EP1172019B1 - Piezoelecric vibration exciter - Google Patents

Piezoelecric vibration exciter Download PDF

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Publication number
EP1172019B1
EP1172019B1 EP00927419A EP00927419A EP1172019B1 EP 1172019 B1 EP1172019 B1 EP 1172019B1 EP 00927419 A EP00927419 A EP 00927419A EP 00927419 A EP00927419 A EP 00927419A EP 1172019 B1 EP1172019 B1 EP 1172019B1
Authority
EP
European Patent Office
Prior art keywords
piezoelectric device
piezoelectric
vibration exciter
attachment portion
loudspeaker
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.)
Expired - Lifetime
Application number
EP00927419A
Other languages
German (de)
French (fr)
Other versions
EP1172019A2 (en
Inventor
Henry Azima
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.)
NVF Tech Ltd
Original Assignee
New Transducers Ltd
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 New Transducers Ltd filed Critical New Transducers Ltd
Publication of EP1172019A2 publication Critical patent/EP1172019A2/en
Application granted granted Critical
Publication of EP1172019B1 publication Critical patent/EP1172019B1/en
Anticipated expiration legal-status Critical
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/04—Plane diaphragms
    • H04R7/045—Plane diaphragms using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/26—Damping by means acting directly on free portion of diaphragm or cone

Definitions

  • the invention relates to piezoelectric vibration exciters e.g. of the kind which may be used to apply bending wave energy to resonant panels to form loudspeakers, and to panel-form loudspeakers employing such exciters.
  • Our International patent application W097/09842 describes such resonant panel loudspeakers and vibration exciters therefor.
  • Prior art devices include 'Rainbow' piezoelectric actuators as well as more conventional piezoelectric actuators.
  • US-A-5 309 519 shows a curved piezoelectric device but with no additional mass.
  • US-A-4 654 554 a mass is attached to a free portion of a piezoelectric device but remote from the peripheral edge.
  • a vibration exciter comprising a curved piezoelectric device having an attachment portion at which the device is to be attached to a substrate to be vibrated and at least one free portion remote from the attachment portion, and a mass load provided on at least one of the or each free portion.
  • the piezoelectric device may be a ferro-electric device and may be pre-stressed. Mass loading such pre-stressed ferroelectric devices may provide a suprisingly large increase in output, of around an order of magnitude, when the devices are used to drive resonant bending wave panel.
  • the device may be arcuate in shape or may be a generally circular dished device.
  • the invention is a resonant panel-form loudspeaker driven in resonance by a vibration exciter as described above.
  • a loudspeaker 1 comprises a plate 11 capable of supporting resonant bending wave modes, as set out in W097/09842.
  • a curved, composite piezoelectric device 13 such as described in US 5632841 has an attachment portion 12 centrally located on the piezoelectric device.
  • the attachment portion 12 is mounted on a preferred, off-centre location on the panel 11.
  • the ends 14 of the device are free.
  • a mass 15 is provided along the end of the piezoelectric device to mass-load the piezoelectric vibration exciter to increase the output of the exciter.
  • Fig.2 shows a similar arrangement except that instead of a single mass 15, a pair of masses 19 are provided at each end of the piezoelectric vibration exciter 13.
  • the piezoelectric vibration exciter 21 is genuinely circular, attached to the panel at the centre of the circle, with a single mass 23 provided on the free peripheral rim 25 of the exciter.
  • the mass 23 mass-loads the piezoelectric vibration exciter to increase the output of the exciter.
  • Fig. 4 shows an alternative arrangement in which the continuous ring 23 of Fig. 3 is replaced by a plurality of discreet masses 27, symmetrically arranged the rim 25 of the piezoelectric device.
  • the invention thus provides a simple way of increasing the output of an exciter.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Description

The invention relates to piezoelectric vibration exciters e.g. of the kind which may be used to apply bending wave energy to resonant panels to form loudspeakers, and to panel-form loudspeakers employing such exciters. Our International patent application W097/09842 describes such resonant panel loudspeakers and vibration exciters therefor.
Many attempts have been made to provide piezoelectric devices having increased mechanical output displacement.
Prior art devices include 'Rainbow' piezoelectric actuators as well as more conventional piezoelectric actuators.
Conventional piezoelectric actuators exhibit limited mechanical displacement. The output of conventional piezoelectric devices is limited by the materials' basically low piezoelectric charge constant. Thus conventional devices of reasonable thickness (i.e. of the order of a few millimetres) offer only micrometer-sized mechanical output motion. 'Rainbow' actuators, 'Moonies', unimorphic and bimorphic piezoelectric actuators exhibit greater mechanical output motion. However, even the thinnest ceramic wafers, which exhibit the maximum observed output motion, provide a displacement limited to approximately lmm of motion in the z-axis direction for a device that is 3-4cm long. Additionally, 0.25mm thick ceramic devices are extremely brittle and fragile so that they are prone to breakage and require special handling.
U.S. patents 5,632,841 and 5,802,195 and International application W096/31333 describe high displacement ferro-electric devices. US-A-5 309 519 shows a curved piezoelectric device but with no additional mass. In US-A-4 654 554 a mass is attached to a free portion of a piezoelectric device but remote from the peripheral edge.
It is an object of the invention to provide a piezoelectric device of enhanced output.
According to the invention there is provided a vibration exciter comprising a curved piezoelectric device having an attachment portion at which the device is to be attached to a substrate to be vibrated and at least one free portion remote from the attachment portion, and
   a mass load provided on at least one of the or each free portion.
The piezoelectric device may be a ferro-electric device and may be pre-stressed. Mass loading such pre-stressed ferroelectric devices may provide a suprisingly large increase in output, of around an order of magnitude, when the devices are used to drive resonant bending wave panel.
The device may be arcuate in shape or may be a generally circular dished device.
From another aspect the invention is a resonant panel-form loudspeaker driven in resonance by a vibration exciter as described above.
Specific embodiments of the invention will now be described, purely by way of example, with reference to the accompanying drawings in which
  • Figure 1 shows a first embodiment of a piezoelectric device according to the invention,
  • Figure 2 shows a second embodiment,
  • Figure 3 shows a third embodiment and
  • Figure 4 shows a fourth embodiment.
    • Referring to Figure 1, a loudspeaker 1 comprises a plate 11 capable of supporting resonant bending wave modes, as set out in W097/09842. A curved, composite piezoelectric device 13 such as described in US 5632841 has an attachment portion 12 centrally located on the piezoelectric device. The attachment portion 12 is mounted on a preferred, off-centre location on the panel 11. The ends 14 of the device are free. At each end of the piezoelectric device 13 a mass 15 is provided along the end of the piezoelectric device to mass-load the piezoelectric vibration exciter to increase the output of the exciter.
    Fig.2 shows a similar arrangement except that instead of a single mass 15, a pair of masses 19 are provided at each end of the piezoelectric vibration exciter 13.
    In Fig. 3, the piezoelectric vibration exciter 21 is genuinely circular, attached to the panel at the centre of the circle, with a single mass 23 provided on the free peripheral rim 25 of the exciter. The mass 23 mass-loads the piezoelectric vibration exciter to increase the output of the exciter.
    Fig. 4 shows an alternative arrangement in which the continuous ring 23 of Fig. 3 is replaced by a plurality of discreet masses 27, symmetrically arranged the rim 25 of the piezoelectric device.
    The invention thus provides a simple way of increasing the output of an exciter.

    Claims (11)

    1. A vibration exciter comprising
         a curved piezoelectric device (13) having an attachment portion (12) at which the device is to be attached to a substrate to be vibrated (11) and at least one free end or peripheral rim portion (14) remote from the attachment portion (12), and
         a mass load provided on at least one of the or each free end or peripheral rim portion.
    2. A vibration exciter according to claim 1 wherein the piezoelectric device (13) is a ferroelectric device.
    3. A vibrations exciter according to claim 2 wherein the ferroelectric piezoelectric device is a pre-stressed device.
    4. A vibration exciter according to any preceding claim wherein the piezoelectric device is arcuate.
    5. A vibration exciter according to any of claims 1 to 3 wherein the piezoelectric device is dish-shaped.
    6. A loudspeaker comprising
         a diaphragm (11) capable of vibration to produce sound,
         a curved piezoelectric device (13) having an attachment portion (12) mounted to the diaphragm and at least one free end or peripheral rim portion (14) remote from the attachment portion (12), and
         a mass load provided on at least one of the or each free end or peripheral rim portion (14).
    7. A loudspeaker according to claim 6 wherein the diaphragm (11) is a panel capable of supporting bending waves and the piezoelectric device (13) is arranged to excite bending waves in the panel.
    8. A loudspeaker according to claim 6 or .7 wherein the piezoelectric device (13) is a ferroelectric device.
    9. A loudspeaker according to claim 8 wherein the ferroelectric device (13) is a pre-stressed device.
    10. A loudspeaker according to any of claims 6 to 9 wherein the piezoelectric device (13) is arcuate.
    11. A loudspeaker according to any of claims 6 to 9 wherein the piezoelectric device (13) is dish-shaped.
    EP00927419A 1999-04-29 2000-04-28 Piezoelecric vibration exciter Expired - Lifetime EP1172019B1 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    GBGB9910216.2A GB9910216D0 (en) 1999-04-29 1999-04-29 Vibration exciter
    GB9910216 1999-04-29
    PCT/GB2000/001485 WO2000067525A2 (en) 1999-04-29 2000-04-28 Piezoelectric vibration exciter

    Publications (2)

    Publication Number Publication Date
    EP1172019A2 EP1172019A2 (en) 2002-01-16
    EP1172019B1 true EP1172019B1 (en) 2003-09-17

    Family

    ID=10852721

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP00927419A Expired - Lifetime EP1172019B1 (en) 1999-04-29 2000-04-28 Piezoelecric vibration exciter

    Country Status (8)

    Country Link
    EP (1) EP1172019B1 (en)
    JP (1) JP2002543727A (en)
    CN (1) CN1343438A (en)
    AU (1) AU4582400A (en)
    DE (1) DE60005329D1 (en)
    GB (1) GB9910216D0 (en)
    TW (1) TW472497B (en)
    WO (1) WO2000067525A2 (en)

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE102021213003A1 (en) 2021-11-18 2023-05-25 Continental Automotive Technologies GmbH Transducer for generating sound waves and display

    Families Citing this family (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    WO2009001769A1 (en) * 2007-06-27 2008-12-31 Alps Electric Co., Ltd. Electrostriction actuator module

    Family Cites Families (5)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    JPS5819099A (en) * 1981-07-27 1983-02-03 Murata Mfg Co Ltd Piezoelectric type loud speaker
    GB2166022A (en) * 1984-09-05 1986-04-23 Sawafuji Dynameca Co Ltd Piezoelectric vibrator
    US5115472A (en) * 1988-10-07 1992-05-19 Park Kyung T Electroacoustic novelties
    UA51671C2 (en) * 1995-09-02 2002-12-16 Нью Транзд'Юсез Лімітед Acoustic device
    BE1011085A4 (en) * 1997-04-03 1999-04-06 Sonitron Naamloze Vennootschap ELEMENT FOR PLAYING AND / OR RECORDING SOUND.

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE102021213003A1 (en) 2021-11-18 2023-05-25 Continental Automotive Technologies GmbH Transducer for generating sound waves and display

    Also Published As

    Publication number Publication date
    DE60005329D1 (en) 2003-10-23
    WO2000067525A3 (en) 2001-03-08
    JP2002543727A (en) 2002-12-17
    AU4582400A (en) 2000-11-17
    EP1172019A2 (en) 2002-01-16
    GB9910216D0 (en) 1999-06-30
    CN1343438A (en) 2002-04-03
    WO2000067525A2 (en) 2000-11-09
    TW472497B (en) 2002-01-11

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