JPH0993900A - Oscillation actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an oscillation actuator which produces a high amplitude while reducing the loss in magnetic circuit by employing a moving coil type oscillator comprising a coil, a coil bobbin and a cover. SOLUTION: When a current is fed through a lead wire 51 to first and second coils 43a, 43b, the current flows according to the winding direction of respective coils. Since a magnetic field acts in reverse direction on the first and second coils 43a, 43b, a thrust is generated in same direction from each coil when the current flows in reverse direction. Consequently, an oscillator (cover 40, spindle 41, coil bobbin 42, first coil 43a, and second coil 43b) begins to move. This structure of moving coil reduces the weight of oscillator and the amplitude of oscillation can be increased. Furthermore, the air gap can be decreased and the loss of magnetic circuit is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator, and more particularly to a moving coil type vibration actuator suitable for a drive source of a vibration canceller.

[0002]

2. Description of the Related Art As a vibration actuator,
There is one disclosed in Japanese Patent No. 171578. FIG. 5 is a configuration diagram showing the configuration of the vibration actuator described in Japanese Utility Model Laid-Open No. 1-171578. In FIG. 5, reference numeral 1 is a hollow cylindrical side yoke, and 2 is a hollow cylindrical center yoke in which the outer cylindrical surface is arranged at a constant distance from the inner wall surface of the side yoke.

On the inner wall surface of the side yoke 1, first and second coils 3 and 4 are provided with a predetermined interval. Further, a third coil 5 facing the first coil 3 and a fourth coil 6 facing the second coil 4 are provided on the outer cylindrical surface of the center yoke.

The mover 8 is movably supported in the axial direction in the space between the inner cylindrical surface of the side yoke 1 and the outer cylindrical surface of the center yoke 2, and is made of a non-magnetic material.
In the cylindrical portion of the mover 8 between the first coil 3 and the third coil 5, the first magnet 9 which is magnetized in the radial direction and substantially constitutes the cylindrical surface of the mover 8. However, the cylindrical portion of the mover 8 between the second coil 4 and the fourth coil 6 substantially constitutes the cylindrical surface of the mover 8, and the first magnet 9 forms the magnetizing direction. The second magnets 10 having the opposite positions are provided.

Then, in FIG. 5, as indicated by a broken line, the first coil 3 → the first magnet 9 → the third coil 5 →
Center yoke 2-> fourth coil 6-> second magnet 10->
A magnetic circuit having a magnetic flux that makes one circuit via the second coil 4 → side yoke 1 is formed.

Next, the operation of the above configuration will be described. When a current is applied to the first coil 3, the second coil 4, the third coil 5 and the fourth coil 6 so as to have a magnetic polarity as shown in FIG. Three
-Thrust is generated in the fourth coil 6. Here, since the side yoke 1 and the center yoke 2 are fixed, the mover 8 moves in the arrow A direction and the arrow B direction by the reaction of the thrust.
Move in the direction.

[0007]

However, the vibration actuator having the above structure has the following problems.

There are two magnetic gaps in the magnetic circuit,
Since the gap length of the magnetic gap is large, and the first and second magnets 9 and 10 are arranged through the space with respect to the side yoke 1 and the center yoke 2, the magnetic resistance is large and the loss is large. .

Since the magnetizing direction of the magnet is the radial direction,
In order to obtain a predetermined power, it is necessary to secure a predetermined size in the axial direction, which makes it difficult to reduce the size of the mover. Further, since the structure is such that the first and second magnets 9 and 10 are attached to the groove formed on the cylindrical surface of the mover 8, manufacturing is difficult. Furthermore, because it is difficult to make the mover thinner in the moving direction,
The length of the mover in the moving direction becomes long, and the structure for supporting the mover becomes complicated.

In order to solve these various problems, the applicant of the present application has disclosed, in Japanese Patent Application No. 5-69800, a coil fixed to a housing and a mover having a magnet and a yoke supported by a spindle. We propose a moving magnet type vibration actuator.

However, in such a structure, the mover has a magnet. In this case, since the weight of the mover becomes large, there is a problem that the vibration amplitude cannot be increased when a predetermined input is supplied.

Depending on the application of the vibration actuator, a large amplitude (stroke of vibration) may be required to cancel the vibration of various engines. Therefore, the vibration actuator described above cannot obtain a sufficient amplitude.

The present invention has been made in view of the above problems, and an object thereof is to provide a vibration actuator capable of obtaining a large amplitude with little loss as a magnetic circuit.

[0014]

Means for Solving the Problems The present invention, which is means for solving the problems, is as described below. The present invention has a housing of a magnetic body in the form of a hollow cylinder with a bottom, one end surface of which is open and the other end surface of which has a bottom portion, and a hollow cylindrical portion which is provided at the bottom portion of the housing and extends inside the housing, A spindle movably supported by the inner cylinder of the hollow cylinder, a cover having one end attached to the center of the spindle so as to cover an open end surface of the housing, and a spindle of the housing. In the space between the inner cylindrical surface and the outer cylindrical surface of the hollow cylindrical portion, mounted around the hollow cylindrical portion, a disk-shaped first yoke having a cylindrical cut and raised portion on the outer peripheral portion, In the space between the inner cylindrical surface of the housing and the outer cylindrical surface of the hollow cylindrical portion, the disk-shaped second is attached around the hollow cylindrical portion and has a cylindrical cut-and-raised portion on the outer peripheral portion. A yoke and the first yoke And a ring-shaped magnet magnetized in the axial direction of the spindle and disposed between the housing and the first and second yokes. A coil bobbin attached to the cover, a first coil circumferentially wound on the coil bobbin between the first yoke and the housing, a second yoke and the housing A second coil wound in the opposite direction to the first coil on the coil bobbin between, and a positioning means for positioning the hollow cylindrical portion and the cover so as to be in a predetermined position. It is a characteristic vibration actuator.

In this vibration actuator, a magnetic circuit is formed which goes around one surface of the magnet, the first yoke, the first coil, the housing, the second coil, the second yoke, and the other surface of the magnet. It When a current is applied to the coil in this magnetic circuit, a thrust is generated in the coil and the cover vibrates via the coil bobbin.

In this case, since the moving coil type vibrator including the coil, the coil bobbin and the cover is lighter in weight than the moving magnet type vibrator, a sufficiently large amplitude is generated when a predetermined force is generated. Can occur.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a top view of FIG.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a first embodiment of the present invention. 2 is a front view when viewed from the left side of FIG.

In these figures, the housing 31 is made of a magnetic material in the form of a hollow cylinder with a bottom, one end of which is open. At the bottom of the housing 31, a hollow cylindrical portion 32 extending inside the housing 31 is formed. A bearing 3 is provided on the inner peripheral surface of the center hole of the hollow cylindrical portion 32.
3 is provided, and a spindle 41 described later is provided so as to be movable in the axial direction.

The first yoke 34a has a cylindrical cut-and-raised portion directed toward the open end surface side of the housing 31 on the outer peripheral portion thereof, and has a disk shape with a hole having the same diameter as the hollow cylindrical portion 32 formed in the central portion. The hollow cylindrical portion 32 is made of a magnetic material and is a space between the inner cylindrical surface of the housing 31 and the outer cylindrical surface of the hollow cylindrical portion 32.
It is attached and disposed on the side.

The second yoke 34b has a cylindrical cut-and-raised portion toward the bottom of the housing 31 on the outer peripheral portion, and a disk-shaped magnetic body in which a hole having the same diameter as the hollow cylindrical portion 32 is formed in the central portion. And is attached to the hollow cylindrical portion 32 side so as to be adjacent to the first yoke 34a with a space in the space between the inner cylindrical surface of the housing 31 and the outer cylindrical surface of the hollow cylindrical portion 32. Has been done.

The magnet 35 is provided so as to be sandwiched between a disk-shaped first yoke 34a and a second yoke 34b,
It is magnetized in the axial direction (for example, the yoke 34a side is N pole and the yoke 34b side is S pole).

The first yoke 34a and the second yoke 3
4b and the magnet 35 are attached to the hollow cylindrical portion 32 and the housing 31 by the screws 36a and 36b in the embodiment shown in FIG. 1, but other attachment methods such as adhesion can be used. .

On the open end face side of the housing 31, there is provided a cover 40 having a size enough to cover the open end face and having a spindle 41 mounted in a central hole. Therefore, the cover 40 is movably provided on the open end surface side of the housing 31. The coil bobbin 42 is disposed in the space between the housing 31 and the first yoke 34a and the second yoke 34b, and is attached to the cover 40.

The first coil 43a is circumferentially wound on the cylindrical surface of the coil bobbin. The second coil 43b is arranged on the cylindrical surface of the coil bobbin so as to be adjacent to the first coil 43a with a gap in the axial direction.
It is wound in the opposite direction to 3. The first coil 43a
Is provided so as to face the cut and raised portion of the first yoke 34a, and the second coil 43b is provided so as to face the cut and raised portion of the second yoke 34b.

A bearing 33 is provided on the inner peripheral surface of the center hole of the hollow cylindrical portion 32, and a spindle 41 is provided movably in the axial direction through the bearing 33.
Springs 50a and 50b as positioning means are provided between the cover 40 and the hollow cylindrical portion 32 and between the end of the spindle 41 and the hollow cylindrical portion 32, and are provided with the vibrator (cover 40, spindle 41, coil bobbin 42, The one coil 43a and the second coil 43b) are held so as to be stationary at a predetermined position while maintaining a movable state.

The lead wire 51 supplies a current to the first coil 43a and the second coil 43b, and is led out from the cover 40 side or the housing 31 side. In this figure, it goes through the cover 40.

Therefore, the magnet 35 → the first yoke 34a →
First coil 43a → housing 31 → second coil 4
A magnetic circuit is formed, in which a magnetic flux passes once, such as 3b → second yoke 34b → magnet 35.

Next, the operation of the vibration actuator having the above structure will be described. When a current is passed through the lead wire 51 to the first coil 43a and the second coil 43b, a current flows according to the respective winding directions. In this case,
Electric currents flow in opposite circumferential directions.

Since magnetic fields in opposite directions act on the first coil and the second coil, respectively, currents flowing in opposite directions to each other cause thrust forces in the same direction on both coils according to Fleming's left-hand rule. Occurs.

Then, due to this thrust, the vibrator (cover 40, spindle 41, coil bobbin 42, first coil 43a, second coil 43b) tries to move.
In this case, the first and second coils 43a, 43
By passing an alternating current through b, the oscillator generates vibrations according to the current waveform.

Further, since the moving coil type structure is used, since the vibrator does not include heavy objects such as magnets and yokes, the vibrator becomes light in weight. Therefore, when driven with the same electric power as the moving magnet type vibration actuator, the vibration amplitude (stroke) can be increased.

That is, according to the equation of F = m · α, the power F determines the force F. The moving coil type can reduce the mass m. Therefore, the acceleration α increases. Here, if the frequency of the supplied current is the same as in the conventional case, the cycle of vibration is the same, and therefore the acceleration α increases as the vibration amplitude increases.

When the inventor conducted an experiment and confirmed,
It was confirmed that the moving coil (MC) type vibration actuator of this embodiment requires less input power when the same force F is applied to the outside as compared with the moving magnet (MM) type vibration actuator. This state is shown in FIG.
Note that FIG. 3 shows the case where the vertical axis is in logarithmic scale.

In the same manner, the inventor conducted an experiment and confirmed that the MC type vibration actuator of this embodiment has a vibrator weight of 1/4 to 1/4 that of the MM type vibration actuator.
It could be reduced to 1/5. Therefore, it is possible to obtain a stroke that is 4 to 5 times the same power. Further, it was confirmed that the input required to obtain the same stroke was about 1/4 to 1/5 as shown in FIG. still,
In FIG. 4, a case where the input on the vertical axis is in logarithmic scale is shown.

Therefore, the features of the vibration actuator in this embodiment are summarized as follows. 1. The moving coil type configuration reduces the weight of the vibrator because the vibrator does not include heavy objects such as magnets and yokes. Therefore, when driven with the same electric power as the moving magnet type vibration actuator, the vibration amplitude (stroke) can be increased.

2. Since the vibrator (movable part) is lightweight, it is possible to suppress the loss in the vibrator itself. 3. Since the vibrator (movable part) is lightweight, it has high durability against external vibration and shock.

4. Since the vibrator (movable part) is light in weight, it is possible to realize vibration that closely follows the waveform of the supplied current up to a frequency higher than that of the moving magnet type vibration actuator.

5. The coil heats up due to the current supply,
The movement of the coil itself blows the wind to promote heat dissipation. Particularly, since the vibration amplitude is large as described above, the heat dissipation effect is also large. Further, the fact that the coil is close to the housing 31 and the large surface area of the coil also contributes to increasing the heat radiation effect.

6. Since there is no fixed iron core integrally formed with the coil, there is no problem that a non-excitation holding force works. Therefore, there is no loss and it vibrates faithfully even when a low input is applied.

7. Since the housing 31 and the cut-and-raised parts of each yoke are both stators and can be arranged concentrically around the spindle 41, it is easy to improve accuracy. Therefore, it is possible to reduce the air gap and improve the efficiency. Therefore, there is little loss as a magnetic circuit.

8. Since both the housing 31 and the cut-and-raised portions of each yoke are stators, it is easy to improve accuracy.
Since the coil as the vibrator is lightweight, the possibility that the vibrator and the stator will come into contact with each other due to vibration of the vibrator is small.

9. Since the flat ring magnet magnetized in the axial direction is used as the magnet 35, the vibrator can be made thin. Therefore, it is easy to reduce the thickness of the vibration actuator as a whole.

10. By providing a cylindrical cut-and-raise on the outer peripheral portion of the disk-shaped yoke and allowing the cut-and-raise to face the coil, leakage magnetic flux is reduced and efficiency is improved. Further, it is not necessary to use a magnet magnetized in the radial direction, and it is possible to use a flat ring magnet magnetized in the axial direction.

11. As the flat ring magnet magnetized in the axial direction, a general-purpose product used for a speaker or the like can be used. Therefore, it is possible to reduce the manufacturing cost as compared with a vibration actuator using a magnet magnetized in the radial direction, and it is easy to obtain parts.

12. Since the initial position of the vibrator is determined by a positioning means such as a spring, the vibrator can be reliably held at the magnetic center position (neutral point). Therefore, the efficiency of the magnetic circuit does not decrease. The positioning means may use various elastic members such as a metal or resin diaphragm and a leaf spring.

As described above, according to the vibration actuator of this embodiment, it is possible to realize a vibration actuator which has a magnetic circuit with a small loss and a large amplitude.

[0048]

As described above, the magnet magnetized in the axial direction, the two yokes attached to the magnetized surface of the magnet and having the cut-and-raised portions, and the two yokes and the positions on the outer circumference thereof. According to the vibration actuator composed of a magnetic housing and a vibrator having a coil between the yoke and the housing, a vibration actuator capable of obtaining a large amplitude with little loss as a magnetic circuit is realized. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a vibration actuator according to a first embodiment of the present invention.

FIG. 2 is a front view of the vibration actuator according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between an external force and an input power in the vibration actuator according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between stroke and input power in the vibration actuator according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram showing a configuration of a vibration actuator described in Japanese Utility Model Publication No. 1-171578.

[Explanation of symbols]

 31 housing 32 hollow cylindrical portion 33 bearing 34a first yoke 34b second yoke 35 magnet 36 screw 40 cover 41 spindle 42 coil bobbin 43a first coil 43b second coil 50 spring 51 lead wire

Claims (1)

[Claims] 1. A housing of a magnetic body in the form of a hollow cylinder having a bottom, one end surface of which is open and the other end surface of which is a bottom, and a hollow cylindrical portion which is provided at the bottom of the housing and extends into the housing. A spindle movably supported in an inner cylindrical portion of the hollow cylindrical portion in an axial direction; a cover having one end of the spindle attached to a central portion so as to cover an open end surface of the housing; In the space between the inner cylindrical surface of and the outer cylindrical surface of the hollow cylindrical portion, mounted around the hollow cylindrical portion,
In the space between the disk-shaped first yoke having a cylindrical cut-and-raised portion on the outer peripheral portion, and the inner cylindrical surface of the housing and the outer cylindrical surface of the hollow cylindrical portion, around the hollow cylindrical portion. Installed,
A disk-shaped second yoke having a cylindrical cut-and-raised portion on the outer periphery, and a ring-shaped magnet arranged in the axial direction of the spindle, which is arranged between the first yoke and the second yoke. A magnet, a coil bobbin disposed in the space between the housing and the first yoke and the second yoke, and attached to the cover; and a coil bobbin between the first yoke and the housing. A first coil wound in a circumferential direction with a second coil wound in the opposite direction to the first coil on the coil bobbin between the second yoke and the housing, A vibration actuator, comprising: positioning means for positioning the hollow cylindrical portion and the cover so that they are in a predetermined position.