KR20100120328A - Micro speaker made with cellulose piezo-paper - Google Patents

Micro speaker made with cellulose piezo-paper Download PDF

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KR20100120328A
KR20100120328A KR1020090039088A KR20090039088A KR20100120328A KR 20100120328 A KR20100120328 A KR 20100120328A KR 1020090039088 A KR1020090039088 A KR 1020090039088A KR 20090039088 A KR20090039088 A KR 20090039088A KR 20100120328 A KR20100120328 A KR 20100120328A
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piezoelectric
paper
cellulose
piezoelectric paper
micro speaker
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KR1020090039088A
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KR101116572B1 (en
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김재환
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인하대학교 산학협력단
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00Piezoelectric transducers; Electrostrictive transducers
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00Diaphragms for electromechanical transducers; Cones
    • H04R7/02Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/04Plane diaphragms
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2307/00Details of diaphragms or cones for electromechanical transducers, their suspension or their manufacture covered by H04R7/00 or H04R31/003, not provided for in any of its subgroups
    • H04R2307/021Diaphragms comprising cellulose-like materials, e.g. wood, paper, linen

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

PURPOSE: A micro-speaker based on a cellulose piezoelectric paper is provided to obtain the directivity of sound by forming a frame structure into a circular shape or a curved shape. CONSTITUTION: An electrode(2) is formed on both sides of a cellulose piezoelectric paper(1). Electric field is applied to the electrodes of the cellulose piezoelectric paper, and a reversed piezoelectric effect is appeared on the piezoelectric paper. The piezoelectric paper is fixed to the frame structure. Supporting structures are located on both sides of the piezoelectric paper and are fixed to the frame structure using metal(5).

Description

셀룰로오스 압전종이로 만든 초소형 스피커{Micro speaker made with cellulose Piezo-paper}Micro speaker made with cellulose piezoelectric paper {Micro speaker made with cellulose Piezo-paper}

본 발명은 셀룰로오스 압전종이로 만든 초소형 스피커에 관한 것이다.The present invention relates to a miniature speaker made of cellulose piezoelectric paper.

압전효과(Piezoelectricity)는 100여 년 전 자크(Jacques)와 피에르 퀴리(Pierre Curie)에 의해 수정 결정(Quarts crystal)에서 발견된 이후로 의료, 군사, 산업, 가전, 탐사 등 여러 분야에서 이용되어 왔다. 특히, 2차세계대전 전후로 압전 세라믹이 개발되면서 이를 응용한 기술개발은 폭넓게 진행되었으며, 대표적인 것으로 가속도 센서, 적외선 센서, 초음파 트랜스듀서, 스피커, 마이크로폰, 작동기(actuator) 소나 등이 있다. 압전효과란 압전재료에 압력이나 힘을 가하면 압전재료 표면에 전압이 발생하며 (이를“direct effect"라 칭함) 또한 반대로 전압을 가했을 때 압전재료의 크기에 따라 변형을 일으키는 현상 (이를 "converse effect"라 칭함)을 말한다. 전자의 응용예로는 마이크로폰, 진동센서, 스위치, 가속도센서가 있고 후자의 응용예로는 스피커와 작동기가 있다. 압전재료들은 또한 초전효 과(Pyroelectricity)를 가지고 있으며 이는 압전재료 주위의 온도가 변할 경우 이에 비례해서 압전재료 표면에 전압이 발생하는 것을 말한다.Piezoelectricity has been used in medical, military, industrial, consumer electronics, and exploration fields since it was discovered in quartz crystals by Jacques and Pierre Curie over 100 years ago. . In particular, as piezoelectric ceramics were developed before and after World War II, the development of technology applied to them was widely progressed, and representative examples include acceleration sensors, infrared sensors, ultrasonic transducers, speakers, microphones, and actuator sonars. The piezoelectric effect is a phenomenon in which a pressure or force is applied to the piezoelectric material to generate a voltage on the surface of the piezoelectric material (called a "direct effect"), and conversely, a deformation occurs depending on the size of the piezoelectric material when a voltage is applied (this is called a "converse effect"). The former applications include microphones, vibration sensors, switches, and acceleration sensors, while the latter applications include speakers and actuators.Piezoelectric materials also have pyroelectricity, which is piezoelectric. When the temperature around the material changes, it means that the voltage is generated on the surface of the piezoelectric material.

이러한 압전효과를 가진 재료로서 압전세라믹과 압전폴리머가 있다. 압전세라믹은 1940년대에 바륨-티타늄 산화물 (BaTiO3)의 압전세라믹이 개발되었고 1950년대에는 납-지르코늄-티타늄의 산화물 (Lead-Zirconate-Titanate, PZT)의 압전세라믹이 개발되면서 본격적으로 연구되기 시작하였다. 압전세라믹은 단단하고 조밀한 구조로 되어 있어 화학적으로 불활성이며 습기나 여러 온도에 내환경성이 있으며, 기계적으로나 전기적으로 정확한 배열성을 갖는 장점이 있으나 세라믹 자체의 취성이 있고 무거우며 휘어지지 않는 단점이 있다. 특히 납성분이 첨가되므로 인체유해성에 대한 논란이 있어서 납을 사용하지 않는 새로운 압전세라믹에 대한 연구가 진행되고 있다. 압전폴리머는 1969년 가와이(Kawai)에 의해 polyvinylidene fluoride (PVDF)에 압전성이 있는 것이 발견되면서 개발되기 시작하였다. 압전폴리머는 얇은 엔지니어링 플라스틱으로서 그 가공이 다른 센서소재보다 간단할 뿐만 아니라 유연성이 있고, 대면적 가공이 용이하며, 충격에 강하여 깨지지 않고, 가볍고, 초음파 응용에 좋은 음향특성이 있으며, 생산성이 좋은 특성이 있다. 그럼에도, 이는 사용온도에 제한이 있으며, DC 측정에 적합하지 않으며, 압전특성이 압전세라믹보나 낮은 단점이 있다.Materials having such a piezoelectric effect include piezoceramic and piezoelectric polymers. Piezoceramics began to be studied in the 1940s with piezoceramics of barium-titanium oxide (BaTiO 3 ) and piezoceramics of lead-zirconate-titanate (PZT) in the 1950s. It was. Piezoceramic has the advantage of being chemically inert, environmentally resistant to moisture and various temperatures due to its rigid and dense structure, and having the mechanically and electrically accurate arrangement, but the weakness of the ceramic itself have. In particular, since lead is added, research on new piezoelectric ceramics that do not use lead is being conducted because there is controversy about human harmfulness. Piezoelectric polymers were developed by Kawai in 1969 when they were found to be piezoelectric in polyvinylidene fluoride (PVDF). Piezoelectric polymers are thin engineering plastics whose processing is not only simpler than other sensor materials, but also flexible, large-area processing, resistant to impact, unbreakable, lightweight, good acoustic properties for ultrasonic applications, and good productivity. There is this. Nevertheless, there is a limitation in the use temperature, it is not suitable for DC measurement, the piezoelectric characteristics of the piezoelectric ceramics, but lower disadvantages.

최근에는 셀룰로오스를 주성분으로 하는 압전종이가 개발되었는데, 압전종이는 셀룰로오스 종이의 유연성, 생분해성, 저 생산비용 및 높은 압전특성을 갖는 특 징이 있다. 셀룰로오스 펄프를 DMAc나 수산화 나트륨 등의 용매를 사용하여 녹인 셀룰로오스 용액을 박막으로 캐스팅(casting)한 후, 물과 반응을 시킴으로써 용매를 제거하여 원래의 셀룰로오스로 재생시켜 셀룰로오스 종이를 만든다. 이때 셀룰로오스 마이크로 파이버를 압출, 연신, 전기적 분극 등의 방법으로 일정한 방향으로 배열함으로서 압전성을 좋게 하며 탄소나노튜브를 셀룰로오스 용액에 섞어서 압전종이의 압전성을 향상시키기도 한다. 이와 같이 제조된 압전종이는 제조가격이 싸고 인체에 무해하며 생분해성이 없으므로 산업폐기물이 발생하지 않는 장점이 있다. Recently, piezoelectric papers based on cellulose have been developed. Piezoelectric papers are characterized by the flexibility, biodegradability, low production cost, and high piezoelectric properties of cellulose paper. A cellulose solution obtained by dissolving cellulose pulp using a solvent such as DMAc or sodium hydroxide is cast into a thin film, and then reacted with water to remove the solvent to regenerate the original cellulose to make a cellulose paper. At this time, by aligning the cellulose microfibers in a predetermined direction by extrusion, stretching, electrical polarization, etc., the piezoelectricity is improved, and the carbon nanotubes are mixed with the cellulose solution to improve the piezoelectricity of the piezoelectric paper. The piezoelectric paper manufactured as described above has an advantage that industrial waste does not occur because the manufacturing price is low, it is harmless to the human body, and is not biodegradable.

기존의 스피커는 대부분 영구자석과 코일이 들어가 있는 전동형(electrodynamic type) 스피커를 사용하고 있다. 전동형 스피커는 부피가 크기 때문에 박형화 추세에 있는 휴대폰의 구조에 어려움이 있다. 그러나 압전재료를 이용한 초소형 스피커는 박형화 할 수 있을 뿐만 아니라 소비전력을 줄일 수 있는 장점이 있어 선진 업체들에서 개발이 활발하게 진행되고 있다. 국내 Fils사 에서는 2006년 압전고분자(PVDF)에 탄소나노튜브로 투명전극을 입힌 필름 스피커를 개발하여 시판하고 있다. 국내 업체인 피엔아이에서는 PVDF에 전도성박막을 입히는 기술을 이용한 필름스피커 특허을 갖고 있으며 시제품을 최근에 개발한 바 있다. PVDF 제조사인 미국 MSI에서는 압전폴리머 스피커를 이미 1990년대에 개발하였다. 미국 SRI사에서는 유전탄성체 고분자(Dielectric elastomer)를 이용하여 고분자스피커를 시연한 바 있다. 최근에는 영국 Warwick대학에서 박판의 유연한 스피커를 개발하였다. 도체 및 절연체 박막을 적층해서 만든 이 "Flat, Flexible Loudspeaker"는 지 향성과 소리 재현성이 높고 가격이 저렴하다. 현재 Warwick Audio Technology라는 회사를 통해 상품화를 진행하고 있다. 이 외에도 일본의 마쓰시다, 미국의 Magnepan등의 회사에서 필름 스피커를 개발하고 있다. Most of existing speakers use electrodynamic type speakers with permanent magnets and coils. Electric loudspeakers are bulky and have difficulty in the construction of mobile phones, which are becoming thinner. However, micro-speakers using piezoelectric materials are not only thin, but also have the advantage of reducing power consumption. In 2006, Fils, Korea, developed and marketed a film speaker with a transparent electrode coated with carbon nanotubes on a piezoelectric polymer (PVDF). P & I, a Korean company, has a patent for a film speaker using a technology for coating a conductive thin film on PVDF, and has recently developed a prototype. MSI, a PVDF manufacturer, developed piezoelectric polymer speakers in the 1990s. US SRI demonstrated a polymer speaker using a dielectric elastomer. Recently, the University of Warwick, England, developed thin flexible speakers. The "Flat, Flexible Loudspeaker", made by stacking conductor and insulator thin films, offers high directivity, sound reproducibility, and low cost. It is currently being commercialized through a company called Warwick Audio Technology. In addition, companies such as Matsushita of Japan and Magnepan of the United States are developing film speakers.

휴대폰용 초소형 스피커는 MEMS 기술을 적용한 AlN, ZnO 박막을 이용하여 초소형 스피커를 만든 바 있으며, PMN-PT의 단결정 압전재료를 이용하여 초소형 스피커를 만들기도 했다. 이러한 초소형 스피커는 반도체 박막공정을 이용하므로, 물질의 특성이 일정하지 않으며, 가격이 비싸고 내구성이 약한 문제가 있다. The miniature speaker for mobile phones has been made by using AlN and ZnO thin films using MEMS technology, and also made a miniature speaker using PMN-PT single crystal piezoelectric material. Since such a micro speaker uses a semiconductor thin film process, the characteristics of the material are not constant, and there is a problem that the price is high and the durability is weak.

본 발명은 상술한 종래의 문제점을 해결하기 위하여 안출한 것으로서, 본 발명의 목적은 압전성이 우수하고, 생분해성이 있어서 산업폐기물을 발생시키지 않으며, 유연하고, 낮은 전압에도 큰 변형을 일으키고, 저에너지 소모, 빠른 응답성 및 저렴한 제조가격을 가지는 압전종이를 이용한 초소형 스피커를 제공하는 데 있다.The present invention has been made to solve the above-mentioned conventional problems, the object of the present invention is excellent piezoelectricity, biodegradability does not generate industrial waste, flexible, causing large deformation even at low voltage, low energy consumption To provide a compact speaker using piezoelectric paper having fast response and low manufacturing cost.

상기한 본 발명의 목적을 위해, 유연성, 생분해성, 저 생산비용 및 높은 압전특성을 갖는 압전종이의 양면에 전극을 입히고 이를 지지구조물로 고정함으로써 전기장을 가할 경우 압전종이에서 음이 발생하도록 하며, 압전종이 초소형 스피커 요소를 프레임 구조물에 다수 설치하여 음의 스테레오화 또는 음의 지향성을 향상시키도록 하였다.For the purposes of the present invention, by applying electrodes to both sides of the piezoelectric paper having flexibility, biodegradability, low production cost and high piezoelectric properties and fixing it with a support structure, so that the sound is generated in the piezoelectric paper when applying an electric field, A large number of piezoelectric paper miniature speaker elements are installed in the frame structure to improve stereo or sound directivity.

압전종이로 만든 초소형 스피커는 박형으로 만들 수 있으므로 배열화 하여 여러 곳에서 음을 내는 스테레오 음향이 가능하며, 프레임 구조물을 원형 또는 곡면으로 하면 음의 지향성을 줄 수 있다. 압전종이는 셀룰로오스로 되어 있으므로 제조단가가 싸고 생분해성과 생적합성이 있어 환경친화적이다. 그리고 셀룰로오스 압전종이는 기존의 PVDF 압전고분자보다 사용온도가 비교적 높다 (~140˚C).Micro-speakers made of piezoelectric paper can be made thin so that they can be arranged in stereo sound to be produced in various places, and if the frame structure is circular or curved, the sound can be directed. Since piezoelectric paper is made of cellulose, it is environmentally friendly due to its low manufacturing cost and biodegradability and biocompatibility. In addition, the cellulose piezoelectric paper has a higher use temperature than the conventional PVDF piezoelectric polymer (~ 140˚C).

본 발명의 상술한 목적과 여러 가지 장점은 이 기술분야에 숙련된 사람들에 의해 후술되는 발명의 바람직한 실시예로부터 더욱 명확하게 이해될 것이다.The above objects and various advantages of the present invention will be more clearly understood from the preferred embodiments of the invention described below by those skilled in the art.

셀룰로오스 압전종이는 종이 양면에 전극을 입히고 전기장을 가하면 역압전효과에 의해 전기장에 따라 떨림을 발생시킨다. 도 1은 압전종이 초소형 스피커의 개략도를 나타낸 것으로서, 그 구성은 전극(2)을 입힌 압전종이(1)를 지지구조물에 고정한 형태로서 크기가 작은 박형으로 만들 수 있다. 압전종이(1)에 전극을 입히는 작업은 열증착기(Thermal Evaporator)를 사용하여 은이나 알루미늄의 전극을 입히고 내부식성을 좋게 하기 위해 니켈이나 크롬을 얇게 올린다. 또는 ITO나 탄소나노튜브 복합재를 사용하여 투명전극을 입힐 수도 있다. 압전종이는 프레임 구조물(4)에 고정하되, 간격을 유지하기 위해 지지구조물(3-1) 위에 압전종이(1)를 또 다른 지지구조물(3-2)로 눌러서 고정한다. 이렇게 압전종이를 사이에 둔 지지구조물은 프레임 구조물(4)에 리벳과 같은 금속(5)으로 고정하여 압전종이 양면에 입혀진 전극과 연결되도록 한다. 압전종이를 지지구조물에 고정할 때 압전종이가 늘어나지 않도록 팽팽한 상태로 고정시키며 이를 유지할 수 있도록 지지구조물 간에 요철을 형성한다(도 2). 지지구조물(3-1, 3-2)은 절연체로서 원형, 사각형, 육각형, 팔각형의 모양을 할 수 있다. 도 1에 나타낸 바와 같이, 프레임 구조물(4)에 초소형 스피커 요소를 배열하여 음의 스테레오화와 지향성을 갖는 스피커를 만들 수 있 다 (도 3 참조). 이때 전극의 연결을 위해 프레임 구조물(4)의 뒷면에 버스 라인 (bus line, 6) 2개를 설치하여 각 초소형 스피커 요소의 두 전극을 이들에 연결함으로써 서로 겹치지 않도록 한다. 지지구조물(3-1, 3-2) 사이에 고정된 압전종이(1)의 두 전극(2)은 지지구조물에 비어 홀 (via-hole)을 뚫어서 금속 리벳으로 고정함으로써 두 전극이 버스 라인에 연결되도록 할 수도 있고, 비어 홀을 납으로 메워서 두 전극을 버스 라인에 연결할 수도 있다. Cellulose piezoelectric paper shakes depending on the electric field due to the reverse piezoelectric effect when an electrode is applied to both sides of the paper and an electric field is applied. Figure 1 shows a schematic diagram of a piezoelectric paper miniature speaker, the configuration of the piezoelectric paper (1) coated with an electrode (2) is fixed to the support structure can be made small in size. The electrode coating on the piezoelectric paper (1) is a thermal evaporator (Thermal Evaporator) to coat the electrode of silver or aluminum and to raise a thin nickel or chromium to improve the corrosion resistance. Alternatively, transparent electrodes may be coated using ITO or carbon nanotube composites. The piezoelectric paper is fixed to the frame structure 4, but the piezoelectric paper 1 is pressed onto the supporting structure 3-1 with another supporting structure 3-2 to maintain the gap. The support structure sandwiching the piezoelectric paper is fixed to the frame structure 4 with a metal 5 such as a rivet so that the piezoelectric paper is connected to electrodes coated on both sides. When the piezoelectric paper is fixed to the support structure, the piezoelectric paper is fixed in a taut state so that the piezoelectric paper is not stretched, and irregularities are formed between the support structures to maintain it (FIG. 2). The support structures 3-1 and 3-2 may be insulated, and may have a circular, rectangular, hexagonal, or octagonal shape. As shown in FIG. 1, the micro speaker element can be arranged in the frame structure 4 to create a speaker having stereophonic sound and directivity (see FIG. 3). In this case, two bus lines 6 are installed on the rear surface of the frame structure 4 to connect the electrodes so that the two electrodes of each micro speaker element are connected thereto so as not to overlap each other. The two electrodes 2 of the piezoelectric paper 1 fixed between the supporting structures 3-1 and 3-2 are drilled via metal holes in the via structures to fix the two electrodes to the bus line. Connections can be made, or via holes can be filled with lead to connect two electrodes to the bus line.

후면 구조물에는 스피커의 후압(back pressure)을 맞춰주기 위해 공기통로를 작게 만든다. 스피커의 크기는 10mm 미만으로 작기 때문에, 도 3에 나타낸 바와 같이, 프레임 구조물에 여러 개를 설치하여 음을 여러 곳에서 발생시킬 수도 있다. 프레임 구조물은 평면뿐만 아니라, 곡면 또는 원형으로 하여 음의 지향성을 좋게 할 수도 있다. The rear structure makes the air passages small to match the back pressure of the speakers. Since the size of the speaker is less than 10mm, as shown in FIG. 3, the sound may be generated at various places by installing several pieces in the frame structure. The frame structure may be not only flat but also curved or circular to improve negative directivity.

도 1은 본 발명에 따른 압전종이 초소형 스피커 요소의 개략도,1 is a schematic diagram of a piezoelectric paper mini speaker element according to the present invention;

도 2는 압전종이가 늘어나지 않고 팽팽한 상태로 유지되도록 요철이 지지구조물 사이에 형성된 것을 나타낸 단면도, 및2 is a cross-sectional view showing that the unevenness is formed between the support structures so that the piezoelectric paper is kept in tension without stretching; and

도 3은 프레임 구조물에 다수의 초소형 스피커 요소를 배열한 상태를 나타낸 예시도이다.3 is an exemplary view illustrating a state in which a plurality of micro speaker elements are arranged in a frame structure.

Claims (4)

압전종이 양면에 금속 박막을 입혀 전극을 형성하고, 이러한 압전종이를 요철이 형성된 두 지지구조물 사이에 끼워서 프레임 구조물과 평행을 이루도록 장력을 유지시켜 고정한 구조로 구성된 셀룰로오스 압전종이로 만든 초소형 스피커.An ultra-small speaker made of cellulose piezoelectric paper composed of a structure in which a piezoelectric paper is coated with a metal thin film on both sides to form an electrode, and the piezoelectric paper is sandwiched between two unsupported support structures to maintain tension to parallel to the frame structure. 제 1 항에 있어서, 압전종이를 잡아주는 지지구조물이 사각형, 오각형, 육각형, 팔각형, 또는 원형으로 구성된 셀룰로오스 압전종이로 만든 초소형 스피커.The micro speaker of claim 1, wherein the support structure for holding the piezoelectric paper is made of cellulose piezoelectric paper composed of a square, a pentagon, a hexagon, an octagon, or a circle. 제 1 항 또는 제 2 항에 있어서, 압전종이 초소형 스피커 요소를 평면 또는 곡면의 프레임 구조물에 다수 설치하여 음의 입체성 및 지향성을 향상시키도록 구성된 셀룰로오스 압전종이로 만든 초소형 스피커.3. The micro speaker of claim 1 or 2, wherein the piezoelectric paper is made of cellulose piezoelectric paper, which is configured to install a plurality of micro speaker elements in a flat or curved frame structure to improve sound dimensionality and directivity. 제 1 항에 있어서, 전극이 ITO 또는 탄소나노튜브 복합재료로 이루어진 투명전극으로 구성된 셀룰로오스 압전종이로 만든 초소형 스피커.The micro speaker of claim 1, wherein the electrode is made of cellulose piezoelectric paper composed of a transparent electrode made of ITO or carbon nanotube composite material.
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