EP0582557A2 - Membran piézo-électrique contrainte au centre et son utilisation comme hurleur - Google Patents

Membran piézo-électrique contrainte au centre et son utilisation comme hurleur Download PDF

Info

Publication number
EP0582557A2
EP0582557A2 EP93830348A EP93830348A EP0582557A2 EP 0582557 A2 EP0582557 A2 EP 0582557A2 EP 93830348 A EP93830348 A EP 93830348A EP 93830348 A EP93830348 A EP 93830348A EP 0582557 A2 EP0582557 A2 EP 0582557A2
Authority
EP
European Patent Office
Prior art keywords
loading plate
piezomembrane
howler
acoustic
fact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93830348A
Other languages
German (de)
English (en)
Other versions
EP0582557A3 (fr
Inventor
Massimo Brachi
Nicola Lamberti
Massimo Pappalardo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
IMAPO Srl
Original Assignee
IMAPO Srl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by IMAPO Srl filed Critical IMAPO Srl
Publication of EP0582557A2 publication Critical patent/EP0582557A2/fr
Publication of EP0582557A3 publication Critical patent/EP0582557A3/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/122—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using piezoelectric driving means

Definitions

  • This invention relates to a piezoelectric transducer and in particular to the use one may do of it, to provide an acoustic howler.
  • piezoelectric transducers find a large employment as telephone transmitters and as acoustic howlers, well-known as "buzzers".
  • Piezoelectric transducers offer several advantages over the traditional ones based on magnetodynamic and electrodynamic effect. In fact they are basically voltage drived and offer a higher electric impedance, furthermore the absence of magnets and copper-wire coils, allows a much lower weight and a lower cost.
  • the most common embodyment of piezoelectric transducer comprises the employment of a piezomembrane formed by a thin metal disk constrained along its external circumference on which a disk of piezoelectric ceramic is overlapped and closely connected; this disk is also quite thin.
  • Piezoelectric ceramic disk tends, by means of two electrodes connected to its main surface, to oscillate in its radial mode contracting and expanding its diameter when an alternating voltage is applied to it. Ceramic disk radial expansion is opposed by the metal disk. Internal stresses owed to ceramic are not symmetric as regards the ceramic and metal interface plane and therefore the membrane is subjected to flexural stresses such as to what happens in the case of a bimetal subjected to temperature changes.
  • the piezomembrane oscillates basically in a flexional mode presenting resonances frequencies which vary according to the elasticity modules of the metal and of the piezoceramic, the geometric sizes and the type of constraint.
  • the transducer is designed so that it has the first, and in some cases, also the second resonance frequency in the bands of interest (100-5000 Hz). Flat enough band are obtained by using one or more resonating cavities coupled with the membrane.
  • the type of constraint affects the resonance frequency of the piezoceramic.
  • a yielding constraint allows to lower advantageously the frequency, radius being equal, but since in practice this constraint is obtained by coupling cords of elastomers which unavoidably dissipate elastic energy, the type of constraint determines after all not only the resonance frequency but also the acoustic efficiency of the piezomembrane.
  • the aforesaid objects are obtained by means of a pin passing through the center of a plate of plastic material (loading plate), which in turn, is constrained along the external circumference.
  • the piezomembrane behaves like a generator of vibromotive force while the plate, which oscillates due to the piezoelectric membrane, is the means by wich acoustic energy is irradiated by air coupling.
  • the first symmetric resonance mode of said piezomembrane corresponds to a frequency of about 1300 Hz, quite in the middle of the telephonic band.
  • the second flexional mode corresponds to a frequency of about 5080 Hz and therefore out of the efficient band.
  • the piezomembrane coupled to the plastic plate by means of the central pin, constitutes an oscillating system which shows, in the band of interest besides its resonance frequencies, also the one of the plate (about 1600 Hz). The frequencies change a little due to modes coupling.
  • the related system has been observed by means of node analysis with ANSYS calculus code, which uses finite-element method.
  • Fig. 4 shows deformed lines of a sector of the related system, 10° large with reference to the first three resonance modes previously pointed out by means of the impedance diagram.
  • the figure refers to the case where the piezoceramic is external to the constraint structure, contrarily the case of Fig. 1; however this difference does not change the results, as it is easy to realise.
  • the piezoceramic oscillates basically as it were rigidly constrained in the center in its first symmetric mode; anyway it is also able to let the plastic loading plate oscillate, which vibrates without presenting nodal circles and reverse phase areas.
  • the piezomembrane has two nodal circles likewise what, would happen in the second symmetric mode if it was rigidly constrained in the center; also in this case the loading plate has no noxious nodal circles. It's possible to predict the resonance frequencies of the system either by means of the aforesaid simulation method or by suitable equivalent circuits. The advantages of such a system are various, compared with what concerns the system of the membrane constrained on the rim. First of all, from the point of view of the design the system has three resonance modes in the efficiency band, with deformed lines of the loading plate without nodal circles and therefore potentially with high efficiency.
  • the piezomembrane constrained on the rim has its second symmetric mode also in the band; however without a nodal circle, only if its diameter is > 40mm.
  • the constraint in the center dissipates much less elastic energy and it's simplyer to construct; it does not need the employment of elastomers, glues or elastic seals, and it's substantially cheaper and makes it possible to carry out at the same time electric connections, as it will be seen in the next paragraph.
  • an acoustic howler has been built, the technical drawing of which is represented in Fig. 5.
  • the loading plate is considered to be 0.47 mm thick and to have a diameter of 43 mm (Fig. 5). It is integrant part of the howler casing and the employed piezomembrane is the one previously described.
  • the loading plate has a pin joint therewith, inside and at the center of the casing, which makes the piezoceramic to be fixed. In fact said piezoceramic after having been perforated is fixed on the pin by means of cold rivetting or by means of ultrasonic welding.
  • the casing and therefore the loading plate are mold in ABS by means of thermoplastic technique.
  • the casing cover is mold in ABS; it's formed by a disk which hasaa hole in the center.
  • the cover is fixed at the bottom of the casing by means of ultrasonic welding.
  • the cover hole, together with the air volume contained in the casing, provides a resonant cavity which produces a further resonance with respect to the aforesaid resonances of the piezomembrane - loading plate system.
  • the section of said loading plate is slightly conical, this is in order to increase its crosswise rigidity and to avoid noxious, not symmetric deformations of the plate.
  • the electric contacts of the piezoceramic are made by means of nickel silver springs, which have a buttonhole fitting in the loading plate pin (Fig. 6).
  • the piezomembrane which has a hole in the center, as it has been said, is inserted on the pin between the two springs; after the rivetting, said springs assure a good electric contact with the metal plane.
  • a good electric insulation between the two electrodes of the piezoceramics is assured, being the pin of ABS.
  • Springs are constrained to the casing by means of suitable placings, and they lean out of said casing in order to provide the electric terminal of the transducer. Electroacoustic characteristics of the howler are showed in Tab. I, while in Tab.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Transducers For Ultrasonic Waves (AREA)
EP93830348A 1992-08-05 1993-08-03 Membran piézo-électrique contrainte au centre et son utilisation comme hurleur. Withdrawn EP0582557A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITRM920591A IT1262971B (it) 1992-08-05 1992-08-05 Piezomembrana vincolata al centro e suo impiego per la realizzazione di avvisatore acustico.
ITRM920591 1992-08-05

Publications (2)

Publication Number Publication Date
EP0582557A2 true EP0582557A2 (fr) 1994-02-09
EP0582557A3 EP0582557A3 (fr) 1995-01-18

Family

ID=11401146

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93830348A Withdrawn EP0582557A3 (fr) 1992-08-05 1993-08-03 Membran piézo-électrique contrainte au centre et son utilisation comme hurleur.

Country Status (2)

Country Link
EP (1) EP0582557A3 (fr)
IT (1) IT1262971B (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0930607A2 (fr) * 1998-01-13 1999-07-21 Murata Manufacturing Co., Ltd. Capteur à ultrason
US7359286B2 (en) * 2006-05-03 2008-04-15 Esaote S.P.A. Multi-level capacitive ultrasonic transducer
JP2019220911A (ja) * 2018-06-22 2019-12-26 株式会社トーキン 超音波センサ
US10847708B2 (en) 2014-07-11 2020-11-24 Microtech Medical Technologies Ltd. Multi-cell transducer

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3029067A1 (de) * 1980-07-31 1982-02-11 Bolta-Werke Gmbh, 8561 Diepersdorf Vorrichtung zur schallerzeugung, insbesondere fuer weck- oder alarmeinrichtungen
EP0053947A1 (fr) * 1980-12-10 1982-06-16 Matsushita Electric Industrial Co., Ltd. Transducteur ultrasonique

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3029067A1 (de) * 1980-07-31 1982-02-11 Bolta-Werke Gmbh, 8561 Diepersdorf Vorrichtung zur schallerzeugung, insbesondere fuer weck- oder alarmeinrichtungen
EP0053947A1 (fr) * 1980-12-10 1982-06-16 Matsushita Electric Industrial Co., Ltd. Transducteur ultrasonique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JEE JOURNAL OF ELECTRONIC ENGINEERING, vol.25, no.260, August 1988, TOKYO JP pages 62 - 66 H.NISHIYAMA & K.KAGA 'Piezoelectric sound components used in a broad range of applications' *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0930607A2 (fr) * 1998-01-13 1999-07-21 Murata Manufacturing Co., Ltd. Capteur à ultrason
EP0930607A3 (fr) * 1998-01-13 2001-11-21 Murata Manufacturing Co., Ltd. Capteur à ultrason
EP1265222A1 (fr) * 1998-01-13 2002-12-11 Murata Manufacturing Co., Ltd. Boítier pour un capteur à ultrasons constitué d'une partie cylindrique et d'un élément vibratoire
US7359286B2 (en) * 2006-05-03 2008-04-15 Esaote S.P.A. Multi-level capacitive ultrasonic transducer
US10847708B2 (en) 2014-07-11 2020-11-24 Microtech Medical Technologies Ltd. Multi-cell transducer
US11800806B2 (en) 2014-07-11 2023-10-24 Microtech Medical Technologies Ltd. Method for manufacturing a multi-cell transducer
JP2019220911A (ja) * 2018-06-22 2019-12-26 株式会社トーキン 超音波センサ

Also Published As

Publication number Publication date
EP0582557A3 (fr) 1995-01-18
ITRM920591A1 (it) 1994-02-05
IT1262971B (it) 1996-07-23
ITRM920591A0 (it) 1992-08-05

Similar Documents

Publication Publication Date Title
JP3489509B2 (ja) 電気音響変換器
CA1183937A (fr) Transducteur piezoelectrique
CA1158987A (fr) Transducteur electro-acoustique avec dome actif
AU1102183A (en) Piezoelectric transducer apparatus
CN102972046A (zh) 振荡装置和电子设备
JP2003125473A (ja) 筐体振動圧電アクチュエータ及び携帯用電子装置
JP3395672B2 (ja) 圧電型電気音響変換器
JP2003520002A (ja) 圧電フィルム音波エミッタ
JP2010074488A (ja) 音響再生装置
EP0582557A2 (fr) Membran piézo-électrique contrainte au centre et son utilisation comme hurleur
JPH0275299A (ja) 電気音響ユニット変換器
JP3202169B2 (ja) 圧電発音体
CN212115670U (zh) 压电扬声器
JP2002315098A (ja) 電気音響変換器
JP2001036993A (ja) 圧電型電気音響変換器
CN218734951U (zh) 一种受话器
CN111183654A (zh) 喇叭音响
JPS58202698A (ja) 圧電形電気音響変換器の支持構造
JPH0332958B2 (fr)
JPS6098795A (ja) 圧電型電気音響変換器
JPS6130899A (ja) 圧電スピ−カ
KR200389003Y1 (ko) 압전 세라믹스를 이용한 전자음향변환장치
JPS6221120Y2 (fr)
JP3324541B2 (ja) 円筒型送波器
JPS59174096A (ja) 圧電型トランスジユ−サ

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH DE DK ES FR GB GR IE LI LU MC NL PT SE

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): AT BE CH DE DK ES FR GB GR IE LI LU MC NL PT SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19950719