JPS61273163A - Voice coil motor - Google Patents

Abstract

PURPOSE:To uniformly generate a torque by deciding the magnetization of a permanent magnet so that the magnetic flux density of an air gap between an outer permanent magnet and a main core and the magnetic flux density of an air gap between an inner permanent magnet and the main core are uni formly distributed. CONSTITUTION:A coil 3 is rockably supported at a shaft 2 as a center, and a main core 5a is arranged to pass the coil 3. an outer permanent magnet 18 is disposed at the outside of the maximum circle drawn by the profile of the coil 3 upon rocking of the coil 3 to generate an outer magnetic flux which passes a main core 5a through the coil 3. An inner permanent magnet 19 is disposed at the inside of the minimum circle drawn by the profile of the coil 3 upon rocking of the coil 3 to generate an inner magnetic flux which passes the core 5a through the coil 3. The magnets 18 and 19 are magnetized radially to have a center at the opposite side to the side of the coil 3 with respect to the magnets 18, 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a rotary and oscillating voice coil motor in which a coil is arranged to be able to oscillate about a single axis.

In particular, the torque on the -axis generated by the coil Cζ is uniformly applied over the entire swing range of the coil σ).
This relates to a configuration that can be easily realized.

[Prior art and its problems]

The above-mentioned rotary oscillating voice coil motor is conventionally constructed as shown in FIG. 3IC. In other words, Fig. 3 (6) is a side view, and Fig. 3 (■) is a Z-Z in the same figure (6).
In the cross-sectional views, % 1.1 in both figures is two arms with one end of each fixed to the shaft 2I that drives the load, and both arms 1 and 1 are arranged in advance to be parallel. There is. Reference numeral 3 denotes a coil having an air core 4 having a rectangular cross section, and the coil 3 is held between the free ends t of both arms 1.1. 5 is a three-piece iron core formed into a fan shape.

The iron core 5 includes a main iron core 5a forming the central part of the tripod σ), an outer iron core 5b forming the fan-shaped outer leg of the tripod, and an inner fan-shaped inner leg of the tripod σ). The shape 1
1i3 L, inner core 5C, core 5a and core 5
joint parts 5d, 5d magnetically connecting the iron core 5a and
The tripod core 5 and the coil 3 are arranged in such a way that the main core 5a passes through the air core 4. 6 is the main iron core 5a and the joint portion 5d.

5d and an arc-shaped outer gap surrounded by the outer core 5b, and 7 is an arc-shaped inner gap surrounded by the main core 5a, joint parts 5e, 5e, and the inner core 5C.

The main iron core 5a and the gaps 6 and 7 are such that the coil 3 supported by the arm 1.1 can swing around the shaft 2 within the gaps 6 and 7, with the iron core 5a passing through the air core 4. It is configured as n. 8 is an arc-shaped outer core 5b which is bonded to the outer core 5b so as to face the coil 3Iζ in the air gap 6.
The outer permanent magnet 9 is an arc-shaped inner permanent magnet bonded to the inner core 5C in the air gap 7 so as to face the coil 3, and the outer permanent magnet 8 is connected to the main core 5 through the coil 3.
af! : The inner permanent magnet 9 is magnetized to generate an inner magnetic flux passing through the main iron core 5a via the coil 3. The outer magnetic flux is generated through a closed magnetic path l consisting of the permanent magnet 8, the air gap 6, the main core 5a, the left side joint portion 5d in FIG. 3(c), and the outer core 5b.
O1, permanent magnet 8, air gap 6, main iron core 5a, and O in Fig. 3
This is the magnetic flux that passes through each of the closed magnetic paths 11 made up of the right side joint portion 5d and the outer core 5b in the IC. The inner magnetic flux is caused by the permanent magnet 9, the air gap 7, the main iron core 5a, and the joint parts 5e, 5e.
This is the magnetic flux passing through each of the closed magnetic paths 12 and 13, which correspond to the closed magnetic paths 1o and ti, respectively, and which are made up of the inner iron core 5C and the inner iron core 5C.

In FIG. 3, since the voice coil motor has the above-mentioned configuration, the coil 3 can be oscillated about the shaft 2 by energizing the coil 3.
As a result, it is possible to provide a multi-rotation torque with multiple loads connected by @2I. Figure 3 IC is a closed magnetic circuit lO~13
is arranged in a plane parallel to the plane of the paper n, but the permanent magnet 8
．． 9 is the front side of the paper.

Closed magnetic circuits 10 to 13 are arranged so that the toe holes on the back side are arranged respectively.
Even if the coil 3I is arranged in a plane perpendicular to the plane of the paper, the oscillating motion of the coil 3I can be made as in the case shown in Fig. 3 σ. However, if the magnets 8.9 are arranged on the front and back sides of the page of FIG. 3 in this way, the thickness of the voice coil motor in the direction perpendicular to the page of FIG. 3 increases.

This results in practical inconveniences for the voice coil motor (σ), and the voice coil motor is usually constructed as shown in Figure 3 (n) and Figure θ) (Fig. θ). However, if the IC voice coil motor is configured like this σ), then Cζ, air gap 6,
At 7? A problem arises in that it becomes difficult to make the magnetic flux density distribution uniform.

FIG. 4 shows a voice coil motor I having the configuration shown in FIG.
Fig. 3 is a cross section corresponding to Fig. 3 of a voice coil motor using an outer permanent magnet 142 and an inner permanent magnet 15, which are magnetized so that the directions of magnetic flux in each part of the magnets are parallel to each other. It is a diagram. XX in the drawing is set so that it passes through the axis of the shaft 2. The fan-shaped tripod core 5r is a virtual axis serving as the central axis. In this case, the outer permanent magnet 14 is formed so that the surface in contact with the outer core 5b and the main core 5al are part of the ring σ so that the opposing surface is on the coaxial cylindrical surface. I'm here. The inner permanent magnet 15 is also formed into a -C shape so that the surface in contact with the inner core 5C and the surface facing the main core 5atC are on coaxial cylindrical surfaces, so that the magnet 15 is part of the C ring. P
is an arrow indicating the direction of internal magnetic flux in the permanent magnet 14-ζ,
Q is an arrow indicating the direction of internal magnetic flux in the permanent magnet 151, and as shown in FIG. 4, tC1 magnet L4.
L5 is magnetized so that the direction of the internal magnetic flux is parallel to the direction of the X-X axis - ζ in all 61 parts of the magnet σ. Y-Y passes through the axis of axis 2 and axis X-X
This is a virtual coordinate line set to form an angle θ with .

FIG. 5 (2) and FIG.

7a, the inertia axis θ in both figures represents each position in the gap 6.7 ζ crossed by the coordinate line Y-Y in FIG. 4. Moreover, θ0 in IC in both figures is determined practically for the voice coil motor shown in FIG. 4. This is the movable range of the coil 3.

As is clear from Fig. 5, the magnetic flux density distribution 6 in the strips and gaps 6
a has a trapezoidal shape with a long base, and the magnetic flux density distribution 7a of the air gap 7 has a semicircular shape, and the air gap 6,7σ]
In any case, the magnetic flux density distribution is not uniform within the movable range θG. Therefore, in the voice coil motor of FIG. 4, the movable range of the coil 3 is θ. However, there is a problem in that it is not possible to generate a uniform torque on the shaft 2Iζ regardless of the position of the coil.

FIG. 6 shows the above-mentioned movable range θ. In each of the air gaps 6°7 (so that the magnetic flux density distributions 6a and 7a are uniform), the outer permanent magnet 16 and the inner permanent magnet 17 are
FIG. 4 is a sectional view corresponding to FIG. 4 of a voice coil motor in which various shapes are set. In this case as well, the permanent magnets 16 and 17 have internal magnetic fluxes that are both parallel magnetic fluxes, and the directions P and Q of these magnetic fluxes are both along the axis X- -C magnetization is carried out so that the direction of X is ζ parallel tζ, but the outer iron core 5b+ of the magnet 16
(hereinafter, this length may be referred to as the thickness of the magnet 16), and the length between the surface in contact with the inner core 5C1 of the magnet 17 and the opposing surface of the main iron core 5a+ζ of the magnet 17. The length between the main iron core 5aI and the opposing surface (hereinafter this length may be referred to as the thickness of the magnet 17) is the length of the magnet 16.17+.

The size is set according to the position from the center axis XX. In other words, the magnets 16 and 17 are formed so that, as shown in FIG. 5, when the magnetic flux density 6a+7a decreases, the thickness of the magnet at this portion increases as the magnetic flux density σ) decreases.

Therefore, in the voice coil motor shown in Fig. 6, Fig. 7 shows the actual measurement results, and each magnetic flux density distribution 6 a t 7 a in the air gaps 6 and 7 I is a rectangle I.
The magnetic flux density distribution 6a+7a is the movable range θ of the coil 3 in any one C of both air gaps 6.7.

It is uniform within.

In the voice coil motor l shown in Fig. 6, the permanent magnet 1
6.17 is formed as described above, so the air gap 6*'
The magnetic flux density distribution at y+C becomes uniform.

Therefore, the coil 3 force movable range θ. The position of the coil within [
Although it is possible to generate a uniform torque on the shaft 2I regardless of the IC, on the other hand, in such a voice coil motor, the thickness of the magnets 16 and 17 must be changed in a complicated manner, making it difficult to manufacture. There is a problem.

[Purpose of the invention]

The present invention solves the above-mentioned problems with the conventional voice coil motor, and the oscillation position of the coil (σ) changes accordingly within the movable range of the coil, that is, within the entire oscillation range of the coil. It is an object of the present invention to provide a voice coil motor that can easily generate a uniform magnetic flux density distribution, in other words, a uniform generated torque.

[Key points of the invention]

In order to achieve the above-mentioned object σ), the present invention provides a coil supported swingably around an axis; a main core disposed so as to pass through the coil; As the coil moves, the coil θ) is placed outside the maximum circle that outlines the
An outer permanent magnet that generates an outer magnetic flux that passes through the main core C through the coil: as the coil swings, the inner magnetic flux that passes through the main core via the coil is placed inside the smallest circle whose outline is drawn by the coil q]. The outer permanent magnet and the inner permanent magnet both have a radial IC magnetization having a center on the side opposite to the coil σ) side with respect to the permanent magnet. By configuring it in this way, the outer permanent magnet and inner permanent magnet are formed to have a uniform thickness over the entire oscillation range of the coil. However, if the magnetic flux density gi of the air gap σ between the outer permanent magnet and the main iron core and the magnetic flux density of the air gap σ] between the inner permanent magnet and the main iron core are the same, regardless of the swinging position of the coil. As a result, a voice coil motor that can easily generate uniform torque over the entire oscillation range of the coil is obtained by distributing the coil in a uniform manner.

[Embodiments of the invention]

FIG. 1 is an explanatory view of the structure of one embodiment of the present invention σ), and this figure is a sectional view corresponding to FIG. 4 or FIG. 6 tC.

The difference from FIG. 4 in this figure is that each internal magnetic flux σ of the outer permanent magnet 18 and the inner permanent magnet 19 is magnetized.
It is the direction. In this case θ), the direction R of the internal magnetic flux in the magnet IC of the outer permanent magnet 18 points to the radiation center point 20 of the axis The number ζ is magnetized so that it is radial around the center. In addition, the inner permanent magnet 19 has an internal magnetic flux σ] direction S centered on a radiation center point 21 on the axis XX, which is on the opposite side of the magnet 191 from the C coil 3 side. It is magnetized in a radial pattern. Magnet 18.
The above-mentioned radial internal magnetic flux at 19+ is generated when forming these magnets.
The thickness of each of the magnets 18 and 19 is uniform with a gap of 6° and 7σ) in each longitudinal direction by applying a parallel strong magnetic field as in the case of magnetizing the magnet. It is formed like this. In other words, magnets 18, 19, like magnets 14115 in FIG.

In the flea cage shown in Fig. 1, the permanent magnets 18 and 19 are magnetized by −c so that each internal magnetic flux becomes radial as described above.
Each magnetic flux density distribution in the air gap 6.7I becomes one as shown in FIG. In other words, FIG. 2 is an explanatory diagram of the actual measurement results corresponding to FIG. 5 or FIG.
The magnetic flux density distribution 6a is shown in FIG.

FIG. 20 shows the magnetic flux density distribution 7a in the air gap 71C. 'w, as is clear from Figure 2, the air gap is 6°71
Each of the magnetic flux density distributions 5a and 7a in this case has a substantially rectangular shape, and both magnetic flux densities correspond to the coil σ) movable range θ. It is uniform inside. Therefore, the voice coil motor shown in FIG. .19 is formed into a ring so that it is part of the ring), making it extremely easy to manufacture. 22°23 in FIG. 1 is the closed magnetic path 1 due to the outer permanent magnet 18)ζ.
The generated outer magnetic fluxes of 0°11 and 24.25 in the figure are the inner magnetic fluxes generated by the ICs of the inner magnets 19I and C closed magnetic circuits 12 and 13, respectively.

In the voice coil motor shown in Fig. 1, as mentioned above, -
Since the magnetic flux density distribution in the air gap 6.7 is close to a rectangle, if the movable range θ0 of the coil 3 is fixed, the length of the magnet 18. The air gap 617 has a uniform magnetic flux density, which can be shortened to make the voice coil motor smaller.
17) There is an advantage that each part can be effectively used.

〔Effect of the invention〕

As described above, the present invention includes a coil supported by an IC that is swingable about an axis; a main iron core disposed to penetrate the coil; an outer permanent magnet that is placed outside the largest circle that outlines the coil and generates an outer magnetic flux passing through the main core through the coil; In a voice coil motor flea, both the outer permanent magnet and the inner permanent magnet are arranged with respect to the permanent magnet. The radial coil with the center on the opposite side of the coil is magnetized. Therefore, the entire swing range of the coil is extended. Even if the outer permanent magnet and inner permanent magnet are formed with a uniform thickness.

The air gap σ between the outer permanent magnet and the main iron core] magnetic flux density and the air gap σ between the inner permanent magnet and the main iron core] magnetic flux density are the same ζ, and the IC distribution is uniform regardless of the swing position IC of the coil. As a result, a voice coil motor that can easily generate uniform torque over the entire swing range of the coil can be obtained.

[Brief Description of the Drawings] Figure 1 is a cross-sectional view for explaining the configuration of one embodiment of the present invention σ);
The figure is an explanatory diagram of the experimental results in the example shown in Fig. 1, and Fig. 2 (Fig. 2) and (2) are different explanatory diagrams. Figure 3 is a general configuration diagram of a conventional voice coil motor.
) is a side view, and FIG. 0 is a Z-Z sectional view of the same figure. Figures 4 and 6 show the first part of the voice coil motor.
Cross-sectional views corresponding to FIG. 3 a1 in the conventional example and the second conventional example, and FIGS. 5 and 7 are experiments in each voice coil motor shown in FIG. 4 and FIG. In the result explanatory diagram, Fig. 5 and Fig. 7 θ] IC
The prisoner diagram and Figure 0 in FIG. 2 are explanatory views corresponding to the prisoner diagram and Figure 0 in FIG. 2, respectively. 2...Axis, 3...Coil, 5a
...Main iron core, 8°14.16. ts...
・・Outer permanent magnet, 9.15.17°19・・・・・・
Inner permanent magnet, 22.23... River/outer magnetic flux, 24, 2
5...Inner magnetic flux. Figure 3 (A”)

Claims (1)

[Claims] a coil supported so as to be swingable about a single axis; a main core disposed so as to pass through the coil; a main core disposed outside the largest circle that outlines the coil as the coil swings; , an outer permanent magnet that generates an outer magnetic flux that passes through the main core via the coil; and an outer permanent magnet that is disposed inside the smallest circle that outlines the coil as the coil swings; an inner permanent magnet that generates an inner magnetic flux passing through an iron core, wherein both the outer permanent magnet and the inner permanent magnet are radially magnetized with centers on a side opposite to the coil with respect to the permanent magnet. A voice coil motor characterized by: