EP1202249A1 - Wasserdichte Wandler für Halbwellenwandleranordnung - Google Patents

Wasserdichte Wandler für Halbwellenwandleranordnung Download PDF

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Publication number
EP1202249A1
EP1202249A1 EP00402981A EP00402981A EP1202249A1 EP 1202249 A1 EP1202249 A1 EP 1202249A1 EP 00402981 A EP00402981 A EP 00402981A EP 00402981 A EP00402981 A EP 00402981A EP 1202249 A1 EP1202249 A1 EP 1202249A1
Authority
EP
European Patent Office
Prior art keywords
membrane
sidewalls
transducer
ultrasonic
phased array
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Withdrawn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
EP00402981A
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English (en)
French (fr)
Inventor
Philippe Loiseau
Jean Lauretti
Chakib El Hassani
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.)
IMRA Europe SAS
Original Assignee
IMRA Europe SAS
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 IMRA Europe SAS filed Critical IMRA Europe SAS
Priority to EP00402981A priority Critical patent/EP1202249A1/de
Publication of EP1202249A1 publication Critical patent/EP1202249A1/de
Withdrawn legal-status Critical Current

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    • 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
    • G10K9/125—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 with a plurality of active elements
    • 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
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/004—Mounting transducers, e.g. provided with mechanical moving or orienting device
    • 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
    • G10K13/00—Cones, diaphragms, or the like, for emitting or receiving sound in general

Definitions

  • the present invention concerns electronic scanning arrays using an ultrasonic transducer for measuring positions, by determination of distances and angles to objects in indoor and outdoor applications and may be used, for example, in parking-aid systems in vehicles.
  • the transducers are used as emitters and receivers and arranged such that at least two ultrasonic beams are generated in the observation area when they are excited by an appropriate electronic scanning signal.
  • the acoustic field of the transmitter array is given by a superposition of the vibrations from the emitters electronically excited with different phases.
  • the resulting generated wave consists of a main lobe and of secondary lobes, or side lobes.
  • the directivity of the different lobes depends on the number of transducers and the frequency (wavelength), and the radius of the transducers (angular width) and appodisation (weighting) of the excitation signals supplied to the transducers.
  • the angular distance between the lobes depends on the distance between the transducers.
  • the frequency is generally chosen to be around 40 kHz, but in any case more than 32 kHz (below this frequency ultrasounds would disturb dogs), but less than 100 kHz due to increased air attenuation of the emitted and reflected signal.
  • the application of such a transducer array in outdoor application requires a robust device with a high sensitivity.
  • the device should not only be waterproof, but it should also be capable of surviving a certain impact, such as when a vehicle hits an obstacle during a parking manoeuvre.
  • the structure used for mounting the transducer element consists of a bilaminar vibrating structure composed of a piezoelectric plate coupled to an elastic diaphragm, see e.g. the documents US-A-5 987 992, US-A4 705 981 or US-A3 736 632.
  • This structure uses the flexural vibration of a thin membrane, in general less than 1 mm, to generate or to receive acoustic waves.
  • the piezoelectric plate transforms the electrical signal into a mechanical vibration of the membrane, and during reception, the piezoelectric plate transforms the mechanical vibration into an electrical signal.
  • such a transducer has a resonant behaviour, i.e. the resonance frequency of the membrane vibration corresponds to the acoustic wave propagation frequency.
  • the membrane is attached to a rigid and large part that is called the housing.
  • FIG. 1 shows an example of a typical prior art transducer structure.
  • piezoelectric element 1 is attached to membrane 2, which is supported by housing 3.
  • the membrane has a diameter of a0, called the membrane size.
  • the transducer size is the membrane size plus the sidewall thickness and thus is d 0 .
  • the centre of the transducer is referenced as S0.
  • the membrane thickness is indicated as t 0 .
  • the housing is preferably thick.
  • this way of mounting the transducer leads to a large transducer size so that a distance of ⁇ /2 between the centres of the transducers in the arrayed sensor becomes very difficult. Indeed, if this distance is respected, the device will suffer from sensitivity and weakness problems of the active surface as will be explained in detail hereafter.
  • the relation (1) means that the transducer size is fixed by the acoustic wavelength, i.e. by the frequency f a .
  • the thickness "t" must also decrease to keep constant the frequency.
  • the membrane size "a” will be small and consequently the membrane thickness must be reduced to match the resonance frequency, thus leading to a very thin, and fragile, membrane.
  • the object of the present invention is to propose a new transducer design in which the geometry is determined in such manner to allow the realisation of a ⁇ /2 array, compatible with industrial constraint in term of reliability, performances and cost.
  • the present invention concerns an ultrasonic transducer device as defined in the appended claims.
  • the present invention also concerns an ultrasonic half-wavelength sensor array comprising at least two of such transducers, as also defined in the claims.
  • the transducer device of the present invention it is possible to provide a sensitive transducer array with ⁇ /2 arrangement between the transducer elements, the transducers being robust and suitable for outdoor applications.
  • each device 10 has a structure such that it may be used in a ⁇ /2 ultrasonic sensor phased array in indoor or outdoor application. This means that within the array, the centre of each transducer device is separated a distance ⁇ /2 from the next device's centre.
  • a sensor array may be used, for example, as a vehicle parking-aid sensor. In this case, the sensor array can be positioned, e.g. in the bumper of the vehicle so as to measure the position (distance and angle) to an obstacle.
  • a sensor may also be used, e.g., for the detection of presence and localisation of objects and/or in combination with robotics.
  • the transducer device 10 comprises a housing having thin sidewalls 13. These sidewalls are thinner than the sidewalls of the prior art device. Thus, the total diameter of the device may be reduced, and therefore also the size of the sensor array can be reduced compared to prior art arrays.
  • the housing is rectangular and has a longer side D and a shorter side d 1 .
  • the sidewalls 13 have a height referenced "h".
  • the housing further comprises a membrane 12 attached to the upper extremities of the sidewalls 13 to close of the housing at its top surface.
  • a vibrating element 11, such as a piezoelectric plate, is attached to the bottom surface of membrane 12 so as to be situated within the housing. Vibrating element 11 is arranged to cause membrane 12 to vibrate in a bending mode.
  • Membrane 12 is of rectangular or elliptical shape and has a longer side A and a shorter side a 1 . Due to the usual placing of the sensor array in a bumper of a vehicle, the longer side is referred to as the vertical size of the membrane, whereas the shorter side is referred to as the horizontal size of the membrane. Thus, the longer side A is arranged in a direction perpendicular to the scanning plane, whereas the shorter side a 1 is arranged in a direction parallel to the scanning plane.
  • the sidewalls are thinner than those of prior art devices are.
  • the present inventors have realised that by using a rectangular design and by using a specific height of the sidewalls, a greater sensitivity of the device may be obtained thereby ensuring sufficient reliability of the device allowing for outdoor applications.
  • the rectangular or elliptical design of the membrane and housing results in a larger radiating surface than is the case for prior art devices.
  • the membrane is mounted in a correct manner, and the array is placed as mentioned such that the shorter side of the membrane is in the scanning plane.
  • the membrane may then also have a thickness that is sufficient to ensure a correct and reliable operation even in outdoor applications such as vehicle parking-aid assistance, even when using a resonance frequency in the order of about 40 kHz.
  • the inventors have created a simulation model to determine the optimum configuration for the transducer according to the present invention.
  • the height "h" of the sidewalls is chosen to be 0.1 x d 1 ⁇ h ⁇ 0.6 x d 1
  • ⁇ d 1 + ⁇ ( ⁇ ⁇ d 1 /10) for a compact design.
  • the vertical size A of the membrane 12 is chosen larger than the horizontal size a1, and preferably fulfils the following relation 1.5 x a 1 ⁇ A ⁇ 3 x a 1
  • A is set to be smaller than 1.5 x a 1 , this will lead to an increase of the first vibration mode, whereas if "a" is chosen larger than 3 x a 1 , this will generate a higher vibration mode which disturbs the vertical directivity.
  • the factor ⁇ ij is dependent on the ratio A/a 1 .
  • the frequency of the vibration mode (1,1) increases when the ratio A/a 1 increases.
  • a complete FEM simulation showed that the quality factor of the mode (1,1) decreases when the ratio A/a 1 increases, while the quality factor of higher mode becomes predominant.
  • e (d 1 - a 1 )/2
  • A should be set as large as possible in accordance with the resonance frequency and the vibration mode.
  • the sensitivity of the transducer is proportional to the membrane surface.
  • the membrane horizontal size a 1 can be larger than the diameter a 0 of a conventional circular membrane as shown in Figure 1. Indeed, if the distance between the transducer centre's is maintained at ⁇ /2, then a 1 > a 0 . Furthermore, as the horizontal size A is chosen larger than a 1 , the entire membrane surface will be much larger as compared to the prior art membrane.
  • the thickness t 1 of the membrane of the transducer device according to the present invention will be greater than the thickness t 0 (see Figure 1) of the prior art transducer.
  • the transducer device according to the present invention has a higher sensitivity and is less fragile as compared to the prior art transducer.
  • the material of the housing and of membrane 12 is metallic or a polymer material.
  • aluminium or steel is suitable from a manufacturing cost point of view and advantageously also improves shielding characteristics of the device.
  • a loaded epoxy based-polymer can also be used.
  • an ultrasonic half-wavelength sensor phased array is obtained which thus is compact in size, but has a high sensitivity and is robust.
  • FIG. 3 shows a first embodiment of such a ⁇ /2 sensor phased array.
  • Array 20 comprises in this example seven transducer devices 10 according to the present invention, which are arranged so that their centres S1 are spaced apart a distance ⁇ /2.
  • Transducer devices 10 are mounted on a rigid support 21.
  • Support 21 is preferably made of resin or resin glass fibre, or resin metallic powder material to ensure sensor protection.
  • the transducer devices 10 are manufactured and mounted individually and then assembled in the support.
  • a silicone rubber 22 is used for positioning the devices in the support.
  • This seal 22 also provides an acoustic separation between the transducers. In this manner, the transducers can thus be sorted and selected before mounting to obtain optimal array performance.
  • Figure 4 shows another embodiment of a ⁇ /2 sensor array.
  • array 30 is manufactured as one part, i.e. support 31 and transducers 10 are an integral part of the array.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)
EP00402981A 2000-10-26 2000-10-26 Wasserdichte Wandler für Halbwellenwandleranordnung Withdrawn EP1202249A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP00402981A EP1202249A1 (de) 2000-10-26 2000-10-26 Wasserdichte Wandler für Halbwellenwandleranordnung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP00402981A EP1202249A1 (de) 2000-10-26 2000-10-26 Wasserdichte Wandler für Halbwellenwandleranordnung

Publications (1)

Publication Number Publication Date
EP1202249A1 true EP1202249A1 (de) 2002-05-02

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Family Applications (1)

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EP00402981A Withdrawn EP1202249A1 (de) 2000-10-26 2000-10-26 Wasserdichte Wandler für Halbwellenwandleranordnung

Country Status (1)

Country Link
EP (1) EP1202249A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005024451A2 (de) * 2003-08-11 2005-03-17 Valeo Schalter Und Sensoren Gmbh Sensor für ein nahbereichserkennungs- bzw. einparkhilfesystem eines fahrzeugs und herstellungsverfahren hierfür
WO2005064589A1 (de) * 2003-12-19 2005-07-14 Valeo Schalter Und Sensoren Gmbh Ultraschallwandlervorrichtung
DE102006008476A1 (de) * 2006-02-23 2007-09-13 Siemens Ag Verfahren und Vorrichtung zur Erzeugung eines Laufzeitsignals für eine Bestimmung eines Abstands eines Objekts durch Messung der Laufzeit von Ultraschallpulsen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1183287B (de) * 1959-04-11 1964-12-10 Aeroprojects Inc Halterung fuer das schwingende Element eines Ultraschallschwingers
US3492633A (en) * 1968-03-27 1970-01-27 Dynamics Corp America Mutual damping arrangement for hydrophones
EP0075302A1 (de) * 1981-09-23 1983-03-30 Egon Gelhard Sensor für die Durchführung einer Distanzmessung nach dem Ultraschall-Echoprinzip
WO1992002795A2 (de) * 1990-08-04 1992-02-20 Robert Bosch Gmbh Ultraschallwandler

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1183287B (de) * 1959-04-11 1964-12-10 Aeroprojects Inc Halterung fuer das schwingende Element eines Ultraschallschwingers
US3492633A (en) * 1968-03-27 1970-01-27 Dynamics Corp America Mutual damping arrangement for hydrophones
EP0075302A1 (de) * 1981-09-23 1983-03-30 Egon Gelhard Sensor für die Durchführung einer Distanzmessung nach dem Ultraschall-Echoprinzip
WO1992002795A2 (de) * 1990-08-04 1992-02-20 Robert Bosch Gmbh Ultraschallwandler

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005024451A2 (de) * 2003-08-11 2005-03-17 Valeo Schalter Und Sensoren Gmbh Sensor für ein nahbereichserkennungs- bzw. einparkhilfesystem eines fahrzeugs und herstellungsverfahren hierfür
WO2005024451A3 (de) * 2003-08-11 2006-03-02 Valeo Schalter & Sensoren Gmbh Sensor für ein nahbereichserkennungs- bzw. einparkhilfesystem eines fahrzeugs und herstellungsverfahren hierfür
US7551520B2 (en) 2003-08-11 2009-06-23 Valeo Schalter Und Sensoren Gmbh Sensor for a short-range detection system and/or parking system of a motor vehicle and method for the production thereof
CN1836270B (zh) * 2003-08-11 2010-05-12 瓦莱奥开关传感器有限公司 用于车辆的传感器及其制造方法和传感器壳体
WO2005064589A1 (de) * 2003-12-19 2005-07-14 Valeo Schalter Und Sensoren Gmbh Ultraschallwandlervorrichtung
DE102006008476A1 (de) * 2006-02-23 2007-09-13 Siemens Ag Verfahren und Vorrichtung zur Erzeugung eines Laufzeitsignals für eine Bestimmung eines Abstands eines Objekts durch Messung der Laufzeit von Ultraschallpulsen

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