Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
  • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
  • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
  • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
  • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
  • B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
  • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
  • B06B3/00—Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
• • 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
• • 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 
  • H04R1/26—Spatial arrangements of separate transducers responsive to two or more frequency ranges
• • 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

Definitions

• the present invention is based on an electroacoustic transducer according to the preamble of claim 1.
• US 2010/0020646 A1 describes an ultrasonic transducer, which provides a transmission path between a vibrating surface (piezoelectric ceramic) of the transducer material and a medium in which the vibrations are transmitted, wherein a so-called ⁇ / 2 resonator (thickness oscillator) with a essentially rod-shaped
• Transmission element which is variable in shape, length and cross-section, is mentioned. In particular, however, corresponds to the preferred length of the transmission element ⁇ / 4.
• the design of the transmission element depends on the acoustic emission characteristic to be achieved at the resonant frequency.
• the transmission element is integrated in a protective housing of the sound transducer.
• US 8,320,218 B2 describes, starting from the described in US 2010/0020646 AI piezoelectric ultrasonic transducer with a front and rear transmission element, an ultrasonic transducer in concealed
• the front, rod-shaped transmission element is formed as a composite element, further comprising a smooth plate, for example, a part of the material surface (bumper, vehicle door) on which the
• Ultrasonic transducer is installed hidden. This smooth area is part of the resonator structure and is excited by the electroacoustic transducer. Furthermore, means are described to install the ultrasonic transducer hidden and protected.
• Ultrasonic transducer caused local thickness vibrations of the component. Accordingly, an improved radiation characteristic of the ultrasonic lobe can be achieved and a concealed installation can be realized.
• DE 10 2009 040 264 A1 relates to an elongated ultrasonic transducer with a length dimension which is larger than the width dimension and which can be constructed from a plurality of disks, designed as a monolithic piezoceramic or as a rod-shaped piezoelectric element.
• the invention proposes a novel structure for an electroacoustic transducer, which is particularly suitable for concealed installation, for example in cladding elements of vehicles.
• the invention is based on the idea of creating an electroacoustic transducer which combines the features and advantages of the known concepts of the thickness vibrator and the bending transducer. For example, the electrical contacting of the piezoelectric element in a bending transducer is easily accessible from the outside.
• piezoceramic material need not be biased to pressure compared to a standard ( ⁇ / 2 thickness oscillator). This is advantageous because piezoceramics are usually able to withstand tensile stresses only to a small extent without being damaged. Furthermore, one is
• Resonance frequency (working frequency) geometry and material parameters of both the thickness and the bending oscillator are available.
• the parameters can be selected depending on the desired application, for example robust design compared to tolerances.
• an electroacoustic transducer which comprises a housing and a vibrating structure.
• the vibrating structure is formed by at least one piezoelectric element, a diaphragm and an acoustic transducer.
• a membrane is understood in particular to mean a plate which, although having a small thickness in comparison to its surface, can therefore execute bending oscillations in a direction perpendicular to its surface, but has a certain flexural rigidity.
• the membrane according to the invention is connected to the piezoelectric element, so that according to the known principle of an electroacoustic transducer mechanical vibrations of the membrane on the
• piezoelectric element can be transmitted and generate corresponding electrical signals.
• corresponding electrical signals By applying corresponding electrical signals to the piezoelectric element mechanical vibrations are generated, which are transmitted to the membrane.
• the acoustic transducer transmits vibrations to or from the diaphragm.
• the acoustic transmitter has a first surface and a second surface parallel to the first surface, wherein the first surface of the acoustic transducer is coupled to the membrane and the second surface of the acoustic transducer is adapted to radiate and / or receive sound waves.
• a coupling is understood as meaning a mechanical connection which allows the transmission of sound waves.
• the membrane is designed as a bending oscillator and the acoustic transformer is designed as a thickness oscillator.
• the acoustic transformer is designed in particular as a so-called ⁇ / 2-thickness oscillator, wherein ⁇ corresponds to the wavelength of a thickness vibration of the vibrating structure and the speed of sound of the Material and the frequency of the vibration is dependent.
• the transmitter is in resonance when the wavelength produced by the excitation is a multiple of ⁇ / 2.
• Thick vibrations in other words excited periodic length changes in the longitudinal direction. Since the acoustic transducer is connected to the membrane, these thickness vibrations in turn cause
• Thick vibrations of the acoustic transducer and sound waves are radiated from the second surface of the acoustic transmitter.
• the electroacoustic transducer according to the invention can thus be used as a sensor in an environment detection system as shown in FIG.
• Surrounding ultrasonic signals can be emitted, which are reflected on objects in the environment.
• the reflected echo signals can be received by the sensor and further processed by a corresponding electronics in a known manner. For example, obstacles can be detected and collisions avoided.
• the first surface of the acoustic transducer is coupled to a first surface of the membrane.
• a second surface of the membrane is connected to the piezoelectric element, for example by gluing the piezoelectric element.
• a construction can be implemented by connecting the membrane on a first surface to the first surface of the acoustic transmitter in such a way that transmission of the acoustic signal is as low as possible Vibrations is guaranteed. This can be achieved for example by gluing with a suitable adhesive or welding or screwing.
• the membrane may also be integral with the acoustic
• the piezoelectric element is preferably glued over the entire surface of the membrane.
• the shape of the piezoelectric element may be circular, elliptical, angular or arbitrary. Further, an embodiment with an annular configuration of the piezoelectric element is possible.
• the acoustic transformer comprises an im
• rod-shaped element Essentially rod-shaped element and a plate. Under rod-shaped should be understood that the element is solid and a
• the end faces can be arbitrarily shaped, for example circular, oval, or rectangular. It is also conceivable to design the end faces differently sized and / or differently shaped.
• An end face of the rod-shaped element is connected to the membrane. The other end face is connected to the plate, wherein the
• Membrane and / or the plate can also be integrally formed with the rod-shaped element.
• the surface of the plate facing away from the rod-shaped element thus forms the second surface of the acoustic transmitter, which is suitable for emitting and / or receiving sound waves.
• the emission characteristic of the electroacoustic transducer is determined.
• Angular dependence of the signal strength as well as to the resonance frequencies are set. Usual frequencies are in the range of 30 to 150 kHz.
• the plate may be formed, for example, as part of a cladding element of a vehicle, in particular a bumper.
• the plate can be formed integrally with the cladding element or as a separate part be. It is advantageous for the acoustic emission characteristics if the plate has a smaller thickness than the surrounding cladding element. Therefore, a cladding element, for example, in the area through which the plate is formed may have a reduced material thickness.
• thicknesses of 0.1 to 10 mm or more generally a ratio between a diameter of the plate and the thickness of the plate of about 10/1.
• the housing of the electroacoustic transducer according to the invention is connected to an inner surface of the cladding element such that the electroacoustic transducer is not visible from the outside. This results in the advantage that the converter can be arranged protected from environmental influences, such as dirt or moisture. In addition, there are creative advantages.
• the housing can also be integrally formed with the cladding element.
• the membrane may preferably be fastened to the housing by means of a bearing structure.
• the housing can, for example, have a circumferential region with a reduced wall thickness, to which the membrane is fastened in its edge region, for example by gluing or by clamping.
• the storage can also be designed to be movable, for example, in that the contact area between the membrane and the housing is small in comparison to the total area of the membrane and thus flexible.
• the rod-shaped element by means of a
• the bearing structure to be held on the housing.
• the bearing structure is preferably arranged in particular at a height of the rod-shaped element, which corresponds to a vibration node of a resonant oscillation of the oscillating structure.
• the bearing structure is located at a position at which the rod-shaped element undergoes little or no change in length with an excited thickness vibration.
• the bearing structure is only slightly mechanically loaded.
• the rod-shaped element has a decreasing in the direction of the membrane connected to the first surface and / or in the direction of the end face connected to the plate
• the rod-shaped element thus runs in the direction of the membrane and / or in the direction of the plate pointed. Due to the resulting reduced connection surface between the rod-shaped element and the membrane or the plate is effected that the rocking properties, in particular the bend, the membrane and / or the plate are only slightly hindered. This results in an improved sensitivity for incident sound waves and a higher signal strength of the emitted acoustic
• the rod-shaped element has at least one mounting aid element on its end face facing the plate. This can be designed as a depression or increase. It can too
• the plate has at its end face of the rod-shaped element zugegewanden
• FIG. 1 shows an electroacoustic transducer according to a first embodiment of the invention.
• Figure 2 shows an electroacoustic transducer according to a second embodiment of the invention.
• FIG. 3 shows an electroacoustic transducer according to a third embodiment of the invention.
• Figure 4 shows the electroacoustic transducer according to the first embodiment of the invention together with a diagram of the deflection in the thickness direction of the acoustic transducer.
• FIG. 1 shows a schematic longitudinal section through an electroacoustic transducer 1 according to a first embodiment of the invention.
• the electroacoustic transducer 1 comprises a housing 180 and a vibrating structure 110.
• the vibrating structure 110 comprises a piezoelectric element 150, which in this example is designed as a piezoceramic disk.
• the piezoceramic disk is bonded to the underside 122 of the membrane 120.
• the piezoceramic disk has substantially the same
• electrical connection means 190 are provided, which are contacted with electrodes of the piezoelectric element 150 and are shown here only schematically.
• a rod-shaped element 145 is attached on the top 121 of the membrane.
• a first surface 141 of the rod-shaped element is connected to the membrane.
• the attachment can for example by screws and / or Welding and / or gluing done.
• the rod-shaped element 145 is attached with its second surface (end face) 146 to a plate 240, in particular glued.
• the plate 240 is integrally connected to a trim element 200, which in this example is the bumper or trim strip of a motor vehicle.
• the housing 180 is on the inside of the trim element 200
• the housing 180 is in this example in
• the membrane 120 is mounted in an edge region 185 of the housing 180.
• the housing 180 has a smaller wall thickness in this edge region 185.
• the bearing 170 may be fixed, for example by clamping or gluing. Alternatively, the bearing 170 may have some mobility, this being achieved by making the contact area between the diaphragm 120 and the housing 180 small and thus compliant.
• the outwardly facing surface 142 of the plate 240 is suitable
• the plate 240 and the rod-shaped element 145 form the acoustic transducer 140 according to the invention, which is provided by flexural vibrations of the diaphragm 120
• Thick vibrations can be excited. In case of reception, this principle is exactly the opposite. Sound waves strike the surface 142 and excite the plate 240. This stimulates the rod-shaped element 145, which in turn excites the membrane 120 to perform bending vibrations. Since the piezoelectric element 150 is bonded to the diaphragm 120, voltage signals are generated on the piezoelectric element 150, which can be tapped by the electrical connection means 190 and the
• the vibrating structure 110 will vibrate at a certain resonant frequency.
• the longitudinal extent d of the oscillating structure 110 corresponds to half the wavelength ( ⁇ / 2) of the resonance oscillation.
• the longitudinal extension d is essentially determined by the length of the rod-shaped element 145, this is therefore also referred to as ⁇ / 2-thickness oscillator.
• the deflection A of the thickness vibration is shown schematically in a diagram.
• the x-axis corresponds to the longitudinal direction
• the y-axis corresponds to the deflection of the oscillating structure.
• the deflection corresponds to half the wavelength of the oscillation.
• the maximum deflections occur at the respective ends Xi, x 2 of the vibrating structure 110.
• the deflection is essentially zero, corresponding to one
• metals such as e.g. Aluminum or stainless steel. It is also possible to use plastics which ideally have no glass transition temperature in the temperature range from -40 ° C to + 85 ° C. A combination of different materials is also possible.
• the length of the rod-shaped element is dependent on the choice of the transmission frequency and the material used for the rod-shaped element 145 and the associated
• Propagation speed of sound waves to choose. To avoid inclinations of the rod-shaped element 145, especially when the rod-shaped
• Element 145 is very long compared to the dimensions of the plate 240 or the membrane 120, the rod-shaped element 145 can be fixed by a further bearing structure 175 to the housing 180.
• the bearing structure 175 may preferably be arranged at half the height h of the rod-shaped element 145. This central position of the bearing structure 175 is chosen because there the
• Oscillation amplitude of the thickness vibrations is minimal.
• the position corresponds to the vibration node at the position x m in the illustration according to FIG. 4.
• the membrane 120, the rod-shaped element 145, the housing 180 and the plate 240 are separate
• the membrane 120 and the rod-shaped element 145 may also be formed in one piece.
• the membrane 120 may be integrally formed with the housing 180 and / or the housing 180 may be formed integrally with the panel 240 and the trim member 200, respectively.
• FIG. 2 shows a second embodiment of an electroacoustic transducer 1 is shown schematically in longitudinal section.
• the basic structure and function of the electroacoustic transducer 1 corresponds to that in FIG. 1
• the piezoelectric element 150 is smaller than the membrane 120 in this embodiment, the piezoelectric element 150 is mounted centrally on the underside of the diaphragm 120.
• the membrane 120 and the rod-shaped element 145 are integrally formed.
• the electroacoustic transducer 1 shown in Figure 2 additionally comprises means 148, 248 for mounting aid of
• a recess 148 is formed centrally on the end face 146 of the rod-shaped element 145 as an assembly aid element.
• the plate 240 on its surface 146 facing the end surface 146 has a projection 248.
• Deviations in the positioning can lead to undesirable deviations in the emission characteristic and / or resonance frequency of the electroacoustic transducer 1, in particular, non-centric force discharges can occur in the structures involved, as a result of which undesired so-called “secondary vibrations" can arise in other coordinate directions.
• FIG. 3 shows a third embodiment of an electroacoustic transducer 1 is shown schematically in longitudinal section.
• the basic structure and function of the electroacoustic transducer 1 corresponds to that in FIG. 1
• the rod-shaped member 145 is formed so as to be in the direction of that with the diaphragm 120
• the connected first surface 141 has decreasing cross-sectional area.
• the rod-shaped element 145 is tapered in the direction of its end connected to the diaphragm 120.
• the plate 240 facing the end of the rod-shaped element tapering.
• Connecting surface between the rod-shaped element 145 and the diaphragm 120 and the plate 140 is annular. This achieves a further reduction in the obstruction of vibrations of the diaphragm 120 and the plate 240.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Multimedia (AREA)
• Mechanical Engineering (AREA)
• Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Transducers For Ultrasonic Waves (AREA)

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Citations (1)

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• 2013
  • 2013-06-20 DE DE102013211630.6A patent/DE102013211630A1/de not_active Withdrawn
• 2014
  • 2014-05-26 CN CN201480035379.8A patent/CN105324186A/zh active Pending
  • 2014-05-26 US US14/900,447 patent/US9763009B2/en active Active
  • 2014-05-26 EP EP14727793.3A patent/EP3010655A1/de not_active Withdrawn
  • 2014-05-26 WO PCT/EP2014/060763 patent/WO2014202335A1/de active Application Filing

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