JP2011250343A - High polymer actuator and electro-acoustic transducer and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high polymer actuator which can secure a large vibrational amplitude and also can adjust a vibration frequency easily as desired.SOLUTION: A film-like high polymer electrolyte gel 1-b vibrates when an electrical field is applied thereto. Formed on a pair of principal planes of the high polymer electrolyte gel 1-b respectively is a pair of electrode layers, to which an electrical field is applied. A vibration film 1-a, cramping the high polymer electrolyte gel 1-b which has the pair of electrode layers formed respectively on its pair of principal planes, propagates vibration. Therefore, the vibration film 1-a helps to secure a large vibrational amplitude and permits a vibration frequency to be adjusted easily as desired.

Description

  The present invention relates to a polymer actuator using vibration of a polymer electrolyte gel, an electroacoustic transducer including the polymer actuator, and an electronic device including the electroacoustic transducer.

  Electrodynamic electroacoustic transducers are used as acoustic components for electronic devices such as mobile phones. This electrodynamic electroacoustic transducer is composed of a permanent magnet, a voice coil, and a diaphragm. The principle of operation is that a vibration film such as an organic film fixed to a voice coil vibrates due to the action of a magnetic circuit of a stator using a magnet to generate sound waves.

  Currently, there are various proposals for the actuator as described above. For example, there is a proposal of an actuator that autonomously vibrates a polymer electrolyte gel (Patent Document 1).

Japanese Patent Laid-Open No. 04-053399

  By the way, in recent years, the demand for portable terminals of mobile phones and laptop personal computers has increased, and there has been an increasing demand for miniaturization of electroacoustic transducers. However, the sound pressure level, which is an important enhancement amount in the acoustic performance of the electroacoustic transducer, is determined by the volume exclusion of the diaphragm against air.

  Therefore, when the electroacoustic transducer is downsized, there is a problem that the sound pressure level is lowered because the area of the radiation surface of the diaphragm is reduced. On the other hand, as means for improving the sound pressure level, there is a method of increasing the generating force of the magnetic circuit and increasing the amplitude of the diaphragm.

  However, this means requires an increase in magnetic flux density and an increase in driving current, and there is a problem that the thickness of the magnetic circuit increases due to an increase in the volume of the permanent magnet and a thickening of the voice coil. Furthermore, there are problems such as an increase in power consumption accompanying an increase in current amount.

  On the other hand, as a means for realizing a small and thin electroacoustic transducer, there is a piezoelectric electroacoustic transducer using a piezoelectric effect by piezoelectric ceramics. This piezoelectric method uses a piezoelectric effect of a ceramic material to generate a vibration amplitude by an electrostrictive action by inputting an electric signal.

  The ceramic itself, whose upper and lower layers are constrained by electrode materials, vibrates and functions as a drive source.Therefore, the number of members is small compared to a magnetic circuit composed of a large number of members such as magnets and voice coils. is there.

  However, since a ceramic material having a low internal loss is used as a vibration source, the mechanical quality factor Q tends to be higher than that of an electrodynamic electroacoustic transducer that generates an amplitude through an organic film.

  For example, the electrodynamic type is about 3 to 5 and the piezoelectric type is about 50. Since the mechanical quality factor Q indicates sharpness at the time of resonance, the summary means that in the piezoelectric electroacoustic transducer, the sound pressure is high near the fundamental resonance frequency and the sound pressure is attenuated in other bands.

  That is, in the sound pressure level frequency characteristic, there is a problem that the sound characteristic level and the valley are generated, the sound of a specific frequency is emphasized or lost, and sufficient sound quality for music reproduction or the like cannot be obtained.

  In addition, since ceramic which is a brittle material is used, the impact stability at the time of dropping is weak, and there is a problem in ensuring reliability when mounted on a small electronic device such as a mobile phone. On the other hand, there is a method in which a polymer film having piezoelectricity, for example, PVDF (polyvinylidene fluoride) is used as a vibration source.

  Since the PVDF film itself has piezoelectricity, the upper and lower main surfaces are constrained by electrodes, and an expansion / contraction motion is generated by inputting an electric signal as in the case of ceramics.

  For this reason, since it has high flexibility and high internal loss characteristics peculiar to a polymer resin, it is expected as a drive source for a high sound quality and high reliability electroacoustic transducer. However, since PVDF is a high-purity thermoplastic fluoropolymer, a precise purification step is required to obtain piezoelectricity, and it is generally recognized as an expensive material. In addition, PVDF has a problem that distortion sound is generated during sound reproduction because material linearity, that is, linear characteristics with the amount of vibration with respect to the input voltage is poor.

  For this reason, groundbreaking technology for small, large-amplitude actuators that produce high-quality, small-sized electroacoustic transducers that can replace electrodynamic electroacoustic transducers and piezoelectric electroacoustic transducers has been required. .

  Further, the actuator described in Patent Document 1 autonomously vibrates the polymer electrolyte gel as described above. For this reason, it is difficult to ensure a large vibration amplitude, and it is also difficult to adjust the vibration frequency as desired.

  The present invention has been made in view of the above-described problems, and includes a polymer actuator that can ensure a large vibration amplitude and can easily adjust the vibration frequency as desired, and the polymer actuator. An electroacoustic transducer and an electronic device including the electroacoustic transducer are provided.

  The polymer actuator of the present invention includes a membrane-shaped polymer electrolyte gel that vibrates when an electric field is applied thereto, and a pair of electrodes that are individually formed on a pair of main surfaces of the polymer electrolyte gel and to which an electric field is applied And a vibrating membrane that constrains the polymer electrolyte gel in which the pair of electrode layers are individually formed on the pair of main surfaces and propagates the vibration.

  The electroacoustic transducer of the present invention includes the polymer actuator of the present invention.

  The electronic device of the present invention includes the electroacoustic transducer of the present invention.

  In the polymer actuator of the present invention, the membrane-shaped polymer electrolyte gel vibrates when an electric field is applied. An electric field is applied to a pair of electrode layers individually formed on a pair of main surfaces of the polymer electrolyte gel. The vibration membrane that restrains the polymer electrolyte gel in which the pair of electrode layers are individually formed on the pair of main surfaces propagates the vibration. For this reason, a large vibration amplitude can be secured by the vibration film, and the frequency of vibration can be easily adjusted as desired.

1 is a schematic longitudinal sectional front view showing a structure of a polymer actuator according to a first embodiment of the present invention. It is a typical vertical front view which shows the principal part of a polymer actuator. It is a typical vertical front view which shows the structure of the polymer actuator of 2nd Embodiment. It is a typical vertical front view which shows the structure of the polymer actuator of 3rd Embodiment. It is a typical vertical front view which shows the principal part of a polymer actuator. It is a typical front view which shows the external appearance of the mobile telephone terminal which is an electronic device provided with an electroacoustic transducer. It is a typical front view which shows the external appearance of the personal computer which is an electronic device provided with an electroacoustic transducer.

[First embodiment]
A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic longitudinal front view showing the polymer actuator of the present embodiment. FIG. 2 is a schematic longitudinal sectional front view showing a main part of the polymer actuator.

  As shown in FIG. 1, the polymer actuator according to the present embodiment includes a vibrating membrane 1-a, a polymer electrolyte gel 1-b fixed to one surface of the vibrating membrane 1-a, and a vibrating membrane fixedly supported. And a lead wire 1-d for connecting electricity.

  The polymer electrolyte gel 1-b functions as a drive source that generates vibration, and the upper and lower main surfaces are constrained by electrode layers 2-a and 2-c, as shown in FIG. The polymer electrolyte gel 2-b is a material having a stimulus response characteristic with respect to an external stimulus caused by an electric field or the like.

  That is, it is a material having a function of repeatedly contracting and expanding by applying an electric field and converting electric energy into vibration energy, and oscillates vibration by the following mechanism.

  The polymer electrolyte gel 2-b is a substance containing a solvent in a network structure of a three-dimensional polymer. Its feature is that it has stimulus responsiveness to external stimuli such as salt concentration, temperature, electric field, magnetic field, and light.

  In other words, since the gel is composed of a three-dimensional network with molecules as basic units, structural changes between molecules, between polymer chains, and between microdomains can be converted into various scale forms, and these changes can be accumulated. It means that it can be converted into mechanical energy.

  By the way, examples of the electrical responsiveness of the polymer electrolyte gel include electrical contraction and electroosmosis. By contacting the electrode with a polyelectrolyte gel containing water and applying a voltage, the gel shrinks anisotropically while discharging water taken into the polymer chain, while the voltage application is stopped. Then, the gel has a function of expanding by absorbing moisture and recovering to its original size again.

  This contraction due to electrical stimulation is a phenomenon that appears in all electrolyte gels, and the electrical contraction of the ionic network in this electric field is the effect of electroosmosis of water molecules in the gel. For example, in the case of an anionic polyelectrolyte gel, when a voltage is applied, polymer ions move to the anode and counter ions move to the cathode. However, since the polymer ions are fixed, most cannot move. However, electrophoresis occurs, which is a phenomenon in which a low molecular counter ion moves to the cathode.

  That is, the counter ion reaching the electrode is canceled by the electrochemical reaction, and the hydrated water is discharged on the cathode side, and the gel shrinks. In accordance with this mechanism, contraction and expansion are repeated, and electric energy is converted into vibration energy.

ポリ（Ｎーイソプロピルアクリルアミド）（以下、ＰＮＩＰＡと略す）などが使用できる。 In the polymer actuator of the present embodiment, the polymer electrolyte gel 2-b is not particularly limited as long as it is a polymer material having stimulus responsiveness to an electric field, but as an example,

Poly (N-isopropylacrylamide) (hereinafter abbreviated as PNIPA) can be used.

  PNIPA having a hydrophobic group (isopropyl group) and a hydrophilic group (amide group) in the molecule is a general-purpose material that is widely recognized as a material having high stimulus responsiveness, and thus is advantageous in terms of cost and reliability.

  In the polymer actuator of the present embodiment, the thickness of the polymer electrolyte gel 2-b is not particularly limited, but the thickness is preferably 50 μm. When the thickness is less than 50 μm, there is a problem that an extremely unstable three-dimensional network is formed when the thickness varies and the molecular structure is constructed, and sufficient shrinkage cannot be obtained.

  Further, in order to generate an electric field in the polymer electrolyte gel 2-b of the present invention, electrode layers 2-a and 2-c are formed on the upper and lower main surfaces. The electrode material is not particularly limited as long as it has electrical conductivity, but it is preferable to use gold, silver, or silver / palladium.

  The thickness of the electrode material is not particularly limited, but is preferably 1 to 50 μm. For example, if the thickness is less than 1 μm, there is a problem that the film cannot be uniformly formed on the electrode because the film thickness is thin.

  On the other hand, when the film thickness exceeds 100 μm, molding becomes easy, but the electrode layers 2-a and 2-c serve as constraining surfaces, resulting in a problem of reducing the conversion efficiency into vibration energy. In addition, as an electrode formation method, sputtering method etc. are mentioned.

  The polymer electrolyte gel 2-b of the present invention is constrained by the vibrating membrane 1-a. For example, the vibrating membrane 1-a has a function of propagating sound waves, generates sound waves by propagating vibrations caused by contraction / expansion from the polymer electrolyte, and the polymer actuator itself has a function as an electroacoustic transducer. .

  Further, the vibrating membrane 1-a has a function of improving impact stability when dropped, and a function of adjusting the basic resonance frequency of the polymer actuator or the electroacoustic transducer. That is, since the vibration membrane 1-a is made of an elastic material, it is possible to absorb impact energy when dropped by the vibration membrane 1-a, and the impact stability of the electroacoustic transducer is improved.

Further, the basic resonance frequency of the mechanical vibrator is expressed by the following formula 1,
[Equation 1]
f = 1 / 2πL√ (m · C) Equation 1
Depends on load weight and compliance.

  In other words, since the compliance is the mechanical rigidity of the vibrator, this means that the fundamental resonance frequency can be controlled by controlling the rigidity of the vibrating membrane 1-a. For example, the fundamental resonance frequency can be shifted to a low range by selecting a material having a high elastic modulus or reducing the thickness of the material.

  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 material. It is superior in design constraints and cost without changing the basic structure.

  Since this embodiment can be easily adjusted to a desired fundamental resonance frequency by changing the elastic material as a constituent member, the industrial value is great. The vibrating membrane 1-a is not particularly limited as long as it is a material having a high elastic modulus such as an organic polymer material, but general-purpose materials such as polyethylene terephthalate, polyethylene, and polyuetane are used from the viewpoint of workability and cost. .

  The thickness of the vibration film 1-a is preferably 5 to 1000 μm. When the thickness is less than 5 μm, there is a problem that mechanical strength is weak, the function as a restraining member is impaired, and the mechanical vibration characteristics of the vibrators vary between manufacturing lots due to a decrease in processing accuracy.

  Moreover, when thickness exceeds 1000 micrometers, the restriction | limiting to the polymer electrolyte gel 2-b by increase in rigidity becomes strong, and there exists a subject which produces the attenuation | damping of a vibration displacement amount. In addition, the elastic material of the present embodiment preferably has a longitudinal elastic modulus, which is an index indicating the rigidity of the material, of 1 to 500 GPa. As described above, when the rigidity of the elastic material is excessively low or excessively high, there is a problem that the characteristics and reliability of the mechanical vibrator are impaired.

  In the present embodiment, the vibrating membrane 1-a is bonded to the support 1-c. The support 1-c serves as a case for the polymer actuator. As the material of the support 1-c, any material such as a metal, a resin, or a composite material of a metal and a resin can be used. In order to efficiently transmit vibration energy from the vibration film 1-a, A material having a certain degree of rigidity with respect to the amount of transmitted vibration is preferable.

  The operation principle of the polymer actuator of this embodiment will be described below. The polymer actuator of the present embodiment repeatedly applies and stops an electric signal to the polymer electrolyte gel 2-b, and utilizes contraction and expansion.

  As described above, by applying electrical stimulation to the polymer electrolyte gel 2-b, a reversible and continuous bending motion due to contraction / expansion occurs. It is the operating principle of the polymer actuator or electroacoustic transducer of this embodiment that propagates this bending motion to the vibrating membrane 1-a and generates vibration amplitude and sound waves.

  As described above, in the polymer actuator of the present embodiment, since the driving source is configured by the vibrating membrane 1-a and the polymer electrolyte gel 2-b, an electrodynamic electric power composed of a conventionally used magnetic circuit is used. Compared to acoustic transducers, it is superior in miniaturization.

  In the polymer actuator according to the present embodiment, when an electric field is applied as described above, the membrane-shaped polymer electrolyte gel 1-b vibrates, and a pair of electrode layers are individually formed on a pair of main surfaces. The vibrating membrane 1-a that restrains the polymer electrolyte gel 1-b that is present propagates vibration.

  For this reason, a large vibration amplitude can be secured by the vibration film 1-a. Therefore, compared with the actuator of Patent Document 1 described above, it is possible to generate a sound wave with a large volume with less power consumption. Moreover, it is easy to adjust the frequency of vibration as desired. Therefore, unlike Patent Document 1 described above, it is possible to generate sound waves having a desired scale.

  In addition, since the constituent members of the drive source are made of a resin material having a larger internal loss than metals and ceramics, the mechanical quality factor Q is lower than that of the piezoelectric electroacoustic transducer, and the flat amplitude frequency characteristics. It is advantageous in that it can be realized.

  In addition, when this polymer actuator is used as a drive source for an electroacoustic transducer, the constituent members are made of a highly flexible resin material, so that machining at the time of manufacture is easy, and the conventional manufacturing cost is also reduced. It is superior to electroacoustic transducers.

  Furthermore, since it is comprised with the resin material, it becomes advantageous also about the impact stability at the time of dropping. As described above, the polymer actuator or the electroacoustic transducer according to the present embodiment has a large industrial value because it is small in size and can realize high sound quality and can be easily mounted on a mobile phone.

  In addition, as shown in FIGS. 6 and 7, an electronic component using the polymer actuator according to the present embodiment, for example, an electroacoustic transducer, is an electronic device (for example, a mobile phone, a laptop personal computer, a small game). It can also be used as a sound source for devices. As described above, since it is small and has high sound quality and high reliability, it can be suitably used for portable electronic devices.

[Second Embodiment]
A second embodiment of the present invention will be described below with reference to FIG. The present embodiment is characterized in that an elastic member 5-e is newly arranged with respect to the first embodiment. The support 5-c and the lead wire 5-d are the same as in the first embodiment.

  That is, the elastic member 5-e is interposed between the vibrating membrane 5-a and the polymer electrolyte gel 5-b, so that adjustment to a basic resonance frequency suitable as a polymer actuator can be easily performed. .

  For example, when an electroacoustic transducer is considered, a frequency band of 100 to 20 kHz is conventionally used for reproduction such as music reproduction. For this reason, the basic resonance number of the electroacoustic transducer is adjusted to around 1 kHz in order to prevent a sound pressure level difference between the bands.

  Usually, the fundamental resonance frequency of a mechanical vibrator depends on rigidity and weightlessness as in the above-described “Equation 1”, and therefore, in the electroacoustic transducer of the present invention composed of a resin material having a small Young's modulus, In particular, there is a problem of shifting to a low frequency.

  Therefore, by interposing an elastic member between the vibrating membrane and the polymer electrolyte gel, the rigidity can be enhanced and adjustment to a desired fundamental resonance frequency can be achieved. The elastic material is not particularly limited as long as it is a material having a high Young relative to the polymer electrolyte gel, such as a metal or a resin-metal composite material, but general-purpose materials such as phosphor bronze and stainless steel from the viewpoint of workability and cost. Is used.

  The thickness of the elastic material is preferably 5 to 1000 μm. When the thickness is less than 5 μm, there is a problem that mechanical strength is weak, the function as a restraining member is impaired, and the mechanical vibration characteristics of the vibrators vary between manufacturing lots due to a decrease in processing accuracy.

  Further, when the thickness exceeds 1000 μm, there is a problem that the restraint on the piezoelectric element due to the increase in rigidity is strengthened, and the vibration displacement amount is attenuated and the basic resonance frequency is increased.

  In addition, the elastic material of the present embodiment preferably has a longitudinal elastic modulus, which is an index indicating the rigidity of the material, of 1 to 500 GPa. As described above, when the Young's modulus is excessively low or excessively high, there are problems that impair characteristics and reliability as a mechanical vibrator.

  As described above, according to the present embodiment, by interposing an elastic material between the polymer electrolyte gel and the vibration membrane, it is possible to easily adjust to a basic resonance frequency suitable for an acoustic transducer, and to produce high-quality sound. Can be played.

  In the polymer actuator configured as described above, the electromotive electroacoustic transducer composed of a magnetic circuit because the drive source is composed of a polymer electrolyte gel material that bends according to the state of the electric field. Compared to, a small converter can be realized.

  That is, since the drive source itself is made of a polymer electrolyte gel material having a high internal loss, the mechanical quality factor Q of the actuator itself is low, the amplitude peak in the vicinity of the resonance frequency is small, and the frequency amplitude characteristic width is flat without a valley. Frequency characteristics can be realized.

  In addition, since the polymer electrolyte gel having a basic structure crosslinked by a covalent bond is chemically stable, a polymer actuator using the polymer electrolyte gel as a driving source has high reliability. Furthermore, since the polymer electrolyte gel is a colloid of a solid dispersion medium in a broad sense, it has high flexibility and high viscosity, so that it has high impact stability when dropped.

  Moreover, since it is a viscous solid represented by agar, shape processing is also easy. For this reason, a high-reliability and low-cost polymer actuator can be realized. Furthermore, by using this polymer actuator as a driving source for an electronic component and an electroacoustic transducer, a small and high-quality electroacoustic transducer can be realized.

  As described above, the polymer actuator and the electroacoustic transducer according to the present embodiment are used as a sound source of an electronic device (for example, a mobile phone, a laptop personal computer, a small game device, etc.) as shown in FIGS. Is also available. Since the overall shape of the electroacoustic transducer is not significantly increased and the acoustic characteristics are improved, the electroacoustic transducer can be suitably used for a portable electronic device.

[Third embodiment of the present invention]
A third embodiment of the present invention will be described below with reference to FIG. In the polymer actuator of the present embodiment, the two polymer electrolyte gels 6-b1 and 6-b2 restrain the upper and lower main surfaces of the vibrating membrane 6-a. The support 6-c and the lead wire 6-d are the same as in the first embodiment.

  That is, the vibration amount of the vibrating membrane 6-a is amplified by utilizing the bending motion of the two polymer electrolyte gels 6-b1 and 6-b2. In the polymer actuator of the present embodiment, the two polymer electrolyte gels 7-b1, 7- are driven as shown in FIG. 5 by driving the polymer electrolyte gels 6-b1, 6-b2 to be in phase. The vibration generated from b2 interferes, and the vibration amount of the vibration film 7-a is amplified.

  Therefore, the present embodiment is advantageous in that the amount of vibration can be increased without significantly increasing the shape of the vibrator. As described above, the polymer actuator and the electroacoustic transducer according to the present embodiment are used as a sound source of an electronic device (for example, a mobile phone, a laptop personal computer, a small game device, etc.) as shown in FIGS. Is also available. Since the overall shape of the electroacoustic transducer does not increase and the acoustic characteristics are improved, the electroacoustic transducer can be suitably used for a portable electronic device.

Embodiment 1 of the Invention
In order to demonstrate the effect of the polymer actuator of the present invention, electroacoustic transducers of the following examples were prepared, and the characteristic evaluation was performed using evaluation items 1 to 3 below.

(Evaluation 1)
Measurement of sound pressure level frequency characteristics: 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)
Measurement of flatness of sound pressure level frequency characteristics: The sound pressure level at the time of input of AC voltage 1V was measured by a microphone disposed at a predetermined distance from the element. The frequency measurement range was 10 Hz to 10 kHz, and in the measurement range of 2 kHz to 10 kHz, the flatness of the sound pressure level frequency characteristic was measured by the sound pressure level difference between the maximum sound pressure level Pmax and the minimum sound pressure level Pmin.

  As a result, the sound pressure level difference (which indicates the difference between the maximum sound pressure level Pmax and the minimum sound pressure level Pmin) is within 20 dB, and is over 20 dB. This predetermined distance is 10 cm unless otherwise specified.

(Evaluation 3)
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 difference in sound pressure level (referring to the difference between the sound pressure level before the test and the sound pressure level after the test) was 3 dB or less, and 3 dB or more was evaluated as x.

[Example 1]
The characteristics of the electroacoustic transducer composed of the polymer actuator described in the first embodiment of the present invention were evaluated. The evaluation results are as follows.
〔result〕
Sound pressure level (1 kHz): 80 dB
Sound pressure level (3 kHz): 81 dB
Sound pressure level (5 kHz): 82 dB
Sound pressure level (10 kHz): 83 dB
Flatness of sound pressure level frequency characteristics: ○
Drop impact stability: ○

  As is clear from the above results, according to the electroacoustic transducer of this example, it was proved that the sound pressure level frequency characteristic is flat, a large volume reproduction is possible, and high reliability is achieved. .

[Comparative Example 1]
As Comparative Example 1, a conventional electrodynamic electroacoustic transducer was manufactured.
〔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 sound pressure level frequency characteristics: ×
Drop impact stability: ×

[Embodiment 2 of the Invention]
As Example 2, an electroacoustic transducer composed of the polymer actuator of the second embodiment was prepared.
〔result〕
Sound pressure level (1 kHz): 85 dB
Sound pressure level (3 kHz): 87 dB
Sound pressure level (5 kHz): 84 dB
Sound pressure level (10 kHz): 86 dB
Flatness of sound pressure level frequency characteristics: ○
Drop impact stability: ○
As is clear from the above results, the electroacoustic transducer of this example has the same characteristics as those of Example 1, the sound pressure level frequency characteristic is flat, and has high reliability.

Embodiment 3 of the Invention
As Example 3, an electroacoustic transducer composed of the polymer actuator of the third embodiment was created.
〔result〕
Sound pressure level (1 kHz): 87 dB
Sound pressure level (3 kHz): 91 dB
Sound pressure level (5 kHz): 88 dB
Sound pressure level (10 kHz): 86 dB
Flatness of sound pressure level frequency characteristics: ○
Drop impact stability: ○
As is clear from the above results, the electroacoustic transducer of this example has the same characteristics as those of Example 1, the sound pressure level frequency characteristic is flat, and has high reliability.

[Embodiment 4 of the Invention]
As Example 4, a mobile phone as shown in FIG. 6 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. A drop impact test was also conducted.
〔result〕
Sound pressure level (1 kHz): 81 dB
Sound pressure level (3 kHz): 82 dB
Sound pressure level (5 kHz): 84 dB
Sound pressure level (10 kHz): 80 dB
Flatness of sound pressure level frequency characteristics: ○
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.

[Embodiment 5 of the invention]
As Example 5, a mobile phone as shown in FIG. 6 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. A drop impact test was also conducted.
〔result〕
Sound pressure level (1 kHz): 81 dB
Sound pressure level (3 kHz): 84 dB
Sound pressure level (5 kHz): 87 dB
Sound pressure level (10 kHz): 83 dB
Flatness of sound pressure level frequency characteristics: ○
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 78 dB.

[Embodiment 6 of the invention]
As Example 6, a mobile phone as shown in FIG. 6 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. A drop impact test was also conducted.
〔result〕
Sound pressure level (1 kHz): 81 dB
Sound pressure level (3 kHz): 82 dB
Sound pressure level (5 kHz): 85 dB
Sound pressure level (10 kHz): 80 dB
Flatness of sound pressure level frequency characteristics: ○
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 78 dB.

[Embodiment 7 of the Invention]
As Example 7, a laptop PC (Personal Computer) as shown in FIG. 7 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. A drop impact test was also conducted.
〔result〕
Sound pressure level (1 kHz): 79 dB
Sound pressure level (3 kHz): 81 dB
Sound pressure level (5 kHz): 84 dB
Sound pressure level (10 kHz): 80 dB
Flatness of sound pressure level frequency characteristics: ○
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 78 dB.

  The present invention is not limited to the present embodiment, and various modifications are allowed without departing from the scope of the present invention. Naturally, the above-described embodiment and a plurality of examples can be combined as long as the contents do not conflict with each other. Further, in the above-described embodiments and modifications, the structure of each part has been specifically described, but the structure and the like can be changed in various ways within a range that satisfies the present invention.

1-a vibrating membrane 1-b polymer electrolyte gel 1-c support 1-d lead wire 2-a upper electrode layer 2-b polymer electrolyte gel 2-c lower electrode layer 5-a vibrating membrane 5-b high Molecular electrolyte gel 5-c support 5-d lead wire 5-e elastic member 6-a vibrating membrane 6-b1 polymer electrolyte gel 6-b2 polymer electrolyte gel 6-c support 6-d lead wire 7-a Vibration membrane 7-b1 polymer electrolyte gel 7-b2 polymer electrolyte gel

Claims (8)

A membrane-like polymer electrolyte gel that vibrates when an electric field is applied;
A pair of electrode layers individually formed on a pair of main surfaces of the polymer electrolyte gel and applied with the electric field;
A vibrating membrane for constraining the polymer electrolyte gel in which a pair of the electrode layers are individually formed on the pair of main surfaces and propagating the vibration;
A polymer actuator.   The polymer actuator according to claim 1, further comprising a support that fixes both ends of the vibration membrane.   The polymer actuator according to claim 1, wherein an elastic member is interposed between the vibration membrane and the polymer electrolyte gel.   The polymer actuator according to any one of claims 1 to 3, wherein the vibration membrane individually restrains the pair of polymer electrolyte gels on both of the pair of main surfaces.   The polymer actuator according to claim 1, wherein the vibration film is made of a resin.   The polymer actuator according to any one of claims 1 to 5, wherein the first vibrating membrane is an acoustic vibrating membrane that emits sound waves.   An electroacoustic transducer comprising the polymer actuator according to any one of claims 1 to 6.   An electronic device comprising the electroacoustic transducer according to claim 7.

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