JP2000224829A - Linear vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an actuator at a low cost by reducing a gap of a magnetic circuit of simple constitution. SOLUTION: A linear vibration actuator 10 is equipped with a first magnetic material yoke 12 which has both end portions 12a, 12a and a central part 12b lower than the end portions and forms an almost E-shaped section, an exciting coil 14 wound around the central part 12b of the yoke 12, a second magnetic material yoke 16 which magnetically couples with both end portions 12a, 12b of the first yoke 12, and closes the gap of a magnetic circuit and has an I- shaped section; and a movable magnet body 20 arranged in a magnetic air gap 18 formed by the first yoke 12 and the second yoke 16. By this constitution, a gap does not exist in the magnetic circuit formed by the first yoke 12 and the second yoke 16, so that magnetic resistance is decreased and the amount of a magnet moving in the magnetic air gap 18 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear vibration actuator, and more particularly to a linear vibration actuator which can be used for a vibration alarm of, for example, a pager or a portable telephone.

[0002]

2. Description of the Related Art A typical example of a conventional linear vibration actuator 1 is a movable permanent magnet type shown in FIG. That is, the vibration actuator 1 includes a first magnetic yoke 3 having an E-shaped
And a second magnetic yoke 5 having an I-shaped cross section disposed through the gaps 4, 4, and a permanent magnet disposed in a magnetic gap 7 of the fixed portion 6. And a movable part 8. When a current is applied to the exciting coil 2, a magnetic flux as shown is generated and the electromagnet of the SNS pole is formed as shown in FIG. Such thrust is generated.

[0003]

However, according to the above-described structure, the magnetic structure composed of the first magnetic yoke 3 having the exciting coil 2 and having the E-shaped cross section and the second magnetic yoke 5 having the I-shaped cross section is provided. FIG. 8 shows an equivalent circuit of the magnetic circuit when a gap exists in the circuit and the magnetic flux is maximized. In order for this gap to be a magnetic resistance, it is necessary to increase the amount of magnets constituting the movable part 8. As a result, the amount of expensive magnets must be increased, and there is a problem that the overall cost increases.

[0004] Therefore, a main object of the present invention is to provide an inexpensive linear vibration actuator which has a simple structure and reduces the gap of a magnetic circuit.

[0005]

According to the present invention, a first magnetic yoke having a substantially E-shaped cross section having both ends and a central portion is magnetically coupled to at least one of both ends of the first magnetic yoke. A second magnetic yoke, an exciting coil wound around a central portion of the first magnetic yoke, and a first magnetic yoke and a second magnetic yoke;
And a movable magnet disposed in a magnetic gap formed between the magnetic vibrator and the magnetic yoke.

[0006]

The gap of the magnetic circuit formed by the first magnetic yoke and the second magnetic yoke is closed, for example, by the second magnetic yoke, so that the magnetic resistance is reduced. Therefore, the amount of the movable magnet required to obtain the same amount of magnetic flux can be reduced.

[0007]

According to the present invention, since the gap of the magnetic circuit can be reduced by a simple structure, the amount of movable magnets is also reduced. As a result, a low-cost linear vibration actuator can be provided. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a linear vibration actuator 10 according to an embodiment of the present invention includes a first magnetic yoke 12 having a substantially E-shaped cross section, an exciting coil 14 mounted on the first magnetic yoke 12, and a first magnetic yoke. A fixed portion including a second magnetic yoke 16 magnetically coupled to the body yoke 12 to form a magnetic circuit without a gap, and a magnetic gap 18 formed by the first magnetic yoke 12 and the second magnetic yoke 16 And a movable part including the movable magnet body 20 to be arranged.

The first magnetic yoke 12 has two end portions 12a,
12a and a central portion 12b which is lower than both end portions, and the exciting coil 14 is wound around the central portion 12b. The second magnetic yoke 16 is a flat plate having a substantially I-shaped cross section, and is magnetically coupled to both ends 12a of the first magnetic yoke 12 to form a magnetic circuit. FIG. 2 shows an equivalent circuit of this magnetic circuit.

On the other hand, the movable magnet body 20 disposed in the magnetic gap 18 formed by the first magnetic yoke 12 and the second magnetic body 16 has a pair of permanent magnet pieces 20a having magnetization vectors that are opposite in the radial direction. And 20b are joined side by side in the axial direction. More specifically, as shown in FIG. 3, the movable magnet body 20 accommodates rod-shaped permanent magnet pieces 20a and 20b joined to each other in a cylindrical bobbin 22 formed of a non-magnetic material, as shown in FIG. 2 springs 2
4 and 24, it is disposed in the magnetic gap 18 while being pressed and held between both ends.

In the above configuration, when a current is applied to the exciting coil 14, a magnetic flux generated by the current in accordance with the direction of the current strengthens one side of the adjacent permanent magnet pieces 20a and 20b constituting the movable magnet body 20. In order to weaken the other side, a force that moves the movable magnet body 20 acts on the side where the magnetic flux is strengthened, and the movable magnet body 20 is displaced rightward or leftward. For example, in FIG.
It becomes a pole electromagnet and a rightward thrust acts on the movable magnet body 20. Next, when the direction of the current flowing through the exciting coil 14 changes, the polarity of the electromagnet becomes the N-S-N pole and the movable magnet 20
Has a left thrust. When the direction of the current alternates, the movable magnet body 20 vibrates left and right.

More specifically, when the movable magnet body 20 is housed in a cylindrical bobbin 22 and arranged in the magnetic gap 18 as shown in FIG. 3, the permanent magnet pieces 20a and 20b integrated by joining are left and right. Vibrates linearly. This vibration action can be used, for example, as a vibration alarm for notifying an incoming call of a pager or a mobile phone. In addition, the first shown in FIG.
A modification of the embodiment will be described. In this modified example, both ends 12a of the first magnetic yoke 12 are
At the same height, both ends of the second magnetic yoke 16 are bent to form a U-shaped cross section provided with protrusions 16a, 16a, and both ends of the protrusions 16a, 16a and the first magnetic yoke 12 are formed. 12a, 12a are magnetically coupled to form a gapless magnetic circuit. Then, as in the first embodiment, the movable magnet body 20 is disposed in the magnetic gap 18. The other configuration is the same, and the same figure number is assigned and the description is omitted.

Next, a second embodiment shown in FIG. 5 will be described. In this embodiment, one end 12a of both ends 12a of the first magnetic yoke 12 is maintained at the same height, and the other end 12a is connected to the center 12b around which the exciting coil 14 is wound. Make them the same height. As a result, the second magnetic yoke 16 having an I-shaped cross section is connected to the first magnetic yoke 1.
2 is magnetically coupled with one end 12a to close the gap of the magnetic circuit, but has a gap with the other end 12a. In this case, since there are two magnetic paths, the movable magnet body 20 may have the same size as that of the first embodiment even if one side remains a gap. Then, for example, a pin 26 is connected to the end of the movable magnet body 20 on the gap side, and a piston or a diaphragm (not shown) is connected to the pin 26 and linearly reciprocatingly driven in the left and right directions enables a pumping operation.

FIG. 6 shows a modification of the second embodiment. In this modification, both ends 12a, 12a of the first magnetic yoke 12 and the central portion 1 around which the exciting coil 14 is wound.
With the height of 2b being the same, one end of the second magnetic yoke 16 is bent to provide a projection 16a to form an L-shaped cross section.
2a is magnetically coupled to one end 12a. Also in this case, a pin 26 is attached to the end of the movable magnet body 20 on the gap side.
, And a piston or the like is connected to this pin, so that a pump action can be performed in the same manner as described above.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing a schematic configuration of a linear vibration actuator according to an embodiment of the present invention;

FIG. 2 is an equivalent circuit diagram of the embodiment shown in FIG.

FIG. 3 is an illustrative view showing a specific structure of a movable magnet body in the embodiment of FIG. 1;

FIG. 4 is an illustrative view showing a modified example of the embodiment shown in FIG. 1;

FIG. 5 is an illustrative view showing a second embodiment of the present invention;

FIG. 6 is an illustrative view showing a modified example of the second embodiment shown in FIG. 5;

FIG. 7 is an illustrative view showing a schematic configuration of a conventional movable magnet type linear vibration actuator.

8 is an equivalent circuit diagram of the conventional example shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Moving magnet type linear vibration actuator 12 ... 1st magnetic body yoke 12a ... Both ends 12b ... Central part 14 ... Excitation coil 16 ... 2nd magnetic body yoke 16a ... Projection part 18 ... Magnetic gap 20 ... Movable magnet body 22 ... Tube Bobbin 24… spring 26… pin

Claims (7)

[Claims] A first magnetic yoke having a substantially E-shaped cross section having both ends and a central portion; a second magnetic yoke magnetically coupled to at least one of the both ends of the first magnetic yoke; An exciting coil wound around the central portion of the first magnetic yoke; and a movable magnet body disposed in a magnetic gap formed between the first magnetic yoke and the second magnetic yoke. , Linear vibration actuator. 2. The linear vibration actuator according to claim 1, wherein said first magnetic yoke has both end portions projecting from said central portion. 3. The linear vibration actuator according to claim 2, wherein said second magnetic yoke has a substantially I-shaped cross section. 4. The linear vibration actuator according to claim 1, wherein said both end portions and said central portion of said first magnetic yoke have the same height, and said second magnetic yoke has a substantially U-shaped cross section. 5. The linear vibration actuator according to claim 1, wherein said both ends and said central portion of said first magnetic yoke have the same height, and said second magnetic yoke has a substantially L-shaped cross section. 6. The first magnetic yoke has one end protruding from the other end having the same height as the central part, and the second magnetic yoke has a substantially I-shaped cross section. The linear vibration actuator according to claim 1, wherein the linear vibration actuator has a shape. 7. The movable magnet body includes a cylindrical bobbin, a permanent magnet disposed in the bobbin, and pressed and held by two springs so as to be sandwiched from both ends.
The linear vibration actuator according to any one of the above.