JP6166038B2 - 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, a sound generator comprising at least a support which vibrates with exciter and the vibration member by the vibration exciter with which stretched the vibrator, Ri outer peripheral shape is elliptical der of the vibrating body, the outer periphery of the support The shape is rectangular, and the long axis direction and the short axis direction of the outer peripheral shape of the vibrating body are not the same as the diagonal direction, the long side direction, and the short side direction of the outer peripheral shape of the support body .

  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 vibrating body, (B) is a schematic plan view (part 2) showing a specific arrangement example of the vibration body. 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 (C) ) Is a schematic plan view (part 5) showing a specific arrangement example of the damping material. (A) is a figure which shows the structure of the acoustic 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. FIG. 1A shows an example in which the shape of the inner region is a substantially rectangular shape that is often found in the past.

  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 free from stacking faults 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 FIGS. 1A and 1B, the acoustic generator of this example has the piezoelectric element 5 attached to the vibrating body 3a and covered with the resin layer 7, so that the vibrating body 3a, the piezoelectric element 5 and the resin layer are covered. 7 is integrated, and the vibrating body 3a, the piezoelectric element 5 and the resin layer 7 vibrate integrally.

  When such a composite vibrating body composed of the vibrating body 3a, the piezoelectric element 5 and the resin layer 7 has symmetry as a whole, the peak concentrates on a specific frequency, and 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 the present embodiment, first, the outer peripheral shape of the vibrating body 3a is an elliptical shape. The elliptical shape means not only a mathematically defined elliptical shape but also a general shape consisting of a curved line whose outer periphery is convex outward.

  In this way, by using the vibrating body 3a having an elliptical outer peripheral shape, the resonance frequency is dispersed in various frequencies as compared with the vibrating body 3a having a substantially rectangular outer peripheral shape. And dip are less likely to occur, and the flatness of the frequency-sound pressure characteristics can be improved.

  Moreover, since the sound generator of this embodiment becomes easy to generate | occur | produce the peak and dip of a sound pressure in a specific frequency when the outer periphery shape of the frame 2 is a rectangular shape with symmetry, it is easy to generate | occur | produce the vibration body 3a. The effect by making an outer periphery shape into an elliptical shape is large.

  Furthermore, it is preferable that the major axis direction and the minor axis direction of the vibrating body 3 a do not overlap with the diagonal direction, the long side direction, and the short side direction of the frame body 2. By preventing the major axis direction and the minor axis direction of the vibrating body 3a from overlapping with the diagonal direction, the long side direction, and the short side direction of the support body 2, the resonance / antiresonance frequencies of the vibrating body 3a and the frame body It is possible to prevent the resonance and anti-resonance frequencies of 2 from overlapping, and it is possible to improve the flatness of the frequency-sound pressure characteristics.

  Further, it is preferable that the center of gravity of the frame body 2 and the center of gravity of the vibrating body 3a do not overlap. Since the center of gravity of the frame 2 and the center of gravity of the vibrating body 3a do not overlap, the flatness of the frequency-sound pressure characteristics can be further improved.

  Hereinafter, it demonstrates concretely using FIG. 3A-FIG. 4B. FIG. 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 line B-B ′ shown in FIG. 3A. 4A to 4C are layout explanatory views (No. 1) to (No. 2) of the vibrating body 3a when the diaphragm 3 is viewed in plan.

  As shown in FIG. 3A, in the sound generator 1, the outer peripheral shape of the vibrating body 3a is elliptical with respect to the sound generator 1 'shown in FIGS. 1A and 1B. The outer peripheral shape of the vibrating body 3a means not only the elliptical shape defined by mathematics as described above, but also the entire shape including a curved line whose outer periphery is convex outward. The lengths of the major axis and the minor axis are the lengths of the long side and the short side of the frame 2 and the vertical and horizontal lengths of the piezoelectric element 5 according to the frequency-sound pressure characteristics required of the sound generator 1. It is decided as appropriate together. In addition, the frame body 2 has a function of holding the diaphragm 3 and fixing the sound generator 1 to a sound generation device to be described later. From such a viewpoint, the narrowest part of the width of the frame body The width is about 1 to 10 mm, preferably 2 to 8 mm.

Moreover, as shown to FIG. 4A, it is preferable to set it as the structure which the major axis direction and short-axis direction of the vibrating body 3a do not overlap with the diagonal direction of the frame 2, the long-side direction, and the short-side direction. By adopting a configuration in which the major axis direction and the minor axis direction of the vibrating body 3a do not overlap with the diagonal direction, the long side direction, and the short side direction of the frame body 2, the flatness of the frequency-sound pressure characteristics is improved. It becomes possible.

  Furthermore, as shown in FIG. 4B, it is preferable that the center of gravity of the frame 2 and the center of gravity of the vibrating body 3a do not overlap. By adopting a configuration in which the center of gravity of the frame body 2 and the center of gravity of the vibrating body 3a do not overlap, it is possible to further improve the flatness of the frequency-sound pressure characteristics.

  Further, as shown in FIGS. 5A to 5C, it is preferable to dispose a damping material 8 on at least one of the frame body 2, the vibrating body 3 a, the piezoelectric element 5, and the resin layer 7. By arranging the damping material 8 on at least one of the frame 2, the vibrating body 3a, the piezoelectric element 5 and the resin layer 7, it is possible to directly dampen the vibration peak by the damping material 8. Thus, by adopting the configuration in which the outer peripheral shape of the vibrating body 3a is an elliptical shape, it is possible to improve the flatness of the frequency-sound pressure characteristics.

  5A to 5C, when one rectangular damping material 8 is disposed on the upper portion of the piezoelectric element 5, when disposed on the upper portion across the piezoelectric element 5 and the vibrating body 3a, The case where the piezoelectric element 5, the vibrating body 3 a, and the frame 2 are disposed at the upper part is illustrated, but the shape, the number, and the arrangement region are not limited, and the damping material 8 is the frame 2. It is only necessary to be disposed on at least one of the vibrating body 3a, the piezoelectric element 5 and the resin layer 7.

  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 surface of the resin layer 7 shown in FIG. 1B and is integrated with the vibrating body 3a, the piezoelectric element 5, and the resin layer 7.

  By providing the damping material 8 in this way, the region where the damping material 8 is disposed receives vibration loss due to the damping material 8 via the resin layer 7, thereby suppressing the resonance phenomenon.

  The outer peripheral shape of the damping material 8 may be an elliptical shape, a quadrangular shape, a triangular shape, a semicircular shape, a crescent shape, a star shape, a polygonal shape such as a pentagonal shape or a hexagonal shape, or a circular shape.

  Next, a sound generation device and an electronic apparatus equipped with the sound generator 1 according to the embodiment described so far will be described with reference to FIGS. 6A and 6B. FIG. 6A is a diagram illustrating a configuration of the sound generation device 20 according to the embodiment, and FIG. 6B 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. 6A. 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. 6B shown below, it is assumed that the electronic device 50 is a mobile terminal device such as a mobile phone or a tablet terminal.

  As shown in FIG. 6B, 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.

  6B 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. 6B, 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.

  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 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;
An acoustic generator having at least
The outer peripheral shape of the vibrating body is an elliptical shape,
The outer peripheral shape of the support is rectangular,
A sound generator, wherein a major axis direction and a minor axis direction of the outer peripheral shape of the vibrating body are not the same as a diagonal direction, a longer side direction, and a shorter side direction of the outer peripheral shape of the support body. The outer shape of the exciter is rectangular,
The sound generation according to claim 1, wherein a major axis direction and a minor axis direction of the outer peripheral shape of the vibrating body and a diagonal direction, a longer side direction, and a shorter side direction of the outer peripheral shape of the exciter are not the same. vessel. The sound generator according to claim 1 or 2, wherein the center of gravity of the support and the center of gravity of the vibrating body do not overlap.   A damping material is disposed above at least one of the support, the vibrator, and the exciter.
The sound generator according to any one of claims 1 to 3. 2. The apparatus according to claim 1, further comprising: a resin layer disposed so as to cover the exciter and the surface of the vibrator to which the exciter is attached, and integrated with the vibrator and the exciter. 4. The sound generator according to any one of 3. 6. The sound generator according to claim 5, wherein a damping material is disposed on at least one of the support, the vibrator, the exciter, and the resin layer. 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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