JPH03183348A - Voice coil motor - Google Patents

Abstract

PURPOSE:To improve servo following properties by fixing a restricting plate through a sticking layer, which absorbs vibration, to at least one side of a voice coil, which has a movable coil generating a circular locus, with permanent magnets arranged in opposition. CONSTITUTION:Yokes 52 and 53, each of which form one part of a magnetic circuit, are attached to the top and the bottom, respectively, of housing 51, and permanent magnets 55 and 57 are mounted at the surfaces. The permanent magnets 55 and 57 are arranged in opposition at a specified interval, and a movable coil 58, which is mounted through a mounting arm 59 on a swimming arm 4 rotating horizontally around a shaft 11, shifts in circular are shape within the gap. Restricting plates 20 consisting of, for example, stainless plates are fixed through sticking layers 21 to the top and the bottom of the movable coil 58. For the sticking layer 21, high loss material having elasticity is used so that it may absorb vibration energy. Hereby, even if the movable coil 58 generates vibration at a resonance point, the vibration energy is absorbed, and the vibration is suppressed, and the generation of noise is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voice coil motor used as a head drive source of a hard disk device or the like.

[Conventional technology]

Although there are various types of storage devices for computers and the like, there is a hard disk device that is characterized by its large storage capacity, fast access, and small size.

FIG. 6 is a plan view showing an example of this type of disk device.

As shown in Figure 6, the hard disk device has multiple (
For example, the magnetic heads 2 are arranged so that each pair of heads sandwich each surface of >2 magnetic disks 1, and further,
A swing arm 4 having a magnetic head 2 at its tip and a head drive mechanism 6 for swinging the swing arm 4 are provided. Swing arm 4, voice coil motor (
A voice coil motor (hereinafter referred to as VCM) 5 and a spatula drive mechanism 6 are attached together with a DD motor (not shown) to a base plate 7 that serves as the base of a casing that holds each member in a sealed state from the outside.

A printed circuit board (not shown) on which a motor drive circuit, a control circuit, etc. are mounted is attached to the base plate +-7 via a frame (not shown). The head drive mechanism 6 is
A swing arm 4, a yoke 8 holding a magnet (not shown), a coil 9 movably disposed within the yoke 8,
A flexible printed circuit board that includes a shaft 11 that rotatably fixes the swing arm 4 to the frame side, and a flexible printed circuit board that is temporarily fixed to the side of the swing arm 4 and has wiring for exchanging signals with the magnetic head 2 and energizing the coil 9. 12, this flexible printed base Fi, is composed of a fixing member 13 that fixes the other end of the flexible printed base Fi.

The casing housing each of the above-mentioned members is protected from the base plate 7 and the top cover (not shown), and a gasket is used at the contact area between the base plate 7 and the top cover to maintain confidentiality, and the DD motor is protected from the casing. The shaft portion is filled with magnetic fluid.

Next, the operation of the hard disk device with the above configuration will be explained.

This type of disk drive device is designed to set each recording track and V in advance.
The excitation conditions of CM5 are stored in a memory (both not shown) in a controller including a CPU,
The magnetic head 2 can be positioned depending on the driving condition of the VCM 5.

Therefore, during operation, the drive circuit selects any recording track to be recorded or reproduced in response to a command from the host computer. In the process of tracking this recording track, when the gap of the magnetic head 2 is located at a servo sector, a pair of servo signals formed in a staggered manner on the magnetic disk 1 are read out. The read servo signal is amplified by the head amplifier, and based on the servo signal output from the head amplifier, the drive circuit
The CM 5 is controlled to move the magnetic head 2 in the radial direction of the magnetic disk 1. By this control, the gap of the magnetic helad 2 is positioned on the center of the track width of the recording track. Thereafter, the VCM 5 is driven every time a servo signal is detected, and the magnetic head 2 is always positioned on the track, allowing stable data reading or writing.

FIG. 7 is a sectional view showing the details of the VCM 5, and FIG. 8 is a perspective view of the main part showing the moving coil portion.

As shown in FIGS. 7 and 8, yokes 52 and 53 forming part of a magnetic circuit are attached to the top and bottom of the housing 51, and permanent magnets 54 and 55, which function as rotors, are attached to each surface of the yokes 52 and 53, which form part of a magnetic circuit. and 56°57 are installed. Permanent magnets 54, 56 and 55, 57 are arranged facing each other with a predetermined gap, and a ring-shaped moving coil 58 is disposed so as to be horizontally movable within the gap. The moving coil 58 is normally installed between the permanent magnets. Furthermore, both sides of the movable coil 58 are fitted between attachment arms 59 and 59 of the swing arm 4 on which the magnetic head 2 is mounted, and the movable coil 58 is fixed to the swing arm 4.

In FIG. 7, when a current is applied to the moving coil 58,
A torque is applied to the movable coil 58 so that it moves circularly around the axis 11 along the permanent magnet.

Therefore, the movable coil 58 rotates about the shaft 11, the magnetic head 2 rotates about the swing arm 4 as a radius of rotation, and seek is performed on the disk. Depending on the current direction to the moving coil 5B, the moving coil 58
rotates to the right or left.

Problem to be Solved by Invention C] By the way, in the prior art, there is a resonance point due to the relationship between the shape of the moving coil 58 and Young's modulus, and as shown in the characteristic diagram of FIG. is high. therefore,
At the resonance point P, the vibration of the movable coil 58 does not act as a torque to drive the swing arm 4, and the servo followability at the resonance point P is poor, causing off-track. In addition, there were problems such as large vibrations at the resonance point and generation of noise.

The present invention has been made in view of and to solve the problems of the prior art, and its purpose is to prevent vibrations of the moving coil, improve servo followability, and reduce noise. Our goal is to provide voice coil motors that can.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a magnetic field generator comprising a permanent magnet for generating a magnetic field, and a movable coil that is disposed opposite to this permanent magnet and rotates while drawing an arc locus along this permanent magnet. In a voice coil motor for a recording/reproducing device, a restraining plate is fixed to at least one side of the movable coil via an adhesive layer that absorbs vibrations.

[Effect]

With the above means, even if the moving coil is driven at the resonance point and vibration is generated in the moving coil, the vibration energy that causes the moving coil to deform is absorbed by the viscosity M between the moving coil and the restraining plate.
It is absorbed by layers and suppresses deformation of the moving coil.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 4.

Fig. 1 is a sectional view of the main parts of the voice coil motor according to the present invention, Fig. 2 is a perspective view of the main parts, Figs. 3 (a) and (b) are explanatory diagrams showing operating states, and Fig. 4 is a characteristic diagram. , FIG. 5 is a bottom view of the cover. Note that the same parts as those of the conventional example shown in FIGS. 6 to 8 are given the same reference numerals, and redundant explanation will be omitted.

This embodiment differs from the conventional structure in that the upper and lower surfaces of the moving coil 58, that is, the permanent magnets 54, 55 and 56.
A restraining plate 20 made of a highly rigid material, such as a stainless steel plate, is fixed to the surface facing the plate 57 via an adhesive layer 21. This restraining plate 20 has a flat ring shape that matches the shape of the movable coil 58.

Furthermore, the adhesive layer 21 is made of an elastic, high-loss material to absorb vibration energy.

In the above-mentioned embodiment with the grooved bottom, when the movable coil 58 vibrates at the resonance point, the movable coil 58 changes from the normal state in FIG. 3(a) to the vibration state in FIG. 3(b). bend.

At this time, the movable coil 58 is connected to the restraint plate 2 through the adhesive layer 21.
Since the movable coil is fixed at 0, the deflection of the moving coil 5 occurs while deforming the adhesive layer 2. The vibration energy of the movable coil 58 is absorbed by the deformation of the adhesive layer 21, and the vibration of the movable coil 58 can be suppressed.

A characteristic diagram of this embodiment is shown in FIG. 4, and as shown in FIG. 4, the gain at the resonance point P can be lowered compared to FIG. 9. Therefore, vibration of the movable coil 58 can be prevented and positioning accuracy can be improved, so servo tracking at the resonance point can be improved, off-track can be prevented, and noise can be reduced.

Note that the restraining plate 20 may be made of a magnetic material, whereby the lines of magnetic force emitted from the permanent magnets are directed toward the magnetic restraining plate, allowing the lines of magnetic force to efficiently pass through the moving coil. .

Reference numeral 22 denotes a sound insulating material fixed to the inner surface of the cover, which insulates noise generated within the device and prevents it from escaping outside.

Although the invention made by the present invention has been specifically explained based on Examples above, it goes without saying that the present invention is not limited to the above-mentioned Examples and can be modified in various ways without departing from the gist thereof. .

〔Effect of the invention〕

As described above, according to the present invention, vibration of the moving coil can be prevented, servo followability can be improved, and noise can be reduced.

[Brief explanation of drawings]

1 to 5 are for explaining one embodiment of the present invention, in which FIG. 1 is a sectional view of a main part of a voice coil motor according to the present invention, FIG. 2 is a perspective view of a main part, and FIG. Figure (a),
(b) is an explanatory diagram showing the operating state, Fig. 4 is a characteristic diagram, and Fig. 5 is an explanatory diagram showing the operating state.
The figure is a bottom view of the cover, Figures 6 to 9 are for explaining a conventional voice coil motor, Figure 6 is a plan view showing an example of a disk device using a voice coil motor, and Figure 7 is a plan view showing an example of a disk device using a voice coil motor. 8 is a sectional view showing the voice coil motor, FIG. 8 is a perspective view of a main part showing the moving coil portion of FIG. 5, and FIG. 9 is a characteristic diagram. 20・・・・・・Restriction plate, 21・・・・・・・・・
・Adhesive layer, 54°55.56.57・・・・・・・・・
Permanent magnet, 58...Moving coil. ] Figure Figure Figure Figure Figure Frequency Figure 3

Claims (1)

[Claims] A voice coil motor for a magnetic recording/reproducing device comprising a permanent magnet for generating a magnetic field, and a movable coil disposed opposite to the permanent magnet and rotating while drawing an arc locus along the permanent magnet, wherein the movable coil A voice coil motor, characterized in that a restraint plate is fixed to at least one side of the motor via an adhesive layer that absorbs vibrations.