JP3271303B2 - 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, that is, an actuator configured so that a functional member such as a magnetic head oscillates in an arc trajectory. In particular, the present invention relates to an oscillating actuator which is improved so as to be thinner and lower in cost.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view of a main part showing an example of a conventional swing type actuator.
(B) shows an arrow A direction in (a). In FIG. 2, reference numeral 1 denotes a yoke, which is formed in a flat plate shape from a ferromagnetic material such as soft iron, for example, and is provided so as to be opposed to a column 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. The magnetic gap 4 is formed.

An arm 5 has a flat movable coil 6 fixed to one end and a functional member (not shown) such as a magnetic head fixed to the other end. The movable coil 6 is formed by the permanent magnet 3. And is rotatably or oscillated via a shaft 7 so as to be positioned within the magnetic gap 4.

When a signal current is applied to the movable coil 6 according to the above configuration, a driving force about the shaft 7 acts on the movable coil 6 according to Fleming's left-hand rule to rotate or swing the arm 5, For example, a magnetic head provided at the other end of the magnetic disk 5 can be positioned at a predetermined recording track on the magnetic disk. The switching of the swing direction is
This is performed by reversing the direction of the current supplied to the movable coil 6.

FIG. 3 is a perspective view showing the main parts of the magnetic circuit shown in FIG. 2 and FIG. 4 is an exploded perspective view showing the structural members in FIG. 3, and the same parts are the same as those in FIG. Indicated by reference numerals. In FIGS. 3 and 4, reference numeral 8 denotes a stopper member, which is provided on the lower yoke 1 and has the structure shown in FIG.
Is formed so as to engage with the arm 5 when the arm 5 is stopped as shown in FIG.
Next, reference numeral 9 denotes a positioning pin, which is provided on the lower yoke 1 and contacts the outer peripheral portion of the permanent magnet 3 so that the permanent magnet 3 can be fixed at a predetermined position.

[0006]

In order to assemble the magnetic circuit as shown in FIG. 3, after assembling the respective constituent members, as shown in FIG. Then, the permanent magnet 3 is fixed to the yoke 1 with an adhesive. In this case, a process of heating and drying to cure the adhesive is required, and the work of fixing the permanent magnet 3 requires time and man-hours, resulting in an increase in cost. Further, when the adhesive is dried by heating, there is a problem that harmful outgas is generated from the adhesive and the environment may be polluted.

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

On the other hand, in recent years, demands for thinning and cost reduction of this type of oscillating type actuator have become increasingly severe, and in the above-mentioned conventional configuration, the number of components is large and the assembly cost is high. Because of the bulk, the above requirements cannot be satisfied.

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

[0010]

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. The movable coil is movable along the surface of the permanent magnet in the magnetic air gap, and comprises a housing formed and an arm formed with a movable coil fixed to one end and a functional member fixed to the other end so as to be swingable. In the swing type actuator configured as described above, an arm support shaft on the substrate,
A holding member and a column located near both sides of the holding member are respectively erected, and a housing is formed by integrally molding these members with a thermoplastic resin material, and magnetized in a thickness direction. A permanent magnet assembly formed by a permanent magnet formed in a flat plate shape and a lower yoke made of a ferromagnetic material adsorbed on the back surface of the permanent magnet is held by the holding member when the housing is formed. Technical means for securing an upper yoke, which is integrally fixed and formed by a ferromagnetic material so that the permanent magnet can be included in a projected profile onto a plane, to the support via a gap with the surface of the permanent magnet. It was adopted.

In the present invention, it is preferable to use a rare-earth permanent magnet having a large coercive force since the operating point cannot be set high because the thickness of the permanent magnet is limited. Further, in recent years, further reduction in thickness and higher performance are required. Therefore, in order to secure a high magnetic flux density in the magnetic gap, R-Fe-B (R: Y, Nd or other rare earth element More preferably, one or more permanent magnets are used.

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, polyamide imide resin and polyester resin (preferably having heat resistance) are used. Having a resin).

Among the above resins, the longitudinal elastic modulus (measuring method:
(ASTM D-638) is preferably 10 × 10 ⁴ kg / cm ² or more (preferably 13 × 10 ⁴ kg / cm ² or more). 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, an aromatic dicarboxylic acid, and an aromatic diol; c)
There are those having various basic compositions, such as a copolymer of poly-p-hydroxybenzoate and naphthoic acid, and those of wholly aromatic (b) and (c) are preferred in terms of strength and elastic modulus, (C) is more preferred. In particular, the wholly aromatic polyester resin (c) has rigid molecular chains oriented in the flow direction at the time of molding, so that not only the longitudinal elastic modulus in that direction is large, but also the vibration absorption characteristics are good and the linear expansion coefficient is high. There is an advantage that it is small (close to a metal material).

When the liquid crystal polymer is molded at a liquid crystal state temperature lower than the complete melting temperature, the fluidity is high and the molding is easy. 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 is kg / cm ² , the same applies hereinafter), C130
(16 × 10 ⁴ ), A230 (30 × 10 ⁴ ), B23
0 (38 × 10 ⁴ ), A410 (21 × 10 ⁴ ), A4
22 (18 × 10 ⁴ ), C400 (17 × 10 ⁴ ), A
540 (16 × 10 ⁴ ) (above Celanese), XYD
AR RC-210 (16.2 × 10 ⁴ ), G-43C (1
6.1 × 10 ⁴ ) (Dartco).

Incidentally, the longitudinal elastic modulus of the steel is 220 × 10 ⁴ ,
Aluminum: 68 × 10 ⁴ , methacrylic resin: 4.2
× 10 ⁴ , polystyrene resin: 3.2 to 3.6 × 10 ⁴ , polyphenylene sulfide resin: 10 × 10 ⁴ (all units are kg / cm ² ), which is larger than using a general thermoplastic resin. Rigidity can be obtained. Further, as the liquid crystal polymer, a material to which a filler such as glass fiber or carbon fiber is added in order to improve mechanical strength and heat resistance can be used. The addition amount is 10
It is desirably 50% by weight, more preferably 20 to 40% by weight.

In the present invention, the above-mentioned thermoplastic resin
Flexural modulus as fat (Measurement method: ASTM D-792)
Is 13 × 10^Fourkg / cm^TwoThese can also be used effectively
You. As such a resin, for example, the aforementioned Vectra A
130 (15 × 10^Four) (Unit is kg / cm^TwoEtc.
), C130 (14 × 10^Four), A230 (29 × 1
0^Four), B230 (36 × 10^Four), A410 (18 ×
10^Four), A422 (17 × 10^Four), A540 (14
× 10^Four), XYDAR RC-210 (13.6 × 1
0 ^Four), G-43C (14.9 × 10^Four), Ryton R
-4 (14 × 10^Four) (Philips Oil), DIC P
PS FZ ・ 1140 (14 × 10^Four) 、 ASAHI ・
PPS RG-40JA (14.4 × 10^Four) (Asahi Glass),
Fortron 1140A1 (13 × 10^Four) (Polyplastic
Styx), GS-40 (15 × 10^Four), G-10
(20 × 10^Four), G-6 (18 × 10^Four), G-4F
(14 × 10 ^Four), FC-5 (16 × 10^Four) (East
Polyphenylene sulphie such as So Sussteel)
And the like.

[0018]

According to the above construction, the number of constituent members can be reduced, and since most of the constituent members are integrally formed, the assembling work is facilitated and the production cost can be greatly reduced. .

[0019]

FIG. 1 is an exploded perspective view showing components of a magnetic circuit according to an embodiment of the present invention, and the same parts are denoted by the same reference numerals as in FIGS. In FIG.
Reference numeral 10 denotes a substrate, which has a support member 2, a stopper member 8, an arm support shaft 16, and a holding member 11 integrally holding a permanent magnet assembly 13 formed as described later integrally formed on a surface thereof. And The above components are integrally protruded, and the permanent magnet assembly 1 is held by the holding member 11.
In order to hold 3 in one piece, an injection mold is used, for example, a heated melt of polyphenylene sulfide resin containing glass fiber is injected into the molding space, and after cooling and solidifying, it is taken out from the molding space. Good. The permanent magnet assembly 13
If it is inserted into a predetermined location in the injection molding die before molding, the holding member 11 is formed by injection of the heated melt, and at the same time, the permanent magnet assembly 13 is held and fixed by the holding member 11. Is done.

Next, the permanent magnet 3 constituting the permanent magnet assembly 13 is formed in a substantially fan-shaped flat plate shape using, for example, an Nd-Fe-B-based magnet material, magnetized in the thickness direction, and N, S on the surface.
It is configured so that a magnetic pole appears. When manufacturing such a permanent magnet 3, two permanent magnets may be joined together at 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 form a permanent magnet. The magnet assembly 13 is constituted.

Reference numeral 14 denotes an upper yoke, which is formed in the shape of a pseudo-triangular plate using the same ferromagnetic material as the lower yoke, and has a mounting hole 15 at an end. The upper yoke 14
Are formed such that the permanent magnet 3 can be included in a contour projected on a plane. 2a is a set screw.

With the above configuration, when assembling the magnetic circuit, the components are integrally protruded, and the permanent magnet assembly 13 is integrally held and fixed in the holding member 11 on the support column 2 of the substrate 10. The upper yoke 14 may be placed and fixed with the set screw 2a.

In this embodiment, an example is described in which the peripheral edge of the holding member 11 integrally projecting from the substrate 10 is formed continuously. Is the same, that is, the permanent magnet assembly 1
It is only necessary to have a function capable of holding and fixing 3. As means for fixing the upper yoke 14 to the column 2, the set screw 2
Not only a but also a rivet-shaped thing may be driven or press-fitted and fastened. Furthermore, in the present embodiment, the actuator for the magnetic head has been described, but the functional members to be provided at one end of the arm include:
The operation is the same for not only a magnetic head but also an optical head and other devices.

The arm support shaft 16 is not limited to an example integrally formed with the substrate 10 by a thermoplastic resin material, but may be formed by a steel material, for example, and may be insert-molded when the substrate 10 is formed. When the arm is interposed, a bearing may be used together.

[0025]

Since the present invention has the above-described structure and operation, by molding most of the components of the magnetic circuit integrally, the number of components can be greatly reduced, and the assembling work can be performed. As a result, the productivity can be greatly improved, and as a result, the production cost can be significantly reduced. Further, by integrating most of the constituent members, there is an effect that the size and thickness of the entire swing type actuator can be reduced.

[Brief description of the drawings]

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

FIGS. 2A and 2B are explanatory views of a main part showing an example of a conventional oscillating actuator, wherein FIG. 2A is a partially crushed plane, and FIG.

FIG. 3 is a perspective view of a main part showing constituent members of a magnetic circuit in FIG. 2;

FIG. 4 is an exploded perspective view showing constituent members in FIG. 3;

[Explanation of symbols]

 2 Support 3 Permanent magnet 10 Substrate 11 Holding member 14 Upper yoke 16 Arm support shaft

Claims (1)

(57) [Claims] 1. A housing in which a permanent magnet is fixed to at least one of a pair of yokes provided facing each other, a magnetic gap is formed on the surface of the permanent magnet, a movable coil is provided at one end, and a functional member is provided at the other end. A movable arm is formed along the surface of the permanent magnet in the magnetic gap, and an arm support shaft is provided on the substrate. A holding member and a column located near both sides of the holding member are respectively erected, and a housing is formed by integrally molding these members with a thermoplastic resin material, and magnetized in a thickness direction. A permanent magnet assembly formed by a permanent magnet formed in a flat plate shape and a lower yoke made of a ferromagnetic material adsorbed on the back surface of the permanent magnet is moved forward during molding of the housing. An upper yoke which is integrally fixed to be held by a holding member and is formed of a ferromagnetic material so that the permanent magnet can be included in a contour projected onto a plane; An oscillating-type actuator, wherein the oscillating-type actuator is fixed to a surface.