JP2014086753A - Electroacoustic transducer, manufacturing method therefor, and electronic apparatus using electroacoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute to the emission of high quality sound and also to contribute to the restriction of deterioration in the directivity of sound to be emitted.SOLUTION: An electroacoustic transducer includes basic oscillation units that are arranged in parallel on a plane. The basic oscillation units include: piezoelectric vibrators; vibration members for restraining the piezoelectric vibrators; and a frame that encloses the piezoelectric vibrators and the vibration members and where sound hole parts are formed in a direction to be intersected with the vibration direction of the piezoelectric vibrators. The sound hole parts are formed at positions to avoid the interference of reverse-phase sonic waves to be emitted from the other sound hole parts.

Description

  The present invention relates to an electroacoustic transducer, a manufacturing method thereof, and an electronic apparatus using the electroacoustic transducer.

  In recent years, a highly directional parametric speaker that propagates sound to a person at a specific position has attracted attention. For example, it is expected that a parametric speaker is mounted on an electronic device such as a mobile phone and an audio signal is propagated in the vicinity of the user.

  Here, when a parametric speaker is mounted on an electronic device such as a mobile phone, the parametric speaker is required to be downsized. However, it is difficult to reduce the size of an electrodynamic electroacoustic transducer using a magnetic circuit because of its principle. Therefore, the use of an electroacoustic transducer using a piezoelectric vibrator is expected.

  Patent Document 1 discloses a speaker system in which speakers are arranged so that opposing speakers output sound having the same phase. And in the speaker system disclosed by patent document 1, the sound path of the sound output from the facing speaker is formed.

JP 2002-291099 A

  The disclosure of the above prior art document is incorporated herein by reference. The following analysis has been made from the viewpoint of the present invention.

  As described above, the use of an electroacoustic transducer using a piezoelectric vibrator is expected. Furthermore, it is preferable that the electroacoustic transducer oscillates a sound wave having a high sound pressure level in order to radiate a high-quality sound. Therefore, the electroacoustic transducer preferably includes a plurality of piezoelectric vibrators. However, when the electroacoustic transducer includes a plurality of piezoelectric vibrators, sound waves oscillated from the piezoelectric vibrators may interfere with each other. And when the sound wave oscillated from each piezoelectric vibrator interferes, the directivity of the emitted sound becomes weak.

  With the technique disclosed in Patent Document 1, it is impossible to suppress interference of sound waves oscillated from each piezoelectric vibrator.

  Therefore, an electroacoustic transducer that contributes to radiating high-quality sound and contributes to suppressing directivity degradation of the radiated sound, a manufacturing method thereof, and an electronic device using the electroacoustic transducer are provided. ,desired.

  According to a first aspect of the present invention, the piezoelectric vibrator, the vibration member that restrains the piezoelectric vibrator, the piezoelectric vibrator, and the vibration member are included, and intersect the vibration direction of the piezoelectric vibrator. A basic oscillation unit including a frame having a sound hole portion in a direction in which the sound hole portion is arranged in parallel on a plane, and the sound hole portion radiates from the other sound hole portion. An electroacoustic transducer is provided that is formed in a position that avoids interference.

  According to a second aspect of the present invention, the piezoelectric vibrator, the vibration member that restrains the piezoelectric vibrator, the piezoelectric vibrator, and the vibration member are included, and intersect the vibration direction of the piezoelectric vibrator. A basic oscillation unit including a frame having a sound hole portion in a direction in which the sound hole portion is arranged in parallel on a plane, and the sound hole portion radiates from the other sound hole portion. There is provided an electronic device that includes an electroacoustic transducer formed at a position that avoids interference and oscillates the piezoelectric vibrator to emit ultrasonic waves having a frequency of 20 kHz or more.

  According to a third aspect of the present invention, there is provided a method of manufacturing an electroacoustic transducer comprising a piezoelectric vibrator, a vibrating member that restrains the piezoelectric vibrator, a frame, and a sound hole portion, A step of enclosing a vibrator and the vibration member in the frame; a step of arranging a basic oscillation unit including the piezoelectric vibrator, the vibration member, and the frame in parallel on a plane; and the frame. And forming the sound hole portion at a position that is in a direction that intersects the vibration direction of the piezoelectric vibrator and that avoids interference of sound waves of opposite phase radiated from the other sound hole portions; A method of manufacturing an electroacoustic transducer is provided.

  According to each aspect of the present invention, it contributes to radiating high-quality sound, its manufacturing method that contributes to suppressing directivity degradation of the radiated sound, and an electron using the electroacoustic transducer Equipment is provided.

It is a figure for demonstrating the outline | summary of one Embodiment. It is a section side view showing an example of electroacoustic transducer 1 concerning a 1st embodiment. 1 is a cross-sectional side view illustrating an example of a piezoelectric vibrator 10 according to a first embodiment. 2 is a cross-sectional side view showing an example of a basic oscillation unit 11 according to the first embodiment. FIG. It is a figure which shows an example of the structure which concerns on 1st Embodiment, and the structure which concerns on a comparison form. It is a figure which shows an example of the measurement result of a frequency and a sound pressure level. It is a section side view showing an example of basic oscillation unit 11a concerning a 2nd embodiment.

  First, an outline of an embodiment will be described with reference to FIG. Note that the reference numerals of the drawings attached to the outline are attached to the respective elements for convenience as an example for facilitating understanding, and the description of the outline is not intended to be any limitation.

  As described above, the electroacoustic transducer preferably oscillates a sound wave having a high sound pressure level in order to radiate a high-quality sound. Furthermore, when the electroacoustic transducer includes a plurality of piezoelectric vibrators, it is preferable to suppress a decrease in directivity of the emitted sound. Therefore, there is a demand for an electroacoustic transducer that contributes to radiating high-quality sound and contributes to suppressing directivity degradation of the radiated sound.

  Therefore, the electroacoustic transducer 100 shown in FIG. 1 is provided as an example. First, the electroacoustic transducer 100 includes basic oscillation units 101 arranged in parallel on a plane. The basic oscillation unit 101 includes a piezoelectric vibrator 102 and a vibration member 103 that restrains the piezoelectric vibrator 102. The piezoelectric vibrator 102 oscillates by applying an electric field and oscillates a sound wave. The vibration member 103 amplifies the vibration generated by the piezoelectric vibrator 102. Further, in the basic oscillation unit 101, the piezoelectric vibrator 102 and the vibration member 103 are included in the frame 104.

  In the frame 104, a sound hole portion 105 is formed in a direction crossing the vibration direction of the piezoelectric vibrator 102. Further, in the electroacoustic transducer 100, the sound hole portion 105 is formed at a position that avoids interference of sound waves emitted from the other sound hole portions 105. Therefore, in the electroacoustic transducer 100, interference of sound waves oscillated from the piezoelectric vibrator 102 is suppressed.

  Further, since the electroacoustic transducer 100 includes the plurality of piezoelectric vibrators 102, it can emit sound waves having a high sound pressure level. Furthermore, the directivity of the electroacoustic transducer 100 can be enhanced by selectively driving one or more of the piezoelectric vibrators 102. That is, a sound field can be formed in a specific direction by selectively driving the piezoelectric vibrator 102. Therefore, the electroacoustic transducer 100 contributes to radiating high-quality sound and contributes to suppressing a decrease in directivity of the radiated sound.

  In the present invention, the following modes are possible.

  [Mode 1] As in the electroacoustic transducer according to the first aspect.

  [Mode 2] It is preferable that the sound hole portion is formed in the frame such that an interval between the sound hole portions adjacent to each other is 1/8 or less of a wavelength of an oscillation wave.

  [Mode 3] The sound hole portion is preferably formed in a direction of 90 degrees or more with respect to the vibration direction of the piezoelectric vibrator.

  [Mode 4] It is preferable that the vibration member is joined to the frame via a support member.

  [Mode 5] It is preferable that the piezoelectric vibrator oscillates an ultrasonic wave having a frequency of 20 kHz or more.

  [Mode 6] As in the electronic apparatus according to the second aspect.

  [Mode 7] The method of manufacturing the electroacoustic transducer according to the third aspect.

  [Mode 8] In the method of manufacturing an electroacoustic transducer, the sound hole portion is formed in the frame so that an interval between adjacent sound hole portions is 1/8 or less of a wavelength of an oscillation wave. It is preferable to include a process.

  [Mode 9] The method for manufacturing the electroacoustic transducer preferably includes a step of forming the sound hole portion in a direction of 90 degrees or more with respect to a vibration direction of the piezoelectric vibrator.

  [Mode 10] The method for manufacturing the electroacoustic transducer preferably includes a step of joining the vibration member to the frame via a support member.

  Hereinafter, specific embodiments will be described in more detail with reference to the drawings.

[First Embodiment]
The first embodiment will be described in more detail with reference to the drawings. In the following description, many specific items are made for the purpose of explanation and to help understanding of the present invention.

  First, the basic structure of the electroacoustic transducer 1 according to this embodiment will be described.

  FIG. 2 is a cross-sectional side view showing an example of the electroacoustic transducer 1 according to the present embodiment. For simplicity, FIG. 2 mainly describes members related to the electroacoustic transducer 1 according to the present embodiment.

  The electroacoustic transducer 1 is used as a speaker device, for example. The speaker device may be a parametric speaker. When the electroacoustic transducer 1 is used as a parametric speaker, the piezoelectric vibrator 10 preferably oscillates ultrasonic waves of 20 kHz or higher. In this case, the parametric speaker propagates an audio signal using ultrasonic waves as a carrier wave. Then, the parametric speaker radiates the modulated ultrasonic wave to the atmosphere, thereby inducing a collision wave accompanying a nonlinear phenomenon in the air and reproducing the demodulated sound.

  Furthermore, the piezoelectric vibrator 10 oscillates ultrasonic waves with high straightness, so that a sound field with high directivity can be formed. As a result, the electroacoustic transducer 1 according to the present embodiment can radiate sound waves around the vicinity of the user.

  The electroacoustic transducer 1 is preferably a sound source such as a smartphone, a mobile phone, a game machine, a tablet PC (Personal Computer), a notebook PC, or a PDA (Personal Data Assistants).

  The piezoelectric vibrator 10 is composed of a piezoelectric body 21 polarized in the thickness direction and is restrained by the vibration member 20. The piezoelectric vibrator 10 oscillates and oscillates by application of an electric field. Therefore, it is preferable that the electronic apparatus including the electroacoustic transducer 1 includes an oscillation circuit (not shown) that generates an electric signal to be applied to the piezoelectric body 21.

  The piezoelectric vibrator 10 and the vibration member 20 are included in the frame 12. In the frame 12, a sound hole portion 13 is formed in a direction crossing the vibration direction of the piezoelectric vibrator 10. That is, the oscillation wave from the piezoelectric vibrator 10 is radiated in a direction that intersects the vibration direction of the piezoelectric vibrator 10. Specifically, the sound hole portion 13 is preferably formed in a direction of 90 degrees or more with respect to the vibration direction of the piezoelectric vibrator 10. In particular, the sound hole portion 13 is preferably formed in a direction of 90 degrees or more and 150 degrees or less with respect to the vibration direction of the piezoelectric vibrator 10.

  And it is preferable that the sound hole part 13 is formed in the position which avoids the interference by the sound wave of the antiphase radiated | emitted from the other sound hole part 13. FIG. Specifically, the sound hole portion 13 is preferably formed in the frame 12 so that the interval between the adjacent sound hole portions 13 is 1/8 or less of the wavelength of the oscillation wave.

  FIG. 3 is a cross-sectional side view illustrating an example of the piezoelectric vibrator 10. For simplicity, FIG. 3 mainly describes members related to the piezoelectric vibrator 10 according to the present embodiment.

  The piezoelectric body 21 has electrodes 22 constrained on both main surfaces. That is, the piezoelectric body 21 is polarized in the thickness direction. The material constituting the piezoelectric body 21 is a material having a piezoelectric effect, and may be either an inorganic material or an organic material. For example, piezoelectric ceramics such as lead zirconate titanate and barium titanate may be used. There are various preferred materials for the piezoelectric body 21, and details thereof are not limited.

  Moreover, although the material which comprises the electrode 22 is not limited, For example, silver and silver / palladium may be sufficient. Silver has a low electrical resistivity and is used as a general-purpose electrode material. Silver / palladium has a low electrical resistivity and is excellent in oxidation resistance. There are various preferred materials for the electrode 22, but the details are not limited.

  As described above, the piezoelectric body 21 is preferably a piezoelectric ceramic, but the piezoelectric ceramic is brittle. Therefore, when the piezoelectric body 21 is made of piezoelectric ceramic, it is difficult to change the shape of the piezoelectric body 21. Therefore, it is preferable to change the resonance frequency by changing the thickness, material, and the like of the vibration member 20 that restrains the piezoelectric body 21.

  The vibration member 20 is preferably made of a material having high rigidity with respect to the piezoelectric body 21. When the rigidity of the vibration member 20 is too low or too high, the characteristics and reliability as a mechanical vibrator may be impaired. For example, the vibration member 20 may be a metal material such as phosphor bronze or stainless steel. Alternatively, the vibration member may be a composite material of a metal material and a resin. By making the vibration member 20 a composite material of a metal material and a resin, it is possible to contribute to adjusting the rigidity of the vibration member 20. There are various preferable materials for the vibration member 20, and details thereof are not limited.

  FIG. 4 is a cross-sectional side view showing an example of the basic oscillation unit 11 according to the present embodiment. For simplicity, FIG. 4 mainly describes members related to the basic oscillation unit 11 according to the present embodiment.

  The first electrical connection terminal 231 is preferably connected to the electrode 22 constrained on the vibration surface of the piezoelectric vibrator 10. Furthermore, in the vibration member 20, it is preferable to connect the second electrical connection terminal 232 to the surface in contact with the electrode 22 and the opposing surface.

  FIG. 5 is a diagram illustrating an example in which the structures of the piezoelectric body 21 and the vibration member 20 are compared. Fig.5 (a) is a figure which shows an example of the structure of the electroacoustic transducer 1 which concerns on this embodiment. On the other hand, FIG. 5B is a diagram illustrating an example of the structure of the electroacoustic transducer 2 in which the piezoelectric body 21 and the vibration member 20 are not surrounded by the frame 12 and the vibration member 20 is restrained by the frame 12. 5A and 5B, the electroacoustic transducer 1 including the piezoelectric vibrator 10 is arranged in parallel on a plane. In the following description, the structure of the electroacoustic transducer 1 shown in FIG. 5A is referred to as “structure according to the present embodiment”. On the other hand, the structure of the electroacoustic transducer 2 shown in FIG.

  Moreover, FIG. 6 is a figure which shows an example of the measurement result of a frequency and a sound pressure level about the structure concerning this embodiment, and the structure concerning a comparison form. A solid line indicates a measurement result in the structure according to the present embodiment. A broken line shows the measurement result in the structure which concerns on a comparison form. In FIG. 6, it is assumed that the physical property values of the common members are the same in the structure according to the present embodiment and the structure according to the comparative embodiment. Furthermore, in FIG. 6, it is assumed that the measurement conditions including the temperature and the like are the same in the structure according to the present embodiment and the structure according to the comparative embodiment.

  As shown in FIG. 6, in both the structure according to the present embodiment and the structure according to the comparative embodiment, the sound pressure level has a peak value at a frequency of about 60 kHz. However, in the frequency band shown in FIG. 6 (about 10 kHz to about 100 kHz), the structure according to the present embodiment has a smaller dispersion of sound pressure than the structure according to the comparative example. That is, it can be seen from the measurement results shown in FIG. 6 that the structure according to the present embodiment has higher oscillation efficiency than the structure according to the comparative form. Needless to say, the frequency at which the sound pressure level reaches its peak, the sound pressure level, and the like vary depending on the shape, physical properties, measurement conditions, and the like of each member.

[Modification 1]
As a first modification of the electroacoustic transducer 1 according to this embodiment, the length of each piezoelectric vibrator 10 may be changed. The electroacoustic transducer 1 may selectively drive one or a plurality of piezoelectric vibrators 10. This is because the resonance frequency of the sound wave oscillated by the piezoelectric vibrator 10 and the length of the piezoelectric vibrator are in an inversely proportional relationship. Therefore, the resonance frequency of each piezoelectric vibrator 10 can be changed by changing the length of each piezoelectric vibrator 10. Therefore, by demodulating the ultrasonic waves oscillated from the piezoelectric vibrators 10 having different resonance frequencies, the band of the audible sound to be demodulated can be expanded.

  As described above, the first effect of the electroacoustic transducer 1 according to the present embodiment is that the interference of sound waves from adjacent piezoelectric vibrators is reduced. Therefore, the electroacoustic transducer 1 contributes to radiating high-quality sound and contributes to suppressing a decrease in directivity of the radiated sound.

  The second effect of the electroacoustic transducer 1 according to the present embodiment is that the distance between the adjacent piezoelectric vibrators 10 is shortened as compared with the case where the sound hole portion 13 is formed in front of the vibration direction of the piezoelectric vibrator 10. Can be arranged. Therefore, the electroacoustic transducer 1 contributes to miniaturization of a parametric speaker or the like.

[Second Embodiment]
Next, the second embodiment will be described in detail with reference to the drawings.

  The second embodiment is an embodiment of a structure that reduces the impact when dropped. In the description of the present embodiment, the description of the same parts as those in the first embodiment is omitted. Further, in the description of the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 7 is a cross-sectional side view showing an example of the basic oscillation unit 11a according to the second embodiment. A difference between the basic oscillation unit 11 a shown in FIG. 7 and the basic oscillation unit 11 shown in FIG. 4 is that a support member 24 is provided.

  In the basic oscillation unit 11 a, the vibration member 20 is joined to the frame 12 via the support member 24. In addition, the first electrical connection terminal 231 is disposed on the electrode 22 positioned in front of the piezoelectric vibrator 10 in the vibration direction. Further, in the vibrating member 20, the second electrical connection terminal 232 is disposed on the surface in contact with the electrode 22.

  The material constituting the support member 24 is not limited as long as the material absorbs vibration. For example, the material constituting the support member 24 may be a resin material. The support member 24 contributes to reducing the rigidity of the end portion where stress concentrates when the piezoelectric vibrator 10 vibrates. The support member 24 contributes to amplifying the vibration of the piezoelectric vibrator 10.

  Further, in the basic oscillation unit 11 a, the piezoelectric body 21 is joined to the frame 12 via the support member 24. When the support member 24 is a resin material or the like, the support member 24 absorbs an impact. Therefore, in the basic oscillation unit 11a according to the present embodiment, when the basic oscillation unit 11a is dropped, the impact on the piezoelectric body 21 is reduced.

  As described above, the first effect of the electroacoustic transducer 1 according to the present embodiment is that the oscillation efficiency of sound waves is further improved. This is because, in the electroacoustic transducer 1 according to the present embodiment, the vibration member 20 is joined to the frame 12 via the support member 24. Therefore, the electroacoustic transducer 1 according to the present embodiment further amplifies the vibration of the piezoelectric vibrator 10.

  The second effect of the electroacoustic transducer 1 according to this embodiment is that the impact at the time of dropping is reduced. This is because the support member 24 absorbs the impact. Therefore, the impact on the piezoelectric body 21 is reduced when dropped.

  The disclosure of the cited patent document is incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. In addition, various combinations of various indication elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the scope of the claims of the present invention, Selection is possible. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea. In particular, with respect to the numerical ranges described in this document, any numerical value or small range included in the range should be construed as being specifically described even if there is no specific description.

1, 2, 100 Electroacoustic transducers 10, 102 Piezoelectric vibrators 11, 11a, 101 Basic oscillation unit 12, 104 Frame 13, 105 Sound hole portion 20, 103 Vibration member 21 Piezoelectric body 22 Electrode 24 Support member 231 First Electrical connection terminal 232 Second electrical connection terminal

Claims (10)

A piezoelectric vibrator;
A vibrating member that restrains the piezoelectric vibrator;
A frame that includes the piezoelectric vibrator and the vibration member, and has a sound hole portion formed in a direction intersecting a vibration direction of the piezoelectric vibrator;
Are arranged in parallel on a plane,
The sound hole part is formed at a position that avoids interference of sound waves of opposite phases radiated from the other sound hole parts,
An electroacoustic transducer characterized by that.   2. The electroacoustic transducer according to claim 1, wherein the sound hole portion is formed in the frame such that an interval between adjacent sound hole portions is 1/8 or less of a wavelength of an oscillation wave.   The electroacoustic transducer according to claim 1, wherein the sound hole portion is formed in a direction of 90 degrees or more with respect to a vibration direction of the piezoelectric vibrator.   The electroacoustic transducer according to any one of claims 1 to 3, wherein the vibration member is joined to the frame via a support member.   The electroacoustic transducer according to claim 1, wherein the piezoelectric vibrator oscillates an ultrasonic wave having a frequency of 20 kHz or more.   An electronic apparatus comprising the electroacoustic transducer according to claim 1, wherein the piezoelectric vibrator oscillates so as to emit an ultrasonic wave having a frequency of 20 kHz or more. A piezoelectric vibrator;
A method of manufacturing an electroacoustic transducer comprising a vibrating member that restrains the piezoelectric vibrator, a frame, and a sound hole portion,
Including the piezoelectric vibrator and the vibrating member in the frame;
Disposing a basic oscillation unit including the piezoelectric vibrator, the vibration member, and the frame in parallel on a plane;
Forming the sound hole in the frame at a position that intersects the vibration direction of the piezoelectric vibrator and avoids interference of sound waves of opposite phase that are emitted from the other sound hole. When,
The manufacturing method of the electroacoustic transducer characterized by including.   The electroacoustic transducer according to claim 7, further comprising a step of forming the sound hole portion in the frame such that an interval between adjacent sound hole portions is 1/8 or less of a wavelength of an oscillation wave. Production method.   The method for manufacturing an electroacoustic transducer according to claim 7 or 8, comprising a step of forming the sound hole portion in a direction of 90 degrees or more with respect to a vibration direction of the piezoelectric vibrator.   The method for manufacturing an electroacoustic transducer according to claim 7, further comprising a step of joining the vibration member to the frame via a support member.

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