JP2672920B2 - 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 portion. 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 swing-type actuator configured as described above, the holding member and the columns located near both sides of the holding member are erected on the substrate, and at least the substrate, the holding member, and the columns are integrally formed of a thermoplastic resin material. To form a housing, which is magnetized in the thickness direction to form a flat magnet, and a lower yoke made of a ferromagnetic material that is attracted to the back surface of the permanent magnet. A permanent magnet assembly formed me,
An upper yoke fixedly press-fitted in the holding member and formed by a ferromagnetic material so that the permanent magnet can be included in a projected contour on a plane is fixed to the column through a gap with the surface of the permanent magnet. I adopted the technical means.

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

[0019]

FIG. 1 is an exploded perspective view showing the components of 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.
Reference numeral 10 denotes a substrate, on the surface of which the pillar 2, the stopper member 8 and the holding member 11 are integrally projected to form a housing. In order to integrally project these constituent members on the substrate 10, an injection molding die is used, and for example, a heating melt of a polyphenylene sulfide resin containing glass fibers is injected into the molding space, and then cooled and solidified. It may be taken out from the post-molding space. It is preferable that the inner contour dimension of the holding member 11 is slightly smaller than the outer contour dimension of the permanent magnet 3.

Next, the permanent magnet 3 is, for example, Nd-Fe-B.
The magnetic material is formed into a substantially fan-shaped flat plate, magnetized in the thickness direction, and N and S magnetic poles are formed on the surface.
When manufacturing such a permanent magnet 3, two permanent magnets may be joined together by a broken line portion to be integrated. Reference numeral 12 denotes a lower yoke, which 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 attached to the permanent magnet assembly 13. Make up.

Reference numeral 14 denotes an upper yoke, which is formed of a ferromagnetic material similar to that of the lower yoke 12 into a pseudo-triangular flat plate shape, and a mounting hole 15 is provided at an end thereof. Upper yoke 1
4 is formed so that the permanent magnet 3 can be included in the contour projected onto the plane. 2a is a set screw.

When assembling a magnetic circuit with the above-described structure, first, the magnet assembly 13 is press-fitted and fixed in the holding member 11 integrally provided on the substrate 10. In this case the holding member 1
The inner contour dimension of 1 is formed slightly smaller than the outer contour dimension of the permanent magnet 3 as described above, but the holding member 11
Since it is made of glass fiber-containing polyphenylene sulfide resin, it has flexibility and elasticity and can be press-fitted and fixed in the holding member 11 by pressing the permanent magnet assembly 13 from above. is there. Then, the upper yoke 14 is placed on the column 2 and fixed by the set screw 2a.

In the present embodiment, an example was described in which the peripheral edge of the holding member 11 that integrally projects on the substrate 10 is formed continuously, but it may also be formed discontinuously or in the form of a plurality of protrusions. Are the same, in short, the permanent magnet assembly 1
It suffices to have a function capable of holding and fixing 3. Further, as a means for fixing the upper yoke 14 to the column 2, a set screw 2
Not only a, but also a rivet-like object may be driven in or press-fitted for fastening. Further, in the present embodiment, the actuator for the magnetic head is described, but the functional member to be provided at one end of the arm is
The operation is the same not only for the magnetic head but also for an optical head and others.

[0024]

Since the present invention has the structure and operation as described above, the number of the constituent members can be greatly reduced by integrally molding most of the constituent members of the magnetic circuit. As a result, the productivity can be significantly improved, and as a result, the manufacturing cost can be significantly reduced. 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 an exploded perspective view showing constituent members of 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 12 Lower yoke 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 holding member and a holding member on the substrate, in which the movable coil is configured to be movable along the surface of the permanent magnet in the magnetic gap. Stands are provided in the vicinity of both sides of the member, and at least the substrate, the holding member, and the support are integrally molded of a thermoplastic resin material to form a housing, which is magnetized in the thickness direction to form a flat plate. A permanent magnet formed on
A permanent magnet assembly formed by a lower yoke made of a ferromagnetic material adsorbed on the back surface of the permanent magnet is press-fitted and fixed in the holding member, and the permanent magnet causes the permanent magnet to fall within a contour projected on a plane. An oscillating actuator characterized in that an upper yoke formed so as to be included is fixed to the pillar through a gap from the surface of a permanent magnet.