JP2012029103A - Oscillation device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small size oscillation device which enables high volume playback.SOLUTION: Multiple vibration members 110 are spaced apart from each other in a direction perpendicular to a plane and parts of the vibration members 110 are overlapped in the arrangement direction. Centers of multiple piezoelectric elements 120 are arranged so as not to overlap the adjacent vibration members 110 in the arrangement direction. Thus, sound waves generated by the multiple piezoelectric elements 120 are output from clearances formed by the multiple vibration members 110. Therefore, the device enables high volume playback while reducing the size of the entire shape.

Description

  The present invention relates to an oscillation device including a piezoelectric element, and more particularly, to an oscillation device in which a piezoelectric element is mounted on a vibration member, and an electronic apparatus having the oscillation device.

  In recent years, demand for portable electronic devices such as mobile phones and notebook computers has been increasing. In such an electronic device, development of a thin portable terminal whose commercial value is an acoustic function such as a videophone, a video playback, and a hands-free phone is being promoted. Under such development, there is an increasing demand for high-quality sound, small size, and thinness for electroacoustic transducers (speaker devices) that are acoustic components.

  At present, electrodynamic electroacoustic transducers have been used as electroacoustic transducers in electronic devices such as mobile phones. This electrodynamic electroacoustic transducer is composed of a permanent magnet, a voice coil, and a diaphragm.

  However, there is a limit to reducing the thickness of electrodynamic electroacoustic transducers due to their operating principle and structure. On the other hand, Patent Documents 1 and 2 describe using a piezoelectric element as an electroacoustic transducer.

  As other examples of an oscillation device using a piezoelectric element, there are various types of devices such as a speaker device and a sound wave sensor (Patent Document 3) that detects a distance to an object using a sound wave oscillated from a piezoelectric element. There are known electronic devices and oscillation devices.

No. 2007-026736 Table 2007-083497 Japanese Patent Laid-Open No. 03-270282

  An oscillating device using a piezoelectric element uses a piezoelectric effect of the piezoelectric element to generate a vibration amplitude by an electrostrictive action by inputting an electric signal. An electrodynamic electroacoustic transducer generates vibration by a piston-type advance / retreat movement, whereas an oscillation device using a piezoelectric element has a bending-type vibration state and thus has a small amplitude. For this reason, it is superior in reducing the thickness of the electrodynamic electroacoustic transducer described above.

  However, in the acoustic performance of the electroacoustic transducer, the sound pressure level indicating the sound volume is determined by the volume exclusion amount of the diaphragm with respect to the air. In other words, since it depends on the radiation area and amplitude of vibration, the radiation area decreases when downsizing, so it is difficult in principle to achieve both miniaturization and high volume.

  The present invention has been made in view of the above-described problems, and provides an oscillation device capable of reproducing a large volume while being small.

  An oscillation device according to the present invention includes a plurality of elastic vibration members, a plurality of piezoelectric elements that are individually bonded to at least one of the front and back surfaces of each of the plurality of vibration members, and that contract and vibrate by application of an electric field; And supporting members that support the plurality of vibration members at both ends in a predetermined direction, and the plurality of vibration members are spaced apart in a direction perpendicular to each other and have overlapping side portions in the arrangement direction, and the center of the piezoelectric element is arranged in the arrangement direction. They are arranged at positions that do not overlap with adjacent vibrating members.

  A first electronic device of the present invention includes the oscillation device of the present invention and oscillation drive means for causing the oscillation device to output an audible sound wave.

  The second electronic device according to the present invention includes an oscillation device according to the present invention, an oscillation drive unit that outputs an ultrasonic wave to the oscillation device, and an ultrasonic detection that detects an ultrasonic wave oscillated from the oscillation device and reflected from an object to be measured. Means, and distance calculation means for detecting the distance from the detected ultrasonic wave to the measurement object.

  In the oscillation device of the present invention, the plurality of vibration members are spaced apart in the perpendicular direction and partially overlap in the arrangement direction, and the centers of the plurality of piezoelectric elements are arranged in positions that do not overlap with adjacent vibration members in the arrangement direction. As a result, sound waves generated by the plurality of piezoelectric elements can be output from the gaps between the plurality of vibration members, so that a large volume can be reproduced while reducing the overall shape.

It is a perspective view which shows the internal structure of the electroacoustic transducer which is an oscillation apparatus of the 1st embodiment of this invention. It is a vertical front view which shows the structure of an electroacoustic transducer. It is a bottom view which shows the structure of an electroacoustic transducer. It is a vertical side view which shows the structure of the principal part of an electroacoustic transducer. It is a typical side view which shows the polarization direction of a piezoelectric element. It is a schematic diagram which shows the operation | movement principle of the electroacoustic transducer of 2nd Embodiment. It is a typical vertical side view which shows the structure of the principal part of the electroacoustic transducer of 3rd Embodiment. It is a schematic diagram which shows the principle of operation of the principal part of the electroacoustic transducer of 3rd Embodiment. It is a disassembled perspective view which shows the structure of the piezoelectric element of the electroacoustic transducer of 4th Embodiment. It is a vertical side view which shows the structure of the principal part of the electroacoustic transducer of 5th Embodiment. It is a vertical side view which shows the structure of the principal part of the electroacoustic transducer of 6th Embodiment. It is a typical front view which shows the external appearance of the mobile telephone which is embodiment of the electronic device of this invention. It is a typical front view showing the appearance of a personal computer which is an embodiment of electronic equipment of the present invention. It is a vertical front view which shows the structure of the electroacoustic transducer of one modification.

[First embodiment]
A first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 to 3, an electroacoustic transducer 100 that is an oscillation device according to the present embodiment includes an elastic diaphragm 110 that is a plurality of elastic members having elasticity, and a plurality of elastic diaphragms 110. A plurality of piezoelectric elements 120 that are individually bonded to at least one of the front surface and the back surface and vibrate in response to application of an electric field; and a main body housing 130 that is a support member that supports the plurality of elastic diaphragms 110 at both ends in a predetermined direction; Have.

  In the electroacoustic transducer 100 according to the present embodiment, as shown in FIG. 2, the plurality of elastic diaphragms 110 are separated in the direction perpendicular to each other, and the side portions overlap in the arrangement direction, and the piezoelectric elements are arranged in the arrangement direction. The centers of 120 are arranged at positions that do not overlap with the adjacent elastic diaphragm 110.

  In the electroacoustic transducer 100 of the present embodiment, the plurality of elastic diaphragms 110 are each formed in an elongated shape wider than the plurality of piezoelectric elements 120, and are in the arrangement direction of the wide elastic diaphragms 110. An elongated piezoelectric element 120 is disposed at the center of the lower surface in the short direction.

  In addition, since the plurality of elastic diaphragms 110 are arranged at positions where the piezoelectric element 120 and the elastic diaphragm 110 to which the other piezoelectric elements 120 are joined do not overlap in the short direction, the plurality of elastic diaphragms 110 are The plurality of piezoelectric elements 120 are arranged at positions that do not overlap in the short direction.

  More specifically, in the electroacoustic transducer 100 of the present embodiment, the main body housing 130 is formed in a rectangular frame shape that opens in the vertical direction. Five elastic diaphragms 110 and five piezoelectric elements 120 are prepared, and are arranged in a V-shaped front shape inside the main body housing 130 as shown in FIG.

  In the electroacoustic transducer 100 according to the present embodiment, the sound waves output from the plurality of piezoelectric elements 120 are emitted in the vertical direction from the gaps between the plurality of elastic diaphragms 110 by the arrangement as described above.

  Further, in this configuration, since the piezoelectric element 120 is a simple configuration made of the piezoelectric element 120 and an elastic material, the thickness is superior to the conventional electrodynamic electroacoustic transducer. That is, even if the piezoelectric element 120 (for example, 0.2 mm) and the elastic material (0.3 mm) are joined, the thickness is about 0.5 mm. Even if the piezoelectric element 120 is formed in three stages, the thickness is 2 mm or less, and about 3 mm. This is superior to a certain conventional electrodynamic electroacoustic transducer 100.

  In addition, the electroacoustic transducer 100 of the present embodiment performs sound reproduction using ultrasonic waves (details of the operation principle will be described separately). For this reason, even in this embodiment in which a plurality of piezoelectric elements 120 are formed in parallel, it is possible to radiate sound waves satisfactorily.

  That is, the directivity of the ultrasonic wave is narrow, and the sound wave goes straight in the direction toward the radiation surface. On the other hand, in the conventional electroacoustic transducer 100 that emits sound waves in the audible band, when the piezoelectric elements 120 are arranged in parallel as in this configuration, sound wave interference and canceling occur, and sound wave radiation characteristics are reduced. to degrade.

  That is, since the directivity is wider than that of a high frequency band that generates ultrasonic waves, such as 100 kHz, with respect to a low frequency band, such as 500 Hz, the sound waves propagate to other piezoelectric elements 120 that are arranged vertically and horizontally. There is a problem that sound waves generated from the piezoelectric element 120 cause interference and canceling.

  Here, the manufacturing method of the electroacoustic transducer 100 of this invention is demonstrated below. First, the piezoelectric element 120 has a piezoelectric plate 121 having an outer diameter = 10 × 5 mm and a thickness = 200 μm (0.02 mm), and an upper electrode layer 122 having a thickness of 8 μm on each of both surfaces as shown in FIG. A lower electrode layer 123 is formed.

  The piezoelectric plate 121 of the piezoelectric element 120 was made of lead zirconate titanate ceramic, and the electrode layers 122 and 123 were made of silver / palladium alloy (70% by weight: 30%). The piezoelectric ceramic was manufactured by a green sheet method, fired in the atmosphere at 1100 ° C. for 2 hours, and then the piezoelectric element 120 layer was subjected to polarization treatment.

  The elastic diaphragm 110 is formed of phosphor bronze having an outer diameter = 12 × 6 mm and a thickness = 300 μm (0.3 mm). The main body housing 130 is formed of SUS304, and the piezoelectric element 120 is joined to the main body housing 130 via the elastic diaphragm 110.

  The main body housing 130 has a rectangular parallelepiped shape of length × width × width = 20 × 14 × 2 mm, and is formed of SUS304 having a thickness of 0.5 mm. Bonding of the piezoelectric element 120 and the elastic diaphragm 110 and bonding of the main body housing 130 were both performed using an epoxy adhesive.

  The operation principle of the electroacoustic transducer 100 of the present invention will be described below. The electroacoustic transducer 100 according to the present invention generates sound waves from a plurality of piezoelectric elements 120 arranged in parallel toward a radiation surface. Although the frequency is not particularly limited, it is preferably outside the audible band, for example, 100 KHz or the like is suitable for using a sound wave as a modulated wave transporter.

  The piezoelectric element 120 of the electroacoustic transducer 100 according to the present embodiment has a principal surface on one side constrained by the elastic diaphragm 110. At the same time, the elastic diaphragm 110 has a function of adjusting the fundamental resonance frequency of the piezoelectric element 120. The fundamental resonance frequency f of the mechanical elastic diaphragm 110 depends on the load weight and compliance, as shown by the following equation.

[Equation 1]
f = 1 / (2πL√ (mC))
“M” is mass and “C” is compliance.

  In other words, since the compliance is the mechanical rigidity of the elastic diaphragm 110, this means that the fundamental resonance frequency can be controlled by controlling the rigidity of the piezoelectric element 120.

  For example, the fundamental resonance frequency can be shifted to a low range by selecting a material having a high elastic modulus and reducing the thickness of the elastic diaphragm 110. On the other hand, the fundamental resonance frequency can be shifted to a high range by selecting a material having a high elastic modulus or increasing the thickness of the elastic diaphragm 110.

  Conventionally, since the basic resonance frequency was controlled by the shape and material of the piezoelectric element 120, there were problems in design constraints, cost, and reliability. As in the present invention, the elastic diaphragm as a constituent member Since it can be easily adjusted to a desired fundamental resonance frequency by changing 110, the industrial value is great.

  In this configuration, since the five piezoelectric elements 120 emit sound waves, five times as much acoustic energy can be radiated as compared with an electroacoustic transducer composed of one piezoelectric element. Next, a sound reproduction method will be described. In this configuration, the operating principle of a parametric speaker is used.

  Here, AM (Amplitude Modulation) modulation, DSB (Double Sideband modulation) modulation, SSB (Single-Sideband modulation) modulation, FM (Frequency Modulation) modulated ultrasonic waves are emitted into the air, and the ultrasonic waves are in the air. Sound reproduction is performed on the principle that an audible sound appears due to nonlinear characteristics when propagating to the sound.

  Here, non-linearity includes a phenomenon in which laminar flow transitions to turbulent flow when the Reynolds number indicated by the ratio between the inertial action and the viscous action of the flow increases. That is, since the sound wave is slightly disturbed in the fluid, the sound wave propagates in a non-linear manner.

  However, the amplitude of the sound wave in the low frequency band is non-linear, but the amplitude difference is very small, and is usually handled as a phenomenon of linear theory. On the other hand, nonlinearity can be easily observed with ultrasonic waves, and when radiated into the air, harmonics accompanying the nonlinearity are remarkably generated.

  In summary, sound waves are a dense state where molecular groups are mixed in the air, and if it takes time for air molecules to recover rather than compress, air that cannot be recovered after compression will continue to propagate through the air. This is the principle that an audible sound is generated by colliding with a molecule and generating a shock wave.

  Next, the operation principle of the piezoelectric element 120 will be described. As shown in FIG. 5, the piezoelectric element 120 is composed of the piezoelectric plate 121 (piezoelectric ceramic) having two main surfaces as described above, and the upper electrode layer 122 and the lower electrode are respectively formed on the main surfaces of the piezoelectric plate 121. A layer 123 is formed.

  The polarization direction of the piezoelectric plate 121 is not particularly limited, but in the present embodiment, it is upward in the vertical direction (thickness direction of the piezoelectric element 120) in the figure. In the piezoelectric element 120 configured in this manner, when an alternating voltage is applied to the upper electrode layer 122 and the lower electrode layer 123 and an alternating electric field is applied, both main surfaces are expanded or contracted simultaneously. Performs radial expansion and contraction (diameter expansion).

  In other words, the piezoelectric element 120 performs a motion that repeats a first deformation mode in which the main surface expands and a second deformation mode in which the main surface contracts. The basic principle of the electroacoustic transducer 100 of the present invention is to generate vibration and sound by repeating such movement.

  As described above, in the electroacoustic transducer 100 according to the present embodiment, the plurality of elastic diaphragms 110 are separated in the vertical direction that is the perpendicular direction and partially overlaps in the horizontal direction that is the short direction, The centers of the plurality of piezoelectric elements 120 are arranged at positions that do not overlap in the left-right direction.

  For this reason, the sound waves output from the plurality of piezoelectric elements 120 are emitted in the vertical direction from the gaps between the plurality of elastic diaphragms 110. Nevertheless, since the plurality of elastic diaphragms 110 are arranged so as to partially overlap in the short direction, the electroacoustic transducer 100 of the present embodiment can reproduce a large volume while reducing the overall structure. Is possible.

  Moreover, in the electroacoustic transducer 100 of this Embodiment, since the ultrasonic wave is utilized, directivity is narrow and industrial value is large at points, such as a user's privacy protection. That is, the electroacoustic transducer 100 according to the present embodiment has higher rectilinearity of the sound wave than the existing electroacoustic transducer, and can selectively propagate the sound wave to a position to be transmitted to the user.

  In summary, the electroacoustic transducer 100 of the present invention is used as a sound source of an electronic device (for example, a mobile phone as shown in FIG. 12, a notebook personal computer, a small game device as shown in FIG. 13, etc.). Is also available. Since the electroacoustic transducer 100 can be prevented from increasing in size and the acoustic characteristics are improved, the electroacoustic transducer 100 can be suitably used for portable electronic devices.

[Second embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, a sound reproduction method different from that of the first embodiment is adopted. The electroacoustic transducer that is the oscillation device of the present embodiment has a structure in which two electroacoustic transducers 100 are arranged in parallel (not shown).

  These electroacoustic transducers simultaneously generate two sound waves, a modulated ultrasonic wave and a non-modulated fundamental wave, and reproduce an audible sound due to a frequency shift between them. As shown in FIG. 6, when two ultrasonic waves interfere in the internal space, heterodyne detection is generated, and only AM modulation or FM modulation is generated as an audible wave.

  Since the electroacoustic transducer (not shown) of the present embodiment has a plurality of piezoelectric elements 120, two types of ultrasonic waves can be easily generated. Moreover, the frequency which generate | occur | produces an ultrasonic wave will not be specifically limited if it is 20 KHz or more other than an audible band.

[Third embodiment]
A third embodiment of the present invention will be described with reference to FIG. In the electroacoustic transducer (not shown) of the present embodiment, each of the plurality of elastic diaphragms 110 is constrained by two piezoelectric elements 120 as compared to the first embodiment. That is, a bimorph structure using two piezoelectric elements 120.

  As shown in FIG. 8, the bimorph type piezoelectric elements 120 and 120 are formed by bonding two piezoelectric ceramics whose polarization directions are opposite to each other, bending one by extending in the longitudinal direction, and shrinking the other. Compared to a unimorph structure composed of a single piezoelectric element 120 in the first embodiment, a larger displacement can be obtained.

  For the two piezoelectric elements 120, the same piezoelectric material as in the first embodiment can be used. Further, the two piezoelectric elements 120 may have the same shape or different shapes.

[Fourth embodiment]
A fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the piezoelectric element 12 has a multilayer structure in which piezoelectric plates 13a to 13e made of a piezoelectric material are stacked in five layers.

  Between the piezoelectric plates 13a to 13e, electrode layers (conductor layers) 14a to 14d are formed one by one. The polarization directions of the piezoelectric plates 13a to 13e are opposite to each other, and the direction of the electric field is also alternately opposite.

  According to the piezoelectric element 12 having such a laminated structure, since the electric field strength generated between the electrode layers 14a to 14d is high, the driving force of the piezoelectric element 12 as a whole according to the number of laminated piezoelectric plates 13a to 13e. Will improve.

[Fifth embodiment]
A fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, elastic diaphragm 110 is bonded to main body housing 130 with low-rigidity resin material 140 interposed.

  By interposing the resin material 140 in this manner, the fixed state of the elastic diaphragm 110 and the main body housing 130 can be brought closer to the free end, the vibration movable range is expanded, and the amount of amplitude is also increased.

  Further, the impact at the time of dropping can be absorbed by the resin material 140 having a high flexibility, and the impact stability is also improved. The resin material 140 is not particularly limited as long as it is an organic polymer material, but urethane, PET, polyethylene and the like are preferable.

[Sixth embodiment]
A sixth embodiment of the present invention will be described. In the electroacoustic transducer (not shown) of the present embodiment, a MEMS actuator (micro electro mechanical system) is used for the piezoelectric element 120, and the configuration other than the piezoelectric element 120 is the first embodiment. It is the same.

  The MEMS actuator has the configuration shown in FIG. As for the MEMS actuator, there are methods using electrostatic force, electromagnetic force, piezoelectric effect, and thermal strain, and any method can be used, but in this embodiment, a method using the piezoelectric effect is used.

  In the figure, the MEMS actuator includes a piezoelectric thin film layer 125, an upper movable electrode layer 126, and a lower movable electrode layer 127. Similar to the first embodiment, this is a mechanism for generating vibration amplitude due to the piezoelectric effect, and is a mechanism for generating vibration amplitude by inputting an AC signal to the electrode layer.

  In addition, although the method of blowing a solid molten particle to the electrode layers 126 and 127 using the aerosol deposition method etc. is mentioned for manufacture of a MEMS actuator, a manufacturing method in particular is not limited.

  When the aerosol deposition method is used, since the piezoelectric film can be easily adsorbed to a substrate such as a curved surface, the degree of freedom of the shape of the piezoelectric element 120 is increased, which is useful for improving the characteristics of the electroacoustic transducer.

[Example]
The characteristic evaluation of the electroacoustic transducer of the present invention was performed using evaluation items 1 to 3 below.

  (Evaluation 1) Measurement of frequency characteristics of sound pressure level: The sound pressure level when an AC voltage of 1 V was input was measured with a microphone placed at a position away from the element by a predetermined distance. The predetermined distance is 10 cm unless otherwise specified, and the frequency measurement range is 10 Hz to 10 kHz.

  (Evaluation 2) Drop impact test: A mobile phone equipped with an electroacoustic transducer was naturally dropped 5 times from directly above 50 cm, and a drop impact stability test was performed. Specifically, breakage such as cracks after the drop impact test was visually confirmed, and the sound pressure characteristics after the test were further measured. As a result, the sound pressure level difference (referring to the difference between the sound pressure level before the test and the sound pressure level after the test) was less than 3 dB, and 3 dB or more was rated as x.

[Example 1]
The characteristics of the electroacoustic transducer described in the first embodiment of the present invention were evaluated. The evaluation results are as follows.
Sound pressure level (1 kHz): 93 dB
Sound pressure level (3 kHz): 90 dB
Sound pressure level (5 kHz): 90 dB
Sound pressure level (10 kHz): 88 dB
Drop impact stability: ○

  As is clear from the above results, according to the electroacoustic transducer of this embodiment, the frequency characteristics of the sound pressure level are flat and the sound volume is high. Further, it was demonstrated that the fundamental resonance frequency is 1 kHz or less, the vibration amplitude is large, and the sound pressure level exceeds 80 dB in a wide frequency band of 1 to 10 kHz.

[Comparative Example 1]
As Comparative Example 1, an existing electrodynamic electroacoustic transducer was manufactured (not shown).
〔result〕
Sound pressure level (1 kHz): 77 dB
Sound pressure level (3 kHz): 75 dB
Sound pressure level (5 kHz): 76 dB
Sound pressure level (10 kHz): 97 dB
Flatness of frequency characteristics of sound pressure level: ×
Drop impact stability: ×

  As is clear from the above results, according to the electroacoustic transducer of this comparative example, the frequency characteristics of the sound pressure level are not flat and the sound volume is low. In addition, it was proved that the vibration amplitude is small and a sound pressure level exceeding 80 dB cannot be realized in a wide frequency band of 1 to 10 kHz.

[Example 2]
As Example 2, the electroacoustic transducer of the second embodiment was created.
〔result〕
Sound pressure level (1 kHz): 94 dB
Sound pressure level (3 kHz): 95 dB
Sound pressure level (5 kHz): 93 dB
Sound pressure level (10 kHz): 90 dB
Drop impact stability: ○

  As is apparent from the above results, according to the electroacoustic transducer of the present embodiment, it has the same characteristics as those of the first embodiment, and the frequency characteristics of the sound pressure level are flat.

[Example 3]
As Example 3, the electroacoustic transducer of the third embodiment was created.
〔result〕
Sound pressure level (1 kHz): 90 dB
Sound pressure level (3 kHz): 91 dB
Sound pressure level (5 kHz): 88 dB
Sound pressure level (10 kHz): 87 dB
Drop impact stability: ○
As is apparent from the above results, according to the electroacoustic transducer of the present embodiment, it has the same characteristics as those of the first embodiment, and the frequency characteristics of the sound pressure level are flat.

[Example 4]
As Example 4, an electroacoustic transducer according to the fifth embodiment was created.
〔result〕
Sound pressure level (1 kHz): 92 dB
Sound pressure level (3 kHz): 90 dB
Sound pressure level (5 kHz): 88 dB
Sound pressure level (10 kHz): 91 dB
Drop impact stability: ○
As is apparent from the above results, according to the electroacoustic transducer of the present embodiment, it has the same characteristics as those of the first embodiment, and the frequency characteristics of the sound pressure level are flat.

[Example 5]
As Example 5, an electroacoustic transducer according to the sixth embodiment was produced.
〔result〕
Sound pressure level (1 kHz): 94 dB
Sound pressure level (3 kHz): 91 dB
Sound pressure level (5 kHz): 90 dB
Sound pressure level (10 kHz): 8 dB
As is apparent from the above results, according to the electroacoustic transducer of the present embodiment, it has the same characteristics as those of the first embodiment, and the frequency characteristics of the sound pressure level are flat.

[Example 6]
As Example 6, a mobile phone as shown in FIG. 12 was prepared, and the electroacoustic transducer 100 of Example 1 was mounted in this casing. Specifically, the electroacoustic transducer 100 is attached to the inner surface of the casing of the mobile phone.

(Evaluation): The sound pressure level and the frequency characteristics were measured with a microphone placed at a position 10 cm away from the element. A drop impact test was also conducted.
〔result〕
Sound pressure level (1 kHz): 88 dB
Sound pressure level (3 kHz): 86 dB
Sound pressure level (5 kHz): 87 dB
Sound pressure level (10 kHz): 85 dB
Drop impact test: No cracks were observed in the piezoelectric element even after 5 drops, and the sound pressure level (1 kHz) measured after the test was 84 dB.

[Example 7]
As Example 7, a mobile phone as shown in FIG. 12 was prepared, and the electroacoustic transducer of Example 2 was mounted in this casing. Specifically, an electroacoustic transducer is attached to the inner surface of the casing of the mobile phone.

(Evaluation): The sound pressure level and the frequency characteristics were measured with a microphone placed at a position 10 cm away from the element.
〔result〕
Sound pressure level (1 kHz): 84 dB
Sound pressure level (3 kHz): 86 dB
Sound pressure level (5 kHz): 87 dB
Sound pressure level (10 kHz): 85 dB
Flatness of frequency characteristics of sound pressure level: ○

[Example 8]
As Example 8, a mobile phone as shown in FIG. 12 was prepared, and the electroacoustic transducer of Example 3 was mounted in this casing. Specifically, an electroacoustic transducer is attached to the inner surface of the casing of the mobile phone.

(Evaluation): The sound pressure level and the frequency characteristics were measured with a microphone placed at a position 10 cm away from the element.
〔result〕
Sound pressure level (1 kHz): 86 dB
Sound pressure level (3 kHz): 85 dB
Sound pressure level (5 kHz): 87 dB
Sound pressure level (10 kHz): 84 dB
Flatness of frequency characteristics of sound pressure level: ○

[Example 9]
As Example 9, a mobile phone as shown in FIG. 12 was prepared, and the electroacoustic transducer of Example 4 was mounted in this casing. Specifically, an electroacoustic transducer is attached to the inner surface of the casing of the mobile phone.

(Evaluation): The sound pressure level and the frequency characteristics were measured with a microphone placed at a position 10 cm away from the element.
〔result〕
Sound pressure level (1 kHz): 86 dB
Sound pressure level (3 kHz): 87 dB
Sound pressure level (5 kHz): 85 dB
Sound pressure level (10 kHz): 84 dB
Flatness of frequency characteristics of sound pressure level: ○

[Example 10]
As Example 10, a mobile phone as shown in FIG. 12 was prepared, and the electroacoustic transducer of Example 5 was mounted in this casing. Specifically, an electroacoustic transducer is attached to the inner surface of the casing of the mobile phone.

(Evaluation): The sound pressure level and the frequency characteristics were measured with a microphone placed at a position 10 cm away from the element.
〔result〕
Sound pressure level (1 kHz): 85 dB
Sound pressure level (3 kHz): 86 dB
Sound pressure level (5 kHz): 83 dB
Sound pressure level (10 kHz): 84 dB

[Example 11]
As Example 11, a laptop PC as shown in FIG. 13 was prepared, and the electroacoustic transducer of Example 1 was mounted in this casing. Specifically, an electroacoustic transducer is attached to the inner surface of the casing of the mobile phone.

(Evaluation): The sound pressure level and the frequency characteristics were measured with a microphone placed at a position 10 cm away from the element.
〔result〕
Sound pressure level (1 kHz): 84 dB
Sound pressure level (3 kHz): 83 dB
Sound pressure level (5 kHz): 86 dB
Sound pressure level (10 kHz): 85 dB

  In addition, this invention is not limited to said embodiment and Example, A various deformation | transformation is accept | permitted in the range which does not deviate from the summary. For example, in the electroacoustic transducer 100 of the above embodiment, a structure in which the narrow piezoelectric element 120 is joined to the center of the wide elastic diaphragm 110 is illustrated.

  However, like the electroacoustic transducer 200 illustrated as an oscillation device in FIG. 14, the narrow piezoelectric element 120 may be bonded to a position that is offset from the center of the wide elastic diaphragm 110 to one side.

  Moreover, in the said form, it illustrated that the main body housing 130 was formed in the frame shape opened to the up-down direction. However, the main body housing 130 may be formed in a box shape having an upper surface opening (not shown). In this case, since the sound wave is emitted only upward, the volume can be further increased.

  Furthermore, in the said form, it illustrated that the five elastic diaphragms 110 and the piezoelectric element 120 were arranged in V shape. However, three or seven or more elastic diaphragms 110 and piezoelectric elements 120 may be arranged in a V shape, or may be arranged in a W shape or a zigzag shape (none of which are shown).

  Moreover, in the said form, the some elastic diaphragm 110 and the piezoelectric element 120 were formed in the same structure, and it assumed that the same electric field was uniformly applied to each. However, the plurality of elastic diaphragms 110 and the piezoelectric elements 120 may not have the same structure (not shown), and the electric fields applied to each may be different.

  Moreover, in the said form, as shown in FIG. 11, the mobile phone, a personal computer, etc. which output an audio | voice with the electroacoustic transducer 100 etc. were illustrated as an electric equipment. However, as an electronic device, an electroacoustic transducer 100 that is an oscillation device, an oscillation drive unit that drives the electroacoustic transducer 100 to output ultrasonic waves, and an object to be measured that is oscillated from the electroacoustic transducer 100. A sonar (not shown) having an ultrasonic detection unit that detects reflected ultrasonic waves and a distance calculation unit that calculates a distance from the detected ultrasonic waves to the measurement object can also be implemented.

  Needless to say, the above-described plurality of embodiments and the plurality of modifications can be combined within a range in which the contents do not conflict with each other. In the above-described embodiment, the structure of each part has been specifically described. However, the structure and the like can be variously changed within a range that satisfies the present invention.

12 Piezoelectric elements 13a-13e Piezoelectric plates 14a-14d Electrode layer 100 Electroacoustic transducer 110 Elastic vibration plate 120 Piezoelectric element 121 Piezoelectric plate 122 Upper electrode layer 123 Lower electrode layer 125 Piezoelectric thin film layer 126 Upper movable electrode layer 127 Lower movable electrode layer 130 Main body housing 140 Resin material 200 Electroacoustic transducer CU User

Claims (10)

A plurality of elastic members having elasticity;
A plurality of piezoelectric elements that are individually bonded to at least one of the front surface and the back surface of each of the plurality of vibration members, and that vibrate in response to an electric field;
A support member that supports the plurality of vibration members at both ends in a predetermined direction,
The oscillation device in which the plurality of vibration members are spaced apart in a direction perpendicular to each other, side portions overlap in the arrangement direction, and the centers of the piezoelectric elements in the arrangement direction are arranged at positions that do not overlap adjacent vibration members.   The oscillation device according to claim 1, wherein the vibration member is formed wider than the piezoelectric element.   The oscillation device according to claim 2, wherein the piezoelectric element is arranged in the center in the arrangement direction of the wide vibrating members.   The oscillation device according to claim 2, wherein the plurality of vibration members are arranged at positions where the plurality of piezoelectric elements do not overlap in the arrangement direction.   5. The plurality of vibration members are arranged at a position where the piezoelectric element and the vibration member to which the other piezoelectric element is bonded do not overlap in the arrangement direction. 6. Oscillator.   The oscillation device according to claim 1, wherein the piezoelectric element has a laminated structure in which a plurality of ceramic layers and electrode layers are alternately formed.   The oscillation device according to any one of claims 1 to 6, wherein a frequency of an ultrasonic wave oscillated by the piezoelectric element exceeds 20 kHz.   The oscillation device according to any one of claims 1 to 7, wherein the piezoelectric element oscillates an ultrasonically modulated ultrasonic wave. An oscillation device according to any one of claims 1 to 8,
An oscillation driving means for outputting an audible sound wave to the oscillation device;
Electronic equipment having An oscillation device according to any one of claims 1 to 8,
Oscillation driving means for driving the oscillation device and outputting ultrasonic waves;
Ultrasonic detection means for detecting the ultrasonic wave oscillated from the oscillation device and reflected by the measurement object;
Distance calculating means for detecting a distance from the detected ultrasonic wave to the measurement object;
Electronic equipment having

Images