GB2491977A - Piezoelectric ultrasonic transducer with connections to printed circuit board arranged to minimise interference - Google Patents
Piezoelectric ultrasonic transducer with connections to printed circuit board arranged to minimise interference Download PDFInfo
- Publication number
- GB2491977A GB2491977A GB1210631.6A GB201210631A GB2491977A GB 2491977 A GB2491977 A GB 2491977A GB 201210631 A GB201210631 A GB 201210631A GB 2491977 A GB2491977 A GB 2491977A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit board
- printed circuit
- diaphragm pot
- leads
- piezoelectric element
- 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
Links
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- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
- G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices
-
- 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
- G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
- G01S7/52079—Constructional features
-
- 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
- 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
-
- 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
- G10K9/18—Details, e.g. bulbs, pumps, pistons, switches or casings
- G10K9/22—Mountings; Casings
-
- 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
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/93—Sonar systems specially adapted for specific applications for anti-collision purposes
- G01S15/931—Sonar systems specially adapted for specific applications for anti-collision purposes of land vehicles
Abstract
An ultrasonic transducer comprises a piezoelectric element 10, with a printed circuit board 20 and with a diaphragm pot 30. The piezoelectric element is attached to the front face 32 of the diaphragm pot and connected via at least two leads 40,42 to signal connection points 22 of the printed circuit board 20. In one arrangement a portion 24 of the circuit board projects into the diaphragm pot. The portion of the PCB may be smaller in width than the clear width of the diaphragm pot, and the remainder of the PCB may be arranged outside the pot. Alternatively the leads 40,42 (e.g. wires, single core cables) are arranged so that they run with a spacing from one another which is smaller than half the width of the piezoelectric element, preferably no more than the electrode gap width of the element 10. The transducer may be attached to a panel of a motor vehicle and used as a distance sensor . The distance sensor includes the ultrasonic transducer and also an acoustic damping ring 72 and a housing 70.
Description
Ultrasonic transducer with piezoelectric element and distance sensor State of the Art From automotive applications, in particular, it is known to register a spacing from an object by means of pulse-echo processes. One approach is to emit scanning pulses by means of an ultrasonic transducer, to receive the echoes back, and to perform a spacing calculation from the delay-time, use being made of a piezoelectrjc element by way of transducer element.
Ultrasonic transducers of such a type are mounted within distance sensors in the panelling of a motor vehicle, in order, for example, to realise parking aids or collision-warning systems.
The piezoelectric elements are used, in particular, for receiving the ultrasonic echoes, with voltages of a few microvolts being generated by the piezoelectric element.
Given such a signal strength, even small electromagnetic disturbances result in a significant impairment of the quality of the signal.
Furthermore, from DE 102 61 033 Al, for example, connecting structures are known that are based on multi-core cabling, this involving, however, complex steps in the course of automated production.
It is therefore an object of the invention to make possible an ultrasonic transducer and a distance sensor that are both interference-resistant and capable of being produced in straightforward manner.
Disclosure of the Invention
This object is achieved by virtue of the ultrasonic transducer according to Claim 1, by virtue of the distance sensor according to Claim 11, and by virtue of the process according to Claim 13.
The ultrasonic transducer according to the invention and the distance sensor according to the Invention can be produced by simple automated steps. In particular, use is made of components that can be handled in straightforward manner and that, in addition, are inexpensive. Moreover, the invention can be realised by simple modification of existing device elements. Lastly, the ultrasonic transducer according to the invention and the distance sensor according to the invention are mechanically stable, particularly in relation to vibrations.
The ultrasonic transducer according to the invention exhibits a metallic diaphragm pot, on the front face of which a piezoelectric element is attached. It has been * recognised by the inventors that, in particular, the * connection between the piezoelectric element and a processing circuit is critical for the quality of the signal. Furthermore, it has been recognised by the inventors that *the interior space of the diaphragm pot itself is sufficiently protected in relation to -3-.
electromagnetic radiation, whereas the routing of the leads outside the diaphragm pot is critical for the quality of the signal. Therefore the concept underling the invention is to keep the area between the leads, in particular outside the diaphragm pot, as small as possible, so that interference fields in the form of alternating magnetic fields induce only a slight interference signal, or one that can be neglected, in the leads. Therefore the area between the leads is diminithed by the linear path of the leads outside the diaphragm pot being minimised, by the spacing between the leads being minimised, or by both the linear path and the spacing being minimised. It is inirnediately evident that, as a result, the magnetic flux of magnetic interference fields is likewise mininiised by reason of the minimised area.
The invention therefore relates to an ultrasonic transducer with a piezoelectric element, with a diaphragm pot and with a printed circuit board, the piezoelectric element being attached on a front inner surface of the diaphragm pot.
The ultrasonic transducer exhibits a preferentially metallic diaphragm which is arranged on a front face of the diaphragm pot. The front face is provided at a position situated remotely with respect to the printed circuit board. The piezoelectric ceramics of the piezoelectric element are attached on the diaphragm, in particular on the side of the diaphragm, which is located on the front face, directed towards the interior space of the diaphragm pot.
On the front face the ultrasonic transducer forms a sensitive sensor surface which corresponds, in particular, to the surface of the diaphragm that faces away from the printed circuit board. The piezoelectric element and the diaphragm form an acoustic unit. The diaphragm may have -4-.
been formed in one piece with the diaphragm pot or may have been connected to the latter in positive or force-cldsed manner. The piezoelectric element is furthermore connected via at least two leads to signal connection points of the printed circuit board which acoustically insulate the piezoelectric element from the printed circuit board.
The minimisation, according to the invention, of electromagnetic interference signals is obtained by the signal connection points of the printed circuit board being provided on a portion of the printed circuit board that protrudes into the diaphragm pot. In other words, the signal connection points of the printed circuit board are located within the diaphragm pot. The routing of the signal, starting from the signal connection points on the printed circuit board, can be provided with particularly low susceptibility to interference. For this purpose the signals stemming from the piezoelectric element, for example, are routed by means of conductor tracks situated closely together, whereby these conductor tracks may run, in particular, on top of one another in differing layers of the printed circuit board. As a further measure for reducing the susceptibility to interference, the leads run with a spacing from one another that over substantially the entire course of the leads is smaller than half the width of the piezoelectric element. By virtue of the close routing of the leads the susceptibility to interference is likewise reduced. In particular, there may be provision that both of the aforementioned measures are combined with one another. The piezoelectric element takes the form, in particular, of a flat body, with the width relating to the principal direction of extent of the body. The piezoelectric element is preferentially a round, in -5-.
particular circular, flat disc, with half the width corresponding to the radius of the disc.
According to one embodiment of the invention, the at least two leads have been di±ectly connected to the signal connection points of the printed circuit board. As an alternative to this, the at least two leads may have been connected to contact elements of a contact carrier. Via this contact carrier the piezoelectric element has been electrically connected to the signal connection points of the printed circuit board. In particular, the at least two leads may have been connected to contact points of the contact elements that are situated within the diaphragm pot. In the aforementioned case the contact elements protrude into the diaphragm pot.
The leads are each implemented in the form of wires or in the form of single-core stranded cables. One embodiment of the invention may provide that at least one of the leads is surrounded by an external insulating layer. The ends of the leads are preferentially not covered by the external insulating layer. However, in particularly preferred manner the leads take the form of wires that either bear no insulating layer or are surrounded by a layer of lacquer by way of insulating layer. The leads are acoustically insulating in their longitudinal direction and do not form an acoustic bridge.
The diaphragm pot has been produced from an electrically conducting material. This material may be metal or an alloy. Furthermore, the electrically conducting material may be a composite material that includes a metal or an alloy. In a specific embodiment the diaphragm pot consists of aluminium. The electrically conducting material of the diaphragm pot is configured in the form of a surface-conducting conductor structure. A conductor structure of such a type is preferentially a continuously conducting surface consisting of electrically conducting material. In specific embodiments a conductor structure of such a type may be a grid consisting of conducting material, the grid preferentially being provided in close-meshed form with a mesh width of less than 5 mm, 3 mm, 2 mm or 1. mm, and the grid acting in shielding manner in relation to electromagnetic perturbing influences. By way of electrically conducting material, in particular material with a specific conductivity of at least 106 SJm or at least io S/rn is used.
The piezoelectric element may furthermore exhibit an electrode surface that is electrically connected to the diaphragm pot. As a result, the electrode surface is electrically connected to the diaphragm pot. The electrode surface is preferentially earthed. As a result, the diaphragm pot constitutes a protection against perturbing influences. In particular, a diaphragm is provided on the front face of the diaphragm pot, which with the piezoelectric ceramics of the piezoelectric element forms an acoustic unit. The diaphragm is electrically conducting and, in particular, formed from metal or from an alloy, in order to act in shielding manner in relation to electromagnetic perturbing influences. The diaphragm closes off the diaphragm pot. The diaphragm is electrically connected to the diaphragm pot.
A specific embodiment of the invention relates to an embodiment in which the portion of the printed circuit board on which the signal connection points of the printed circuit board have been formed takes the form of a projection. The projection exhibits a width that is smaller than the clear width of the diaphragm pot on a rear face of the diaphragm pot. The rear face of the diaphragm pot is opposed to the front face. The projection can readily be introduced into the diaphragm pot from the rear face, in order to bring the signal connection points of the printed circuit board closer to the piezoelectric element.
The printed circuit board further exhibits a pcb base, away from which the projection extends. The pcb base and the projection are formed by one and the same printed circuit board. The pcb base and the projection are consequently integrally formed. The pcb base is wider than the clear width of the diaphragm pot on the rear face. The pcb base is arranged outside the diaphragm pot. The pcb base and the projection extend in the same plane.
A further embodiment, in which the leads run with a small spacing from one another, provides that the spacing between the leads is not greater than half the width of the piezoelectric element or amounts to no more than 3 mm, 2 mm or 1 mm. Moreover, the spacing may amount to no more than one electrode-gap width of the piezoelectric element, inclusive of a contact-point width of the piezoelectric element. The electrode-gap width is the width of the electrode gap that exists between electrode surfaces of the piezoelectric element. The width of the electrode gap is determined, on the one hand, by the technology with which the piezoelectric ceramics and the electrode are produced, on the other hand by the drive voltages for the piezoelectric ceramics. If the electrode gap is too small, voltage breakdowns may occur between the electrodes. The contact-point width arises, in addition, also by virtue of the thickness of the wire and by virtue of the contact technique being used, and ordinarily amounts to no more than 0.25 mm, no more than 0.5 mm or no more than 1 mm.
Moreover, there may be provision that the leads between the front face and the signal connection points run parallel to one another. The leads have been connected to differing electrode surfaces of the piezoelectric element on contact points of the electrode surface that are separated by an electrode gap. In this case the contact points on which the leads are arranged on the respective electrode surfaces of the piezoelectric element are situated opposite one another at the electrode gap.
All the contact points of the pie2oelectric element are preferentially situated on one side of the piezoelectric element. In this case the contact points via which all the leads have been connected to the piezoelectric element are situated on one and the same side. The contact points are situated, in particular, on the side of the piezoelectric element that faces towards the printed circuit board. This side of the piezoelectric element, on which all the contact points are arranged, faces towards the interior of the diaphragm pot. On the front face of the diaphragm pot an outside of the piezoelectric element that bears no contact points is consequently located, in particular the diaphragn of the ultrasonic transducer.
A further embodiment of the ultrasonic transducer provides that the leads have been electrically connected to the printed circuit board and/or to the piezoelectric element via thermocompression-welding contacts, via solder contacts or via other material-closure contacts. The contact points on the electrode surfaces of the piezoelectric element are consequently formed by contacts that have been formed by soldering or by thermocompression welding. Moreover, the at least two leads are directly connected to the signal connection points of the printed circuit board via contact points that are generated by therrnocompression welding, by soldering or by other material-closure connection techniques. Furthermore, the two leads may have been connected to contact elements of a contact carrier via contact points that are situated on the contact elements of the contact carrier and that are likewise generated by means of thermocompression welding, soldering or by means of other material-closure connection techniques. As a further material-closure connection technique that is suitable for implementing the invention, resistance welding, for example, is to be mentioned. The material- closure contacts arising are designated as resistance-welding contacts.
Lastly, there is provision that the printed circuit board runs in a longitudinal direction that corresponds to the direction of extent of the diaphragm pot and/or to the direction of extent of the leads. In particular, the diaphragm pot may exhibit a longitudinal axis that is situated within the printed circuit board. Furthermore, however, the printed circuit board may have been radially offset with respect to the longitudinal axis of the diaphragm pot, so that the printed circuit board runs parallel tc the longitudinal axis of the diaphragm pot.
Finally, the contact elements of the contact carrier may also run in accordance with the direction of extent of the diaphragm pot. In this case the contact elements extend, -o-at least in sections, parallel to the longitudinal axis of the diaphragm pot, whereby, furthermore, a contact element of a contact carrier may extend, at least in sections, along the longitudinal axis of the diaphragm pot. The direction of extent corresponds, in particular, to the direction in which the longitudinal axis of the diaphragm pot runs.
The diaphragm pot exhibits a circular cross section but it may also exhibit other cross sections. In particular, the cross section of the diaphragm pot along the. longitudinal extent of the diaphragm pot is constant, so that the side wall of the diaphragm pot is cylindrically formed. In order to obtain desired acoustic effects, the interior of the diaphragm pot may have, been foamed, at least partly, by means of an acoustic damping foam. In particular, an internal portion of the diaphragm pot has been filled out with an acoustic damping foam which directly adjoins the piezoelectric element. Furthermore, acoustic damping foam is used in order to insulate the diaphragm pot acoustically in relation to the printed circuit board and in order tc fix the printed circuit board locally in relation to the diaphragm pot.
The invention further relates to a distance sensor that has been set up for attachment within a panel of a motor vehicle. For this purpose an external fastening element may have been provided. The distance sensor includes the ultrasonic transducer according to the invention as described herein. The distance sensor further includes an acoustic damping ring. The distance sensor includes, in addition, a housing. The diaphragm pot of the ultrasonic transducer has been connected to the housing via the -"-damping ring. The damping ring, in particular consisting of acoustically insulating damping foam, insulates the diaphragm pot in relation to the housing in acoustic respects and fixes the diaphragm pot locally in relation to the housing. The front face of the diaphragm pot protrudes from the housing. The positional indications at the rear' and at the front' relate to the diaphragm pot in its longitudinal extent, with the positional indication at the rear' relating to a position close to the printed circuit board, and the positional indication at the front' relating to a position situated remotely with respect to the printed circuit board.
On the printed circuit board, in particular on the base of the printed circuit board, a signal-conditiOning circuit is provided which exhibits terminals for the piezoelectric + element. The leads have been connected to these terminals, in particular via conductor tracks of the printed circuit board. In this case the terminals of the signal-conditioning circuit have been connected to the signal connection points via conductor tracks of the printed circuit board, the conductor tracks preferentially being laterally spaced from one another by no more than 1 mm or 2 mm. A preferred embodiment of the invention provides that the conductor tracks to which the signal connection points of the printed circuit board have been linked are situated on top of one another and are only separated by an insulating layer which forms one layer of the printed circuit board. The conductor tracks are consequently preferentially provided by conductor layers that run in plane-parallel manner relative to one another in or on the printed circuit board. On the printed circuit board a transmitting circuit, set up for generating an electrical pulse signal, may furthermore have been provided, which has been connected to the terminals for the piezoelectric element in order to drive the piezoelectric element with the electrical pulse signal.
The invention further encompasses a process for producing an ultrasonic transducer, in particular an ultrasonic transducer as described herein. The process comprises the following steps: provision of a piezoelectric element, of a printed circuit board and of a diaphragm pot. These components preferentially correspond to the components described herein. The printed circuit board is provided with signal connection points, for example by means of lithographic etching processes. The piezoelectric element is attached on a front face of the diaphragm pot. In this case a unit consisting of the piezoelectric ceramics of the piezoelectric element and a diaphragm is formed on the front face of the diaphragm pot, by the piezoelectric ceramics and the diaphragm being adhesion-bonded together, in particular on a side of the diaphragm that faces towards the interior of the diaphragm pot. The piezoelectric element is connected via at least two leads to the signal connection points of the printed circuit board, in particular by means of a welding process, for example by means of a thermocompression-welding process or a resistance-welding process. The aforementioned step of welding is implemented, in particular, after the leads are electrically connected to the piezoelectric element, for example by means of soldering or by means of a welding process as named above. The provision of the printed circuit board includes making the signal connection points of the printed circuit board available on a portion of the printed circuit board that is introduced into the interior of the diaphragm pot. The printed circuit board is fixed in relation tothe diaphragm pot, in particular by means of an acoustically insulating connection, for example by foaming with an acoustically insulating damping foam.
Alternatively, the leads are attached to the signal connection points, whereby by virtue of the attachment the leads are routed with a spacing from one another that over substantially the entire course of the leads is smaller than the radibs of the piezoelectric element. By virtue of the routing of the leads, the latter are arranged with respect to one another as described above.
Brief Description of the Drawings
Figure 1 shows a first embodiment of the ultrasonic transducer according to the invention within a distance sensor according to the invention and Figure 2 shows a second ernbcdiment of the ultrasonic transducer according to the invention within a distance sensor according to the invention Embodiments of the Invention Figure 1 shows an ultrasonic transducer according to the invention with a piezoelectric element 10, with a printed circuit board 20 and with a diaphragm pot 30. The piezoelectric element 10 has been secured in place with adhesive on a front face 32 of the diaphragm pot 30, preferentially by means of a diaphragm which, after the bonding, forms a unit with the piezoelectric element 10.
The printed circuit board 20 carries two signal connection points 22 which have been provided by way of surface conductors. The signal connection points 22 are arranged on a portion 24 of the printed circuit board 20 that protrudes into the diaphragm pot 30. The portion 24 takes the form of a projection of the printed circuit board 20.
The piezoelectric element 10 has been connected to the signal connection points 22 via two leads 40, 42.
The piezoelectric element 10 includes electrode surfaces 12, 14, between which an electrode gap with an electrode-gap width 16 is formed. On the differing electrode surfaces 12, 14 of the piezoelectric element 10 there have been formed contact points 50, 52, via which the leads 40, 42 have been connected to the electrode surfaces 12, 14.
In like manner, on the signal connection points 22 there are located contact points 54, 56, via which the leads 40, 42 have been connected to the signal connection points 22 of the printed circuit board. It is evident that the contact points 50, 52 are only separated from one another by the electrode-gap width 16 and are situated as closely as possible alongside one another. In like manner the signal connection points 22 of the printed circuit board 20 are only slightly spaced from one another, for example with a spacing that corresponds to the electrode-gap width 16.
As a result, the leads 40, 42 run parallel to one another with a slight spacing, for example approximately 1 mm or less.
The printed, circuit board 20 includes a portion 24 which protrudes into the diaphragm pot 30 and extends through the rear face 34. This portion 24 takes the form of a projection of the printed circuit board 20, i which connection a pcb base 26 formed in one piece therewith is wider than the diaphragm pot 30. The portion 24 of the printed circuit board 20 is, however, narrower than the inner width of the diaphragm pot 30. On the pcb base 26 there is located a signal-conditioning circuit 28 which has been connected to the signal connection points 22 via conductor tracks. The conductor tracks form a schematically represented electrical connection 60.
The distance sensor represented in Figure 1 further includes a housing 70 and also a damping ring 72, via which the housing has been connected to a peripheral outside of the diaphragm pot 30. Both the housing 70 and the damping ring 72 have been represented merely schematically. The damping ring is preferentially formed from an elastic material, in order to damp vibrations acoustically, in particular from acoustic damping foam.
In Figure 1 a first routing of leads has been represented by continuous lines, wherein two leads 40, 42 are spaced from one another only by the electrode-gap width 16 and with this spacing are also connected to the respective signal connection points 22 of the printed circuit board 20 via the contact points 54, 56. A further possible embodiment of the invention has been represented by dashed lines, wherein two leads 40', 42' have been connected to electrode surfaces 12, 14 of the piezoelectric element 10 via contact points 51 and 52. Owing to their production process, the contact points 51 and 52 exhibit a relatively large spacing from one another. Nevertheless, a slight susceptibility to interference is obtained, since the portion 24', represented in dashed manner, of the printed circuit board 20 protrudes into the diaphragm pot 30. On this portion 24' there are located two contact points 54', 56' which have been connected to the signal-conditioning circuit 28 via an electrical connection (not represented) The contact points 54', 56', via which leads 40', 42' have been connected to the printed circuit board. 20, also exhibit a relatively large spacing from one another, particularly in comparison with the spacing between the contact points 54 and 56. Nevertheless, a slight susceptibility to interference is guaranteed, since the contact points 54', 56' have been provided within the diaphragm pot 30 and the electrical connections between the contact points 54' and 56', on the one hand, and the signal-conditioning circuit 28, on the other hand, can be provided by conductor tracks that exhibit a distinctly smaller spacing from one another, for example a spacing of no more than 3 mm, 2 mm or 1 mm.
From examination of the routing of signals between the contact points 50, 52, on the one hand, and the contact points 54, 56, on the other hand, it is evident that, as a result, the leads 40 and 42 automatically exhibit a slight, minimal spacing from one another. From examination of Figure 1 it can therefore be discerned that the minimal susceptibility to interference according to the inventicn is also obtained if the contact points 54 and 56 were to be located outside the diaphragm pot 30 and consequently a portion of the leads 40, 42 were to be located outside the diaphragm pot 30. Since in such a portion the spacing between the leads 40 and 42 is minimised, a minimal area between the leads outside the diaphragm pot 30 also arises which would be susceptible to influences of electromagnetic disturbance.
The leads 40, 40' and 42 are acoustically insulating.
Furthermore, the printed circuit board 20 is acoustically insulated in relation to the diaphragm pot 30, for example by means of an acoustic damping material, in particular a foam material.
S
In Figure 2 a second embodiment of the distance sensor according to the invention has been represented which includes an ultrasonic transducer according to the invention. Components of Figure 1 correspond to those components of Figure 2 which exhibit, except for a leading one', the same reference symbols as in Figure 1. The distance sensor of Figure 2 includes a piezoelectric element 110 with electrode surfaces 112, 114. The electrodes are spaced from one another via an electrode gap with an electrode-gap width 116. The ultrasonic transducer represented in Figure 2 further includes a diaphragm pot with a front face 132. On this face there extends a diaphragm which with the piezoelectric ceramics of the piezoelectric element forms an acoustic unit. Furthermore, the embodiment shown in Figure 2 includes a printed circuit board 120 which has been represented merely schematically.
On the printed circuit board 120 a signal-conditioning circuit 128 is arranged.
t'1ithin the diaphragm pot 130 there are arranged leads 140, 142 which at one end have been connected to the electrode surfaces 112, 114 via contact points 150, 152. The opposite end of the leads 140, 142 has been connected to contact elements 180, 182 via contact points 184, 186. The contact elements 180, 182 are part of a contact carrier 190 which includes connector elements 192, 194. The connector elements 192, 194 have been connected to the contact elements 180, 182 via schematically represented connections which preferentially run within the contact carrier 190. A further, schematically represented, electrical connection connects the connector elements 192, 194 to the printed circuit board 120 and consequently to the signal-conditioning circuit 128. The connection between the connector elements 192, 194 and the printed circuit board may be a shielded lead. In particular, the connection between the connector elements 192, 194 and the printed circuit board 120 may include a plug-in connection. The connection between the connector elements 192, 194 and the printed circuit board 120 may be an acoustically coupling connection, whereas the leads 140, 140', 142 and 142' are acoustically insulating.
A routing of leads that represents an alternative to the routing of the leads 140, 142 has been represented by dashed lines. In this case the leads 140' and 142' connect the electrode surfaces 112, 114 to the contact elements 180, 182 via contact points 152, 151. In this case, lead 140' has been connected to electrode surface 112 via a contact point 151 which is situated relatively far away from the contact point 152 which connects lead 142' to electrode surface 114. However, since the leads 140', 142' are still connected within the diaphragm pot 130 to the respective contact elements 180', 182', the leads 140' 142' are protected by the diaphragm pot 130 against perturbing influences. Furthermore, in Figure 2 it is shown that the contact elements 180', 182' have been connected to the connector elements 192, 194, this connection being provided by a schematically represented, dashed electrical * connection. It is evident that, despite the large spacing between the leads 140', 142', the signal transmission from the piezoelectric element 110 to the contact carrier is protected, since the leads 140', 142' run within the diaphragm pot over their entire length.
The ultrasonic transducer represented in Figure 2 is provided partly within a distance sensor which, in addition to the ultrasonic transducer, further includes an acoustic damping ring 172 and a housing 170. The housing 170 forms, as also represented in Figure 1, an interior space in which the printed circuit board 120 and also a rear portion, facing away from the piezoelectric element, of the retaining bush 130 is completely accommodated. In particular, the housing completely encompasses the contact carrier 190, preferentially in the peripheral direction of the diaphragm pot 130. The diaphragm pot 130 is open on one side, in order to be able to introduce the printed circuit board 120. After the positioning of the printed circuit board 120 relative to the diaphragm pot 130, the diaphragm pot 130 is potted with a potting material and cured. In the diaphragm pot 130 a potting material may therefore have been provided which seals the diaphragm pot and fastens the diaphragm pot 130 and the printed circuit board 120 relative to one another. Alternatively or in combination with this, a cover may have been provided which after the poitioning of the printed circuit board 120 is fitted in the diaphragm pot 130 and seals the diaphragm pot 130.
The contact elements 180, 182 are provided completely within the diaphragm pot 130, so that these are also protected in relation to perturbing influences. This holds likewise for the contact elements 180', 182' of the embodiment represented in dashed manner.
The contact carrier 190 has been connected to the diaphragm pot 130 via an acoustic insulation, or itself forms an acoustic insulation. An acoustic insulation of such a type is provided by acoustic damping elements which acoustically insulate the diaphragm pot 130. No acoustic bridges, i.e. sound-transmitting connections, exist between the diaphragm pot 130 and the printed circuit board 120 or between the diaphragm pot 130 and the housing 170. The contact carrier is rigidly connected to the printed circuit board; this connection includes, in particular, electrical connections.
Electrical connections between the printed circuit board and the piezoelectric element 110 are acoustically insulating and include, in articu1ar, litz wire.
Connections of such a type are, in particular, the leads 140, 140' and 142, which have been formed in acoustically insulating manner.
Starting from the leads 140, 142 and the contact elements 182, 180 of the contact carrier 190 it is evident that the contact points 184, 186 may also be situated outside the diaphragm pot 130 without a high susceptibility to interference arising. This is obtained by a spacing existing between the leads 140, 142 and between the contact elements 180, 182 that is as small as possible, i.e. a spacing that corresponds substantially to the electrode-gap width 116, inclusive of an additional contact-point width which, for example, corresponds to the width of the contact points 150, 152. The contact carrier 190 may further exhibit fastening elements which connect the contact carrier 190 to the housing 170.
Lastly, the housing 70 or 170 may exhibit,' on an inside of the housing, fastening elements with which the printed circuit board 20 or 120 is connected to the housing 70 or 170, respectively.
The contact elements 180, 182 represented in Figure 2 may be, in particular, contact bushes, into which the associated ends of the leads 140, 142 extend. The contact between the leads 140, 142 and the contact elements 180, 182 is provided by a press fit or a crimp connection, by the contact elements 180, 182, implemented as contact bushes, being crimped. Alternatively, the contact variants described above are possible, i.e. therruocompression contacts, solder contacts or other material-closure contacts, in particular resistance-welding contacts, in order to connect the ends of the leads 140, 142 facing away from the piezoelectric element to the contact elements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1616926.0A GB2541560B (en) | 2011-06-15 | 2012-06-14 | Ultrasonic transducer with piezoelectric element and distance sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102011077553A DE102011077553A1 (en) | 2011-06-15 | 2011-06-15 | Ultrasonic transducer with piezo element and distance sensor |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB201210631D0 GB201210631D0 (en) | 2012-08-01 |
| GB2491977A true GB2491977A (en) | 2012-12-19 |
| GB2491977B GB2491977B (en) | 2017-06-07 |
Family
ID=46640972
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1616926.0A Active GB2541560B (en) | 2011-06-15 | 2012-06-14 | Ultrasonic transducer with piezoelectric element and distance sensor |
| GB1210631.6A Active GB2491977B (en) | 2011-06-15 | 2012-06-14 | Ultrasonic transducer with piezoelectronic element and distance sensor |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1616926.0A Active GB2541560B (en) | 2011-06-15 | 2012-06-14 | Ultrasonic transducer with piezoelectric element and distance sensor |
Country Status (5)
| Country | Link |
|---|---|
| CN (1) | CN102833658B (en) |
| DE (1) | DE102011077553A1 (en) |
| FR (1) | FR2976758B1 (en) |
| GB (2) | GB2541560B (en) |
| IT (1) | ITMI20120927A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2879128A1 (en) * | 2013-11-27 | 2015-06-03 | Valeo Interior Controls (Shenzhen) Co., Ltd | Ultrasonic sensor and method of manufacturing same |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102013211596A1 (en) | 2013-06-20 | 2014-12-24 | Robert Bosch Gmbh | Method for electrically contacting a piezoceramic |
| DE102015209238A1 (en) * | 2015-05-20 | 2016-11-24 | Robert Bosch Gmbh | Acoustic sensor for sending and receiving acoustic signals |
| DE102016120120A1 (en) * | 2016-10-21 | 2018-04-26 | Valeo Schalter Und Sensoren Gmbh | Sensor device for a motor vehicle with a arranged on a membrane damping element, arrangement, driver assistance system and motor vehicle |
| DE102016221535A1 (en) * | 2016-11-03 | 2018-05-03 | Robert Bosch Gmbh | ultrasound transducer |
| DE102017109159B4 (en) * | 2017-04-28 | 2019-02-14 | Valeo Schalter Und Sensoren Gmbh | Ultrasonic transducer device and contacting method |
| DE102019111741A1 (en) * | 2019-05-07 | 2020-11-12 | Valeo Schalter Und Sensoren Gmbh | Contacting method and ultrasonic transducer device |
| DE102021104697A1 (en) | 2021-02-26 | 2022-09-01 | Tdk Electronics Ag | ultrasonic transducer |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62294921A (en) * | 1986-06-14 | 1987-12-22 | Omron Tateisi Electronics Co | Ultrasonic wave detector |
| US20030121331A1 (en) * | 2001-12-27 | 2003-07-03 | Hideo Mitsuoka | Ultrasonic transceiver and ultrasonic clearance sonar using the same |
| JP2006254360A (en) * | 2005-03-14 | 2006-09-21 | Mitsumi Electric Co Ltd | Apparatus for transmitting/receiving ultrasonic wave |
| US20070115102A1 (en) * | 2005-11-21 | 2007-05-24 | Denso Corporation | Ultrasound sensor |
| US20070157728A1 (en) * | 2006-01-06 | 2007-07-12 | Denso Corporation | Ultrasonic sensor transmitting and receiving ultrasonic frequencies adjusted according to temperature |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4329055A1 (en) * | 1993-08-28 | 1995-03-02 | Teves Gmbh Alfred | Pressure-tight converter for motor vehicles |
| DE19835782A1 (en) * | 1997-08-23 | 1999-04-01 | Itt Mfg Enterprises Inc | Ultrasonic transducer with a circuit board arranged in the longitudinal direction of the transducer for an electrical circuit |
| JP2001128293A (en) * | 1999-10-28 | 2001-05-11 | Murata Mfg Co Ltd | Piezoelectric device |
| EP1315145A1 (en) * | 2001-11-22 | 2003-05-28 | HERA Rotterdam B.V. | Housing for an ultrasonic transducer |
| DE102005045019A1 (en) * | 2005-09-21 | 2007-03-22 | Robert Bosch Gmbh | ultrasonic sensor |
| JP2010118958A (en) * | 2008-11-13 | 2010-05-27 | Nippon Ceramic Co Ltd | Ultrasonic transducer |
-
2011
- 2011-06-15 DE DE102011077553A patent/DE102011077553A1/en active Pending
-
2012
- 2012-05-29 IT IT000927A patent/ITMI20120927A1/en unknown
- 2012-06-13 FR FR1255515A patent/FR2976758B1/en active Active
- 2012-06-14 GB GB1616926.0A patent/GB2541560B/en active Active
- 2012-06-14 GB GB1210631.6A patent/GB2491977B/en active Active
- 2012-06-14 CN CN201210196907.0A patent/CN102833658B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62294921A (en) * | 1986-06-14 | 1987-12-22 | Omron Tateisi Electronics Co | Ultrasonic wave detector |
| US20030121331A1 (en) * | 2001-12-27 | 2003-07-03 | Hideo Mitsuoka | Ultrasonic transceiver and ultrasonic clearance sonar using the same |
| JP2006254360A (en) * | 2005-03-14 | 2006-09-21 | Mitsumi Electric Co Ltd | Apparatus for transmitting/receiving ultrasonic wave |
| US20070115102A1 (en) * | 2005-11-21 | 2007-05-24 | Denso Corporation | Ultrasound sensor |
| US20070157728A1 (en) * | 2006-01-06 | 2007-07-12 | Denso Corporation | Ultrasonic sensor transmitting and receiving ultrasonic frequencies adjusted according to temperature |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2879128A1 (en) * | 2013-11-27 | 2015-06-03 | Valeo Interior Controls (Shenzhen) Co., Ltd | Ultrasonic sensor and method of manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2491977B (en) | 2017-06-07 |
| FR2976758B1 (en) | 2018-03-02 |
| DE102011077553A1 (en) | 2012-12-20 |
| CN102833658A (en) | 2012-12-19 |
| CN102833658B (en) | 2018-03-30 |
| GB2541560B (en) | 2017-08-16 |
| GB201210631D0 (en) | 2012-08-01 |
| FR2976758A1 (en) | 2012-12-21 |
| ITMI20120927A1 (en) | 2012-12-16 |
| GB2541560A (en) | 2017-02-22 |
| GB201616926D0 (en) | 2016-11-16 |
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