JPH07143721A - Rocking actuator - Google Patents

Abstract

PURPOSE:To surely couple an arm by a method wherein a chip which is installed on the edge of a permanent magnet on a side performing a rocking movement and which is composed of a ferromgnetic substance is installed and a coupling piece which is installed in a moving coil and which is composed of a ferromagnetic substance is installed. CONSTITUTION:A chip 8 which is composed of a ferromagnetic substance such as soft iron is installed integrally on the edge of a permanent magnet on a side peroforming a rocking movement. A coupling piece 9 is composed of a ferromagnetic substance, and it is installed at the side end part on one side of a moving coil 6 and in a part which is faced with the ferromagnetic-substance chip 8 in a rocking state. In addition, it is preferable that the coupling piece 9 is installed integrally with an arm 5. In this case, the arm 5 is formed of, e.g. a polyphenylene sulfide resin containing a glass fiber, and it is molded integrally with the moving coil 6 and the coupling piece 9 by an injection molding means. Consequently, the coupling piece 9 is situated near the magnetic file of the ferromagnetic-substance chip 8, and it is attracted to the ferromagnetic-substance chip 8. As a result, the arm 5 is coupled.

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 constructed such that a functional member such as a magnetic head oscillates along an arc locus. In particular, the present invention relates to an oscillating actuator improved so as to ensure a locking action when not operating.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of a main portion of 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. 4, reference numeral 1 denotes a yoke, which is formed on a flat plate by a ferromagnetic material such as soft iron, and is provided so as to face each other via a pillar 2 provided at an end portion. 3 is a permanent magnet, which is formed on a substantially trapezoidal flat plate, 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,
A magnetic gap 4 is formed on the surface.

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. In addition, switching of the swing direction is
This is performed by reversing the direction of the current supplied to the movable coil 6.

[0005]

It is necessary to lock the arm when the above-mentioned actuator is inoperative, and there have been conventionally provided mechanical lock mechanisms.
However, since it is necessary to mount an extra member for mechanically locking them, the cost is high and the life and reliability are often unsatisfactory. Therefore, a part of the driving permanent magnet is used, or a locking permanent magnet is separately provided, so that a magnetic attraction force is exerted between the driving permanent magnet and the locking piece made of a ferromagnetic material provided on the movable coil. A means for locking them has been proposed. (See, for example, Japanese Patent Publication No. 63-48110)

The above-mentioned magnetic attraction force, that is, the holding force, is
It is large when the moving coil is located in the latch zone (retraction zone) (for example, 15 g · cm or more), and small in the data zone for smooth operation of the moving coil (for example, 1.5 g · cm). The following) is required.
However, the above-mentioned conventional device has a problem that such requirements cannot be satisfied.

That is, if a large holding force is formed, there is an advantage that the arm can be reliably locked when the actuator is not operated, but the operation of the moving coil in the data zone is hindered. If the value of (1) 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 are reciprocal actions.

The present invention solves the above-mentioned problems existing in the prior art, ensures the locking action of the arm when it is not operated, and is an inexpensive rocking type that can smoothly operate the moving coil in the data zone. The purpose is to provide an actuator.

[0009]

In order to achieve the above-mentioned object, in the present invention, a permanent magnet is fixed to one of a pair of yokes provided facing each other, and a magnetic gap is formed on the surface of the permanent magnet. And a movable coil at one end and a functional member at the other end, which are swingably formed. The movable coil is movable along the surface of the permanent magnet in the magnetic gap. In addition, in the swing-type actuator configured to lock the arm when not operating, the permanent magnet is magnetized in the thickness direction and the length of the permanent magnet in the direction perpendicular to the arc locus of the movable coil is The movable coil is formed so as to be elongated from the center to the outer end of the operating range, and a tip made of a ferromagnetic material is provided on the end face of the outer end of the permanent magnet on the locking side. And employing the technical means of providing the engaging piece to the site of moving coil corresponding to the end face made of a ferromagnetic material.

In the present invention, since the permanent magnet as a constituent member has a limited thickness, its operating point cannot be set high, so that a rare earth magnet having a large coercive force is preferably used. 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, the arm in the present invention is made of a non-magnetic material, but it is preferable to be made of an organic polymer such as a thermoplastic resin material in order to integrally incorporate the movable coil. As such a thermoplastic resin material, for example, a known resin (preferably a resin having heat resistance) such as polyphenylene sulfide resin, polybutylene terephthalate resin, polyamide resin, polyimide resin, polyamideimide resin, polyester resin is used. be able to.

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 (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 (which exhibits crystallinity in a molten state).

[0013]

With the above construction, between the chip made of a ferromagnetic material provided on the end face of the permanent magnet on the side where the lock operation is performed when the device is not operating, and the locking piece made of a ferromagnetic material provided in the movable coil. The movable magnetic coil, that is, the arm can be reliably locked by the magnetic attraction force that acts. Further, when the movable coil is operated, since the locking piece is located away from the end face of the permanent magnet, the magnetic attraction force does not act and has no influence on the swing of the movable coil, that is, the arm.

[0014]

1 is a partial cross-sectional plan view showing an essential part of a magnetic circuit in an embodiment of the present invention, FIG. 3 is a perspective view showing a locked state in an embodiment of the present invention, and the same parts are shown in FIG.
The same reference numerals are used. In FIGS. 1 and 3, the permanent magnet 3 is formed on a flat plate in a substantially fan shape by using, for example, an Nd-Fe-B based magnet material, and is magnetized in the thickness direction so that N and S magnetic poles appear on the surface. Constitute. When manufacturing such a permanent magnet 3, two separately prepared permanent magnets may be joined together by a broken line portion to be integrated.

A tip 8 made of a ferromagnetic material such as soft iron is integrally provided on the end surface of the permanent magnet on the side where the locking operation is performed.

Next, when assembling the magnetic circuit, as shown in FIG.
The pillar 2 as shown in FIG. 4 may be fixed to the yoke 1 to which the permanent magnet 3 is fixed as described above, another yoke 1 may be interposed, and the fixing may be performed by a set screw (not shown).

Next, FIG. 2 is a plan view showing the arm 5 in the embodiment of the present invention, and the same portions are designated by the same reference numerals as those in FIG. In FIG. 2, 7a is a hole through which the shaft 7 in FIG. 4 is inserted. Reference numeral 9 denotes a locking piece made of a ferromagnetic material, which is provided at one side end portion of the movable coil 6 and in FIG.
It is provided on the end face of the permanent magnet shown in FIG. The locking piece 9 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, polyphenylene sulfide resin containing glass fiber, and can be integrally molded with the movable coil 6 and the locking piece 9 by injection molding means.

A rocking type actuator can be constructed by assembling the magnetic circuit and the arm having the above construction as shown in FIG. The result of evaluating the locking characteristic of the arm 5 with respect to this swing type actuator will be described.

FIG. 5 is a diagram showing the relationship between the arm angle and the torque in the embodiment of the present invention. In FIG. 5, the position where the arm angle is 0 ° shows the case where the movable coil 6 of the arm 5 shown in FIG. 2 is located at the S pole side end of the permanent magnet 3 shown in FIG. At this position, the locking piece 9 shown in FIG. 2 faces the ferromagnetic chip 8 shown in FIG.
Therefore, the locking piece 9 is in the vicinity of the magnetic field of the ferromagnetic chip 8 and is attracted to the ferromagnetic chip 8, so that the arm 5 is locked.

In FIG. 5, the torque means the torque required to swing the arm 5 in the horizontal direction when the arm 5 shown in FIG. 2 is at the position of the arm angle shown on the horizontal axis. In the present embodiment, the torque at the arm angle of 0 ° is a little over 20 g · cm, which is sufficiently higher than the 15 g · cm required for locking the arm 5, so the arm 5 is
Can be fully locked. Then, the arm 5 swings and the arm angle 3.6, which is the boundary between the latch zone and the data zone.
In the data zone when the rocking exceeds 50 °, the torque value is significantly reduced to less than 1 g · cm. Therefore, the arm 5 can be swung smoothly, and the lock characteristic can be remarkably improved as compared with the case where the ferromagnetic chip (locking piece) is not installed.

In the present invention, the size of the ferromagnetic chip (locking piece) installed at the end face of the permanent magnet on the side where the lock operation is performed and the portion of the movable coil corresponding to the end face is the same as that of the applicable swing actuator. It can be appropriately selected according to the shape and magnetic characteristics of the constituent permanent magnets 3. For example, the height dimension of the ferromagnetic chip installed on the end face of the permanent magnet on the locking side is about the same as the height dimension of the permanent magnet,
The width and thickness are preferably set to 1 to 10 mm and 0.1 to 1 mm depending on the required locking force. Further, the size of the locking piece installed at the portion of the movable coil corresponding to the end face of the permanent magnet is, for example, the height dimension is almost the same as the coil thickness dimension, and the width and the thickness dimension are almost the same as those of the ferromagnetic chip provided in the permanent magnet. It is preferable to set the same size.

In the present invention, the yokes 1 and 1 are connected to the support columns 2.
Although an example in which a set screw is used as a means for fixing via a screw has been described, for example, a screw on a rivet may be driven in or press-fitted for fastening.

[0023]

Since the present invention has the structure and operation as described above, the ferromagnetic chip provided on the end face on the side where the permanent magnet is locked and the end face when the oscillating actuator is not operated. It is possible to reliably lock the movable coil, that is, the arm, by the magnetic attraction force acting between the movable coil and the locking piece provided at the position of the movable coil.
Further, when the movable coil is operated, the ferromagnetic attraction piece of the arm is located away from the ferromagnetic chip on the end face of the permanent magnet, so that the magnetic attraction force does not act, and the movable coil, that is, the arm swings. There is an effect that the arm can be swung smoothly without affecting the movement at all.

[Brief description of drawings]

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 plan view showing an arm according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a locked state in the embodiment of the present invention.

4A and 4B are explanatory views of a main part showing an example of a conventional rocking type actuator, in which FIG. 4A is a partially crushed plane, and FIG. 4B is a view in the direction A in FIG.

FIG. 5 is a diagram showing a relationship between an arm angle and torque in the example of the present invention.

[Explanation of symbols]

 2 Support 3 Permanent magnet 8 Ferromagnetic chip 9 Ferromagnetic locking piece

Claims (1)

[Claims] 1. A housing in which a permanent magnet is fixed to one of a pair of yokes provided 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. A movable coil that is movable along the surface of the permanent magnet in the magnetic gap and that locks the arm when it is inactive. Type actuator, the permanent magnets are magnetized in the thickness direction, and the length of the permanent magnets in the direction perpendicular to the arc locus of the movable coil increases from the central portion to the outer end portion of the movable coil operating range. In addition, a tip made of a ferromagnetic material is provided on the end surface of the outer end of the permanent magnet on the side where the locking operation is performed, and the movable coil portion corresponding to the end surface is made of a ferromagnetic material. Rocking type actuator, characterized in that a locking piece.