GB2486560A - Piezoelectric sound element - Google Patents

Piezoelectric sound element Download PDF

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Publication number
GB2486560A
GB2486560A GB1121444.2A GB201121444A GB2486560A GB 2486560 A GB2486560 A GB 2486560A GB 201121444 A GB201121444 A GB 201121444A GB 2486560 A GB2486560 A GB 2486560A
Authority
GB
United Kingdom
Prior art keywords
sound
fixing
fixing element
sound transducer
mass
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.)
Granted
Application number
GB1121444.2A
Other versions
GB201121444D0 (en
GB2486560B (en
Inventor
Martin Abele
Karl Bendel
Andre Gerlach
Marko Liebler
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB201121444D0 publication Critical patent/GB201121444D0/en
Publication of GB2486560A publication Critical patent/GB2486560A/en
Application granted granted Critical
Publication of GB2486560B publication Critical patent/GB2486560B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/521—Constructional features
    • 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
    • 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
    • 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
    • G10K11/002—Devices for damping, suppressing, obstructing or conducting sound in acoustic devices
    • H01L41/08—
    • H01L41/09—
    • 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
    • H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
    • H04R1/028—Casings; Cabinets ; Supports therefor; Mountings therein associated with devices performing functions other than acoustics, e.g. electric candles
    • 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
    • H04R17/02—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
    • H04R17/10—Resonant transducers, i.e. adapted to produce maximum output at a predetermined frequency
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • 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
    • H04R2499/13—Acoustic transducers and sound field adaptation in vehicles

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Mechanical Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Multimedia (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

The sound transducer 1 comprises at least one piezoelectric element 10, a fixing element 12 and a mass element 16. The fixing element 12 is attached to a fixing plane 20. The fixing element 12 is in the form of a resilient or flexible spring element, and it may have a region of reduced cross-section 12.1. The piezoelectric element 10 is in contact with both the fixing element 12 and the mass element 16, so that resonant oscillation behaviour of the sound transducer can be generated. A further embodiment (fig 3) shows the piezoelectric element connected to the sides of the fixing element 12 and the mass element 16 rather than lying between them. The sound transducer may be used to detect or generate sound and it may be used in an array.

Description

Sound transducer with at least one piezo element
Description
The invention concerns a sound transducer with at least one piezo element and one fixing element, the fixing element being connected to a fixing plane, according to the pre-characterizing clause of Claim 1.
Prior art
From published specification EP 1 791 192 El, a sound transducer with at least one bending actuator element in the form of a strip or plate is known. It is coated on one side with a piezoelectric body, and has a piezoelectrically inactive multilayer base body. The base body is in the form of a carrying element for a piezoelectric body which is attached to one side of it. Both the carrying element and the base body can have one or multiple layers. However, it has been shown to be disadvantageous that a sound transducer with such a structure is not very robust against humidity, dust, spray, ice, snow or mechanical effects, since the piezoelectric body is connected directly to the base body. Thus fitting the sound transducer externally, e.g. for motor vehicles or robots with direct exposure to environmental effects, is unsuitable for lasting, reliable functioning.
Disclosure of the invention
It is thus the object of the invention to create an improvedsound transducer which because of its construction ensures lasting, secure and high operational reliability when it is used externally, e.g. attached to the exterior of a motor vehicle. -To achieve this object, a sound transducer according to the features of Claim 1, in particular with the features of the characterizing part, is proposed. In the dependent claims, preferred further developments of the invention are explained.
According to the invention, it is provided that the fixing element is in the form of a spring element, and the sound transducer has a mass element, the piezo element contacting the fixing element and the mass element, so that resonant oscillation behaviour of the sound transducer can be generated. The sound transducer according to the invention can act as both sound transmitter and sound receiver. The piezo element converts electrical voltages into mechanical deformations, and vice versa. The sound transducer on the one hand outputs, and on the other hand receives, these mechanical deformations as sound waves.
The core of the invention is that the piezo element is not connected directly to the fixing plane. Thus the piezo element, with the fixing element and mass unit, forms one unit, the oscillation behaviour of which can be influenced by selection of specified elements. The piezo element can be protected from external environmental influences, e.g. mechanical stresses, and from exposure to humidity, dust, spray, ice, snow or similar, since only the sound-active surface must be exposed directly to the environment. This structure also provides the advantage that at least two S sound transducers can be arranged so that the distance between them is less than half the wavelength of sound in air. This is then called an array arrangement, which can provide extended possibilities in signal processing. For an ultrasound frequency of, for example, 50 KHz, the wavelength of sound in air is about 7 mm. This means that the sound transducers can be about 3.5 mm at maximum from each other. This maximum distance limits the size of the sound transducers, which can be produced by the structure according to the invention. Because of the size limitation for array transducers, today mainly MEMS (micro-electro-mechanical system) elements are used for air ultrasound arrays. However, such MEMS elements are not very robust against humidity, dust, spray, ice, snow or mechanical effects, as already described.
It is specially advantageous that the mass element has a plane sound-active surface. The sound-active surface can be in the form of a triangular, rectangular or circular elevation. Other geometrical shapes are also conceivable.
Depending on the shape of the surface, different emission behaviour of the sound transducer can be made possible. The height of the elevation can also be variable, so that tile sound-active surface can be deducted from the fixing element. The advantage of this is that a protective screen which has an opening, which is in complementary shape to the shape of the sound-active surface, can be used. In this way, the piezo element can be protected, and it is possible to decouple the piezo element from the sound-active surface, so that interfering environmental influences come into contact with the sound-active surface only directly.
It has also been proved to be advantageous that the mass element and the fixing element can be arranged in the form of rods. The mass element and the fixing element can have the same cross-section and also the same geometrical shape, in particular circular or rectangular. Any other geometrical shapes are also conceivable. The rod-shaped structure also makes it possible, in an arrangement of multiple sound transducers, to arrange their sound-active surfaces directly next to each other. The whole arrangement of the mass element and fixing element can also be in the form of a truncated cone. The piezo element can also be arranged between the fixing element and the mass element.
In this case, the third dimension of the rod-shaped sound transducer is significantly longer, so that working with the rigid fixing plane, resonant oscillation behaviour can be set up. If multiple sound transducers next to each other are used o that a linear array can be set up, it is advantageous that the width of a piezo element is not greater than that of the fixing element. In this way, the ultrasound transducers can be connected directly to each other, so that technical implementations the dimension of which can be less than or equal to half the wavelength of sound in air are possible. Limiting the sound-active surface in a second dimension makes it possible to use linear arrays or linear arrays with additional elements.
Fixing elements for fixing to a fixing plane which is resistant to bending and of suitable dimensions can also be used.
It is also advantageous that the cross-section of the fixing element is reduced locally, the result being a constriction. In this way, the fixing element can be in the form of a spring element. When the fixing element is connected to the fixing plane, which can be implemented so that it is resistant to bending, a resonant oscillation behaviour can be created in interaction with the mass element. Formation of the fixing element as a spring element dan also be achieved by selecting a less rigid material, in particular a plastic.
It is alsc advantageous that the sound-active surface is flat or curved or has any 2-dimensional structure. Thus the emission characteristics of the sound transducer can be influenced in a predefined manner. If multiple sound transducers are used, a directional effect can be created with them, for example. Sound-active surfaces which are roughened or provided with a profile are also conceivable, so that the emission characteristic of the sound transducer is also changeable.
A further advantage is that the fixing element has a surface or geometry which is in complementary form to the fixing plane. For example, a groove-spring system can be used, the fixing plane having a groove and the fixing element having a spring which is in complementary form to the groove. In this way, before the actual final connecting process, e.g. by an adhesive or welding method, the fixing element can be fixed to the fixing plane. Also, the fixing element can have a hole, and the fixing plane can have pins in complementary shape to it, so that fixing the fixing element to the fixing plane can also be achieved.
It is advantageous that the mass element and/or the fixing S element have metal, in particular light metal, ceramic or plastic. In this way, the oscillation behaviour of the sound-active surface can be changed corresponding to the requirements. Furthermore, simplified production of both elements, the mass element and the fixing element, is achievable. In this way, the oscillation behaviour can also be influenced according to what material is used.
It is also advantageous that the fixing element and the mass element can be produced from uniform or different materials. Thus different oscillation behaviours can be made possible by different use of different materials. If the fixing element and the mass element are made of uniform materials, inexpensive, simple production is possible. By making the fixing element and the mass element of different materials, the oscillation behaviour of the sound transducer can be influenced in a simple, defined manner by the selection of materials. It is also conceivable that the mass element and the fixing element are executed in one piece. The fixing element can then be attached to the fixing plane by an adhesive or welding method.
A further preferred embodiment consists of an array arrangement with at least two sound transducers according to the invention, the distance between the sound transducers being less than half the wavelength of sound in air which can be imitated via the plane sound-active elevation, so that a dynamically changed ultrasound beam can be generated. In this way, in transmission operation, a large sound pressure level can be generated. In reception operation, a high sensitivity to sound is thus ensured.
Thus resonantly working air sound transducers with a working frequency in the range of 48 1KHz can be provided, and are suitable for an array arrangement and also specially robust against external environmental influences.
The working frequency of 48 1KHz is specially suitable for ultrasound-based environment sensing, since the frequency position is above typical interfering sound sources, and the air absorption is not yet too great, animals being hardly disturbed.
In the array arrangement, the sound transducer according to the invention can be produced from metals, ceramic or plastic, together with one, two or more piezo elements.
Because of the chosen materials and the minimum dimensions, with which it is possible to comply, these transducer elements are robust against mechanical and other environmental effects. Two piezo elements can be combined in such a way that the sound transducer, compared with sound transducers with one piezo element, obtains special properties, which can be used singly or in combination.
These are characterized by increased effectiveness of the sound emission and/or increased sensitivity in the case of sound reception.
Fast switching between transmission operation and reception operation is also made possible. Self-diagnosis of the oscillation-mechanical properties is also possible.
Further actions and advantages of the invention are given in the claims, the following description and the drawings.
In the drawings, the invention is shown in several embodiments. The features which are mentioned in the claims and the description can be essential to the invention individually or in any combination.
Fig. 1 shows a schematic view of a rod-shaped sound transducer, Fig. 2 shows a schematic view of a rod-shaped sound transducer on a fixing plane, and Fig. 3 shows a schematic view of a sound transducer, with a sound-active surface in the form of an elevation.
In Fig. 1, a rod-shaped sound transducer 1 according to the invention, in an almost horizontal position, is shown schematically. The fixing element 12 is locally reduced in the centre by a constriction 12.1. The rod-shaped transducer 1 has a mass element 14, a discoidal piezo element 10 being arranged between the fixing element 12 and the mass element 14, and the cross-section remaining constant over the height in the above-mentioned connection region. The sound transducer 1 is connected on the invisible underside of the fixing element 12 to a fixing surface 20 (not shown). The mass element 14 also has a sound-active surface 16, which forms the top of the rod-shaped sound transducer 1. In the case of the shown sound transducer 1, the height of the fixing element 12 is almost twice as high as the height of the mass element 14. The whole sound transducer 1 has a rectangular cross-section over its full height.
In Fig. 2, a rod-shaped sound transducer 1, which with its fixing element 12 is connected or joined to a fixing surface 20, is shown. The cuboidal sound transducer 1 has a mass element 14, a discoidal piezo element 10 being arranged between the mass element 14 and the fixing element 12. The whole cross-section of the sound transducer 1 is in geometrically constant form over its whole height. The fixing element 12 consequently has no taper. For the fixing element 12, a less rigid material than that of the fixing surface 20 can be chosen, so that at this position the fixing element 12 is in the form of a yielding spring element. For example, plastics which are less resistant to bending can be considered for this purpose.
In Fig. 3, a further sound transducer 1 according to the invention is shown, the mass element 14 being equipped with a sound-active surface 16 in the form of an elevation. This elevation is in circular form, so that the sound-active surface 16 is also in circular form. The fixing elenent 12 is fixed with its underside on the fixing plane 20. The flat, cuboidal piezo element 10 contacts laterally the mass element 14 and the fixing element 12. However, unlike in the two above-mentioned embodiments from Figs. 1 and 2, the piezo element 10 is not arranged between the two elements 12 and 14. Instead, the mass element 14 is connected directly to the fixing element 12. The cuboidal piezo element 10 is connected laterally to the two elements 12 and 14 with surface symmetry. A deformation starting from the piezo element 10 is thus transmitted from the mass element 14 to the sound-active surface 16, and from there converted into a sound wave. It is also conceivable that the cross-section of the fixing element 12 can be reduced locally, so that a constriction 12.1 can be generated. In this way, the fixing element 12 can be formed as a spring element.
GB1121444.2A 2010-12-14 2011-12-13 Sound transducer with at least one piezo element Expired - Fee Related GB2486560B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102010063001A DE102010063001A1 (en) 2010-12-14 2010-12-14 Sound transducer with at least one piezoelectric element

Publications (3)

Publication Number Publication Date
GB201121444D0 GB201121444D0 (en) 2012-01-25
GB2486560A true GB2486560A (en) 2012-06-20
GB2486560B GB2486560B (en) 2017-02-22

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GB1121444.2A Expired - Fee Related GB2486560B (en) 2010-12-14 2011-12-13 Sound transducer with at least one piezo element

Country Status (3)

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DE (1) DE102010063001A1 (en)
FR (1) FR2968820B1 (en)
GB (1) GB2486560B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014202331A1 (en) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Surroundings-sensing system having an ultrasonic transducer, and a motor vehicle having such a surroundings-sensing system
WO2014202249A1 (en) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Ultrasound transducer assembly and motor vehicle having an ultrasound transducer assembly
US20160139250A1 (en) * 2013-06-20 2016-05-19 Robert Bosch Gmbh Surroundings-sensing device having a modular ultrasonic transducer, and motor vehicle having such a surroundings-sensing device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016200657A1 (en) * 2016-01-20 2017-07-20 Robert Bosch Gmbh Transducer array

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0098017A2 (en) * 1982-06-28 1984-01-11 Magnavox Government and Industrial Electronics Company End weighted reed sound transducer
US5867450A (en) * 1996-11-07 1999-02-02 Georgia Tech Research Corporation State switched acoustic transducer
WO2000045444A1 (en) * 1999-01-29 2000-08-03 Ritchter Hans Drive device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE502005003241D1 (en) 2005-11-25 2008-04-24 Festo Ag & Co Piezoelectric bending transducer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0098017A2 (en) * 1982-06-28 1984-01-11 Magnavox Government and Industrial Electronics Company End weighted reed sound transducer
US5867450A (en) * 1996-11-07 1999-02-02 Georgia Tech Research Corporation State switched acoustic transducer
WO2000045444A1 (en) * 1999-01-29 2000-08-03 Ritchter Hans Drive device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014202331A1 (en) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Surroundings-sensing system having an ultrasonic transducer, and a motor vehicle having such a surroundings-sensing system
WO2014202249A1 (en) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Ultrasound transducer assembly and motor vehicle having an ultrasound transducer assembly
CN105324187A (en) * 2013-06-20 2016-02-10 罗伯特·博世有限公司 Ultrasound transducer assembly and motor vehicle having an ultrasound transducer assembly
US20160139250A1 (en) * 2013-06-20 2016-05-19 Robert Bosch Gmbh Surroundings-sensing device having a modular ultrasonic transducer, and motor vehicle having such a surroundings-sensing device
US9962738B2 (en) 2013-06-20 2018-05-08 Robert Bosch Gmbh Ultrasonic transducer system and motor vehicle including an ultrasonic system
CN105324187B (en) * 2013-06-20 2018-11-20 罗伯特·博世有限公司 Ultrasound transducer assembly and motor vehicle with ultrasound transducer assembly

Also Published As

Publication number Publication date
GB201121444D0 (en) 2012-01-25
FR2968820A1 (en) 2012-06-15
GB2486560B (en) 2017-02-22
FR2968820B1 (en) 2019-04-12
DE102010063001A1 (en) 2012-06-14

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20221213