JP6188567B2 - Sound generator - Google Patents

Description

  The present invention relates to a sound generator that vibrates a contact surface with which a sound generator contacts and generates sound from the contact surface.

  Conventional electronic devices such as mobile phones generate sound from speakers provided in the electronic devices. Dynamic speakers are the mainstream of speakers used in conventional electronic devices. For example, Patent Document 1 discloses a vibration generator having a dynamic speaker structure including a magnet, a voice coil, a diaphragm, and a case for housing them. An apparatus is described.

Japanese Utility Model Publication No. 5-85192

  However, since the vibration generating device described in Patent Document 1 has a dynamic speaker structure, an increase in the number of components is unavoidable and the weight increases. The output of the dynamic speaker depends on the size of the diaphragm for generating sound inside, and the output becomes smaller as the speaker is smaller. Therefore, an increase in the size of the apparatus is inevitable in order to obtain good sound characteristics.

  An object of the present invention made in view of such a viewpoint is to provide a sound generator that can be reduced in size and weight and can generate a good sound.

The sound generator according to the present invention that achieves the above object is as follows.
A piezoelectric vibration part having a piezoelectric element;
A weight for applying a load to the piezoelectric vibrating portion;
A control unit that controls an input voltage as a sound signal applied to the piezoelectric element based on a frequency characteristic;
In a state where a load from the weight is applied to the piezoelectric vibrating portion, the piezoelectric vibrating portion is deformed according to an input voltage applied to the piezoelectric element from the control unit, and the sound is generated by the deformation of the piezoelectric vibrating portion. to vibrate the placed surface generator is mounted by generating a sound from the mounting surface,
A measuring unit that contacts the mounting surface and measures the amplitude of vibration of the mounting surface;
The said control part controls the said input voltage based on the frequency characteristic with respect to the amplitude of the vibration of the said mounting surface .

  The control unit may control the input voltage to be a predetermined value.

In addition, the sound generator according to the present invention that achieves the above-described object,
A piezoelectric vibration part having a piezoelectric element;
A weight for applying a load to the piezoelectric vibrating portion;
A voltage measuring unit for measuring an output voltage from the piezoelectric element;
A control unit that controls an input voltage as a sound signal applied to the piezoelectric element based on a frequency characteristic based on the measured output voltage;
In a state where a load from the weight is applied to the piezoelectric vibrating portion, the piezoelectric vibrating portion is deformed according to an input voltage applied to the piezoelectric element from the control unit, and the sound is generated by the deformation of the piezoelectric vibrating portion. to vibrate the placed surface generator is mounted by generating a sound from the mounting surface,
The voltage measuring unit measures, as the output voltage, a voltage output from the piezoelectric vibrating unit based on a force received from the mounting surface as a reaction of the force applied to the mounting surface by the piezoelectric vibrating unit .

  The control unit may control the output voltage to be a predetermined value.

  The piezoelectric element is a multilayer piezoelectric element, and may be elastically deformed along the stacking direction.

The piezoelectric vibration unit may include a covering member that transmits vibration due to deformation of the piezoelectric element to the contact surface to vibrate the contact surface.
A support member provided on a side surface of the sound generator;
The measurement unit is provided on a side surface of the sound generator,
The support member and the measurement unit may support the sound generation unit on both sides of the piezoelectric vibration unit on the side surface of the sound generation unit.

  According to the present invention configured as described above, it is possible to provide a sound generator that can be reduced in size and weight and can generate good sound.

1 is an external perspective view showing a schematic configuration of a sound generator according to a first embodiment of the present invention. It is an external appearance perspective view of the principal part which decomposes | disassembles and shows the back surface side of the mobile telephone of FIG. It is a figure which shows the structure of the laminated piezoelectric element of FIG. It is a figure which shows the modification of a lamination type piezoelectric element. It is a partial expanded sectional view of the piezoelectric vibration part of FIG. It is a functional block diagram of the principal part of the mobile telephone of FIG. It is a figure which shows typically the frequency characteristic of the sound generated using a lamination type piezoelectric element. It is a flowchart which shows the control procedure of the input voltage which the control part of FIG. 6 performs. It is a figure which shows arrangement | positioning of the piezoelectric vibration part and elastic member in the sound generator of FIG. It is the schematic for demonstrating the operation | movement as a sound generator by the mobile telephone of FIG. It is a functional block diagram of the principal part of the sound generator which concerns on 2nd Embodiment. It is a figure which shows the example of the input voltage and output voltage of a lamination type piezoelectric element. It is a flowchart which shows the control procedure of the input voltage which the control part of the sound generator which concerns on 2nd Embodiment performs. It is a figure which shows the structure of the lamination type piezoelectric element of the sound generator which concerns on 2nd Embodiment. It is an external appearance perspective view which shows schematic structure of the sound generator in which a measurement part has a vibration detection part. It is a figure which shows typically the frequency characteristic of the amplitude of the vibration of a contact surface at the time of using a laminated type piezoelectric element. It is a figure which shows three modifications of the holding | maintenance form of a piezoelectric vibration part. It is a figure which shows schematic structure of the principal part which shows the modification of a piezoelectric vibration part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an external perspective view of the sound generator according to the first embodiment of the present invention. The sound generator according to the present embodiment includes a mobile phone 10 such as a smartphone, a piezoelectric vibration unit 60, and an elastic member 70. As will be described later, the mobile phone 10 functions as a weight (weight of a sound generator) that applies a load to the piezoelectric vibrating portion 60. The mobile phone 10 includes a housing 20 whose external shape is substantially rectangular. In the housing 20, the panel 30, the input unit 40, and the microphone 91 are arranged on the front side of the mobile phone 10, and as shown in FIG. The display unit 50 is held. In addition, a battery pack, a camera unit, and the like are mounted on the back side of the housing 20 and covered with the battery lid 21.

  The panel 30 includes a touch panel that detects contact, a cover panel that protects the display unit 50, and the like, and is formed of, for example, glass or a synthetic resin such as acrylic. The panel 30 has a rectangular shape, for example. The panel 30 may be a flat plate or a curved panel whose surface is smoothly inclined. When panel 30 is a touch panel, it detects contact of a user's finger, pen, stylus pen, or the like. As a detection method of the touch panel, any method such as a capacitance method, a resistance film method, a surface acoustic wave method (or an ultrasonic method), an infrared method, an electromagnetic induction method, and a load detection method can be used. In the present embodiment, for convenience of explanation, panel 30 is a touch panel.

  The input unit 40 receives an operation input from a user, and includes, for example, an operation button (operation key). The panel 30 can also accept an operation input from the user by detecting contact from the user.

  The display unit 50 is a display device such as a liquid crystal display, an organic EL display, or an inorganic EL display.

  The sound generator according to the present embodiment includes a piezoelectric vibration portion 60 for a sound generator and a sheet-like elastic member 70 on the side surface 20a of one long side of the casing 20 of the mobile phone 10. The elastic member 70 is made of, for example, rubber, silicone, polyurethane, or the like. When the mobile phone 10 is placed on a horizontal contact surface such as a desk with the side surface 20a facing downward, that is, when the mobile phone 10 is laid sideways, at least the piezoelectric vibrating portion 60 and the elastic member 70 are It is supported in contact with the contact surface. The arrangement of the piezoelectric vibrating portion 60 and the elastic member 70 will be described in detail later.

  The microphone 91 is used to detect a user's voice during a call and to detect a sound generated from a contact surface during sound generation by the piezoelectric vibration unit 60 to measure a frequency characteristic of sound pressure.

  FIG. 2 is a schematic perspective view of an essential part of the cellular phone 10 of FIG. On the back side of the housing 20, a battery pack 80, a camera unit 81, and the like are mounted. The mobile phone 10 according to the present embodiment includes a holding unit 100 that houses and holds the piezoelectric vibrating unit 60 on the back side of the housing 20. The holding | maintenance part 100 is extended along the transversal direction of the housing | casing 20, and has the slit 101 which has the uniform width | variety opened to the side surface 20a.

  The piezoelectric vibration unit 60 includes a piezoelectric element 61, an O-ring 62, and an insulating cap 63 that is a covering member. A piezoelectric element is an element that expands or contracts or bends according to an electromechanical coupling coefficient of a constituent material by applying an electric signal (voltage). These elements are made of, for example, ceramic or quartz. The piezoelectric element may be a unimorph, bimorph or multilayer piezoelectric element. The multilayer piezoelectric element includes a multilayer bimorph element in which bimorphs are laminated (for example, about 8 to 40 layers), a plurality of dielectric layers made of, for example, PZT (lead zirconate titanate), and the plurality of dielectric layers. There is a stack type composed of a laminated structure with electrode layers arranged between body layers. A unimorph expands and contracts when an electric signal is applied, a bimorph bends when an electric signal is applied, and a stack type stacked piezoelectric element expands and contracts along the stacking direction when an electric signal is applied.

  In the present embodiment, the piezoelectric element 61 is formed of a stack type stacked piezoelectric element. The laminated piezoelectric element 61 includes, for example, a dielectric 61a made of ceramics such as PZT and an internal electrode having a comb-like cross section, as shown in the enlarged cross-sectional view and plan view in FIGS. 61b are alternately stacked. The internal electrode 61b is formed by alternately laminating the electrode connected to the first side electrode 61c and the electrode connected to the second side electrode 61d, and electrically connects the first side electrode 61c or the second side electrode 61d, respectively. Connected to.

  The laminated piezoelectric element 61 shown in FIGS. 3A and 3B has, on one end face, a first lead connection portion 61e electrically connected to the first side surface electrode 61c and a second side surface electrode 61d. An electrically connected second lead connecting portion 61f is formed. A first lead wire 61g and a second lead wire 61h are connected to the first lead connecting portion 61e and the second lead connecting portion 61f, respectively. In addition, the first side electrode 61c, the second side electrode 61d, the first lead connection portion 61e, and the second lead connection portion 61f are connected to the first lead connection portion 61e and the second lead connection portion 61f, respectively. 61g and the second lead wire 61h are connected and covered with an insulating layer 61i.

  The stacked piezoelectric element 61 has a length in the stacking direction of, for example, 5 mm to 120 mm. Moreover, the cross-sectional shape in the direction orthogonal to the stacking direction of the multilayer piezoelectric element 61 can be, for example, a substantially square shape of 2 mm square to 10 mm square or an arbitrary shape other than the square shape. Note that the number of laminated piezoelectric elements 61 and the cross-sectional area of the laminated piezoelectric element 61 depend on the weight of the mobile phone 10 serving as a weight (for example, 80 g to 800 g in the case of a portable electronic device). It is determined as appropriate so that the sound pressure or sound quality of the sound generated from the contact surface can be sufficiently secured.

  As will be described later with reference to FIG. 6, the laminated piezoelectric element 61 is supplied with a sound signal (reproduced sound signal) from the control unit 130. In other words, a voltage corresponding to the sound signal is applied from the control unit 130 to the laminated piezoelectric element 61. When the voltage applied from the control unit 130 is an AC voltage, when a positive voltage is applied to the first side electrode 61c, a negative voltage is applied to the second side electrode 61d. Conversely, when a negative voltage is applied to the first side electrode 61c, a positive voltage is applied to the second side electrode 61d. When a voltage is applied to the first side electrode 61c and the second side electrode 61d, polarization occurs in the dielectric 61a, and the stacked piezoelectric element 61 expands and contracts from a state where no voltage is applied. The direction of expansion and contraction of the stacked piezoelectric element 61 is substantially along the stacking direction of the dielectric 61a and the internal electrode 61b. Alternatively, the expansion / contraction direction of the multilayer piezoelectric element 61 substantially coincides with the lamination direction of the dielectric 61a and the internal electrode 61b. Since the laminated piezoelectric element 61 expands and contracts substantially along the stacking direction, there is an advantage that the vibration transmission efficiency in the stretching direction is good.

  3A and 3B, the first side electrode 61c and the second side electrode 61d are alternately connected to the internal electrode 61b, and are connected to the first lead connection portion 61e and the second lead connection portion 61f. It can also be a through-hole connected to each other. 3 (a) and 3 (b), the first lead connecting portion 61e and the second lead connecting portion 61f are formed of a first side electrode 61c and a first side electrode 61c at one end of the multilayer piezoelectric element 61, as shown in FIG. You may form in the 2nd side electrode 61d.

  As shown in the partial enlarged cross-sectional view of FIG. 5, the laminated piezoelectric element 61 has one end side surface having the first lead connection portion 61 e and the second lead connection portion 61 f in the slit 101 of the holding portion 100 of the housing 20. It is fixed via an adhesive 102 (for example, epoxy resin). Further, a cap 63 is inserted into the other end portion of the multilayer piezoelectric element 61 and is fixed by the adhesive 102.

  The cap 63 is formed of a material that can reliably transmit the expansion and contraction vibration caused by the stacked piezoelectric element 61 to a contact surface such as a desk, for example, hard plastic. When it is desired to suppress damage to the contact surface 150, the cap 63 may be a relatively soft plastic instead of a hard plastic. The cap 63 is formed with an entry portion 63 a located in the slit 101 and a projection 63 b protruding from the housing 20 in a state of being attached to the multilayer piezoelectric element 61, and located in the slit 101. An O-ring 62 is disposed on the outer periphery of the entry portion 63a. The O-ring 62 is made of, for example, silicone rubber. The O-ring 62 is used to move and hold the multilayer piezoelectric element 61 and at the same time makes it difficult for moisture or dust to enter the slit 101. The protrusion 63b has a hemispherical tip. The tip of the protruding portion 63b is not limited to a hemispherical shape, but may be any shape as long as it is capable of reliably transmitting a point contact or a surface contact with a contact surface such as a desk and transmitting expansion and contraction vibration by the laminated piezoelectric element 61 It can be. In FIG. 5, the gap between the O-ring 62 and the adhesion portion of the multilayer piezoelectric element 61 to the slit 101 can be filled with gel or the like to further enhance the dustproof and waterproof effect. The piezoelectric vibrating portion 60 is attached to the holding portion 100, and the protruding portion 63 b of the cap 63 protrudes from the side surface 20 a of the housing 20 in a state where the battery lid 21 is attached to the housing 20. Further, the protruding portion 63 b of the cap 63 has a facing surface 63 c that is a surface facing the side surface 20 a of the housing 20. As shown in FIG. 5, the opposing surface 63c is separated from the side surface 20a by a length d in a state where no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand or contract.

  FIG. 6 is a functional block diagram of the main part of the mobile phone 10 according to the present embodiment. The mobile phone 10 includes a measurement unit 90, a wireless communication unit 110, a control unit 130, and a storage unit 140 in addition to the panel 30, the input unit 40, the display unit 50, and the multilayer piezoelectric element 61 described above. Panel 30, input unit 40, display unit 50, measurement unit 90, wireless communication unit 110, and storage unit 140 are connected to control unit 130. The laminated piezoelectric element 61 is connected to a digital signal processor (DSP) included in the control unit 130.

  The measuring unit 90 measures frequency characteristics when using the multilayer piezoelectric element 61 to generate sound from the contact surface. In the present embodiment, the measurement unit 90 includes a microphone 91 and measures the frequency characteristics of sound pressure generated from the contact surface based on the output of the microphone 91.

  The wireless communication unit 110 has a known configuration and is wirelessly connected to a communication network via a base station or the like. The storage unit 140 stores various types of information, for example, the frequency characteristics measured by the measurement unit 90. The control unit 130 is a processor that controls the overall operation of the mobile phone 10. The control unit 130 controls an input voltage as a reproduction sound signal (a voltage corresponding to a reproduction sound signal of a call partner's voice or a ringing melody or music, etc.) applied to the multilayer piezoelectric element 61. The reproduced sound signal may be based on music data stored in an internal memory, or music data stored in an external server or the like may be reproduced via a network.

  Here, the control performed by the control unit 130 will be specifically described. When sound is generated using the laminated piezoelectric element 61, it is preferable that sound is generated with a desired frequency characteristic. However, for example, even when a sound signal having the same voltage at each frequency is applied to the laminated piezoelectric element 61, the intensity of the generated sound is not uniform. More specifically, for example, in the case where the frequency of the sound signal applied to the multilayer piezoelectric element 61 matches the resonance frequency of the mobile phone 10 or the resonance frequency of the contact surface, FIG. ), A stronger sound is generated as compared with a case where a sound signal of another frequency is applied to the multilayer piezoelectric element 61. Thus, if the difference in the sound pressure intensity based on the frequency is large, it is inconvenient for the user. Therefore, the control unit 130 controls the input voltage based on the frequency characteristics so that the sound generated from the contact surface has the target frequency characteristics. The target frequency characteristic may be any frequency characteristic. For example, as shown schematically in FIG. 7B, the target frequency characteristic may have a uniform sound pressure at all frequencies. Further, the target frequency characteristic may be, for example, a sound pressure that is weaker as the frequency is higher, or a sound pressure in a predetermined frequency band is made stronger or weaker.

  In order to perform such control, the control unit 130 includes, for example, a digital signal processor (DSP) having an equalizer, an A / D conversion circuit, and the like, and a required signal such as equalizing processing or D / A conversion processing is applied to the digital signal. By performing the processing, an input voltage as an analog reproduction sound signal is generated and applied to the multilayer piezoelectric element 61. Note that the DSP may be provided in the mobile phone 10 independently of the control unit 130. In this case, the multilayer piezoelectric element 61 is connected to the control unit 130 via an independent DSP.

  FIG. 8 is a flowchart showing the input voltage control procedure performed by the control unit 130. The control unit 130 can control the input voltage for a frequency band in an arbitrary range, but in the description of the flowchart of FIG. 8, it is assumed that the input voltage is controlled for a frequency band in the range of 100 Hz to 20 kHz. To do.

  First, the control unit 130 initializes the frequency f and sets f = 100 Hz (step S101). Then, the pure tone signal having the set frequency f = 100 Hz is applied to the multilayer piezoelectric element 61 with the reference voltage Vr (step S102). Although the reference voltage Vr can be an arbitrary voltage, in the present embodiment, it is necessary that the voltage be at a level at which the microphone 91 can detect at least the sound generated from the contact surface by the application of the pure sound signal. .

  Next, the sound pressure of the sound generated from the contact surface due to the application of the pure sound signal is measured by the microphone 91, and the control unit 130 acquires the sound pressure measurement result from the microphone 91 (step S103). Then, the control unit 130 stores the acquired sound pressure measurement result in the storage unit 140 in association with the frequency f = 100 (step S104). In this way, the control unit 130 can acquire the sound pressure of the sound generated from the contact surface when the reference voltage Vr is applied to the multilayer piezoelectric element 61 when the frequency f = 100 Hz.

  Next, the control unit 130 increases the value of the frequency. In the present embodiment, the frequency is increased by 1 Hz by the calculation of f = f + 1 (step S105). And the control part 130 judges whether the value of the increased frequency f is larger than 20 kHz (step S106).

  When the frequency value is 20 kHz or less (No in Step S106), the control unit 130 applies the pure tone signal at the frequency f increased in Step S106 to the multilayer piezoelectric element 61 with the reference voltage Vr (Step S102). As a result, the sound pressure of the sound generated from the contact surface is acquired. The controller 130 thus repeats steps S102 to S106, thereby acquiring the relationship between the reference voltage Vr and the sound pressure of the sound generated from the contact surface at each frequency from 100 Hz to 20 kHz.

  And the control part 130 acquires a target frequency characteristic, when the value of the frequency f is larger than 20 kHz (Yes of step S106), ie, when the frequency characteristic from 100Hz to 20kHz is acquired (step S107). The target frequency characteristic may be stored in advance in the storage unit 140, for example, or may be set by the user using the input unit 40.

  And the control part 130 determines the input voltage to the lamination type piezoelectric element 61 based on a frequency characteristic with reference to the acquired target frequency characteristic (step S108). The input voltage is determined so that the sound generated from the contact surface has a predetermined target frequency characteristic. For example, when the sound pressure of the sound generated from the contact surface is stronger than the sound pressure of the target frequency characteristic because a certain frequency matches the resonance frequency of the contact surface, the control unit 130 determines according to the strength of the sound pressure. The input voltage is weakened so that the sound pressure of the sound generated from the contact surface is lowered to the sound pressure of the target frequency characteristic. On the other hand, when the sound pressure of the sound generated from the contact surface at a certain frequency is weaker than the sound pressure of the target frequency characteristic, the control unit 130 determines the sound generated from the contact surface according to the strength of the sound pressure. The input voltage is increased so that the sound pressure increases to the sound pressure of the target frequency characteristic. Then, the control unit 130 applies the determined input voltage to the multilayer piezoelectric element 61 (step S109). By such equalizing, the control unit 130 realizes the target frequency characteristic.

  In addition, in step S105 of the flowchart of FIG. 8, it has been described that the frequency value is increased by 1 Hz. However, the increase in the frequency f value is not limited to every 1 Hz, and can be increased arbitrarily. . Further, the increase in the value of the frequency f is not increased by a predetermined width, but may be swept from 100 Hz to 20 kHz, for example. In this case, the control unit 130 can acquire the frequency characteristics continuously from 100 Hz to 20 kHz. The control unit 130 can control the input signal applied to the multilayer piezoelectric element 61 by executing the flow shown in FIG. 8 before generating sound using the multilayer piezoelectric element 61. In addition, the control unit 130 executes the flow illustrated in FIG. 8 while generating sound using the multilayer piezoelectric element 61, and updates the acquired frequency characteristics stored in the storage unit 140. can do.

  Next, the arrangement of the piezoelectric vibrating portion 60 and the elastic member 70 will be described with reference to FIG. FIG. 9 shows a state where the mobile phone 10 is placed on a horizontal contact surface 150 such as a desk with the side surface 20a facing downward. Here, the desk is an example of the contacted member of the present invention, and the contact surface 150 is an example of the contact surface with which the sound generator contacts. As shown in FIG. 9, the mobile phone 10 is supported with at least the piezoelectric vibrating portion 60 and the elastic member 70 in contact with the contact surface 150. A point G is the center of gravity of the mobile phone 10. That is, point G is the center of gravity of the sound generator weight.

  In FIG. 9, the elastic member 70 has a lowermost end 701. The lowermost end 701 is a portion of the elastic member 70 that comes into contact with the contact surface 150 when the mobile phone 10 is placed on a horizontal contact surface 150 such as a desk with the side surface 20a facing downward.

  The piezoelectric vibration part 60 has a lowermost end part 601. The lowermost end portion 601 is a portion of the piezoelectric vibrating portion 60 that contacts the contact surface 150 when the mobile phone 10 is placed on a horizontal contact surface 150 such as a desk with the side surface 20a facing downward. The lowermost end 601 is, for example, the tip of the cap 63.

  The mobile phone 10 has a lowermost end portion 101. It is assumed that the lowermost end portion 101 of the mobile phone 10 does not include the piezoelectric vibrating portion 60 when the mobile phone 10 is placed on the horizontal contact surface 150 such as a desk with the side surface 20a facing downward. In this case, the contact surface 150 is in contact with the contact surface 150. The lowermost end 101 of the mobile phone 10 is, for example, a corner of the housing 20, but is not limited thereto. When the side surface 20 a is provided with a protruding portion that protrudes from the side surface 20 a, the protruding portion may be the lowermost end portion 101 of the mobile phone 10. The protrusion is, for example, a side key or a connector cap.

  In FIG. 9, a dotted line L is a line that passes through the center of gravity G of the mobile phone 10 and is perpendicular to the contact surface 150 when the mobile phone 10 is placed on a horizontal contact surface 150 such as a desk with the side surface 20 a facing down. (Virtual line). The alternate long and short dash line I is a line (virtual line) that connects the lowermost end 701 of the elastic member 70 and the lowermost end 101 of the mobile phone 10 when it is assumed that the piezoelectric vibrating portion 60 does not exist.

  In FIG. 9, a region R <b> 1 is a region on one side delimited by the dotted line L in the mobile phone 10. The region R2 is a region on the other side delimited by the dotted line L in the mobile phone 10. The elastic member 70 is provided on the side of the region R1 on the side surface 20a. In addition, the piezoelectric vibrating portion 60 is provided on the side of the region R2 on the side surface 20a.

  The piezoelectric vibrating portion 60 is preferably provided at a position as close as possible to the dotted line L on the region R2 side of the side surface 20a. As a result, the load applied to the piezoelectric vibrating portion 60 becomes larger than when the piezoelectric vibrating portion 60 is provided at a position separated from the dotted line L on the region R2 side of the side surface 20a. Thereby, the mobile phone 10 can be effectively used as the weight of the sound generator.

  The elastic member 70 is preferably provided at a position as far as possible from the dotted line L on the region R1 side of the side surface 20a. As a result, even when the piezoelectric vibrating portion 60 is provided as close as possible to the dotted line L, a sufficient distance between the elastic member 70 and the piezoelectric vibrating portion 60 is ensured, and the sound generator is stably placed on the contact surface 150. Can be placed.

  The lowest end portion 601 of the piezoelectric vibrating portion 60 is a one-dot chain line I when a voltage is not applied to the laminated piezoelectric element 61 and the laminated piezoelectric element 61 extends most from a state where it does not expand or contract or when the laminated piezoelectric element 61 has a maximum amplitude. It is better to be located closer to the contact surface 150 side. That is, the lowermost end portion 601 is in contact with the multi-layered piezoelectric element 61 more than the one-dot chain line I when the multi-layered piezoelectric element 61 is extended to the maximum from the state where it does not expand or contract or when the multi-layered piezoelectric element 61 has the maximum amplitude. It is good to protrude to the surface 150 side. Thereby, the contact surface 150 can be appropriately vibrated by the piezoelectric vibrating portion 60.

  The lowermost end 601 of the piezoelectric vibration unit 60 is applied when the laminated piezoelectric element 61 is contracted most from the state in which no voltage is applied to the laminated piezoelectric element 61 and the laminated piezoelectric element 61 does not expand or contract, or the laminated piezoelectric element 61. When the minimum amplitude is, it is preferable to be located closer to the contact surface 150 than the alternate long and short dash line I. That is, the lowest end portion 601 is one point at the time when the multilayer piezoelectric element 61 is at the minimum amplitude when the multilayer piezoelectric element 61 is contracted the most from the state where the multilayer piezoelectric element 61 is not expanded and contracted. It is preferable that the contact surface 150 protrudes from the chain line I. Thereby, the lowermost end portion 101 of the mobile phone 10 is less likely to come into contact with the contact surface 150. For example, depending on the type of coating of the housing 20, the coating is less likely to be peeled off. Further, abnormal noise is less likely to occur between the lowermost end portion 101 and the contact surface 150.

  Note that the mobile phone 10 may be placed on a contact surface such as a desk with a commercially available stand or the like attached to the housing 20 with the side surface 20a facing downward. In this case, the side surface 20a of the mobile phone 10 is supported at two points by the piezoelectric vibrating portion 60 and the elastic member 70, and further supported by a stand.

  FIGS. 10A, 10B, and 10C are schematic diagrams for explaining the operation of the mobile phone 10 according to the present embodiment as a sound generator. When the mobile phone 10 is caused to function as a sound generator, the mobile phone 10 has a cap 63 and an elastic member 70 of the piezoelectric vibrating portion 60 with the side surface 20a side of the housing 20 facing downward, as shown in FIG. Is placed sideways so as to come into contact with the contact surface 150 such as a desk. Thereby, the weight of the mobile phone 10 is given to the piezoelectric vibrating portion 60 as a load. That is, the mobile phone 10 functions as a weight of the sound generator according to the present invention. In the state shown in FIG. 10A, the stacked piezoelectric element 61 does not expand and contract because no voltage is applied.

  In this state, when the multilayer piezoelectric element 61 of the piezoelectric vibration unit 60 is driven by the reproduction sound signal, the multilayer piezoelectric element 61 is brought into contact with the elastic member 70 as shown in FIGS. 10B and 10C. With the contact portion with the surface 150 as a fulcrum, the cap 63 expands and contracts according to the reproduced sound signal without being separated from the contact surface 150. If there is no inconvenience such as the occurrence of abnormal noise due to the lower end 101 contacting the contact surface 150, the lower end 101 may be somewhat separated. The difference between the length of the laminated piezoelectric element 61 when it is most expanded and the length when it is most contracted is, for example, 0.05 μm to 50 μm. As a result, the expansion and contraction vibration of the multilayer piezoelectric element 61 is transmitted to the contact surface 150 through the cap 63 and the contact surface 150 vibrates, and the contact surface 150 functions as a vibration speaker to generate sound from the contact surface 150. Note that if the difference between the length when it is most stretched and the length when it is most contracted is less than 0.05 μm, the contact surface 150 may not be vibrated properly, whereas if it exceeds 50 μm, the vibration is large. There is a risk that the sound generator will rattle.

  Here, as described above, when it is assumed that the piezoelectric vibrating portion 60 does not exist when the multilayer piezoelectric element 61 is extended to the end of the cap 63, the cap 63 and the lowermost end 701 of the elastic member 70 are portable. It is good to be located on the contact surface 150 side with respect to the line (one-dot chain line I in FIG. 9) connecting the lowermost end portion 101 of the telephone 10. The tip of the cap 63 is preferably located closer to the contact surface 150 than the virtual line when the multilayer piezoelectric element 61 is contracted most.

  Further, the distance d between the side surface 20a and the facing surface 63c of the cap 63 shown in FIG. 5 is a state where the voltage is not applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 is contracted most from the state where the multilayer piezoelectric element 61 does not expand and contract. It is better to be longer than the amount of displacement when Thereby, even when the laminated piezoelectric element 61 is in the most contracted state (the state shown in FIG. 10C), the side surface 20a of the housing 20 and the cap 63 can be hardly contacted. Therefore, it is difficult for the cap 63 to fall off the multilayer piezoelectric element 61.

  The arrangement location on the side surface 20a of the piezoelectric vibrating section 60, the length of the stacked piezoelectric element 61 in the stacking direction, the size of the cap 63, and the like are appropriately determined so as to satisfy the above-described conditions.

  According to the sound generator according to the present embodiment, since the laminated piezoelectric element is used as a vibration source, the number of parts can be reduced and the number of parts can be reduced as compared with a conventional vibration generator having a dynamic speaker structure. It can be configured simply and can be reduced in size and weight. Further, as the stacked piezoelectric element, the stack type stacked piezoelectric element 61 is used to cause expansion / contraction vibration along the stacking direction by the reproduced sound signal and to transmit the expansion / contraction vibration to the contact surface. The vibration transmission efficiency in the deformation direction is good, and the contact surface can be vibrated efficiently. In addition, since the multilayer piezoelectric element 61 is brought into contact with the contact surface via the cap 63, the multilayer piezoelectric element 61 can be prevented from being damaged. Further, when the mobile phone 10 is placed sideways and the cap 63 of the piezoelectric vibration unit 60 is brought into contact with the contact surface, the weight of the mobile phone 10 is applied to the cap 63 as a load. Thus, the expansion and contraction vibration of the piezoelectric vibration unit 60 can be efficiently transmitted to the contact surface.

  In addition, according to the sound generator according to the present embodiment, when the multilayer piezoelectric element 61 is used to generate sound, a reference voltage Vr in a predetermined frequency range is applied to the multilayer piezoelectric element 61 in advance to obtain frequency characteristics. And the input voltage applied to the laminated piezoelectric element 61 is controlled based on the acquired frequency characteristic. Therefore, the mobile phone 10 can generate a sound having a desired target frequency characteristic. In addition, since the input voltage can be controlled according to the property of the contact surface, the mobile phone 10 can generate a good sound regardless of the property of the contact surface. Further, when the mobile phone 10 is reduced in weight, depending on the sound frequency, the mobile phone 10 may be separated from the contact surface due to the reaction of the vibration of the multilayer piezoelectric element 61, and abnormal noise may occur. In the sound generator according to the embodiment, since the input voltage is controlled based on the frequency characteristics, the input voltage at such a frequency can be kept low, and abnormal noise can be prevented. For this reason, the mobile phone 10 can be reduced in weight.

  In addition, since the sound generator according to the present embodiment can mainly transmit the vibration of the multilayer piezoelectric element directly to the contact surface, the conventional technology for transmitting the vibration of the multilayer piezoelectric element to another elastic body is possible. In contrast, when generating sound, it does not depend on the limit frequency on the high frequency side where other elastic bodies can vibrate. The limit frequency on the high frequency side where the other elastic body can vibrate is the reciprocal of the shortest time from the time when the other elastic body is deformed by the laminated piezoelectric element until it returns to the deformable state. Become. In consideration of this, the weight of the sound generator according to the present embodiment may have rigidity (bending strength) that does not cause bending deformation due to deformation of the multilayer piezoelectric element.

(Second Embodiment)
In 1st Embodiment, the control part 130 demonstrated the case where the input voltage was controlled based on the frequency characteristic of the sound pressure which the microphone 91 acquired. In the second embodiment, a case where the control unit 130 controls the input voltage based on the output voltage of the stacked piezoelectric element measured by the voltage measurement unit will be described. The schematic configuration of the mobile phone according to the second embodiment is the same as that of the mobile phone according to the first embodiment shown in FIGS. In the second embodiment, the sound generator may not include the microphone 91. Hereinafter, description of the same points as in the first embodiment will be omitted, and different points will be described.

  FIG. 11 is a functional block diagram of the main part of the sound generator according to the second embodiment. Unlike the mobile phone according to the first embodiment, the mobile phone 10 according to the present embodiment includes a voltage measurement unit 120. The voltage measurement unit 120 is connected to the stacked piezoelectric element 61 and the control unit 130. The voltage measurement unit 120 measures the output voltage from the multilayer piezoelectric element 61 and transmits it to the control unit 130.

  Here, the measurement of the output voltage performed by the voltage measurement unit 120 will be described. When an input voltage as a sound signal is applied, the laminated piezoelectric element 61 performs stretching vibration by converting the input voltage into a force. On the other hand, when a force is applied, the stacked piezoelectric element 61 converts the force into a voltage. Output voltage. When the multilayer piezoelectric element 61 is applied to the mobile phone 10 and an input voltage is applied to the multilayer piezoelectric element 61, the multilayer piezoelectric element 61 applies a force to the contact surface by performing stretching vibration. At this time, the multilayer piezoelectric element 61 receives a force from the contact surface and outputs a voltage as a reaction of the force applied to the contact surface. Since this output voltage changes according to the force received by the multilayer piezoelectric element 61, the state of vibration on the contact surface can be detected by measuring the output voltage in the voltage measuring unit 120. For example, assume that a voltage as shown in FIG. 12A is input to the multilayer piezoelectric element 61. At this time, the multilayer piezoelectric element 61 outputs a voltage as shown in FIG. 12B, for example, due to the vibration of the contact surface affected by the property of the contact surface such as the resonance frequency. Therefore, in the sound generator according to the present embodiment, the characteristics of the output voltage with respect to the input voltage are measured for each frequency, and the voltage of the frequency applied to the multilayer piezoelectric element 61 is controlled based on the measurement result. Therefore, it is possible to generate a good sound.

  FIG. 13 is a flowchart showing a control procedure of the input voltage performed by the control unit 130 of the sound generator according to the present embodiment. The control unit 130 can control the input voltage for a frequency band in an arbitrary range, but in the description of the flowchart of FIG. 13, it is assumed that the input voltage is controlled for a frequency band in the range of 100 Hz to 20 kHz. To do.

  When starting the flow, the control unit 130 first acquires the target frequency characteristic Vf (f = 100 Hz to 20 kHz) (step S201). The target frequency characteristic Vf may be stored in advance in the storage unit 140, for example, or may be set by the user using the input unit 40. Then, the control unit 130 initializes the frequency f and sets f = 100 Hz (step S202). Further, the control unit 130 initializes the adjustment coefficient Kf for determining the value of the input voltage with respect to the target frequency characteristic (step S203). The initialization of the adjustment coefficient Kf can be set to an arbitrary value, for example, the adjustment coefficient Kf = 1.

Next, the control unit 130 calculates the input voltage _{Vf in} (step S204). The input voltage Vf _in is calculated by the product of the adjustment coefficient Kf and the target frequency characteristic Vf. Thus, for example, if you set the adjustment coefficient Kf = 1 in step S203, first, the value of the target frequency characteristic Vf is input voltage _{Vf in.} Then, the control unit 130 applies the calculated input voltage _{Vf in} the laminated piezoelectric element 61 (step S205). Upon application of the input voltage Vf _in the laminated piezoelectric element 61, the laminated piezoelectric element 61 is driven to vibrate the contact surface, at the same time, the laminated piezoelectric element 61 outputs a voltage by receiving a force from the contact surface. Then, the voltage measuring unit 120 measures the output voltage Vf _out , and the control unit 130 acquires the measured output voltage Vf _out (step S206).

Next, the control unit 130 confirms whether or not the acquired output voltage Vf _out is within a predetermined range with respect to the target frequency characteristic Vf. In this flow, as an example, the control unit 130 confirms whether or not the output voltage Vf _out is within a range of ± α (α is a predetermined constant) with respect to the target frequency characteristic Vf. . That is, the control unit 130 determines whether or not the value of the output voltage Vf _out is smaller than the value of Vf + α (step S207). When the value of the output voltage Vf _out is equal to or greater than the value of Vf + α (No in Step S207), the control unit 130 decreases the value of the adjustment coefficient Kf. The reduction width of the adjustment coefficient Kf can be an arbitrary width, for example, 0.01 as shown in FIG. In this case, the control unit 130 decreases the adjustment coefficient Kf by the calculation of Kf = Kf−0.01 (step S214). Then, the control unit 130, by calculating the product of the adjustment coefficient Kf and the target frequency characteristic which is newly calculated, to calculate the input voltage _{Vf in} (step S204).

On the other hand, when the value of the output voltage Vf _out is smaller than the value of Vf + α (Yes in step S207), the control unit 130 subsequently determines whether or not the value of the output voltage Vf _out is larger than the value of Vf−α. (Step S208). When the value of the output voltage Vf _out is equal to or less than the value of Vf−α (No in Step S208), the control unit 130 increases the value of the adjustment coefficient Kf. Here, as in step S214, the adjustment coefficient Kf can be increased by an arbitrary width, for example, by 0.01. That is, in the flowchart shown in FIG. 13, the control unit 13 increases the adjustment coefficient Kf by the calculation of Kf = Kf + 0.01 (step S214). Then, the control unit 130, by calculating the product of the adjustment coefficient Kf and the target frequency characteristic which is newly calculated, to calculate the input voltage _{Vf in} (step S204). In this manner, the control unit 130 obtains Vf _out that is within a predetermined range with respect to the target frequency characteristic Vf by repeating Step S204 to Step S208.

When the value of the output voltage Vf _out is larger than Vf−α (Yes in step S208), the control unit 130 stores the value of the adjustment coefficient Kf used to output the value of the output voltage Vf _{out in} the storage unit 140. Store (step S209). Subsequently, the control unit 130 increases the value of the frequency. In the present embodiment, the frequency is increased by 1 Hz by the calculation of f = f + 1 (step S210). And the control part 130 judges whether the value of the increased frequency f is larger than 20 kHz (step S211).

When the frequency value is 20 kHz or less (No in step S211), the control unit 130 initializes the adjustment coefficient Kf in order to obtain the adjustment coefficient Kf at the frequency f value increased in step S210 (step S203). . Then, by repeating steps S203 to S211, an adjustment coefficient Kf for outputting Vf _out within a predetermined range with respect to the target frequency characteristic Vf at each frequency from 100 Hz to 20 kHz is obtained, and stored in the storage unit 140. Store.

When the value of the frequency f is larger than 20 kHz (Yes in step S211), that is, when the adjustment coefficient Kf at each frequency from 100 Hz to 20 kHz is stored in the storage unit 140, the control unit 130 stores the adjustment coefficient Kf in the storage unit. based on the adjustment coefficients Kf, to determine the input voltage _{Vf in} for outputting the target frequency characteristic Vf at each frequency (step S212). Then, the control unit 130 applies the input voltage _{Vf in} determining the laminated piezoelectric element 61 (step S213). By such equalizing, the control unit 130 realizes the target frequency characteristic.

  Note that in step S210 in the flowchart of FIG. 13, the frequency value is described as being increased by 1 Hz. However, the increase in the frequency f value is not limited to every 1 Hz, and can be an arbitrary increase range. . Further, the increase in the value of the frequency f is not increased by a predetermined width, but may be swept from 100 Hz to 20 kHz, for example. In this case, the control unit 130 can acquire the frequency characteristics continuously from 100 Hz to 20 kHz. The control unit 130 can control the input signal applied to the multilayer piezoelectric element 61 by executing the flow described in FIG. 13 before generating sound using the multilayer piezoelectric element 61. Further, the control unit 130 executes the flow illustrated in FIG. 13 while the sound is generated using the multilayer piezoelectric element 61, and updates the value of the adjustment coefficient Kf stored in the storage unit 140. be able to.

  In the present embodiment, the multilayer piezoelectric element 61 is driven by applying an input voltage from the control unit 130 and outputs an output voltage by receiving a force from the contact surface. As shown in FIG. 14, a driving unit that drives and a detection unit that outputs an output voltage may be provided. In the multilayer piezoelectric element 61 shown in FIG. 14, the drive unit side has the same configuration as that described in FIG. On the other hand, the multilayer piezoelectric element 61 includes a third side electrode 61j and a fourth side electrode 61k on the detection unit side. The third side electrode 61j is disposed on the same side surface as the first side electrode 61c of the multilayer piezoelectric element 61, and the fourth side electrode 61k is the side surface of the multilayer piezoelectric element 61 on the same side as the second side electrode 61d. Is arranged. As the internal electrode 61b on the detection unit side, the electrode connected to the third side electrode 61j and the electrode connected to the fourth side electrode 61k are alternately stacked, and the third side electrode 61j or the fourth side electrode are respectively stacked. 61k is electrically connected. Also, a third lead connection portion 61l and a fourth lead connection portion 61m are formed so as to contact the third side surface electrode 61j and the fourth side surface electrode 61k, respectively, and the third lead connection portion 61l and the fourth lead connection portion are formed. The third lead wire 61n and the fourth lead wire 61o are connected to the part 61m, respectively. The third lead wire 61n and the fourth lead wire 61o are connected to the voltage measurement unit 120 and transmit the output voltage of the multilayer piezoelectric element 61 to the voltage measurement unit 120.

  The present invention is not limited to the first and second embodiments described above, and various modifications or changes can be made. For example, the mobile phone 10 according to the first embodiment includes one elastic member 70, but the mobile phone 10 may include a plurality of elastic members 70 on the side surface 20a. Thereby, the mobile phone 10 can be more stably placed on the contact surface.

  Moreover, in the said 1st Embodiment, although the measurement part 90 had the microphone 91 and was demonstrated as measuring the frequency characteristic of the sound which the microphone 91 acquires, the aspect of the measurement part 90 is not restricted to this. For example, the measurement unit 90 may include a vibration detection unit, and may measure frequency characteristics of the amplitude of vibration of the contact surface detected by the vibration detection unit. As shown in the external perspective view of FIG. 15, the mobile phone 10 includes, on the side surface 20a, a vibration detection unit 92 such as a vibration pickup having a piezoelectric element, an acceleration sensor, or the like. When the mobile phone 10 is placed horizontally on the contact surface, the vibration detection unit 92 contacts the contact surface and measures the amplitude of vibration on the contact surface.

  When sound is generated using the laminated piezoelectric element 61, it is preferable that sound is generated with a desired frequency characteristic. However, for example, even when a sound signal having the same voltage at each frequency is applied to the laminated piezoelectric element 61, the vibration amplitude of the contact surface may not be uniform. More specifically, for example, when the frequency of the sound signal applied to the multilayer piezoelectric element 61 matches the resonance frequency of the contact surface, as shown schematically in FIG. The amplitude of the vibration of the contact surface is increased as compared with the case where a frequency sound signal is applied to the multilayer piezoelectric element 61. Since the intensity of the sound generated from the contact surface has a correlation with the amplitude of the vibration of the contact surface, as shown in FIG. 16A, the sound is generated from the contact surface when the difference in amplitude based on the frequency is large. The intensity of the sound is not uniform, and the desired frequency characteristics of the sound cannot be obtained. This is inconvenient for the user. Therefore, the control unit 130 controls the input voltage based on the frequency characteristic so that the contact surface vibrates with an amplitude such that the sound generated from the contact surface has the target frequency characteristic. For example, as shown in FIG. 16B, the control unit 130 can vibrate the contact surface with the same amplitude at all frequencies by controlling the input voltage. In addition, the amplitude of the contact surface by control of the control part 130 is not restricted to what is shown in FIG.16 (b), It can be made arbitrary.

  When the measurement unit 90 includes the vibration detection unit 92, in the flowchart of FIG. 8, after the control unit 130 applies the reference voltage Vr in step S102, the vibration amplitude of the contact surface is measured by the vibration detection unit 92. The control unit 130 acquires the measurement result of the amplitude from the vibration detection unit 92 (step S103). Then, the control unit 130 stores the acquired amplitude measurement result in the storage unit 140 in association with the frequency f at which the amplitude is measured (step S104). In subsequent step S108, control unit 130 refers to the amplitude stored in storage unit 140 and determines the input voltage based on the frequency characteristics. In addition, when the measurement part 90 has the vibration detection part 92, the other detailed step of the flowchart of FIG. 8 is the same as 1st Embodiment.

  Further, the structure for fixing the piezoelectric vibrating portion 60 to the holding portion 100 is not limited to that shown in FIG. For example, as shown in FIGS. 17A to 17C, the piezoelectric vibration unit 60 may be held by the holding unit 100. The holding unit 100 shown in FIG. 17A includes a wide slit 101a that opens to the side surface 20a, and a narrow slit 101b that continues to the slit 101a. The laminated piezoelectric element 61 has one end portion arranged in the narrow slit 101 b and the side surface fixed to the slit 101 b via the adhesive 102. Further, the wide slit 101 a is filled with a filler 103 such as silicone rubber or gel that does not hinder the expansion and contraction operation of the multilayer piezoelectric element 61 in the gap with the multilayer piezoelectric element 61. If the piezoelectric vibrating portion 60 is held by the holding portion 100 in this manner, the cellular phone 10 can be waterproofed more reliably without using a waterproof packing such as an O-ring. In addition, by covering the portion protruding from the side surface 20a of the multilayer piezoelectric element 61 with an insulating cap, the multilayer piezoelectric element 61 can be reliably insulated.

  The holding unit 100 shown in FIG. 17B includes a tapered slit 101c that expands toward the side surface 20a, and a narrow slit 101d that continues to the tapered slit 101c. The laminated piezoelectric element 61 has one end portion disposed in the narrow slit 101 d and the side surface fixed to the slit 101 d via the adhesive 102. The tapered slit 101 c is filled with a filler 103 such as silicone rubber or gel that does not hinder the expansion and contraction operation of the multilayer piezoelectric element 61 in the gap with the multilayer piezoelectric element 61. With this configuration, the same effect as that of the holding unit 100 in FIG. 17A can be obtained, and since the tapered slit 101c is provided, the multilayer piezoelectric element 61 can be easily assembled to the holding unit 100. There are advantages that can be made.

  The holding unit 100 shown in FIG. 17C has a slit 101 having a uniform width as in the above embodiment, but the laminated piezoelectric element 61 has an end face on one end side via an adhesive 102. It is fixed to the slit 101. Further, an O-ring 62 is disposed at an appropriate position of the multilayer piezoelectric element 61 in the slit 101. Such a holding mode of the laminated piezoelectric element 61 is particularly suitable when the laminated piezoelectric element 61 has a lead wire connecting portion formed on a side electrode as shown in FIG. Etc. are advantageous.

  Further, in the above embodiment and the modified examples of FIGS. 17A to 17C, the piezoelectric vibrating portion 60 omits the cap 63, and the tip surface of the multilayer piezoelectric element 61 is formed directly or made of an insulating member or the like. You may mount in a contact surface via a vibration transmission member. In addition, the piezoelectric element in the first embodiment is not limited to the stack type stacked piezoelectric element described above, and a unimorph, bimorph, or stacked bimorph element may be used. FIG. 18 is a diagram showing a schematic configuration of a main part when a bimorph is used. The bimorph 65 has a long rectangular shape, one surface 65 a is exposed on the side surface 20 a of the housing 20, and both long ends are held by the holding unit 100. The holding unit 100 has an opening 101e that holds the bimorph 65, and the inner surface of the opening 101e on the back surface 65b side of the bimorph 65 is curved. According to this configuration, when the housing 20 is placed on the contact surface so that the bimorph 65 contacts the contact surface and the bimorph 65 is driven by the reproduction sound signal, the bimorph 65 bends (curves) and vibrates. As a result, the vibration of the bimorph 65 is transmitted to the contact surface, and the contact surface functions as a vibration speaker, and a reproduction sound is generated from the contact surface. Note that a coating layer such as polyurethane may be formed on the surface 65 a of the bimorph 65.

  In the above-described embodiment, the example in which the piezoelectric vibrating portion 60 is disposed on the side surface 20a of the housing 20 and protrudes from the side surface 20a has been described. However, the present invention is not limited to this. Depending on the dimensions of the housing 20 and the dimensions of the piezoelectric vibration part 60, the piezoelectric vibration part 60 may protrude from the battery lid 21, for example.

  Moreover, although said to-be-contacted member was a desk and said contact surface was a horizontal mounting surface of a desk in said embodiment, this invention is not limited to this. The contact surface need not be a horizontal surface. For example, the contact surface may be a surface perpendicular to the desk ground. Examples of the contacted member having a surface perpendicular to the ground include a partition for dividing a space.

  Moreover, in the said embodiment, although the sound generator was mounted in the mobile telephone 10 and the mobile telephone 10 was functioned as a weight, a weight is not restricted to this. For example, various electronic devices such as portable music players, stationary televisions, telephone conference systems, laptop computers, projectors, wall clocks / wall televisions, alarm clocks, photo frames, etc. can be used as weights to generate sound. A vessel can also be installed.

DESCRIPTION OF SYMBOLS 10 Mobile phone 20 Case 20a Side surface 21 Battery lid 30 Panel 40 Input part 50 Display part 60 Piezoelectric vibration part 61 Piezoelectric element 62 O-ring 63 Cap 70 Elastic member 80 Battery pack 81 Camera unit 90 Measurement part 91 Microphone 92 Vibration detection part 100 Holding unit 101 Slit 110 Wireless communication unit 120 Voltage measurement unit 130 Control unit 140 Storage unit 150 Contact surface

Claims (7)

A piezoelectric vibration part having a piezoelectric element;
A weight for applying a load to the piezoelectric vibrating portion;
A control unit that controls an input voltage as a sound signal applied to the piezoelectric element based on a frequency characteristic;
In a state where a load from the weight is applied to the piezoelectric vibrating portion, the piezoelectric vibrating portion is deformed according to an input voltage applied to the piezoelectric element from the control unit, and the sound is generated by the deformation of the piezoelectric vibrating portion. to vibrate the placed surface generator is mounted by generating a sound from the mounting surface,
A measuring unit that contacts the mounting surface and measures the amplitude of vibration of the mounting surface;
The said control part is a sound generator which controls the said input voltage based on the frequency characteristic with respect to the amplitude of the vibration of the said mounting surface .   The sound generator according to claim 1, wherein the control unit controls the input voltage to be a predetermined value. A piezoelectric vibration part having a piezoelectric element;
A weight for applying a load to the piezoelectric vibrating portion;
A voltage measuring unit for measuring an output voltage from the piezoelectric element;
A control unit that controls an input voltage as a sound signal applied to the piezoelectric element based on a frequency characteristic based on the measured output voltage;
In a state where a load from the weight is applied to the piezoelectric vibrating portion, the piezoelectric vibrating portion is deformed according to an input voltage applied to the piezoelectric element from the control unit, and the sound is generated by the deformation of the piezoelectric vibrating portion. to vibrate the placed surface generator is mounted by generating a sound from the mounting surface,
The voltage measuring unit measures , as the output voltage, a voltage output from the piezoelectric vibrating unit based on a force received from the mounting surface as a reaction of a force applied to the mounting surface by the piezoelectric vibrating unit .
Sound generator. The sound generator according to claim 3 , wherein the control unit controls the output voltage to be a predetermined value. The sound generator according to any one of claims 1 to 4 , wherein the piezoelectric element is a stacked piezoelectric element, and expands and contracts along a stacking direction. The sound generation according to any one of claims 1 to 5 , wherein the piezoelectric vibration unit includes a covering member that transmits vibration due to deformation of the piezoelectric element to the contact surface to vibrate the contact surface. vessel. A support member provided on a side surface of the sound generator;
The measurement unit is provided on a side surface of the sound generator,
The support member and the measurement unit support the sound generation unit on both sides of the piezoelectric vibration unit on the side surface of the sound generation unit.
The sound generator according to any one of claims 1 to 6.

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