JPH06121514A - Voice coil motor - Google Patents

Abstract

PURPOSE:To enhance mechanical strength of yoke by providing a coil applied slidingly over a center core disposed between one pair of side faces of a rectangular frame yoke, and a permanent magnet disposed on the inside of the other side face of the yoke with the yoke being formed integrally. CONSTITUTION:A yoke 1 is formed by punching a rectangular parallelepiped high tension steel having high mechanical strength into a rectangular frame. Magnets 4a, 4b having high coercive force and the size corresponding to the movable range of a coil 3 are bonded tightly to the inside surfaces of upper and lower yokes 1a, 1b. A square columnar center core 2 made of same high tension steel as the yoke 1 is interposed between side yokes 1c, 1d. The center core 2 is secured, at the opposite ends 2a, 2b thereof, to the central part of the side yokes 1c, 1d by means of center core assembling bolts 6. The rectangular frame coil 3 is applied over the center core 2 while keeping a predetermined gap between.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a voice coil motor suitable for application to a precision positioning device or the like.

[0002]

2. Description of the Related Art Generally, a magnetic disk device is connected to a computer main body through a control device and moves a magnetic head to a predetermined track of a predetermined magnetic disk based on a control signal and address information from the computer main body. By letting
Information is written and read. The control of moving the magnetic head to a predetermined track is performed by a precision positioning device, and based on the position of the magnetic head detected by a laser linear encoder etc. and the address information from the computer body, feedback control is performed to the voice coil motor. Positioning control is performed by moving the magnetic head using a linear air bearing or the like.

A conventional voice coil motor in which a magnetic head is moved by a precision positioning device is, as shown in the side view of the voice coil motor 10 in FIG. 4, a yoke 1, a center core 2, a coil 3 and a magnet. It is composed of 4a and 4b. The yoke 1 is composed of four high-tensile steels or the like having high mechanical strength, and has an upper yoke 1a and a lower yoke 1b arranged in parallel at a predetermined interval, and a side yoke 1c connecting them. And 1d to form a rectangular shape, and the side yokes 1c and 1d and the upper yoke 1
The yoke a and the lower yoke 1b are integrated by a yoke assembly bolt 5. Then, the base mounting screw portion 7 is formed on the bottom surface of the lower yoke 1b.
b and the base are fixed with bolts.

Magnets 4a and 4b, such as a ferrite magnet having a high coercive force or a high-performance rare earth cobalt magnet, are adhered to the inner surfaces of the upper yoke 1a and the lower yoke 1b in correspondence with the movable range of the coil 3 described later. It is fixed with a drug. Between the side yokes 1c and 1d, a quadrangular prism-shaped center core 2 made of the same material as that of the yoke 1 is disposed so that both ends 2a and 2b thereof are in contact with the side yokes 1c and 1d, respectively. At the center of the side yoke 1 with the bolt 6 for assembling the center core,
c and 1d and both ends 2a and 2b of the center core 2 are fixed. As shown in FIG. 5, which is a cross-sectional view taken along the line XX of FIG. 4, the center core 2 has a rectangular frame-shaped coil 3 inserted in the inner peripheral surface of the center core 2 at a predetermined interval. It is slidably installed in 2.

An inverted L-shaped output take-out plate 8 is arranged on the coil 3, and a magnetic head or the like is attached to the upper part of the output take-out plate 8 to perform positioning control.

[0006]

However, in the positioning control by the voice coil motor, since the coil is moved by passing a current through the coil to generate a thrust, the reaction of the thrust acts on the yoke, and the conventional method described above is used. In this voice coil motor, the yoke is formed by fixing the four yoke members with the yoke assembly bolts, so the reaction of the thrust acts on the part fixed with the yoke assembly bolts, which has weak mechanical strength. For example, in FIG. 4, when the coil 3 moves to the side yoke 1d side, the yoke 1 is distorted to the side yoke 1c side and deformed into a rhombus as shown by a chain double-dashed line. There is.

Further, the deformation of the yoke 1 results in vibration of a frequency determined by the relationship between the thrust generated in the coil and the rigidity of the yoke, and it is not possible to perform precise positioning control with a high response above the frequency. There are also challenges.

[0008]

In order to achieve the above object, a voice coil motor according to the present invention comprises a yoke having a rectangular frame shape and a center core disposed between a pair of opposing side surfaces of the yoke. In a voice coil motor including a coil slidably inserted in the center core and a permanent magnet arranged inside the other side surface of the yoke, the yoke is integrally formed. It has a feature.

[0009]

According to the present invention, the yoke is integrally formed, so that the mechanical strength of the yoke is improved, and the yoke can be deformed even when a force is applied to the yoke by the reaction of the thrust generated in the coil. Moreover, the vibration generated by the deformation of the yoke is suppressed, and the accuracy of the positioning control is improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a positioning device of a magnetic disk device, and FIG. 1 shows a schematic configuration of the magnetic disk device. As shown in FIG. 1, in this magnetic disk device, the interface section B receives control signals and address information from the computer main body and sends them to the control circuit section C. Then, the control circuit unit C combines various control signals and issues a command for positioning the magnetic head D to the track specified by the address information to the positioning circuit unit E and a command to read information from the magnetic disk A. It is sent to the writing / reading circuit unit F. The servo signal output from the positioning circuit section E is supplied to the servo amplifier S to control the servo current of the voice coil motor 10. The positioning circuit section E and the voice coil motor 1
The positioning device is composed of 0 and 0.

The power supply used in each part of FIG. 1 is 200V.
10 commercial AC voltage of the power supply control interface unit U
The voltage is converted into an AC voltage of 0 V and supplied from the DC power supply unit P. The DC power supply unit P has DC power supplies 1 to 7, and converts the input 100V commercial AC power into predetermined DC power and outputs the DC power. The DC power supplies 1 to 7 are associated with power supplies to be used for each circuit unit, and the power output of the DC power supplies 1 to 3 is a precision power supply system including a servo amplifier S, a positioning circuit unit E, and a writing / reading circuit unit F. The installation terminal is connected to the installation bus bar 9. On the other hand, the power supply output of the DC power supplies 4 to 7 is supplied to a power supply system including an interface section B, a control circuit section C, a status circuit section N and a power supply control circuit section J, which have a relatively large noise margin, for installation. It is connected to the bus bar 10.

As shown in FIG. 2, the voice coil motor 10 is composed of a yoke 1, a center core 2, a coil 3 and magnets 4a and 4b as in the conventional case. The yoke 1 is formed in a rectangular frame shape by stamping a rectangular parallelepiped high-strength steel having high mechanical strength with a wire electric discharge machine such as a wire cut machine. Then, on the inner surfaces of the upper yoke 1a and the lower yoke 1b, which are the pair of yoke side surfaces facing each other, a ferrite magnet having a high coercive force of a size corresponding to the movable range of the coil 3 described later, or a high-performance rare earth cobalt. Magnet 4a such as a magnet
And 4b are adhered to each other with an adhesive. In addition, between the side yokes 1c and 1d, which are the other pair of opposing yoke side surfaces, a square columnar center core 2 made of the same high-tensile steel as the yoke 1 is placed in contact with the side yokes 1c and 1d. Both ends 2a and 2b of the center core 2 are fixed by a center core assembly bolt 6 at the center of the side yokes 1c and 1d. As shown in FIG. 3, which is a cross-sectional view taken along the line XX of FIG. 2, the center core 2 has a square frame-shaped coil 3 inserted in the inner peripheral surface of the center core 2 at a predetermined interval. It is loaded in the core 2. An inverted L-shaped output take-out plate 8 is attached to the coil 3, a magnetic head is attached to the upper part of the output take-out plate 8, and positioning control is performed by the voice coil motor 10 to bring the magnetic head to a predetermined position. It is moving.

Here, the center core 2 has side yokes 1c and 1d so that the side yokes 1c and 1d are not distorted when the both ends 2a and 2b of the center core and the side yokes 1c and 1d are fixed. And the length of the center core 2 are precisely equal.
Then, the bottom of the yoke 1 and the base are attached by the base attaching screw portion 7, whereby the yoke 1 is fixed to the base.

When the voice coil motor 10 of the above embodiment is used to perform positioning control, the servo signal output from the positioning circuit E based on the control signal from the computer main body is supplied to the servo amplifier S, Servo amplifier S
Outputs a servo current to the voice coil motor 10. This servo current is supplied to the coil 3 of the voice coil motor 10, and a thrust corresponding to the servo current is generated in the coil 3 by the servo current, and the coil 3 moves to the side yoke 1d side, for example. At this time, due to the reaction of the thrust generated in the coil 3, a force having the same magnitude as the thrust acts in the direction opposite to the thrust, that is, on the side yoke 1c side.
Since it is integrally formed and has high mechanical rigidity, it is not distorted by the reaction of thrust. Therefore, the vibration caused by the distortion caused by the reaction of the thrust does not occur, and the positioning control is performed accurately.

Therefore, according to the above embodiment, the yoke 1 is integrally formed by wire cutting or the like, so that the yoke 1 is distorted even when the reaction of the thrust generated in the coil 3 acts on the yoke 1. Since it is possible to prevent the vibration caused by the distortion generated in the yoke 1, it is possible to improve the accuracy of the positioning control. In addition, since the mechanical resonance frequency of the voice coil motor 10 becomes high, it is possible to shorten the time required for precise positioning with high response, that is, the positioning settling time.

In the above embodiment, the magnets are arranged at two places, the upper yoke and the lower yoke, but they may be arranged at only one place of the upper yoke or the lower yoke.

[0017]

As described above, according to the present invention, since the yoke is integrally formed, it is possible to prevent the yoke from being distorted due to the reaction of the thrust generated in the coil. Vibration caused by the above is prevented, and the accuracy of positioning control can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a magnetic disk device to which the present invention is applied.

FIG. 2 is a side view showing an embodiment of a voice coil motor according to the present invention.

FIG. 3 is a sectional view taken along line XX of FIG.

FIG. 4 is a side view of a conventional voice coil motor.

5 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 1 yoke 1a upper yoke 1b lower yoke 1c, 1d side yoke 2 center core 3 coil 4a, 4b magnet 5 yoke assembly bolt 6 center core assembly bolt 7 base mounting part 8 output extraction plate 10 voice coil motor

Claims (1)

[Claims] 1. A square frame-shaped yoke, a center core disposed between a pair of opposing side surfaces of the yoke, a coil slidably inserted in the center core, and a yoke of the yoke. A voice coil motor comprising a permanent magnet disposed on the inner side of the other side surface, wherein the yoke is integrally formed.