JP6034182B2 - SOUND GENERATOR, SOUND GENERATOR, AND ELECTRONIC DEVICE - Google Patents

Description

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

  Conventionally, an acoustic generator using an actuator is known (see, for example, Patent Document 1). Such an acoustic generator outputs sound by vibrating a diaphragm by applying a voltage to an actuator attached to the diaphragm to vibrate.

JP 2009-130663 A

  However, since the above-described conventional sound generator actively uses the resonance of the diaphragm, the frequency characteristics of the sound pressure have a peak (a portion where the sound pressure is higher than the surroundings) and a dip (the sound pressure is higher than the surroundings). There is a problem that it is difficult to obtain a high-quality sound quality.

  One embodiment of the present invention has been made in view of the above, and an object thereof is to provide an acoustic generator, an acoustic generator, and an electronic apparatus that can obtain a favorable frequency characteristic of sound pressure.

  An acoustic generator according to an aspect of an embodiment includes an exciter that receives an electric signal and vibrates, a flat vibrator that is attached to the exciter and vibrates with the exciter due to vibration of the exciter, An acoustic generator having at least a vibrator and a support that vibrates together with the exciter and the vibrator by vibration of the exciter, wherein a damping material is disposed in contact with the support .

  According to one aspect of the embodiment, a favorable sound pressure frequency characteristic can be obtained.

(A) is a typical top view which shows schematic structure of a basic sound generator, (B) is the sectional view on the A-A 'line of FIG. 1A. It is a figure which shows an example of the frequency characteristic of a sound pressure. (A) is a typical top view which shows the structure of the acoustic generator which concerns on embodiment, (B) is a B-B 'line schematic sectional drawing of FIG. 3A. (A) is a schematic plan view (part 1) showing a specific arrangement example of the damping material, (B) is a schematic plan view (part 2) showing a specific arrangement example of the damping material. is there. (A) is a schematic plan view (part 3) showing a specific arrangement example of the damping material, (B) is a schematic plan view (part 4) showing a specific arrangement example of the damping material. is there. (A) is a schematic front view showing a specific arrangement example of the damping material (part 1), (B) is a schematic front view showing a specific arrangement example of the damping material (part 2), and (C) is a damping material. It is a front schematic diagram (the 3) which shows the specific example of arrangement | positioning. (A) is a figure which shows the structure of the sound generator which concerns on embodiment, (B) is a figure which shows the structure of the electronic device which concerns on embodiment.

  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, prior to the description of the sound generator 1 according to the embodiment, a schematic configuration of a basic sound generator 1 ′ will be described with reference to FIGS. 1A and 1B. 1A is a schematic plan view showing a schematic configuration of the acoustic generator 1 ′, and FIG. 1B is a cross-sectional view taken along line A-A ′ of FIG. 1A.

  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. Moreover, in FIG. 1A, illustration of the resin layer 7 is omitted.

  Similarly, for easy understanding, FIG. 1B greatly exaggerates the sound generator 1 ′ in the thickness direction (Z-axis direction).

  As shown in FIG. 1A, the sound generator 1 ′ includes a frame body 2, a diaphragm 3, and a piezoelectric element 5. As shown in FIG. 1A, in the following description, the case where there is one piezoelectric element 5 is illustrated unless otherwise specified, but the number of piezoelectric elements 5 is not limited.

  The frame body 2 is configured by two frame members having the same shape of a rectangular frame shape, and functions as a support body that supports the diaphragm 3 with the peripheral edge portion of the diaphragm 3 interposed therebetween. The diaphragm 3 has a plate shape or a film shape, and a peripheral portion thereof is sandwiched and fixed by the frame body 2. That is, the diaphragm 3 is supported while being stretched in the frame of the frame body 2. In addition, the part located inside the frame 2 among the diaphragms 3, ie, the part which is not pinched by the frame 2 among the diaphragms 3, and can vibrate freely is made into the vibrating body 3a. Therefore, the vibrating body 3 a is a portion having a substantially rectangular shape in the frame of the frame body 2.

  The diaphragm 3 can be formed using various materials such as resin and metal. For example, the diaphragm 3 can be made of a resin film such as polyethylene or polyimide having a thickness of about 10 to 200 μm.

  The thickness and material of the frame 2 are not particularly limited. The frame 2 can be formed using various materials such as metal and resin. For example, a stainless steel member having a thickness of about 100 to 1000 μm can be suitably used as the frame 2 because it has excellent mechanical strength and corrosion resistance.

  Although FIG. 1A shows the frame 2 in which the shape of the inner region is substantially rectangular, it may be a polygon such as a parallelogram, trapezoid, or regular n-gon. In this embodiment, as shown to FIG. 1A, the example which is substantially rectangular shape is shown.

  The piezoelectric element 5 is an exciter that is provided by being affixed to the surface of the vibrating body 3a and that excites the vibrating body 3a by receiving a voltage to vibrate.

As shown in FIG. 1B, the piezoelectric element 5 includes, for example, a laminate in which piezoelectric layers 5a, 5b, 5c, and 5d made of four ceramic layers and three internal electrode layers 5e are alternately laminated, Surface electrode layers 5f and 5g formed on the upper and lower surfaces of the laminate, and external electrodes 5h and 5j formed on the side surfaces where the internal electrode layer 5e is exposed. The lead terminals 6a and 6b are connected to the external electrodes 5h and 5j.

  The piezoelectric element 5 has a plate shape, and the main surface on the upper surface side and the lower surface side has a polygonal shape such as a rectangular shape or a square shape. The piezoelectric layers 5a, 5b, 5c, and 5d are polarized as shown by arrows in FIG. 1B. In other words, polarization is performed such that the direction of polarization with respect to the direction of the electric field applied at a certain moment is reversed between one side and the other side in the thickness direction (Z-axis direction in the figure).

  When a voltage is applied to the piezoelectric element 5 via the lead terminals 6a and 6b, for example, at a certain moment, the piezoelectric layers 5c and 5d on the side bonded to the vibrating body 3a contract and the upper surface of the piezoelectric element 5 is compressed. The piezoelectric layers 5a and 5b on the side are deformed so as to extend. Accordingly, by applying an AC signal to the piezoelectric element, the piezoelectric element 5 can bend and vibrate, and the vibrating body 3a can be bent.

  In addition, the main surface of the piezoelectric element 5 is joined to the main surface of the vibrating body 3a by an adhesive such as an epoxy resin.

In addition, as a material constituting the piezoelectric layers 5a, 5b, 5c, and 5d, a lead-free piezoelectric material such as PZT (lead zirconate titanate), Bi layered compound, tungsten bronze structure compound, or the like has been conventionally used. Piezoelectric ceramics can be used.

  Various metal materials can be used as the material of the internal electrode layer 5e. For example, when a metal component composed of silver and palladium and a ceramic component constituting the piezoelectric layers 5a, 5b, 5c, and 5d are contained, the piezoelectric layers 5a, 5b, 5c, and 5d and the internal electrode layer 5e Since the stress due to the difference in thermal expansion can be reduced, the piezoelectric element 5 having no stacking failure can be obtained. The lead terminals 6a and 6b can be formed using various metal materials. For example, if the lead terminals 6a and 6b are configured using flexible wiring in which a metal foil such as copper or aluminum is sandwiched between resin films, the height of the piezoelectric element 5 can be reduced.

  Further, as shown in FIG. 1B, the sound generator 1 ′ is disposed so as to cover the surfaces of the piezoelectric element 5 and the vibrating body 3 a within the frame 2, and is integrated with the vibrating body 3 a and the piezoelectric element 5. The resin layer 7 is further provided.

  The resin layer 7 is preferably formed using, for example, an acrylic resin so that the Young's modulus is about 1 MPa to 1 GPa. In addition, since an appropriate damping effect can be induced by embedding the piezoelectric element 5 with the resin layer 7, the resonance phenomenon can be suppressed and the peak or dip in the frequency characteristic of the sound pressure can be suppressed to a small level. .

  FIG. 1B shows a state in which the resin layer 7 is formed so as to be the same height as the frame 2, but it is sufficient that the piezoelectric element 5 is embedded, for example, the resin layer 7 has a frame. It may be formed to be higher than the height of the body 2.

  Further, in FIG. 1B, as the piezoelectric element 5, a bimorph type stacked piezoelectric element is taken as an example, but the present invention is not limited to this. For example, it may be a unimorph type in which a piezoelectric element that expands and contracts is attached to the vibrating body 3a.

By the way, as shown in FIG. 1A and FIG. 1B, the acoustic generator of this example has the piezoelectric element 5 attached to the vibrating body 3a stretched on the frame body 2 and covered with the resin layer 7, so that the frame body 2, the vibrating body 3a, the piezoelectric element 5 and the resin layer 7 are integrated, and the frame 2, the vibrating body 3a,
The piezoelectric element 5 and the resin layer 7 vibrate integrally.

  In such a composite vibration body constituted by the frame body 2, the vibration body 3a, the piezoelectric element 5 and the resin layer 7, the frame body 2, the vibration body 3a and the resin layer 7 are vibrations of the piezoelectric element 5 which is a vibration source. Are propagated at their own frequencies depending on their size (vertical length, horizontal length, diagonal length and thickness) and hardness, and these vibrations are added together to generate sound. The frequency-sound pressure characteristics of the instrument.

  However, when the composite vibrating body composed of the frame body 2, the vibrating body 3a, the piezoelectric element 5 and the resin layer 7 has symmetry as a whole, the peak is concentrated at a specific frequency. A steep peak or dip is likely to occur. This point is illustrated in FIG.

  As an example, attention is paid to a portion surrounded by a broken closed curve PD in FIG. When such a peak occurs, the sound pressure varies depending on the frequency, making it difficult to obtain good sound quality.

  In such a case, it is effective to take measures such as reducing the height of the peak P (see arrow 201 in the figure) and widening the peak width (see arrow 202 in the figure) to reduce the peak or dip.

  Therefore, in this embodiment, first, it is assumed that the damping material 8 is disposed in contact with the frame 2 of the sound generator 1. Note that the damping material 8 being disposed in contact with the frame body 2 means that the damping material 8 is disposed so as to be in contact with the upper surface, side surfaces, and corners of the frame body 2. Is more preferably disposed in contact with the vibrating body 3 a and the piezoelectric element 5.

  Thus, by arranging the damping material 8 in contact with the frame body 2, the resonance peak of the sound pressure is suppressed by the damping material 8, so that the peak dip is reduced and the flatness of the frequency-sound pressure characteristics is improved. Is done.

  Moreover, it is preferable that the acoustic generator 1 of this embodiment is arrange | positioned so that the gravity center of the damping material 8 may not overlap with the gravity center of the acoustic generator 1 when planarly viewed. As a result, the peak or dip of the sound pressure can be further reduced.

  Furthermore, it is preferable that the damping material 8 is plural. By using a plurality of damping materials 8, it is possible to selectively improve the frequency region targeted for sound quality improvement and obtain better sound quality.

  Further, the plurality of damping materials 8 may be disposed at non-target positions with respect to the center of gravity of the sound generator 1, may have different areas, may have different thicknesses, may have different materials, or may have different masses. preferable. By arranging such a plurality of damping materials 8, the resonance peak of sound pressure can be suppressed more pinpointed, and the flatness of frequency-sound pressure characteristics can be improved.

  Note that the damping material 8 may be disposed in contact with the frame body 2, and an effect can be obtained regardless of the presence or absence of the resin layer 7.

Hereinafter, it demonstrates concretely using FIG. 3A-FIG. 4B. 3A is a schematic plan view showing the configuration of the sound generator 1 according to the embodiment, and FIG. 3B is a schematic cross-sectional view taken along the line BB ′ shown in FIG. 3A. 4A to 4B are layout explanatory views (No. 1) to (No. 2) of the damping material 8 when the diaphragm 3 is viewed in plan.

  As shown in FIG. 3A, the sound generator 1 includes a damping material 8 in addition to the sound generator 1 'shown in FIGS. 1A and 1B. FIG. 3A illustrates the case where one rectangular damping material 8 straddles the frame body 2 and the vibrating body 3a and is in contact with the frame body 2, but the shape, the number, and the region of the arrangement However, it is only necessary that the damping material 8 is in contact with the frame body 2.

  The damping material 8 may have any mechanical loss, but is preferably a member having a high mechanical loss factor, in other words, a low mechanical quality factor (so-called mechanical Q).

  Such a damping material 8 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. The damping material 8 is attached to the surfaces of the frame 2 and the resin layer 7 shown in FIG. 1B and is integrated with the frame 2, the vibrating body 3 a, the piezoelectric element 5, and the resin layer 7.

  By providing the damping material 8 in this manner, the region where the damping material 8 is disposed receives vibration loss due to the damping material 8 via the resin layer 7 and the frame body 2, thereby suppressing the resonance phenomenon. It will be.

  In addition, the outer peripheral shape of the damping material 8 is not limited to the elliptical shape and the rectangular shape as shown in FIGS. 4A to 4B, but a deformed shape such as a semicircular shape, a crescent shape, a star shape, a pentagonal shape, a hexagonal shape, It may be a polygonal shape or a circular shape.

  Moreover, it is preferable that the damping material 8 is disposed so that its center of gravity does not overlap with the center of gravity of the sound generator 1 when viewed in plan. If the center of gravity of the damping material 8 and the center of gravity of the sound generator 1 overlap, there is a risk of conversely increasing the sound pressure peak or dip.

  Next, the sound generator according to another aspect of the embodiment has a plurality of damping materials 8 as shown in FIGS. 5A to 5B. FIG. 5A is a plan view in which two damping members 8 are disposed across the frame body 2 and in contact with the frame body 2 over the frame body 2 and the vibrating body 3a, and FIG. 5 is a plan view in which one of the damping members 8 is disposed across the frame body 2 and the vibrating body 3a and the other is disposed in contact with the frame body 2 at the upper portion of the vibrating body 3a.

  By using a plurality of damping materials 8, it is possible to selectively improve the frequency region targeted for sound quality improvement and obtain better sound quality.

  In addition, the plurality of damping materials 8 are preferably arranged at non-target positions with respect to the center of gravity of the sound generator 1. By arranging a plurality of damping materials 8 at non-target positions with respect to the center of gravity of the sound generator 1, the respective resonance frequencies caused by the diagonal lines, vertical and horizontal lengths of the sound generator 1 and the piezoelectric element 5, Peaks and dip caused by the anti-resonance frequency can be suppressed, and as a result, the sound pressure peak and dip level can be further reduced.

  Further, the same effects as described above can be obtained by making the areas of the plurality of damping materials 8 different, changing the outer peripheral shape, making the thickness different, making the material different, or making the mass different.

  6A to 6C are cross-sectional views (No. 1) to (No. 3) showing specific examples of arrangement of the damping material 8. FIG. 6A to 6C are cross-sectional views taken along line A-A ′ (see FIG. 1A) of the sound generator 1.

  FIG. 6A is an arrangement example in which the damping material 8 is disposed across the frame body 2 and the vibration body 3a on the main surface side of the diaphragm 3 provided with the piezoelectric elements 5, and FIG. This is an arrangement example in which the vibration body 3a on the main surface opposite to the main surface side of the diaphragm 3 provided with the piezoelectric element 5 is disposed so as to be in contact with the frame body 2.

  As shown in FIG. 6C, for example, when the bimorph type piezoelectric element 5 is attached with the diaphragm 3 sandwiched from both sides, a resin layer 7 is also formed on the lower surface side of the diaphragm 3, and the lower surface A damping material 8 may be provided on the side so as to contact the frame body 2.

  Next, a sound generation device and an electronic device equipped with the sound generator 1 according to the embodiment described so far will be described with reference to FIGS. 7A and 7B. FIG. 7A is a diagram illustrating a configuration of the sound generation device 20 according to the embodiment, and FIG. 7B is a diagram illustrating a configuration of the electronic device 50 according to the embodiment. In addition, in both figures, only the component required for description is shown and description about a general component is abbreviate | omitted.

  The sound generation device 20 is a sound generation device such as a so-called speaker, and includes, for example, a sound generator 1 and a housing 30 that houses the sound generator 1 as shown in FIG. 7A. The housing 30 resonates the sound generated by the sound generator 1 and radiates the sound to the outside through an opening (not shown) formed in the housing 30. By having such a housing 30, for example, the sound pressure in a low frequency band can be increased.

  The sound generator 1 can be mounted on various electronic devices 50. For example, in FIG. 7B shown below, the electronic device 50 is assumed to be a mobile terminal device such as a mobile phone or a tablet terminal.

  As illustrated in FIG. 7B, the electronic device 50 includes an electronic circuit 60. The electronic circuit 60 includes, for example, a controller 50a, a transmission / reception unit 50b, a key input unit 50c, and a microphone input unit 50d. The electronic circuit 60 is connected to the sound generator 1 and has a function of outputting an audio signal to the sound generator. The sound generator generates sound based on the sound signal input from the electronic circuit.

  The electronic device 50 includes a display unit 50e, an antenna 50f, and the sound generator 1. Further, the electronic device 50 includes a housing 40 that accommodates these devices.

  7B shows a state in which each device including the controller 50a is accommodated in one housing 40, but the accommodation form of each device is not limited. In the present embodiment, it is sufficient that at least the electronic circuit 60 and the sound generator 1 are accommodated in one housing 40.

  The controller 50 a is a control unit of the electronic device 50. The transmission / reception unit 50b transmits / receives data via the antenna 50f based on the control of the controller 50a.

  The key input unit 50c is an input device of the electronic device 50 and accepts a key input operation by an operator. The microphone input unit 50d is also an input device of the electronic device 50, and accepts a voice input operation by an operator.

  The display unit 50e is a display output device of the electronic device 50, and outputs display information based on the control of the controller 50a.

  The sound generator 1 operates as a sound output device in the electronic device 50. The sound generator 1 is connected to the controller 50a of the electronic circuit 60, and emits sound upon application of a voltage controlled by the controller 50a.

  In FIG. 7B, the electronic device 50 is described as a portable terminal device. However, the electronic device 50 is not limited to the type of the electronic device 50, and may be applied to various consumer devices having a function of emitting sound. . For example, flat-screen TVs and car audio devices can of course be used for products having a function of emitting sound such as "speak", for example, various products such as vacuum cleaners, washing machines, refrigerators, microwave ovens, etc. .

  In the embodiment described above, the case where the piezoelectric element 5 is provided on one main surface of the vibrating body 3a has been mainly described as an example. However, the present invention is not limited to this, and the both surfaces of the vibrating body 3a are provided. A piezoelectric element 5 may be provided.

  Further, in the above-described embodiment, the case where the shape of the inner region of the frame is a substantially rectangular shape is taken as an example, and it may be a polygon, but is not limited thereto, and is not limited to a circle or an ellipse. It may be a shape.

  In the above-described embodiment, the case where the resin layer 7 is formed so as to cover the piezoelectric element 5 and the vibrating body 3a in the frame of the frame body 2 is taken as an example. However, such a resin layer is not necessarily formed. Also good.

  Further, in the above-described embodiment, the case where the diaphragm is configured by a thin film such as a resin film has been described as an example. However, the present invention is not limited thereto, and may be configured by a plate-like member, for example.

  In the above-described embodiment, the case where the support body that supports the vibrating body 3a is the frame body 2 and the periphery of the vibrating body 3a is supported as an example. However, the present invention is not limited to this. For example, it is good also as supporting only the both ends of the longitudinal direction or the transversal direction of the vibrating body 3a. In this case, the damping material 8 should just be arrange | positioned in contact with the member which supports the vibrating body 3a.

  In the above-described embodiment, the case where the exciter is the piezoelectric element 5 has been described as an example. However, the exciter is not limited to the piezoelectric element, and a function that vibrates when an electric signal is input thereto. As long as it has. 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.

  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, 1 'Sound generator 2 Frame body 3 Diaphragm 3a Vibration body 5 Piezoelectric element 5a, 5b, 5c, 5d Piezoelectric layer 5e Internal electrode layer 5f, 5g Surface electrode layer 5h, 5j External electrode 6a, 6b Lead terminal 7 Resin layer 8 Damping material 20 Sound generator 30, 40 Housing 50 Electronic device 50a Controller 50b Transmitter / receiver 50c Key input unit 50d Microphone input unit 50e Display unit 50f Antenna 60 Electronic circuit P Peak

Claims (8)

An exciter that vibrates upon receipt of an electrical signal;
A flat vibrator that is mounted with the exciter and vibrates with the exciter by vibration of the exciter;
A support that stretches the vibrator and vibrates with the exciter and the vibrator by the vibration of the exciter;
A resin layer disposed so as to cover the surface of the vibrator to which the exciter and the exciter are attached;
Sound generator and having a a damping member disposed such that the exciter and the vibrator and the non-contact as well as come in contact with the resin layer and the support. The damping material is
The sound generator according to claim 1, wherein the sound generator is arranged so that a center of gravity of the damping material does not overlap with a center of gravity of the sound generator when viewed in a plan view. The damping material is
The sound generator according to claim 1 or 2, wherein there are a plurality of sound generators. A plurality of said damping material, sound generator according to claim 3, characterized in that it is arranged at the position of the asymmetric with respect to the center of gravity of the sound generator. The acoustic generator according to claim 3 or 4, wherein the plurality of damping materials have different areas. The sound generator according to claim 3, wherein the plurality of damping materials have different thicknesses. The sound generator according to any one of claims 1 to 6 ,
And a housing for housing the sound generator. The sound generator according to any one of claims 1 to 6 ,
An electronic circuit connected to the acoustic generator;
A housing for housing the electronic circuit and the acoustic generator,
An electronic apparatus having a function of generating sound from the sound generator.

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