JPS5899256A - Voice coil motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention is characterized in that a plurality of permanent magnets made of ceramics are mounted along the inner circumference of an outer casing yoke, and a predetermined gap is formed between them and the center yoke. The present invention relates to a voice coil motor in which a uniform radial magnetic flux is applied to a moving coil, and particularly relates to a voice coil motor using a flat plate-shaped permanent magnet.

There are two types of conventional voice coil motors, as shown in FIGS. 1 and 2. In the voice coil motor shown in FIG. 1, the length of the gap is J and the length of the coil portion of the movable coil is increased. - In this type of voice coil motor, two plate-shaped ceramic permanent magnets 1.1 are arranged one above the other and flat against each other. A plate-shaped rear yoke 2 is fixed to the rear end of both permanent magnets 1.1 whose orientations are scooped out, and are connected in a cut-off U-shape.A magnetically conductive material is placed in the center of the rear yoke 2. A center yoke 3 having a circular cross section is fixed in parallel to the permanent magnet 1.l.A plate-shaped front yoke 4 is attached to the front end of both permanent magnets 1.1.
A hole 5 is formed in the center of the front yoke 4 to form a predetermined gap Gt- with the outer periphery of the tip of the center yoke 3. This gap G is formed to have a width that allows the cylindrical moving coil 6 to freely reciprocate.

In a voice coil motor having such a configuration, the rear yoke 2, center yoke 3, and front yoke 4 form a magnetic enclosure using the permanent magnet 1 as a magnetomotive force, and generate a radial uniform magnetic flux in the gap G. That's what I do. When a current flows through the coil portion 7 of the moving coil 6 in this gear G, a fixed thrust force acts on the moving coil depending on the direction of the current.

The movable coil 6 moves forward at the speed of moving into the gear G or moves toward the edge 1.
and move. In this voice coil motor, the coil length of the coil portion 7 is increased to increase the effective moving distance of the movable coil 6.

The other one, that is, the voice coil motor shown in FIG. 2, is the opposite of the voice coil motor described above, in which the coil portion is shortened and the gap is lengthened.

The outer housing yoke 8 of this voice coil motor is formed into a cylindrical shape, and a plurality of CERAOC permanent magnets 9 are arranged along its inner circumference.
is mounted with the four magnetic poles facing inside as shown. This permanent magnet 9 is formed into a cylindrical shape divided into a plurality of arc shapes.

Further, a rear yoke lO is fixed to the rear of the outer housing yoke 8, and a center yoke 11 having a circular cross section is fixed to the center of the rear yoke 10 so as to form a predetermined gap Gt with the permanent magnet. This gap G is formed so that the cylindrical moving coil L can freely move as described above.

In a voice 1:1 motor with such a configuration,
Using a plurality of permanent magnets 9 as a magnetomotive force, an outer ffl yoke 8,
The magnetic ring 10 and the center yoke 11 constitute a magnetic circuit, and a uniform radial magnetic flux is generated in the gap G formed between the inner surface of the permanent magnet 9 and the outer scrap of the center yoke 110. Therefore, with such a configuration, a uniform magnetic flux acts on the entire coil s13 of the moving coil 12, and a forward or backward thrust acts on the moving coil 12 depending on the same current flowing through the coil portion 13. , the permanent magnet 9 has a longer effective travel distance than the moving coil.

Problems with the Old Prior Art The present invention relates to the latter of the two types of voice coil motors mentioned above. This latter voice coil motor has the following problems from a manufacturing standpoint. These are the difficulty of forming arcuate permanent magnets, the radial magnetization of the inertia material that is the raw material for permanent magnets, and the difficulty of mounting permanent magnets.

The permanent magnet attached to the inner periphery of the outer housing yoke is formed by press-molding granular magnetic material into an arc shape or a cylindrical shape. Generally, arc-shaped or cylindrical OS products have larger dimensional distortions than flat-shaped ones.

Therefore, this fired crystal has a large finishing allowance in order to finish it to a predetermined size. However, Jin's IIkIiI
Since i-products are hard and brittle like set items, they cannot be treated by normal means (
For example, since it cannot be processed by cutting, it is generally ground to a predetermined size using a grinder. Of course, the more finishing marks there are, the more processing time it takes! L. Tool wear also increases. Furthermore, if the fired crystal is arcuate or cylindrical, the tool will be special and it will be difficult to adjust the wear of the tool.

This fired crystal is magnetized to become a permanent magnet, but it is extremely difficult to form magnetic poles on the inner and outer peripheries of the cylindrical fired crystal. Therefore, magnetic poles are formed on the inside and outside of the arc-shaped fired crystal. However, since the inside and outside of the arc are asymmetrical, the shape of the ball of the electromagnet used in the 51 magnet is complicated, and the zero strength of the electromagnetic field also needs to be made stronger.

Incidentally, arc-shaped permanent magnets magnetized in this manner have large variations in their characteristics, resulting in poor yields.

If one wishes to obtain a speed proportional to the current in a voice coil motor, it is necessary to use permanent magnets with nearly identical magnetization characteristics.

These permanent magnets are installed along the inner circumference of the outer yoke, but assembling one arc-shaped permanent magnet into a cylindrical shape inside the outer yoke requires work in a narrow pigeon M, and it is difficult to install. It is very difficult to be influenced by other permanent magnets.

Object of the Sugi Invention The structure of the conventional voice coil motor has the above-mentioned drawbacks in manufacturing, and the present invention was made to overcome these drawbacks.

The present invention provides a nine-structure voice coil motor in which permanent magnets can be molded and magnetized easily, have small dimensional distortions, have uniform magnetization characteristics, and have a refreshing shape, and are easy to mount. The purpose is to

4-shot configuration The voice coil motor of the present invention uses flat ceramic permanent magnets with the inner periphery of the outer casing formed in a polygonal shape, and the outer casing yoke and the magnetic circuit having a circular cross section. A predetermined gap between the magnet and the center yoke of the permanent magnet is formed by a plurality of magnetic concentration concentration yokes mounted inside the permanent magnet.

C. Embodiment of the Invention As a specific embodiment of the present invention, an example will be given in which the inner periphery of the outer housing yoke is made into a rectangular shape, and a permanent magnet and a magnetic flux concentration yoke are attached to each feeding can.

Below, regarding this example, #! This will be explained in detail with reference to FIGS. 3 and 4.

The illustrated outer casing yoke 8a is formed into a rectangular shape by assembling flat plate-shaped magnetically permeable materials using a screw cape. Surprisingly, its inner circumference is also square. A flat ceramic permanent magnet 91 and a magnetic flux concentration yoke 9b are mounted on each side of the square inner circumference of the outer housing yoke 8m in an overlapping manner. Each permanent magnet 9m is formed into a rectangular shape with the same dimensions, and is smaller than each side of the outer casing yoke 8a. As shown in the figure, the permanent magnet 91Oia pole has an N pole on the inside and a T-8 pole on the outside that is in close contact with the outer casing yoke 8a. The magnetic flux concentration yoke 9b is made of a magnetically permeable material such as soft iron, and the surface that comes into close contact with the permanent magnet 9m is flat and has the same dimensions as the permanent magnet 9a, and the inside is formed in an arc shape. The part is four magnetic flux concentration yokes 9
b are connected within the outer housing yoke 8a to form a circular hollow. In addition, a rear yoke lOa is fixed to the wks of the outer casing yoke 8a, and a center yoke l1M having a circular cross section is fixed to the center of the rear yoke lOa. A predetermined gap G is formed between the outer circumference of the center yoke lla and the inner circumference of the magnetic flux concentration yoke 9b. This gap G is formed so that the cylindrical moving coil 12a can move freely.

In the voice coil motor having such a configuration, the outer casing yoke is 8 mm long, with 9 m of permanent magnets acting as magnetomotive force.

A magnetic circuit is constituted by the rear yoke 10M, the center yoke 11, and the magnetic flux concentration yoke 9b, and a radial uniform magnetic flux is generated in the gap G. Therefore, the movable coil 12M within the gear G receives a forward or preferential thrust due to the heat transfer of the current, and moves at a speed proportional to the magnitude of the current.

In the voice coil motor configured as described above, unlike the conventional one, a permanent magnet 9a and a magnetic flux concentration yoke 9b are mounted in advance on each side of the outer casing yoke 3m, superimposed on each other, and then each It is possible to assemble the sides using screws or other means.

Effects of the Invention The voice coil motor of the present invention is configured so that a flat ceramic permanent magnet can be used.

As described above, this flat plate-shaped permanent magnet is produced by press-molding and firing granular magnetic material and then grinding it with a grinder to a predetermined size. In this process, the plate-shaped baked crystal has smaller dimensional distortion than the arc-shaped one, so
The finishing allowance can be reduced, the grinding process can be shortened, and the wear force of the tool can be reduced. Moreover, the flat plate does not require any special equipment or special tools during processing.

This fired crystal is magnetized to become a permanent magnet, but since the surfaces that make up the magnetic poles are flat, it is easier to obtain the same magnetization characteristics compared to conventional arc-shaped ones. There is no need to make it into a special shape.

Since the magnetic flux concentration yoke attached to this permanent magnet is made of a magnetically conductive material such as soft iron, cutting is sufficient without the need for grinding. In this way, the present invention has a structure that allows the use of flat plate-shaped permanent magnets, making it possible to obtain a radially uniform magnetic flux in the gap G.

In addition, even when this permanent magnet is attached along the inner circumference of the outer casing yoke, the permanent magnet and the magnetic flux concentration yoke are attached in advance to each side forming the outer casing yoke as described above. By assembling each side, it is easy because there is no need to erect the permanent magnet in a narrow space like in the past.

[Brief explanation of the drawing]

1 and 2 are perspective views showing a conventional voice coil motor, FIG. 3 is a front view showing an embodiment of the present invention, and FIG. 4 is a perspective view of the voice coil motor shown in FIG. 3. It is. 1 + 9 t 9 a...Permanent magnet 2 t 10
r 10g ”' Rear yoke 3 r 11 + lla
...Center yoke 4...Front yoke 5.
... Hole 6 + 12t12a ... Moving coil 7.13 ... Coil ed> 818a ... Outer yoke 9b ... Magnetic flux concentration yoke substitute Salt entry Benzo Nori Chika Kensuke (and 1 other person) Fig. 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A plurality of ceramic permanent magnets are installed along the inner circumference of the outer casing yoke, with the same magnetic pole inside 111, and a plurality of ceramic permanent magnets are installed along the inner periphery of the outer casing yoke, and a plurality of ceramic permanent magnets are installed between the outer casing yoke and a center yoke having a circular cross section that constitutes a magnetic circuit. In the voice coil motor with a gap of A voice coil motor characterized in that a predetermined gap is formed between the magnetic flux concentration yoke and the center yoke. (2. In claim 1, the inner periphery of the outer housing yoke is formed into a square shape, and the permanent magnet and the magnetic flux concentration yoke are respectively attached to each cut in the outer housing yoke.
Voice coil motor with mold.