JP6421090B2 - Piezoelectric vibration actuator - Google Patents

Description

  The present invention relates to a piezoelectric vibration actuator using a piezoelectric element.

  Vibrating actuators are widely used as devices that are built into portable electronic devices and transmit signal generation such as incoming calls and alarms to the mobile phone by vibration, and are indispensable devices for wearable electronic devices that are carried and carried by the mobile phone user. It has become. In recent years, vibration actuators have attracted attention as devices for realizing haptics (skin sensation feedback) in human interfaces such as touch panels.

  Many drive units for vibration actuators have been proposed that use electromagnetic driving force (Lorentz force) obtained by magnets and coils. However, this electromagnetically driven vibration actuator generally has a gap for avoiding contact between a magnet provided on the mover side and a coil provided on the stator side, and a coil thickness for obtaining a sufficient driving force. Therefore, by providing these in a direction intersecting with the vibration direction, various devices are required for thinning.

  On the other hand, a piezoelectric drive type vibration actuator using a piezoelectric element as a drive unit is attached to a vibration plate that elastically deforms a piezoelectric element that generates a vibration force by supplying an electric signal, and a weight is attached to the vibration plate. Since it is mounted (see Patent Document 1 below), the drive unit itself can be formed in a plate shape, so that it can be made relatively thin.

JP 2014-121697 A

  The conventional piezoelectric drive type vibration actuator is a plate-like body whose vibration plate is long in one direction, and a piezoelectric element that expands and contracts along the longitudinal direction is mounted on the plate surface of the vibration plate supported at both ends in the longitudinal direction. Thus, the vibration plate is vibrated in a direction orthogonal to the plate surface. At this time, the weight attached to the vibration plate has a long three-dimensional shape that is fixed at the center of the vibration plate and extends along the longitudinal direction of the vibration plate.

  Such a piezoelectric drive type vibration actuator can be driven relatively stably when the gravity direction and the vibration direction of the weight coincide. However, when the gravity direction of the weight is different from the vibration direction, the weight is twisted due to the gravity of the weight, and the weight attached to the vibration plate against the vibration of the vibration plate due to expansion and contraction of the piezoelectric element. The torsional vibration due to the vibration along the gravity direction is added. As a result, the conventional piezoelectric drive type vibration actuator cannot obtain stable vibration, and there is a problem that the weight contacts the inner surface of the case and generates abnormal noise.

  Since the portable electronic device has various postures depending on the carrying state, the vibration actuator provided in the device also has various postures, and depending on the carrying state, the gravity direction and the vibration direction of the weight may be different. For this reason, as a piezoelectric drive type vibration actuator equipped in a portable electronic device, there is a demand for an apparatus that can obtain stable vibration and does not generate abnormal noise.

  This invention makes it an example of a subject to cope with such a problem. That is, it is an object of the present invention to enable a reduction in thickness by a piezoelectric drive type vibration actuator, to obtain stable vibration even in various postures, and to generate no abnormal noise.

In order to achieve such an object, a piezoelectric vibration actuator according to the present invention has the following configuration.
A weight holder having a pair of diaphragm beam portions that are elongated in one direction and whose plate surfaces are arranged in parallel to each other, and a holding surface that is supported between the pair of diaphragm beam portions and intersects the plate surface A frame, a weight that is held by the holding surface, a frame that supports both ends of the diaphragm beam in the longitudinal direction, and surrounds the diaphragm beam, the weight holder, and the weight; and the diaphragm beam A piezoelectric vibration actuator comprising: a piezoelectric element that is mounted on a plate surface of a portion and vibrates in the direction intersecting the plate surface by extending and contracting along a longitudinal direction thereof.

  The piezoelectric vibration actuator of the present invention having the above-described characteristics enables the thinning, stable vibration even in various postures, and suppression of the generation of abnormal noise. Can do.

It is a disassembled perspective view which shows the piezoelectric vibration actuator which concerns on embodiment of this invention. It is an assembly top view (state which removed the lid frame) of the piezoelectric vibration actuator which concerns on embodiment of this invention. It is an assembly top view (state which removed the lid frame) of the piezoelectric vibration actuator which concerns on other embodiment of this invention. It is an assembly top view (state which removed the lid frame) of the piezoelectric vibration actuator which concerns on other embodiment of this invention. It is a disassembled perspective view which shows the piezoelectric vibration actuator which concerns on other embodiment of this invention. It is an assembly top view (state which removed the lid frame) of the piezoelectric vibration actuator which concerns on other embodiment of this invention. It is explanatory drawing which showed the portable electronic device provided with the piezoelectric vibration actuator which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the X direction of the arrow indicates the longitudinal direction, the Y direction indicates the vibration direction, and the Z direction indicates the thickness direction. Common parts in the drawings are denoted by the same reference numerals, and a part of overlapping description is omitted.

  1 and 2 show a piezoelectric vibration actuator according to an embodiment of the present invention. The piezoelectric vibration actuator 1 includes a pair of diaphragm beam portions 10A and 10B, a weight holding portion 11, a weight 12, a frame body 13, and a piezoelectric element 14.

  Each of the pair of diaphragm beam portions 10A and 10B is long in one direction (X direction in the drawing), and the respective plate surfaces 10S are arranged in parallel to each other. The diaphragm beam portions 10A and 10B are leaf springs supported at both ends in the longitudinal direction by the frame body 13, and the central portion vibrates along the Y direction in the figure by elastic bending vibration.

  The weight holding portion 11 has a holding surface 11S that is supported between the pair of diaphragm beam portions 10A and 10B and intersects the plate surface 10S of the diaphragm beam portions 10A and 10B. In the illustrated example, the holding surface 11S includes a wall surface 11P that is orthogonal to the plate surface 10S of the vibrating beam portions 10A and 10B and rises in the Z direction at both longitudinal edges.

  The weight holding part 11 is provided with a support part 11A at the center part, and the support part 11A is supported by the center part of the diaphragm beam parts 10A and 10B. The weight holding portion 11 and the pair of diaphragm beam portions 10A and 10B can be integrally formed by processing one plate material. Alternatively, the pair of diaphragm beam portions 10A and 10B and the weight holding portion 11 may be formed as separate members and joined together by welding or the like at the support portion 11A to integrate them.

  The weight 12 is held on the holding surface 11 </ b> S of the weight holding unit 11. The weight 12 can be formed of a metal having a high specific gravity such as tungsten. The weight 12 has a three-dimensional shape that is long in the X direction in the figure and thin in the Z direction in the figure. The width in the Y direction is large at the center and small at both ends. Further, the weight 12 is provided with a fixing portion 12A protruding in the width direction (Y direction in the drawing) at the center portion in the longitudinal direction (X direction in the drawing), and the fixing portion 12A is the center of the diaphragm beam portions 10A and 10B. It is fixed to the part. Since the weight 12 is configured in this manner, the weight 12 does not easily come into contact with the diaphragm beam portions 10A and 10B during vibration.

  The frame 13 is a frame that is long in the X direction in the drawing and thin in the Z direction in the drawing, has a bottom surface portion 13A, and includes side wall portions 13B, 13C, 13D, and 13E on the periphery thereof. The side wall portion 13B is provided with support portions 13F that support both end portions of the diaphragm beam portion 10A at both ends thereof, and the side wall portion 13D is supported at both end portions thereof to support both end portions of the diaphragm beam portion 10B. A portion 13G is provided. Here, the support portion 13F is a trapezoidal portion to which both ends of the diaphragm beam portion 10A are fixed, and the support portion 13G is an opening portion for fixing the bracket 10F fixed in advance to both ends of the diaphragm beam portion 10B. It is.

  The frame body 13 includes a lid frame 13X. The lid frame 13X is configured to cover the diaphragm beam portions 10A and 10B, the weight holding portion 11 and the weight 12 by fixing the outer peripheral edge to the upper ends of the side wall portions 13B to 13E.

  In the illustrated example, the piezoelectric element 14 is mounted on the plate surface 10S of the diaphragm beam portion 10A, and expands and contracts along the longitudinal direction (X direction in the drawing) to cross the diaphragm beam portion 10A with the plate surface 10S. Vibrate in the direction of movement. A drive current for obtaining vibration is input to the piezoelectric element 14. The drive current is preferably an alternating current having a resonance frequency set by the elastic coefficients of the diaphragm beam portions 10A and 10B and the mass of the weight 12.

  According to such a piezoelectric vibration actuator 1, the weight 12 can be firmly held on the weight holding portion 11 by adhesion or the like. The weight 12 is fixed to the central portion of the diaphragm beam portions 10A and 10B by two fixing portions 12A. Further, the center of gravity of the weight 12 is disposed between the center portions of the pair of diaphragm beam portions 10A and 10B. Accordingly, the weight 12 is supported by the pair of diaphragm beam portions 10A and 10B, and vibrates in a direction (Y direction in the drawing) intersecting the plate surface 10S of the diaphragm beam portions 10A and 10B. Here, the gravity direction of the weight 12 varies depending on the posture of the piezoelectric vibration actuator 1, but the weight 12 is intermediate between the pair of diaphragm beam portions 10 </ b> A and 10 </ b> B regardless of the gravity direction of the weight 12. Since it is supported at the position, the gravity itself of the weight 12 can be dispersed in the center of each of the pair of diaphragm beam portions 10A and 10B, and the torsion of the diaphragm beam portions 10A and 10B due to the gravity of the weight 12 can be prevented. Can be distributed left and right. Thereby, the stable vibration of diaphragm beam part 10A, 10B and the weight 12 can be obtained.

  Moreover, no matter what direction the gravity direction of the weight 12 is, the gravity direction component of the weight 12 other than the vibration direction (Y direction in the figure) is received by the rigidity of the pair of diaphragm beam portions 10A and 10B. Thus, the weight 12 can be prevented from swinging in a direction different from the vibration direction (Y direction in the drawing). Thereby, it is possible to suppress as much as possible the abnormal noise generated when the weight 12 contacts the frame body 13.

  3 and 4 show another configuration example of the piezoelectric vibration actuator 1 of the present invention. In the example shown in FIG. 3, the piezoelectric element 14 is mounted on each of the diaphragm beam portions 10A and 10B. A drive current is input to the piezoelectric elements 14 attached to the diaphragm beam portions 10A and 10B so that the diaphragm beam portions 10A and 10B vibrate in synchronization in the same direction. In the example shown in FIG. 3, since the piezoelectric elements 14 are mounted on the left and right target positions (outer plate surface 10S) of the diaphragm beam portions 10A and 10B arranged in parallel, the diaphragm beam portions 10A and 10B, respectively. Are synchronized with each other in the same direction, AC currents having opposite phases are synchronized with each other.

  In the example shown in FIG. 4, the piezoelectric elements 14 are mounted on both the front and back surfaces of one diaphragm beam portion 10A. Also in this case, since the driving force applied to the diaphragm beam portion 10A by the two piezoelectric elements 14 needs to be applied synchronously in the same direction, the two piezoelectric elements 14 are mounted at symmetrical positions of the diaphragm beam portion 10A. Each piezoelectric element 14 receives AC currents having opposite phases and synchronized with each other.

  5 and 6 show another configuration example of the piezoelectric vibration actuator 1 of the present invention. In this example, the weight holding portion 11 is divided and supported by each of the pair of diaphragm beam portions 10A and 10B. The weight holding unit 11 is configured by combining divided bodies 11X and 11Y divided into left and right, and a weight 12 is held in the divided bodies 11X and 11Y. Each of the divided bodies 11X and 11Y includes a holding surface 11S and a wall surface 11P, and one divided body 11X (11Y) holds the left and right halves of the weight 12 so as to embrace it. Thereby, the weight 12 can be integrated with the pair of diaphragm beam portions 10A and 10B via the divided bodies 11X and 11Y of the weight holding portion 11, and the vibration of the weight 12 and the diaphragm beam portions 10A and 10B can be stabilized. Can be

  FIG. 7 shows a portable information terminal 100 as an example of a portable electronic device equipped with the piezoelectric vibration actuator 1 according to the embodiment of the present invention. The portable information terminal 100 including the piezoelectric vibration actuator 1 that can obtain a stable vibration and can be thinned and compact in the width direction is unlikely to generate abnormal noise at the start and end of an operation such as an incoming call or an alarm function in a communication function. It can be transmitted to the user with stable vibration. Further, the portable information terminal 100 pursuing high portability or design can be obtained by making the piezoelectric vibration actuator 1 thin and compact in the width direction. Furthermore, since the piezoelectric vibration actuator 1 has a compact shape in which each part is accommodated in a rectangular parallelepiped frame 13 with a reduced thickness, the piezoelectric vibration actuator 1 can be efficiently installed in the thinned portable information terminal 100. . In addition, since the piezoelectric vibration actuator 1 has high impact resistance strength and high durability, it is possible to obtain the portable information terminal 100 that has a long life and hardly breaks down.

  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: Piezoelectric vibration actuator,
10A, 10B: diaphragm beam portion, 10S: plate surface, 10F: bracket,
11: weight holding portion, 11A: support portion, 11S: holding surface, 11P: wall surface,
11X, 11Y: divided bodies,
12: weight, 12A: fixed part,
13: frame body, 13A: bottom face part, 13B-13E: side wall part,
13F, 13G: support part, 13X: lid frame,
14: Piezoelectric element, 100: Portable information terminal

Claims (5)

A pair of diaphragm beam portions that are long in one direction and whose plate surfaces are arranged parallel to each other;
A weight holding part supported between the pair of diaphragm beam parts and having a holding surface intersecting the plate surface;
A weight held by the holding surface;
Supporting both longitudinal ends of the diaphragm beam part, the diaphragm beam part, the weight holding part, and a frame surrounding the weight,
Piezoelectric vibration comprising: a piezoelectric element mounted on a plate surface of the diaphragm beam portion and vibrating the diaphragm plate portion in a direction intersecting the plate surface by extending and contracting along a longitudinal direction thereof. Actuator.   The piezoelectric vibration actuator according to claim 1, wherein the piezoelectric element is attached to one or both of the pair of diaphragm beam portions.   3. The piezoelectric vibration actuator according to claim 1, wherein the piezoelectric element is attached to one surface or both surfaces of the diaphragm beam portion. 4.   The piezoelectric vibration actuator according to claim 1, wherein the weight holding portion is divided and supported by each of the pair of vibration plate beam portions.   A portable electronic device comprising the piezoelectric vibration actuator according to claim 1.

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