JP2015157277A - vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smaller vibration actuator which can obtain a high reliability and a high durability and obtain a higher amplitude of vibration by having a mechanism which prevents a movable element in principle from colliding on a housing.SOLUTION: A vibration actuator 1 comprises: a movable element 10, comprising a magnet 2 rotatably supported around an axis, a weight 3 rotatably supported by integration with the magnet 2, and an elastic support member 4 that elastically supports the rotation of the weight 3 and that of the magnet 2; a coil 5 supplied with an AC current having a frequency equivalent to a resonant frequency of the movable element 10; and a magnetic pole member 6 that changes magnetic poles with the AC current flowing through the coil 5 to alternately give rotational torques of different directions to the magnet 2. The movable element 10 is vibrated under rotational reciprocation around the axis.

Description

  The present invention relates to a vibration actuator that generates vibration.

  Portable electronic devices such as mobile phones and personal digital assistants are equipped with a vibration generation function that conveys signal generation such as incoming calls and alarms to the user without making a sound. The device has a built-in vibration actuator.

  As a vibration actuator built in such a portable electronic device, a linear resonance actuator (LRA: Linear Resonant Actuator) is known (see Patent Document 1 below). In the LRA, an alternating current equal to the natural frequency of a weight suspended by a spring is passed through the winding to cause the weight to reciprocate linearly in a linear direction by interaction with the magnet. As a vibration actuator, a DC motor type (ERM: Eccentric Rotating Mass) is also known (see Patent Document 2 below), in which an eccentric weight is attached to a shaft to obtain a swinging vibration. Since it does not have such a contact commutator, it is highly reliable and durable, and is suitable for applications where the operation frequency is high, such as haptics for touch panels in addition to incoming alarms.

JP 2012-016153 A Japanese Patent Laid-Open No. 10-336949

  Since the vibration value of the LRA is determined by the mass of the mover and its vibration amplitude, when trying to obtain the maximum vibration value in a limited space for incorporation in a portable electronic device, the maximum range of the internal space dimension of the housing is reached. The vibration amplitude is set, and the contact between the mover and the housing is inevitable. When the mover and the housing come into contact with each other, a collision sound at that time and a chatter sound due to the collision are generated, and the original purpose of the vibration actuator provided to transmit the signal generation to the user without sound is reduced. Problems that cannot be achieved.

  For this, a cushioning material that softens the generated sound is generally provided between the mover and the housing, but the generated sound cannot be completely eliminated and can be an essential solution. Absent. Further, when trying to avoid contact in terms of structure, the amplitude of the mover is reduced with respect to the internal space of the casing, or the casing is increased with respect to the amplitude of the mover, which is smaller and larger. The request to obtain vibration amplitude cannot be satisfied.

  This invention makes it an example of a subject to cope with such a situation. In other words, by taking advantage of the LRA that does not have a contact commutator in order to obtain high reliability and durability, in principle, a mechanism that does not cause a collision between the mover and the housing can be made smaller and larger. It is an object of the present invention to provide a vibration actuator capable of obtaining vibration amplitude.

In order to achieve such an object, a vibration actuator according to the present invention comprises the following configurations among several inventions described in the specification.
A mover comprising: a magnet rotatably supported around an axis; a weight rotatably supported integrally with the magnet; and an elastic support member that elastically supports rotation of the magnet and the weight; A coil to which an alternating current having a frequency equivalent to the resonance frequency of the mover is supplied, and a magnetic pole member that alternately applies a rotational torque in different directions to the magnet by changing the magnetic pole by the alternating current flowing through the coil, A vibration actuator characterized in that the movable element is reciprocally rotated around the axis.

It is explanatory drawing ((a) is an exploded perspective view, (b) is an external side view) which showed the whole structure of the vibration actuator which concerns on one Embodiment of this invention. It is sectional drawing of the vibration actuator which concerns on one Embodiment of this invention. It is explanatory drawing which showed operation | movement of the drive part of the vibration actuator which concerns on embodiment of this invention. (A) is a non-energized state, (b) is the case where the direction of current flowing through the coil is +, and (c) is the case where the direction of current flowing through the coil is-. It is explanatory drawing which showed the other example of the drive part in the vibration actuator which concerns on embodiment of this invention. It is explanatory drawing which showed the other form example of the vibration actuator which concerns on embodiment of this invention ((a) is a whole sectional drawing, (b) is the perspective view which showed the mainspring spring which is an elastic member. ). It is explanatory drawing which showed the portable electronic device provided with the vibration actuator which concerns on embodiment of this invention.

  The vibration actuator according to the embodiment of the present invention causes the mover to reciprocate and vibrate around the axis, thereby maximizing the vibration amplitude, and even when the vibration amplitude varies, the vibration of the mover is in a constant space. To fit in. As a result, it is possible in principle to prevent the mover from coming into contact with the surrounding casing and generating collision noise and chatter noise. In addition, the vibration actuator according to the embodiment of the present invention provides an AC current having a frequency equivalent to the resonance frequency of the mover by causing the drive unit to reciprocally rotate the mover by alternately applying rotational torque in different directions to the magnet. And a magnetic pole member that changes the magnetic pole by an alternating current flowing through the coil. As a result, high reliability and durability can be obtained as compared with a commutator having contacts such as ERM.

  The vibration actuator according to the embodiment of the present invention having such a feature can be used in principle between the mover and the housing while taking advantage of the LRA having no contact commutator in order to obtain high reliability and durability. By adopting a mechanism that does not cause a collision, it is possible to provide a vibration actuator that is smaller and can obtain a larger vibration amplitude.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view ((a) is an exploded perspective view and (b) is an external side view) showing an overall configuration of a vibration actuator according to an embodiment of the present invention, and FIG. 2 is an embodiment of the present invention. Sectional drawing of the vibration actuator concerning is shown.

  The vibration actuator 1 includes a magnet 2 that is rotatably supported around an axis P, a weight 3 that is rotatably supported integrally with the magnet 2, and an elastic support member that elastically supports the rotation of the magnet 2 and the weight 3. 4 is provided. In the illustrated example, a rotary shaft 11 that is also a mover 10 is rotatably supported by a pair of bearings 12 and 13, and the magnet 2, the weight 3, and the elastic support member 4 are arranged along the rotary shaft 11. The magnet 2 and the weight 3 are fixed to the rotating shaft 11. In addition, one end of a torsion coil spring as the elastic support member 4 is fixed to the weight 3 and the other end is fixed to the housing via the bearing 12, and the mover 10 is an elastic support member when the drive unit described later is not energized. In a state of being suspended by a torsion coil spring 4, reciprocating rotational movement is possible.

The drive unit 20 that reciprocally rotates and vibrates the mover 10 about the axis P includes the magnet 2, the coil 5, and the magnetic pole member 6 that are also part of the mover 10. The coil 5 is supplied with an alternating current having a frequency equivalent to the resonance frequency of the mover 10 from an alternating current generation source 21 connected to the lead terminal 51 of the coil 5. The resonance frequency of the mover 10 is a natural vibration frequency f ₀ determined by the inertia J of the mover 10 and the spring constant k in the torsional direction of the elastic support member 4, and f ₀ = (1 / 2π) · (k / J) It can be calculated by ^1/2 . The magnetic pole member 6 includes a plurality of magnetic pole pieces 60A and 60B facing the magnetic pole of the magnet 2, and alternately applies rotational torque in different directions to the magnet 2 by changing the magnetic pole by an alternating current flowing through the coil 5. It is.

  The coil 5 is held by a coil holding member 50 having a cylindrical portion 50A through which the rotary shaft 11 passes, and is wound around the rotary shaft 11 (axis P) by being wound around the cylindrical portion 50A. The coil 5 is housed in the coil housing portions 61A and 61B of the magnetic pole member 6 (claw poles 6A and 6B) having the magnetic pole pieces 60A and 60B facing the magnet 2, so that the doughnut shape formed by the magnetic pole member 6 is formed. Thus, different magnetic poles are induced in the magnetic pole pieces 60A and 60B by passing a current through the coil 5.

  In the illustrated example, the two magnetic pole members 6 (claw poles 6A and 6B) are inserted and fixed to the inside of the cylindrical portion 50A of the coil holding member 50 so that the magnetic pole member 6 holds the coil. The member 50 is supported. The bearings 12 and 13 that support the rotating shaft 11 to which the magnet 2 and the weight 3 are fixed are fixed to bearing cases 14 and 15, respectively. The bearing cases 14 and 15 are attached to the magnetic pole member 6 (claw poles 6A and 6B). It is fixed by welding. Here, the bearing case 14 is a housing having a space for accommodating the weight 3 and the elastic support member 4 therein, and the space in the bearing case 14 is a vibration space for the weight 3.

  The weight 3 is an eccentric weight having a semicircular shape in plan view, and its outer peripheral surface rotates and oscillates along the inner surface of the bearing case 14 that is a housing. As long as the vibration amplitude changes, the weight 3 and the bearing case 14 that is the housing do not come into contact with each other.

  FIG. 3 shows the operation of the drive unit of the vibration actuator according to the embodiment of the present invention. (A) is a non-energized state, (b) is the case where the direction of current flowing through the coil is +, and (c) is the case where the direction of current flowing through the coil is-. In the illustrated example, the cylindrical magnet 2 is magnetized in one pole in the diametrical direction and has different magnetic poles around the axis P. Not limited to this, the magnet 2 may be magnetized with a plurality of poles along the circumferential direction. On the other hand, a plurality of magnetic pole pieces 60 </ b> A and 60 </ b> B facing the magnetic pole of the magnet 2 are arranged close to each other along the outer periphery of the magnet 2. In the non-energized state shown in (a), the magnetic pole pieces 60A and 60B are not magnetized, but when the current flows through the coil 5, the magnetic pole pieces 60A and 60B are magnetized to different magnetic poles, and the coil 5 is AC By flowing the current, the polarities of the magnetic pole pieces 60A and 60B are reversed depending on whether the current direction is positive or negative, as shown in (b) and (c). The direction of the rotational torque acting on the magnet 2 is reversed by the reversal of the polarity in the magnetic pole pieces 60A and 60B, and the mover 10 is reciprocally rotated around the axis P.

  FIG. 4 shows another example of the drive unit in the vibration actuator according to the embodiment of the present invention. In this example, the magnet 2 is a cylindrical magnet fixed to the rotating shaft 11 and magnetized to one or more poles in the diametrical direction as in the above-described embodiment, but the magnetic pole member 6 surrounds the magnet 2. A plurality of magnetic pole pieces 60 </ b> P and 60 </ b> X that are annular and protrude toward the outer periphery of the magnet 2 are provided. Coils 5P and 5X are individually wound around the magnetic pole pieces 60P and 60X in opposite directions. By applying an alternating current to the coils 5P and 5X, the polarities of the magnetic pole pieces 60P and 60X are reversed depending on whether the current direction is positive or negative. The direction of the rotational torque acting on the magnet 2 is reversed by the reversal of the polarity in the magnetic pole pieces 60P and 60X, and the movable element 10 is reciprocally rotated around the axis P.

  FIG. 5 shows another example of the vibration actuator according to the embodiment of the present invention. In this example, the main spring 4A is an elastic support member 4 that elastically supports the rotation of the magnet 2 (or the mover 10). A cross-sectional view of the overall configuration is shown in (a) and the configuration of the mainspring 4A is shown in (b). The same parts as those in the example shown in FIG. The mainspring 4A is a thin plate-like elastic member wound in a spiral shape, and its inner end 4A1 is fixed to the rotary shaft 11 so as to impart torsional elasticity to rotation in one direction of the rotary shaft 11. The outer end 4A2 is fixed to the bearing 12.

  In the vibration actuator 1 using the mainspring spring 4A as the elastic support member 4, the mainspring spring 4A has high rigidity in a direction other than the rotation direction, so that it is twisted without distortion with respect to the rotation of the rotary shaft 11, and the elastic support member 4 Stable rotational vibration can be obtained with little energy loss. 5 shows an example in which the outer end 4A2 of the mainspring 4A is fixed to the bearing 12. However, the outer end 4A2 may be fixed to a housing (bearing case 14) that supports the bearing 12. . The outer end 4A2 of the mainspring spring 4A extends along the rotary shaft 11 so as to be fixed to the bearing 12 or the bearing case 14.

  FIG. 6 shows a portable electronic device including the vibration actuator according to the embodiment of the present invention. The portable electronic device 100 such as a mobile phone or a personal digital assistant has a high demand for thinning, and the vibration actuator 1 incorporated in the portable electronic device 100 has a large vibration amplitude while being small enough to cope with a limited installation space. What you have is required. The vibration actuator 1 according to the embodiment of the present invention has a high reliability and durability by not having a contact commutator, and is a mechanism in which a collision between the mover 10 and the casing does not occur in principle. Therefore, it is possible to suppress the generation of abnormal noise such as a collision sound and obtain a smaller and larger vibration amplitude. The portable electronic device 100 including the vibration actuator 1 having such a feature can minimize the generation of sound and transmit a signal such as an incoming call or an alarm to the user by vibration and has a large vibration amplitude. Reliable signal transmission becomes possible. In addition, the portable electronic device 100 can be further reduced in thickness.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention. In addition, the above-described embodiments can be combined by utilizing each other's technology as long as there is no particular contradiction or problem in the purpose and configuration.

1: Vibration actuator, 2: Magnet, 3: Weight
4: Elastic support member (torsion coil spring), 4A: Mainspring spring,
5: Coil, 50: Coil holding member,
50A: cylinder part, 51: drawer terminal,
6: Magnetic pole member, 6A, 6B: Claw pole, 60A, 60B: Magnetic pole piece,
61A, 61B: coil housing part,
10: mover, 11: rotating shaft, 12, 13: bearing,
14, 15: bearing case (housing),
20: Drive unit, 21: AC current source,
P: axis

Claims (5)

A mover comprising: a magnet rotatably supported around an axis; a weight that is rotatably supported integrally with the magnet; and an elastic support member that elastically supports rotation of the magnet and the weight;
A coil to which an alternating current having a frequency equivalent to the resonance frequency of the mover is supplied;
A magnetic pole member that alters magnetic poles by alternating current flowing through the coil and alternately applies rotational torque in different directions to the magnet,
A vibration actuator characterized in that the movable element is reciprocally rotated around the axis. The magnet includes different magnetic poles around the axis,
The vibration actuator according to claim 1, wherein the magnetic pole member has a plurality of magnetic pole pieces facing the magnetic pole of the magnet. A rotating shaft supported rotatably by a pair of bearings,
The vibration actuator according to claim 1, wherein the magnet and the weight are arranged along the rotation axis.   The vibration actuator according to claim 3, wherein the elastic support member is a mainspring spring having an inner end portion fixed to the rotating shaft and an outer end portion fixed to the bearing.   The portable electronic device provided with the vibration actuator of any one of Claims 1-4.

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