JP2672921B2 - Oscillating 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, that is, an actuator configured such that a functional member such as a magnetic head oscillates so as to draw an arc locus. In particular, the present invention relates to an oscillating actuator improved so as to be thin and low cost.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view of a main part showing an example of a conventional rocking type actuator, in which (a) is a partially crushed plane,
(B) shows the arrow direction A in (a). In FIG. 2, reference numeral 1 denotes a yoke, which is formed of a ferromagnetic material such as soft iron into a flat plate shape, and is provided so as to face each other via a pillar 2 provided at an end. Reference numeral 3 denotes a permanent magnet, which is formed in a substantially trapezoidal flat plate shape, is magnetized in the thickness direction, and is fixed to the surface of the lower yoke 1 so that N and S magnetic poles appear on the surface, and the magnet is attached to the surface. A magnetic gap 4 is formed.

Reference numeral 5 denotes an arm, one end of which is fixed with a flat movable coil 6 and the other end of which is fixed with a functional member (not shown) such as a magnetic head. The movable coil 6 is formed by the permanent magnet 3. It is disposed so as to be rotatable or swingable via a shaft 7 so as to be positioned inside the magnetic gap 4.

When a signal current is applied to the movable coil 6 with the above-described structure, 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 or swing to move. For example, a magnetic head provided at the other end of 5 can be positioned on a predetermined recording track on the magnetic disk. The swing direction can be changed by
This is performed by reversing the direction of the current supplied to the movable coil 6.

FIG. 3 is a perspective view of the essential parts showing the constituent members of the magnetic circuit shown in FIG. 2, and FIG. 4 is an exploded perspective view showing the constituent members of FIG. 3, with the same parts referring to the same parts as in FIG. It shows with a code. In FIGS. 3 and 4, 8 is a stopper member, which is provided on the lower yoke 1,
When the arm 5 is stopped, the arm 5 is formed so as to engage with the arm 5 to prevent undesired swinging of the arm 5.
Next, 9 is a positioning pin, which is provided on the lower yoke 1 and is brought into contact with the outer peripheral portion of the permanent magnet 3 so that the permanent magnet 3 can be fixed at a predetermined position.

[0006]

In the case of assembling the magnetic circuit as shown in FIG. 3, after processing the respective constituent members, as shown in FIG. 4, first, the positioning pin 9 is mounted at a predetermined position. , The permanent magnet 3 is fixed to the yoke 1 with an adhesive. In this case, a treatment of heating and drying is required to cure the adhesive, and the fixing work of the permanent magnet 3 requires time and man-hours, resulting in a problem of high cost. Further, when the adhesive is dried by heating, harmful outgas may be generated from the adhesive, which may pollute the environment.

Next, after the permanent magnet 3 is fixed to the yoke 1, the support 2 and the stopper member 8 are fixed, the upper yoke 1 is mounted on the support 2, and the set screw 2a is used to fix them. Since the fixing means of the members is screwing and / or caulking, the ratio of manual work is high.
Therefore, time and man-hours are increased, which causes a high cost.

On the other hand, in recent years, demands for thinning and cost reduction of this type of oscillating actuator have become increasingly strict, and in the above-mentioned conventional structure, the number of constituent members is large and the assembling cost is high. Since it is bulky, the above requirements cannot be satisfied.

The present invention solves the above-mentioned problems existing in the prior art, and provides an oscillating actuator which has a small number of constituent members, is easy to assemble, and can significantly reduce the manufacturing cost. The purpose is to do.

[0010]

In order to achieve the above object, in the present invention, a permanent magnet is fixed to at least one of a pair of yokes provided facing each other, and a magnetic gap is formed on the surface of the permanent magnet. It is composed of a housing formed and an arm swingably formed by fixing a movable coil at one end and a functional member at the other end, and the movable coil is movable along the surface of the permanent magnet in the magnetic gap. In the oscillating actuator configured as described above, a permanent magnet assembly formed by a permanent magnet magnetized in the thickness direction and formed in a flat plate shape, and a lower yoke made of a ferromagnetic material attracted to the back surface of the permanent magnet. A three-dimensional body and an upper yoke formed by a ferromagnetic material so that the permanent magnet can be included in a projected contour on a plane are provided with a gap between them when molding a housing made of a thermoplastic resin material. Employing the technical means that are secured together in a housing.

In the present invention, since the permanent magnet as a constituent member has a limited thickness, it cannot have a high operating point. Therefore, it is preferable to use a rare earth magnet having a large coercive force. Further, in recent years, since further thinning and higher performance are required, in order to secure a high magnetic flux density in the magnetic gap, R-Fe-B-based (R: Y, Nd, etc. rare earth element It is more preferable to use one or more permanent magnets.

Next, as the thermoplastic resin material in the present invention, for example, known resins such as polyphenylene sulfide resin, polybutylene terephthalate resin, polyamide resin, polyimide resin, polyamideimide resin, polyester resin (preferably heat resistance Resin) can be used.

Among the above resins, the longitudinal elastic modulus (measurement method:
Those having an ASTM D-638) of 10 × 10 ⁴ kg / cm ² or more (preferably 13 × 10 ⁴ kg / cm ² or more) are preferable. In particular, it is preferable to use, as the thermoplastic resin, a liquid crystalline polyester resin (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).

The liquid crystalline polyester resin includes (a) a copolymer of parahydroxybenzoic acid and polyethylene terephthalate, (b) a copolymer of poly-p-hydroxybenzoate and an aromatic dicarboxylic acid, and an aromatic diol, ( c)
Although there are those having various basic compositions such as copolymers of poly-p-hydroxybenzoate and naphthoic acid, wholly aromatic compounds (b) and (c) are preferable in terms of strength and elastic modulus, The thing of (c) is more preferable. In particular, in the wholly aromatic polyester resin (c), since the rigid molecular chains are oriented in the flow direction during molding, the longitudinal elastic modulus in that direction is large, and in addition, it has good vibration absorption characteristics and a linear expansion coefficient. It has the advantage of being small (close to a metallic material).

When a liquid crystal polymer is molded at a liquid crystal state temperature lower than the complete melting temperature, it has high fluidity and facilitates molding. Particularly, the longitudinal elastic modulus (tensile elastic modulus) is 16 × 10 ⁴ kg /
It is preferable to use a liquid crystal polymer of cm ² or more. A specific example of such a liquid crystal polymer is Vectra A130 (1) which is a wholly aromatic thermotropic liquid crystalline polyester.
8 × 10 ⁴ ) (Unit: kg / cm ² , the same applies below), C130
(16 × 10 ⁴ ), A230 (30 × 10 ⁴ ), B23
0 (38 x 10 ⁴ ), A410 (21 x 10 ⁴ ), A4
22 (18 × 10 ⁴ ), C400 (17 × 10 ⁴ ), A
540 (16 x 10 ⁴ ) (above Celanese), XYD
AR RC-210 (16.2 x 10 ⁴ ), G-43C (1
6.1 × 10 ⁴ ) (above Dartco) and the like.

Incidentally, the longitudinal elastic modulus is steel: 220 × 10 ⁴ ,
Aluminum: 68 × 10 ⁴ , methacrylic resin: 4.2
X10 ⁴ , polystyrene resin: 3.2 to 3.6 x 10 ⁴ , polyphenylene sulfide resin: 10 x 10 ⁴ (both units are kg / cm ² ), which is larger than the use of ordinary thermoplastic resins. The rigidity can be obtained. Further, as the liquid crystal polymer, in order to improve mechanical strength, heat resistance and the like, one to which a filler such as glass fiber or carbon fiber is added can be used. Addition amount is 10
50% by weight is desirable, and more preferably 20-40% by weight.

Further, in the present invention, the above-mentioned thermoplastic resin is used.
Flexural modulus as fat (Measurement method: ASTM D-792)
Is 13 × 10^Fourkg / cm^TwoThe above can also be used effectively
You. Examples of such a resin include the above-mentioned Vectra A.
130 (15 x 10^Four) (Unit is kg / cm^Two, The same below
), C130 (14 x 10)^Four), A230 (29 x 1
0^Four), B230 (36 × 10^Four), A410 (18 x
10^Four), A422 (17 × 10^Four), A540 (14
× 10^Four), XYDAR RC-210 (13.6 × 1)
0 ^Four), G-43C (14.9 × 10^Four) And Ryton R
-4 (14 x 10^Four) (Phillips Oil), DIC / P
PS FZ-1140 (14 x 10^Four), ASAHI
PPS RG-40JA (14.4 x 10^Four) (Asahi Glass),
Fortron 1140A1 (13 x 10^Four) (Polyplastic
Sticks), GS-40 (15 x 10)^Four), G-10
(20 x 10^Four), G-6 (18 × 10^Four), G-4F
(14 x 10 ^Four), FC-5 (16 × 10^Four) (Above East
Saw Sustil) and other polyphenylene sulphies
Do and the like.

[0018]

With the above structure, the number of constituent members can be reduced, and since the constituent members are integrally molded, the assembling work is facilitated and the manufacturing cost can be greatly reduced.

[0019]

1 is a partially fragmented perspective view showing a magnetic circuit according to an embodiment of the present invention, and the same parts are designated by the same reference numerals as those in FIGS. In FIG. 1, 10 is a substrate,
Reference numeral 12 is a lid member, which is integrally formed by the pillar 2.
Make up the housing. A holding member 11 that integrally holds a stopper member 8 and a permanent magnet assembly 13 formed as will be described later is integrally provided on the substrate 10 so as to project. An upper yoke 14 formed as described later is integrally provided on the lower surface of the lid member 12.

To form the housing as described above,
It suffices to use a mold for injection molding, inject a heated melt of a polyphenylene sulfide resin containing glass fibers into the molding space, cool and solidify, and then take out from the molding space.
Note that, if the permanent magnet assembly 13 and the upper yoke 14 are inserted into predetermined positions in the injection molding die before molding, the holding member 11 and the lid member 12 are formed by the injection of the above-mentioned heated melt. At the same time, the permanent magnet assembly 13
And the upper yoke 14 is integrated respectively.

Next, the permanent magnet 3 which constitutes the permanent magnet assembly 13 is formed into a substantially fan-shaped flat plate shape by using, for example, an Nd-Fe-B type magnet material, magnetized in the thickness direction, and N, S is formed on the surface.
It is configured so that the magnetic pole appears. When manufacturing such a permanent magnet 3, two permanent magnets may be joined together by a broken line portion to be integrated. Next, a lower yoke (not shown) is formed of a ferromagnetic material such as soft iron into a flat plate shape having an outer contour corresponding to the outer contour of the permanent magnet 3, and is attracted to the back surface of the permanent magnet 3 to be permanently attached. The magnet assembly 13 is configured. The upper yoke 14 is formed of a ferromagnetic material similar to that of the lower yoke in the shape of a substantially fan-shaped flat plate so that the permanent magnet 3 can be included in the contour projected onto the plane.

With the above structure, the respective constituent members can be integrally formed by the step of only injecting the heated melt into the injection molding die. In this embodiment,
Although the example in which the peripheral edge of the holding member 11 integrally projecting on the substrate 10 is continuously formed has been described, the same effect can be obtained even if it is formed in a discontinuous shape or a plurality of protruding shapes. It suffices to have a function of holding and fixing the solid body 13. Further, although the actuator for the magnetic head has been described in the present embodiment, the functional member to be provided at one end of the arm is not limited to the magnetic head, but the optical head or the like has the same operation.

[0023]

Since the present invention has the structure and operation as described above, the number of constituent members can be greatly reduced by integrally molding the constituent members of the magnetic circuit.
Assembling work is facilitated, and productivity can be significantly improved, resulting in a significant reduction in manufacturing cost. Furthermore, by integrating most of the constituent members, there is an effect that the oscillation type actuator as a whole can be made smaller and thinner.

[Brief description of the drawings]

FIG. 1 is a partially fragmented perspective view showing a magnetic circuit according to an embodiment of the present invention.

2A and 2B are explanatory views of a main part showing an example of a conventional swing-type actuator, in which FIG. 2A is a partially crushed plane, and FIG. 2B is a view in the direction A in FIG.

FIG. 3 is a perspective view of relevant parts showing constituent members of the magnetic circuit in FIG.

FIG. 4 is a perspective view showing the constituent members in FIG. 3 in an exploded manner.

[Explanation of symbols]

 2 Supports 3 Permanent magnets 10 Substrate 11 Holding member 14 Upper yoke

Claims (1)

(57) [Claims] 1. A housing in which a permanent magnet is fixed to at least one of a pair of yokes facing each other, and a magnetic gap is formed on the surface of the permanent magnet, and a movable coil is provided at one end and a functional member is provided at the other end. And a movable arm that is movable along the surface of the permanent magnet in the magnetic gap, and is magnetized in the thickness direction. And a permanent magnet formed in a flat plate shape,
A permanent magnet assembly formed by a lower yoke made of a ferromagnetic material adsorbed on the back surface of the permanent magnet, and an upper yoke formed by the ferromagnetic material so that the permanent magnet can be included in a projected contour on a plane. An oscillating type actuator characterized in that and are integrally fixed in the housing through a gap when the housing made of a thermoplastic resin material is molded.