JP6267033B2 - 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.

  As a conventional vibration generator, there is one described in Patent Document 1, for example. Patent Document 1 describes a vibration generator having a dynamic speaker structure including a magnet, a voice coil, a diaphragm, and a case for housing these. Japanese Patent Application Laid-Open No. H10-228688 discloses a weight having an elastic body, the weight causing a deformation such as a curve due to the vibration of the piezoelectric vibrator, and vibrating the body to be vibrated by this deformation. . Further, Patent Document 3 discloses an elastic body that receives a weight load and causes deformation such as bending due to vibration of a piezoelectric vibrator, and vibrates the body to be vibrated by this deformation. Further, Patent Document 4 discloses that an elastic body undergoes deformation such as bending due to vibration of a piezoelectric vibrator, and vibrates a body to be vibrated by this deformation.

Japanese Utility Model Publication No. 5-85192 JP 2007-74663 A JP 2009-27413 A JP 2009-27320 A

  The vibration generating device described in Patent Document 1 has a dynamic speaker structure and uses various members such as a magnet, a voice coil, a diaphragm, and a case for housing them, so an increase in the number of parts of the device can be avoided. Absent. In addition, the devices described in Patent Documents 2 to 4 use piezoelectric elements as vibrating bodies, but these devices have an elastic body inside the device in order to ensure the degree of freedom of deformation of the elastic body. It is necessary to provide a space that can be bent, and an increase in the size of the apparatus is inevitable.

  An object of the present invention made in view of such a viewpoint is to provide a sound generator that can be simply configured.

  A first aspect of a sound generator according to the present invention that achieves the above object includes a plurality of piezoelectric vibrating portions having piezoelectric elements and a weight that applies a load to the piezoelectric vibrating portion, and the weight is attached to the piezoelectric vibrating portion. In a state where a load from is applied, applying a sound signal to the piezoelectric element deforms the piezoelectric element and deforms the piezoelectric vibration part, and contacts the sound generator by the deformation of the piezoelectric vibration part. The surface is vibrated to generate sound from the contact surface.

  According to a second aspect of the sound generator of the present invention, in the first aspect, the plurality of piezoelectric vibrating portions are arranged on a virtual plane perpendicular to the expansion / contraction direction of the piezoelectric element.

  According to a third aspect of the sound generator of the present invention, in the first aspect, the plurality of piezoelectric vibrating portions are arranged on a virtual straight line parallel to the expansion / contraction direction of the piezoelectric element.

  In a fourth aspect of the sound generator according to the present invention, stereo sound is input to the piezoelectric vibrating portion in the first aspect.

  According to a fifth aspect of the sound generator of the present invention, in the first aspect, three piezoelectric elements are arranged on the bottom surface.

  Moreover, the 6th aspect of the sound generator which concerns on this invention is provided with the loudspeaker driven simultaneously with the said piezoelectric vibration part in the said 1st aspect.

  ADVANTAGE OF THE INVENTION According to this invention, the sound generator which can be comprised simply can be provided.

1 is an external perspective view of a vibration speaker that is an embodiment of a sound generator according to the present invention. It is a schematic perspective view of the piezoelectric vibration part of the vibration speaker of FIG. It is a schematic sectional drawing of the vibration speaker of FIG. It is a figure which shows the structure of the laminated piezoelectric element of FIG. It is a figure which shows the modification of a lamination type piezoelectric element. It is a partial expanded sectional view of the piezoelectric vibration part of FIG. It is a functional block diagram of the principal part of the vibration speaker 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 vibration speaker of FIG. It is a figure which shows the three modifications of the holding | maintenance aspect of a piezoelectric vibration part. It is a figure which shows schematic structure of the principal part which shows the modification of a piezoelectric vibration part. It is a schematic sectional drawing of the vibration speaker which is a modification of the sound generator which concerns on this invention. It is a schematic sectional drawing of the vibration speaker which is a modification of the sound generator which concerns on this invention. It is a schematic sectional drawing of the vibration speaker which is a modification of the sound generator which concerns on this invention. FIG. 17 is a schematic bottom view of the vibration speaker shown in FIG. 16.

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

  FIG. 1 is an external perspective view of a vibration speaker that is a sound generator according to an embodiment of the present invention. The sound generator according to the present embodiment functions as the vibration speaker 10 and includes the piezoelectric vibration unit 60 a and the piezoelectric vibration unit 60 b and the elastic member 70. As will be described later, the vibration speaker 10 functions as a weight (weight of a sound generator) that applies a load to the piezoelectric vibrating portion 60a and the piezoelectric vibrating portion 60b. The vibration speaker 10 includes a housing 20 whose external shape is substantially rectangular. The piezoelectric vibrating portion 60 a and the piezoelectric vibrating portion 60 b and the elastic member 70 are formed on the bottom surface 20 a of the vibration speaker 10 that is one surface of the housing 20.

  The sound generator according to the present embodiment has a piezoelectric vibrating portion 60a and a piezoelectric vibrating portion 60b for a sound generator and a sheet-like elastic member 70 on the bottom surface 20a side of one long side of the casing 20 of the vibration speaker 10. With. The elastic member 70 is made of, for example, rubber, silicone, polyurethane, or the like. When the vibration speaker 10 is placed on a horizontal placement surface such as a desk with the bottom surface 20a facing down, the vibration speaker 10 has three points on the placement surface by the piezoelectric vibration portion 60a, the piezoelectric vibration portion 60b, and the elastic member 70. Supported by The arrangement of the piezoelectric vibrating portion 60a, the piezoelectric vibrating portion 60b, and the elastic member 70 will be described in detail later.

  FIG. 2 is a schematic perspective view of the piezoelectric vibrating portion 60a of the vibration speaker shown in FIG. 2 shows the configuration of the piezoelectric vibrating portion 60a, the configuration of the piezoelectric vibrating portion 60b is the same. The vibration speaker 10 according to the present embodiment includes a holding unit that houses and holds the piezoelectric vibrating unit 60 a and the piezoelectric vibrating unit 60 b on the bottom surface side of the housing 20. The holding portion extends along the longitudinal direction of the housing 20.

  In other words, in the vibration speaker 10 according to the present embodiment, the piezoelectric vibration unit 60a and the piezoelectric vibration unit 60b are arranged on the bottom surface 20a side of the housing 20 as shown in FIG. Are arranged on a virtual plane T perpendicular to the expansion / contraction direction of the piezoelectric element constituting the. FIG. 3 is a schematic cross-sectional view of the vibration speaker of FIG.

  The piezoelectric vibrating portion 60a includes a piezoelectric element 610a, a waterproof O-ring 62, and an insulating cap 63 that is a covering member. The piezoelectric element 610a 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 610a may be a unimorph, bimorph, or multilayer piezoelectric element. The multilayer piezoelectric element includes a multilayer bimorph element in which bimorphs are stacked (for example, 16 layers or 24 layers), a plurality of dielectric layers made of, for example, PZT (lead zirconate titanate), and the plurality of dielectrics. There is a stack type composed of a laminated structure with electrode layers arranged between 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 610a is a stack-type stacked piezoelectric element. The laminated piezoelectric element 610a 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 610a shown in FIGS. 4A and 4B has a first lead connection portion 61e electrically connected to the first side surface electrode 61c and a second side surface electrode 61d on one end surface. 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 610a 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 610a 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 610a and the cross-sectional area of the laminated piezoelectric element 610a depend on the weight of the vibration speaker 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.

  A sound signal (reproduced sound signal) is supplied to the multilayer piezoelectric element 610a from the control unit 130 via a piezoelectric element driving unit 120 described later. In other words, a voltage corresponding to the sound signal is applied from the control unit 130 to the stacked piezoelectric element 610 a 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 610a expands and contracts from a state where no voltage is applied. The direction of expansion / contraction of the stacked piezoelectric element 610a 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 610a substantially coincides with the lamination direction of the dielectric 61a and the internal electrode 61b. Since the multilayer piezoelectric element 610a expands and contracts substantially along the stacking direction, there is an advantage that vibration transmission efficiency in the stretching direction is good.

  Such a multilayer piezoelectric element 610a has been conventionally used for fuel injection control of automobiles. The present inventor has confirmed through experiments that the multilayer piezoelectric element 610a operates sufficiently effectively as a vibration element for generating sound from a contact surface where the sound generator contacts a desk or the like.

  4A and 4B, 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. 4A and 4B, as shown in FIG. 5, the first lead connecting portion 61e and the second lead connecting portion 61f include a first side electrode 61c and a first side electrode 61c at one end of the multilayer piezoelectric element 610a. You may form in the 2nd side electrode 61d. FIG. 5 is a schematic view of a modification of the multilayer piezoelectric element applicable to the sound generator according to the present invention.

  In addition, as shown in the partial enlarged cross-sectional view of FIG. 6, the laminated piezoelectric element 610 a has a side surface at one end having the first lead connection portion 61 e and the second lead connection portion 61 f that is a slit of the holding portion 100 of the housing 20. 101 is fixed via an adhesive 102 (for example, epoxy resin). A cap 63 is inserted into the other end of the multilayer piezoelectric element 610 a and is fixed by the adhesive 102.

  The cap 63 is formed of a material that can reliably transmit the expansion and contraction vibration caused by the laminated piezoelectric element 610a 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 is formed with an entry portion located in the slit 101 and a projection portion protruding from the housing 20 in a state of being attached to the multilayer piezoelectric element 610 a, and the entry portion located in the slit 101. A waterproof O-ring 62 is disposed on the outer periphery of the lens. The O-ring 62 is made of, for example, silicone. O-ring 62 makes it difficult for water or dust to enter the slit 101. Further, the protrusion has a hemispherical tip. Note that the tip of the protruding portion is not limited to a hemispherical shape, and may have a shape that can reliably make point contact or surface contact with a mounting surface (contact surface) such as a desk and transmit expansion and contraction vibrations by the multilayer piezoelectric element 610a. Any shape can be used. In FIG. 6, the gap between the O-ring 62 and the adhesive portion of the multilayer piezoelectric element 610a to the slit 101 can be filled with gel or the like to further enhance the waterproof effect. The piezoelectric vibrating portion 60 a is attached to the holding portion 100, and the protruding portion of the cap 63 protrudes from the bottom surface 20 a of the housing 20 with the battery lid attached to the housing 20. Further, the protruding portion 63 b of the cap 63 has a facing surface 63 c that is a surface facing the bottom surface 20 a of the housing 20. As shown in FIG. 6, the opposing surface 63c is separated from the bottom surface 20a by a length d in a state where no voltage is applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610a does not expand and contract.

  FIG. 7 is a functional block diagram of a main part of the vibration speaker 10 according to the present embodiment. The vibration speaker 10 includes a panel 30 that detects a contact position of a user's finger or the like based on a change in capacitance, an input unit 40 that inputs an operation such as a reproduction instruction, a display unit 50 that displays an image, an operation state, and the like. In addition to the piezoelectric element 610a and the laminated piezoelectric element 610b, a wireless communication unit 110, a piezoelectric element driving unit 120, a control unit 130, a memory 140, a detection switch 170, and a loudspeaker 160 are provided. Panel 30, input unit 40, display unit 50, wireless communication unit 110, piezoelectric element driving unit 120, memory 140, detection switch 170, and loud speaker 160 are connected to control unit 130. The multilayer piezoelectric element 610 a and the multilayer piezoelectric element 610 b are connected to the control unit 130 via the piezoelectric element driving unit 120. The panel 30 and the display unit 50 are integrated to form a touch panel.

  The wireless communication unit 110 has a known configuration, and is wirelessly connected to another terminal or a communication network via a short-range remote wireless communication standard, infrared rays, or the like. The control unit 130 is a processor that controls the overall operation of the vibration speaker 10. The control unit 130 applies a reproduction sound signal (a voltage corresponding to a reproduction sound signal such as a voice of a call partner or a ringing melody or music including music to the stacked piezoelectric element 610a and the stacked piezoelectric element 610b via the piezoelectric element driving unit 120. ) 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 memory 140 stores various programs and data used by the control unit 130. The detection switch 170 is configured by, for example, an illuminance sensor, an infrared sensor, a mechanical switch, and the like, detects that the vibration speaker 10 is placed on a placement surface such as a desk or table, and outputs the output to the control unit 130. Output. Based on the detection result of the detection switch 170, the control unit 130 controls, for example, on / off of the operations of the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b. The loudspeaker 160 is a speaker that outputs sound under the control of the control unit 130.

  The booster circuit 122 boosts the voltage of the input analog reproduction sound signal and applies it to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b via the LPF 123. Here, the maximum voltage of the reproduced sound signal applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b by the booster circuit 122 can be set to, for example, 1 Vpp to 500 Vpp, but is not limited to this range. The weight can be adjusted as appropriate according to the weight of the multilayer piezoelectric element 610a and the performance of the multilayer piezoelectric element 610b. Note that the reproduction sound signal applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b may be biased with a DC voltage, or a maximum voltage may be set around the bias voltage.

  Further, not only the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b, the piezoelectric element generally has a larger power loss at higher frequencies, and therefore the LPF 123 attenuates or cuts at least a part of the frequency component of about 10 kHz to 50 kHz or more. It is set to have a frequency characteristic or a frequency characteristic in which the attenuation rate increases gradually or stepwise. FIG. 9 shows, as an example, frequency characteristics of the LPF 123 when the cutoff frequency is about 20 kHz. Thus, by attenuating or cutting the high-frequency component, power consumption can be suppressed and heat generation of the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b can be suppressed.

  Further, the loudspeaker 160 is driven under the control of the control unit 130, and a reproduced sound signal is input to generate sound. This audio signal may be the same as or different from the reproduced sound signal applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b. The loudspeaker 160 is simultaneously driven when a reproduction sound signal is applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b, and is driven simultaneously with the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610b. It may be done.

  Next, the arrangement of the piezoelectric vibrating portion 60a, the piezoelectric vibrating portion 60b, and the elastic member 70 will be described with reference to FIG. FIG. 10 shows a state where the vibration speaker 10 is placed on a horizontal placement surface 150 such as a desk with the bottom surface 20a side downward. Here, the desk is an example of the contacted member of the present invention, and the placement surface 150 is an example of a contact surface (placement surface) with which the sound generator contacts. As shown in FIG. 10, the vibration speaker 10 is supported at two points on the mounting surface 150 by the piezoelectric vibrating portion 60 a, the piezoelectric vibrating portion 60 b, and the elastic member 70. Point G is the center of gravity of the vibration speaker 10. That is, point G is the center of gravity of the sound generator weight. In FIG. 10, for simplicity, the piezoelectric vibrating portion 60b is not shown, but the following description also applies to the piezoelectric vibrating portion 60b.

  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 placement surface 150 when the vibration speaker 10 is placed on a horizontal placement surface 150 such as a desk with the bottom surface 20a facing downward.

  The piezoelectric vibrating part 60 a has a lowermost end part 601. The lowermost end portion 601 is a portion of the piezoelectric vibration portion 60a that comes into contact with the placement surface 150 when the vibration speaker 10 is placed on a horizontal placement surface 150 such as a desk with the bottom surface 20a side down. . The lowermost end 601 is, for example, the tip of the cap 63.

  The vibration speaker 10 has a lowermost end portion 101. The lowermost end 101 is assumed that, when the vibration speaker 10 is placed on a horizontal placement surface 150 such as a desk with the bottom surface 20a facing down, the piezoelectric vibration portion 60a does not exist. In this case, it is a place that comes into contact with the mounting surface 150. The lowermost end 101 of the vibration speaker 10 is, for example, a corner of the housing 20, but is not limited thereto. When the bottom surface 20 a is provided with a protruding portion that protrudes from the bottom surface 20 a, the protruding portion may be the lowermost end portion 101 of the vibration speaker 10. The protrusion is, for example, a side key or a connector cap.

  In FIG. 10, a dotted line L indicates that the vibration speaker 10 passes through the center of gravity G of the vibration speaker 10 and is perpendicular to the placement surface 150 when the vibration speaker 10 is placed on a horizontal placement surface 150 such as a desk with the bottom surface 20a facing downward. A straight line (virtual line). The alternate long and short dash line I is a line (virtual line) connecting the lowermost end 701 of the elastic member 70 and the lowermost end 101 of the vibration speaker 10 when it is assumed that the piezoelectric vibrating portion 60a 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 vibration speaker 10. The region R2 is a region on the other side delimited by the dotted line L in the vibration speaker 10. The elastic member 70 is provided on the side of the region R1 on the bottom surface 20a. The piezoelectric vibrating portion 60a is provided on the region R2 side on the bottom surface 20a.

  The piezoelectric vibrating portion 60a is preferably provided at a position as close as possible to the dotted line L on the region R2 side of the bottom surface 20a. As a result, the load applied to the piezoelectric vibrating portion 60a becomes larger than when the piezoelectric vibrating portion 60a is provided at a position separated from the dotted line L on the region R2 side of the bottom surface 20a. Thereby, the vibration speaker 10 can be effectively utilized as a 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 bottom surface 20a. As a result, even when the piezoelectric vibrating portion 60a is provided as close as possible to the dotted line L, a sufficient distance between the elastic member 70 and the piezoelectric vibrating portion 60a is secured, and the sound generator is stably placed. It can be mounted on.

  The lowermost end 601 of the piezoelectric vibrating portion 60a is a one-dot chain line I when the voltage is not applied to the laminated piezoelectric element 610a and the laminated piezoelectric element 610a extends most from a state where it does not expand or contract or when the laminated piezoelectric element 610a has the 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 one-dot chain line I when no voltage is applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610a extends most from a state where it does not expand or contract or when the multilayer piezoelectric element 610a 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 60a.

  The lowermost end 601 of the piezoelectric vibrating portion 60a is provided when the stacked piezoelectric element 610a contracts the most from the state in which no voltage is applied to the stacked piezoelectric element 610a and the stacked piezoelectric element 610a does not expand or contract, or the stacked piezoelectric element 610a. 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 lowermost end 601 is one point at the minimum amplitude of the multilayer piezoelectric element 610a when the multilayer piezoelectric element 610a is most contracted from the state in which the multilayer piezoelectric element 610a is not expanded or contracted because no voltage is applied to the multilayer piezoelectric element 610a. It is good to protrude from the chain line I to the mounting surface 150 side. As a result, the lowermost end portion 101 of the vibration speaker 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 difficult to peel off. Further, abnormal noise is less likely to occur between the lowermost end portion 101 and the placement surface 150.

  The vibration speaker 10 may be placed on a mounting surface such as a desk with a commercially available stand or the like attached to the housing 20 with the bottom surface 20a facing downward. In this case, the bottom surface 20a of the vibration speaker 10 is supported at two points by the piezoelectric vibrating portion 60a 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 vibration speaker 10 according to the present embodiment. In the following description, the piezoelectric vibrating portion 60a will be described as an example, but the same description applies to the piezoelectric vibrating portion 60b. When the vibration speaker 10 functions as a sound generator, the vibration speaker 10 has the bottom surface 20a side of the housing 20 downward and the cap 63 and the elastic member 70 of the piezoelectric vibration portion 60a as shown in FIG. Is placed sideways so as to be in contact with a placement surface (contact surface) 150 such as a desk. Thereby, the weight of the vibration speaker 10 is given to the piezoelectric vibration part 60a as a load. That is, the vibration speaker 10 functions as a weight of the sound generator according to the present invention. In the state shown in FIG. 11A, the stacked piezoelectric element 610a does not expand and contract because no voltage is applied thereto.

  In this state, when the multilayer piezoelectric element 610a of the piezoelectric vibrating portion 60a is driven by the reproduction sound signal, the multilayer piezoelectric element 610a is mounted with the elastic member 70 as shown in FIGS. 11B and 11C. 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. If there is no inconvenience such as the lower end 101 contacting the placement surface 150 and generating abnormal noise, the lower end 101 may be separated slightly. The difference between the length when the multilayer piezoelectric element 610a is most expanded and the length when it is most contracted is, for example, 0.05 μm to 100 μm. Thereby, the expansion / contraction vibration of the multilayer piezoelectric element 610a is transmitted to the mounting surface 150 through the cap 63, and the mounting surface 150 vibrates, and the mounting surface 150 functions as a vibration speaker and generates sound from the mounting surface 150. To do. If the difference between the length when it is most stretched and the length when it is most contracted is less than 0.05 μm, the mounting surface may not be vibrated properly. On the other hand, if it exceeds 100 μm, vibration due to the frequency may occur. May increase and the sound generator may rattle. Moreover, even if it is less than 100 μm, there is a possibility that it is not stable due to the relationship between the load and the frequency.

  Here, as described above, the tip end portion of the cap 63 vibrates with the lowermost end portion 701 of the elastic member 70 when it is assumed that the piezoelectric vibrating portion 60a does not exist when the stacked piezoelectric element 610a is most extended. It is preferable to be positioned closer to the placement surface 150 than a line connecting the lowermost end portion 101 of the speaker 10 (a chain line I in FIG. 10). Further, the tip of the cap 63 may be positioned closer to the mounting surface 150 than the virtual line when the stacked piezoelectric element 610a is contracted most.

  Further, the distance d between the bottom surface 20a and the facing surface 63c of the cap 63 shown in FIG. 6 is the state where the voltage is not applied to the multilayer piezoelectric element 610a and the multilayer piezoelectric element 610a is contracted most from the state where it does not expand and contract. It is better to be longer than the amount of displacement when This makes it difficult for the bottom surface 20a of the housing 20 and the cap 63 to come into contact with each other even when the multilayer piezoelectric element 610a is contracted most (the state shown in FIG. 11C). Therefore, it is difficult for the cap 63 to fall off the piezoelectric element 610a.

  The arrangement location on the bottom surface 20a of the piezoelectric element portion 60, the length of the stacked piezoelectric element 610a 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 vibration speaker as the sound generator according to the present embodiment, since the piezoelectric element is used as the vibration source, the number of parts can be reduced and reduced compared to the conventional vibration generator having a dynamic speaker structure. It can be easily configured with the number of parts. Further, the stack type stacked piezoelectric element 610a 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 mounting surface (contact surface) 150. The vibration transmission efficiency in the expansion / contraction direction (deformation direction) with respect to the surface (contact surface) 150 is good, and the placement surface (contact surface) 150 can be vibrated efficiently. Moreover, since the multilayer piezoelectric element 610a is brought into contact with the mounting surface (contact surface) 150 via the cap 63, the multilayer piezoelectric element 610a can be prevented from being damaged. Further, when the vibration speaker 10 is placed sideways and the cap 63 of the piezoelectric vibration unit 60a is brought into contact with the placement surface (contact surface) 150, the weight of the vibration speaker 10 is applied to the cap 63 as a load. It is possible to reliably contact the mounting surface (contact surface) 150 and efficiently transmit the expansion / contraction vibration of the piezoelectric vibrating portion 60 a to the mounting surface (contact surface) 150.

  In addition, the vibration speaker as the sound generator according to the present embodiment can mainly transmit the vibration of the multilayer piezoelectric element directly to the contact surface (mounting surface). Unlike the prior art that transmits to other elastic bodies, when generating sound, it does not depend on the limit frequency on the high frequency side where the 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.

  Further, in the sound generator according to the present embodiment, the piezoelectric vibration unit has two piezoelectric vibration units 60a and 60b in the expansion / contraction direction of the piezoelectric elements constituting the piezoelectric vibration unit 60a and the piezoelectric vibration unit 60b. Since it is provided on a vertical virtual plane, the stroke is one time and the output power can be doubled compared to the case where there is one piezoelectric vibration part. In addition, since the two piezoelectric vibration units 60a and 60b are provided, stereo sound can be obtained by inputting right and left sounds to the respective vibration units.

  Further, the structure for fixing the laminated piezoelectric vibration element 610a to the holding unit 100 is not limited to that shown in FIG. For example, as shown in FIGS. 12A to 12C, the multilayer piezoelectric vibration element 610 a may be held by the holding unit 100. In the following description, the multilayer piezoelectric vibration element 610a will be described as an example, but the same description applies to the multilayer piezoelectric vibration element 610b. The holding unit 100 shown in FIG. 12A includes a wide slit 101a that opens to the bottom surface 20a, and a narrow slit 101b that continues to the slit 101a. The laminated piezoelectric element 610 a has one end disposed in the narrow slit 101 b and the side surface fixed to the slit 101 b through the adhesive 102. The wide slit 101a 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 610a in the gap with the multilayer piezoelectric element 610a. If the piezoelectric vibration part 60a is held in the holding part 100 in this way, the vibration speaker 10 can be more reliably waterproofed without using a waterproof packing such as an O-ring. Further, by covering the portion protruding from the bottom surface 20a of the multilayer piezoelectric element 610a with an insulating cap, the multilayer piezoelectric element 610a can be reliably insulated.

  The holding unit 100 shown in FIG. 12B includes a tapered slit 101c that expands toward the bottom surface 20a, and a narrow slit 101d that continues to the tapered slit 101c. The laminated piezoelectric element 610 a has one end disposed in the narrow slit 101 d and the side surface fixed to the slit 101 d via the adhesive 102. The tapered slit 101c 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 610a in the gap with the multilayer piezoelectric element 610a. With this configuration, the same effect as that of the holding unit 100 of FIG. 12A can be obtained, and since the tapered slit 101c is provided, the multilayer piezoelectric element 610a 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 610a has an end surface on one end side via an adhesive 102. It is fixed to the slit 101. Further, a waterproof O-ring 62 is disposed at an appropriate location of the multilayer piezoelectric element 610a in the slit 101. Such a holding mode of the multilayer piezoelectric element 610a is particularly suitable when the multilayer piezoelectric element 610a has a lead wire connecting portion formed on a side electrode as shown in FIG. Etc. are advantageous.

  Further, in the above embodiment and the modified examples of FIGS. 12A to 12C, the piezoelectric vibrating portion 60a omits the cap 63, and the tip surface of the multilayer piezoelectric element 610a is formed directly or made of an insulating member or the like. You may make it contact a contact surface via a vibration transmission member. 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. FIG. 13 is a diagram showing a schematic configuration of a main part when a bimorph is used. The bimorph 65 has a long rectangular shape, one surface 65 a is exposed on the bottom surface 20 a of the housing 20, and both long ends are held by the holding unit 100. The holding unit 100 has an opening 101e that holds the bimorph 65, and the inner surface of the opening 101e on the back surface 65b side of the bimorph 65 is curved. According to this configuration, when the housing 20 is placed on the placement surface so that the bimorph 65 contacts the placement surface and the bimorph 65 is driven by the reproduction sound signal, the bimorph 65 bends (curves) and vibrates. Thereby, the vibration of the bimorph 65 is transmitted to the placement surface (contact surface), and the placement surface (contact surface) functions as a vibration speaker, and a reproduction sound is generated from the placement surface (contact surface). Note that a coating layer such as polyurethane may be formed on the surface 65 a of the bimorph 65.

  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-described embodiment, an example in which the piezoelectric vibrating portion 60a and the piezoelectric vibrating portion 60b are arranged on the bottom surface 20a of the housing 20 and protrude from the bottom surface 20a is shown, 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 60a and the piezoelectric vibration part 60b, the piezoelectric vibration part 60a may protrude from, for example, the side surface of the housing or the battery lid.

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 vibration speaker 10 was demonstrated to the example as a sound generator and the vibration speaker 10 was functioned as a weight, a weight is not restricted to this. For example, using a variety of electronic devices such as mobile phones, portable music players, stationary televisions, teleconferencing systems, notebook computers, projectors, wall clocks / wall televisions, alarm clocks, photo frames, etc. It can also be configured. 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.

(Modification 1)
Next, Modification 1 of the sound generator according to the present invention will be described with reference to FIG. FIG. 14 is a schematic cross-sectional view of a vibration speaker that is a first modification of the sound generator according to the present invention. Only differences from the embodiment described with reference to FIGS. 1 to 13 will be described below.

  In the present modification, as shown in FIG. 14, in the vibration speaker 10 according to the present embodiment, the piezoelectric vibrating portion 60 a and the piezoelectric vibrating portion 60 b are arranged on the bottom surface side of the housing 20. It arrange | positions on the virtual straight line L parallel to the expansion-contraction direction of the piezoelectric element which comprises 60b.

  As described above, in the sound generator according to the present embodiment, the piezoelectric vibration unit includes the piezoelectric vibration unit 60a and the piezoelectric vibration unit 60b, and the expansion and contraction of the piezoelectric elements constituting the piezoelectric vibration unit 60a and the piezoelectric vibration unit 60b. Since they are arranged on a virtual straight line parallel to the direction, the stroke is doubled and the output power can be doubled compared to the case where there is only one piezoelectric vibrating part.

(Modification 2)
Next, a second modification of the sound generator according to the present invention will be described with reference to FIG. FIG. 15 is a schematic cross-sectional view of a vibration speaker that is a second modification of the sound generator according to the present invention. Only differences from the embodiment described with reference to FIGS. 1 to 13 will be described below.

  In the present modification, as shown in FIG. 15, in the vibration speaker 10 according to the present embodiment, the piezoelectric vibration unit 60 a and the piezoelectric vibration unit 60 b are arranged on the bottom surface side of the housing 20. The piezoelectric elements constituting 60b are arranged on a virtual plane T perpendicular to the expansion / contraction direction of the piezoelectric element, and the distance therebetween is larger than that of the embodiment shown in FIG. That is, in the second modification, the piezoelectric vibrating portion 60 a and the piezoelectric vibrating portion 60 b are respectively disposed at the bottom side end portions of the housing 20.

  As described above, in the sound generator according to the present embodiment, the piezoelectric vibration unit includes the piezoelectric vibration unit 60a and the piezoelectric vibration unit 60b, and the expansion and contraction of the piezoelectric elements constituting the piezoelectric vibration unit 60a and the piezoelectric vibration unit 60b. Since it is provided on a virtual plane perpendicular to the direction, the stroke is 1 time and the output power can be doubled compared to the case where there is only one piezoelectric vibration part. In addition, since the two piezoelectric vibration units 60a and 60b are provided, stereo sound can be obtained by inputting right and left sounds to the respective vibration units. Furthermore, in the second modification, since the piezoelectric vibrating portion 60a and the piezoelectric vibrating portion 60b are arranged at the bottom side end portions of the casing 20, respectively, the sound quality of the stereo sound is more improved than the embodiment shown in FIG. Can be improved.

(Modification 3)
Next, Modification 3 of the sound generator according to the present invention will be described with reference to FIGS. 16 and 17 are schematic cross-sectional views of a vibration speaker which is a third modification of the sound generator according to the present invention. Only differences from the embodiment described with reference to FIGS. 1 to 13 will be described below.

  In this modification, as shown in FIGS. 16 and 17, in the vibration speaker 10 according to the present embodiment, three piezoelectric vibration units are arranged, that is, a piezoelectric vibration unit 60 a, a piezoelectric vibration unit 60 b, and a piezoelectric vibration unit 60 c. ing. In addition, the piezoelectric vibration part 60a, the piezoelectric vibration part 60b, and the piezoelectric vibration part 60c are respectively on the bottom surface side of the housing 20, and the expansion and contraction of the piezoelectric elements that constitute the piezoelectric vibration part 60a, the piezoelectric vibration part 60b, and the piezoelectric vibration part 60c. It is arranged on a virtual plane T perpendicular to the direction. Further, in the third modification, the piezoelectric vibrating portion 60a, the piezoelectric vibrating portion 60b, and the piezoelectric vibrating portion 60c are formed on the bottom surface side of the housing 20 so as to be arranged at the apex of the equilateral triangle. Of course, in the present invention, the arrangement relationship of the three piezoelectric vibrating portions is not limited to the case where each of them is at the apex of the skein equilateral triangle, but may be in any other appropriate position.

  As described above, in the sound generator according to the present embodiment, the piezoelectric vibrating unit includes the piezoelectric vibrating unit 60a, the piezoelectric vibrating unit 60b, and the piezoelectric vibrating unit 60c, the piezoelectric vibrating unit 60a, the piezoelectric vibrating unit 60b, and the piezoelectric vibrating unit. Since it is provided on a virtual plane perpendicular to the expansion / contraction direction of the piezoelectric element constituting the vibration unit 60c, the stroke is one time and the output power is three times that of a single piezoelectric vibration unit. Can do. In addition, since the piezoelectric vibration unit 60a, the piezoelectric vibration unit 60b, and the piezoelectric vibration unit 60c are provided, the third modification example further includes three of the piezoelectric vibration unit 60a, the piezoelectric vibration unit 60b, and the piezoelectric vibration unit 60c. Since the vibration speaker 10 can be supported by the above-described embodiment and the modification example, the two piezoelectric vibration units 60 that require separate feet for preventing the collapse are not necessary, Since the entire mass can be supported by the three piezoelectric vibrating parts, it is possible to support the mass stably, and there is no need for a separate foot and the efficiency is high.

  In the above-described embodiments and modifications, the case where there are two or three piezoelectric vibrating parts is illustrated, but in the sound generator of the present invention, the number of piezoelectric vibrating parts may be four or more. .

DESCRIPTION OF SYMBOLS 10 Vibration speaker 20 Case 20a Bottom surface 30 Panel 40 Input part 50 Display part 60a, 60b, 60c Piezoelectric vibration part 610a, 610b Multilayer piezoelectric element (piezoelectric element)
62 O-ring 63 Cap 70 Elastic member 110 Wireless communication unit 120 Piezoelectric element drive unit 121 Signal processing circuit 122 Booster circuit 123 Low pass filter (LPF)
130 Controller 150 Mounting surface (contact surface)
160 Loudspeaker 170 Detection switch

Claims (6)

A plurality of piezoelectric vibrators having a stacked piezoelectric element that expands and contracts along the stacking direction ;
A weight for applying a load to the piezoelectric vibrating portion;
Wherein in a state where a load is given from the weight to the piezoelectric vibrating unit, said by applying the sound signal to the laminated piezoelectric element to the laminated piezoelectric element is deformed to deform said piezoelectric vibrating portion, the piezoelectric vibration Vibrating the contact surface in contact with the sound generator by deformation of the part to generate sound from the contact surface;
Sound generator. 2. The sound generator according to claim 1, wherein the plurality of piezoelectric vibrating portions are arranged on a virtual plane perpendicular to an expansion / contraction direction of the multilayer piezoelectric element. The sound generator according to claim 1, wherein the plurality of piezoelectric vibration units are arranged on a virtual straight line parallel to an expansion / contraction direction of the multilayer piezoelectric element. With a housing,
4. The piezoelectric vibration unit according to claim 1, wherein one end in the stacking direction is fixed to the housing, and the other end in the stacking direction is opened to be able to contact the contact surface. The sound generator described in 1. The sound generator according to any one of claims 1 to 4, wherein a direction in which the multilayer piezoelectric element expands and contracts intersects the contact surface.   The sound generator according to claim 1, further comprising a loudspeaker driven simultaneously with the piezoelectric vibration unit.

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