JP2015027176A - Excitation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excitation device which enables low height form and inhibits excess stress on a piezoelectric element.SOLUTION: An excitation device includes: a first conductor plate 2 having a rectangular shape; a support part 3 which supports both longitudinal end parts of the first conductor plate 2; a flat plate-like piezoelectric element 4 fixed to one of main surfaces of the first conductor plate 2; a connection part 5 which is formed in at least a part of a side surface of the first conductor plate 2 which is arranged parallel to a longitudinal direction; and a weight 6 which is connected with the connection part 5.

Description

  The present invention relates to a vibration exciter that propagates vibration to an attached object.

  In mobile devices such as mobile phones, attempts have been made to notify a user of a signal or the like by vibration. In order to make such notification, a technique for transmitting vibration using a piezoelectric element is known.

  Patent Document 1 proposes a piezoelectric vibration device in which a weight is attached to a piezoelectric element attached to the surface of a diaphragm.

JP 07-213997 A

  Mobile devices often receive impact force such as dropping, and the vibration device inside the mobile device receives such impact force, which reduces the ability to generate vibration when the piezoelectric element is damaged. there's a possibility that.

  FIG. 4 is a cross-sectional view illustrating a conventional vibration apparatus. A conventional vibration device 11 as described in Patent Document 1 includes a piezoelectric element 14 attached to both main surfaces of a circular flat conductor plate 12, a weight 16 attached to the piezoelectric element 14, and a conductor plate. The support part 13 which supports the both end surfaces of 12 longitudinal directions is provided, and is accommodated in a case (not shown).

  In the conventional configuration in which a weight is attached to a piezoelectric element, the area required for mounting a vibration device inside a recent smartphone or the like increases, so the shape of the conductor plate with the piezoelectric element attached is circular. Instead, it is desirable to make it rectangular. However, if the shape of the conductor plate is rectangular, the displacement of the weight and the piezoelectric element is almost the same, so when subjected to external impact force, excessive stress is generated in the piezoelectric element and the piezoelectric element is damaged. There is a problem that there is a possibility of doing.

  In addition, there is a problem that it is difficult to reduce the height of the vibration exciter in the configuration in which the weight is overlapped with the conventional piezoelectric element.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vibration exciter capable of reducing the height and suppressing excessive stress on the piezoelectric element.

  According to the present invention, the first conductor plate having a rectangular shape, the support portion for supporting both ends in the longitudinal direction of the first conductor plate, and the at least one main surface of the first conductor plate are fixed. A flat plate-shaped piezoelectric element, a connecting portion formed on at least a part of a side surface parallel to the longitudinal direction of the first conductor plate, and a weight connected to the connecting portion. A vibration device is obtained.

  In addition, it is preferable that the first conductor plate is bent by bending vibration of the piezoelectric element, and the connecting portion is formed at a position where the amplitude of the first conductor plate is maximized.

  The second conductor plate further includes a rectangular second conductor plate, the first conductor plate is connected to the second conductor plate via the connecting portion, and the weight is at least of the second conductor plate. It may be fixed to one main surface.

  Further, it is desirable that the support portion is an elastic body.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the vibration apparatus which can be reduced in height and suppressed the excessive stress to a piezoelectric element.

The top view which shows an example of embodiment which concerns on the vibration apparatus of this invention. It is sectional drawing which shows an example of embodiment which concerns on the vibration apparatus of this invention, and is sectional drawing of the AA line of FIG. Sectional drawing explaining operation | movement of the vibration apparatus of this invention. Sectional drawing explaining the conventional vibration apparatus.

  FIG. 1 is a top view showing an example of an embodiment according to the vibration device of the present invention. FIG. 2 is a cross-sectional view showing an example of an embodiment according to the vibration device of the present invention, and is a cross-sectional view taken along line AA of FIG.

  As shown in FIGS. 1 and 2, the vibration exciter 1 according to the present embodiment includes a rectangular first conductor plate 2, a support portion 3 that supports both longitudinal ends of the first conductor plate 2, The plate-like piezoelectric element 4 fixed to the main surface of the first conductor plate 2, the connecting portion 5 provided at the center of the side surface parallel to the longitudinal direction of the first conductor plate 2, and connected to the connecting portion 5 A weight 6 is provided. The vibration device 1 is accommodated in a case (not shown) by a support portion 3 and connected to a circuit board (not shown) together with a drive electrode (not shown) and fixed.

  When the vibration device 1 is driven, the piezoelectric element 4 expands and contracts, and the first conductor plate 2 generates flexural vibration. The weight 6 vibrates with this bending vibration, the inertial force propagates to the circuit board through the support portion 3, and the circuit board and the attached housing vibrate.

  If the portable device including the circuit board is configured, the vibration device 1 causes the portable device to vibrate, so that the user can perceive the vibration.

  In order to comfortably give vibration to the user by the vibration device 1, the frequency of vibration is preferably 300 Hz or less at which noise due to vibration is not uncomfortable, 100 Hz or less at which noise is hardly audible, or 20 Hz or less (below the audible range) 0 is not included).

  In the present embodiment, a plate-like piezoelectric element 4 is attached to the center of one main surface of the first conductor plate 2 to constitute a piezoelectric unimorph. The piezoelectric elements 4 may be formed on both main surfaces of the first conductor plate 2 to form a piezoelectric bimorph.

  The support 3 is preferably an elastic body such as a silicone resin. Since the support portion 3 is made of an elastic body, the Q value of vibration during the driving of the piezoelectric element 4 is lowered, so that the piezoelectric element 4 in the vibrating device 1 is prevented from resonating and driven to the piezoelectric element 4. The response time until the piezoelectric element 4 stops after stopping the signal can be shortened.

  A connecting portion 5 is provided on a side surface parallel to the longitudinal direction of the first conductor plate 2, and a weight 6 is connected to the connecting portion 5. The piezoelectric element 4 and the weight 6 fixed to the first conductor plate 2 are arranged side by side on the same plane via the connecting portion 5 and have an H-shaped configuration when viewed from above. By adopting this configuration, it is possible to reduce the height as compared with the conventional configuration in which the piezoelectric element and the weight are overlapped.

  FIG. 3 is a cross-sectional view for explaining the operation of the vibration exciter according to the present invention. As shown in FIG. 3, when a driving voltage is applied to the piezoelectric element 4, the piezoelectric element 4 expands and contracts and bends and vibrates together with the first conductor plate 2. This bending vibration is transmitted to the weight 6 through the connecting portion 5, and the weight 6 vibrates. By adopting such a configuration, the vibration of the first conductor plate 2 to which the piezoelectric element 4 is attached is small, but the vibration of the weight 6 is large. The inertial force at the part increases.

  Further, when an impact force is applied from the outside, the vibration of the weight 6 is large, but the piezoelectric element 4 does not bend greatly, so that it is possible to suppress excessive stress on the piezoelectric element 4 and damage the piezoelectric element 4. Can be prevented. Specifically, when a conventional piezoelectric element and a weight are arranged so as to overlap each other, the piezoelectric element may be damaged because a large amplitude flexural vibration is applied to the piezoelectric element. Since the both ends of the first conductor plate to which the piezoelectric element is attached are fixed, a torsional vibration mode in which the piezoelectric element is hardly damaged can be obtained.

  In the present embodiment, the connecting portion 5 is provided on one of the side surfaces parallel to the longitudinal direction of the first conductor plate 2, but the connecting portion is provided on both side surfaces of the first conductor plate 2, and the weight It is also possible to have two. However, it is necessary to optimally design the vibration mode based on the arrangement and quantity of the piezoelectric elements 4 so that the amplitudes caused by the vibrations of the two weights do not cancel each other.

  The connecting portion 5 is preferably formed at a location where the amplitude of the first conductor plate 2 is the largest. In the present embodiment, the connecting portion 5 is the central portion of the side surface parallel to the longitudinal direction of the first conductor plate 2. Considering the vibration mode depending on the arrangement and quantity of the piezoelectric elements 4 attached to the first conductor plate 2, the connecting portion 5 is placed at a position where the amplitude of the first conductor plate 2 is maximized and the vibration is efficiently propagated to the weight 6. It is desirable to design to provide. A plurality of connecting portions 5 may be formed.

  Further, it is desirable that the connecting portion 5 is integrally formed of the same material as that of the first conductor plate 2. It is also possible to provide a rectangular second conductor plate 7, connect to the connecting portion 5, and fix the weight 6 to the main surface of the second conductor plate 7. At this time, the first conductor plate 2, the connecting portion 5, and the second conductor plate 7 can be integrally formed of the same material.

  In the present embodiment, SUS304 is used as the material for the first conductor plate 2, the connecting portion 5, and the second conductor plate 7. However, the present invention is not limited to this. It is desirable to select in consideration of the difference in thermal expansion coefficient, Young's modulus, and the like.

  In the present embodiment, the length of the first conductor plate 2 is 30 mm, the length of the piezoelectric element 4 is 20 mm, and the thicknesses are both 0.2 mm. These dimensions can also be designed as appropriate in consideration of strength, amplitude, and the like, and are not limited thereto.

  In the present embodiment, tungsten is used as the material of the weight 6 in consideration of the specific gravity and cost. However, the material is not limited to this, and it is desirable to design and select such that the amplitude is increased.

  As described above, according to the configuration of the present invention, it is possible to provide a vibration exciter that can reduce the height and suppress excessive stress on the piezoelectric element.

DESCRIPTION OF SYMBOLS 1, 11 Excitation apparatus 2 1st conductor plate 3, 13 Support part 4, 14 Piezoelectric element 5 Connection part 6, 16 Weight 7 2nd conductor plate 12 Conductor plate

Claims (4)

A rectangular first conductor plate;
A support part for supporting both ends in the longitudinal direction of the first conductor plate;
A plate-like piezoelectric element fixed to at least one main surface of the first conductor plate;
A connecting portion formed on at least a part of a side surface parallel to the longitudinal direction of the first conductor plate;
A vibration device comprising a weight connected to the connecting portion. The first conductor plate is bent by the bending vibration of the piezoelectric element,
2. The vibration exciter according to claim 1, wherein the connecting portion is formed at a position where the amplitude of the first conductor plate is maximized. Further comprising a rectangular second conductor plate,
The first conductive plate is connected to the second conductive plate via the connecting portion,
The vibration device according to claim 1, wherein the weight is fixed to at least one main surface of the second conductor plate.   The vibration support device according to claim 1, wherein the support portion is an elastic body.

Images