JP6329613B2 - 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.

An image display device according to the present invention that achieves the above object is as follows.
A housing,
A piezoelectric vibrating portion having a piezoelectric element disposed in the housing;
A vibration unit capable of taking a non-contact state that does not contact the piezoelectric vibration unit and a contact state that contacts the piezoelectric vibration unit;
A weight for applying a load to the excitation part via the piezoelectric vibration part,
In the contact state, in a state where a load from the weight is applied to the excitation unit, the piezoelectric vibration unit is deformed according to a sound signal, and the excitation unit is contacted by deformation of the piezoelectric vibration unit The surface is vibrated to generate sound from the contact surface.
In the contact state, the vibration unit may be in contact with the piezoelectric vibration unit on a side closer to the contact surface than the piezoelectric vibration unit.
The vibration unit may be capable of taking the non-contact state and the contact state by sliding and displacing in a direction along the surface of the housing.
The contact surface may be a mounting surface on which the sound generator is mounted.

A cover portion having the excitation portion and displaceable in the housing;
The cover part may be configured to place the excitation part in the contact state at a first position, to place the excitation part in the non-contact state at a second position, and to protect the piezoelectric vibration part. .

  The piezoelectric element may be driven in a state where the cover portion is in the first position, and may not be driven in a state where the cover portion is in the second position.

  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 excitation unit to vibrate the excitation unit.

  The excitation unit may include a covering member that transmits vibration due to the piezoelectric vibration unit to the contact surface to vibrate the contact surface.

  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 an 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. FIG. 3 is a partial enlarged cross-sectional view of a contact state between a piezoelectric vibrating portion and a vibrating portion in FIG. 2. It is a schematic diagram which shows the 1st position and 2nd position of the cover part of FIG. 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 a vibration part, a projection part, and an 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 figure which shows three modifications of the holding | maintenance form of a piezoelectric vibration part. It is an external appearance perspective view which shows schematic structure of a sound generator provided with a circular-shaped cover part. It is a schematic diagram which shows the 1st position and 2nd position of a cover part of FIG. It is a figure which shows schematic structure of the principal part which shows the modification of a cover part.

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

  FIG. 1 is an external perspective view of a sound generator according to an embodiment of the present invention. The sound generator according to the present embodiment includes a mobile phone 10 such as a smartphone, an elastic member 70, and a cover 90. 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, 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 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 has a sheet-like elastic member 70 and a piezoelectric vibrating portion 60 inside the casing 20 (see FIG. 2) on the side surface 20a of one long side of the casing 20 of the mobile phone 10. ) Is provided. The elastic member 70 is made of, for example, rubber, silicone, polyurethane, or the like. The cover part 90 includes a vibration part 91 and a protrusion 92. The cover part 90 is provided in the housing | casing 20 so that a displacement is possible. The user of the mobile phone 10 can move the cover portion 90 by operating the projection 92 with his / her finger and displace it so as to slide in the longitudinal direction on the side surface 20a as indicated by an arrow 910. 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, the mobile phone 10 is contacted by the elastic member 70 and the vibration exciter 91. Supported at two points on the surface. The arrangement of the elastic member 70 and the excitation unit 91 will be described 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 81, and the like are mounted. In addition, a piezoelectric vibrating portion 60 having a piezoelectric element 61 is disposed in the housing 20. The mobile phone 10 has a recess 200 on the back side of the housing 20 that serves as a space for the excitation unit 91 to be displaced. The recess 200 has a surface 20b parallel to the side surface 20a. In addition, the mobile phone 10 includes a holding unit 100 that houses and holds the piezoelectric vibrating unit 60 on the back side of the housing 20. The holding unit 100 includes a slit 101 that extends along the short direction of the housing 20 and has a uniform width that opens toward the surface 20b. In addition, the mobile phone 10 includes a holding unit 900 and a holding unit 901 that store and hold both ends of the cover unit 90 on the back side of the housing 20. In FIG. 2, a part of the cover part 90 is stored and held in the holding part 901.

  As will be described later with reference to FIG. 6, when the cover 90 is displaced, the excitation unit 91 can take a contact state in contact with the piezoelectric vibration unit 60 and a non-contact state in which it does not contact. In the contact state, when the mobile phone 10 is placed on a horizontal contact surface such as a desk with the side surface 20a down, a weight (sound generation) applies a load to the excitation unit 91 via the piezoelectric vibration unit 60. Acts as a weight).

  The piezoelectric vibration unit 60 includes a piezoelectric element 61, an O-ring 62, and a covering member 63 that protects the piezoelectric element 61. 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 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. 7, 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 surface electrode 61c and the second side surface 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, respectively. It can also be a through hole. 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). A covering member 63 is inserted into the other end portion of the multilayer piezoelectric element 61 and fixed by the adhesive 102.

  The covering member 63 is formed of a material that can reliably transmit the expansion and contraction vibration due to the laminated piezoelectric element 61 to the excitation unit 91, for example, hard plastic. The covering member 63 is formed with an entry portion 63 a positioned in the slit 101 and a protruding portion 63 b protruding from the housing 20 in a state of being attached to the multilayer piezoelectric element 61. An O-ring 62 is disposed on the outer periphery of the entering 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. Further, the protruding portion 63b has a flat end at the tip. Note that the tip of the protrusion 63b is not limited to a planar shape, and can be any shape as long as it is capable of reliably transmitting point contact or surface contact to the excitation unit 91 and transmitting expansion and contraction vibration by the laminated piezoelectric element 61. can do. 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 part 60 is attached to the holding part 100, and the protruding part 63b of the covering member 63 protrudes from the surface 20b. Further, the tip of the protruding portion 63b of the covering member 63 is separated from the surface 20b by a length d in a state in which no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand and contract.

  The excitation unit 91 is formed of a material that can reliably transmit the expansion and contraction vibration caused by the laminated piezoelectric element 61 to a contact surface such as a desk, such as metal, ceramic, or hard plastic. The excitation unit 91 is held from both ends by a cover unit 90 having flexibility so as not to hinder the transmission of vibration of the multilayer piezoelectric element 61. The excitation unit 91 includes a cap 94 that is a covering member on the side surface 20 a side of the housing 20. The cap 94 is fixed by the adhesive 102. The cap 94 is formed of a material that can reliably transmit the expansion and contraction vibration due to the laminated piezoelectric element 61 transmitted through the excitation unit 91 to a contact surface such as a desk, such as a hard plastic. When it is desired to suppress damage to the contact surface, the cap 94 may be a relatively soft plastic instead of a hard plastic. Note that the cover 90 does not need to have flexibility as long as it does not hinder the transmission of vibration of the multilayer piezoelectric element 61 to the excitation unit 91, and the same material as that of the excitation unit 91 may be used. Good. In that case, the cover part 90 and the vibration part 91 may be integrally molded.

  FIG. 6A shows a contact state between the piezoelectric vibrating portion 60 and the vibrating portion 91, and at this time, the cover portion 90 is in the first position. FIG. 6B shows a non-contact state between the piezoelectric vibrating portion 60 and the vibrating portion 91. At this time, the cover portion 90 is in the second position. The user of the mobile phone 10 operates the protrusion 92 to displace the cover 90 (vibration unit 91), and switches between the first position and the second position, so A contact state and a non-contact state with the vibration part 91 can be switched. The first position in FIG. 6A is used when sound is generated from the mobile phone 10. That is, since the piezoelectric vibrating part 60 and the vibration exciting part 91 are in contact, the vibration of the piezoelectric element is transmitted to the contact surface such as a desk via the vibration exciting part 91. On the other hand, the second position in FIG. 6B is used when no sound is generated from the mobile phone 10. In this case, since the piezoelectric vibrating portion 60 and the exciting portion 91 are not in contact, the vibration of the piezoelectric element is not transmitted to the contact surface. Further, in the non-contact state, the piezoelectric vibrating part 60 is protected by the cover part 90. Therefore, for example, even if the mobile phone 10 is dropped and an impact is applied to the side surface 20a from the place where the mobile phone 10 is dropped, the cover 90 receives the impact, so that the piezoelectric vibrating portion 60 can be protected from the impact during the fall.

  Further, the cover 90 functions as a switch for inputting a sound signal to the piezoelectric element 61. As shown in FIGS. 6A and 6B, the cover unit 90 includes a switch unit 93 at the end on the holding unit 901 side. The switch unit 93 includes, for example, a conductive metal, and the holding unit 901 has two terminals that are part of a circuit that inputs a sound signal to the piezoelectric element 61 on the end surface 901a. Then, at the first position of the cover portion 90, as shown in FIG. 6A, the switch portion 93 comes into contact with the end surface 901a, and the two terminals provided on the end surface 901a pass through the conductive metal of the switch portion 93. Connected. Then, a circuit for inputting a sound signal to the piezoelectric element 61 is conducted, and as a result of the signal being input to the piezoelectric element 61, the piezoelectric vibrating portion 60 is driven, and the vibration is transmitted to the contact surface via the vibrating portion 91. The In this way, the mobile phone 10 generates sound from the contact surface. On the other hand, when the cover portion 90 is displaced to the second position and the piezoelectric vibrating portion 60 and the vibrating portion 91 are in a non-contact state, this circuit is not conducted, so that no sound signal is input to the piezoelectric element 61 and the piezoelectric element 61 The vibration part 60 is not driven. Therefore, the mobile phone 10 does not generate sound.

  FIG. 7 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, and the stacked piezoelectric element 61 described above. Panel 30, input unit 40, display unit 50, 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. The control unit 130 applies a reproduction sound signal (a voltage corresponding to a reproduction sound signal of a call partner's voice or a ringing melody or music including music) to the stacked piezoelectric element 61 via the piezoelectric element driving unit 120. 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. 9 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 vibrating portion 91, the protruding portion 92, and the elastic member 70 will be described with reference to FIG. FIG. 10 shows a state in which the mobile phone 10 is placed on a horizontal contact surface 150 such as a desk with the side surface 20a facing downward when the cover 90 is in the first position. 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. 10, the mobile phone 10 is supported on the contact surface 150 at two points by the vibration unit 91 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. 10, 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 vibration unit 91 has a lowermost end 911. The lowermost end portion 911 is a portion of the vibrating portion 91 that comes into contact with the contact surface 150 when the mobile phone 10 is placed on the horizontal contact surface 150 such as a desk with the side surface 20a facing downward. The lowermost end portion 911 is, for example, the tip end portion of the cap 94.

  The mobile phone 10 has a lowermost end 201. It is assumed that the lowermost end portion 201 of the mobile phone 10 does not include the vibrating portion 91 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 abuts the contact surface 150. The lowermost end 201 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 201 of the mobile phone 10. The protrusion is, for example, a side key or a connector cap.

  In FIG. 10, 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 201 of the mobile phone 10 when it is assumed that the excitation unit 91 does not exist.

  In FIG. 10, 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 excitation unit 91 is provided on the side surface 20a on the region R2 side.

  The vibration unit 91 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. Thereby, the load applied to the vibration unit 91 via the piezoelectric vibration unit 60 becomes larger than that in the case where the vibration unit 91 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 lowermost end portion 911 of the excitation unit 91 is a one-dot chain line I when the voltage is not applied to the laminated piezoelectric element 61 and the laminated piezoelectric element 61 extends from the state where it does not expand or contract, or when the laminated piezoelectric element 61 has the maximum amplitude. It is better to be located closer to the contact surface 150 side. That is, the lowermost end portion 911 is more in contact with the multi-layer piezoelectric element 61 than the one-dot chain line I when the multi-layer piezoelectric element 61 is stretched most from the state where the multi-layer piezoelectric element 61 does not expand or contract or when the multi-layer 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.

  In addition, the lowermost end portion 911 of the excitation unit 91 is formed when the laminated piezoelectric element 61 is contracted the 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 lowermost end portion 911 is one point at the minimum amplitude of the multilayer piezoelectric element 61 when no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 contracts most from the state where the multilayer piezoelectric element 61 does not expand or contract. It is preferable that the contact surface 150 protrudes from the chain line I. In addition, the protrusion 92 is an alternate long and short dash line when the multilayer piezoelectric element 61 is contracted the most from the state in which no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand or contract. It is better to be located closer to the housing 20 than I. Thereby, the lowermost end 201 and the protrusion 92 of the mobile phone 10 are less likely to contact the contact surface 150. For example, depending on the type of coating of the housing 20, the coating is difficult to peel off. Further, abnormal noise is less likely to occur between the lowermost end 201 or the protrusion 92 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 vibration unit 91 and the elastic member 70, and further supported by a stand.

  FIGS. 11A, 11B, and 11C are schematic diagrams for explaining an operation as a sound generator by the mobile phone 10 according to the present embodiment. When the mobile phone 10 is to function as a sound generator, the cover 90 is in the first position, and the mobile phone 10 has the side surface 20a side of the housing 20 downward as shown in FIG. The cap 94 and the elastic member 70 of the vibration unit 91 are 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 excitation unit 91 via the piezoelectric vibration unit 60 as a load. That is, the mobile phone 10 functions as a weight of the sound generator according to the present invention. The state shown in FIG. 11A shows a state in which no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 is not expanded or contracted.

  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 expands and contracts. FIG. 11B exaggerates the state when the laminated piezoelectric element 61 is extended. The vibration portion 91 receives a force from the piezoelectric vibration portion 60 and the cover portion 90 bends, whereby the contact surface from the housing 20 is more than the stationary state of the multilayer piezoelectric element 61 (the state shown in FIG. 11A). Projects to the 150 side. FIG. 11C exaggerates the state when the multilayer piezoelectric element 61 is contracted. At this time, when the load of the mobile phone 10 is applied, the cover 90 is bent, and the excitation unit 91 is retracted to the housing 20 side from the stationary state of the multilayer piezoelectric element 61. In this way, by repeating the state shown in FIGS. 11B and 11C, the vibrating portion 91 has the cap 94 from the contact surface 150 with the contact portion of the elastic member 70 contacting the contact surface 150 as a fulcrum. It vibrates according to the reproduced sound signal without being separated. In addition, if there is no inconvenience that the lower end portion 201 comes into contact with the contact surface 150 to generate abnormal noise, the lower end portion 201 may be slightly 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. Thereby, the expansion and contraction vibration of the multilayer piezoelectric element 61 is transmitted to the contact surface 150 through the excitation unit 91 and the contact surface 150 vibrates, and the contact surface 150 functions as a vibration speaker and generates sound from the contact surface 150. If the difference between the length when stretched most and the length when shrunk most is less than 0.05 μm, the contact surface may not be vibrated properly. On the other hand, if it exceeds 50 μm, the vibration will increase. There is a risk that the sound generator will rattle.

  Here, as described above, the tip of the cap 94 is portable with the lowermost end 701 of the elastic member 70 when it is assumed that the vibrating portion 91 does not exist when the multilayer piezoelectric element 61 is extended most. It is good to be located on the contact surface 150 side with respect to a line (one-dot chain line I in FIG. 10) connecting the lowermost end portion 201 of the telephone 10. The tip of the cap 94 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 surface 20b and the tip of the protruding portion 63b shown in FIG. 5 is the most contracted state 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 may be longer than the amount of displacement at that time. As a result, even when the multilayer piezoelectric element 61 is in the most contracted state (the state shown in FIG. 11C), the vibration of the multilayer piezoelectric element 61 is not separated from the protrusion 63b, and the contact surface 150 is vibrated. Can be communicated to.

  The arrangement location of the excitation unit 91 and the piezoelectric vibration unit 60, the length of the stacked piezoelectric element 61 in the stacking direction, the size of the cap 94, 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 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, a stack type stacked piezoelectric element 61 is used as the piezoelectric element, and the expansion and contraction vibration is transmitted along the stacking direction by the reproduced sound signal, and the expansion and contraction vibration is transmitted to the contact surface 150. The vibration transmission efficiency in the deformation direction) is good, and the contact surface 150 can be vibrated efficiently. In addition, since the multilayer piezoelectric element 61 is brought into contact with the vibrating portion 91 via the covering member 63, the multilayer piezoelectric element 61 can be prevented from being damaged. Further, when the mobile phone 10 is placed sideways and the cap 94 of the excitation unit 91 is brought into contact with the contact surface 150, the weight of the mobile phone 10 is applied as a load to the cap 94 via the piezoelectric vibration unit 60. 94 can be reliably brought into contact with the contact surface 150, and the expansion and contraction vibration of the piezoelectric vibrating portion 60 can be efficiently transmitted to the contact surface 150.

  In addition, according to the sound generator according to the present embodiment, when the sound generator is not used to generate sound, the cover 90 is operated so that the piezoelectric vibration unit 60 and the vibration unit 91 are not in operation. It can be in contact. By doing so, since the piezoelectric vibration part 60 is covered with the cover part 90, it is protected from an external impact. Furthermore, according to the sound generator according to the present embodiment, the switching between the first position and the second position due to the displacement of the cover 90 is linked to the function of switching the sound signal to the piezoelectric element 61. Therefore, when the sound generator is not used to generate sound, the piezoelectric vibration unit 60 and the excitation unit 91 are brought into a non-contact state by displacing the cover unit 90 to the second position, and the piezoelectric element 61 It is possible to prevent the sound signal from being input to the. In this way, by operating the operation of the cover 90 and the switching function of the sound signal to the piezoelectric element 61, the operation can be simplified as compared with the case where the cover 90 and the switch are provided separately. it can.

  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, unlike the case of transmitting the vibration of the multilayer piezoelectric element to another elastic body. 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 of the times from when the other elastic body is deformed by the piezoelectric element until it returns to the deformable state. 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 piezoelectric element.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, the structure for fixing the piezoelectric vibrating portion 60 to the holding portion 100 is not limited to that shown in FIG. As shown in FIGS. 12A to 12C, the piezoelectric vibrating unit 60 may be held by the holding unit 100. The holding unit 100 shown in FIG. 12A includes a wide slit 101a that opens to the surface 20b, 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 surface 20 b 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. 12B includes a tapered slit 101c that expands toward the surface 20b, 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. 12A 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. 12C 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 through 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 FIG. 8, 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. 8, 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, the cover 90 is disposed on the side surface 20a of the housing 20 and the excitation unit 91 protrudes from the side 20a. 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, for example, the piezoelectric vibration part 60 and the cover part 90 may be provided on the battery lid 21, and the vibration part 91 may protrude from the battery lid 21.

  Moreover, the cover part 90 is not restricted to what slides on the side surface 20a to a longitudinal direction, as shown in FIG. For example, as shown in FIG. 13, the cover 90 may have a circular shape and may be configured to be operated by being rotated in the direction of the arrow 910.

  FIG. 14 is a diagram illustrating the operation of the circular cover portion. FIG. 14A shows a contact state between the piezoelectric vibrating portion 60 and the vibrating portion 91, and at this time, the cover portion 90 is in the first position. FIG.14 (b) is AA sectional drawing of Fig.14 (a). FIG. 14C shows a non-contact state between the piezoelectric vibrating portion 60 and the vibrating portion 91, and at this time, the cover portion 90 is in the second position. FIG.14 (d) is AA sectional drawing of FIG.14 (c). The user of the mobile phone 10 operates the protrusion 92 to displace the cover 90 (vibration unit 91) in the rotation direction, and switches between the first position and the second position, so that the piezoelectric vibration unit 60 can be switched between a contact state and a non-contact state between the vibration unit 91 and the vibration unit 91. The first position in FIG. 14A is used when sound is generated from the mobile phone 10. That is, as shown in FIG. 14B, since the piezoelectric vibrating portion 60 and the vibrating portion 91 are in contact, the vibration of the piezoelectric element is transmitted to the contact surface such as a desk via the vibrating portion 91. The On the other hand, the second position in FIG. 14C is used when no sound is generated from the mobile phone 10. In this case, as shown in FIG. 14D, since the piezoelectric vibrating portion 60 and the vibrating portion 91 are not in contact, the vibration of the piezoelectric element is not transmitted to the contact surface. Further, in the non-contact state, the piezoelectric vibrating part 60 is protected by the cover part 90. Therefore, for example, even if the mobile phone 10 is dropped and an impact is applied to the side surface 20a from the place where the mobile phone 10 is dropped, the cover 90 receives the impact, so that the piezoelectric vibrating portion 60 can be protected from the impact during the fall.

  The circular cover 90 functions as a switch for inputting a sound signal to the piezoelectric element 61. As shown in FIG. 14B, the circular cover 90 is, for example, a conductive metal on the opposite side of the excitation unit 91 across the rotation shaft of the cover 90 and on the inner side of the housing 20. The switch part 93 which has is provided. The holding member 210 that is a part of the housing 20 that holds the cover 90 has two terminals that are part of a circuit that inputs a sound signal to the piezoelectric element 61 on the contact surface 210a. Then, at the first position of the cover portion 90, as shown in FIG. 14B, the switch portion 93 is in contact with the contact surface 210a, and the two terminals provided on the contact surface 210a are the conductive metal of the switch portion 93. Connected through. Then, a circuit for inputting a sound signal to the piezoelectric element 61 is conducted, and as a result of the signal being input to the piezoelectric element 61, the piezoelectric vibrating portion 60 is driven, and the vibration is transmitted to the contact surface via the vibrating portion 91. The In this way, the mobile phone 10 generates sound from the contact surface. On the other hand, when the cover portion 90 is displaced to the second position and the piezoelectric vibrating portion 60 and the vibrating portion 91 are in a non-contact state, this circuit is not conducted, so that no sound signal is input to the piezoelectric element 61 and the piezoelectric element 61 The vibration part 60 is not driven. Therefore, the mobile phone 10 does not generate sound.

  Further, the cover portion is not limited to the shape shown in FIG. 6 or FIG. For example, as shown in FIG. 15A, the cover portion 90 may include a constricted portion 95 having a thickness smaller than that of the cover portion 90 at both ends of the vibration portion 91. By providing the constricted portion 95, the vibration portion 91 is likely to vibrate, so that the vibration of the piezoelectric element 61 can be transmitted to the contact surface 150 more efficiently. For example, as illustrated in FIG. 15B, the cover 90 may include a taper portion 96 on the side of the piezoelectric vibration portion 60 in the vibration portion 91. By providing the taper portion 96, when the cover portion 90 is displaced from the second position to the first position, the piezoelectric vibration portion 60 and the vibration portion 91 do not interfere with each other and reliably. The cover 90 can be smoothly displaced so that 60 and the cover 90 are in contact with each other.

  Further, the switch unit 93 is not limited to the above embodiment. For example, as the switch unit 93, a detection switch that detects whether or not the end portion having the switch unit 93 in the cover unit 90 is in contact with the end surface 901a, that is, whether or not the cover unit 90 is in the first position. The cover 90 may be provided. In this case, when the detection switch detects that the cover portion 90 is in the first position, it inputs a sound signal to the piezoelectric element 61 and does not detect that the cover portion 90 is in the first position. That is, when the cover 90 is in the second position, the sound signal is not input to the piezoelectric element 61.

  In addition, for example, the vibration part 91 may omit the cap 94 and may contact the contact surface with the tip surface of the vibration part 91 directly or via a vibration transmission member made of an insulating member or the like. Further, the protrusion 92 may be omitted. In this case, the user can move the cover unit 90 by moving the vibration unit 91 with a finger, for example.

  Moreover, although said to-be-contacted member was a desk and said contact surface was a horizontal contact 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, a variety of 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 Cellular phone 20 Case 20a Side surface 20b Surface 21 Battery lid 30 Panel 40 Input part 50 Display part 60 Piezoelectric vibration part 61 Multilayer piezoelectric element (piezoelectric element)
62 O-ring 63 Cover member 90 Cover part 91 Exciting part 92 Protruding part 93 Switch part 94 Cap part 95 Constriction part 96 Taper part 100 Holding part 101 Slit 110 Wireless communication part 120 Piezoelectric element drive part 121 Signal processing circuit 122 Booster circuit 123 Low pass filter (LPF)
130 Control unit 150 Contact surface 900, 901 Holding unit 901a End surface

Claims (4)

A housing,
A piezoelectric vibrating portion having a piezoelectric element disposed in the housing;
A vibration unit capable of taking a non-contact state that does not contact the piezoelectric vibration unit and a contact state that contacts the piezoelectric vibration unit;
A weight for applying a load to the excitation part via the piezoelectric vibration part,
In the contact state, in a state where a load from the weight is applied to the excitation unit, the piezoelectric vibration unit is deformed according to a sound signal, and the excitation unit is contacted by deformation of the piezoelectric vibration unit Vibrating the surface to generate sound from the contact surface,
Sound generator. In the contact state, the excitation unit is in contact with the piezoelectric vibration unit on a side closer to the contact surface than the piezoelectric vibration unit.
The sound generator according to claim 1. The excitation unit can take the non-contact state and the contact state by sliding and displacing in a direction along the surface of the housing.
The sound generator according to claim 1 or 2. The contact surface is a mounting surface on which the sound generator is mounted.
The sound generator according to any one of claims 1 to 3.

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