JPH0634570B2 - Voice coil motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor, and more particularly to a voice coil motor with an improved magnet assembly, which is suitable for reducing vibration of a positioning device.

[Background of the Invention]

Generally, a magnetic head assembly for reading and writing data information is used for a magnetic disk storage device, an optical lens assembly is used for an optical disk storage device, and a wafer is used for an exposure device in semiconductor manufacturing. There are required mechanical units, and voice coil motors are often used to drive and position these mechanical units.

For example, as an example of a conventional positioning device, a voice coil motor in a positioning device of a magnetic disk storage device will be described with reference to FIG.

FIG. 5 is a perspective view of a positioning device for a general magnetic disk storage device.

In FIG. 5, 1 is a magnet assembly, 2 is a voice coil, and these magnet assembly 1 and voice coil 2 constitute a voice coil motor 3.

Reference numeral 4 is a carriage main body, 5 is a guide arm connected to the carriage main body 4, and 6 is a magnetic head assembly attached to the tip of the guide arm 5.

The carriage main body 4 is directly connected to the voice coil 2, and when the voice coil motor 3 is driven, the magnetic head assembly 6 performs a required operation via the carriage main body 4 and the guide arm 5, and the voice coil motor 3 is operated. Positioning is done.

Although not shown, the pivot shaft 7 is rotatably supported by a carriage block fixed to a base so that the carriage main body 4 can be rotated in a fan shape around the pivot shaft 7. It is configured.

That is, the movable portion for moving the magnetic head assembly 6, which should be referred to as a positioning target, is composed of the voice coil 2, the carriage main body 4, the guide arm 5, and the magnetic head assembly 6.

On the other hand, the support mechanism that supports the movable part and proposes the fan-like rotation motion is composed of the pivot shaft 7 and the carriage block. The magnet assembly 1 of the voice coil motor 3 is fixed to the carriage block of the support mechanism.

In such a precise positioning device for a magnetic disk storage device, since minute vibrations adversely affect the performance of the device,
The vibration amplitude has been reduced by taking measures such as increasing the rigidity of the positioning mechanism or increasing the damping.

For example, in the one described in JP-A-57-195367, the pivot shaft forming the support mechanism has a damping effect,
Further, in the one disclosed in Japanese Patent Laid-Open No. 59-162670, the voice coil portion forming the movable portion has a damping effect.

However, if the positioning device is considered as a structure including the magnet assembly, the vibration modes include modes involving rigid body deformation and elastic deformation of the magnet. No consideration was given to reducing the amplitude of the magnet assembly in order to reduce the vibration amplitude of the entire positioning device.

[Object of the Invention]

The present invention has been made in view of the above-mentioned conventional state of the art, and dissipates the vibration energy generated in the positioning device in the magnet assembly to reduce the vibration of the device.
It is an object of the present invention to provide a voice coil motor capable of improving positioning accuracy and shortening the time required for positioning.

[Outline of Invention]

The configuration of the voice coil motor according to the present invention is a voice coil motor comprising a voice coil and a magnet assembly, which is connected to a shin support mechanism for guiding a movable part of an object to be positioned, and drives the movable part to perform positioning. ,
A viscoelastic body is interposed in the connecting portion of the magnet assembly.

The concept of developing the present invention will be described with reference to FIGS. 6 to 9.

Here, FIG. 6 is a diagram of a transfer function representing the mechanical characteristics of the positioning device, FIGS. 7 and 8 are side views of a conventional magnet assembly, and FIG. 9 is a characteristic view of the magnet assembly alone. It is a diagram of the transfer function showing a vibration characteristic.

The mechanical characteristics of the positioning device are represented by the transfer function x / i of the input current i and the change x, as shown in FIG.

In FIG. 6, the horizontal axis represents the frequency f [H _Z ] and the vertical axis represents the phase [de].
g], amplitude [dB], and transfer function x / i. f
The mode ₁ is a natural vibration mode mainly due to the deformation of the fixed part of the apparatus, and the mode f ₂ is a natural vibration mode mainly due to the deformation of the movable part.

In order to improve the positioning accuracy of this position and to shorten the positioning time, as shown in FIG. 6, the amplitude of the amplitude at the frequency at which the phase is inverted deviates from the OdB line, that is, the gain margin G is increased. It is necessary to lower the height of the peak of the frequency f ₁ to improve controllability and settle residual vibration as quickly as possible.

The amplitude of the magnet assembly may be large in the natural vibration mode mainly due to the deformation of the fixed part of the device. This phenomenon occurs especially when the positioning device is driven at high speed. This is because when a large current is passed through the voice coil to increase the Lorentz force, the reaction acting on the magnet also increases, and the magnet assembly is vibrated.

By the way, a typical structure of the magnet assembly is as shown in FIG. 7 or FIG.

In FIG. 7, 10 is a magnet, 11 is a yoke, 1
Reference numeral 1-1 is a side yoke, 12 is a center yoke, and these are combined to form a magnet assembly 1 '.

The connection between the magnet 10 and the yoke 11 is often an adhesive, but the connection between the yoke 11 and the side yoke 11-1 and the connection between the side yoke 11-1 and the center yoke 12 are performed.
The connection with is made rigid with bolts.

The magnet assembly 1 ″ in FIG. 8 has a structure in which a counter yoke 13 is added to the structure in FIG. 7. The counter yoke 13 and the yoke 11 are connected to each other, and the counter yoke 13 and the center yoke 12 are combined. It is made rigid with bolts etc. to connect with.

Therefore, the internal damping of the single unit such as the magnet assembly 1 ', 1 "is small, and, for example, the transfer function x / i when free vibration is performed by striking is sharp as shown in FIG. Peaks.

Therefore, the voice coil motor of the present invention is designed to have a damping effect at the coupling portions of the magnet assemblies 1'and 1 "so that the vibration energy is dissipated there.

Example of Invention

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

First, FIG. 1 is a side view of a magnet assembly according to an embodiment of the present invention.

In the magnet assembly 1 shown in FIG. 1, the magnet 10 is bonded to the yoke 11, and the yoke 11 and the side yoke 11 are connected.
-1 is connected with a bolt, and the side yoke 11-1 and the center yoke 12 are also connected with a bolt.

On the other hand, the counter yoke 13 and the viscoelastic body 20 are interposed, and they are connected to the yoke 11 and the center yoke 12 with bolts.

The viscoelastic body 20 contains 0.1% in order to reduce the leakage flux.
It is recommended to use a thin thickness of mm or less. Considering workability,
A cellophane tape coated with an adhesive may be used. Alternatively, a commercially available tape-shaped damping material may be used. Alternatively, it may be thin rubber.

The center yoke 12 is surrounded by the center yoke 12.
The voice coil 2 shown in FIG. 2 is inserted in the magnetic space between the segment 10 and the segment 10 to form the voice coil motor 3.

That is, when the voice coil 2 is positioned on the magnetic flux force generated by the arrangement of the magnets 10 and the Lorentz force when the voice coil 2 is energized is used as the thrust, the voice coil 2
However, linear movement is performed in the axial direction of the center yoke 12.

The voice coil motor provided with the magnet assembly 1 of this embodiment is applied to, for example, the positioning device of the magnetic disk storage device described above with reference to FIG.

Voice coil 2, carriage main body 4, guide arm 5,
A support mechanism for guiding the movable parts such as the magnetic head assembly 6 is a carriage block (not shown) connected to the magnet assembly 1 provided with a pivot shaft 7 for linearly moving the voice coil 2. It is supporting to convert it into a dynamic movement.

The positioning device of a magnetic disk storage device with a magnet assembly has several natural vibration modes, among which is a mode of large displacement of the magnet assembly, which appears at a relatively low frequency, The gain margin G is reduced as in the mode of f ₁ shown in the figure.

However, in such a vibration mode, as described above, the magnet assembly 1 in which the viscoelastic body 20 is interposed between the yoke 11, the center yoke 12 and the counter yoke 13 is applied to the viscoelastic body. Energy is consumed in the portion 20 to reduce the displacement of the magnet assembly 1 and reduce the vibration amplitude of the entire positioning device of the magnetic disk storage device.

According to the present embodiment, the vibration energy generated in the positioning device of the magnetic disk storage device is dissipated inside the magnet assembly, so that the vibration of the device can be reduced, and the positioning accuracy is improved and the time required for positioning is improved. Can be shortened.

When the effect of vibration reduction is evaluated by the transfer function as shown in FIG. 6 showing the mechanical characteristics of the positioning device, the gain margin G at f ₁ increases by 3 dB or more. That is, the vibration amplitude is 30
% Or more. Along with this, the residual vibration is reduced, the positioning accuracy is improved, and the time for the vibration to settle can be shortened.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a side view of a magnet assembly according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. To do.

In the magnet assembly 1A shown in FIG. 2, a viscoelastic body 20 is interposed between the yoke 11 and the side yoke 11-1, and the connecting portions of the side yoke 11-1 and the center yoke 12 are bolted together.

The same effect as that of the previous embodiment can be expected also in the voice coil motor provided with such a magnet assembly 1A.

Next, still another embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a side view of a magnet assembly according to still another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 are the same parts as those in the embodiment of FIG. The description is omitted.

The magnet assembly 1B shown in FIG. 3 includes a viscoelastic body 2 as a part of members such as a yoke 11B and a counter yoke 13B.
They are connected so as to sandwich 0.

The same effect as that of the previous embodiment can be expected also in the voice coil motor provided with such a magnet assembly 1B.

Next, still another embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a side view of a magnet assembly according to another embodiment of the present invention.

In FIG. 4, 14 is a magnet, 15 is a yoke, and 1
Reference numeral 6 is a center yoke, and 17 is an outer yoke. A viscoelastic body 20 is interposed at a joint between the magnet 14 and the outer yoke 17, and a magnet assembly 1C is constituted by these.

In this embodiment, the outer yoke 17 and the center yoke 16 are
An example of a voice coil motor that uses a magnetic flux generated between a voice coil 2A and a voice coil 4A
The carriage main body directly connected to A is shown.

The voice coil motor having the magnet assembly 1C is expected to have the same effects as those of the above-described embodiments.

Although the above-described embodiments have been described with respect to the voice coil motor used for the positioning device of the magnetic disk storage device, the voice coil motor of the present invention is also applied to the positioning device of the exposure device in the optical disk storage device or semiconductor manufacturing. Therefore, similarly to each of the above-described embodiments, it is possible to realize low vibration, improvement of positioning accuracy, and reduction of positioning time.

Therefore, although not shown and described in detail, a linear guide supporting mechanism for transmitting the linear motion of the voice coil to the positioning object as a linear motion is provided outside the magnet assembly 1 shown in FIG. 1, for example. It goes without saying that it can also be applied to a positioning device.

Further, the same effect can be expected in a voice coil motor in which the center yoke of the magnet assembly or the yoke itself has a linear guide support mechanism.

〔The invention's effect〕

As described above, according to the present invention, the vibration energy of the deformation mode applied to the yoke and the side yoke via the magnet when the coil of the voice coil motor is moved is provided in the thin portion of the connecting portion between the yoke and the side yoke. Since it can be absorbed by the viscoelastic body, the positioning accuracy of the movable body is improved, and since the viscoelastic body can be thin, the magnetic flux passing through the yoke and the side yoke is not reduced,
The moving force to the coil can also be maintained.

[Brief description of drawings]

FIG. 1 is a side view of a magnet assembly according to an embodiment of the present invention, FIG. 2 is a side view of a magnet assembly according to another embodiment of the present invention, and FIGS. FIG. 5 is a side view of a magnet assembly according to still another embodiment of the present invention.
FIG. 6 is a perspective view of a positioning device of a general magnetic disk storage device, FIG. 6 is a transfer function diagram showing mechanical characteristics of the positioning device, and FIGS. 7 and 8 are views of a conventional magnet assembly. FIG. 9 is a side view of a transfer function representing the natural vibration characteristics of the magnet assembly itself. 1,1A, 1B, 1C ... Magnet assembly, 2,2A
... Voice coil, 3 ... Voice coil motor, 4, 4
A ... Carriage main body, 5 ... Guide arm, 6 ... Magnetic head assembly, 7 ... Pivot shaft, 10, 14 ... Magnet, 11, 11B, 15 ... Yoke, 11-1 ...
… Side yoke, 12, 16 …… Center yoke, 1
3, 13B ... Counter yoke, 17 ... Outer yoke, 20 ... Viscoelastic body.

Claims (1)

[Claims] 1. A magnet assembly comprising a facing yoke, a side yoke provided on at least one side of the yoke, and a magnet provided on each facing surface of the facing yoke, and between the magnets in the magnet assembly. In a voice coil motor including a movably provided coil and a movable body provided in the coil, a yoke is provided at a coupling portion between the facing yoke and the side yoke via a magnet when the coil is moved, A voice coil motor comprising a thin viscoelastic body that absorbs vibration energy of a deformation mode applied to a side yoke.