WO1990002346A1 - Transducteur ultrasonique et procede - Google Patents

Transducteur ultrasonique et procede Download PDF

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Publication number
WO1990002346A1
WO1990002346A1 PCT/US1988/002785 US8802785W WO9002346A1 WO 1990002346 A1 WO1990002346 A1 WO 1990002346A1 US 8802785 W US8802785 W US 8802785W WO 9002346 A1 WO9002346 A1 WO 9002346A1
Authority
WO
WIPO (PCT)
Prior art keywords
transducer
foil
piston
distance
echo
Prior art date
Application number
PCT/US1988/002785
Other languages
English (en)
Inventor
James N. Kniest
James M. Hossack
Walter Lecoque
Original Assignee
Ultrasonic Arrays, Inc.
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
Priority to US06/828,924 priority Critical patent/US4769793A/en
Application filed by Ultrasonic Arrays, Inc. filed Critical Ultrasonic Arrays, Inc.
Priority to JP63507299A priority patent/JP2755405B2/ja
Priority to PCT/US1988/002785 priority patent/WO1990002346A1/fr
Publication of WO1990002346A1 publication Critical patent/WO1990002346A1/fr

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
    • G01S7/523—Details of pulse systems
    • G01S7/526—Receivers
    • G01S7/529—Gain of receiver varied automatically during pulse-recurrence period
    • 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
    • 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
    • G01S7/52004—Means for monitoring or calibrating
    • G01S7/52006—Means for monitoring or calibrating with provision for compensating the effects of temperature
    • 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

Definitions

  • This invention relates to an ultrasonic transducer and method.
  • Another object of the invention is to provide a transducer of the above character which is very durable and can be utilized in adverse environments.
  • Another object of the invention is to provide a trans ⁇ ducer of the above character in which it makes it possi ⁇ ble to make measurements which are independent of changes of the speed of travel of sound in air and thus indepen ⁇ dent of temperature.
  • Another object of the invention is to provide an apparatus and method of the above character in which measurements can be made independent of temperature and independent of the position of the exact position of the foil from the reference surface. Additional objects and features of the invention will appear from the following description in which the pre ⁇ ferred embodiments are set forth in detail in conjuncr tion with the accompanying drawings:
  • Fig. 1 is an isometric view of a transducer incorporating the present invention.
  • Fig. 2 is an exploded view of the transducer shown in Fig. 1.
  • Fig. 3 is an isometric, view of another embodiment of a fronthousing for use on the transducer shown in Fig. 1 showing the use of two separate reference surfaces car ⁇ ried by a single reference bar.
  • Fig. 4 is an isometric view of still another front hous ⁇ ing showing the use of two separate reference bars car ⁇ rying two separate reference surfaces.
  • Fig. 5 is an isometric view of still another embodiment of a front housing showing the use of two reference bars providing two reference surfaces in which the reference bars are disposed at an angle to each other.
  • Fig. 6 is a block diagram illustrating the timing tech ⁇ nique to estimate target distance.
  • Fig. 7 is a waveform of typical echo pulse and also a transmit pulse.
  • Fig. 8 is a block diagram of a circuit to process an echo pulse.
  • Fig. 9 is a circuit schematic partially in block diagram form illustrating in detail a pulse circuit for the pro ⁇ duction of ultrasonic energy.
  • Fig. 10 is a block diagram of the overall pulse produc ⁇ tion and echo receive system including a gain compensa ⁇ tion circuit.
  • Fig. 11 is a cross-sectional view and an alternative embo- ment of an ultrasonic transducer embodying the present invention.
  • Fig. 12 is an enlarged view of a portion of Fig. 11.
  • Fig. 13 is a detailed circuit schematic of a portion of Fig. 11.
  • Figs. 14A and 14B are cross-sectional elevation views of portions of Fig. 12 showing a processing step in forming that portion, and Fig. 14B also includes a block diagram of an alternative embodiment of the invention.
  • Fig. 15A is a line view in elevation of an alternative embodiment of the present invention.
  • Fig. 15C is a plan view in an unfolded form of a portion of Fig. 15A.
  • Fig. 16 is a diagramatic sketch of Fig. 11 showing one embodiment of its use.
  • Fig. 17 is a diagramatic sketch of Fig. 11 showing another embodiment of its use.
  • the ultrasonic transducer and method of the present inven ⁇ tion is used in an apparatus for detecting the distance to an object using ultrasonic energy.
  • the transducer which includes a foil creates ultrasonic energy. It also in ⁇ cludes a reference having a surface for reflecting ultra ⁇ sonic energy to create an echo. The reference is posi ⁇ tioned between the transducer and the object with the re- ference being at a known distance from the transducer.
  • the apparatus includes means for ascertaining the dis ⁇ tance to the target by taking a ratio of the time required for ultrasonic energy to travel from the foil to the re ⁇ ference surface and an echo to return from the reference surface and for ultrasonic energy ' to travel from the foil to the object and an echo to return from the object so that the distance to the object can be ascertained inde ⁇ pendent of temperature of the air through which the ultra ⁇ sonic energy travels.
  • a second reference surface is provided which is spaced a predetermined distance away from the first re ⁇ ference surface and which is disposed between the trans ⁇ ducer and the object.
  • the apparatus also includes means for ascertaining the elapsed times between the echoes re ⁇ ceived from the first named and additional reference sur ⁇ faces for ascertaining the distance to the object inde ⁇ pendent of the exact position of the foil in the trans ⁇ ducer.
  • the ultrasonic transducer 11 which is shown in Figs. 1 and 2 of the drawings consists of a mounting stud 12 and a front housing 13.
  • the mounting stud 12 is provided with an intermediate cylindrical portion 16 and an end cylin ⁇ drical portion 17.
  • the mounting stud 12 can be formed of a suitable material such as aluminum.
  • the mounting stud 12 is provided with a cylindrical bore 18 which extends longitudinally of the same.
  • the portion of the bore which is in the end portion 17 is provided with interior threads 19 of a standard type so that the mounting stud can be threaded onto a conventional piece of one-half inch elec ⁇ trical conduit (not shown) .
  • the intermediate cylindrical portion 16 is provided with exterior threads 21 also of a conventional type to facilitate mounting of the transducer 11 on apparatus such as on a panel (not shown) .
  • the mounting stud 12 is also provided with an annular re ⁇ cess 22 which is immediately behind a radially extending flange 23.
  • the recess 22 can be omitted if desired and is merely provided to clear the tool when machining the mounting stud 12.
  • the mounting stud 12 is also provided with a front cylindrical portion
  • a coaxial cable 31 is provided which is connected to the transducer 11. It consists of an outer cylindrical ground 32 and a center conductor 33.
  • the outer conductor 32 is connected by a lead 36 to a stud 37 by suitable means such as brazing.
  • the stud 37 is carried by a ground ⁇ ing disc 38 formed of a suitable material, such as brass.
  • the grounding disc 38 is secured to the front surface of the cylindrical portion 34 by fillister head screws 39 extending through holes 40 provided in the grounding disc 38 and threaded into threaded holes 41 provided in the cylindrical portion 24.
  • the grounding disc 38 is provided with a centrally dis ⁇ posed hole 42 through which the center conductor 33 of the coaxial cable 31 extends.
  • the center conductor 33 also extends through another hold 43 provided in a piston mount ⁇ ing disc 44.
  • the piston mounting disc 44 supports a piston 46 which is disc-like in shape and which is provided with a centrally disposed rearwardly extending stud 47 which seats within the hole 43 of the piston mounting disc 44.
  • the center conductor 33 of the coaxial cable 31 is secured to the stud 47 by suitable means as, for example, by the use of an L-shaped spade lug 48 by suitable means, such as solder.
  • the lug 48 is secured to the stud 47 by a screw 49 threaded into the stud.
  • the front side of the piston 46 is provided with a flat planar circular surface 50 which serves as one plate of a capacitor for the transducer 11.
  • the piston mounting plate 44 is provided with four slots 51 on the outer margin of the same which are adapted to accommodate the heads of the fillister head screws 39. It also is pro ⁇ vided with four holes 52 for receiving four fillister screws 53 which are used for securing the front housing 13 to the mounting stud 12.
  • a support ring 56 is pro ⁇ vided which has a central opening 57 which accommodates the piston 46.
  • the support ring 56 is seated upon the piston mounting disc 44 and is provided with four uniform ⁇ ly spaced holes 58 which are adapted to accommodate the screws 53.
  • the support ring 56 can be formed of any suit ⁇ able material Although it need not be conducting, it has been formed of aluminum to provide the desired support.
  • a foil 61 is provided which has its outer margin secured to the support ring 56 by suitable means, such as double- sided adhesive tape (not shown) .
  • the foil 61 is formed of a layer of insulating material and a conducting layer 63 formed on the surface of the insulating material facing forwardly.
  • the layer of the insulating material can be of any suitable type as, for example, a film of Kapton of a suitable thickness as, for example, 30 gauge Kapton having a thickness of approximately .3 of a mil.
  • the con ⁇ ducting layer 63 is formed of a suitable material, such as gold evaporated onto the front surface of the insulat ⁇ ing layer to a suitable thickness as, for example, 50 to 500 Angstroms.
  • the conducting layer 63 formed on the insulating layer 62 of the foil 61 serves as the second plate of a capacitor for the transducer 11.
  • the piston 46 is secured to the piston mounting disc 44 by suitable means, such as an adhesive.
  • suitable means such as an adhesive.
  • Eastman 910 super glue can be utilized if desired.
  • the piston mounting disc 44 can be se ⁇ cured to the grounding disc 38 by an adhesive.
  • the co ⁇ axial cable 31 is extended through the mounting stud 12 and is secured to the lug 48 by soldering.
  • the grounding disc 38 is then secured to the " mounting stud 12 by the use of the fillister head screws 39 extending through the slots 51 of the piston mounting disc 44.
  • the foil can be secured to the support ring 56 by the double- sided sticky tape and then the support ring 56 can be placed over the piston 46.
  • the housing 13 is provided with two upstanding posts 71 formed integral therewith and which extend forwardly from the front housing 13.
  • the posts 71 carry a reference bar 72.
  • the reference bar 72 is roughly rectangular in cross- section and is provided with first and second surfaces 73 and 74 which are parallel to each other and lie in planes which are generally parallel to the plane of the foil 61.
  • the reference bar 72 is positioned in such a manner so that the first surface 73 is within one-half inch to an inch of the foil 61.
  • the reference bar has been shown as being rectangular in cross section, this need not necessarily be the case. For example, it can be in the form of a small rod or a wire if desired.
  • the reference bar or member 72 be of rela ⁇ tively small dimensions in thickness so that it does not unduly obstruct the ultrasonic energy being emitted from the transducer.
  • the reference bar should be strong so that it will not bend under normal usage of the transducer However, it should not be so large as to unduly obstruct the sound produced by the transducer from reaching the target.
  • the surface 73 is planar and lies in a plane which is parallel to the foil 61.
  • the other surface 74 since it is de ⁇ sired only to receive one reflection from the reference bar 72 is rounded or in other words is substantially con ⁇ vex on its outer or forward surface so that the sound wave propagated by the transducer will roll around the surface and will not be reflected by that surface.
  • FIG. 3 there is shown another embodiment of a front housing 76 having upstanding posts 77 carrying a referenc bar 78 that is provided with first and second reference surfaces 79 and 81 in which both of the reference surface 79 and 81 are planar and parallel to the foil 61 so as ' to provide reference echoes from both the surfaces 79 and 81.
  • Fig. 4 there is shown still another embodiment of a front housing 84 which is provided with upstanding posts 86 carrying two reference bars 87 and 88 which are in general alignment with each other but superposed one above the other and spaced apart from each other.
  • the reference bar 87 is provided with a planar surface 89 . which is parallel to the foil 61 and a curved surface 91 which is curved so as not to provide a reflection.
  • the reference bar 88 is provided with a planar sur ⁇ face 92 parallel to the foil 61 and also parallel to the surface 89.
  • the surface 93 is rounded so as not to provid an echo.
  • Fig. 5 there is provided still another embodiment of a front housing.
  • the front housing 96 is provided with two pairs of upstanding posts 97 and 98 with post 97 carrying one reference bar 99 and the other post 98 carrying another reference bar 101.
  • the reference bar 99 is provided with a surface 101 which is planar and parallel to the foil 61. It is also provided with a sur ⁇ face 103 which is rounded to inhibit echoes from that sur ⁇ face.
  • the bar 101 is provided with a planar surface 104 parallel to the foil 61. It is also provided with a sur ⁇ face 106 which is rounded to inhibit echoes.
  • the reference bar can be disposed at any angle with respect to the foil 61 and still accomplish the desired purpose.
  • the surfaces 102 and 104 be spaced at different dis ⁇ tances from the foil. It also should be appreciated that, if desired, the reference bars can be supported in any suitable manner from the front housing. For example, in ⁇ stead of separate posts, a single set of posts can be pro ⁇ vided supporting a ring in which the reference bars can be inserted as cross members.
  • transducer 11 Operation and use of the transducer 11 hereinbefore de ⁇ scribed may now be briefly described, as follows: Let it be assumed that it is desired to utilize the trans ⁇ ducer 11 in a system and apparatus of a suitable type as, for example, of the type disclosed in application. Serial No. 532,575, filed on September 15, 1983 and entitled "ULTRASONIC APPARATUS, SYSTEM AND METHOD.”
  • the trans ⁇ ducer 11 When the trans ⁇ ducer 11 is supplied with electrical energy of a suitable frequency as, for example, from 100 to 500 kilohertz and preferably in a range of 250 kilohertz it will produce ultrasonic energy at that frequency.
  • the application of such energy to the transducer will cause the " foil 61 to move very ra ⁇ pidly to cause it to move air to propagate sound energy.
  • the ultrasonic energy passes from the transducer, it impinges upon the surface 73 of the reference bar 72.
  • the surface 73 of the reference bar 72 is a known distance away from the foil 61.
  • Two timers are utilized in this embodiment of the system. One of the timers is utilized for determining the time it takes the sound energy to leave the transducer and to echo from the reference surface 73. The other timer is utilized to calculate the time it takes the sound energy to leave the transducer and to echo from the target.
  • the reference bar 72 is of a size so that it will not block most of the sound energy leaving the transducer so that sound energy will reach the target as well as the reference bar.
  • the computer which is provided in the system is then utilized to calculate the exact distance to the target utilizing the two times of the ultrasonic energy to echo from the surface 73 and to echo from the target.
  • the computer which is provided in the system is then utilized to calculate the exact distance to the target utilizing the two times of the ultrasonic energy to echo from the surface 73 and to echo from the target.
  • FIG. 3 Such an arrangement is shown in Figure 3 in which two reference surfaces are provided, namely, surfaces 79 and 81, both of which are planar and parallel to the foil 71 with the two reference surfaces 79 and 81 being spaced a known distance apart.
  • the three timers utilized in the system are started at the time the sound energy leaves the foil with the first timer measuring the time for the echo to return from the surface 79, the second timer measuring the time it takes for the sound to travel from the foil 61 and the echo to return from the second surface 81 and the third timer measuring the time it takes for sound to travel from the foil 61 to the target and its echo to return from the target.
  • the computer in the system takes the time recorded by the first timer and subtracts it from the time for the second timer. This difference is then utilized for calculating the actual distance to the target as was done with a sample reference, except that a sealer value is used to compensate for the differential measurement made for the time of travel between the foil and the first and second reference surfaces.
  • a sealer value is used to compensate for the differential measurement made for the time of travel between the foil and the first and second reference surfaces.
  • a further embodiment is using the inner reference bar's echo to start two timers. One timer for the target, the other for the second reference echo. This way one set of timers is eliminated.
  • Figure 6 illustrates .the foregoing technique of computing the distance to target independent of temperature variations and includes a target counter 110, a counter 111 responsive to a first reference surface, and a counter 112 responsive to a second reference surface.
  • this counter is optional or may be eliminated if only one reference is desired.
  • the counter start input at 114 is driven by the transmitted transducer pulse 116 and specifically where the pulse has its first negative excursion or dip 117.
  • a stop input at 118 is provided for each of the counters and at an exact phase point of a received echo, as will be discussed in conjunction with Figures 7 and 8.
  • an associated microprocessor ( Figure 10) is utilized to determine which is the transmitted pulse which is followed by a first reference echo, a second reference echo and a target echo.
  • the ratio of the echo and reference echo is taken and multiplied by the known distance to the reference ban, assuming only the reference #1, counter 111 is utilized. Since the reference bar must be a known distance the preferred technique in accordance with the invention is to construct a specific apparatus, measure this distance, and then assign a particular calibration number to that transducer apparatus. This is indicated by the factory transducer calibration input 121. This technique eliminates manufacturing to close tolerances in that the reference bar does not have to be placed at an exact known distance.
  • Figure 7 illustrates the waveform of a typical received echo signal from the reference on target.
  • the technique used in the present invention is that the echo signal must pass positively above a threshhold and then the stop signal is provided at the next zero crossing.
  • a threshhold is indicated at 123 of approximately 400 millivolts.
  • the stop occurs at the zero crossing at 124, and is so labeled.
  • the start signal occurs at the first dip and is also labeled.
  • the timing is very precise, since the time duration from start to stop is four microseconds. Other alternatives are of course available such as utilizing the second zero crossing.
  • a comparator with a large hysteresis is utilized as illustrated in Figure 8.
  • the threshhold of the comparator is indicated as 400 millivolts (which is an arbitrary number ⁇ .
  • the use of the large hysteresis provides for a stop signal to occur at the first zero crossing after the threshhold is reached. Thus, this provides the stop signal for both the target and reference counters 110, 111, and 112.
  • a pulse generating circuit which avoids inductive components (that is, is inductorle ⁇ s) is utilized as indicated in Figure 9. This is as opposed to pulse transformers which have been utilized.
  • a fixed high voltage supply 126 of for example 300 volts D.C. is connected to the transducers 31 solely by means of a resistor 127.
  • the transducer is an effective- capacitor. Therefore, in operation -the capacitor is charged through resistor 127.
  • a voltage field effect transistor switch 128 is triggered by a control pulse from the transmitter receive switch 33. All of the stored energy contained in the capacitor of transducer 31 is rapidly converted to ultrasonic energy. Thus, the echo signal will be a precise waveform which is suitable for accurate analysis of the type shown in Figure 7.
  • a specific receive circuit on line 129 includes a D.C. blocking capacitor 131, a current limiting resistor 132 and a pair of blocking diodes 133.
  • the resistor 127 acts as both a charging resistor and after the sudden discharge as a damper to quiet the ringdown oscillations.
  • Transducer 31 is connected to a receive circuit including a voltage controlled receiver/amplifier 134 whose output is either routed directly to a voltage to digital converter 136 whose information is then processed by a microprocessor in addition to controlling other facets of the process (such as selecting reference echoes) drives a digital word to voltage converter 138 which is connected to amplifier 134 to change its gain.
  • microprocessor 137 of course controls the transmit circuit 139 as for example illustrated in Figure 9. This would be part of the transmit receive switch 33.
  • the transducer 31 is first fired by the transmit circuit 139 to produce an ultrasonic pulse.
  • Microprocessor 137 engages the receiver to listen for echo signals from either one or both references and the target.
  • the peak voltage detector 138 is inserted in the circuit by the microprocessor 137 and the peak voltage of a reference echo is converted to a digital number by converter 136. If this is less than a preset value, it indicates the transducer is too weak, and thus the gain of the receiver/amplifier 134 is increased by the microprocessor 137. Thus, in effect, a feedback process is implemented.
  • Fig. 11 is similar to that of Figs. 1 and 2, in that the ultrasonic transducer includes a cylindrical mounting stud 12" with a co-axial cable 31' and a front cylindrical housing 13' with legs 71' carrying an appropriate reference bar.
  • Housing 13* which is composed of, for example, aluminum which has been anodized is fastened to mounting stud 12' and encloses the transducer assembly which includes a piston 140 and an associated foil 141.
  • Piston 140 which is composed of aluminum includes a stud portion 142 and is generally retained by a plastic disc 143 having a re ⁇ cess 144 in its top surface. This is shown in Fig. 12. Referring briefly to Figs. 14A and 14B, the surface of the mounting disc 143a is made flush with the surface of 140a of the piston 140 by the process as illustrated in Fig. 14A of first gluing the piston 140 in the recess 144.
  • the foil is composed of a Mylar or Kapton insulating layer 147 which has evaporated on it a very thin layer of gold 148.
  • a non-con ⁇ ductive protective layer such as silicone based plastic 149 which typically is vapor deposited.
  • a suitable mater ⁇ ial is Parylene.
  • the ultrasonic transducer When the ultrasonic transducer is used in severe ambient condition, it protects the very thin gold layer from chemicals and abrasives. This is neces ⁇ sary, for example since the gold may be only 300 angstroms thick.
  • the Parylene layer may be approximately 2 micro ⁇ meters. Because the thinness of the Paralene, it does not affect the production of the beam of ultrasonic energy whic is transmitted from the surface of the foil.
  • annular ring 151 of, for example, silver paint is coated on the gold surface 148 to provide for more effective conductive contact with the hous ⁇ ing 13' as illustrated in Fig. 11. More specifically this contact is the effective ground for the foil and is implemented by the fact of the retaining screws 152 holding the housing 13' to the mounting stud 12' , Also contact occurs between the housing and mounting stud at the interface 153.
  • the mounting stud is, in essence, the ground connection and as indi ⁇ cated at the terminal 154 is connected to the ground of the co-axial cable 31".
  • the co-axial cable 31' with its outer cable as ground as shown in 154 pro ⁇ vides on its inner cable 156 an appropriate alternat ⁇ ing voltage for producing the ultrasonic beam.
  • this is an appropriate electrical voltage in which line 156 is connected to the aluminum piston 140 with the foil 141 being grounded thereto by forming an effective capacitor.
  • a bypass leak ⁇ age resistor 157 with a relatively high resistance, for example 10 megohms, provided between line 156 and ground. This resistance is contained in the shroud 157, as illu ⁇ strated in Fig. 11.
  • the center cable 156 is connected to the stud 142 of piston 140.
  • the foil 141 is fixed only to the plastic mounting disc 143 so that it can freely vibrate or freely move with respect to piston 140.
  • serial No. 532,576 filed September 15, 1983 entitled "ULSONIC APPARATUS SYSTEM AND METHOD" and assigned to the present assignee
  • the surface 140a of the piston 140 which interfaces with the foil is treated to enhance the production of ultra ⁇ sonic energy.
  • a substantial portion of th foil 141 is exposed because of the cylindrical nature of housing 13' to allow the production of an ultrasonic beam approximately along the nominal axis 161.
  • an air passage way 162 is provided in the stud 142 of the piston 140 by means of a hole 163 drilled through the centerline of the piston. Then screw 164 is placed in hole 163 which again is drilled in the center to provide the passage 162.
  • a resilient bag or balloon 166 As illustrated in Fig. 11, in one embodiment attached - to this air passage is a resilient bag or balloon 166. Toy balloon is contained in a plastic tube 167 which holds it on the coupling 168 which in turn is attached to the smaller diameter rubber tube 169 which is affixed to the end of screw 164. Thus, this provides for full containment of the atmosphere.
  • the coaxial signal cable 171 itself can be used which has an air pas ⁇ sage 172 in it.
  • the air can be expelled to the ambient air or alternatively a resilient bag 166 can still be employed within.
  • the special coaxial cable 171 which, of course, also includes the appropriate electrical connections to drive the transducer may be of a type sold under the trademark "HELI-AX.” This is a spirally wrapped coaxial cable.
  • a covering material in the form of a cone 173 is placed over the housing 13' and the re ⁇ ference bar legs 71'.
  • This material is made typically of a polyester cloth which has a weave which is tight enough to eliminate dust but yet allow effective transmission without undue attenuation of ultrasonic energy.
  • Fig. 15C illustrates the cloth as it is cut initially and then when it is folded at the line 174 and placed over housing 13', the edges of the cloth are seared or fused together at 176 and 177, as illustrated in Fig. 15B to provide a tight fit.
  • a plate 179 is provided which is at a predetermined distance of the foil of the trans ⁇ ducer and which includes an aperture 181 with the center of the aperture on the nominal beam axis 161. This pro ⁇ vides a smaller sensing beam 182 and allows the beam to be reflected back to the transducer. At the same time angling the plate 179 at an acute angle to axis 161, the the beam is deflected at 183-to prevent unwanted reflec ⁇ tions.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)

Abstract

Est décrite une sonde (11) pour mesurer avec précision la distance d'un objet au moyen d'énergie acoustique. Un transducteur ultrasonique (50) génère un signal ultrasonique en réponse à un stimulus électrique. La sonde comporte une paire de surfaces de référence espacées placées entre le transducteur (50) et l'objet afin de réfléchir l'énergie ultrasonique pour créer un écho. Les surfaces de référence sont espacées d'une distance connue. Un moyen est prévu pour déterminer la distance de l'objet en établissant un rapport du temps nécessaire à l'écho venant d'une des surfaces de référence pour revenir à l'armature (61) et du temps nécessaire à un écho pour revenir de l'objet cible, afin que les distances puissent être déterminées avec précision indépendamment de la température et d'autres conditions ambiantes qui mesurent le temps de trajet. En outre, les moyens de mesure déterminent le temps écoulé entre la réception des première et seconde surfaces de référence afin de déterminer avec précision la distance indépendamment de légères variations de la position de l'armature (61) du transducteur.
PCT/US1988/002785 1985-07-24 1988-08-23 Transducteur ultrasonique et procede WO1990002346A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US06/828,924 US4769793A (en) 1985-07-24 1986-02-12 Dual reference surface transducer
JP63507299A JP2755405B2 (ja) 1988-08-23 1988-08-23 超音波エネルギーを利用して対象までの距離を測定する装置
PCT/US1988/002785 WO1990002346A1 (fr) 1988-08-23 1988-08-23 Transducteur ultrasonique et procede

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1988/002785 WO1990002346A1 (fr) 1988-08-23 1988-08-23 Transducteur ultrasonique et procede

Publications (1)

Publication Number Publication Date
WO1990002346A1 true WO1990002346A1 (fr) 1990-03-08

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PCT/US1988/002785 WO1990002346A1 (fr) 1985-07-24 1988-08-23 Transducteur ultrasonique et procede

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JP (1) JP2755405B2 (fr)
WO (1) WO1990002346A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
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CN102798671A (zh) * 2011-03-28 2012-11-28 丰田自动车株式会社 超声波测量方法和超声波测量系统

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JP2006003124A (ja) * 2004-06-15 2006-01-05 Nippon Soken Inc 超音波センサ装置
KR101143381B1 (ko) * 2009-11-27 2012-05-22 주식회사 나인티시스템 초음파 거리측정의 환경소음 구분방법
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CN102798671A (zh) * 2011-03-28 2012-11-28 丰田自动车株式会社 超声波测量方法和超声波测量系统

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JP2755405B2 (ja) 1998-05-20

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