JP2014072711A - Acoustic generator, acoustic generation device and electronic apparatus - Google Patents

Abstract

A sound generator, a sound generator, and an electronic device capable of reducing a difference between a resonance peak and a dip in a frequency characteristic of sound pressure to suppress a frequency fluctuation of sound pressure as much as possible to improve sound quality. I will provide a.
An acoustic generator according to an embodiment includes a thin plate-like vibrating body and an exciter provided on the vibrating body. The vibrating body includes a first region on a surface where the exciter is provided, and a second region in which the interval between the nodes of the standing wave of vibration is different from the interval between the nodes of the standing wave of vibration in the first region. Have
[Selection] Figure 2

Description

  Embodiments of the disclosure relate to a sound generator, a sound generation device, and an electronic apparatus.

  Conventionally, it is known that an acoustic generator typified by a piezoelectric speaker can be used as a small and thin speaker. Such a sound generator can be used as a speaker incorporated in an electronic device such as a mobile phone or a thin television.

  As an acoustic generator, for example, there is one including a vibrating body and a piezoelectric vibrating element provided on the vibrating body (see, for example, Patent Document 1). This is a configuration in which a vibrating body is vibrated by a piezoelectric vibration element, and a sound is generated using a resonance phenomenon of the vibrating body.

Japanese Patent Laid-Open No. 2004-23436

  However, in the configuration in which sound pressure is generated by resonance of the vibrating body itself as in the acoustic generator described above, the sound pressure is reduced due to the difference between the resonance peak and the dip (valley between resonance peaks) in the frequency characteristics of the sound pressure. There was a risk of frequency fluctuations. And this may hinder improvement in sound quality.

  One aspect of the embodiment has been made in view of the above, and reduces the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure to suppress the frequency fluctuation of the sound pressure as much as possible, thereby improving the sound quality. An object is to provide a sound generator, a sound generator, and an electronic device that can be improved.

  An acoustic generator according to an aspect of an embodiment includes a thin plate-like vibrating body and an exciter provided on the vibrating body. The vibrator is provided with a second region in which the distance between the first region and the node of the standing wave of vibration is different from the distance of the node of the standing wave of vibration in the first region on the surface where the exciter is provided. And having a region.

  According to the acoustic generator of one aspect of the embodiment, it is possible to improve the sound quality by reducing the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure and suppressing the frequency fluctuation of the sound pressure as much as possible. .

FIG. 1A is a schematic plan view of the sound generator according to the first embodiment. 1B is a cross-sectional view taken along line A-A ′ of FIG. 1A. FIG. 2 is an explanatory diagram showing a standing wave of vibration generated in the vibrating body of the acoustic generator shown in FIG. FIG. 3 is a schematic plan view showing an acoustic generator according to a modification of the first embodiment. FIG. 4 is a schematic plan view showing an acoustic generator according to another modification of the first embodiment. FIG. 5 is a cross-sectional view taken along line A-A ′ of FIG. 1A, showing an acoustic generator according to another modification example of the first embodiment. FIG. 6 is a block diagram of the sound generator. FIG. 7 is a block diagram of an electronic device. FIG. 8 is a schematic plan view showing an acoustic generator according to the second embodiment. FIG. 9 is a schematic plan view showing another arrangement example of the first and second regions.

  Hereinafter, embodiments of a sound generator, a sound generator, and an electronic device disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

(First embodiment)
FIG. 1A is a schematic plan view of the sound generator 1 according to the first embodiment viewed from a direction perpendicular to the main surface of the vibrating body 10, and FIG. 1B is a cross-sectional view taken along the line AA ′ in FIG. 1A. is there. For ease of explanation, FIGS. 1A and 1B illustrate a three-dimensional orthogonal coordinate system including a Z-axis having a vertically upward direction as a positive direction and a vertically downward direction as a negative direction. Such an orthogonal coordinate system may also be shown in other drawings used in the following description. Further, in FIG. 1B, for easy understanding, the sound generator 1 is expanded in the vertical direction (Z-axis direction) and deformed.

  As shown in FIGS. 1A and 1B, the acoustic generator 1 according to the embodiment includes a vibrating body 10, a plurality of piezoelectric vibrating elements 20, and a frame body 30. Such an acoustic generator 1 is called a so-called piezoelectric speaker, and generates a sound pressure using a resonance phenomenon of the vibrating body 10 itself.

  As shown in FIG. 1A, in the present embodiment, the case where the acoustic generator 1 includes two piezoelectric vibration elements 20 is illustrated, but the number is not limited to this, and the number is one or three. It may be more than one. In the present embodiment, the description will be given assuming that the two piezoelectric vibration elements 20 have substantially the same shape.

  The vibrating body 10 can be formed using various materials such as resin, metal, and paper. For example, the thin plate-like vibrating body 10 can be formed of a resin film such as polyethylene, polyimide, or polypropylene having a thickness of about 10 to 200 μm. Since the resin film is a material having a lower elastic modulus and mechanical Q value than a metal plate or the like, the vibrating body 10 is made of a resin film to bend and vibrate the vibrating body 10 with a large amplitude so that the sound pressure is reduced. It is possible to reduce the difference between the resonance peak and the dip by widening the width of the resonance peak and reducing the height in the frequency characteristics.

  The piezoelectric vibration element 20 is an exciter that excites the vibrating body 10 by vibrating under application of a voltage. For example, the piezoelectric vibration element 20 is a bimorph multilayer piezoelectric vibration element. Thus, since the exciter is the piezoelectric vibration element 20, it is possible to make it thinner as compared with an electromagnetic exciter using a coil and a magnet, and thus the acoustic generator 1 is made thin. be able to. In addition, since the piezoelectric vibration element 20 is a bimorph type that bends and vibrates by itself (one element), the piezoelectric vibration element 20 is suitable for vibrating the thin plate-like vibrating body 10. Sound pressure can be generated.

  Specifically, as shown in FIG. 1B, the piezoelectric vibration element 20 includes a laminate 21, surface electrode layers 22 and 23 formed on the top and bottom surfaces of the laminate 21, and an internal electrode layer 24 of the laminate 21. And external electrodes 25 and 26 formed on the side surface where the end face is exposed. Then, lead terminals 27 a and 27 b are connected to the external electrodes 25 and 26.

  The multilayer body 21 is formed by alternately laminating four piezoelectric layers 28a, 28b, 28c, 28d made of ceramics and three internal electrode layers 24, for example. The piezoelectric vibration element 20 has a rectangular main surface on the upper surface side and the lower surface side, and the piezoelectric layers 28a and 28b and the piezoelectric layers 28c and 28d are alternately polarized in the thickness direction (Z-axis direction). Has been.

  Therefore, when a voltage is applied to the piezoelectric vibration element 20 via the lead terminals 27a and 27b, for example, the lower surface side of the piezoelectric vibration element 20, in other words, the piezoelectric layers 28c and 28d on the vibration body 10 side contract, while the upper surface The piezoelectric layers 28a and 28b on the side are deformed so as to extend. As described above, the piezoelectric layers 28a and 28b on the upper surface side of the piezoelectric vibration element 20 and the piezoelectric layers 28c and 28d on the lower surface side exhibit opposite expansion and contraction behavior, and as a result, the piezoelectric vibration element 20 is bent bimorph-shaped. By vibrating, a certain vibration can be given to the vibrating body 10 to generate a sound.

  Here, as materials constituting the piezoelectric layers 28a, 28b, 28c, and 28d, lead-free piezoelectric materials such as lead zirconate titanate (PZT), Bi layered compounds, and tungsten bronze structure compounds are used. Conventionally used piezoelectric ceramics can be used.

  The material of the internal electrode layer 24 preferably contains a metal component made of silver and palladium and a material component constituting the piezoelectric layers 28a, 28b, 28c, 28d. When the internal electrode layer 24 contains the ceramic component constituting the piezoelectric layers 28a, 28b, 28c, 28d, the difference in thermal expansion between the piezoelectric layers 28a, 28b, 28c, 28d and the internal electrode layers 24, 24, 24. Thus, it is possible to obtain the piezoelectric vibration element 20 in which the stress due to the above is reduced.

  Further, as the wiring connected to the lead terminals 27a and 27b, in order to reduce the height of the piezoelectric vibration element 20, it is preferable to use a flexible wiring in which a metal foil such as copper or aluminum is sandwiched between resin films.

  The piezoelectric vibration element 20 configured as described above is provided on the vibrating body 10. Specifically, the piezoelectric vibration element 20 is bonded to the vibration surface 10a of the vibrating body 10 via a bonding portion 40 formed of an adhesive. The thickness of the joint portion 40 between the piezoelectric vibration element 20 and the vibrating body 10 is relatively thin, for example, 20 μm or less. Thus, when the thickness of the joint portion 40 is 20 μm or less, the vibration of the stacked body 21 can be easily transmitted to the vibrating body 10.

  As an adhesive for forming the joint portion 40, for example, a known material such as an epoxy resin, a silicon resin, or a polyester resin can be used, but the adhesive is not limited thereto. In addition, as a method for curing the resin used for the adhesive, any method such as thermosetting, photocuring, and anaerobic curing may be used.

  The frame 30 holds the vibrating body 10 and plays a role of forming a stationary end of a vibration standing wave to be described later. For example, although illustration is omitted, a structure in which the vibrating body 10 is pasted on a circular or elliptical ring-shaped frame 30 is used, and furthermore, as shown in FIG. For example, the frame body 30 is configured by vertically joining a rectangular upper frame member 30 a and a lower frame member 30 b. And the outer peripheral part of the vibrating body 10 is pinched | interposed between the upper frame member 30a and the lower frame member 30b, and it fixes in the state which provided predetermined tension. Therefore, the acoustic generator 1 including the vibrating body 10 with less deformation such as deflection even when used for a long time is obtained.

  A portion of the vibrating body 10 located inside the frame body 30, that is, a portion of the vibrating body 10 that is not sandwiched between the frame bodies 30 and can vibrate freely is defined as a vibrating surface 10 a. Therefore, the vibration surface 10 a of the vibration body 10 provided with the piezoelectric vibration element 20 is a polygonal shape, specifically, for example, a substantially rectangular shape in the frame of the frame body 30.

  The thickness and material of the frame 30 are not particularly limited, but in the present embodiment, for example, a stainless steel material having a thickness of 100 to 1000 μm is used because of its excellent mechanical strength and corrosion resistance. Use.

  FIG. 2 is an explanatory view showing a standing wave of vibration generated in the vibrating body 10 of the acoustic generator 1, and is a cross-sectional view taken along the line A-A 'similar to FIG. 1B. In FIG. 2, the acoustic generator 1 is not expanded and deformed in the vertical direction (Z-axis direction) as shown in FIG. 1B, but the piezoelectric vibration element 20 and the like are shown in a simplified manner.

  In the sound generator 1, for example, components such as the piezoelectric vibration element 20 are arranged on the vibrating body 10 so as to be substantially vertically and substantially symmetrical in FIG. 1A so that the center of gravity is near the center. In this case, the node interval (wavelength) La of the standing wave W ′ of the vibration of the vibrating body 10 is substantially constant over the entire area of the vibrating body 10, as indicated by an imaginary line in FIG. However, when the node interval La of the vibration standing wave W ′ becomes substantially constant, strong resonance occurs at a specific frequency. Therefore, in the frequency characteristics of sound pressure, the resonance peak and dip (valley between resonance peaks) There was a problem that the difference became large.

  Therefore, in the present embodiment, the vibrating body 10 has the first region 11 and the node distance L2 between the vibration standing wave W on the surface where the piezoelectric vibration element 20 is provided, that is, the vibration surface 10a. 11 and a second region 12 different from the node interval L1 of the standing wave W of vibration. This makes it difficult for strong resonance to occur at a specific frequency, so that the difference between the resonance peak and the dip in the frequency characteristic of sound pressure can be reduced. The first and second regions 11 and 12 will be described later.

  Continuing the description of the acoustic generator 1, in the acoustic generator 1, as shown in FIG. 1B, the piezoelectric vibration element 20 and the vibration surface 10 a of the vibrating body 10 are covered with a covering portion 50 made of resin. Specifically, the covering portion 50 is configured to cover the piezoelectric vibration element 20 and the like by pouring resin into the frame of the upper frame member 30a of the frame body 30 and curing the resin. In FIG. 1A, for easy understanding, the covering portion 50 is shown through, and the vibration surface 10 a of the piezoelectric vibration element 20 and the vibrating body 10 covered by the covering portion 50 are shown.

  The resin forming the covering portion 50 is, for example, an epoxy resin, an acrylic resin, a silicon resin, or rubber, but these are examples and are not limited. Thus, by covering the piezoelectric vibration element 20 with the covering portion 50, an appropriate damping effect can be induced, and the resonance phenomenon can be suppressed and the difference between the resonance peak and the dip can be further reduced. preferable. Furthermore, the piezoelectric vibration element 20 can be protected from the external environment.

  In the acoustic generator 1 according to the present embodiment, the entire vibration surface 10a of the vibrating body 10 is covered with the covering portion 50, but it is not necessary to cover all of them. That is, in the acoustic generator 1, the piezoelectric vibration element 20 and at least a part of the vibration surface 10 a of the vibrating body 10 provided with the piezoelectric vibration element 20 may be covered with the covering portion 50. In addition, as a method for curing the resin used for the covering portion 50, any method such as thermosetting, photocuring, and moisture curing may be used.

  Here, the first region 11 and the second region 12 described above will be described in detail. As shown in FIG. 1A, the first region 11 and the second region 12 are arranged on the vibration surface 10a of the vibrating body 10 on which the piezoelectric vibration element 20 is provided, with the piezoelectric vibration element 20 interposed therebetween. For example, the piezoelectric vibration element 20 is disposed so as to straddle the first region 11 and the second region 12. The first region 11 and the second region 12 are arranged side by side (in parallel) in the longitudinal direction (Y-axis direction) of the vibration surface 10a on which the piezoelectric vibration element 20 of the vibrating body 10 is provided. Specifically, the first region 11 and the second region 12 are substantially parallel to the line 13 that is substantially orthogonal to the longitudinal direction on the vibration surface 10a, in other words, substantially parallel to the short side direction (X-axis direction) on the vibration surface 10a. It is defined by a line 13. The line 13 is, for example, a line that divides the area of the vibration surface 10a into substantially right and left in the plan view of FIG. 1A.

  In FIG. 1A and the like, the position of the line 13 that divides the first region 11 and the second region 12 is illustrated, but the position of the line 13 is not limited to this, and the first and second regions are not limited thereto. Any position may be used as long as the vibration surface 10a is partitioned so that the regions 11 and 12 are aligned in the longitudinal direction. Further, although the vibration surface 10a is divided into two regions, the first region 11 and the second region 12, it may be divided into three or more regions. Further, although the line 13 is shown as a straight line, it may be a curved line or the like. Further, in FIG. 1A and the like, the line 13 is shown by a two-dot chain line for easy understanding, but the line is not actually drawn on the vibration surface 10a.

  The sound generator 1 further includes a damping material 60, and the damping material 60 is attached to the surface of the covering portion 50 corresponding to the first region 11 of the vibrating body 10 described above. Hereinafter, in detail, the damping material 60 is formed in a substantially rectangular parallelepiped shape, for example. However, the shape of the damping material 60 illustrated in FIG. 1A and the like is an example, and is not limited to a substantially rectangular parallelepiped shape.

  As shown in FIG. 1B, the damping material 60 is attached to the surface of the covering portion 50 via an adhesive 61, and is integrated with the vibrating body 10, the piezoelectric vibration element 20, and the covering portion 50. In other words, the covering portion 50 is disposed between the vibrating body 10 and the damping material 60, and is joined so that the vibrating body 10, the piezoelectric vibration element 20, the covering portion 50, and the damping material 60 are integrated.

  As the adhesive 61, for example, a known material such as an epoxy resin, a silicon resin, or a polyester resin can be used, but is not limited thereto. The curing method of the adhesive 61 may be any method such as thermal curing, photocuring, and moisture curing.

  The damping material 60 only needs to have mechanical loss, but is desirably a member having a high mechanical loss factor, in other words, a low mechanical quality factor (so-called mechanical Q). Such a damping material 60 can be formed using various elastic bodies, for example, but since it is desirable that it is soft and easily deformed, it can be suitably formed using a rubber material such as urethane rubber. In particular, a porous rubber material such as urethane foam can be suitably used.

  Further, as shown in FIG. 1A, the damping material 60 is a surface of the covering portion 50 corresponding to the first region 11 of the vibrating body 10, and is along the short direction (X-axis direction) of the frame body 30. One is arranged. In addition, although arrangement | positioning of the damping material 60 was shown to FIG. 1A etc., this is an example and does not limit an arrangement | positioning location.

  Thus, in the sound generator 1 according to the present embodiment, the arrangement of the damping material 60 is made different between the first region 11 and the second region 12. Specifically, for example, the damping material 60 is disposed on the surface of the covering portion 50 corresponding to the first region 11, while the damping material 60 is not disposed on the surface of the covering portion 50 corresponding to the second region 12. To. That is, in the plan view of the vibrating body 10, the damping material 60 is disposed so as to be asymmetrical with respect to the line 13 so that the center of gravity is shifted from the vicinity of the center.

  As described above, when the center of gravity of the acoustic generator 1 is shifted from the vicinity of the center and the load acting on the vibrating body 10 is different between the first region 11 and the second region 12, the vibration generated in the vibrating body 10 is determined. As shown by a solid line in FIG. 2, the standing wave W includes a node interval L1 of the vibration standing wave W in the first region 11 and a node interval L2 of the vibration standing wave W in the second region 12. Will be different. Specifically, for example, the node interval L1 of the vibration standing wave W in the first region 11 is larger than the node interval L2 of the vibration standing wave W in the second region 12.

  As described above, the vibrating body 10 has the first region 11 and the second region 12 in which the node distance of the vibration standing wave W is different, and these are arranged side by side in the longitudinal direction of the vibration surface 10a. As a result, it is difficult for strong resonance to occur at a specific frequency, and as a result, in the frequency characteristics of sound pressure, the difference between the resonance peak and the dip is reduced to suppress the frequency variation of the sound pressure as much as possible. Sound quality can be improved.

  Further, since the first region 11 and the second region 12 are arranged so as to sandwich the piezoelectric vibration element 20, the vibrating body 10 vibrates at different resonance frequencies with the piezoelectric vibration element 20 interposed therebetween. The width of the resonance peak of the audio signal generated from the sound generator 1 can be widened, and the difference between the resonance peak and the dip can be further reduced. Further, even if the frequency of the wave reflected from the vibrating body 10 to the piezoelectric vibrating element 20 is different, the piezoelectric vibrating element 20 between the first region 11 and the second region 12 shields the reflected wave. Therefore, a wave does not propagate from the other region to each region, and an audio signal can be generated stably at a specific resonance frequency.

  Further, since the arrangement of the damping material 60 is made different between the first region 11 and the second region 12, the node interval L1 of the standing wave W of the vibration in the first region 11 and the second The distance L2 between the nodes of the standing wave W of the vibration in the region 12 can be easily made different.

  In addition, by using the damping material 60, the region of the vibration surface 10 a of the vibrating body 10 corresponding to the arrangement location of the damping material 60 (that is, the first region 11) is vibrated by the damping material 60 via the covering portion 50. Loss is received, so that the resonance phenomenon is suppressed. Therefore, the resonance peak can be lowered in the frequency characteristic of the sound pressure, and the difference between the resonance peak and the dip can be further reduced.

  In the acoustic generator 1, since the damping material 60 is disposed on the covering portion 50 that covers the vibrating body 10, materials having different acoustic impedances overlap each other. Therefore, the attenuation of the resonance peak can be increased at the interface between the covering portion 50 and the damping material 60, and the peak of the sound pressure at the resonance frequency of the vibrating body 10 can be lowered more efficiently.

  In addition, in FIG. 1A etc., the one damping material 60 is illustrated, However, The number is not limited. For example, a plurality of damping materials 60 may be provided, and in this case, the number of arrangements may be different between the first region 11 side and the second region 12 side. Further, for example, the number of damping materials 60 may be the same on the first region 11 side and the second region 12 side. In this case, as shown in FIG. The first region 11 side and the second region 12 side may be asymmetric with respect to the line 13. In short, it is only necessary that the damping material 60 is disposed so as to be asymmetrical with respect to the line 13 in plan view.

  As described above, in the acoustic generator 1, the vibrating body 10 has the first region 11 and the distance L2 between the nodes of the vibration standing wave W on the surface where the piezoelectric vibration element 20 is provided. Since the second region 12 is different from the node interval L1 of the vibration standing wave W in the region 11, the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure is reduced. The frequency variation of the sound pressure can be suppressed as much as possible, and the sound quality can be improved.

  In the above description, the example in which the damping material 60 is used to make the node intervals L1 and L2 of the vibration standing wave W different is described, but the present invention is not limited to this. For example, as shown in FIG. 4, the piezoelectric vibration element 20 arranged near the center of the vibrating body 10 is shifted to the first region 11 side, whereby the node intervals L1 and L2 of the standing wave W of vibration are obtained. You may make it differ. That is, by shifting the piezoelectric vibration element 20 toward the first region 11, the load acting on the vibrating body 10 can be made different between the first region 11 and the second region 12. The intervals L1 and L2 of the nodes of the standing wave W can be made different.

  Further, as shown in FIG. 5, the distance between the nodes of the standing wave W of vibration can also be obtained by making the thickness in the Z-axis direction of the covering portion 50 different between the first region 11 side and the second region 12 side. L1 and L2 can be made different. That is, for example, by increasing the thickness in the Z-axis direction of the covering portion 50 on the first region 11 side as compared with that on the second region 12 side, the load acting on the vibrating body 10 is increased to the first region. 11 and the second region 12 can be made different, so that the node intervals L1 and L2 of the standing wave W of vibration can be made different.

  As shown in FIG. 6, the sound generator 2 can be configured by housing the sound generator 1 having the above-described configuration in a resonance box 200. The resonance box 200 is a housing that houses the sound generator 1, and resonates the sound emitted from the sound generator 1 and radiates it as sound waves from the housing surface. Such a sound generator 2 can be used alone as a speaker, and can be suitably incorporated into various electronic devices 3, for example.

  As described above, since the difference between the resonance peak and the dip in the frequency characteristic of sound pressure, which is disadvantageous in the piezoelectric speaker, can be reduced, the sound generator 1 according to the present embodiment can be used for a mobile phone or a thin television. Alternatively, it can be suitably incorporated into the electronic device 3 such as a tablet terminal.

  Note that the electronic device 3 to which the sound generator 1 can be incorporated is not limited to the above-described mobile phone, flat-screen TV, tablet terminal, and the like. Conventionally, home appliances that have not been focused on sound quality are also included.

  Here, the electronic device 3 including the above-described sound generator 1 will be briefly described with reference to FIG. FIG. 7 is a block diagram of the electronic device 3. The electronic device 3 includes the acoustic generator 1 described above, an electronic circuit connected to the acoustic generator 1, and a housing 300 that houses the acoustic generator 1 and the electronic circuit.

  Specifically, as illustrated in FIG. 7, the electronic device 3 accommodates an electronic circuit including a control circuit 301, a signal processing circuit 302, a wireless circuit 303 as an input device, an antenna 304, and these. And a housing 300. Although a wireless input device is shown in FIG. 7, it can be provided as a signal input by normal electric wiring.

  In addition, description was abbreviate | omitted here about the other electronic members (for example, devices and circuits, such as a display, a microphone, and a speaker) with which the electronic device 3 is provided. Moreover, although one acoustic generator 1 was illustrated in FIG. 7, two or more acoustic generators 1 and other transmitters can be provided.

  The control circuit 301 controls the entire electronic device 3 including the wireless circuit 303 via the signal processing circuit 302. An output signal to the sound generator 1 is input from the signal processing circuit 302. Then, the control circuit 301 generates a sound signal S by controlling the signal processing circuit 302 from the signal input to the radio circuit 303 and outputs the sound signal S to the sound generator 1.

  In this way, the electronic device 3 shown in FIG. 7 incorporates the small and thin acoustic generator 1 and reduces the difference between the resonance peak and the dip to suppress the frequency fluctuation as much as possible. It is possible to improve the sound quality as a whole even in a high sound region including a low sound region having a low sound level.

  In FIG. 7, the electronic device 3 in which the sound generator 1 is directly mounted is illustrated as the sound output device. However, as the sound output device, for example, the sound generator 2 in which the sound generator 1 is housed in the housing is mounted. It may be the configuration.

(Second Embodiment)
FIG. 8 is a schematic plan view showing the sound generator 1 according to the second embodiment. As shown in FIG. 8, in the acoustic generator 1 according to the second embodiment, the first region 11 a and the second region 12 a are vibration surfaces on which the piezoelectric vibration element 20 of the vibrating body 10 is provided. 10a is arranged side by side in the lateral direction (X-axis direction).

  Specifically, the first region 11a and the second region 12a are a line 13a that is substantially orthogonal to the short direction in the vibration surface 10a, in other words, substantially parallel to the longitudinal direction (Y-axis direction) in the vibration surface 10a. It is defined by a line 13a. The line 13a is, for example, a line that divides the area of the vibration surface 10a into upper and lower parts in the plan view of FIG.

  In FIG. 8, the position of the line 13a that divides the first area 11a and the second area 12a is illustrated, but the position of the line 13a is not limited to this, and the first and second areas Any position may be used as long as it divides the vibration surface 10a so that the regions 11a and 12a are arranged in the short direction.

  The damping material 60 is attached to the surface of the covering portion 50 corresponding to the first region 11 a of the vibrating body 10 as in the first embodiment described above. Specifically, the damping material 60 is disposed, for example, on the surface of the covering portion 50 corresponding to the first region 11a, in the vicinity of the piezoelectric vibration element 20 in plan view, and along the longitudinal direction of the frame 30. The In addition, it is the same as that of 1st Embodiment that arrangement | positioning of the damping material 60 is not limited to the example of illustration.

  As a result, the load acting on the vibrating body 10 is different between the first region 11a and the second region 12a, and therefore, in the standing wave W of the vibration generated in the vibrating body 10, the vibration in the first region 11a. The distance L1 between the nodes of the standing wave W is different from the distance L2 between the nodes of the standing wave W of the vibration in the second region 12a.

  Therefore, even in the sound generator 1 according to the second embodiment, it is difficult for strong resonance to occur at a specific frequency. As a result, the difference between the resonance peak and the dip is reduced in the frequency characteristics of sound pressure, and sound is reduced. The frequency fluctuation of the pressure can be suppressed as much as possible, and the sound quality can be improved. The remaining configuration and effects are the same as those in the first embodiment, and a description thereof will be omitted.

  FIG. 9 shows another arrangement example of the first and second areas. As shown in FIG. 9, the first region 11b and the second region 12b are band-like regions including the diagonal line 14 of the vibration surface 10a on which the piezoelectric vibration element 20 of the vibrating body 10 is provided (specifically, FIG. 9 may be arranged side by side in the direction of the diagonal line 14.

  Specifically, the first region 11b and the second region 12b are formed by being partitioned by a line 13b substantially orthogonal to the diagonal line 14 in the belt-like region 15 of the vibration surface 10a. The line 13b is, for example, a line that divides the area of the band-like region 15 of the vibration surface 10a substantially equally into an upper right part and a lower left part in the plan view of FIG.

  In addition, the position of the line 13b shown in FIG. 9 is an illustration and is not limited. That is, the line 13b may be at any position as long as the first and second areas 11b and 12b are positioned to divide the band-like area 15 so that they are aligned in the direction of the diagonal line 14.

  The damping material 60 is attached to the surface of the covering portion 50 corresponding to the first region 11b of the vibrating body 10 as in the first and second embodiments described above. Specifically, the damping material 60 is disposed, for example, on the surface of the covering portion 50 corresponding to the first region 11 a and in the vicinity of the corner portion of the frame body 30.

  Accordingly, also in the example illustrated in FIG. 9, the load acting on the vibrating body 10 is different between the first region 11 b and the second region 12 b, and in the standing wave W of the vibration generated in the vibrating body 10, The node interval L1 of the vibration standing wave W in the first region 11b is made different from the node interval L2 of the vibration standing wave W in the second region 12b.

  Therefore, even in the example shown in FIG. 9, since it is difficult for strong resonance to occur at a specific frequency, it is possible to reduce the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure and to change the frequency of the sound pressure. As a result, the sound quality can be improved. Note that each modification described in the first embodiment can also be applied to the sound generator 1 according to the second embodiment and the sound generator 1 shown in FIG. 9.

  In the above-described embodiment, the position where the first region 11, 11 a, 11 b and the second region 12, 12 a, 12 b are arranged in the vibrating body 10 has been specifically described. It is not limited. In short, in the sound generator 1, if the first regions 11, 11 a, 11 b and the second regions 12, 12 a, 12 b are arranged on the vibrating body 10 so as to reduce the difference between the resonance peak and the dip. Good.

  In the above-described embodiment, the piezoelectric vibration element 20 is disposed on the same surface of the vibration surface 10a of the vibrating body 10, but may be disposed on both surfaces. Further, although the piezoelectric vibration element 20 is rectangular in plan view, it may be square.

  Moreover, although the vibration surface 10a of the vibrating body 10 is rectangular, this is illustrative and is not limited, and may be other shapes such as a polygonal shape other than the rectangular shape, a circular shape, an elliptical shape, and the like. . That is, the shape of the frame 30, more precisely, the shape of the inside (inner edge) of the frame 30 may be other shapes such as a polygonal shape other than a rectangular shape, a circular shape or an elliptical shape, for example.

  In the above description, the case where the frame 30 is configured by the two frame members 30a and 30b and the outer peripheral portion of the vibrating body 10 is sandwiched and supported by the two frame members 30a and 30b is taken as an example. However, it is not limited to this. For example, the frame body 30 may be configured by a single frame member, and the outer peripheral portion of the vibrating body 10 may be bonded and fixed to the frame body 30 to be supported.

  Further, as the piezoelectric vibration element 20, a so-called bimorph type laminated type is illustrated, but a unimorph type piezoelectric vibration element can also be used.

  In addition, the case where the exciter is the piezoelectric vibration element 20 has been described as an example, but the exciter is not limited to the piezoelectric vibration element, and has a function of vibrating when an electric signal is input. It is good if it is. For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter well known as an exciter for vibrating a speaker may be used. The electrodynamic exciter is such that an electric current is passed through a coil disposed between the magnetic poles of a permanent magnet to vibrate the coil. The electrostatic exciter is composed of two metals facing each other. A bias and an electric signal are passed through the plate to vibrate the metal plate, and an electromagnetic exciter is an electric signal that is passed through the coil to vibrate a thin iron plate.

  In the above-described embodiment, the piezoelectric vibration element 20 and the vibrating body 10 are covered with the covering portion 50. However, the present invention is not limited to this, and a configuration without the covering portion 50 may be used.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Sound generator 2 Sound generator 3 Electronic device 10 Vibrating body 11, 11a, 11b 1st area | region 12, 12a, 12b 2nd area | region 20 Piezoelectric vibration element 30 Frame body 40 Joint part 50 Covering part 60 Damping material 200 Resonance Box (housing)
300 Housing 301 Control circuit 302 Signal processing circuit 303 Radio circuit 304 Antenna

Claims (10)

A thin plate-like vibrator,
An exciter provided on the vibrator,
The vibrator is provided with a second region in which the distance between the first region and the node of the standing wave of vibration is different from the distance of the node of the standing wave of vibration in the first region on the surface where the exciter is provided. And an acoustic generator. The sound generator according to claim 1, wherein the first region and the second region are arranged on the surface of the vibrator on which the exciter is provided with the exciter interposed therebetween. . The sound generator according to claim 1, wherein the first region and the second region are arranged side by side in a longitudinal direction of a surface of the vibrator on which the exciter is provided. The sound generator according to claim 1, wherein the first region and the second region are arranged side by side in a short direction of a surface of the vibrator on which the exciter is provided. The surface of the vibrator on which the exciter is provided is polygonal, and the first region and the second region are a band-like region including a diagonal line of the surface on which the exciter of the vibrator is provided. The sound generator according to claim 1, wherein the sound generator is arranged side by side in the diagonal direction. A damping material integrated with the vibrator and the exciter;
The acoustic generator according to any one of claims 1 to 5, wherein the arrangement of the damping material is different between the first region and the second region. The acoustic generator according to claim 1, wherein the exciter is a piezoelectric vibration element. The acoustic generator according to claim 7, wherein the piezoelectric vibration element is of a bimorph type. The sound generator according to any one of claims 1 to 8,
A housing that houses the acoustic generator;
A sound generator comprising: The sound generator according to any one of claims 1 to 8,
An electronic circuit connected to the acoustic generator;
A housing for housing the electronic circuit and the acoustic generator;
Comprising at least
An electronic device having a function of generating sound from the sound generator.

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