JP3269705B2 - 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 in which a functional member such as a magnetic head oscillates in a circular locus. In particular, the present invention relates to an oscillating type actuator which is improved so as to ensure a locking operation when not operating.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of a main part showing an example of a conventional oscillating type actuator.
(B) shows an arrow A direction in (a). In FIG. 5, 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 via a support 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.

[0005]

When the above-mentioned actuator is not operated, it is necessary to lock the arm, and there has conventionally been provided a mechanical lock mechanism.
However, it is necessary to mount an extra member for performing such mechanical locking, and it is often not satisfactory in terms of life and reliability. For this reason, by using a part of the driving permanent magnet or separately providing the locking permanent magnet, a magnetic attraction force acts between the movable coil and the locking piece made of a ferromagnetic material. Means for locking by locking (for example, Japanese Patent Publication No. 63-4811)
No. 0).

The above-mentioned magnetic attraction force, that is, the holding force is:
When the movable coil is located in the latch zone (evacuation zone), it is large (for example, 15 g · cm or more), and in the data zone, it is small (for example, 1.5 g · cm) for smooth operation of the movable coil. The following are required.
However, there is a problem that such a demand cannot be satisfied with the above-described conventional device.

In other words, if the holding force is made large, there is an advantage that the arm can be securely locked when the actuator is not operated, but it hinders the operation of the movable coil in the data zone. Is reduced, the operation of the moving coil in the data zone is facilitated, but the locking action of the arm becomes uncertain and there is a reciprocal action.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and provides an oscillating actuator capable of reliably locking an arm when not operating and smoothly operating a movable coil in a data zone. It is intended to provide.

[0009]

In order to achieve the above object, in the present invention, a permanent magnet is fixed to one of a pair of opposed yokes, and a magnetic gap is formed on the surface of the permanent magnet. And a swingable arm having a movable coil fixed to one end and a functional member fixed to 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 to lock the arm when it is not actuated, the permanent magnet is magnetized in the thickness direction and formed into a flat plate shape, and a block-shaped end is formed on the side on which the locking operation is performed. A thickness of the end face on the side where the arm of the projection swings has substantially the same shape as the end face and is smaller than a thickness dimension along the swing direction of the arm of the projection. Dimensions A shield yoke made of a ferromagnetic material in the form of a lock, a locking piece made of a ferromagnetic material provided at a position corresponding to the protruding portion of the movable coil, and connecting a pair of yokes via a support. Tactics were 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, the arm in the present invention is made of a non-magnetic material, but is preferably made of a thermoplastic resin material in order to incorporate the movable coil integrally. As such a thermoplastic resin material,
For example, known resins (preferably resins having heat resistance) such as polyphenylene sulfide resin, polybutylene terephthalate resin, polyamide resin, polyimide resin, polyamide imide resin, and polyester resin can be used.

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).

[0013]

According to the above construction, between the block-shaped projection provided at the end on the side on which the permanent magnet is locked when it is not operated, and the locking piece made of a ferromagnetic material provided on the movable coil. The movable coil, that is, the arm can be reliably locked by the magnetic attraction force acting on the armature. In addition, when the movable coil is operated, the locking piece takes a position away from the protruding portion, so that the magnetic attractive force does not act and does not affect the swing of the movable coil, that is, the arm.

[0014]

FIG. 1 is a partial cross-sectional plan view showing a main part of a magnetic circuit according to an embodiment of the present invention. FIG. 2 is a view taken along arrow B in FIG. Are indicated by reference numerals. 1 and 2, the permanent magnet 3 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 and S magnetic poles appear on the surface. I do. When manufacturing such a permanent magnet 3, two permanent magnets may be joined together at a broken line portion to be integrated.

One end of the permanent magnet 3 on the column 2 side,
That is, a block-shaped projection 8 is integrally provided at the end where the locking operation is performed, and the side of the arm (not shown) of the projection 8 swinging, that is, the right end face in FIG. A shield yoke 9 formed of a flat ferromagnetic material is provided. Note that the shield yoke 9 has substantially the same shape as the right end face of the upper protruding portion 8 and is smaller than the thickness dimension in the swinging direction of the arm of the protruding portion 8, for example, the direction along the outer peripheral edge of the permanent magnet 3. It is formed in a block shape having a thickness dimension. In this case, the shield yoke 9
The magnet can be attracted and held by the magnetic attraction of the permanent magnet 3, but an adhesive may be used in combination.

Next, when assembling the magnetic circuit, the yoke 1 to which the permanent magnet 3 is fixed as shown in FIGS.
Then, the column 2 as shown in FIG. 5 is fixed, another yoke 1 is interposed, and the column 2 is fixed with a set screw (not shown).

Next, FIG. 3 is a plan view showing the arm 5 in the embodiment of the present invention, and the same parts are denoted by the same reference numerals as in FIG. In FIG. 3, reference numeral 7a denotes a hole through which the shaft 7 in FIG. 5 is inserted. Reference numeral 10 denotes a locking piece, which is provided at one side end of the movable coil 6 and at a portion corresponding to the protruding portion 8 shown in FIGS. The locking piece 10 is preferably made of a ferromagnetic material such as soft iron, and is preferably provided integrally with the arm 5. In this case, the arm 5 is formed of, for example, a polyphenylene sulfide resin containing glass fiber.
And it can be integrally formed with the locking piece 10.

By assembling the magnetic circuit and the arm having the above configuration as shown in FIG. 5, a swing type actuator can be formed. The result of evaluating the locking characteristics of the arm 5 with respect to this swing type actuator will be described.

FIG. 4 is a diagram showing the relationship between the arm angle and the torque in the embodiment of the present invention. 4, the position at the arm angle of 0 ° indicates a case where the movable coil 6 of the arm 5 shown in FIG. 3 is located at the S-pole side end of the permanent magnet 3 shown in FIG. In this position, the locking piece 10 shown in FIG. 3 is opposed to the protrusion 8 shown in FIG. Therefore, the locking piece 10 is in the magnetic field of the projection 8 and is attracted to the projection 8, so that the arm 5 is locked.

In FIG. 4, curves a and b respectively correspond to the case where the shield yoke 9 shown in FIGS. 1 and 2 is omitted and the case where the shield yoke 9 is mounted. In this case, the torque represents a torque required to swing the arm 5 in the horizontal direction when the arm 5 shown in FIG. 3 is at the position of the arm angle shown on the horizontal axis. First, as shown by the curve a, in the case where the shield yoke 9 shown in FIGS. 1 and 2 is omitted, the torque at the arm angle of 0 ° is 25 g.
· Cm or more, which is sufficient for the locking action of the arm 5, but the torque value still shows 3 g · cm in the data zone when the arm 5 swings beyond 3.6 °. As described above, if the torque in the data zone is large, the swing of the arm 5 is hindered. Therefore, the data zone is required to have a torque of 1.5 g · cm or less as described above.

On the other hand, the one shown by the curve b has the shield yoke 9 provided on the protruding portion 8 as shown in FIGS. 1 and 2, so that the magnetic field acting on the locking piece 10 shown in FIG. As a result, as shown in FIG. 4, at a position where the arm angle is 0 °, the torque is reduced to slightly more than 20 g · cm. However, since this torque value is sufficiently higher than 15 g · cm required for locking the arm 5, it is a value that can sufficiently satisfy the demand. When the arm 5 swings and exceeds the arm angle of 3.6 °, which is the boundary between the latch zone and the data zone, the torque value is greatly reduced to less than 1 g · cm. Therefore, the arm 5 can swing smoothly.

In the present invention, the shape and size of the shield yoke 9 shown in FIGS. 1 and 2 are appropriately adjusted in accordance with the shape, size and magnetic characteristics of the permanent magnet 3 and the projection 8 constituting the oscillating type actuator to be applied. Can be selected as
If the thickness dimension is too large, the torque value at the locking position, that is, the position at the arm angle of 0 ° is reduced, and a negative torque is generated in the data zone, which is not preferable.

In this embodiment, an example has been described in which a set screw is used as a means for fixing the yokes 1 and 1 via the columns 2, but not only the set screw but also, for example, a rivet-shaped one is driven or press-fitted. It may be fastened.

[0024]

Since the present invention has the above-described configuration and operation, when the swing type actuator is not operated, a block-shaped projection provided at the end on the side where the permanent magnet is locked is provided. The movable coil, that is, the arm can be securely locked by the magnetic attraction force acting between the movable coil and the locking piece provided on the movable coil. Also, when the movable coil is activated, the locking piece takes a position away from the protruding portion, so that the magnetic attraction does not act, and does not affect the swing of the movable coil, that is, the arm at all. There is an effect that the swing can be smoothly performed.

[Brief description of the drawings]

FIG. 1 is a partial sectional plan view showing a main part of a magnetic circuit according to an embodiment of the present invention.

FIG. 2 is a view in the direction of arrow B in FIG.

FIG. 3 is a plan view showing an arm according to the embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between an arm angle and a torque in the embodiment of the present invention.

5A and 5B are explanatory views of a main part showing an example of a conventional rocking type actuator, wherein FIG. 5A is a partially broken plane, and FIG. 5B is a view in the direction of arrow A in FIG.

[Explanation of symbols]

 2 Support 3 Permanent magnet 8 Projection 9 Shield yoke 10 Locking piece

Continuation of the front page (72) Inventor Hiroyuki Kagaya 1-7 Yukitani Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd. (56) References JP-A-3-277160 (JP, A) JP-A-5-18278 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02K 33/18 G11B 21/02

Claims (1)

(57) [Claims] 1. A housing in which a permanent magnet is fixed to one of a pair of yokes provided to face 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. The movable coil is configured to be movable along the surface of the permanent magnet within the magnetic gap, and the arm is configured to lock the arm when inoperative. In the dynamic actuator, a permanent magnet is magnetized in the thickness direction and formed in a flat plate shape, and a block-shaped protrusion is provided at an end on a side where a locking operation is performed. The end face is provided with a shield yoke made of a block-shaped ferromagnetic material having substantially the same shape as the end face and having a thickness smaller than a thickness along a swing direction of the arm of the protrusion, and is movable. Koi The locking piece and the projecting portion made of ferromagnetic material into the corresponding sites provided, oscillating actuator, characterized in that a pair of yokes are linked through an struts.