JPH0695387B2 - Voice coil type actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil type actuator for adjusting the position of a driven body such as a light receiving element portion of a photodetector in an optical disc reproducing apparatus.

[Conventional technology]

FIG. 6 is a block diagram showing a conventional voice coil type actuator. In the figure, 1 is a driven body whose position is adjusted in a small range in the axial direction, and 2 is a cylindrical support that fixes the driven body 1 and moves in the axial direction and is made of a non-magnetic material. Reference numeral 3 denotes a cylindrical axial driving coil wound around the outer periphery of the support 2, 4 denotes a cylindrical yoke made of a magnetic material, and a corresponding annular projection 4a is formed on the coil via an air gear tap. The bottom plate 5 made of a magnetic material is fixed to form a magnetic path. A pair of upper and lower elastic supporting members 6 are fixed to the upper and lower inner circumferences of the yoke 4 and elastically support the cylindrical supporting member 2 so as to be capable of small axial movement, and are composed of a spring member, a rubber body and the like. Reference numeral 7 denotes a permanent magnet fixed on the bottom plate 5 at an axial center position, and 8 fixed on the permanent magnet 7, on the inner circumference of the support body 2 via an air gear cup, and at a height position corresponding to the cylindrical coil 3. It is a columnar massive yoke.

In the above-mentioned conventional actuator, the magnetic flux Φ generated by the permanent magnet 7 enters the annular projection 4a from the massive yoke 8 orthogonally to the coil 3 in the radial direction as shown by the dotted line.
4, It can be returned to the permanent magnet 7 through the bottom plate 5.

When a current is passed through the coil 3, an orthogonal magnetic flux Φ produces a force in the axial direction to move the driven body 1 in the axial direction via the support 2. By changing the magnitude and direction of the current,
The axial position of the driven body 1 can be adjusted and controlled.

[Problems to be solved by the invention]

In the conventional voice coil type actuator as described above, the magnetic flux Φ generated from the permanent magnet 7 requires a long magnetic path passing through the yoke 4 and the bottom plate 5, resulting in a large magnetic resistance and a low efficiency and a large external shape. There was a problem that became.

The present invention has been made to solve such problems, and shortens the path of magnetic flux generated from a permanent magnet,
The objective is to improve the magnetic flux efficiency of the permanent magnet and to obtain a voice coil type actuator whose outer shape is miniaturized.

[Means for solving problems]

A voice coil actuator according to a first aspect of the present invention comprises a cylindrical support body made of a non-magnetic material, and a driven body being fixedly supported on an upper end portion thereof, and a cylindrical support body formed by winding in a square shape. 4 or more axial drive coils which are arranged in the circumferential direction and are adjacent to each other in the circumferential direction in order so that the current directions thereof are opposite to each other, and the above-mentioned cylindrical support body is provided with an air gap inside or outside thereof. A plurality of permanent magnets, which are arranged in the first yoke so as to be divided in the circumferential direction at positions corresponding to the upper side and the lower side of the axial drive coils, respectively, and which are adjacent to each other and have mutually different polarities, and the axial drive Between a second yoke installed inside or outside of the cylindrical support having the coil for air, corresponding to the permanent magnet via an air gap, and between the cylindrical support and the yoke outside thereof. Interposed, axially supporting the cylindrical support Those having a pair of upper and lower elastic supporting members can be elastically support the movement of.

A voice coil type actuator according to a second aspect of the present invention is made of a non-magnetic material, and has a cylindrical support body that fixedly supports a driven body below an upper end portion thereof, and is formed in a square shape. Four or more axial drive coils, which are circumferentially adjacent to the outer circumference of the cylindrical support and are arranged in order so that the current directions thereof are opposite to each other, and inside or outside the cylindrical support. A plurality of permanent magnets, which are arranged in the first yoke in the circumferential direction in a divided manner in the circumferential direction at positions corresponding to the upper side and the lower side of the respective axial drive coils via air gaps, and which are adjacent to each other and have different polarities; A second yoke installed inside or outside of the cylindrical support on which the axial drive coil is mounted so as to correspond to the permanent magnet via an air gap, and the cylindrical support and the outer joint thereof. A cylinder that is interposed between iron and A pair of upper and lower elastic support members elastically supporting the support body so as to be movable in the axial direction is provided, and the upper elastic support member of the pair of elastic support members is arranged at a position higher than the driven body. It is a thing.

[Action]

In the first aspect of the present invention, the magnetic flux generated from one of the permanent magnets adjacent to each other in the axial direction is orthogonal to one side of the corresponding coil in the circumferential direction and passes through the corresponding second yoke to form the same coil. Enters the other permanent magnet that is orthogonal to the other side in the circumferential direction and is adjacent in the axial direction, and returns to the one permanent magnet through the first yoke on the back. When each coil is energized, a force in the axial direction is generated by the magnetic flux and the coil current orthogonal to the upper and lower sides, and the driven body is moved in the axial direction via the support body. The magnetic path is a short path that passes between permanent magnets of opposite polarities that form a pair in the axial direction.

In addition, the cylindrical support body in which four or more quadrangular coils are arranged on the outer periphery has eight or more line symmetry axes in an axially orthogonal cross section, and with respect to an axially orthogonal direction external force in an arbitrary direction, Prevents changes in posture due to tilting by balancing the coil layout.

Further, in the second invention of the present invention, the upper elastic supporting member of the pair of elastic supporting members is arranged at a position higher than the driven body, and therefore, in comparison with the first invention, It is possible to stabilize the support of the driving body.

〔Example〕

1 and 2 are a structural view and an exploded perspective view showing an embodiment of a voice coil type actuator according to the present invention, in which 1, 2, 5 and 6 are the same as those of the conventional device. Reference numeral 11 denotes an axial drive coil which is wound in a square shape and is arranged and fixed on the outer circumference of the cylindrical support 2 in order in the circumferential direction, and has an upper side 11a and a lower side 11b in the circumferential direction. The directions of current flow between adjacent ones are opposite. 12 is a position corresponding to the upper side 11a and the lower side 11b of each coil 2,
It is arranged on the inner circumference of the support body 2 via an air gear cup, and
A plurality of permanent magnets, which are arranged in a pair below and divided in the circumferential direction, are adjacent to each other and have different polarities. 13 is a mounting body fixed to the bottom plate 5 about the axis, and 14 is this mounting body.
It is a ring-shaped first yoke fixed on 13 and each permanent magnet 12 is fixed from the back. In addition, this first yoke 14 is a mounting body
It may be formed integrally with 13. Reference numeral 15 is a cylindrical second yoke fixed to the bottom plate 5, and protrusions 15a are provided on the outer periphery of the support body 2 at positions corresponding to the upper and lower pairs of permanent magnets 12 via air gears.

Fig. 3 shows each permanent magnet 12 and each protrusion for each coil 11.
The layout of 15a is shown in an exploded view.

In the actuator of the above-described embodiment, the magnetic flux φ generated from the N pole of one of the upper and lower paired magnets 12a of the permanent magnets 12 is the upper side 11a of the coil 11 as shown by the dotted line.
To the protrusion 15a of the yoke 15 at right angles to the radial direction, and the lower side 11b of the coil 11 to the S direction of the other magnet 12b at right angles to the radial direction.
It can enter the pole and return to the south pole of one magnet 12a via the yoke 14 at the back.

As described above, most of the magnetic flux emitted from the permanent magnet 12 passes through the shortest magnetic path, and the magnetic flux is effectively utilized.

When a current is passed through the coil 11, an axial force is generated by the orthogonal magnetic flux Φ, and the driven body 1 is moved via the support body 2 in the axial direction. By changing the magnitude and direction of the current of the coil 11, the axial position of the driven body 1 can be controlled.

Further, the cylindrical support body 2 in which four quadrangular coils 11 are arranged on the outer periphery has eight line symmetry axes in a cross section orthogonal to the axis,
The balance prevents the posture change with respect to the inclination with respect to the external force in the direction orthogonal to the axis in an arbitrary direction. That is, when an impact force or the like is applied in the direction orthogonal to the axis and in the direction orthogonal to the axis of line symmetry, the arrangement balance of the coil 11 prevents the inclination change of the cylindrical support 2 and prevents the optical axis and the medium (disk). Maintain a right angle with. In the above embodiment, four coils are arranged, but by increasing the number of coils, the inclination change of the cylindrical support 2 is prevented against an external force in the axis orthogonal direction of an arbitrary direction. Needless to say.

FIG. 4 is a block diagram of an actuator showing another embodiment of the present invention. The upper and lower sides 11a and 11b of the coil 11 are fixed to the respective protrusions 25a of the first yoke 25 by means of a pair of upper and lower permanent magnets 17 via air gears. Reference numeral 18 denotes a mounting body fixed to the central portion of the shaft on the bottom plate 5, 19 denotes a second yoke fixed to the mounting body 18, and is formed on the inner circumference of the support body 2 via an air gear trap and vertically. It is located at a height corresponding to the permanent magnet 17 of. On the outer periphery of this yoke 19,
An axial notch groove 19a is provided at a position corresponding to an adjacent portion of each permanent magnet 17 with respect to the circumferential direction, so that the magnetic flux by the permanent magnet 17 is effectively orthogonal to the upper side 11a and the lower side 11b of the coil 11. . The yoke 19 may be formed integrally with the mounting body 18.

FIG. 5 is a block diagram of an actuator showing another different embodiment of the present invention. The driven body 1 is fixed to the upper side of the cylindrical support 20, and the yoke 15 is provided with a notch hole 15b that allows the driven body 1 to move in the axial direction. The upper elastic support 6 is located above the driven body 1 and has a yoke 15
And the cylindrical support 20 to improve the stability of the support of the driven body 1.

Alternatively, each coil 11 may be formed by continuous winding, and the winding directions of the adjacent coils may be reversed so that the current directions are opposite to each other.

Further, although the coil 11 is formed by winding the coil conductive wire in the above embodiment, it may be formed by printed wiring and fixed to the cylindrical support 2.

Further, the cylindrical support 2 may be made of an insulating material such as a synthetic resin material, and the printed wiring may be directly provided on the outer periphery thereof to form each coil 11.

In addition, the opening side of the yoke 15 is covered with a magnetic material to magnetically shield the opening side of the driven body 1 except for the minimum necessary range such as the outlet, so that the leakage flux of the permanent magnet is prevented from affecting the outside. Good. In this case, if the bottom plate 5 is made of a non-magnetic material, this outer circumference is also covered with the magnetic material.

Further, although the yokes 15 and 25 are made of a magnetic material, if the magnetic flux still leaks to the outside, the yoke portion may be covered with the magnetic material.

〔The invention's effect〕

As described above, according to the first aspect of the present invention, four or more coils wound in a square shape are sequentially arranged on the outer periphery of the cylindrical support in the circumferential direction, and Currents are made to flow in mutually opposite directions, and permanent magnets are arranged at positions corresponding to the upper side and the lower side of each coil above and below the inner circumference side or the outer circumference side of the support body through an air gear trap. Are adjacent to each other and have opposite polarities, each permanent magnet is fixed by a first yoke at the back portion, and further, a permanent magnet group corresponding to the permanent magnet group is provided on the opposite side of the support from the permanent magnet via an air gear gap. Since the two yokes are provided, the magnetic path of the magnetic flux of the permanent magnet is shortened, the magnetic flux is efficiently used, and the outer shape can be made smaller.

Further, by disposing four or more quadrangular coils on the outer circumference of the cylindrical support, there are eight or more line-symmetric axes in the cross section orthogonal to the axis, and with respect to an external force in the axis orthogonal direction in any direction. , It is possible to prevent the change in posture with respect to the inclination in balance. That is, even when an impact force or the like is applied in a direction orthogonal to the axis and from an arbitrary direction, it is possible to prevent the inclination change of the cylindrical support body by the coil arrangement balance and maintain the right angle between the optical axis and the medium (disk). Therefore, stable reproduction can be performed without causing a change in signal.

Further, according to the second invention of the present invention, since the elastic supporting member is arranged above the driven body, it is possible to further stably support the driven body as compared with the first invention. Can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a voice coil type actuator according to the present invention, FIG. 2 is an exploded perspective view of magnetic circuit components shown in FIG. 1, and FIG. 3 is a coil and permanent magnet shown in FIG. FIG. 4 is a development view showing the arrangement, FIGS. 4 and 5 are configuration diagrams showing other different embodiments of the present invention, and FIG. 6 is a configuration diagram of a conventional actuator. 1 ... Driven body, 2 ... Cylindrical support, 6 ... Elastic support member, 11 ... Axial drive coil, 11a ... Upper side, 11b ...
… Lower side, 12,17 …… Permanent magnet, 14,25 …… First yoke, 1
5,19 …… Secondary yoke, 20 …… Cylindrical support. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (8)

[Claims] 1. A cylindrical support body which is made of a non-magnetic material and has a driven body fixedly supported on its upper end portion, and a cylindrical winding body which is formed in a square shape and is circumferentially adjacent to the outer circumference of the cylindrical support body. Four or more axial drive coils arranged in order so that the current directions are opposite to each other, and an upper side and a lower side of each of the axial drive coils with air gaps inside or outside the cylindrical support. A plurality of permanent magnets, which are arranged in the first yoke at corresponding positions in the circumferential direction in a divided manner and are adjacent to each other and have mutually different polarities; and a cylindrical support having the axial drive coil mounted thereon. A second yoke installed inside or outside via an air gap corresponding to the permanent magnet, and interposed between the cylindrical support and the outside yoke.
A voice coil type actuator comprising a pair of upper and lower elastic support members that elastically support a cylindrical support so as to be movable in the axial direction. 2. A voice coil type actuator according to claim 1, wherein a plurality of drive coils are continuously wound. 3. A voice coil type actuator according to claim 1, wherein a plurality of drive coils are formed by printed wiring. 4. A magnetic material covers the outside of the non-magnetic part of the outermost peripheral part of the cylindrical support except the part of the opening of the yoke that does not require removal of the driven part. The voice coil type actuator according to any one of claims 1 to 3, which is magnetically shielded. 5. A cylindrical support body which is made of a non-magnetic material and fixedly supports a driven body below an upper end portion thereof, and a cylindrical support body which is wound in a square shape and is circumferentially formed on an outer periphery of the cylindrical support body. Moreover, four or more axial drive coils arranged in order so that the current directions thereof are opposite to each other are adjacent to each other, and the upper side of each axial drive coil is provided inside or outside the cylindrical support body with an air gap. And a plurality of permanent magnets arranged in the first yoke at positions corresponding to the lower side in the circumferential direction in a divided manner and adjacent to each other and having different polarities, and a cylindrical shape having the axial drive coil mounted thereon. A second yoke installed inside or outside the support body via an air gap corresponding to the permanent magnet, and a cylindrical support body provided between the cylindrical support body and the outer yoke. An upper and lower pair that elastically support the axial movement The above-mentioned elastic supporting member, wherein the upper elastic supporting member of the pair of elastic supporting members is disposed above the driven body. 6. A voice coil actuator according to claim 5, wherein a plurality of drive coils are continuously wound. 7. The voice coil type actuator according to claim 5, wherein a plurality of drive coils are formed by printed wiring. 8. A magnetic material covers the portion of the opening of the yoke on the outer peripheral side of the cylindrical support, excluding the portion required to take out the driven body, and the outside of the non-magnetic portion of the outermost peripheral components. The voice coil type actuator according to any one of claims 5 to 7, which is magnetically shielded.