JPH03183349A - Voice coil motor - Google Patents

Abstract

PURPOSE:To enable high-speed access by opposing a soft magnetic metal plate and a fixed magnetic pole, across minute spaces, to one side and the other side, respectively, of a rotor disc, where electrically coupled plural coils are integrated with resin. CONSTITUTION:A rotor disc 14 is fixed to a rotary shaft 13, which is beared with the bearings 16 and 17 provided in a housing 10. For the rotor disc 14, electrically coupled plural winding coils 15 are bonded and united. The rotor disc 14 is opposed to a soft magnetic metal plate 12 and a fixed magnetic pole 23, supported by a fixed magnetic pole yoke 25, across minute spaces 21 and 22. The magnetic pole yoke 25 snaps at a metallic plate 12 with plural fixing claws 26. The fixed magnetic pole 23 is composed of a permanent magnet 24 and the yoke 25. The number of the fixed poles 23 is set to the double of the number of coils 15. The rotor disc 14 is so made that it may not rotate around the rotary shaft 13 more than half a time. Hereby, the rotor disc 14 is constituted thin, and high-speed access can be done.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a voice coil motor provided for access in a magnetic storage device or the like.

(Prior Art) Among many file devices, magnetic disk devices have been used as external storage devices in computer systems because they have a large storage capacity and can be accessed at high speed. Recently, many small magnetic disk drives have come to be used in small information processing systems such as personal computers and word processors.

These compact magnetic disk devices have improved electromagnetic conversion systems, positioning servo mechanisms, etc. in order to record and reproduce information with high density, high precision, and high speed. Various techniques have been provided for techniques such as equalization and deletion of defects, improvements in recording methods, recording correction, waveformization, and the like.

On the other hand, in the positioning servo mechanism, techniques have been provided for making the seek system highly accurate, high speed, and highly stable.

The head drive mechanism used in this positioning servo mechanism uses a voice coil motor as the thrust source to move the magnetic head directly connected to it, and a direct current motor and stamping motor, which uses the rotational force to drive the steel heald. There is one in which a magnetic head mounted on a carriage is moved via a magnetic head.

In terms of seek speed, the voice coil motor system has a mechanism that can best accommodate higher speeds, and is used for high-capacity drives that require high-speed access. on the other hand,
Stamping motors are used for low-capacity, general-purpose drives with low seek speeds and low track densities. Further, a DC motor is used as having characteristics intermediate between the two.

Next, a positioning mechanism of a swing type access type magnetic head, which is often used in magnetic disks (ODD), will be explained.

FIG. 3 is a diagram showing a conventional magnetic head positioning mechanism.

In the figure, the floating seal of the magnetic herad slider 41 disposed at the tip of the magnetic head support device 4 is arranged in a direction perpendicular to the longitudinal direction of the magnetic head support device 4 . A swing arm 2 located near the rotating magnetic disk 1 swings around a pivot 3 provided at one end, and a magnetic head support device 4 mounted at the other end is movable in the radial direction of the magnetic disk 1. It's Toshide.

FIG. 4 is a diagram showing another conventional magnetic head positioning mechanism.

In the figure, the floating seal of the magnetic head slider 41 of the magnetic head support device 4 is arranged in a direction that coincides with the longitudinal direction of the magnetic head support device 4 . A swing arm 2 located near the rotating magnetic disk 1 swings around a pivot 3 provided approximately at the center of the swing arm 2, and a magnetic head support device 4 mounted on one end of the swing arm 2 swings around a pivot 3 provided at approximately the center thereof.
is disposed so as to be movable in the radial direction.

In these magnetic head positioning mechanisms, when a magnetic head seek command is given from the host side, the access motor 5 rotates and is connected to the swing arm 2 via a steel belt 7 fixed to a pulley 6 fixed to its rotating shaft. Power is transmitted to move the magnetic head support device 4 to the magnetic disk l.
Data is written/read by moving the target track in the radial direction and seeking to the target track.

(Problem to be Solved by the Invention) However, in the magnetic head positioning mechanism configured as described above, the track pitch on the surface of the magnetic disk 1 is determined by the rotational index number of the access motor 5 and the power transmission mechanism of the pulley 6 and the swing arm 2. It is determined by the reduction ratio of In order to obtain a high trunk density, it is necessary to reduce the radius r of the pulley 6, increase the rotation radius R of the swing arm 2, and increase the number of slits in the access motor 5 to increase the number of rotation indexes.

However, when the radius r of pulley 6 becomes smaller, Boo IJ6
To! The bending stress of the tight steel heald 7 increases, leading to fatigue failure, and there is a limit to reducing the radius due to the fatigue strength of the steel heald 7.

On the other hand, if the rotation radius R of the swing arm 2 is increased,
The main body of the magnetic head positioning mechanism becomes large.

Furthermore, in order to increase the access speed, it is necessary to use a high-output access motor 5, increase the rigidity of the power transmission element of the positioning system, and increase the servo gain of the control circuit.

However, as the output of the access motor 5 increases, the volume increases and the power consumption also increases, so increasing the rigidity of the power transmission element does not allow the device to be made smaller, lighter, and thinner. Furthermore, when the servo gain of the positioning control circuit is increased, the circuit oscillates and the mechanical section resonates, resulting in poor controllability and deterioration of the accuracy of high-speed positioning of the magnetic head. As the size of the device increases, problems arise such as the inability to maintain an accurate on-track state against disturbances such as vibrations and shocks.

Furthermore, as the device becomes larger, the mechanism becomes more complicated and requires accurate assembly using assembly jigs, which impairs work efficiency.

The present invention solves the problems of the conventional magnetic head positioning mechanism described above, provides good controllability, high high-speed positioning accuracy of the magnetic head, is resistant to vibrations, and performs high-density writing/writing without increasing the size of the device. An object of the present invention is to provide a voice coil motor that can perform reading.

(Means for solving the five problems) For this purpose, in the voice coil motor of the present invention,
It has a rotating shaft supported by a housing or the like via a bearing, and a rotor disk fixed to the rotating shaft.

On one side of the rotor disk, soft magnetic metal plates are placed facing each other with a small gap, and on the other side, fixed magnetic poles are placed facing each other with a similarly small gap. has been done. The rotor disk is formed by fixing and integrating a plurality of electrically coupled wire-wound coils using an adhesive, a resin such as a plastic mold, or the like.

(Function) According to the present invention, as described above, a soft magnetic metal plate is placed on one surface of the rotor disk supported by the rotating shaft with a minute gap, and a similarly minute gap is placed on the other surface. Na Sora I! Since the fixed magnetic poles are arranged at intervals of t, the rotor disk rotates around the rotation axis due to the current flowing through the winding coil.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a voice coil motor of the present invention, FIG. 1(A) is a plan view of an actuator of the voice coil motor, and FIG. 1(B) is a sectional view of the actuator of the voice coil motor.

In the figure, the actuator 11 is assembled using a soft magnetic metal plate I2 as a base. A rotor disk 14 is fixed to the rotating shaft 13, and the rotor disk 14 is formed by fixing and integrating a plurality of electrically coupled wire-wound coils 15 with adhesive or plastic molding.

The rotating shaft 13 is also supported in the housing IO via a bearing 16.17 and is preloaded via a spring element 18 arranged between the rotating shaft 13 and the inner ring of the hair ring 16.17. There is.

In this way, the rotor disk 14 integrated with the rotating shaft 13 is connected to the metal plate 12 with a minute gap 21 on one side.
, and faces a fixed magnetic pole 23 supported by a fixed magnetic pole yoke 25 with a similarly minute air gap 22 on the other side. Therefore, the fixed magnetic pole yoke 25 has a plurality of fixed claws 2.
It is snap-engaged with the metal plate 12 via 6.

The number of fixed magnetic poles 23 is twice the number of wire-wound coils 15 composing the rotor disk I4, and the rotor disk 14 is designed not to make more than half a turn around the rotating shaft 13. It is configured.

The fixed magnetic pole 23 is composed of an assembly of a permanent magnetic pole 24 and a fixed magnetic pole yoke 25 that supports it. The permanent magnetic flux generated by the permanent magnetic pole 24 passes from the fixed magnetic pole yoke 25 through the air gap 22, passes through the inside of the metal plate 12, and then passes through another air gap 21 again to form a closed loop magnetic path.

Next, the operation of the voice coil motor having the above configuration will be explained.

Figure 2 is an explanatory diagram of the operation of the voice coil motor of the present invention, Figure 2 (A) is a diagram of the relationship between rotation angle θ and field magnetic flux density distribution B (θ), and Figure 2 (B) is the winding coil arrangement. It is a diagram.

The figure shows a state in which one of the plurality of wire-wound coils 15 is within the magnetic flux represented by the field VA magnetic flux density distribution B(θ). An angle θ is taken in the rotation direction of the permanent magnetic pole 24 from an arbitrary base line OY that crosses the center ○ of the permanent magnetic pole 24. permanent magnetic pole 2
When the number of poles of 4 is P and 1 flux is BIll, the field magnetic flux density distribution B(θ) is approximated by the following (1).

Here, when θ-τ, θ is the angle giving the node.

At this time, the magnetic flux φ(θ) interlinking with − winding coils 15
is a patent in which the inner diameter of the winding coil 15 is R+ and the outer diameter is characterized by the induced electromotive force C4, where the number of turns of the - winding coil 15 is N, and the number of winding coils 15 connected in series is m.
is given by Pdθ C05-T'-θ"...(3).

Moreover, the torque T generated in the actuator 11 is Ia
If is the current flowing through the winding coil 15, then T=mN(R
%−R+”)[a Bm · Therefore, the back emf constant as the actuator constant! and the torque constant are: Kg −Kt = mKo C05−
T-θ...(5).

The current Ta flowing through the winding coil 15 is as follows, where the winding coil resistance is Ra, Ia = −(E, −KE −”) (7) mRa
It is given by dt. however,
E is the drive voltage of the actuator 11.

The above describes the actuator U of the voice coil motor of the present invention.
Can perform calculations of the main specifications of.

When the load inertia J is coupled to the rotating shaft 13 of the actuator 11, the equation of motion is d2θ J dL 2 =K y I a '.
By solving this equation of motion, the dynamic behavior of the load and the dynamic behavior of the electrical system can be explained.

A conventional head access DC motor has a plurality of phase winding coils, and excitation of the phase windings is switched in accordance with the rotation angle of the rotor. For this reason, in the case of the phase excitation switching method, there are always phase windings that are not excited, resulting in low efficiency.

Furthermore, when a plurality of wire-wound coils 15 are provided as in this embodiment, they may be connected in series or in parallel. That is, the impedance can be arbitrarily selected so as to fall within the range of impedance allowed in relation to other constituent members.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As explained above, according to the present invention, a soft magnetic metal plate is placed on one surface of the rotor disk supported by the rotating shaft with a minute gap, and the soft magnetic metal plate is placed on the other surface of the rotor disk. Similarly, since the fixed magnetic poles are arranged with a small gap in between, the rotor disk can have an extremely thin structure.

Therefore, the mass of the movable part of the head positioning device is reduced, which not only enables high-speed access, but also increases rotational torque and improves writing/continuation performance.

[Brief explanation of drawings]

Figure 1 is a diagram showing the voice coil motor of the present invention, Figure 1 (A) is a plan view of the actuator of the voice coil motor, Figure 1 (B) is a sectional view of the actuator of the voice coil motor, and Figure 2 is An explanatory diagram of the operation of the voice coil motor of the present invention, Fig. 2 (A) shows the rotation angle θ and the field magnetic flux density distribution B.
(θ), Figure 2 (B) is a winding coil arrangement diagram, Figure 3 is a diagram showing a conventional magnetic head positioning mechanism, and Figure 4 is a diagram showing another conventional magnetic head positioning mechanism. be. 11...Actuator, 14...Rotor disk, 15...11 coil, 16.17...Bearing, 21.22...Gap, 23...Fixed magnetic pole.

Claims (1)

[Claims] (a) a rotating shaft; (b) a rotor disk fixed to the rotating shaft; (c)
(d) a soft magnetic metal plate facing each other with a small gap on one side of the rotor disk; (d) fixed magnetic poles facing each other with a small gap on the other side of the rotor disk; ) and a voice coil motor, characterized in that the rotor disk is formed by integrally fixing a plurality of electrically coupled wire-wound coils with resin.