WO2019021815A1 - Vibrating apparatus and method for driving the same - Google Patents

Abstract

Provided is a vibrating device that can easily generate sounds of a plurality of desired frequencies and can be miniaturized. The vibration device 1 is joined to the first sex plate 2a having the first flat plate portion 2a1, the first connecting portion 2a2 and the joining portion 2a3, and the joining portion 2a3, and the first flat plate portion 2a1 A second elastic plate 2b having a second flat plate portion 2b1 opposed to each other, a piezoelectric vibration element 3 provided on the first flat plate portion 2a1 of the first elastic plate 2a, and the first elastic plate 2a And a mass addition member 8 attached to the The first elastic plate 2a is configured to be able to generate sounds of a plurality of types of frequencies by the vibration of the bending mode, and the frequency of harmonics when only the first flat plate portion 2a1 vibrates in the bending mode The first flat plate portion 2a1 and the connecting portion 2a2 are configured such that sound can be generated by the vibration of the first elastic plate 2a in the bending mode at a frequency different from that of the first flat plate portion 2a1.

Description

Vibration apparatus and driving method thereof

The present invention relates to a vibration device in which a piezoelectric vibration element is fixed to an elastic plate such as a metal plate and a method of driving the same.

Conventionally, various vibrating devices have been proposed as vibrating devices used for the purpose of notifying an incoming call. Patent Document 1 below discloses an example of such a vibration device. In the vibration device described in Patent Document 1, an elastic plate is used which is bent so as to have a U-shape when the metal plate is viewed from the side. The elastic plate has a plate-shaped fixed portion on one side and a plate-shaped vibrating portion on the other side via the bending portion. The vibrating device of Patent Document 1 operates as a vibrator.

Patent Document 2 below discloses a piezoelectric vibration sounding device in which a piezoelectric diaphragm is supported by a cantilever. A weight is attached to the tip of the piezoelectric diaphragm. This piezoelectric vibration sounding device generates bodily sensation vibration or a buzzer sound by the vibration of the piezoelectric diaphragm. When a drive voltage of 1 kHz to 10 kHz is applied, the front end of the piezoelectric diaphragm hardly vibrates due to the weight of the weight, and therefore, the state is almost the same as the state supported by the double support. In this state, the piezoelectric diaphragm resonates to generate a buzzer sound.

International Publication No. 2015/163166 JP-A-8-314467

In recent years, downsizing of the vibration device has been required. The vibration device of Patent Document 1 is described as a vibration device that can be miniaturized. However, Patent Document 1 does not describe at all a configuration for generating a sound.

On the other hand, in a piezoelectric vibration sounding device having a piezoelectric diaphragm as described in Patent Document 2, it is conceivable to generate sound by vibration in the fundamental mode of the piezoelectric diaphragm or its harmonic frequency. Here, in the piezoelectric vibration sounding device, it is often required to generate a sound of 2 kHz or 4 kHz. However, in the conventional piezoelectric vibration sounding apparatus etc., although it was possible to use frequencies such as third and fifth harmonics of the fundamental mode as resonance frequencies, frequencies other than the above specific multiples are regarded as resonance frequencies. It was difficult to do. Therefore, it was difficult to generate sounds of 2 kHz and 4 kHz by one piezoelectric vibration sounding device. In the case where the above requirements are satisfied, for example, it is necessary to separately prepare a case or the like in which the resonance space for resonating the sound is devised. When the above case is used, miniaturization becomes difficult.

An object of the present invention is to provide a vibrating device which can easily generate sounds of a plurality of desired frequencies and can be miniaturized.

Another object of the present invention is to provide a method of driving a vibration device which can easily generate sounds of a plurality of desired frequencies.

The vibration device according to the present invention is a first elastic member having a first flat plate portion including a tip portion, a connecting portion connected to the first flat plate portion, and a joint portion connected to the connecting portion. A second elastic plate including a plate and a second flat plate portion joined to the joint portion of the first elastic plate and facing the first flat plate portion of the first elastic plate; A piezoelectric vibrating element provided on a surface of the first flat plate portion of the first elastic plate on the second elastic plate side, and a piezoelectric vibration element attached to the tip end of the first elastic plate And a mass addition member, wherein the first elastic plate is configured to be able to generate sounds of a plurality of types of frequencies by the vibration of the bending mode, and only the first flat plate portion is generated by the bending mode. The first elastic plate is at a frequency different from the frequency of the harmonics when vibrating. As it is possible to generate sound by vibrating the music mode, the first flat plate portion and the connecting portion is formed.

In the method of driving a vibration device according to the present invention, an input signal is externally inputted to the piezoelectric vibration element of the vibration device configured according to the present invention, and the first elasticity is changed by changing the frequency of the input signal. The vibrations of the board simultaneously generate sounds of different heights.

According to the vibration device of the present invention, it is possible to easily generate sounds of a plurality of types of desired frequencies, and to achieve size reduction.

According to the driving method of the vibration device of the present invention, it is possible to easily generate sounds of a plurality of types of desired frequencies.

FIG. 1 is a perspective view showing the appearance of a vibration device according to a first embodiment of the present invention. FIG. 2 is a side cross-sectional view of the vibration device according to the first embodiment of the present invention. FIG. 3 is an exploded perspective view of the vibration device according to the first embodiment of the present invention. Fig.4 (a) is a side view of the piezoelectric vibration element in the 1st Embodiment of this invention, FIG.4 (b) is a top view of the piezoelectric vibration element in 1st Embodiment. FIG. 5 is a view showing the relationship between the frequency of vibration and the sound pressure in the first elastic plate of the vibration device according to the first embodiment of the present invention. FIG. 6 is a schematic view for explaining the first vibration mode in the present invention. FIG. 7 is a schematic view for explaining a second vibration mode in the present invention. FIG. 8 is a perspective view of a first elastic plate and a second elastic plate in a first modified example of the first embodiment of the present invention. FIG. 9 is a perspective view of a first elastic plate and a second elastic plate in a second modification of the first embodiment of the present invention.

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

It is to be noted that each embodiment described in the present specification is illustrative, and that partial replacement or combination of configurations is possible between different embodiments.

FIG. 1 is a perspective view showing the appearance of a vibration device according to a first embodiment of the present invention. FIG. 2 is a side sectional view of the vibration device according to the first embodiment. FIG. 3 is an exploded perspective view of the vibration device according to the first embodiment.

The vibration device 1 shown in FIGS. 1 to 3 can be used for a notification function by vibration of a portable electronic device, a notification function by sound, and the like. As shown in FIG. 2, the vibration device 1 has a first elastic plate 2 a. The first elastic plate 2a has a first end 2a4 and a second end 2a5. The first end 2a4 is a tip in the present invention. In the present embodiment, in plan view, the direction connecting the first end 2a4 and the second end 2a5 is the longitudinal direction of the first elastic plate 2a.

The vibration device 1 according to the present embodiment is configured such that the first elastic plate 2a vibrates in the first vibration mode and the second vibration mode in the bending mode. This makes it possible to easily generate sounds of a plurality of types of frequencies. The details will be described later.

The vibration device 1 has a second elastic plate 2b connected to the second end 2a5 side of the first elastic plate 2a. More specifically, the first elastic plate 2a has a first bonding portion 2a3 as a bonding portion in the present invention, which is located on the second end 2a5 side. In the first joint portion 2a3, the first elastic plate 2a is joined to the second elastic plate 2b.

The second elastic plate 2b has a third end 2b4 and a fourth end 2b5. The second elastic plate 2b has a second bonding portion 2b3 located on the fourth end 2b5 side. The second elastic plate 2b is joined to the first elastic plate 2a at the second joint portion 2b3. In the present embodiment, the direction connecting the third end 2 b 4 and the fourth end 2 b 5 is the longitudinal direction of the second elastic plate 2 b. The longitudinal direction of the first elastic plate 2a and the second elastic plate 2b is not limited to the above.

In the present embodiment, the first elastic plate 2a is made of SUS304, and the second elastic plate 2b is made of SUS301. The first elastic plate 2a and the second elastic plate 2b may be made of other elastic material such as metal or synthetic resin other than the above. However, as in the present embodiment, the first elastic plate 2a and the second elastic plate 2b are preferably made of metal such as stainless steel. Thereby, it is possible to further suppress the reduction in the strength of vibration in the first elastic plate 2a and the second elastic plate 2b.

The first elastic plate 2a has a first flat plate portion 2a1, a connecting portion 2a2 and the first joint portion 2a3 located between the first end 2a4 and the second end 2a5. The first flat plate portion 2a1 is planar. The tip of the first flat plate portion 2a1 is located at the first end 2a4. The connecting portion 2a2 connects the first flat plate portion 2a1 and the first joint portion 2a3. The tip of the first joint 2a3 is located at the second end 2a5.

On the other hand, the second elastic plate 2b has a second flat plate portion 2b1 located between the third end 2b4 and the fourth end 2b5, and the second bonding portion 2b3. The second flat plate portion 2b1 is planar. The first flat plate portion 2a1 of the first elastic plate 2a and the second flat plate portion 2b1 of the second elastic plate 2b are opposed to each other.

The first elastic plate 2a is bent toward the second elastic plate 2b in the connecting portion 2a2. In the first elastic plate 2a, the connecting portion 2a2 extends from the first flat plate portion 2a1 toward the second elastic plate 2b. The first bonding portion 2a3 extends from the connecting portion 2a2 in a direction away from the first end 2a4. The first bonding portion 2a3 has a surface extending in parallel to the second flat plate portion 2b1 of the second elastic plate 2b. In the plane, the first joint portion 2a3 is joined to the second elastic plate 2b. The first elastic plate 2a and the second elastic plate 2b are preferably joined by welding. Thereby, the bonding strength can be effectively enhanced.

The said welding can be performed by irradiation of a laser beam etc., for example. In addition, joining of the 1st elastic board 2a and the 2nd elastic board 2b is not limited above, For example, you may be fulfilled by the metal for brazing materials, an adhesive agent, etc.

As shown in FIG. 2, the connecting portion 2 a 2 is located between the dashed dotted line A and the dashed dotted line B. Both ends of the connecting portion 2a2 are curved. Note that at least one of both end portions of the connection portion 2a2 may be bent so as to have a corner portion.

The piezoelectric vibrating element 3 is provided on the first flat plate portion 2a1 of the first elastic plate 2a. More specifically, the piezoelectric vibration element 3 is provided on the surface of the first flat plate portion 2a1 on the side of the second elastic plate 2b. The piezoelectric vibrating element 3 is fixed to the first elastic plate 2 a using a suitable adhesive such as a thermosetting resin-based adhesive. The piezoelectric vibrating element 3 has a rectangular plate shape.

FIG. 4A is a side view of the piezoelectric vibration element in the first embodiment. FIG. 4B is a plan view of the piezoelectric vibration element in the first embodiment.

As shown in FIG. 4A, the piezoelectric vibrating element 3 has a piezoelectric layer 4. The piezoelectric layer 4 has a first main surface 4a and a second main surface 4b opposed to the first main surface 4a. The piezoelectric vibrating element 3 is fixed to the first elastic plate from the side of the first main surface 4a.

As indicated by the broken line in FIG. 4B, the first electrode 5a and the second electrode 5b are provided on the second main surface 4b of the piezoelectric layer 4. As shown in FIG. 4A, a third electrode 5c is provided on the first major surface 4a so as to face the first electrode 5a with the piezoelectric layer 4 interposed therebetween. The third electrode 5 c is electrically connected to the second electrode 5 b by a via hole electrode or a connection electrode (not shown) via the side surface of the piezoelectric layer 4.

As a material for forming the piezoelectric layer 4, an appropriate piezoelectric ceramic such as PZT-based ceramic can be used. The first electrode 5a, the second electrode 5b and the third electrode 5c are made of an appropriate metal or alloy. However, the configuration of the piezoelectric vibration element 3 is not particularly limited in the present invention.

By applying an alternating electric field between the first electrode 5a and the third electrode 5c of the piezoelectric vibrating element 3, the piezoelectric vibrating element 3 expands and contracts in the in-plane direction. Along with that, the first elastic plate 2a shown in FIG. 2 vibrates in the bending mode. The vibration of the first elastic plate 2a is transmitted to the second elastic plate 2b via the first bonding portion 2a3. Here, the vibration device 1 is mounted from the second elastic plate 2b side. The vibration of the vibration device 1 propagates from the second elastic plate 2 b to the outside. By setting the frequency of the vibration of the first elastic plate 2a to a frequency at which a person can sense the vibration, a notification function by the vibration or the like is performed. On the other hand, by setting the frequency of vibration of the first elastic plate 2a to a frequency in the audible range, a sound that can be sensed by a person can be generated, and a notification function by the sound or the like is performed.

As shown in FIG. 2, a mass addition member 8 is attached to the first end 2a4 side of the first elastic plate 2a. The first elastic plate 2a is located near the first end 2a4 and has a mounting portion 2a6 to which the mass addition member 8 is attached. In the present embodiment, the mass addition member 8 is welded to the mounting portion 2a6. The mass addition member 8 may be joined to the attachment portion 2a6 by, for example, an adhesive.

By adding the mass addition member 8, the tip mass of the pendulum consisting of the first elastic plate 2a can be increased, and the vibration of the vibration device 1 can be increased. The mass addition member 8 can also adjust the resonance frequency of the vibration device 1. The mass addition member 8 is made of an appropriate metal, a synthetic material of metal and resin, a ceramic or the like. Preferably, the mass addition member 8 is preferably made of a dense metal such as tungsten because of its high mass addition action.

As shown in FIGS. 2 and 3, a circuit board 6 as a circuit unit is provided on the second flat plate portion 2 b 1 of the second elastic plate 2 b. More specifically, the circuit board 6 is provided on the surface of the second flat plate portion 2b1 on the side of the first elastic plate 2a. For the circuit board 6, an appropriate substrate material made of a glass epoxy substrate or a synthetic resin such as polyimide can be used. The circuit board 6 is provided with at least a part of a drive circuit for supplying power to and driving the piezoelectric vibrating element 3.

The circuit board 6 is electrically connected to the piezoelectric vibrating element 3 by the flexible printed wiring board 7. The flexible printed wiring board 7 is configured using a resin film having flexibility, such as thermosetting polyimide. A conductive adhesive, solder or the like can be used to connect the circuit board 6 and the piezoelectric vibrating element 3 to the flexible printed wiring board 7. The flexible printed wiring board 7 has a wiring connecting portion 7 d which connects a portion connected to the circuit board 6 and a portion connected to the piezoelectric vibrating element 3. Here, the flexible printed wiring board 7 has external connection parts 7a1 and 7a2. Furthermore, the flexible printed wiring board 7 includes a first wiring portion 7b to which the circuit board 6 is connected, a second wiring portion 7c to which the piezoelectric vibrating element 3 is connected, a first wiring portion 7b and a second wiring portion 7c. And the wiring connection portion 7d to be connected. The flexible printed wiring board 7 is bent at the wiring connection portion 7 d such that the same main surfaces of the first wiring portion 7 b and the second wiring portion 7 c face each other.

The circuit portion is not limited to the circuit board 6. The circuit portion may form at least a part of a circuit for driving the piezoelectric vibrating element 3. For example, the circuit unit may be formed of a wiring element or the like. Further, the configuration of connection between the circuit portion and the piezoelectric vibrating element 3 is not particularly limited. For example, the circuit portion and the piezoelectric vibrating element 3 may be connected by a lead wire or the like. The vibration device 1 may not necessarily have a circuit unit. In this case, the piezoelectric vibration element 3 may be driven by an input signal from the outside.

The vibration device 1 has a cover member 9. The cover member 9 is provided to accommodate the first elastic plate 2 a to which the piezoelectric vibration element 3 and the mass addition member 8 are attached.

As shown in FIG. 1, the cover member 9 includes a top plate 9a and a first side surface 9b, a second side surface 9c, and a third side surface 9d, one end of which is connected to the top plate 9a. And a fourth side portion 9e. The first side face 9 b and the third side face 9 d face each other. The second side surface portion 9c and the fourth side surface portion 9e face each other.

The first side surface 9b is located on the first end 2a4 side of the first elastic plate 2a. The third side surface 9d is located on the second end 2a5 side. In addition, the cover material 9 does not need to have at least one of the 1st side part 9b and the 3rd side part 9d.

The cover material 9 is made of an appropriate metal or synthetic resin. Preferably, metal is desirable because of its excellent mechanical strength. More preferably, stainless steel is desirable because of its excellent corrosion resistance.

The features of this embodiment are as follows. 1) The first elastic plate 2a is configured to be able to generate sounds of a plurality of types of frequencies by the vibration of the bending mode. 2) At a frequency different from the frequency of the harmonics when only the first flat plate portion 2a1 vibrates in the bending mode, the first elastic plate 2a can generate sound by vibrating in the bending mode The first flat plate portion 2a1 and the connecting portion 2a2 are configured. More specifically, the first elastic plate 2a is configured to vibrate in the first vibration mode and the second vibration mode in the bending mode. As a result, sounds of a plurality of desired frequencies can be easily generated, and miniaturization can be promoted. This is explained below.

As described above, conventionally, in the vibration device, it has been difficult to use a frequency other than a specific multiple, such as the third or fifth harmonic of the fundamental mode, as the resonance frequency. Therefore, it was difficult to generate sounds of 2 kHz and 4 kHz by one vibration device.

FIG. 5 is a view showing the relationship between the frequency of vibration and the sound pressure in the first elastic plate of the vibration device according to the first embodiment.

In the present embodiment, as shown in FIG. 5, it can be seen that the sound pressure is high at 2 kHz and 4 kHz. The first elastic plate is configured to be able to adjust the resonance frequency in the first vibration mode and the resonance frequency in the second vibration mode. The resonant frequency in the first vibration mode is 2 kHz. The resonant frequency in the second vibration mode is 4 kHz. Thereby, in the present embodiment, it is possible to generate sounds of 2 kHz and 4 kHz by one vibration device 1. As described above, by adjusting the resonance frequency in the first vibration mode and the resonance frequency in the second vibration mode, sounds of a plurality of desired frequencies can be generated. The details of the first vibration mode and the second vibration mode will be described using FIGS. 6 and 7 below.

FIG. 6 is a schematic view for explaining the first vibration mode. FIG. 7 is a schematic view for explaining the second vibration mode. 6 and 7, the vibration mode is schematically shown by integrating the first elastic plate and the mass addition member. The fundamental mode in this embodiment refers to the fundamental mode of the first elastic plate to which a mass addition member is added.

As shown in FIG. 6, the first vibration mode is a vibration mode in which only the first flat plate portion 2a1 of the first elastic plate 2a bends and vibrates. The first elastic plate 2a generates sound by harmonics by vibrating in the first vibration mode. In the first vibration mode, the connecting portion 2a2 hardly vibrates. When the first elastic plate 2a vibrates only in the first vibration mode, it is difficult to set both 2 kHz and its doubled 4 kHz as the resonance frequency, for example.

In the present embodiment, the first flat plate portion 2a1 and the connecting portion 2a2 of the first elastic plate 2a are configured so as to be able to vibrate also in the second vibration mode shown in FIG. The second vibration mode is a vibration mode in which the connecting portion 2a2 is bent and vibrated in addition to the first flat plate portion 2a1. The resonant frequency in the second vibration mode is different from the resonant frequency in the first vibration mode. Thus, the first elastic plate 2a can generate a sound by vibrating in the second vibration mode even at a frequency different from the frequency at which the sound can be generated in the first vibration mode.

Here, the dimension along the direction in which each portion of the first elastic plate 2a extends is taken as the length of each portion. The resonance frequency of the second vibration mode can be lowered as the length of the connecting portion 2a2 is increased. On the other hand, the resonance frequency of the second vibration mode can be lowered as the thickness of the connecting portion 2a2 is reduced. Thus, the resonance frequency of the second vibration mode can be easily adjusted by the connecting portion 2a2. The resonance frequency of the second vibration mode may be adjusted to a frequency other than an integral multiple of the resonance frequency of the first vibration mode. That is, in the present invention, the frequency different from the frequency of the harmonic in the case where only the first flat plate portion vibrates in the bending mode may be a frequency other than the multiple of the fundamental mode in the bending mode.

In the present embodiment, in order to generate sound of a desired frequency, the length and thickness of the first flat plate portion 2a1 of the first elastic plate 2a and the connecting portion 2a2 may be adjusted. Therefore, it is possible to easily generate sounds of a plurality of types of desired frequencies. In addition, since it is not necessary to provide a resonance space in which sound resonates in order to perform frequency adjustment, miniaturization can be promoted.

By the way, as shown in FIG. 5, it can be seen that frequencies other than 2 kHz and 4 kHz also cause the sound pressure to increase. Thus, in the present embodiment, sound can be generated by vibration at a plurality of types of frequencies other than the frequency of the multiple of the fundamental mode. Therefore, various notification functions can be performed.

In addition, in the vibration device 1 of the present embodiment, for example, by vibrating the first elastic plate 2a at 250 Hz in the bending mode, a notification function by vibration can also be performed.

As shown in FIG. 6, in vibration of the first elastic plate 2a that generates sound, it is preferable that a node of vibration be located at the attachment portion 2a6. For example, in the present embodiment, in the vibration of the first elastic plate 2a at 2 kHz in the first vibration mode, it is preferable that the node of the vibration be located at the attachment portion 2a6. Similarly, as shown in FIG. 7, in the vibration of the first elastic plate 2a at 4 kHz in the second vibration mode, it is preferable that a node of the vibration be located at the attachment portion 2a6. As a result, the mass addition member 8 is not easily peeled off from the mounting portion 2a6, and the reliability of the vibration device 1 can be enhanced.

As shown in FIG. 2, the first flat plate portion 2a1 of the first elastic plate 2a and the second flat plate portion 2b1 of the second elastic plate 2b face each other. Thereby, the miniaturization of the vibration device 1 can be effectively promoted. In addition, since the vibration device 1 includes the mass addition member 8 attached to the attachment portion 2a6 of the first elastic plate 2a, the vibration of the vibration device 1 can be increased. Therefore, the size of the vibration device 1 required for suitably performing the notification function can be reduced, and the miniaturization of the vibration device 1 can be further advanced.

Here, the mass addition member 8 of the present embodiment has a first main surface 8A located on the first elastic plate 2a side and a second main surface located on the second elastic plate 2b side. And 8B. The first major surface 8A of the mass addition member 8 has a step-like shape. More specifically, the first main surface 8A includes a third flat plate portion 8a, a fourth flat plate portion 8b, and a fifth flat plate portion 8c which are connected with each other via a step.

The mass addition member 8 is attached to the attachment portion 2a6 of the first elastic plate 2a in the fourth flat plate portion 8b. More specifically, in the first elastic plate 2a, the first end 2a4 is disposed near the step. The fourth flat plate portion 8b and the fifth flat plate portion 8c are also connected via another step. The tip of the piezoelectric vibrating element 3 is disposed near the other step. In the present embodiment, the flexible printed wiring board 7 is stacked on the piezoelectric vibrating element 3 so as to reach the above-described tip end of the piezoelectric vibrating element 3.

The height of the step between the third flat plate portion 8a and the fourth flat plate portion 8b is equal to the thickness of the first flat plate portion 2a1 of the first elastic plate 2a. The height of the step between the fourth flat plate portion 8 b and the fifth flat plate portion 8 c is equal to the total thickness of the piezoelectric vibrating element 3 and the flexible printed wiring board 7. Thereby, the miniaturization of the vibration device 1 can be further advanced.

The third flat plate portion 8a is an inclined surface. At least a part of the second main surface 8B is also an inclined surface. Thereby, as the distance from the first end 2a4 of the first elastic plate 2a is increased, the thickness of the mass addition member 8 (the first main surface 8A of the mass addition member 8 and the second main surface 8B of the mass addition member 8) Distance with) is getting thinner. As a result, when the first elastic plate 2 a vibrates, the mass addition member 8 hardly collides with the second elastic plate 2 b and the top plate portion 9 a of the cover member 9. Therefore, the miniaturization can be promoted and the vibration can be increased. The shape of the mass addition member 8 is not limited to the above.

As shown in FIG. 1, the flexible printed wiring board 7 has an external connection portion 7 a 1 and an external connection portion 7 a 2 electrically connected to the outside. The external connection portion 7 a 1 and the external connection portion 7 a 2 protrude sideward than the second elastic plate 2 b and the cover member 9. Therefore, electrical connection with the outside can be easily performed. In addition, the form of the electrical connection with the exterior in the vibration apparatus 1 is not limited above.

In the present embodiment, as described above, the piezoelectric vibration element 3 is driven by the circuit board 6 shown in FIG. The circuit board 6 is configured to change the frequency of the input signal input to the piezoelectric vibrating element 3. Thereby, sounds of different heights can be generated simultaneously or continuously by the vibration of the first elastic plate 2a, and the notification function and the like can be diversified. In addition, the vibration apparatus 1 can generate the sound of multiple types of frequency including 2 kHz and 4 kHz. Therefore, the combination of sounds of different heights can be diversified, and the notification function and the like can be further diversified. Note that the timing of generating a sound and the strength of the sound may be changed by the circuit board 6.

In the method of driving the vibration device according to the present invention, an input signal is inputted from the outside to the piezoelectric vibration element 3 and the frequency of the input signal is changed to generate sounds of different heights according to the vibration of the first elastic plate 2a. May be generated simultaneously. Further, as a driving method of the vibration device of the present invention, a driving method may be employed in which sounds of different heights are continuously generated by changing the frequency of an input signal from the outside. Note that the timing of generating a sound and the strength of the sound may be changed by inputting an input signal from the outside. According to this driving method, it is possible to easily generate sounds of a plurality of desired frequencies. Even when the vibration device 1 does not have the circuit board 6 or when the circuit substrate 6 does not input an input signal for the vibration device 1 to generate a sound to the piezoelectric vibration element 3, the notification function etc. are diversified. be able to.

The flexural rigidity of the second elastic plate 2b shown in FIG. 2 is preferably higher than the flexural rigidity of the first elastic plate 2a. In addition, bending rigidity means the property which shows the difficulty of performing bending deformation of an object, when force is added to an object. High bending stiffness means that bending deformation is difficult. In the present embodiment, since the second elastic plate 2b has higher bending rigidity than the first elastic plate 2a, the second elastic plate 2b is not easily bent by the vibration of the first elastic plate 2a. Therefore, the intensity of the vibration propagated to the second elastic plate 2b is not easily attenuated. Therefore, even if the thickness and size of the device are reduced, the reduction in vibration intensity is unlikely to occur, and the notification function by the vibration can be suitably performed.

In the present embodiment, the thickness of the second elastic plate 2b is thicker than the thickness of the first elastic plate 2a. Furthermore, the material of the second elastic plate 2b has higher bending rigidity than the material of the first elastic plate 2a. Thereby, the bending rigidity of the 2nd elastic board 2b is higher than the bending rigidity of the 1st elastic board 2a.

The first elastic plate 2a and the second elastic plate 2b may be made of the same material. In this case, the bending rigidity of the second elastic plate 2b can be made higher than the bending rigidity of the first elastic plate 2a by making the thickness or the like different. Alternatively, the thicknesses of the first elastic plate 2a and the second elastic plate 2b may be the same. In this case, the bending rigidity of the second elastic plate 2b can be made higher than the bending rigidity of the first elastic plate 2a by changing the material or the like.

The portion where the first elastic plate 2a and the second elastic plate 2b are joined is the second end 2a5 of the first elastic plate 2a and the fourth end 2b5 of the second elastic plate 2b. It is preferable to include at least one of them. Thereby, miniaturization of the vibration device 1 can be promoted. However, as in the present embodiment, it is more preferable that the portion to which the first elastic plate 2a and the second elastic plate 2b are joined includes both the second end 2a5 and the fourth end 2b5. preferable. Thereby, the miniaturization of the vibration device 1 can be further advanced.

In the following FIGS. 8 and 9, vibration devices according to first and second modified examples of the first embodiment are shown. In the vibration devices according to the first and second modifications, similarly to the vibration device 1 of the first embodiment, sounds of a plurality of desired frequencies can be easily generated, and Miniaturization can be promoted. In addition, in FIG.8 and FIG.9, only the structure of the 1st elastic board of a vibrating device and a 2nd elastic board is shown.

FIG. 8 is a perspective view of a first elastic plate and a second elastic plate in a first modified example of the first embodiment.

The present modification differs from the first embodiment in that the thickness of the second flat plate portion 12b1 of the second elastic plate 12b is thinner than the thickness of the second bonding portion 12b3. Since the thickness of the second flat plate portion 12b1 is smaller than the thickness of the second bonding portion 12b3, the mass addition member hardly collides with the second elastic plate 12b during vibration. Therefore, it is hard to produce the fall of the intensity of vibration accompanying size reduction and thickness reduction.

FIG. 9 is a perspective view of a first elastic plate and a second elastic plate in a second modified example of the first embodiment.

The present modification differs from the first embodiment in that in the first elastic plate 22a, the first bonding portion 22a3 extends from the connecting portion 22a2 in a direction approaching the first end 22a4. More specifically, the first bonding portion 22a3 has a surface extending parallel to the second flat plate portion 2b1 of the second elastic plate 2b. The first bonding portion 22a3 is bonded to the second elastic plate 2b at the surface. The first bonding portion 22a3 has a portion overlapping the first flat plate portion 22a1 in plan view. Therefore, the miniaturization of the vibration device can be promoted.

DESCRIPTION OF SYMBOLS 1 vibration apparatus 2a 1st elastic board 2a1 1st flat plate part 2a2 ... connection part 2a3 1st junction part 2a4, 2a5 ... 1st, 2nd edge part 2a6 ... attachment part 2b ... 2nd Elastic plate 2b1 Second flat plate portion 2b3 Second joint portion 2b4, 2b5 Third and fourth end portion 3 Piezoelectric vibrating element 4 Piezoelectric layer 4a and 4b First and second main surfaces 5a to 5c: first to third electrodes 6: circuit board 7: flexible printed wiring boards 7a1, 7a2: external connection parts 7b, 7c: first and second wiring parts 7d: wiring connection part 8: mass addition member 8A , 8B: first and second main surfaces 8a to 8c third to fifth flat plate portions 9 cover material 9a top plates 9b to 9e first to fourth side surface portions 12b second elasticity Plate 12b1 Second flat plate portion 12b3 Second joint portion 22a First elastic plate 22a1 First flat plate portion 22a2 Ream Part 22a3 ... first joint portion 22a4 ... first end

Claims (10)

A first elastic plate having a first flat plate portion including a distal end portion, a connecting portion connected to the first flat plate portion, and a joint portion connected to the connecting portion;
A second elastic plate joined to the joint portion of the first elastic plate, and having a second flat plate portion facing the first flat plate portion of the first elastic plate;
A piezoelectric vibrating element provided on a surface on the second elastic plate side of the first flat plate portion of the first elastic plate;
A mass addition member attached to the tip end side of the first elastic plate;
Equipped with
The first elastic plate is configured to be able to generate sounds of a plurality of types of frequencies by the vibration of the bending mode,
The first elastic plate vibrates in the bending mode so that sound can be generated by the vibration in the bending mode at a frequency different from the frequency of the harmonic when the first flat plate portion vibrates in the bending mode. A vibrating device comprising a first flat plate portion and the connecting portion. The vibrating device according to claim 1, wherein the first flat plate portion and the connecting portion are configured such that sound can be generated also by vibrating only the first flat plate portion in a bending mode. . The vibration device according to claim 1 or 2, wherein the frequency different from the frequency of the harmonic when only the first flat plate part vibrates in the bending mode is a frequency other than the frequency of the multiple of the fundamental mode in the bending mode. . 4. The vibration of the first elastic plate generating sound according to any one of claims 1 to 3, wherein a node is located in a portion of the first elastic plate to which the mass addition member is attached. Vibration device. In the first elastic plate, the connection portion extends from the first flat plate portion toward the second elastic plate.
The joint portion extends from the connection portion in a direction away from the tip end, and the joint portion has a surface extending parallel to the second flat plate portion of the second elastic plate. The vibration device according to any one of claims 1 to 4, which is joined to the second elastic plate at the surface. The vibration device according to any one of claims 1 to 5, wherein the bending stiffness of the second elastic plate is higher than the bending stiffness of the first elastic plate. The thickness of the said 2nd flat plate part of the said 2nd elastic board is thinner than the thickness of the part by which the said 2nd elastic board is joined to the said 1st elastic board. The vibration device according to item 1. The vibration device according to any one of claims 1 to 7, further comprising a circuit unit for driving the piezoelectric vibration element. The vibration device according to claim 8, wherein the circuit unit is configured to change a frequency of an input signal input to the piezoelectric vibration element. An input signal is input from the outside to the piezoelectric vibration element of the vibration device according to any one of claims 1 to 8, and the frequency of the input signal is changed to vibrate the first elastic plate. A method of driving a vibrating device that simultaneously generates sounds of different heights.

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