JPS63187425A - Voice coil type actuator - Google Patents

Abstract

PURPOSE:To miniaturize the actuator while improving the efficiency of the magnetic field by arranging plural drive coils to a position corresponding to each pole of the magnet and winding a coil corresponding to N and S poles of the magnet in reverse direction relatively so as to decrease the length of the path of the magnetic flux induced from the magnet. CONSTITUTION:The magnet constituted by polarizing and magnetizing symmetrically plural number of anisotropic magnets 11a, 11b having a radial orientation direction in the axial direction is provided, plural drive coils 12a, 12b wound corresponding to the magnet is provided to a cylindrical holder 1 fitted with a object 2 to be drive and yokes 13, 14 are provided to the inside and outside of them. The drive coils 12a, 12b are wound in opposite directions and the direction of the magnetic flux 15 penetrated therethrough is opposite to each other. Thus, the path for ineffective magnetic flux is almost eliminated to decrease the length of the path for the magnetic flux, the efficiency of the magnetic field is improved and the voice coil type actuator which is to be miniaturized is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a voice coil actuator, and particularly to a voice coil actuator used for optimal position control of a photodetector, etc. in an optical disc playback device. be.

[Conventional technology]

FIG. 4 is a sectional view showing an example of a conventional voice coil type actuator.

In the figure, reference numeral (1) indicates a cylindrical holder, for example, a cylindrical holder, for driving a driven object (2) in the axial direction, and the yoke (1) is supported by a plurality of spring members (3) provided in the radial direction. 4) is supported.

(5) is a drive coil wound multiple times around the outer peripheral surface of the cylindrical holder (1), and is wound at a position facing the protrusion (4a) of the yoke (4). (6) is a magnet fixed on the axis of the cylindrical holder (1) and oriented in the axial direction, and a yoke (7) is located at the tip of the magnet (6) facing the drive coil (5). It is arranged.

Since the conventional device is configured as described above, the magnetic flux (8) generated in the axial direction from the magnet (6) is redirected in the radial direction by the yoke (7), and the driving coil A/(5) It has a path that passes through perpendicularly/crosswise to the winding direction and returns to the magnet (6) from the protrusion (4a) of the yoke (4).

Therefore, when current is passed through the drive coil (5), the orthogonal magnetic flux (
From the relationship with 8), according to 7 Lemming's left hand rule,
Cylindrical holder (1) around which the drive coil (5) is wound
receives a force in the axial direction and thus drives the driven object (2).

Therefore, the position of the driven object (2) is controlled by changing the magnitude and direction of the current flowing through the drive coil (5).

[Problem that the invention seeks to solve]

In order for the conventional voice coil type actuator to be configured and act as described above, the magnetic flux emitted from the magnet (6) requires a long path, which results in poor efficiency and makes it difficult to downsize the actuator. There was this problem.

This invention was made to solve the above-mentioned problems, and provides a voice coil type actuator that can shorten the path of magnetic flux emitted from a magnet to increase the efficiency of the magnetic field and downsize the actuator. The purpose is to

[Means for solving problems]

The voice coil actuator according to the present invention includes an anisotropic magnet formed in a cylindrical shape and oriented in the radial direction. ! A magnet configured by polarizing and magnetizing T several poles symmetrically, a driven object held in a cylindrical holder, and a plurality of drive coils wound multiple times around the cylindrical holder; It has a plurality of yokes and a plurality of spring members that support the cylindrical holder and allow the cylindrical holder to move only in the axial direction relative to the magnet, and the magnet, A cylindrical holder, a drive coil, and a yoke are arranged concentrically so that the cylindrical holder and the drive coil are sandwiched between the magnet and the yoke, and the plurality of drive coils are arranged at parts corresponding to each type of magnet. The coils provided therein and corresponding to the north and south poles of the magnet are wound in relatively opposite directions.

[Effect]

Since the voice coil actuator l according to the present invention is configured as described above, there are almost no invalid paths for magnetic flux, the total path is shortened, and the efficiency of the magnetic field is improved.

〔Example〕

The present invention will be explained below based on the drawings showing one embodiment thereof.

In the drawings, the same reference numerals as those in the conventional device indicate the same or equivalent components as in the conventional device.

Figure 1 and Figure 2, which is a detailed enlarged view of the vicinity of the coil.
In the figure, symbols (xxa) and (11b) are composed of anisotropic magnets oriented in the radial direction, respectively, with N pole and
Magnets with S-polarity, (12a) and (12b) correspond to magnets (tla) and (1tb), respectively,
The drive coil (13) is a yoke that is wound in the opposite direction around the cylindrical holder (1), and its protrusion (ia
A) is provided corresponding to the driving coil # (tza) (tzb). Moreover, the code|symbol (14) is a yoke.

Since this embodiment is configured in this way, the magnetic flux (15) emitted from the N pole of the magnet (ila) passes through the drive coil /I/ (12a) and is transferred to the yoke (13).
The drive coil (12b) is reversed at the protrusion (13a).
passes through and returns to the south pole of the magnet (llb).

Since the winding directions of the drive coils (12a) and (12b) are opposite to each other, and the directions through which the magnetic flux (15) passes are opposite, Fleming's left-hand rule dictates that the drive coils (12a) and (12b) are wound in the same direction. experiences a force and therefore moves in the direction of arrow (16). Therefore, the drive coil (lz
a) By changing the magnitude and direction of the current flowing through (z2b), the position of the driven object (2) can be controlled.

In addition, in the above embodiment, magnets) (txa) (ub
) was placed inside the cylindrical holder (1), and the yoke (13), that is, the protrusion (X3a) was placed outside the drive coil.
1a) (t 1b) to the drive coil (12a) (12b
), and the yoke (13) is placed on the outside of the cylindrical holder (1
) may be placed inside.

Further, this voice coil type actuator l may be shielded with a magnetic material except for necessary parts such as an outlet for a driven object.

〔Effect of the invention〕

As described above, according to the present invention, a magnet is provided in which a plurality of anisotropic magnets having an orientation direction in the radial direction are symmetrically polarized and magnetized in the axial direction, and the magnet is wound in a manner corresponding to the magnet. A plurality of drive coils are mounted on a cylindrical holder to which the driven object is attached, and yokes are provided on the inside and outside of the coils, so it is possible to almost eliminate the gauze path of ineffective magnetic flux, and to reduce the path of differential magnetic flux. This has the effect of providing a voice coil type actuator l that can shorten the length of the magnetic field, thereby increasing the efficiency of the magnetic field and, as a result, making it possible to downsize the device.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a voice coil type actuator I according to an embodiment of the present invention, FIG. M2 is a detailed enlarged view of the vicinity of the coil in FIG. 1, and FIG. 3 is a longitudinal section showing another embodiment of the invention The plan view and FIG. 4 are longitudinal sectional views of a conventional voice coil type actuator I. In the figure (1)... cylindrical holder (cylindrical holder),
(2)...Driven object, (3)...Spring member, (11a)
(11b)...Magnet, (12a)(12b)...
Drive coil, (13), (14)...Yoke. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 1 Figure 2 I-16

Claims (3)

[Claims] (1) A magnet composed of a plurality of anisotropic magnets formed in a cylindrical shape and oriented in the radial direction and polarized and magnetized symmetrically in the axial direction, and a magnet held in a cylindrical holder. A driving object, a plurality of drive coils wound around the cylindrical holder a plurality of times, a plurality of yokes, and a plurality of yokes that support the cylindrical holder and move the cylindrical holder in the axial direction of the magnet. The magnet, the cylindrical holder, the drive coil and the yoke are arranged concentrically so that the magnet and yoke sandwich the cylindrical holder and the drive coil. The plurality of drive coils are arranged at portions corresponding to each pole of the magnet, and the coils corresponding to the north and south poles of the magnet are wound in relatively opposite directions. A voice coil actuator characterized by: (2) The voice coil type actuator according to claim 1, wherein the plurality of spring members have one ends attached to the cylindrical holder at a plurality of radial and axial positions, respectively. (3) The voice coil type actuator according to claim 1 or 2, wherein the voice coil type actuator is shielded with a magnetic material except for the minimum necessary opening including the outlet for taking out the driven object. .