JPH04229062A - Rocking actuator - Google Patents

Abstract

PURPOSE:To further reduce the weight and to improve response considerably by integrally molding a member for holding a moving coil and an arm of a thermosetting resin having modulus of longitudinal elasticity higher than a specific value. CONSTITUTION:An arm 5 is molded of a thermosetting resin mixed with carbon fibers and a fixing hole 8a is made in the central part while a hole 8b for mounting a functional member such as a magnetic head is made at one end. A holding member 9 is molded integrally with the arm 5 so that it holds the moving coil 6 while surrounding. According to the constitution, weight at the part of the arm 5 can be reduced considerably as compared with a conventional one made of aluminum alloy and the access time can be shortened as compared with a conventional one. The material composing the arm 5 has modulus of longitudinal elasticity in the order of 40X10<4>kg/cm<2> which is sufficiently comparable with that of the aluminum alloy in the order of 68X10<4>kg/cm<2>.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a swing type actuator such as an actuator for a magnetic disk, and in particular to a swing type actuator in which a functional member such as a magnetic head swings in a circular arc trajectory. type) actuator.

0002

2. Description of the Related Art Conventionally, a swinging or rotating actuator as shown in FIGS. 4 and 5 has been used to position a magnetic head on a recording track of a magnetic disk or the like. In both figures, permanent magnets 2 are fixed to a yoke 1, and are arranged opposite to each other with different polarities, and assembled by columns 3 to form a magnetic circuit via a gap 4. Reference numeral 5 designates an arm, to which a flat moving coil 6 is fixed to one end and a magnetic head (not shown) to the other end, and the shaft 7 is fixed so that the moving coil 6 is located in the cavity 4. It is arranged so that it can rotate and swing freely.

When a signal current is applied to the moving coil 6, a driving force around the axis 7 acts on the moving coil 6 according to Fleming's left hand rule, causing the arm 5 to rotate and swing.
The magnetic head fixed to the arm 5 is positioned at a predetermined recording track on the magnetic disk. Note that the rotation direction is switched by reversing the direction of the current flowing to the coil.

FIG. 6 is a partially exploded, partially sectional plan view showing another example of a conventional swing-type actuator, and FIG. 7 is a view taken along arrow B in FIG. 6, and the same parts are shown in FIGS. 4 and 5. Indicated by the same reference numerals. In FIG. 6, 8 is a bobbin with a bottom plate, which accommodates the movable coil 6. The operation of the swing type actuator having such a configuration is similar to that shown in FIGS. 4 and 5, but since the permanent magnet 2 is fixed to only one of the pair of yokes 1, 1, It has the advantage of being thinner overall.

[0005]

[Problems to be Solved by the Invention] In the conventional magnetic disk actuator described above, the movable coil 6 is attached to the arm 5.
Adhesives are generally used to secure them. In the case shown in FIGS. 6 and 7, a movable coil 6 is bonded inside a bobbin 8 with a bottom plate, and then the bobbin 8 with a bottom plate is fixed to the arm 5 with screws (not shown).

However, the fixing work using an adhesive is not only complicated and has low workability, but also has problems in that the positioning accuracy of the moving coil is insufficient and reliability is low. Further, processing of the terminals of the moving coil 6 also requires complicated work, which also has the problem of reducing the workability of the entire assembly work.

[0007]Furthermore, in recent years in the field of magnetic disk drives, demands have become even more severe for devices to be smaller, thinner, more functional, etc., and the positioning accuracy of the moving coil 6 and the workability and reliability of the bonding work have become more demanding. It is necessary to improve the above requirements, and there is a problem in that conventional structures cannot satisfy the above requirements.

In order to solve the above-mentioned problems, the moving coil 6 is molded using thermoplastic resin to form the arm 5.
(For example, U.S. Pat. No. 4,855,853, U.S. Pat.
Publication No. 56, etc.). With such a configuration, the movable coil 6
The structure for holding the actuator becomes simple and can be made considerably thinner, which is advantageous in making the entire actuator more compact.

However, since the arm 5 is generally formed by die-casting an aluminum alloy, its specific gravity is high. Therefore, the capacity of the drive power source increases and the responsiveness tends to deteriorate. On the other hand, in recent years, portable information processing equipment has become popular, and such equipment is required to be smaller and lighter than conventional stationary equipment, consume less power, and have high responsiveness. However, there is a problem in that conventional actuators cannot meet the above requirements.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems existing in the prior art described above, and to provide a swing-type actuator that can further reduce the weight and significantly improve responsiveness.

[0011]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a permanent magnet is fixed to at least one of a pair of opposing yokes, and a magnetic gap is formed on the surface of this permanent magnet. A swinging type comprising a housing, a swingable arm having a movable coil fixed to one end and a functional member fixed to the other end, and the moving coil movably disposed within the magnetic gap. In the actuator,
The holding member that holds the moving coil and the arm have a longitudinal elastic modulus of 3.
We adopted a technical means of integrally forming it from a thermoplastic resin with a weight of 0x104 kg/cm2 or more.

In the present invention, the thickness of the holding member that holds the peripheral edge of the moving coil can be formed to be substantially the same as the thickness of the moving coil.

[0013]

[Operation] With the above structure, the responsiveness of the entire actuator can be improved, the positioning accuracy and reliability of the moving coil can be improved, and the workability can be greatly improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are a plan view and a vertical cross-sectional view of a main part showing an embodiment of the present invention, respectively, and the same parts are designated by the same reference numerals as in FIGS. 4 to 7. In both figures, the arm 5 is made of, for example, carbon fiber-containing thermoplastic resin (Sumitomo Bakelite MK-2), has a mounting hole 8a in the middle, and has a functional member such as a magnetic head (not shown) at one end. ) A mounting hole 8b is provided. Next 9
A holding member is formed integrally with the arm 5 so as to hold the periphery of the movable coil 6. 6a is a terminal pin, 6b is a wire, and forms the terminal of the moving coil 6. The movable coil 6 is, for example, a multilayer air-core coil made by winding a self-fusing wire (an electric wire with a fusing film formed on the outermost layer of the core wire) in a predetermined shape a predetermined number of times, and then energizing this air-core coil to complete the whole process. It can be manufactured by integrating with a fusion film.

Injection molding, for example, is effective as a means for forming the arm 5 and the holding member 9 integral therewith. That is, the movable coil 6, in which the terminal pins 6a are connected to the strands 6b by, for example, soldering, is inserted into an injection mold, and after positioning, a heated melt of a thermoplastic resin containing, for example, carbon fiber is injected. After cooling and solidifying, it can be taken out from the mold. The arm 5 and the movable coil 6 are fixed together via the holding member 9 by the injection molding described above.

FIG. 3 is a longitudinal sectional view of a main part of a moving coil 6 in another embodiment of the present invention. In FIG. 3, 6c is a groove for preventing the movable coil 6 from coming off in the thickness direction, and is formed in advance when the movable coil 6 is wound. By providing the groove 6c in this way, the holding member 9 (FIGS. 1 and 2)
(see) can increase the fixation effect.

With the above configuration, the weight of the arm 5 is significantly reduced compared to that made of conventional aluminum alloy (specific gravity 2.6) (specific gravity of carbon fiber-containing resin 1.4).
~1.6), and the access time can be shortened from 18 msec in the conventional method to 14 msec. The longitudinal elastic modulus of the material forming the arm 5 is 40×1
04 kg/cm2, and 68 kg/cm2 of aluminum alloy
×104 kg/cm2. In addition, since the thickness of the holding member 9 that holds the peripheral edge of the moving coil 6 is formed to be substantially the same as the thickness of the moving coil 6, the magnetic gap can be reduced, thereby increasing the thrust. and can improve responsiveness.

In this embodiment, an actuator for a magnetic head has been described, but the function is the same even if the functional member to be provided at one end of the arm is not only a magnetic head but also an optical head or something else. The type of thermoplastic resin constituting the arm and the holding member can be selected as appropriate by taking into consideration the rigidity, heat resistance, etc. required for the arm and the holding member. polyimide resin,
Known resins (preferably heat-resistant resins) such as polyamide-imide resin and polyester resin may be used. Furthermore, in order to improve the mechanical strength without increasing the weight, it is preferable to use a thermoplastic resin containing a filler having a low specific gravity such as carbon fiber. The amount added is preferably 10 to 50% by weight, more preferably 2% by weight.
It is 0 to 40% by weight.

[0019]

Effects of the Invention Since the present invention has the structure and operation as described above, it has the following effects. (1) The weight of the movable parts, mainly the arm, can be significantly reduced, reducing access time by 20% compared to conventional models.
It can be shortened by more than (2) In relation to (1) above, the power consumption required for driving can be significantly reduced, so it is suitable for use in, for example, a laptop type personal computer. (3) Since the movable parts can be integrally molded, workability is greatly improved and manufacturing costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view of main parts showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a main part showing an embodiment of the present invention.

FIG. 3 is a vertical sectional view of a main part of a moving coil in another embodiment of the present invention.

FIG. 4 is a partially exploded, partially sectional plan view showing an example of a conventional swing-type actuator.

5 is a view taken along arrow A in FIG. 4. FIG.

FIG. 6 is a partially exploded, partially sectional plan view showing another example of a conventional swing-type actuator.

7 is a view taken along arrow B in FIG. 6. FIG.

[Explanation of symbols]

1 York 2. Permanent magnet 5 Arm 6. Moving coil 9 Holding member

Claims (2)

[Claims] Claim 1: A permanent magnet is fixed to at least one of a pair of opposing yokes, and a housing is formed by forming a magnetic gap on the surface of the permanent magnet, a moving coil is fixed to one end, and a functional member is fixed to the other end. In the swing type actuator, the arm is formed to be able to swing freely, and the moving coil is movably disposed within the magnetic gap. 30×1
A rocking actuator characterized in that it is integrally formed of a thermoplastic resin with a weight of 0.4 kg/cm2 or more. 2. The oscillating actuator according to claim 1, wherein the holding member that holds the peripheral edge of the moving coil has a thickness that is substantially the same as the thickness of the moving coil. .