JP6315674B2 - Sound generator and sound generation system - Google Patents

Description

  The present invention relates to a sound generator and a sound generation system that generate sound by vibrating a contact surface with which a sound generator contacts.

  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. However, these devices each include a weight, and an elastic body that is deformed by the weight of the weight by the piezoelectric element. Since the vibrating body is caused to vibrate by being applied to the vibrating body, the weight of the apparatus is increased.

  The objective of this invention made | formed in view of this viewpoint is providing the sound generator and sound generation system which can be comprised simply and lightweight.

The sound generator according to the present invention that achieves the above object is as follows.
A piezoelectric vibration part having a laminated piezoelectric element that expands and contracts along the lamination direction;
A permanent magnet,
In a state where the piezoelectric vibration part is pressed against the contact surface by the magnetic force of the permanent magnet, applying the sound signal to the multilayer piezoelectric element deforms the multilayer piezoelectric element to deform the piezoelectric vibration part, Based on the deformation of the piezoelectric vibration part, the contact surface is vibrated by the bending deformation of the housing that accommodates the piezoelectric vibration part to generate sound from the contact surface.

A holding portion for storing and holding the piezoelectric vibrating portion;
An end on the inner side of the sound generator in the stacking direction of the stacked piezoelectric element is fixed to the holding unit via an adhesive, and an end opposite to the end in the stacking direction of the piezoelectric vibrating unit The part may contact the contact surface .

The piezoelectric vibration section may include a covering member made of a soft plastic that transmits vibration due to deformation of the multilayer piezoelectric element to the contact surface to vibrate the contact surface.

  The sound signal may be a signal in which at least a part of a frequency component higher than a predetermined threshold is cut or attenuated.

  The sound signal may be a signal whose attenuation rate increases gradually or stepwise as the frequency becomes higher than the predetermined threshold.

  The sound signal may be a signal in which at least a part of a frequency component higher than the predetermined threshold is cut or attenuated by a filter.

A holding portion for storing and holding the piezoelectric vibrating portion;
The entire area of the surface of the multilayer piezoelectric element perpendicular to the stacking direction may protrude outward from the holding portion .

It further includes a radio unit,
The sound signal may be generated based on a signal received by the wireless unit.

A line input unit;
The sound signal may be generated based on a line input signal input to the line input unit.

  One or a plurality of the permanent magnets may be arranged in a symmetric positional relationship with respect to the contact portion of the piezoelectric vibrating portion with respect to the contact surface in a plane orthogonal to the deformation direction of the piezoelectric vibrating portion.

  The permanent magnet may be magnetized in the deformation direction of the piezoelectric vibrating portion.

  The permanent magnet may be magnetized in a direction orthogonal to the deformation direction of the piezoelectric vibrating portion.

  The contact surface may be a mounting surface on which the sound generator is mounted.

Furthermore, the sound generation system according to the present invention that achieves the above object is as follows.
One of the above sound generators,
A vibration transmission member that can be magnetically attracted to the permanent magnet,
Applying a sound signal to the multi- layer piezoelectric element in a state where the vibration transmitting member is placed on a placement surface and the piezoelectric vibrating portion is pressed against the contact surface of the vibration transmitting member by the magnetic force of the permanent magnet. in deformed it is the multilayer piezoelectric element deforms the piezoelectric vibrating unit, based on the deformation of the piezoelectric vibrating unit, wherein prefixed via the vibration transmission member by bending deformation of the housing for accommodating the piezoelectric vibrating unit The surface is vibrated to generate sound from the mounting surface.

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

It is a figure for demonstrating the sound generator which concerns on 1st Embodiment of this invention. It is a schematic perspective view of the principal part which decomposes | disassembles and shows the bottom face side of the sound generator 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 explanatory drawing of the magnetization direction of the permanent magnet of FIG. It is a functional block diagram of the principal part of the sound generator 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 the schematic for demonstrating operation | movement of the sound generator of FIG. It is a figure which shows the two adsorption | suction aspects to the contact surface of the sound generator of FIG. It is explanatory drawing of the sound generation system which concerns on 2nd Embodiment of this invention. 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 figure which shows the other example of arrangement | positioning of a permanent magnet.

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

(First embodiment)
1A and 1B are views for explaining a sound generator according to a first embodiment of the present invention, in which FIG. 1A is an external perspective view, and FIG. 1B is a bottom view. The sound generator 10 according to the present embodiment includes a housing 20, a line input unit 30, a charging DC input terminal 40, a piezoelectric vibration unit 60, and four permanent magnets 70. The housing | casing 20 consists of arbitrary solid shapes, such as a rectangular parallelepiped shape, a polygonal shape, and a cylindrical body shape. FIG. 1 illustrates a case where the housing 20 has a rectangular parallelepiped shape.

  The line input unit 30 is connected to a line output terminal of an external device via a line (wired), and inputs a sound signal (reproduced sound signal) output from the external device, and includes, for example, a monaural jack. The charging DC input terminal 40 is used to input a DC voltage for charging the power supply unit 24 (see FIG. 2), and includes a DC jack or a USB terminal. FIG. 1 illustrates the case where the charging DC input terminal 40 is a USB terminal. The line input terminal 30 and the charging DC input terminal 40 are provided on the same or different surfaces of the top surface of the housing 20 and arbitrary side surfaces. FIG. 1 illustrates the case where the line input terminal 30 and the charging DC input terminal 40 are provided on the same side surface 20 a of the housing 20.

  The piezoelectric vibrating portion 60 is provided so as to protrude from the substantially central portion of the bottom surface 20 b of the housing 20. The permanent magnets 70 are attached to the four corners of the bottom surface 20b of the housing 20 by bonding or the like.

  In the sound generator 10 according to the present embodiment, the permanent magnet 70 provided on the bottom surface 20b of the housing 20 is magnetically attracted to the contact surface (mounting surface) of the magnetic member, so that the piezoelectric vibrating portion 60 is made permanent. The contact surface is pressed by the magnetic force of the magnet 70. In this state, the piezoelectric vibration unit 60 is deformed by applying a sound signal to the piezoelectric vibration unit 60, and the contact surface is vibrated by the deformation of the piezoelectric vibration unit 60 to generate sound from the contact surface. The piezoelectric vibrating part 60 and the permanent magnet 70 will be described in detail later.

  FIG. 2 is a schematic perspective view of an essential part of the sound generator 10 of FIG. The housing 20 includes a main body case 21 and a bottom lid 22. The main body case 21 is an exterior cover of the sound generator 10 that forms the upper surface of the housing 20 and the surrounding side surface 20a. The bottom cover 22 is an exterior cover that forms the bottom surface 20 b of the housing 20. The main body case 21 incorporates, for example, an electronic circuit unit 23, a power supply unit 24, and the like. The electronic circuit unit 23 controls the overall operation of the sound generator 10, and includes a control unit, a piezoelectric element driving unit, and the like, which will be described later. The power supply unit 24 includes a secondary battery such as a lithium-ion battery, supplies required power to the electronic circuit unit 23, and is charged by a DC voltage input from the charging DC input terminal 40.

  The sound generator 10 according to the present embodiment includes a holding unit 100 that houses and holds the piezoelectric vibrating unit 60 on the bottom surface side of the housing 20. In other words, the piezoelectric vibration unit 60 is disposed at a portion facing the contact surface where the housing 20 is attracted by the permanent magnet 70. The holding unit 100 includes, for example, a slit 101 having a uniform width that extends in a substantially vertical direction of the bottom surface 20 b of the sound generator 10 and opens to the bottom surface side of the housing 20. Further, the bottom cover 22 is provided with a hole 22a through which the piezoelectric vibrating portion 60 protrudes so that the piezoelectric vibrating portion 60 can come into contact with the contact surface.

  The piezoelectric vibration unit 60 includes a piezoelectric element 61, an O-ring 62, and an insulating cap 63 that is a covering member. A piezoelectric element is an element that expands or contracts or bends according to an electromechanical coupling coefficient of a constituent material by applying an electric signal (voltage). These elements are made of, for example, ceramic or quartz. The piezoelectric element may be a unimorph, bimorph or multilayer piezoelectric element. The multilayer piezoelectric element includes a multilayer bimorph element in which bimorphs are laminated (for example, about 8 to 50 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. The number of laminated piezoelectric elements 61 and the cross-sectional area are appropriately set so that the sound pressure or sound quality of the sound generated from the contact surface with which the piezoelectric vibrating portion 60 abuts can be sufficiently secured according to the magnetic force of the permanent magnet 70. It is determined.

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

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

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

  The cap 63 is formed of a material that can reliably transmit the expansion and contraction vibration caused by the laminated piezoelectric element 61 to the contact surface, for example, hard plastic. When it is desired to suppress damage to the contact surface, 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 63 a located in the slit 101 and a projection 63 b protruding from the housing 20 in a state of being attached to the multilayer piezoelectric element 61, and located in the slit 101. An O-ring 62 is disposed on the outer periphery of the entry portion 63a.

  The O-ring 62 is made of, for example, silicone rubber. The O-ring 62 is used to move and hold the multilayer piezoelectric element 61 and at the same time makes it difficult for moisture or dust to enter the slit 101. The protrusion 63b has a hemispherical tip. Note that the tip of the protrusion 63b is not limited to a hemispherical shape, and may be any shape as long as it is capable of reliably transmitting a point contact or a surface contact with the contact surface and transmitting the expansion and contraction vibration by the stacked 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 63 b of the cap 63 protrudes from the bottom cover 22 to the outside in a state where the bottom cover 22 is attached to the main body case 21. Further, the protruding portion 63 b of the cap 63 has a facing surface 63 c that is a surface facing the bottom cover 22. As shown in FIG. 5, in a state where no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand and contract, the facing surface 63c is long from the bottom lid 22 that forms the bottom surface 20b of the housing 20. They are separated by a distance d.

  In FIG. 2, permanent magnets 70 are attached to the bottom lid 22 by adhesion or the like at the four corners on the bottom surface side of the housing 20. The permanent magnet 70 can be of any type such as a ferrite magnet or a neodymium magnet. Moreover, the thing of arbitrary shapes, such as a square shape and a column shape, can also be used for a shape. Here, a case where the permanent magnet 70 has a rectangular shape is illustrated. The permanent magnets 70 are preferably bonded to the four corners of the bottom cover 22 in a symmetric positional relationship with respect to the piezoelectric vibrating portion 60. That is, the permanent magnet 70 is mounted in a symmetric positional relationship with respect to the cap 63 of the piezoelectric vibrating portion 60 in a plane orthogonal to the deformation direction of the piezoelectric vibrating portion 60.

  In the permanent magnet 70, the magnetization direction may be the deformation direction of the piezoelectric vibrating portion 60 as shown in FIG. 6A, that is, the normal direction of the bottom cover 22, or as shown in FIG. 6B. The direction orthogonal to the deformation direction of the piezoelectric vibrating portion 60, that is, the direction parallel to the surface of the bottom cover 22 may be used. The permanent magnet 70 has such a thickness that the cap 63 of the piezoelectric vibrating portion 60 is pressed against the contact surface by the magnetic force of the permanent magnet 70 when magnetically attracted to the contact surface made of a magnetic material.

  FIG. 7 is a functional block diagram of a main part of the sound generator 10 according to the present embodiment. The sound generator 10 includes a line input unit 30, a stacked piezoelectric element 61, a radio unit 110, a piezoelectric element driving unit 120, and a control unit 130. The power supply unit 24 and the charging DC input terminal 40 are not shown. The line input unit 30, the radio unit 110, and the piezoelectric element driving unit 120 are connected to the control unit 130. The stacked piezoelectric element 61 is connected to the piezoelectric element driving unit 120.

  The wireless unit 110 receives an electromagnetic wave modulated by a reproduction sound signal, and includes a short-range wireless communication unit such as Bluetooth (registered trademark), a low-power wireless communication unit, and the like. The wireless unit 110 may be a radio receiving unit such as AM / FM or an infrared receiving unit that does not have a transmission function. The control unit 130 applies a reproduction sound signal (a voltage corresponding to a reproduction sound signal such as a sound or music containing music) to the stacked piezoelectric element 61 via the piezoelectric element driving unit 120. The reproduced sound signal may be based on an electromagnetic wave received by the wireless unit 110 or may be input from the line input unit 30.

  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 is required for equalization processing, D / A conversion processing, and the like on the digital signal from the control unit 130. 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 unit 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 laminated piezoelectric element 61 by the booster circuit 122 can be set to 1 Vpp to 500 Vpp, for example, but is not limited to this range, and the magnetic force of the permanent magnet 70 or the laminated piezoelectric element. It can be appropriately adjusted according to the performance of the element 61 and the like. 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, by attenuating or cutting the high-frequency component, power consumption can be suppressed and heat generation of the multilayer piezoelectric element 61 can be suppressed. The control unit 130 is configured by, for example, a CPU, a DSP, and the like.

  FIGS. 10A, 10B, and 10C are schematic diagrams for explaining the operation of the sound generator 10 according to the present embodiment. As shown in FIG. 10A, the sound generator 10 magnetically attracts the permanent magnet 70 to the contact surface 150 of the magnetic member with the bottom surface 20b side of the housing 20 facing downward. Thereby, the cap 63 of the piezoelectric vibrating portion 60 is pressed against the contact surface 150 by the magnetic force of the permanent magnet 70. In the state shown in FIG. 10A, no voltage is applied to the multilayer piezoelectric element 61, so that the multilayer piezoelectric element 61 does not expand or contract.

  In this state, when the multilayer piezoelectric element 61 of the piezoelectric vibration unit 60 is driven by the reproduced sound signal, the multilayer piezoelectric element 61 has the cap 63 as the contact surface as shown in FIGS. Without being separated from 150, it expands and contracts according to the reproduced sound signal. The difference between the length of the multilayer piezoelectric element 61 when it is most expanded and the length when it is most contracted is, for example, 0.05 μm to 100 μm. At this time, the permanent magnet 70 maintains the attracted state without being separated from the contact surface 150. Therefore, the sound generator 10 bends in the expansion / contraction direction according to the vibration of the multilayer piezoelectric element 61. As a result, the expansion and contraction vibration of the multilayer piezoelectric element 61 is transmitted to the contact surface 150 through the cap 63 and the contact surface 150 vibrates, and the contact surface 150 functions as a vibration speaker to generate sound from the contact surface 150. If the difference between the length when the laminated piezoelectric element 61 is most stretched and the length when it is most contracted is less than 0.05 μm, the contact surface 150 may not be vibrated properly, whereas if it exceeds 100 μm. There is a risk that the sound generator 10 may rattle due to increased vibration due to frequency. In FIGS. 10B and 10C, the bending of the sound generator 10 is exaggerated. 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, the distance d between the bottom surface 20b and the facing surface 63c of the cap 63 shown in FIG. 5 is the most contracted 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 that the amount of displacement is longer than the amount of displacement when it is in a state. This makes it difficult for the bottom surface 20b of the housing 20 and the cap 63 to come into contact with each other even when the multilayer piezoelectric element 61 is contracted most (the state shown in FIG. 10C). Therefore, it becomes difficult for the cap 63 to fall off the piezoelectric element 61.

  The length of the stacked piezoelectric element 61 in the stacking direction, the size of the cap 63, and the like are appropriately determined so as to satisfy the above conditions.

  According to the sound generator 10 according to the present embodiment, since the piezoelectric element is used as a vibration source, the number of parts can be reduced and the number of parts can be reduced as compared with a conventional vibration generator having a dynamic speaker structure. It can be simply configured. 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 laminated piezoelectric element 61 is pressed against the contact surface 150 via the cap 63, the laminated piezoelectric element 61 can be prevented from being damaged.

  In addition, since the sound generator 10 according to the present embodiment can mainly transmit the vibration of the multilayer piezoelectric element 61 directly to the contact surface 150, the related art transmits the vibration of the piezoelectric element to another elastic body. Unlike the case, 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 sound generator 10 according to the present embodiment may have rigidity (bending strength) that does not cause bending deformation due to deformation of the multilayer piezoelectric element 61.

  In addition, since the sound generator 10 according to the present embodiment presses the piezoelectric vibrating portion 60 against the contact surface 150 by the magnetic force of the permanent magnet 70, the cap 63 is attached to the contact surface 150 without providing a weight on the sound generator 10. The expansion and contraction vibration of the piezoelectric vibration part 60 can be efficiently transmitted to the contact surface 150. Therefore, the weight of the sound generator 10 can be reduced to, for example, about 100 g. Moreover, since the sound generator 10 is attracted to the contact surface by a magnetic force, the contact surface 150 is not limited to a flat surface as shown in FIG. As shown in FIG. 11B, the contact surface 150 can be adsorbed even when it is a vertical surface, and can also be adsorbed when it is an inclined surface. Therefore, in a room, for example, it can be used by being adsorbed to a magnetic sink of a kitchen, a door or side of a refrigerator, or the like. In addition, it can be used by being adsorbed to a vehicle body such as a hood of a parked car, for example, and convenience and versatility can be improved.

  Here, the attracting force by the permanent magnet 70 is set so that vibration can be reliably transmitted to the contact surface 150 even when attracted to the vertical contact surface 150 as shown in FIG. For example, when the weight of the sound generator 10 is 100 g, when the adsorption rate to the contact surface 150 is 75% and the vertical slip is 25%, a permanent magnet 70 having an adsorption force of 0.533 kgf or more may be attached. . Therefore, for example, when a neodymium magnet is used, it is preferable to attach a cube having a size of length × width × thickness of 4 mm × 4 mm × 4 mm, for example. In this case, an adsorption force of 0.628 kgf is obtained.

(Second Embodiment)
FIG. 12 is an explanatory diagram of a sound generation system according to the second embodiment of the present invention. The sound generation system according to the present embodiment is a plate-shaped vibration transmission member that includes the sound generator 10 described in the first embodiment and a magnetic member that can be magnetically attracted to the permanent magnet 70 of the sound generator 10. 160. That is, since the sound generator 10 is used by being magnetically attracted to the contact surface, the member constituting the contact surface needs to have magnetism. However, the mounting surface 170 of the sound generator 10 desired by the user may be made of a nonmagnetic member.

  The sound generation system according to the present embodiment places the sound generator 10 on the placement surface 170 and places the placement surface 170 even when the placement surface 170 desired by the user is made of a non-magnetic member. The sound can be generated from. Therefore, in the sound generation system according to the present embodiment, the sound generator 10 is placed on the placement surface 170 via the vibration transmission member 160 by adsorbing the sound generator 10 to the vibration transmission member 160. Thereby, the vibration of the piezoelectric vibrating portion 60 of the sound generator 10 is transmitted to the mounting surface 170 via the vibration transmitting member 160 to generate sound from the mounting surface 170.

  The vibration transmission member 160 is made of a known magnetic material such as iron or silicon steel. The vibration transmission member 160 may or may not be coated with a nonmagnetic coating. The vibration transmitting member 160 can have any shape, size, and thickness as long as all the permanent magnets 70 can be attracted and the vibration of the piezoelectric vibration unit 60 can be reliably transmitted to the mounting surface 170. It may be visually apparent that the shape and size are substantially the same as the bottom surface 20b of the housing 20. The vibration transmitting member 160 may be brought into surface contact with the mounting surface 170 with the surface on the side in contact with the mounting surface 170 as a plane, or three or more on the surface in contact with the mounting surface 170. These protrusions may be formed to make point contact with the mounting surface 170.

  According to the sound generation system according to the present embodiment, the sound generator 10 is placed on the placement surface 170 via the vibration transmission member 160 even when the placement surface 170 desired by the user is made of a non-magnetic member. By doing so, a sound can be generated from the mounting surface 170.

  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 part 60 to the holding part 100 is not limited to the structure shown in FIG. For example, as shown in FIGS. 13A to 13C, the piezoelectric vibration unit 60 may be held by the holding unit 100. A holding unit 100 shown in FIG. 13A includes a wide slit 101a that opens to the bottom 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. Thus, if the piezoelectric vibration part 60 is hold | maintained at the holding | maintenance part 100, the sound generator 10 can be waterproofed more reliably, without using waterproof packings, such as an O-ring. In addition, by covering the portion protruding from the side surface 20a of the multilayer piezoelectric element 61 with an insulating cap, the multilayer piezoelectric element 61 can be reliably insulated.

  The holding unit 100 shown in FIG. 13B includes a tapered slit 101c that expands toward the bottom 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 of FIG. 13A 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. 13C has a slit 101 having a uniform width as in the above embodiment, but the end face on one end side of the laminated piezoelectric element 61 is interposed through the adhesive 102. It is fixed to the slit 101. Further, a waterproof O-ring 62 is disposed at an appropriate position of the multilayer piezoelectric element 61 in the slit 101. Such a holding mode of the laminated piezoelectric element 61 is particularly suitable when the laminated piezoelectric element 61 has a lead wire connecting portion formed on a side electrode as shown in FIG. Etc. are advantageous.

  Further, in the above embodiment and the modified examples of FIGS. 13A to 13C, the piezoelectric vibrating portion 60 omits the cap 63, and the tip surface of the multilayer piezoelectric element 61 is formed directly or made of an insulating member or the like. You may 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. 14 is a diagram showing a schematic configuration of a main part when a bimorph is used. The bimorph 65 has a long rectangular shape, one surface 65 a is exposed on the side surface 20 a of the housing 20, and both long ends are held by the holding unit 100. The holding unit 100 has an opening 101e that holds the bimorph 65, and the inner surface of the opening 101e on the back surface 65b side of the bimorph 65 is curved. According to this configuration, when the housing 20 is magnetically attracted to the contact surface, the bimorph 65 presses the contact surface with a magnetic force. In this state, when the bimorph 65 is driven by a reproduction sound signal, the bimorph 65 is bent (curved) and vibrated. As a result, the vibration of the bimorph 65 is transmitted to the contact surface, and the contact surface functions as a vibration speaker, and a reproduction sound is generated from the contact surface. Note that a coating layer such as polyurethane may be formed on the surface 65 a of the bimorph 65. Moreover, the bimorph 65 may be configured to directly press the contact surface, or a relay member may be joined to the surface 65a of the bimorph 65 and the contact surface may be pressed via the relay member.

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

  Further, the number of permanent magnets for attracting the housing 20 is not limited to four, but may be an arbitrary number. For example, as shown in FIG. 15A, two rod-like permanent magnets 71 may be attached at positions symmetrical with respect to the piezoelectric vibrating portion 60 on both sides of the bottom lid 22. In this case, as described in the first embodiment, when the sound generator 10 has a weight of 100 g and is attracted to a vertical contact surface, in order to obtain an adsorption force of 0.533 kgf or more, for example, a ferrite magnet Is used, it is preferable to attach a rectangular column shape with dimensions of length × width × thickness of 22 mm × 22 mm × 5 mm. In this case, an adsorption force of 0.535 kgf is obtained. Further, as shown in FIG. 15B, a single permanent magnet 72 having a square outer shape and a hollow shape may be mounted so that the piezoelectric vibrating portion 60 is located at the center of the hollow. As shown in (c), one ring-shaped permanent magnet 73 may be mounted so that the piezoelectric vibrating portion 60 is located in the hollow center portion. Alternatively, three permanent magnets may be attached to the bottom surface 20b of the housing 20 in a symmetrical positional relationship with respect to the piezoelectric vibrating portion 60 so that the sound generator 10 is attracted to the contact surface at three points.

  Further, the permanent magnet may be mounted inside the bottom cover 22, that is, inside the casing 20 without being exposed and mounted on the bottom surface 20 b of the casing 20. In this case, a nonmagnetic or magnetic spacer having an appropriate thickness may be provided on the bottom surface 20b in accordance with the amount of protrusion of the piezoelectric vibrating portion 60. The sound generator 10 is not limited to a permanent magnet, and is held on the contact surface by a known peelable adhesive member such as a hook-and-loop fastener so as to transmit the vibration of the piezoelectric vibrating portion 60 to the contact surface. Also good.

  In the description of the above embodiment, it has been described that a cap is inserted into the other end of the multilayer piezoelectric element, but the present invention is not limited to such a case. For example, such a cap may not be used at the other end of the multilayer piezoelectric element.

  Further, in the description of the above embodiment, the laminated piezoelectric element is fixed to the slit of the holding portion of the housing via an adhesive (for example, epoxy resin). It is not limited. For example, instead of the adhesive, a method may be adopted in which, for example, a slit is formed in an elastic body such as silicon rubber, and the element is pushed in and fixed.

  In addition, the above-described embodiments, modifications, and modifications can be appropriately combined as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Sound generator 20 Case 20a Side surface 20b Bottom surface 30 Line input part 40 DC input terminal for charge 60 Piezoelectric vibration part 61 Multilayer piezoelectric element (piezoelectric element)
62 O-ring 63 Cap 70 Permanent magnet 100 Holding part 101 Slit 102 Adhesive 110 Radio part 120 Piezoelectric element drive part 121 Signal processing circuit 122 Booster circuit 123 Low pass filter (LPF)
130 control unit 150 contact surface 160 vibration transmission member 170 mounting surface

Claims (14)

A piezoelectric vibration part having a laminated piezoelectric element that expands and contracts along the lamination direction;
A permanent magnet,
In a state where the piezoelectric vibration part is pressed against the contact surface by the magnetic force of the permanent magnet, applying the sound signal to the multilayer piezoelectric element deforms the multilayer piezoelectric element to deform the piezoelectric vibration part, Based on the deformation of the piezoelectric vibration part, the contact surface is vibrated by a bending deformation of a housing that accommodates the piezoelectric vibration part, and a sound is generated from the contact surface.
Sound generator. A holding portion for storing and holding the piezoelectric vibrating portion;
An end on the inner side of the sound generator in the stacking direction of the stacked piezoelectric element is fixed to the holding unit via an adhesive, and an end opposite to the end in the stacking direction of the piezoelectric vibrating unit parts are you in contact with the contact surface,
The sound generator according to claim 1. The piezoelectric vibration unit includes a covering member made of soft plastic that transmits vibration due to deformation of the multilayer piezoelectric element to the contact surface to vibrate the contact surface.
The sound generator according to claim 1. The sound signal is a signal in which at least a part of a frequency component higher than a predetermined threshold is cut or attenuated.
The sound generator according to claim 1. The sound signal is a signal whose attenuation rate increases gradually or stepwise as the frequency becomes higher than the predetermined threshold.
The sound generator according to claim 4. The sound signal is a signal in which at least part of a frequency component higher than the predetermined threshold is cut or attenuated by a filter.
The sound generator according to claim 4. A holding portion for storing and holding the piezoelectric vibrating portion;
The whole area of the surface perpendicular to the stacking direction of the stacked piezoelectric element protrudes from the holding portion,
The sound generator according to claim 1. It further includes a radio unit,
The sound signal is generated based on a reception signal by the wireless unit.
The sound generator according to claim 1. A line input unit;
The sound signal is generated based on a line input signal input to the line input unit.
The sound generator according to claim 1. One or a plurality of the permanent magnets are arranged in a symmetric positional relationship with respect to the contact portion of the piezoelectric vibrating portion with respect to the contact surface in a plane orthogonal to the deformation direction of the piezoelectric vibrating portion.
The sound generator according to claim 1. The permanent magnet is magnetized in the deformation direction of the piezoelectric vibrating part,
The sound generator according to claim 1. The permanent magnet is magnetized in a direction orthogonal to the deformation direction of the piezoelectric vibration part,
The sound generator according to claim 1. The contact surface is a mounting surface on which the sound generator is mounted.
The sound generator according to claim 1. The sound generator according to any one of claims 1 to 12,
A vibration transmission member that can be magnetically attracted to the permanent magnet,
Applying a sound signal to the multi-layer piezoelectric element in a state where the vibration transmitting member is placed on a placement surface and the piezoelectric vibrating portion is pressed against the contact surface of the vibration transmitting member by the magnetic force of the permanent magnet. The multilayer piezoelectric element is deformed to deform the piezoelectric vibration part, and the piezoelectric vibration part is deformed to deform the piezoelectric vibration part based on the deformation of the housing that houses the piezoelectric vibration part. Vibrating the surface to generate sound from the mounting surface,
Sound generation system.

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