EP0007036A1 - Electroacoustic transducer - Google Patents

Electroacoustic transducer Download PDF

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Publication number
EP0007036A1
EP0007036A1 EP79102142A EP79102142A EP0007036A1 EP 0007036 A1 EP0007036 A1 EP 0007036A1 EP 79102142 A EP79102142 A EP 79102142A EP 79102142 A EP79102142 A EP 79102142A EP 0007036 A1 EP0007036 A1 EP 0007036A1
Authority
EP
European Patent Office
Prior art keywords
transducer
plate
converter
oscillation
sensitivity
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Withdrawn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
EP79102142A
Other languages
German (de)
French (fr)
Inventor
Konrad Dr. Walliser
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP0007036A1 publication Critical patent/EP0007036A1/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/222—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only  for microphones
    • 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 transducer plate, which is clamped at its edge area with the aid of bearing bodies and is provided with a piezoelectric layer.
  • transducers In the frequency response of transducers, in particular transducers with a piezoelectric layer provided transducer plate, undesirable increases in sensitivity mostly occur due to harmonics of the transducer membrane used. This applies in particular to the fourth-order partial oscillation, which is characterized by a circle of nodes within the oscillating surface.
  • the transducer element is tuned so that the basic resonance is within the transmission range of 200-4000 Hz.
  • the greatest increase in sensitivity in the basic resonance can then be easiest reduced by a damped absorption resonator coupled to the transducer element.
  • higher-order partial vibrations also fall within the transmission range.
  • the second and third partial oscillations which would normally lead to drops in the frequency response, are largely avoided by the converter being constructed as symmetrically as possible.
  • the fourth partial oscillation an undesirable increase occurs in the frequency response, whereby the danger of whistling when installing such transducers in a handset of a telephone is undesirably increased.
  • the converter plate is reinforced from 230 ⁇ m to 290 ⁇ m.
  • the resonance frequency of the fourth partial vibration is shifted from 4.1 kHz to 5.2 kHz.
  • the frequency of the basic resonance is thus somewhat higher, namely at 1400 Hz instead of 1200 Hz. This shift in the increase can be easily corrected by a slight change in the coupling in the sound field.
  • the converter plate is covered with a plastic layer. This dampens the fourth partial vibration in particular.
  • a layer of 50 .mu.m causes the increase in the fourth partial oscillation to be reduced by approximately 3 dB.

Abstract

The invention relates to an electro- acoustic transducer with a transducer plate which is clamped in the region of its edge by means of supports, is subjected to bending stress, and is provided with a piezo-electric layer and which, in the frequency response intended for transmission, (200 to 3,500 Hz approx.), in addition to the resonance peak resulting from the first harmonic of the transducer plate, also executes harmonics of a higher order. The aim of the invention is to contrive the fourth harmonic to be such that it does not have a disturbing effect. The aim is realised in that the fourth harmonic characterised by a circular node is displaced into a higher frequency range outside of the frequency range of interest in respect of telephone traffic to such an extent that a disturbing increase in sensitivity no longer occurs. Can be used in piezo-microphones.

Description

Die Erfindung betrifft einen elektroakustischen Wandler mit einer an ihrem Randbereich mit Hilfe von Lagerkörpern eingespannten auf Biegung beanspruchten mit einer piezoelektrischen Schicht versehenen Wandlerplatte, die in dem zur Übertragung bestimmten Frequenzgang neben der Grundschwingung der Wandlerplatte entstehende Resonanzspitze auch Teilschwingungen höherer Ordnung ausbildet.The invention relates to an electroacoustic transducer with a transducer plate, which is clamped at its edge area with the aid of bearing bodies and is provided with a piezoelectric layer.

Im Frequenzgang von Wandlern, insbesondere von Wandlern mit einer piezoelektrischen Schicht versehenen Wandlerplatte treten meistens durch Oberschwingungen der verwendeten Wandlermembran unerwünschte Empfindlichkeits- überhöhungen auf. Dies betrifft besonders die Teilschwingung vierter Ordnung, die durch einen Knotenkreis innerhalb der schwingenden Fläche gekennzeichnet ist.In the frequency response of transducers, in particular transducers with a piezoelectric layer provided transducer plate, undesirable increases in sensitivity mostly occur due to harmonics of the transducer membrane used. This applies in particular to the fourth-order partial oscillation, which is characterized by a circle of nodes within the oscillating surface.

Zur Steigerung der Empfindlichkeit von Wandlern stimmt man das Wandlerelement so ab, daß die Grundresonanz innerhalb des Übertragungsbereiches von 200- 4000 Hz liegt. Die große Empfindlichkeitsüberhöhung bei der Grundresonanz kann man dann am einfachsten durch einen an das Wandlerelement angekoppelten, gedämpften Absorptionsresonator abbauen. Damit fallen jedoch auch Teilschwingungen höherer Ordnung in den Übertragungsbereich. Die zweite und dritte Teilschwingung, die normalerweise zu Einbrüchen im Frequenzgang führen würde, wird durch einen möglichst symmetrischen Aufbau des Wändlers weitestgehend vermieden. Bei der vierten Teilschwingung tritt im Frequenzgang eine unerwünschte Überhöhung auf, wodurch die Pfeifpunktgefahr beim Einbau solcher Wandler in einen Handapparat eines Fernsprechers unerwünscht erhöht wird.To increase the sensitivity of transducers, the transducer element is tuned so that the basic resonance is within the transmission range of 200-4000 Hz. The greatest increase in sensitivity in the basic resonance can then be easiest reduced by a damped absorption resonator coupled to the transducer element. However, higher-order partial vibrations also fall within the transmission range. The second and third partial oscillations, which would normally lead to drops in the frequency response, are largely avoided by the converter being constructed as symmetrically as possible. With the fourth partial oscillation, an undesirable increase occurs in the frequency response, whereby the danger of whistling when installing such transducers in a handset of a telephone is undesirably increased.

Nun ist es bekannt, daß sich wegen der Resonanz von Einsprache des Handapparates und der Fassung des Wandlers an der oberen Frequenzbandgrenze ein steiler Empfindlichkeitsabfall einstellt.It is now known that a steep drop in sensitivity occurs due to the resonance of the speech of the handset and the version of the converter at the upper frequency band limit.

Es ist Aufgabe der vorliegenden Erfindung, die vierte Teilschwingung so festzulegen, daß diese nicht störend wirkt und ein Verlust der Empfindlichkeit des Wandlers weitestgehend vermieden wird.It is an object of the present invention to determine the fourth partial vibration in such a way that it does not have a disturbing effect and a loss of sensitivity of the transducer is largely avoided.

Diese Aufgabe wird gemäß der Erfindung dadurch gelöst, daß die durch einen Knotenkreis gekennzeichnete vierte Teilschwingung soweit in einen höheren Frequenzbereich außerhalb des für den Fernsprechverkehr interessanten Frequenzbereichs (200 Hz bis ca. 3500 Hz) verlegt ist, daß die durch diese Teilschwingung hervorgerufene Empfindlichkeitsüberhöhung keinen störenden Einfluß auf den Frequenzgang des Wandlers ausübt, wobei einzelne oder mehrere der folgenden Maßnahmen wählbar sind :

  • a) Verstärkung der Wandlerplattendicke
  • b) Überzug der Wandlerplatte mit einer dämpfenden Kunststoffschicht
  • c) Wahl einer weicheren Lagerung im Randbereich der Wandlerplatte
  • d) Wahl der Form der Wandlerplatte
  • e) Wahl der Größe der piezokeramischen Schicht
This object is achieved according to the invention in that the fourth partial oscillation, characterized by a node circle, is so far moved into a higher frequency range outside the frequency range of interest for telephone traffic (200 Hz to approx. 3500 Hz) that the increase in sensitivity caused by this partial oscillation does not cause any disturbance Influences the frequency response of the transducer, whereby one or more of the following measures can be selected:
  • a) Reinforcing the transducer plate thickness
  • b) covering the converter plate with a damping plastic layer
  • c) Choosing a softer bearing in the edge area of the converter plate
  • d) Choice of the shape of the converter plate
  • e) Choice of the size of the piezoceramic layer

Durch das Verlegen der vierten Teilschwingung in einen höheren Frequenzbereich gelangt diese in einen Bereich, wo sich normalerweise der den erwähnte steile Empfindlichkeitsäbfall einstellt. In diesem Bereich wirkt die Empfindlichkeitsüberhöhung nicht mehr störend. Die Empfindlichkeit des Wandlers wird dabei kaum abgesenkt.By relocating the fourth partial oscillation to a higher frequency range, it reaches a range where the steep sensitivity drop mentioned occurs normally. In this area, the sensitivity increase no longer has a disruptive effect. The sensitivity of the converter is hardly reduced.

Weitere vorteilhafte Einzelheiten der Erfindung sind den Unteransprüchen sowie den nachfolgenden Beispielen entnehmbar.Further advantageous details of the invention can be found in the subclaims and the examples below.

Beispiel 1example 1

Bei vorgegebener Lagerung der Wandlerplatte wird die Wandlerplatte von 230 µm auf 290 µm verstärkt. Die Resonanzfrequenz der vierten Teilachwingung wird von 4,1 kHz auf 5,2 kHz verschoben. Damit liegt die Frequenz der Grundresonanz auch etwas höher, und zwar bei 1400 Hz statt bei 1200 Hz. Diese Verachiebung der Erhöhung kann durch eine geringe Änderung der Ankopplung im Schallfeld leicht korrigiert werden.For a given storage of the converter plate, the converter plate is reinforced from 230 µm to 290 µm. The resonance frequency of the fourth partial vibration is shifted from 4.1 kHz to 5.2 kHz. The frequency of the basic resonance is thus somewhat higher, namely at 1400 Hz instead of 1200 Hz. This shift in the increase can be easily corrected by a slight change in the coupling in the sound field.

Beispiel 2Example 2

Die Wandlerplatte wird mit einer Kunststoffschicht überzogen. Dadurch wird besonders die vierte Teilschwingung gedämpft. Eine Schicht von 50 um bewirkt eine Absenkung der Überhöhung bei der vierten Teilschwingung um etwa 3 dB.The converter plate is covered with a plastic layer. This dampens the fourth partial vibration in particular. A layer of 50 .mu.m causes the increase in the fourth partial oscillation to be reduced by approximately 3 dB.

Claims (7)

1. Elektroakustischer Wandler mit einer an ihrem Randbereich mit Hilfe von Lagerkörpern eingespannten auf Biegung beanspruchten mit einer piezoelektrischen Schicht versehenen Wandlerplatte, die in dem zur Übertragung bestimmten Frequenzgang neben der Grundschwingung der Wandlerplatte entstehende Resonanzspitze auch Teilschwingungen höherer Ordnung ausbildet, dadurch gekennzeichnet, daß die durch einen Knotenkreis gekennzeichnete vierte Teilschwingung soweit in einen höheren Frequenzbereich außerhalb des für den Fernsprechverkehr interessanten Frequenzbereichs (200 Hz bis ca. 3500 Hz) verlegt ist, daß die durch diese Teilschwingung hervorgerufene Empfindlichkeitsüberhöhung keinen störenden Einfluß auf den Frequenzgang des Wandlers ausübt, wobei einzelne oder mehrere der folgenden Maßnahmen wählbar sind: a) Verstärkung der Wandlerplattendicke b) Überzug der Wandlerplatte mit einer dämpfenden Kunststoffschicht c) Wahl einer weicheren Lagerung im Randbereich der Wandlerplatte d) Wahl der Form der Wandlerplatte e) Wahl der Größe der piezokeramischen Schicht 1. Electroacoustic transducer with a clamped at its edge area with the aid of bearing bodies on bending with a piezoelectric layer provided transducer plate, which in the frequency response intended for transmission in addition to the fundamental vibration of the transducer plate also forms higher-order partial vibrations, characterized in that the a fourth sub-oscillation characterized by a node circle is so far moved to a higher frequency range outside the frequency range of interest for telephone traffic (200 Hz to approx. 3500 Hz) that the increase in sensitivity caused by this sub-oscillation has no disruptive influence on the frequency response of the transducer, with one or more the following measures can be selected: a) Reinforcing the transducer plate thickness b) covering the converter plate with a damping plastic layer c) Choosing a softer bearing in the edge area of the converter plate d) Choice of the shape of the converter plate e) Choice of the size of the piezoceramic layer 2. Wandler nach Anspruch 1, dadurch gekennzeichnet , daß die Wandlerplatte um etwa 60 um auf 290 µm verstärkt ausgebildet ist, wodurch die vierte Teilschwingung von 4,1 kHz auf etwa 5,2 kHz verschoben wird.2. Transducer according to claim 1, characterized in that the transducer plate is reinforced by about 60 to 290 microns, whereby the fourth part of 4.1 kHz is shifted to about 5.2 kHz. 3. Wandler nach Anspruch 1, dadurch gekennzeichnet , daß die Wandlerplatte in ihrem Randbereich durch beidseitig am Plattenrand angreifende Lagerkörper hoher Elastizität gelagert ist.3. Transducer according to claim 1, characterized in that the converter plate is mounted in its edge region by bearing bodies of high elasticity acting on both sides of the plate edge. 4. Wandler nach Anspruch 1, dadurch gekennzeichnet , daß die Wandlerplatte pentagonale, hexogonale oder oktogonale Form aufweist.4. A converter according to claim 1, characterized in that the converter plate has a pentagonal, hexagonal or octagonal shape. 5. Wandler nach Anspruch 1, dadurch gekennzeichnet , daß die Kunststoffschicht zu beiden Seiten der Wandlerplatte aufgebracht ist.5. Converter according to claim 1, characterized in that the plastic layer is applied to both sides of the converter plate. 6. Wandler nach Anspruch 1, dadurch gekennzeichnet , daß die Kunststoffschicht auf einer Seite der Wandlerplatte aufgebracht ist.6. Converter according to claim 1, characterized in that the plastic layer is applied to one side of the converter plate. 7. Wandler nach Anspruch 1, dadurch gekennzeichnet , daß die vierte Teilschwinging in den durch den durch Fassung und Einsprache des Handapparatekörpers hervorgerufenen Empfindlichkeitsabfall des Wandlers verschoben ist.7. Transducer according to claim 1, characterized in that the fourth part of the oscillation is shifted into the drop in sensitivity of the transducer caused by the version and objection of the handset body.
EP79102142A 1978-07-17 1979-06-27 Electroacoustic transducer Withdrawn EP0007036A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2831362 1978-07-17
DE19782831362 DE2831362A1 (en) 1978-07-17 1978-07-17 ELECTROACOUSTIC CONVERTER

Publications (1)

Publication Number Publication Date
EP0007036A1 true EP0007036A1 (en) 1980-01-23

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ID=6044593

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79102142A Withdrawn EP0007036A1 (en) 1978-07-17 1979-06-27 Electroacoustic transducer

Country Status (8)

Country Link
EP (1) EP0007036A1 (en)
JP (1) JPS5516594A (en)
AR (1) AR228018A1 (en)
AU (1) AU4893079A (en)
BR (1) BR7904528A (en)
DE (1) DE2831362A1 (en)
GB (1) GB2025732A (en)
ZA (1) ZA793578B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0034730A1 (en) * 1980-02-15 1981-09-02 Siemens Aktiengesellschaft Transducer disk for piezo-electric transducers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS582322A (en) * 1981-06-30 1983-01-07 Nitto Electric Ind Co Ltd Epoxy resin composition for encapsulation of semiconductor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1299724B (en) * 1966-10-21 1969-07-24 Siemens Ag Microphone capsule with a piezoelectric transducer element and a transistor amplifier
DE1948932A1 (en) * 1968-09-30 1970-04-09 Philips Nv Converter for converting acoustic vibrations into electrical vibrations and vice versa in the form of a vibrating plate with at least one layer of piezoelectric material
US3746898A (en) * 1971-10-18 1973-07-17 Bell Telephone Labor Inc Electroacoustic transducer having improved transducing element supporting means
DE2318027A1 (en) * 1972-04-10 1973-11-08 Motorola Inc ACOUSTIC CONVERTER WITH A PIEZOELECTRIC DRIVER
US3846650A (en) * 1970-10-08 1974-11-05 Dynamics Corp Massa Div Electroacoustic transducer of the vibratile diaphragm type with controlled uniformity of performance characteristics and method for controlling uniformity

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1299724B (en) * 1966-10-21 1969-07-24 Siemens Ag Microphone capsule with a piezoelectric transducer element and a transistor amplifier
DE1948932A1 (en) * 1968-09-30 1970-04-09 Philips Nv Converter for converting acoustic vibrations into electrical vibrations and vice versa in the form of a vibrating plate with at least one layer of piezoelectric material
US3846650A (en) * 1970-10-08 1974-11-05 Dynamics Corp Massa Div Electroacoustic transducer of the vibratile diaphragm type with controlled uniformity of performance characteristics and method for controlling uniformity
US3746898A (en) * 1971-10-18 1973-07-17 Bell Telephone Labor Inc Electroacoustic transducer having improved transducing element supporting means
DE2318027A1 (en) * 1972-04-10 1973-11-08 Motorola Inc ACOUSTIC CONVERTER WITH A PIEZOELECTRIC DRIVER

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF THE AUDIO ENGINEERING SOCIETY, Vol. 17, April 1969, Nr. 2, Seiten 174,175 New York, U.S.A. J. ROOS UND J. KOORNEEF: "Thin Bilaminar Piezodisks Uses as Microphone and Telephone Membranes" * Seite 174, linke Spalte, Zeile 1 - Seite 175, linke Spalte, Zeile 23; figuren 1,2 * *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0034730A1 (en) * 1980-02-15 1981-09-02 Siemens Aktiengesellschaft Transducer disk for piezo-electric transducers
EP0034730B1 (en) * 1980-02-15 1984-12-05 Siemens Aktiengesellschaft Transducer disk for piezo-electric transducers

Also Published As

Publication number Publication date
AU4893079A (en) 1980-01-24
AR228018A1 (en) 1983-01-14
GB2025732A (en) 1980-01-23
BR7904528A (en) 1980-04-08
ZA793578B (en) 1980-06-25
DE2831362A1 (en) 1980-01-31
JPS5516594A (en) 1980-02-05

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Inventor name: WALLISER, KONRAD, DR.