 10 formed by the U-shaped upper yoke 8 and lower yoke 9 made of a magnetic material. The current control of the coil 6 causes the coil 6 to rotate based on Fleming's law, and the magnetic head 4 moves at high speed accordingly.
Positioned.

In this embodiment, as shown in FIG. 2, the protrusion 15 provided on the upper yoke 8 is fitted into the hole 16 provided on the lower yoke 9 for positioning, and the upper yoke 8 and the lower yoke 9 are connected to the upper yoke 8. It is held by the magnetic force 17 acting between the lower yokes 9 shown in FIG. At this time, as shown in FIGS. 1A and 3, the protrusion end surface 15 of the protrusion 15 of the upper yoke 8 is
The yoke stopper 20 presses the upper yoke 8 in the direction 21 orthogonal to the magnetic force 17 shown in FIG. The lower yoke 9 is fixed to the base 2 with the screw 14. In this case, the reverse method may be used. Further, the cushioning member 11 is fixed to the upper yoke 8 with an adhesive, and the cover 12 is fixed with screws 13 as shown in FIG. At this time, the upper yoke 8 is fixed by receiving a force in the direction of the magnetic force 17 shown in FIG. Note that it is necessary to select an adhesive and a buffer member 11 that do not generate a gas that causes adsorption between the magnetic disk 1 and the magnetic head 4. In addition, the buffer member 11 covers the cover 1.
It may be adhered to the lower surface 12a of the second. Although the hole 16 is exaggeratedly enlarged in FIG. 1B, the clearance between the hole 16 and the protrusion 15 is about 0.1 to 0.2 mm.

In this embodiment, the projection 11 has a rectangular shape, but any shape can be used 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.

[0013]

According to the present invention, the magnetic circuit is fixed by sandwiching the buffer member between the lower surface of the cover and the upper surface of the upper yoke of the fixed magnetic disk device, and the side yokes are integrated with the upper yoke at both ends of the upper yoke. Since the upper yoke and the lower yoke are fixed to the upper surface of the base of the fixed magnetic disk device via the stopper member that abuts on the side surface of at least one of the side yokes, the upper yoke and the lower yoke are not separated, and the upper yoke and the lower yoke are not separated. There is no deviation from the lower yoke, and the reliability of the fixed magnetic disk device can be improved.

[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.

FIG. 3 is a magnetic circuit assembly diagram of the fixed magnetic disk device in this embodiment.

FIG. 4 is an assembly explanatory diagram of a fixed magnetic disk device in this embodiment.

5A and 5B are configuration diagrams of a conventional example, in which FIG. 5A is a plan view of a fixed magnetic disk device, and FIG. 5B is a cross-sectional view taken along line BB of the fixed magnetic disk device.

FIG. 6 is an explanatory diagram of a magnetic circuit assembly of a conventional fixed magnetic disk device.

[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 8b upper yoke upper surface 8c upper yoke lower end lower surface 9 lower yoke 9a lower yoke upper surface 10 magnetic circuit 11 cushioning member 12 cover 13 Screw 14 Screw 15 Protrusion 15a Protrusion end face 16 Hole 16a Hole end face 17 Magnetic force 20 Yoke stopper 21 Magnetic force orthogonal direction

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, and said upper yoke being at both ends thereof. It has a side yoke integrated with the upper yoke, and a protrusion is provided at 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, and the upper yoke and the lower yoke are connected. In the magnetic circuit of the voice coil motor which is held by the magnetic force generated between them, the first fixing means for fixing the lower yoke lower surface of the side yoke of the upper yoke against the upper surface of the lower yoke, A second fixing means for fixing the end surface of the protrusion of the upper yoke in contact with the end surface of the hole portion. Fixing structure over the magnetic circuit. 2. The fixing structure according to claim 1, wherein the first fixing means fixes the fixed magnetic disk device by sandwiching a cushioning member between the lower surface of the cover and the upper surface of the upper yoke. Fixed structure of voice coil motor magnetic circuit. 3. The fixing structure according to claim 1 or 2,
The second fixing means fixes the upper yoke and the lower yoke to the upper surface of the base of the fixed magnetic disk device via stoppers that abut on at least one side yoke side surface of the side yoke integrated with the upper yoke at both ends of the upper yoke. The fixed structure of the magnetic circuit of the voice coil motor, which is characterized in that