JPS63206146A - Actuator - Google Patents

Abstract

PURPOSE:To maintain the thrust of an actuator constant by so forming permanent magnets as to sequentially increase the magnetization intensity distribution of the magnets disposed along the advancing direction of a movable armature. CONSTITUTION:A movable armature 1 is formed of a laminate of soft magnetic materials, such as soft irons, and wound with a coil 2. It moves along a dipole permanent magnet 3. The magnet 3 is so magnetized as to show gradual increases in magnetization intensity distribution from the boundary of N- and S-poles toward both ends of the movable range of the armature 1. Thus, an actuator which does not generate a thrust ripple is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an actuator, particularly a seek mechanism ring for a recording/reproducing head of a magneto-optical recording device, a hard disk drive device, etc., and an actuator for high-speed precision movement.

[Conventional technology]

FIG. 10 shows a voice coil type (hereinafter referred to as VCM) actuator according to a conventional example. In this VCM, the magnetic flux generated by the permanent magnet 11 enters the magnetic yoke 12, and the movable air-core coil 13 wound around the magnetic yoke 12 runs along the magnetic yoke 12 so as to cross the magnetic flux. Moving.

[Problem that the invention seeks to solve]

However, in the VCM, since the moving coil 13 exists between the permanent magnet 11 and the magnetic yoke 12, the gap between the magnetic poles is large, and therefore the operating point of the permanent magnet 11 has to be low. Ta. In other words, the magnetic flux density generated by the permanent magnet 11 is small compared to the energy product of the permanent magnet 11, and the actuator is forced to have low efficiency.In order to obtain the desired thrust, a large current must be passed through the coil 13. has been taken. However, such a method has the problem that Joule heat causes a difference in thermal expansion between various parts within the recording device, sometimes making it difficult to read written information.

The present invention has been made in view of the above points, and an object of the present invention is to provide an energy-saving actuator that has a simple configuration and enables smooth driving.

(Means for Solving the Problems) The actuator according to the present invention includes a movable armature in which a coil is wound around a soft magnetic material, and two permanent poles arranged on one or both sides of the movable armature along the direction of movement of the movable armature. It consists of a magnet and a magnetic yoke arranged to surround a movable armature and a permanent magnet, and furthermore, the magnetization intensity distribution of the permanent magnet is sequentially directed from the boundary between the N pole and the S pole to both ends of the movable range of the movable armature. It is formed to become larger.

(Function) In this invention, the movable armature moves in a predetermined direction by energizing the coil of the movable armature.

(Embodiment) FIG. 1 is a perspective view showing an embodiment of an actuator according to the present invention.

In Fig. 1, the guide in the direction of movement is omitted, but
A movable armature 1 is made of a laminated body of a soft magnetic material such as soft iron, has a coil 2 wound around it, and is adapted to move along a two-pole permanent magnet 3. 4 is a magnetic yoke.

In this way, since the movable armature 1 is used as the mover, the air gap between the permanent magnet 3 and the movable armature 1 can be made very small, for example, 0.5 mm or less, and the operating point of the permanent magnet 3 is high and the magnetic flux density is large. can be obtained, and a high-output actuator can be constructed.

However, if the permanent magnet 3 is uniformly and completely magnetized with this configuration, thrust ripples will occur due to reluctance force. In this case, the N-pole boundary is the movable armature 1
The movable armature 1 is most stable when the centers of the two face each other.

FIG. 2 shows the thrust force when a current is passed through the coil 2 and the reluctance force in a non-energized state with respect to each position of the movable armature 1. The origin is defined as the point where the center of the movable armature 1 coincides with the boundary between the N and 5 poles of the permanent magnet 3. As is clear from Figure 2, the thrust depends on the position of the armature and is not constant.

In this invention, as a result of various studies to reduce the reluctance scale to a negligible level and to keep the thrust at each position constant, the magnetization intensity distribution of the permanent magnet 3 is changed from the boundary between the N8i and the S pole as described above. By applying magnetization to the movable armature in such a manner that the magnetization becomes larger toward both ends of the movable range, an actuator that does not generate thrust ripples was obtained.

The magnetization intensity distribution of the permanent magnet 3 according to the present invention is
It looks like the picture. Further, FIG. 4 shows the thrust force when a current is passed through the coil 2 and the reluctance force in a non-energized state. As is clear from FIG. 4, almost no reluctance force is generated, and the thrust force is approximately constant except at the ends.

FIG. 5 shows an actuator in which permanent magnets 3A and 3B are also arranged at both ends inside the magnetic yoke 4. By doing so, it is possible to prevent the thrust force from decreasing at both ends, and it is possible to take a long stroke. Note that the permanent magnets 3A and 3B placed at both ends may have a constant thickness and magnetization distribution.

FIG. 6 is a characteristic diagram of the actuator shown in FIG. 5, and compared to the characteristic diagram of FIG. 4, it can be seen that the thrust force is constant up to the end.

FIG. 7 shows a case where permanent magnets 3,3' are arranged on both sides of the movable armature 1, and by doing so, an actuator with even higher output can be constructed.

Fig. 8 shows an actuator that drives the movable armature 1 so that the movement describes an arc, but the construction principle is exactly the same as the linear drive type of the embodiments shown in Figs. 1, 5, and 7 above. .

FIG. 9 shows an example of a magnetizer for uniformly magnetizing the permanent Ti1 stones 3, 3', etc., which are the constituent elements of this invention. By inserting the permanent magnet 3 to be magnetized between them, the gap between the yoke 5 and the back yoke 7 is large near the N-pole-8-pole boundary and small at both ends. coil 6A
, 6B in opposite directions to each other, the permanent magnet material 3° is magnetized with a desired strength and becomes a permanent magnet 3.

C Effects of the Invention] As explained in detail above, the present invention includes a movable armature in which a coil is wound around a soft magnetic material, and a two-pole permanent magnet arranged on one or both sides of the movable armature along the direction of movement of the movable armature. and a magnetic yoke disposed to surround a movable armature and a permanent magnet, and furthermore, the magnetization intensity distribution of the permanent magnet gradually increases from the boundary between the north pole and the south pole toward both ends of the movable range of the movable armature. This has the advantage that the operating point of the permanent magnet is high, an energy-saving actuator, and a constant thrust force can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between armchair position and thrust when the permanent magnet is uniformly magnetized, and FIG. 3 is a diagram showing the relationship between the armchair position and thrust when the permanent magnet is magnetized uniformly. FIG. 4 is a diagram showing the strength distribution of the magnet, FIG. 4 is a diagram showing the relationship between armchair position and thrust in the present invention, FIG. 5 is a perspective view showing another embodiment of the present invention, and FIG. Figures 7 and 8 are perspective views showing still other embodiments of each invention, and Figure 9 shows how the permanent magnet of this invention is magnetized to a desired level. FIG. 10 is a perspective view showing an example of a conventional actuator. In the figure, 1 is a movable armature, 2 is a coil, 3 is a permanent magnet, and 4 is a magnetic yoke. Fig. 1 Fig. 2 - Armature 7 position (relative value) Fig. 3 Fig. 4 Fig. 7-Matineer position (att 0) Fig. 5 Fig. 6 - Armature position (relative value) Fig. 7 Fig. 8 Fig. 9 Figure 10

Claims (3)

[Claims] (1) A movable armature with a coil wound around a soft magnetic material, a two-pole permanent magnet placed on one side or both sides along the direction of movement of the movable armature, and a magnet that surrounds the movable armature and the permanent magnet. and a magnetic yoke disposed therein, and further characterized in that the magnetization strength distribution of the permanent magnet is formed such that it gradually increases from the boundary between the north pole and the south pole toward both ends of the movable range of the movable armature. actuator. (2) The actuator according to claim (1), wherein the movable armature moves linearly. (3) The actuator according to claim (1), wherein the movable armature moves in an arc shape.