JP6188568B2 - 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 electronic devices. For example, Patent Document 1 describes a vibration generating device having a dynamic speaker structure including a magnet, a voice coil, a diaphragm, and a case for housing them.

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, and the smaller the speaker, the smaller the output. 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 which 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 housing,
A piezoelectric vibration part that includes a piezoelectric element and is capable of selectively transitioning between a first state in which at least a part protrudes from the housing and a second state in which the piezoelectric element does not protrude;
A weight for applying a load to the piezoelectric vibrating portion;
A locking mechanism for selectively maintaining the piezoelectric vibrating portion in the first state and the second state ;
When the piezoelectric element is driven in response to a sound signal in a state where a load from the weight is applied to the piezoelectric vibrating part when the piezoelectric vibrating part is in the first state, The piezoelectric vibration portion is deformed to vibrate the contact surface that the piezoelectric vibration portion is in contact with to generate sound from the contact surface ;
The lock mechanism releases the first state when a force greater than a predetermined load is applied to the piezoelectric vibration part protruding from the housing when the piezoelectric vibration part is in the first state. It said piezoelectric vibrating unit Ru is displaced toward the second state Te, those.

The piezoelectric element is
Driven when the piezoelectric vibration part is in the first state;
It is good that it is not driven when the piezoelectric vibration part is in the second state.

A state detection unit that detects the first state or the second state of the piezoelectric vibration unit;
The driving of the piezoelectric element may be controlled based on the output of the state detection unit.

  The piezoelectric element is a stacked piezoelectric element, and is preferably stretched and 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.

  According to the present invention, 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 of a sound generator according to a first embodiment of the present invention. It is a schematic 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. FIG. 3 is a partial enlarged cross-sectional view illustrating a first state and a second state of the piezoelectric vibration unit in FIG. 1. It is a functional block diagram of the principal part of the mobile telephone of FIG. It is a functional block diagram which shows the structure of an example of the piezoelectric element drive part of FIG. It is a figure which shows an example of the frequency characteristic of LPF of FIG. 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 an external appearance perspective view of the sound generator which concerns on 2nd Embodiment of this invention. It is a figure which shows arrangement | positioning of the piezoelectric vibration part and elastic member in the sound generator of FIG. It is a figure which shows the modification of the sound generator which concerns on this invention.

  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 case 20, the panel 30 and the input unit 40 are disposed on the front side of the mobile phone 10, and as shown in FIG. 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 a synthetic resin such as glass or 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 the panel 30 is a touch panel, the touch of a user's finger, pen, stylus pen, or the like is detected. As a detection method of the touch panel, an arbitrary 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, or 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 a user's contact with a soft key or the like displayed on the display unit 50.

  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. As will be described later, the piezoelectric vibrating portion 60 is provided so as to partially protrude from the side surface 20a. The elastic member 70 is made of, for example, rubber, silicone, polyurethane, or the like. When the cellular phone 10 is placed on a horizontal placement surface such as a desk with the side surface 20a facing downward with the piezoelectric vibration part 60 partially protruding from the side surface 20a, that is, the cellular phone 10 is turned sideways. When stood, it is supported at two points on the mounting surface by the piezoelectric vibrating portion 60 and the elastic member 70. The arrangement of the piezoelectric vibrating portion 60 and the elastic member 70 will be described in detail later.

  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 90, and the like are mounted. The mobile phone 10 includes a holding unit 100 that slidably holds the piezoelectric vibrating unit 60 on the back side of the housing 20. The holding unit 100 includes a slit 101 formed by a pair of guide members 105 and 106 that are spaced apart in the longitudinal direction of the housing 20 and extend along the short direction. One end of the slit 101 opens in the housing 20 and the other end opens in the side surface 20a. The guide members 105 and 106 forming the slit 101 are configured to be displaceable in the longitudinal direction of the housing 20 with respect to the side surface 20a. In addition, the end portions of the guide members 105 and 106 positioned on the inner side of the housing 20 have trapezoidal shapes that form a lock mechanism in cooperation with a holder 64 (to be described later) of the piezoelectric vibrating portion 60 on the opposing surface sides. The protrusions 105a and 106a are formed.

  The piezoelectric vibration unit 60 includes a piezoelectric element 61, an O-ring 62, an insulating cap 63 that is a covering member, and a holder 64. The piezoelectric element 61 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 61 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 via the piezoelectric element driving unit 120. In other words, a voltage corresponding to the sound signal is applied to the multilayer piezoelectric element 61 from the control unit 130 via the piezoelectric element driving unit 120. 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.

  The piezoelectric vibrating part 60 extends in the slit 101 and is slidably arranged as shown in the partial enlarged cross-sectional views in FIGS. The laminated piezoelectric element 61 has one end side having the first lead connecting portion 61 e and the second lead connecting portion 61 f shown in FIG. 3 inserted into the holder 64 and fixed by the adhesive 102. A cap 63 is inserted on the other end surface side of the multilayer piezoelectric element 61 and is fixed by the adhesive 102.

  The holder 64 is formed of, for example, hard plastic or the like and selectively engages with the protrusions 105a and 106a of the guide members 105 and 106 at the upper end in FIGS. 5A and 5B to constitute a lock mechanism. An upper end engaging portion 64a and a recessed portion 64b are provided. As shown in FIG. 5A, the lock mechanism is configured so that one of the piezoelectric vibrating parts 60 is in a state where the protrusions 105 a and 106 a of the guide members 105 and 106 are engaged with the upper end engaging part 64 a of the holder 64. The cap 63 which is a part holds the first state protruding from the side surface 20 a of the housing 20. Further, as shown in FIG. 5 (b), the lock mechanism is configured such that the cap 63 is attached to the housing 20 when the protrusions 105 a and 106 a of the guide members 105 and 106 are engaged with the recess 64 b of the holder 64. It does not protrude from the side surface 20 a, that is, the second state in which the entire piezoelectric vibrating portion 60 is accommodated in the housing 20 is maintained.

  The cap 63 is formed of a material that can reliably transmit the expansion and contraction vibration caused by the laminated piezoelectric element 61 to a mounting surface (contact surface) such as a desk, such as a hard plastic. When it is desired to suppress the mounting surface from being damaged, the cap 63 may not be a hard plastic but may be a relatively soft plastic. The cap 63 has an entry portion 63a that always faces the wall surface of the side surface 20a that forms the slit 101, and a contact portion 63b that contacts a placement surface such as a desk in the first state of the piezoelectric vibration portion 60. An O-ring 62 is disposed on the outer periphery of the portion 63a. The O-ring 62 is made of, for example, silicone rubber. The O-ring 62 is used to move and hold the piezoelectric vibrating portion 60 and at the same time, makes it difficult for moisture or dust to enter the slit 101. The contact portion 63b has a hemispherical tip. The tip of the contact portion 63b is not limited to a hemispherical shape, but has a shape capable of transmitting expansion and contraction vibration by the stacked piezoelectric element 61 by reliably making point contact or surface contact with a mounting surface (contact surface) such as a desk. Any shape can be used.

  As shown in FIG. 2, the holder 64 has a guide pin 65 on the surface on the battery lid 21 side so that the piezoelectric vibration portion 60 can be slid to selectively shift between the first state and the second state. Is provided. In addition, a guide hole 21 a through which the guide pin 65 passes is formed in the battery lid 21 so as to extend in the sliding direction of the piezoelectric vibrating portion 60, that is, in the short side direction of the housing 20. A slide plate 66 is attached to the guide pin 65 protruding from the guide hole 21a. As a result, the user slides the slide plate 66 in the short side direction of the housing 20 (the direction indicated by the double-headed arrow), whereby the piezoelectric vibrating portion 60 is shown in the first state shown in FIG. It is possible to selectively shift to the second state shown in 5 (b).

  The guide hole 21a is preferably subjected to dustproofing and waterproofing so that the guide pin 65 and the slide plate 66 can slide. Further, the lock mechanism is in a state where the piezoelectric vibrating portion 60 is in the first state, the mobile phone 10 is laid sideways, and the cap 63 of the piezoelectric vibrating portion 60 is in contact with a mounting surface such as a desk. Even when the multilayer piezoelectric element 61 is displaced by a sound signal in a state where the load w1 of the mobile phone 10 serving as a weight is received via the piezoelectric vibration unit 60, the first state of the piezoelectric vibration unit 60 is effectively maintained. Configured to be able to. When a predetermined load w2 or greater than the load w1 is applied to the cap 63 in the first state, the first state of the piezoelectric vibration unit 60 is released and the piezoelectric vibration unit 60 is directed to the second state. Configured to displace.

  Here, the predetermined load w2 is appropriately set according to the load w1 of the mobile phone 10 serving as a weight, the strength of the multilayer piezoelectric element 61 constituting the piezoelectric vibration unit 60, the load received by the displacement of the multilayer piezoelectric element 61, and the like. Is done. In the case of the mobile phone 10, since the weight is, for example, 80 g to 800 g (0.78 N to 7.8 N), the predetermined load w2 can be set to 0.94 N to 9.4 N, for example. Thereby, when the piezoelectric vibrating part 60 is in the first state, a predetermined load w2 or more in the stacking direction, that is, the longitudinal direction of the stacked piezoelectric element 61 through the cap 63 due to an impact such as dropping of the mobile phone 10. When the load is applied, the lock of the first state of the piezoelectric vibrating portion 60 is released, and the piezoelectric vibrating portion 60 is displaced from the first state in the direction of retracting into the housing 20.

  In addition, as shown in FIG. 2, a state detection unit for detecting the first state or the second state of the piezoelectric vibration unit 60 in conjunction with the slide operation of the piezoelectric vibration unit 60 is provided in the housing 20. 67 is provided. The state detection unit 67 can be configured using, for example, a tact switch or a photoelectric sensor. In addition, the state detection unit 67 includes, for example, a fixed contact provided on a part of one of the guide members 105 and 106, and a first state or a second state of the piezoelectric vibration unit 60 on a part of the holder 64 of the piezoelectric vibration unit 60. In this state, a movable contact that contacts or separates from the fixed contact may be provided. In FIG. 2, a tact switch that is ON / OFF controlled by the holder 64 of the piezoelectric vibration unit 60 in conjunction with the sliding operation of the piezoelectric vibration unit 60 is illustrated as the state detection unit 67.

  The state detection unit 67 is turned on or off when the piezoelectric vibration unit 60 is in the first state, and is turned off or on when the piezoelectric vibration unit 60 is in the second state. The multilayer piezoelectric element 61 is allowed to be driven according to the sound signal in a state where the state detection unit 67 detects the first state of the piezoelectric vibration unit 60, for example, and the state detection unit 67 is allowed to move to the piezoelectric vibration unit 60. It is controlled not to be driven in a state where the first state is not detected.

  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 wireless communication unit 110, a piezoelectric element driving unit 120, and a control unit 130 in addition to the panel 30, the input unit 40, the display unit 50, the stacked piezoelectric element 61, and the state detection unit 67 described above. Panel 30, input unit 40, display unit 50, state detection unit 67 and wireless communication unit 110 are connected to control unit 130. The stacked piezoelectric element 61 is connected to the control unit 130 via the piezoelectric element driving unit 120.

  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 control unit 130 is a processor that controls the overall operation of the mobile phone 10. In the state where the state detection unit 67 is detecting the first state of the piezoelectric vibration unit 60, the control unit 130 sends a reproduction sound signal (voice or voice of the other party) to the stacked piezoelectric element 61 via the piezoelectric element driving unit 120. A voltage corresponding to a reproduction sound signal of a ringing melody or music including music is applied. 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.

  The piezoelectric element driving unit 120 includes a signal processing circuit 121, a booster circuit 122, and a low-pass filter (LPF) 123, for example, as shown in FIG. The signal processing circuit 121 is configured by, for example, a digital signal processor (DSP) having an equalizer, an A / D conversion circuit, and the like, and the digital signal from the control circuit 130 is required for equalization processing, D / A conversion processing, and the like. The analog playback sound signal is generated and output to the booster circuit 122. Note that the function of the signal processing circuit 121 may be incorporated in the control circuit 130.

  The booster circuit 122 boosts the voltage of the input analog reproduction sound signal and applies it to the multilayer piezoelectric element 61 via the LPF 123. Here, the maximum voltage of the reproduced sound signal applied to the stacked piezoelectric element 61 by the booster circuit 122 can be set to, for example, 10 Vpp to 50 Vpp, but is not limited to this range, and the weight of the mobile phone 10 or the stacked piezoelectric It can be appropriately adjusted according to the performance of the element 61. Note that the reproduced sound signal applied to the multilayer piezoelectric element 61 may be biased with a DC voltage, or a maximum voltage may be set around the bias voltage.

  In addition to the multilayer piezoelectric element 61, the piezoelectric element generally has higher power loss at higher frequencies. Therefore, the LPF 123 has a frequency characteristic that attenuates or cuts at least part of a frequency component of about 10 kHz to 50 kHz or more, or gradually. Alternatively, it is set to have a frequency characteristic in which the attenuation rate increases stepwise. FIG. 8 shows, as an example, the frequency characteristics of the LPF 123 when the cutoff frequency is about 20 kHz. Thus, power consumption can be suppressed by attenuating or cutting high frequency components.

  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 in which the mobile phone 10 is placed on a horizontal placement surface 150 such as a desk with the side surface 20a facing downward in the first state of the piezoelectric vibrating section 60. Here, the desk is an example of a contacted member, and the placement surface 150 is an example of a contact surface (placement surface) with which the sound generator contacts. As shown in FIG. 9, the mobile phone 10 is supported on the mounting surface 150 at two points by the piezoelectric vibrating portion 60 and the elastic member 70. 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 portion 701 is a portion of the elastic member 70 that comes into contact with the placement surface 150 when the mobile phone 10 is placed on a horizontal placement 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 comes into contact with the placement surface 150 when the mobile phone 10 is placed on a horizontal placement surface 150 such as a desk with the side surface 20a down. . The lowermost end 601 is, for example, the tip of the cap 63.

  The mobile phone 10 has a lowermost end portion 101. The lowermost end 101 is configured such that when the mobile phone 10 of the mobile phone 10 is placed on a horizontal placement surface 150 such as a desk with the side surface 20 a facing down, the piezoelectric vibrating portion 60 is removed from the housing 20. This is a portion that comes into contact with the mounting surface 150 in the second state where it does not protrude. 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.

  9, the dotted line L passes through the center of gravity G of the mobile phone 10 and is perpendicular to the placement surface 150 when the mobile phone 10 is placed on the horizontal placement surface 150 such as a desk with the side surface 20a facing downward. A straight line (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 the piezoelectric vibrating portion 60 is in the second state.

  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. Thus, 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. It can be mounted on.

  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 positioned closer to the mounting surface 150 side. That is, the lowermost end portion 601 is placed more than the alternate long and short dash line I when no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 extends most from a state where it does not expand or contract or when the multilayer piezoelectric element 61 has the maximum amplitude. It is good to protrude to the mounting surface 150 side. Thereby, the mounting 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. It is good to be located in the mounting surface 150 side rather than the dashed-dotted line I at the time of the minimum amplitude. 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 contracts the most from the state in which the voltage is not applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand and contract. It is good to protrude from the chain line I to the mounting surface 150 side. Thereby, the lowermost end portion 101 of the mobile phone 10 is less likely to come into contact with the placement 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 placement surface 150.

  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 to function as a sound generator, the mobile phone 10 has the piezoelectric vibrating portion 60 in the first state and the side surface 20a side of the housing 20 downward as shown in FIG. The cap 63 and the elastic member 70 of the piezoelectric vibration unit 60 are placed sideways so as to be in contact with a placement surface (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 acts as a weight of the sound generator according to the present embodiment. 10A shows a state where no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand or contract.

  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 loaded with the elastic member 70 as shown in FIGS. The cap 63 does not move away from the placement surface (contact surface) 150 with the contact portion with the placement surface (contact surface) 150 as a fulcrum, and expands and contracts according to the reproduced sound signal. Note that the cap 63 may be slightly separated from the mounting surface (contact surface) 150 if there is no inconvenience such as abnormal noise generated when the lower end portion 101 contacts the mounting surface 150. 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 mounting surface 150 through the cap 63 to vibrate the mounting surface 150, and the mounting surface 150 functions as a vibration speaker and generates sound from the mounting surface 150. To do. In addition, if the difference between the length when stretched most and the length when shrunk most is less than 0.05 μm, there is a possibility that the mounting surface cannot be vibrated properly. There is a risk that the sound generator will rattle.

  Here, as described above, the distal end portion of the cap 63 is the same as the lowermost end portion 701 of the elastic member 70 when the piezoelectric vibrating portion 60 is in the first state when the stacked piezoelectric element 61 is extended most. It is better to be located on the placement surface 150 side than the line (the one-dot chain line I in FIG. 9) connecting the lowest end portion 101 of the mobile phone 10. The tip of the cap 63 may be positioned closer to the placement surface 150 than the virtual line when the multilayer piezoelectric element 61 is contracted most.

  The arrangement location on the side surface 20a of the piezoelectric element portion 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 conditions.

  According to the sound generator according to the present embodiment, since a piezoelectric element is used as a vibration source, the number of parts can be reduced compared with a conventional vibration generator having a dynamic speaker structure, and the number of parts can be reduced. And can be reduced in size and weight. In addition, the piezoelectric vibration unit 60 can selectively transition between a first state in which a part protrudes from the housing 20 and a second state in which the piezoelectric vibration unit 60 does not protrude, and responds to a sound signal when in the first state. Since driving is permitted and driving is rejected when not in the first state, the usability can be improved, and the cellular phone 10 when the piezoelectric vibrator 60 is not used (when it is in the second state). There is no loss of design.

  In addition, a stack-type multilayer piezoelectric element 61 is used as the piezoelectric element, and in the first state of the piezoelectric vibrator 60, the reproducing sound signal causes stretching vibration along the stacking direction, and the stretching vibration is transmitted to the contact surface 150. Therefore, the multilayer piezoelectric element 61 has good vibration transmission efficiency in the expansion / contraction direction (deformation direction) with respect to the contact surface 150, and the contact surface 150 can be vibrated efficiently. Further, in the first state of the piezoelectric vibrator 60, when the cellular phone 10 is placed sideways and the cap 63 of the piezoelectric vibrating unit 60 is brought into contact with the contact surface 150, the weight of the cellular phone 10 is applied to the cap 63 as a load. Therefore, the cap 63 can be reliably brought into contact with the contact surface 150, and the expansion / contraction vibration of the piezoelectric vibrating portion 60 can be efficiently transmitted to the contact surface 150. Therefore, a good sound can be generated.

  Further, the protrusions 105 a and 106 a of the guide members 105 and 106 and the upper end engaging portion 64 a and the concave portion 64 b formed on the holder 64 of the piezoelectric vibrating portion 60 constitute a locking mechanism of the piezoelectric vibrating portion 60. Then, with the protrusions 105a and 106a engaged with the upper end engagement part 64a, the piezoelectric vibration part 60 is held in the first state, and with the protrusions 105a and 106a engaged with the recess 64b, The unit 60 is held in the second state. The lock mechanism is configured such that the load received through the piezoelectric vibrating unit 60 in the first state of the piezoelectric vibrating unit 60 is the piezoelectric vibrating unit under a load received in a normal use state including the load w1 of the mobile phone 10 serving as a weight. 60 is effectively held in the first state. In addition, when the piezoelectric vibrating portion 60 receives a load greater than or equal to a predetermined load w2 greater than the load w1 in the first state, the lock mechanism releases the first state and puts the piezoelectric vibrating portion 60 into the second state. Displace toward. Accordingly, in the first state of the piezoelectric vibration unit 60, when an undesired load of a predetermined load w2 or more is applied via the piezoelectric vibration unit 60 due to an impact such as a drop of the mobile phone 10, the piezoelectric vibration unit 60 is It will be retracted into the body 20. Thereby, damage to the multilayer piezoelectric element 61 due to application of an undesired load to the piezoelectric vibrating portion 60 is effectively prevented. Moreover, since the multilayer piezoelectric element 61 is in contact with the contact surface 150 via the cap 63 even when used in the first state, damage to the multilayer piezoelectric element 61 during use can be prevented. Therefore, the piezoelectric vibration part 60 can be used stably over a long period of time.

  In addition, the sound generator according to the present embodiment can mainly transmit the vibration of the multilayer piezoelectric element 61 directly to the contact surface (mounting surface) 150. Unlike the case where the sound is transmitted to the elastic body, the sound does not depend on the limit frequency on the high frequency side where other elastic bodies can vibrate when generating sound. The limit frequency on the high frequency side where the other elastic body can vibrate is the reciprocal of the shortest of the times from when the other elastic body is deformed by the piezoelectric element until it returns to the deformable state.

(Second Embodiment)
FIG. 11 is an external perspective view of a sound generator according to the second embodiment of the present invention. The sound generator according to the present embodiment is the opposite side of the mobile phone 10 described in the first embodiment from the end provided with the elastic member 70 on the side surface 20a of the housing 20 via the piezoelectric vibrating portion 60. Further, an elastic member 71 is further provided at the end portion. Hereinafter, description of the same points as in the first embodiment will be omitted, and different points will be described.

  The elastic member 71 has a sheet shape like the elastic member 70. Similar to the elastic member 70, the elastic member 71 is made of, for example, rubber, silicone, polyurethane, or the like.

  Next, the arrangement of the piezoelectric vibrating portion 60, the elastic member 70, and the elastic member 71 will be described with reference to FIG. FIG. 12 shows a state in which the mobile phone 10 is placed on a horizontal placement surface 150 such as a desk with the side surface 20a facing downward in the first state of the piezoelectric vibration unit 60, as in FIG. Show. As shown in FIG. 12, the mobile phone 10 is supported on the placement surface 150 at three points by the piezoelectric vibrating portion 60, the elastic member 70, and the elastic member 71. 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. 12, a dotted line L passes through the center of gravity G of the mobile phone 10 when the mobile phone 10 is placed on a horizontal placement surface 150 such as a desk with the side surface 20a facing downward, as in FIG. This is a line (virtual line) perpendicular to the placement surface 150. The dotted line L1 is a line (imaginary line) that passes through the elastic member 70 and is perpendicular to the placement surface. A dotted line L2 is a line (imaginary line) that passes through the elastic member 71 and is perpendicular to the placement surface. The dotted line L1 is separated from the dotted line L by a length D1 in the horizontal direction. The dotted line L2 is separated from the dotted line L by a length D2 in the horizontal direction.

  In FIG. 12, a region R <b> 1 is a region on one side delimited by a 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. The elastic member 70 is disposed on the side surface 20a so as to be separated from the piezoelectric vibrating portion 60 by a length D1 in the horizontal direction. The elastic member 71 is provided on the side of the region R2 on the side surface 20a. The elastic member 71 is disposed on the side surface 20a so as to be spaced apart from the piezoelectric vibrating portion 60 by a length D2 in the horizontal direction.

  The piezoelectric vibrating portion 60 is provided on the dotted line L on the side surface 20a. That is, the piezoelectric vibration unit 60 passes through the center of gravity G of the mobile phone 10 and is perpendicular to the mounting surface 150 when the mobile phone 10 is mounted on a horizontal mounting surface 150 such as a desk with the side surface 20a facing down. Placed on a straight line. Thereby, the weight of the mobile phone 10 as a weight can be given to the piezoelectric vibrating portion 60 as a load, and the expansion and contraction vibration of the piezoelectric vibrating portion 60 can be efficiently transmitted to the placement surface (contact surface) 150. When D1 = D2, that is, when the elastic member 70 and the elastic member 71 are provided at symmetrical positions in the horizontal direction with the piezoelectric vibration part 60 interposed therebetween, the sound generator is stably mounted on the mounting surface 150. can do.

  When the multilayer piezoelectric element 61 is driven by a reproduction sound signal, the piezoelectric vibration unit 60 vibrates and expands according to the reproduction sound signal without the cap 63 being separated from the placement surface (contact surface) 150. Note that the elastic members 70 and 71 may be slightly separated from each other if there is no inconvenience such as the lower end portions of the elastic member 70 and the elastic member 71 coming into contact with the mounting surface 150 to generate abnormal noise.

  When the mobile phone 10 is placed on a horizontal placement surface 150 such as a desk with the side surface 20a facing downward, the elastic member 70 and the elastic member 71 are elastically given the weight of the mobile phone 10 as a load. Deform. That is, the elastic member 70 and the elastic member 71 contract in a direction perpendicular to the placement surface 150 due to the weight of the mobile phone 10. The amount of elastic deformation of the elastic member 70 and the elastic member 71 in a state in which no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand or contract is from the state in which the voltage is not applied to the multilayer piezoelectric element 61 and does not expand or contract. It is good that it is larger than the amount of displacement when stretched most. Thus, the elastic member 70 and the elastic member 71 are unlikely to be separated from the placement surface 150 when the multilayer piezoelectric element 61 is extended to the maximum, and the sound generator is stably placed on the placement surface 150. Also in this embodiment, the same effect as the first embodiment can be obtained.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, the mobile phone 10 may be mounted on a mounting 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. Alternatively, as shown in FIG. 13, a stand 22 may be rotatably provided on the battery lid 21. In this case, the stand 22 is coupled to the holder 64 of the piezoelectric vibration unit 60 via a known connection mechanism that converts, for example, rotation into linear movement inside the housing 20, and in conjunction with the rotation of the stand 22, The piezoelectric vibration unit 60 may be held in the first state or the second state. That is, as shown in FIG. 13, when the stand 22 is opened with respect to the battery lid 21 and the cellular phone 10 is placed on the placement surface 150, the cap 63 is placed on the placement surface with the piezoelectric vibrating portion 60 in the first state. When the stand 22 is closed with respect to the battery lid 21, the piezoelectric vibrating portion 60 is set in the second state. If comprised in this way, usability can be improved more.

  Further, the piezoelectric vibrating portion 60 may omit the cap 63, and in the first state, the tip surface of the multilayer piezoelectric element 61 may be brought into contact with the contact surface directly or via a vibration transmitting member made of an insulating member or the like. . In addition, the piezoelectric element is not limited to the stack type stacked piezoelectric element described above, and a unimorph, bimorph, or stacked bimorph element may be used. When using a unimorph or a bimorph, the entire piezoelectric element may protrude from the housing 20 in the first state.

  Further, in FIG. 7, an LPF having the same characteristics as the LPF 123 may be provided between the signal processing circuit 121 and the booster circuit 122. In FIG. 7, the LPF 123 may be omitted by providing the equalizer of the signal processing circuit 121 with the function of the LPF 123.

  In the above embodiment, an example in which the piezoelectric vibrating portion 60 protrudes from the side surface 20a of the housing 20 has been described, but 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. The contact surface may be a surface perpendicular to the desk ground, for example. 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. The weight is not limited to an electronic device, and may be a vase, a chair, or the like. Furthermore, the present invention is not limited to a sound generator, and may be configured as a piezoelectric vibration portion for a sound generator having a piezoelectric element, or a sound generator and a contacted member having a contact surface with which the sound generator contacts. It can also be configured as a sound generation system provided with these, and it should be understood that these are also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Cellular phone 20 Case 20a Side surface 21 Battery lid 21a Guide hole 22 Stand 30 Panel 40 Input part 50 Display part 60 Piezoelectric vibration part 61 Multilayer piezoelectric element (piezoelectric element)
62 O-ring 63 Cap 64 Holder 64a Upper end engaging portion 64b Recessed portion 65 Guide pin 66 Slide plate 67 State detecting portion 70 Elastic member 71 Elastic member 100 Holding portion 101 Slit 102 Adhesive 105, 106 Guide member 105a, 106a Protruding portion 150 Mounted Placement surface (contact surface)

Claims (5)

A housing,
A piezoelectric vibration part that includes a piezoelectric element and is capable of selectively transitioning between a first state in which at least a part protrudes from the housing and a second state in which the piezoelectric element does not protrude;
A weight for applying a load to the piezoelectric vibrating portion;
A locking mechanism for selectively maintaining the piezoelectric vibrating portion in the first state and the second state ;
When the piezoelectric element is driven in response to a sound signal in a state where a load from the weight is applied to the piezoelectric vibrating part when the piezoelectric vibrating part is in the first state, The piezoelectric vibration portion is deformed to vibrate the contact surface that the piezoelectric vibration portion is in contact with to generate sound from the contact surface ;
The lock mechanism releases the first state when a force greater than a predetermined load is applied to the piezoelectric vibration part protruding from the housing when the piezoelectric vibration part is in the first state. It said piezoelectric vibrating unit Ru is displaced toward the second state Te,
Sound generator. The piezoelectric element is
Driven when the piezoelectric vibration part is in the first state;
Not driven when the piezoelectric vibration part is in the second state;
The sound generator according to claim 1. A state detection unit that detects the first state or the second state of the piezoelectric vibration unit;
The driving of the piezoelectric element is controlled based on the output of the state detector.
The sound generator according to claim 1 or 2 . The piezoelectric element is a laminated piezoelectric element, and expands and contracts along the lamination direction.
The sound generator according to any one of claims 1 to 3 . 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.
The sound generator according to any one of claims 1 to 4 .

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