JP2605285Y2 - Swing type actuator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillating actuator such as an actuator for a magnetic disk, and more particularly to an oscillating actuator in which a functional member such as a magnetic head oscillates in an arc trajectory. (Swing type) actuator.

[0002]

2. Description of the Related Art Conventionally, an oscillating or rotary actuator as shown in FIGS. 5 and 6 is used to position a magnetic head on a recording track of a magnetic disk or the like. In both figures, a permanent magnet is fixed to the yoke 1, and the yoke 1 is arranged to face each other with different polarities and assembled by a support column 3 to form a magnetic circuit through a gap 4. An arm 5 has a flat movable coil 6 fixed at one end and a magnetic head (not shown) fixed at the other end.
Are disposed via the shaft 7 so as to be rotatable and swingable so as to be located in the gap 4. When a signal current is applied to the movable coil 6, a driving force around the shaft 7 acts on the movable coil 6 according to Fleming's left-hand rule, causing the arm 5 to rotate and swing, and the magnetic head fixed to the arm 5 to move. It is positioned on a predetermined recording track on the magnetic disk. The rotation direction is switched by reversing the direction of the current flowing through the coil. In the conventional magnetic disk actuator, when the movable coil 6 is fixed to the arm 5, an adhesive is generally used. However, the fixing operation using an adhesive is not only complicated and low in workability, but also has a problem in that the positioning accuracy of the movable coil is insufficient and the reliability is low. In addition, the processing of the end of the movable coil 6 requires complicated work, and there is a problem that the workability of the entire assembling work is reduced.
Further, in the field of recent magnetic disk drives, the demands for downsizing, thinning, high performance, and the like of the drive are becoming more severe, and the positioning accuracy of the movable coil 6 and the improvement of workability and reliability in the bonding operation have been improved. Therefore, the conventional structure has a problem that the above requirement cannot be satisfied. Therefore, it has been proposed to integrate the movable coil 6 with the arm 5 by resin molding (for example, Japanese Patent Application Laid-Open No. 63-99756).
No. 60-159566). With such a configuration, the structure for holding the movable coil 6 is simplified and can be made considerably thinner.
This is advantageous for making the entire actuator compact.

[0003]

However, in the above-mentioned conventional resin molded structure, the mechanical strength, especially the pull-out resistance and the bending strength are insufficient, or the connection between the arm 5 and the movable coil 6 is not sufficient. There is a problem that the fixation is insufficient. In addition, since the movable coil 6 is molded by molding, the resin is also applied to the upper and lower surfaces of the movable coil 6 to increase the thickness dimension, and the gap 4 must be enlarged. Therefore, there is a problem that the magnetic performance of the permanent magnet 2 cannot be sufficiently exhibited, the characteristics as an actuator are reduced, and the thrust is also reduced. Further, as shown in FIG. 2, when the resin molding is performed so that the thickness dimension of the holding member 9 holding the peripheral portion of the movable coil 6 and the thickness dimension of the movable coil 6 are the same, the movable coil 6 becomes There is a problem that the coil easily exits from the coil 9 and, as shown in FIG.
Movable so as to form a concave groove 6b at the center of the outer periphery of
Coils have been proposed. However, this is not realistic considering the mass productivity of the movable coil. here
Now, these problems will be specifically described with reference to the drawings showing the winding configuration of the coil . FIG. 4 is a longitudinal sectional view of a main part of the movable coil 6, and 6C is one side thereof. 7 and 8 are enlarged views of the portion 6C in FIG. 9 and 10 show the movable coil 6 in the 6C portion as shown in FIG.
Of the thickness of the holding member holding the peripheral portion of the movable coil 6
FIG. 2 is an enlarged view of a state in which a resin mold is applied so as to form the same thickness dimension. When mass-producing moving coils by an automatic winding machine at low cost, if the winding start side is the first layer and the second layer, the third layer, and the outermost layer are the Nth layer, the following two types are available. Are known. As shown in FIG. 7, the first winding pattern is a winding method in which the odd-numbered layer and the even-numbered layer have the same number of windings in the first to Nth layers. As shown in FIG. 8, the second winding pattern is a winding method in which the odd-numbered layer has one more turn than the even-numbered layer. And
When resin molding is applied to the same number of windings as shown in FIG. 2 , the holding member 9 does not cover the lower side of the movable coil 6 as shown in FIG. There is a drawback that it easily comes off. Further, even in the case of an odd number of turns, as shown in FIG. 10, there is a problem that if the winding is odd-numbered times, the holding member 9 does not cover the movable coil 6 and the movable coil 6 is easily pulled out when pushed upward. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, is small and thin, prevents the movable coil from falling off, and has a movable coil.
It is an object of the present invention to provide an oscillating actuator in which the fixing strength of the holding member and the holding member is increased .

[0004]

In order to achieve the above object, according to the present invention, a permanent magnet is fixed to at least one of a pair of opposed yokes, and a magnetic gap is formed on the surface of the permanent magnet. And an arm having a movable coil fixed to one end and a functional member fixed to the other end, the arm being oscillatably formed, and the movable coil is movably disposed in the magnetic gap. , winding the outermost peripheral portion of the movable coil, and the winding to be thinner and down relative to the maximum thickness portion of the movable coil, winding of the movable coil becomes a and the movable coil and the arm of a thermoplastic resin top with the injection-molded holding member so as to embrace the periphery including the upper and lower ends of the outer peripheral portion fixed integrally with the movable coil and the arm, the winding outermost periphery of the moving coil
The thickness of the holding member for holding a peripheral portion including the upper and lower ends of the parts to form substantially the same thickness and of the moving coil, adopting the technical means of.

[0005]

According to the above configuration, the strength of fixing the movable coil and the holding member is increased while maintaining the characteristics of being small and thin.
And prevent the moving coil from falling off.
I did it . Furthermore, it can be completely fixed to the arm.
ing. Therefore , the positioning accuracy and reliability of the movable coil can be improved .

[0006]

1 and 2 are a plan view and a longitudinal sectional view, respectively, of an essential part of an embodiment of the present invention. The same parts are designated by the same reference numerals as in FIGS. In both figures, the arm 5 is formed of, for example, an aluminum alloy die-cast, and a mounting hole 8a is formed at an intermediate portion, and a hole 8 for mounting a functional member (not shown) such as a magnetic head is provided at one end.
b on the other end (moving coil 6 side) to prevent protrusion 5a
Are provided integrally. As shown in FIG. 1, the projection 5a forms a projected contour on a plane in a dovetail shape, and
b is provided. Next, reference numeral 9 denotes a holding member, which is made of a thermoplastic resin, and is formed so that the arm 5 and the movable coil member 6 are integrally joined and fixed. That is, it is formed so as to hold the periphery of the movable coil 6 and the periphery of the protrusion 5a. Therefore, the thermoplastic resin is also filled in the through hole 5b provided in the projection 5a, and adheres to the inner surface thereof. The thickness of the holding member 9 for holding the peripheral portion of the movable coil 6 and the thickness of the movable coil 6 are substantially the same. The movable coil 6 is formed, for example, by winding a self-fused electric wire (an electric wire having a fusion coating formed on the outermost layer of the core wire) into a predetermined shape by a predetermined number to form a multilayer air-core coil. It can be manufactured by integrating with a coating film. For example, an injection molding means is effective as an integral fixing means of the arm 5 and the movable coil 6 as described above. That is, an arm 5 which has been die-cast in advance, and a terminal pin (not shown) on the element wire.
Is inserted into a mold for injection molding, positioning is performed, and then a heated melt of a thermoplastic resin such as glass-filled polyphenylene sulfide resin is injected, and cooled and solidified. It can be taken out of the mold. The arm 5 and the movable coil 6 are integrally fixed via the holding member 9 by the injection molding. With the above configuration, the movable coil 6 can be firmly held from the peripheral edge by the holding member 9, and the protrusion 5 a provided on the arm 5 is embedded in the holding member 9, and the holding member 9 is also provided in the through hole 5 b. Is filled, the joining strength between the arm 5 and the movable coil 6 can be improved. That is, the pull-out resistance in the A direction is increased by the dovetail-shaped projections 5a and the through holes 5b, and the bending strength in the B direction can also be improved. 11 and 12
FIG. 3 is a longitudinal sectional view of a main part of the movable coil 6 in the present embodiment. In both figures, the movable coil is wound by an even number of turns, and FIG. 11 shows a case where the outermost periphery is completely wound, and FIG. 12 shows a case where the outermost periphery is not completely wound. In either case, the holding member is
It covers the end face and has the effect of retaining in both up and down directions. The type of the thermoplastic resin constituting the holding member 9 can be appropriately selected in consideration of the rigidity, heat resistance, and the like required for the holding member 9. In addition to the above, for example, polybutylene terephthalate resin, polyamide resin, polyimide A known resin (preferably, a heat-resistant resin) such as a resin, a polyamideimide resin, or a polyester resin may be used. Among these resins, the longitudinal elastic modulus (measurement method: ASTM, D-
638) is 10 × 10 ⁴ kg / cm ² or more (preferably 13 × 10 ⁴ kg / cm ² ).
10 ⁴ kg / cm ² or more) is preferable. In particular, it is preferable to use a liquid crystal polyester resin (a polyester having a rigid straight chain in the main chain), which is a kind of liquid crystal polymer (having liquid crystallinity in a molten state), as the thermoplastic resin. In the above embodiments, the actuator for the magnetic head has been described. However, the function is the same even if the functional member to be provided at one end of the arm is not only the magnetic head but also an optical head or the like. The magnetic circuit may have a structure in which a permanent magnet is fixed to only one of the pair of yokes facing each other.

[0007]

[Effects of the Invention] Since the present invention has the above-described configuration and operation, the fixing strength between the movable coil and the holding member is increased.
And prevent the moving coil from falling off.
be able to. In addition, the positioning accuracy between the arm and the movable coil and the bonding strength can be greatly improved. Since the thickness of the holding member in the movable coil portion is formed to be substantially the same as the thickness of the movable coil, the magnetic gap can be formed small, and thrust and responsiveness can be improved.

[Brief description of the drawings]

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

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

FIG. 3 is a longitudinal sectional view of a main part of a movable coil.

FIG. 4 is a longitudinal sectional view of a main part of a movable coil.

FIG. 5 is a partially broken partial cross-sectional plan view showing an example of a conventional swing type actuator.

6 is a view in the direction of arrow D in FIG. 5;

FIG. 7 is an enlarged view of a main part showing an example of the same number of windings in FIG.

FIG. 8 is an enlarged view of a main part showing an example of a different number of windings in FIG. 4;

9 is an enlarged view of a main part in FIG. 4 which is formed by resin molding according to a conventional example.

FIG. 10 is an enlarged view of a conventional example in which a main part in FIG. 4 is resin-molded.

FIG. 11 is an enlarged view of a main part of FIG. 4 which is formed by resin molding according to the embodiment of the present invention.

FIG. 12 is an enlarged view of a main part of FIG. 4 which is formed by resin molding according to the embodiment of the present invention.

[Explanation of symbols]

 5: Arm 6: Moving coil 5a: Projection 5b: Through hole 9: Holding member

Claims (1)

(57) [Scope of request for utility model registration] A permanent magnet is fixed to at least one of a pair of opposed yokes, a housing having a magnetic gap formed on the surface of the permanent magnet, a movable coil at one end, and a functional member at the other end. And a movable coil is movably disposed in the magnetic gap, the outermost peripheral portion of the winding of the movable coil has a maximum thickness of the movable coil. and winding such that thinner and down relative to part, winding of the movable coil becomes a and the movable coil and the <br/> arm of a thermoplastic resin
With fixed integrally with the movable coil and the arm by injection molding the holding member so as to embrace the periphery including the upper and lower ends of the outermost peripheral portion, on winding the outermost periphery of the moving coil
A swing-type actuator, wherein a thickness dimension of a holding member for holding a peripheral portion including a lower end is substantially equal to a thickness dimension of the movable coil.