EP0354520A2 - Electroacoustic transducer - Google Patents

Electroacoustic transducer Download PDF

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Publication number
EP0354520A2
EP0354520A2 EP89114587A EP89114587A EP0354520A2 EP 0354520 A2 EP0354520 A2 EP 0354520A2 EP 89114587 A EP89114587 A EP 89114587A EP 89114587 A EP89114587 A EP 89114587A EP 0354520 A2 EP0354520 A2 EP 0354520A2
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EP
European Patent Office
Prior art keywords
bearing
electroacoustic transducer
transducer
transducer according
areas
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Granted
Application number
EP89114587A
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German (de)
French (fr)
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EP0354520A3 (en
EP0354520B1 (en
Inventor
Gerd Böhnke
Stefan Pieper
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Siemens AG
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Siemens AG
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Priority to AT8989114587T priority Critical patent/ATE104823T1/en
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Publication of EP0354520A3 publication Critical patent/EP0354520A3/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/11—Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's

Definitions

  • the invention relates to an electroacoustic transducer with a circular transducer plate arranged in a transducer housing and clamped between bearing bodies in the edge region and provided with a piezoelectric layer, in particular for telephone sets.
  • one of the tasks to be solved in the manufacture of electroacoustic transducers is to ensure that the relationship between the acoustic parameters of the sound field and the electrical variables of the transducer in the transmission range is largely frequency-independent.
  • the frequency dependency of the relationship between the parameters of the sound field and the electrical variables of the transducer is determined in particular by the frequency dependency of the vibratory mechanical structure consisting of the membrane and the coupled air spaces or the like.
  • the membranes of high quality sound receivers e.g. of condenser microphones are clamped and arranged in such a way that the resonance frequency corresponding to their fundamental vibration lies far above the frequency range of interest, so that the relationship between the deflection of the membrane and the parameters of the sound field in this frequency range is practically frequency-independent.
  • Newer piezoelectric transducers have, instead of the usual membrane, a transducer plate which is clamped between bearing bodies in their edge area and which is provided with a piezoelectric layer. If such a plate is then excited electrically or acoustically, pronounced peaks form on the plate depending on the measured sound pressure and frequency, which can be made visible by holographic interferometry and which are characterized by circular node lines and node diameters.
  • the elevations which are distinguished by the node diameter play no role.
  • the circular node lines are essential.
  • the partial vibration characterized by the 1st circular node line can be dampened by two ⁇ / 2 resonators (DE-PS 1 167 897).
  • the partial oscillation marked by the second circular node line was not dampened in the past because it did not fall within a tolerance scheme specified by the postal administrations. However, due to the expansion of the tolerance range from 8 kHz to 10 kHz, this partial oscillation led to the tolerance range being exceeded, so that it must now be damped.
  • This partial oscillation could be damped with a broadband Helmholtz resonator, which, however, can be arranged only with difficulty in the existing converter housing.
  • the object of the invention is to carry out the damping of the partial vibration characterized by two circular node lines with the simplest possible means.
  • At least one bearing area of a bearing body has a rotationally asymmetrical shape.
  • the transducer plate which vibrates with its natural frequency, generates a sound pressure level that can lie between a pronounced increase in sound pressure and a drop in sound pressure.
  • the sound pressure that arises is the result of the partial-phase vibrating partial surfaces. They each displace volumes that compensate for an effectively displaced volume. To a good approximation, the effectively displaced volume is proportional to the sound pressure.
  • the basic resonance generates the maximum sound pressure of all natural frequencies, because no sub-areas vibrate in opposite phases. If it is now possible to make the out-of-phase displaced volumes equal for ⁇ ⁇ 1, the sound pressure generated must ver dwindle (damping).
  • the modification of the converter plate bearings according to the invention has now made it possible to bring the volumes oscillating in opposite phases into the same order of magnitude.
  • the basic resonance remains relatively unaffected.
  • the invention now advantageously shows a way of avoiding complex resonators for damping partial vibrations.
  • tests can be used to determine how the rotationally asymmetrical shape of the bearing should be designed.
  • the two bearing bodies may have a rotationally asymmetrical shape and to be arranged opposite the transducer plate in such a way that the bearing areas lie opposite one another.
  • bearing body may also be expedient for the bearing body to be formed by a first concentric ring (ring-shaped extension) which splits into two partial rings in one sector.
  • the support areas can be formed by pointed bearings. To dampen the partial vibrations, it has been found that it is expedient if the bearing areas of the bearing bodies are formed by flat surfaces.
  • the bearing body are integrally formed with the housing parts.
  • the converter shown in FIG. 1 has a lower housing part 1, into which a carrier 2 is inserted.
  • a resonator ring 3 is arranged above the carrier 2.
  • the converter housing is closed by a cover 4 which has sound passage openings 5.
  • the piezoelectric layer here has electrodes, not shown, which are guided to connectors (connector 8 shown) via tapes or the like.
  • a Helmholtz resonator 9 connects the anteroom of the support 2 with the rear area and serves to dampen the basic resonance.
  • the converter plate 6 is firmly clamped in its edge area.
  • Bearing bodies are used for this purpose, which consist of cylindrical annular projections 10 to 15 of the carrier 2 and of the resonator ring 3.
  • the carrier was shown in separate figures.
  • the carrier according to FIGS. 2 and 3 was shown rotated by 180 ° in relation to the representation in FIG.
  • the support areas for the transducer plate which are formed by annular cylindrical projections, are now clearly recognizable. That's how it is initially the annular extension 16 can be seen, which splits into two partial rings 17, 18 in the left image plane.
  • the support area for the converter plate thus has a rotationally asymmetrical shape.
  • the contact area of the resonator ring is designed similarly.
  • the term resonator ring was chosen because there can be two ⁇ / 2 resonators in it.
  • the 4 shows the frequency response of the converter.
  • the ordinate means the sensitivity E in dB, the abscissa the frequency in Hertz.
  • Lines 19, 20 delimit the tolerance range between which the frequency curve is to be located.

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

Abstract

The invention relates to an electroacoustic transducer comprising a circular transducer plate (6) provided with a piezoelectric layer and arranged in a transducer housing, clamped between support bodies in the edge region. <??>It is the object to dampen higher-order partial oscillations. <??>This object is achieved by the fact that at least one rest area of a support body has a rotationally asymmetrical shape. Applicable in transducers of telephones. <IMAGE>

Description

Die Erfindung betrifft einen elektroakustischen Wandler mit einer in einem Wandlergehäuse angeordneten zwischen Lager­körpern im Randbereich eingespannten, mit einer piezoelek­trischen Schicht versehenen kreisförmigen Wandlerplatte, insbesondere für Fernsprechgeräte.The invention relates to an electroacoustic transducer with a circular transducer plate arranged in a transducer housing and clamped between bearing bodies in the edge region and provided with a piezoelectric layer, in particular for telephone sets.

Eine der bei der Herstellung elektroakustischer Wandler zu lösenden Aufgaben besteht bekanntlich darin, dafür Sorge zu tragen, daß der Zusammenhang zwischen den akustischen Be­stimmungsgrößen des Schallfeldes und den elektrischen Grö­ßen des Wandlers im Übertragungsbereich weitgehend frequenz­unabhängig ist.As is known, one of the tasks to be solved in the manufacture of electroacoustic transducers is to ensure that the relationship between the acoustic parameters of the sound field and the electrical variables of the transducer in the transmission range is largely frequency-independent.

Die Frequenzabhängigkeit des Zusammenhangs zwischen den Be­stimmungsgrößen des Schallfeldes und den elektrischen Grö­ßen des Wandlers wird insbesondere durch die Frequenzab­hängigkeit des aus der Membran und den angekoppelten Luft­räumen oder dergleichen bestehenden schwingungsfähigen mechanischen Gebildes bestimmt.The frequency dependency of the relationship between the parameters of the sound field and the electrical variables of the transducer is determined in particular by the frequency dependency of the vibratory mechanical structure consisting of the membrane and the coupled air spaces or the like.

Die Membranen hochwertiger Schallempfänger, z.B. von Kon­densatormikrofonen, sind derart eingespannt und angeordnet, daß die ihrer Grundschwingung entsprechende Resonanzfre­quenz weit oberhalb des interessierenden Frequenzbereiches liegt, so daß deshalb der Zusammenhang zwischen der Aus­lenkung der Membran und den Bestimmungsgrößen des Schall­feldes in diesem Frequenzbereich praktisch frequenzunab­hängig ist.The membranes of high quality sound receivers, e.g. of condenser microphones are clamped and arranged in such a way that the resonance frequency corresponding to their fundamental vibration lies far above the frequency range of interest, so that the relationship between the deflection of the membrane and the parameters of the sound field in this frequency range is practically frequency-independent.

Bei den elektroakustischen Wandlern der Fernsprechtechnik ist es dagegen im allgemeinen aus Gründen des Wirkungsgra­des nicht möglich, die Eigenresonanzen der Membran außer­ halb des interessierenden Frequenzbereichs zu wählen. Um dennoch die Frequenzabhängigkeit des elektroakustischen Übertragungsfaktors zu verringern, ist es üblich, derar­tige Wandler mit entsprechend abgestimmten Resonatoren auszurüsten, mit deren Hilfe Resonanzspitzen kompensiert werden.In the electroacoustic transducers of telephony technology, on the other hand, it is generally not possible for reasons of efficiency, apart from the natural resonances of the membrane to choose half of the frequency range of interest. In order nevertheless to reduce the frequency dependence of the electroacoustic transmission factor, it is common to equip such transducers with appropriately tuned resonators, with the aid of which resonance peaks are compensated for.

Neuere piezoelektrische Wandler weisen anstelle der üb­lichen Membran eine zwischen Lagerkörpern in ihrem Rand­bereich eingespannte Wandlerplatte auf, die mit einer piezoelektrischen Schicht versehen ist. Wird nun eine der­dartige Platte elektrisch oder akustisch angeregt, so bil­den sich auf der Platte in Abhängigkeit von dem gemes­senen Schalldruck und der Frequenz ausgeprägte Über­höhungen, die durch holographische Interferometrie sicht­bar gemacht werden können und sich durch Kreisknotenlinien und Knotendurchmessern auszeichnen.Newer piezoelectric transducers have, instead of the usual membrane, a transducer plate which is clamped between bearing bodies in their edge area and which is provided with a piezoelectric layer. If such a plate is then excited electrically or acoustically, pronounced peaks form on the plate depending on the measured sound pressure and frequency, which can be made visible by holographic interferometry and which are characterized by circular node lines and node diameters.

Bei zylindersymmetrischen Wandlerplatten spielen die durch Knotendurchmesser sich auszeichnenden Überhöhungen keine Rolle. Wesentlich sind jedoch die Kreisknotenlinien. So können die Eigenfrequenzen des eingangs beschriebenen Wand­lers beispielsweise folgendermaßen sein
Grundresonanz (σ = 0, h = 0): ca. 1...1,5 kHz
1. Kreisknotenlinie (σ = 1, h = 0): ca. 4 kHz
2. Kreisknotenlinie (σ = 2, h = 0): ca. 7...9 kHz
3. Kreisknotenlinie (σ = 3, h = 0): ca. 14 kHz
wobei σ die Anzahl der Kreisknotenlinien und h die Anzahl der Knotendurchmesser bedeutet.In the case of cylinder-symmetrical converter plates, the elevations which are distinguished by the node diameter play no role. However, the circular node lines are essential. For example, the natural frequencies of the transducer described at the beginning can be as follows
Basic resonance (σ = 0, h = 0): approx. 1 ... 1.5 kHz
1st circular node line (σ = 1, h = 0): approx. 4 kHz
2nd circular node line (σ = 2, h = 0): approx. 7 ... 9 kHz
3rd circular node line (σ = 3, h = 0): approx. 14 kHz
where σ is the number of circular node lines and h is the number of node diameters.

Wie eingangs bereits erwähnt, müssen diese Resonanzspitzen bedämpft werden, um einen durch einzelne Fernmeldeverwal­tungen vorgegebenen Toleranzbereich nicht zu überschreiten. So ist es beispielsweise bekannt, die Grundresonanz mit einem Helmholtzresonator um ca. 15 dB zu dämpfen (Siemens Zeitschrift 46.Jahrgang, April 72, Heft 4, Seite 207-209).As already mentioned at the beginning, these resonance peaks must be damped in order not to exceed a tolerance range specified by individual telecommunications administrations. For example, it is known to dampen the basic resonance by about 15 dB with a Helmholtz resonator (Siemens magazine 46th year, April 72, volume 4, pages 207-209).

Die durch die 1.Kreisknotenlinie gekennzeichnete Teil­schwingung kann durch zwei λ/2 Resonatoren bedämpft werden (DE-PS 1 167 897).The partial vibration characterized by the 1st circular node line can be dampened by two λ / 2 resonators (DE-PS 1 167 897).

Die durch die 2.Kreisknotenlinie gekennzeichnete Teil­schwingung wurde früher nicht bedämpft, da sie nicht in ein von den Postverwaltungen vorgegebenen Toleranzschema fiel. Aufgrund der Erweiterung des Toleranzbereiches von 8 kHz auf 10 kHz führte diese Teilschwingung jedoch zu einer Überschreitung des Toleranzbereiches, so daß sie jetzt be­dämpft werden muß.The partial oscillation marked by the second circular node line was not dampened in the past because it did not fall within a tolerance scheme specified by the postal administrations. However, due to the expansion of the tolerance range from 8 kHz to 10 kHz, this partial oscillation led to the tolerance range being exceeded, so that it must now be damped.

Eine Bedämpfung dieser Teilschwingung könnte mit einem breitbandig wirkenden Helmholtzresonator erfolgen, der je­doch nur schwer in dem vorhandenen Wandlergehäuse angeord­net werden kann.This partial oscillation could be damped with a broadband Helmholtz resonator, which, however, can be arranged only with difficulty in the existing converter housing.

Aufgabe der Erfindung ist es, die Bedämpfung der durch zwei Kreisknotenlinien gekennzeichneten Teilschwingung mit mög­lichst einfachen Mitteln durchzuführen.The object of the invention is to carry out the damping of the partial vibration characterized by two circular node lines with the simplest possible means.

Die Aufgabe wird gemäß der Erfindung dadurch gelöst, daß zumindest ein Auflagebereich eines Lagerkörpers eine ro­tationsunsymmetrische Form aufweist.The object is achieved according to the invention in that at least one bearing area of a bearing body has a rotationally asymmetrical shape.

Die mit ihrer Eigenfrequenz schwingende Wandlerplatte er­zeugt einen Schalldruckpegel, der zwischen ausgeprägter Schalldrucküberhöhung und Schalldruckeinbruch liegen kann. Der sich einstellende Schalldruck ist das Ergebnis der ge­genphasig schwingenden Teilflächen. Sie verdrängen jeweils Volumina, die sich zu einem effektiv verdrängten Volumen kompensiert. In guter Näherung ist das effektiv verdrängte Volumen proportional dem Schalldruck. Die Grundresonanz er­zeugt von allen Eigenfrequenzen den maximalen Schalldruck, weil hier keine Teilflächen gegenphasig schwingen. Gelingt es nun, für σ ≧ 1 die gegenphasig verdrängten Volumina gleich groß zu machen, so muß der erzeugte Schalldruck ver­ schwinden (Bedämpfung). Durch die Modifikation der Wandler­plattenlager gemäß der Erfindung ist es nun gelungen, die gegenphasig schwingenden Volumina in die gleiche Größenord­nung zu bringen. Die partielle Änderung der Randeinspannung bedämpft die Eigenfrequenz σ = 1 und σ = 2 um ca. 8 dB, mit nur geringfügigen Verschiebungen der Eingenfrequenzen zu höheren Werten. Die Grundresonanz bleibt relativ unbe­einflußt.The transducer plate, which vibrates with its natural frequency, generates a sound pressure level that can lie between a pronounced increase in sound pressure and a drop in sound pressure. The sound pressure that arises is the result of the partial-phase vibrating partial surfaces. They each displace volumes that compensate for an effectively displaced volume. To a good approximation, the effectively displaced volume is proportional to the sound pressure. The basic resonance generates the maximum sound pressure of all natural frequencies, because no sub-areas vibrate in opposite phases. If it is now possible to make the out-of-phase displaced volumes equal for σ ≧ 1, the sound pressure generated must ver dwindle (damping). The modification of the converter plate bearings according to the invention has now made it possible to bring the volumes oscillating in opposite phases into the same order of magnitude. The partial change in the edge clamping dampens the natural frequency σ = 1 and σ = 2 by approx. 8 dB, with only slight shifts in the natural frequencies to higher values. The basic resonance remains relatively unaffected.

Durch die Erfindung wird nun in vorteilhafter Weise ein Weg aufgezeigt, aufwendige Resonatoren zur Dämpfung von Teil­schwingungen zu vermeiden. Je nach den konstruktiven Abmes­sungen der Wandler kann man durch Versuche bestimmen, wie die rotationsunsymmetrische Form der Lagerung ausgebildet sein soll.The invention now advantageously shows a way of avoiding complex resonators for damping partial vibrations. Depending on the structural dimensions of the transducers, tests can be used to determine how the rotationally asymmetrical shape of the bearing should be designed.

So kann es zweckmäßig sein, daß beide Lagerkörper rota­tionsunsymmetrische Form aufweisen und derart gegenüber der Wandlerplatte angeordnet sind, daß die Auflagebereiche ein­ander gegenüberliegen.It may be appropriate for the two bearing bodies to have a rotationally asymmetrical shape and to be arranged opposite the transducer plate in such a way that the bearing areas lie opposite one another.

Es kann weiterhin zweckmäßig sein, daß der Lagerkörper durch einen ersten konzentrischen Ring (ringförmiger Ansatz) gebildet ist, der in einem Sektor sich in zwei Teilringe aufspaltet.It may also be expedient for the bearing body to be formed by a first concentric ring (ring-shaped extension) which splits into two partial rings in one sector.

Die Auflagebereiche können durch spitze Lager gebildet sein. Zur Dämpfung der Teilschwingungen hat es sich her­ausgestellt, daß es zweckmäßig ist, wenn die Auflageberei­che der Lagerkörper durch plane Flächen gebildet sind.The support areas can be formed by pointed bearings. To dampen the partial vibrations, it has been found that it is expedient if the bearing areas of the bearing bodies are formed by flat surfaces.

Ebenso kann es zweckmäßig sein, wenn die planen Flächen unterschiedlich groß sind.It can also be useful if the flat areas are of different sizes.

Aus Fertigungsgründen kann es zweckmäßig sein, daß die Lagerkörper einstückig mit den Gehäuseteilen ausgebildet sind.For manufacturing reasons, it may be appropriate that the bearing body are integrally formed with the housing parts.

Im folgenden sei die Erfindung anhand von vier Figuren näher erläutert. Es zeigen

  • FIG 1 einen elektroakustischen Wandler im Schnitt
  • FIG 2 einen Träger im Schnitt
  • FIG 3 den Träger nach FIG 2 in Draufsicht
  • FIG 4 eine graphische Darstellung des Frequenzverlaufes.
The invention is explained in more detail below with reference to four figures. Show it
  • 1 shows an electroacoustic transducer in section
  • 2 shows a carrier in section
  • 3 shows the carrier according to FIG 2 in plan view
  • 4 shows a graphic representation of the frequency response.

Der in FIG 1 dargestellte Wandler weist ein Gehäuseunter­teil 1 auf, in das ein Träger 2 eingesetzt ist. Über dem Träger 2 ist ein Resonatorring 3 angeordnet. Verschlossen ist das Wandlergehäuse durch eine Abdeckung 4, die Schall­durchlaßöffnungen 5 aufweist.The converter shown in FIG. 1 has a lower housing part 1, into which a carrier 2 is inserted. A resonator ring 3 is arranged above the carrier 2. The converter housing is closed by a cover 4 which has sound passage openings 5.

Zwischen dem Träger 2 und dem Resonatorring 3 ist eine Wand­lerplatte 6 angeordnet, die mit einer piezoelektrischen Schicht 7 versehen ist. Die piezoelektrische Schicht weist hier nicht gezeigte Elektroden auf, die über Bändchen oder dergleichen an Stecker (Stecker 8 gezeigt) geführt sind. Ein Helmholtzresonator 9 verbindet den Vorraum des Trägers 2 mit dem Rückraum und dient zur Dämpfung der Grundreso­nanz.A transducer plate 6, which is provided with a piezoelectric layer 7, is arranged between the carrier 2 and the resonator ring 3. The piezoelectric layer here has electrodes, not shown, which are guided to connectors (connector 8 shown) via tapes or the like. A Helmholtz resonator 9 connects the anteroom of the support 2 with the rear area and serves to dampen the basic resonance.

Die Wandlerplatte 6 ist in ihrem Randbereich fest einge­spannt. Dazu dienen Lagerkörper, die aus zylinderförmigen ringförmigen Ansätzen 10 bis 15 des Trägers 2 sowie des Re­sonatorringes 3 bestehen.The converter plate 6 is firmly clamped in its edge area. Bearing bodies are used for this purpose, which consist of cylindrical annular projections 10 to 15 of the carrier 2 and of the resonator ring 3.

Da die Ansätze in FIG 1 nur schwer erkennbar sind, wurde der Träger in eigenen Figuren dargestellt. Der Träger nach FIG 2 und 3 wurde gegenüber der Darstellung in FIG 1 um 180o gedreht dargestellt. Deutlich erkennbar sind nun die Auflagebereiche für die Wandlerplatte, die durch ringför­mige zylinderförmige Ansätze gebildet sind. So ist zunächst der ringförmige Ansatz 16 erkennbar, der in der linken Bildebene sich in zwei Teilringe 17, 18 aufspaltet. Damit weist der Auflagebereich für die Wandlerplatte eine ro­tationsunsymmetrische Form auf.Since the approaches in FIG 1 are difficult to see, the carrier was shown in separate figures. The carrier according to FIGS. 2 and 3 was shown rotated by 180 ° in relation to the representation in FIG. The support areas for the transducer plate, which are formed by annular cylindrical projections, are now clearly recognizable. That's how it is initially the annular extension 16 can be seen, which splits into two partial rings 17, 18 in the left image plane. The support area for the converter plate thus has a rotationally asymmetrical shape.

Ähnlich ist der Auflagebereich des Resonatorringes ausge­bildet. Der Begriff des Resonatorrings wurde deshalb ge­wählt, da sich in ihm zwei λ/2 Resonatoren befinden kön­nen.The contact area of the resonator ring is designed similarly. The term resonator ring was chosen because there can be two λ / 2 resonators in it.

In FIG 4 ist nun der Frequenzgang des Wandlers dargestellt. Die Ordinate bedeutet die Empfindlichkeit E in dB, die Abs­zisse die Frequenz in Hertz. Die Linien 19, 20 grenzen den Toleranzbereich ein, zwischen dem der Frequenzverlauf sich befinden soll. Die unterbrochene Linie 21 zeigt den Fre­quenzverlauf des Wandlers bei rotationssymmetrischer Lage­rung, die geschlossene Linie 22 den Frequenzverlauf bei ei­ner Lagerung gemäß der Erfindung. Man sieht, daß die be­dämpfte Grundresonanz σ = 0 bei der Erfindung zu etwas höheren Frequenzen sich verschiebt (waagrechter Pfeil). Die Resonanz der ersten Teilschwingung σ = 1 verschiebt sich ebenfalls zu etwas höheren Werten und ist bedämpft. Die durch einen zweiten Knotenkreis gekennzeichnete Teilschwin­gung σ = 2 ist wesentlich bedämpft und liegt ebenfalls bei etwas höheren Frequenzen.4 shows the frequency response of the converter. The ordinate means the sensitivity E in dB, the abscissa the frequency in Hertz. Lines 19, 20 delimit the tolerance range between which the frequency curve is to be located. The broken line 21 shows the frequency profile of the transducer with rotationally symmetrical mounting, the closed line 22 shows the frequency profile with a mounting according to the invention. It can be seen that the damped basic resonance σ = 0 shifts to somewhat higher frequencies in the invention (horizontal arrow). The resonance of the first partial vibration σ = 1 also shifts to somewhat higher values and is damped. The partial oscillation σ = 2, characterized by a second node circle, is significantly damped and is also at somewhat higher frequencies.

Claims (6)

1. Elektroakustischer Wandler mit einer in einem Wandlerge­häuse angeordneten zwischen Lagerkörpern im Randbereich eingespannten, mit einer piezoelektrischen Schicht ver­sehenen kreisförmigen Wandlerplatte, insbesondere für Fern­sprechgeräte,
dadurch gekennzeichnet, daß zumin­dest ein Auflagebereich eines Lagerkörpers eine rotations­unsymmetrische Form aufweist.1. Electroacoustic transducer with a circular transducer plate arranged in a transducer housing and clamped between bearing bodies in the edge area and provided with a piezoelectric layer, in particular for telephone sets,
characterized in that at least one bearing area of a bearing body has a rotationally asymmetrical shape. 2. Elektroakustischer Wandler nach Anspruch 1,
dadurch gekennzeichnet, daß beide Lagerkörper rotationsunsymmetrische Form aufweisen und der­art gegenüber der Wandlerplatte angeordnet sind, daß die Auflagebereiche einander gegenüberliegen.2. Electroacoustic transducer according to claim 1,
characterized in that the two bearing bodies have a rotationally asymmetrical shape and are arranged opposite the converter plate in such a way that the bearing areas lie opposite one another. 3. Elektroakustischer Wandler nach Anspruch 1,
dadurch gekennzeichnet, daß der La­gerkörper durch einen ersten konzentrischen Ring (ringför­miger Ansatz 16) gebildet ist, der in einem Sektor sich in zwei Teilringe (17, 18) aufspaltet.3. Electroacoustic transducer according to claim 1,
characterized in that the bearing body is formed by a first concentric ring (annular extension 16) which splits into two partial rings (17, 18) in one sector. 4. Elektroakustischer Wandler nach Anspruch 1,
dadurch gekennzeichnet, daß die Auflagebereiche der Lagerkörper durch plane Flächen gebil­det sind.4. Electroacoustic transducer according to claim 1,
characterized in that the bearing areas of the bearing body are formed by flat surfaces. 5. Elektroakustischer Wandler nach Anspruch 4,
dadurch gekennzeichnet, daß die planen Flächen unterschiedlich groß sind.5. Electroacoustic transducer according to claim 4,
characterized in that the flat areas are of different sizes. 6. Elektroakustischer Wandler nach Anspruch 1,
dadurch gekennzeichnet, daß die Lagerkörper einstückig mit den Gehäuseteilen ausgebildet sind.6. electro-acoustic transducer according to claim 1,
characterized in that the bearing body is integrally formed with the housing parts.
EP89114587A 1988-08-10 1989-08-07 Electroacoustic transducer Expired - Lifetime EP0354520B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT8989114587T ATE104823T1 (en) 1988-08-10 1989-08-07 ELECTROACOUSTIC TRANSDUCER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3827165 1988-08-10
DE3827165 1988-08-10

Publications (3)

Publication Number Publication Date
EP0354520A2 true EP0354520A2 (en) 1990-02-14
EP0354520A3 EP0354520A3 (en) 1991-04-03
EP0354520B1 EP0354520B1 (en) 1994-04-20

Family

ID=6360604

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89114587A Expired - Lifetime EP0354520B1 (en) 1988-08-10 1989-08-07 Electroacoustic transducer

Country Status (6)

Country Link
US (1) US5030872A (en)
EP (1) EP0354520B1 (en)
JP (1) JPH0281600A (en)
CN (1) CN1015289B (en)
AT (1) ATE104823T1 (en)
DE (1) DE58907495D1 (en)

Cited By (1)

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Publication number Priority date Publication date Assignee Title
EP0483559A2 (en) * 1990-10-30 1992-05-06 Siemens Aktiengesellschaft Handset structure for telephone sets

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US5406161A (en) * 1994-05-24 1995-04-11 Industrial Technology Research Institute Piezoelectric composite receiver
US8594348B2 (en) * 2005-11-14 2013-11-26 Knowles Electronics Asia Pte. Ltd. Asymmetrical moving systems for a piezoelectric speaker and asymmetrical speaker

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JPS6096094A (en) * 1983-10-31 1985-05-29 Matsushita Electric Ind Co Ltd Piezo-electric type electroacoustic transducer

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0483559A2 (en) * 1990-10-30 1992-05-06 Siemens Aktiengesellschaft Handset structure for telephone sets
EP0483559A3 (en) * 1990-10-30 1993-04-14 Siemens Aktiengesellschaft Handset structure for telephone sets

Also Published As

Publication number Publication date
CN1040297A (en) 1990-03-07
US5030872A (en) 1991-07-09
ATE104823T1 (en) 1994-05-15
CN1015289B (en) 1992-01-01
JPH0281600A (en) 1990-03-22
EP0354520A3 (en) 1991-04-03
EP0354520B1 (en) 1994-04-20
DE58907495D1 (en) 1994-05-26

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