US3735292A - Ultrasonic delay line having offset boundary surfaces at point where beam strikes surface - Google Patents

Ultrasonic delay line having offset boundary surfaces at point where beam strikes surface Download PDF

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Publication number
US3735292A
US3735292A US00175203A US3735292DA US3735292A US 3735292 A US3735292 A US 3735292A US 00175203 A US00175203 A US 00175203A US 3735292D A US3735292D A US 3735292DA US 3735292 A US3735292 A US 3735292A
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Prior art keywords
ultrasonic
offset
delay line
ultrasonic wave
transducer
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Expired - Lifetime
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US00175203A
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English (en)
Inventor
H Probst
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Licentia Patent Verwaltungs GmbH
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Licentia Patent Verwaltungs GmbH
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/30—Time-delay networks
    • H03H9/36—Time-delay networks with non-adjustable delay time

Definitions

  • a delay member in which'the path of travel of an ultrasonic wave beam from an input transducer to an [22] filed 1971 output transducer associated with the member is 211 App], 175,203 lengthened by reflection of the beam from at least one of the planar boundary surfaces of the member. At least one of these surfaces is divided into at least two [30] Foreign Apphcmon Data substantially parallel, but offset, surfaces so that 21 Aug. 28, 1970 Germany ..P 20 42 865.3 wave beam from the input transducer impinging On these offset surfaces is separated into at least two 52 us. 01. ..333/30 R 333/71 Wave beam which travel Paths diffeem [51] Int CL; 6 9/30 lengths to the output transducer.
  • At least one of the [58] Field 0 R 71 72 separate beams is effective, at certain frequencies, to produce a counter voltage at the output transducer to attenuate, to the desired degree, the voltage [56] References Clted developed at the output transducer and improve the UNITED STATES PATENTS transmission characteristic of the delay line.
  • the present invention relates to an ultrasonic delay line in which an ultrasonic beam transmitted through a delay member, from an electromechanical input transducer to an electromechanical output transducer, is reflected, at least once, at the planar boundary surfaces of the delay member.
  • Ultrasonic delay lines in which the path of travel of ultrasonic wave beams can be extended by deflecting or reflecting the beams in a delay member are known. With such a system multiple reflection of the beam permits the spatial dimensions of the delay member to be smaller.
  • the transmission characteristic of a delay line is generally similar to a bell-shaped curve, i.e. a signal of a limited bandwidth can be transmitted by such a delay line.
  • this curve representing output voltage as plotted against frequency, has an asymmetric shape, caused by inaccuracies in the shape of the delay member or because of frequency dependent attenuation of the ultrasonic beam.
  • PAL phase alternating line
  • a delay member has a plurality of beam reflection surfaces at least one of which is divided into two, or more, substantially parallel, offset, partial reflection surfaces.
  • the difference in the length of the path between the two partial beams of ultrasonic energy and the ratio of the width of the two partial beam is so selected that the transmission characteristic in the passband is flattened.
  • FIG. I is a front elevation view of a delay member, constituting a preferred embodiment of the invention.
  • FIG. 1a is a side elevation view of the delay member shown in FIG. 1.
  • FIG. 2 is an enlarged detail view of an offset portion of the reflection surface formed in the delay member shown in FIG. 1 and 2.
  • FIG. 3 is a diagram depicting the transmission characteristic of a delay member.
  • FIG. 3a is a diagram of the counter voltage produced by a member according to the invention, to shift the output voltage values in a direction to produce the desired characteristic of FIG. 3.
  • FIG. 4 is a view similar to FIG. 3 showing different transmission characteristic curves.
  • FIG. 4a is a view similar to FIG. 3a showing a different counter voltage which is produced to shift the output voltage values in the direction of the desired characteristic of FIG. 4.
  • FIG. 1 shows a delay member, of a material such as glass, providing an ultrasonic delay line resulting from a five-fold reflection of the ultrasonic beam.
  • the ultrasonic energy is transmitted from an input piezoelectric transducer 2 to an output piezoelectric transducer 3 in the form of a beam, generally indicated at 4.
  • the five reflection surfaces are a, b,-b c, d and e.
  • At least one of these reflection surfaces is divided into for example, two parallel offset partial reflection surfaces b and 12 as seen in FIGS. 1 and 2, in order to produce two resulting ultrasonic wave beams 5 and 6 that will have the different lengths of paths in the delay member 1.
  • FIG. 2 shows to an enlarged scale, the reflection surface (b, and b as divided into the two steep reflection surfaces b and b
  • the two steep reflection surfaces b and b are parallel to one another and offset normal to their planes by a distance h.
  • the impinging ultrasonic wave beam 4 is divided into two beam portions generally indicated at 5 and 6.
  • the selection of the location and size of the step or offset between the two partial reflection surfaces b and [1 determines the ratio of the widths i and g of the two beam portions 5 and 6.
  • the degree of correction can be adjusted and, predominantly by the selected difference in path length, the frequency range in which the transmission characteristic is flattened can be adjusted.
  • FIGS. 3 and 3a show a flattening of the curve depicting the transmission characteristic of the delay line according to the present invention in the case of a curve which initially has an overly high portion at the low frequency end of the transmission band.
  • the original unflattened curve is shown in dashed lines and the flattened curve resulting from the modification according to the invention is shown in solid lines.
  • FIG. 3a shows the countervoltage AU produced by ultrasonic wave beam 6 for the case where this beam has a path length which is 1.5K shorter than that of the ultrasonic wave beam at that frequency where the strongest attentuation of the output voltage is to occur. It can be seen that this frequency is slightly less than 4 MHz.
  • a ratio of the widths i and g of beams 5 and 6 was chosen of about g/i A to 1/5.
  • FIGS. 4 and 4a shows the flattening of the transmission characteristic curve realized by the present invention, where the peak of the original curve occurs substantially in the center of the frequency transmission band.
  • the unflattened transmission curve is again shown in dashed lines and the transmission curve which has been flattened according to the present invention is shown in solid lines.
  • the step height h is so selected that the difference in path length between the beams 5 and 6, for the center band frequency, is 2.5).
  • the output voltage U is attenuated the most by the countervoltage AU while the output voltage remains practically unchanged at the band edges of 3.4 and 5.2 MHz, because the path lengths there differ by 2 and 3 whole wavelengths, respectively.
  • a height h of about 0.69 mm and in case of FIG. 4 and 4a a height h of about 1.05 mm gave good results.
  • the beam portion 6 which is split away from the ultrasonic beam 4 and which is required for the correction is small compared to the main beam 5.
  • the difference in path length which is produced by the step can be at the center of the frequency band, about 0.5 to 3.5 wavelengths.
  • An ultrasonic delay line composed of a delay member having planar reflecting boundary surfaces and in which an ultrasonic wave beam, transmitted through the delay member between an electromechanical input transducer and an electro-mechanical output transducer, is reflected, at least once, at one of the planar boundary surfaces, the improvement wherein at least one of the planar boundary surfaces is divided into at least two substantially parallel, offset surfaces at a point where said surface is struck by the beam, the ultrasonic wave beam from the input transducer which impinges on said offset portions being reflected as at least two ultrasonic wave beams which travel over paths of different lengths from the input transducer to the output transducer, and said parallel offset surfaces are offset a preselected distance to provide wave beams of selected widths, the ratio of the widths and the differences in path lengths of the wave beams is such that at least one of the reflected ultrasonic wave beams is effective, within a defined frequency range, to produce electric transducers.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
US00175203A 1970-08-28 1971-08-26 Ultrasonic delay line having offset boundary surfaces at point where beam strikes surface Expired - Lifetime US3735292A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702042865 DE2042865B2 (de) 1970-08-28 1970-08-28 Ultraschallverzoegerungsleitung

Publications (1)

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US3735292A true US3735292A (en) 1973-05-22

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US00175203A Expired - Lifetime US3735292A (en) 1970-08-28 1971-08-26 Ultrasonic delay line having offset boundary surfaces at point where beam strikes surface

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US (1) US3735292A (enExample)
AU (1) AU452627B2 (enExample)
BE (1) BE771655A (enExample)
DE (1) DE2042865B2 (enExample)
FR (1) FR2104888B1 (enExample)
GB (1) GB1355199A (enExample)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2596593A1 (fr) * 1986-03-25 1987-10-02 Thomson Csf Procede de suppression des echos parasites dans les lignes a retard electroacoustiques a ondes de volume, et ligne a retard mettant en oeuvre ce procede

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839731A (en) * 1953-01-14 1958-06-17 Bell Telephone Labor Inc Multi-facet ultrasonic delay line
US3071741A (en) * 1960-10-31 1963-01-01 Joseph B Braucr Microwave acoustic delay line
US3522557A (en) * 1963-07-19 1970-08-04 Bell Telephone Labor Inc Acoustic delay line
US3568104A (en) * 1968-12-20 1971-03-02 Gen Electric Sonic delay line device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839731A (en) * 1953-01-14 1958-06-17 Bell Telephone Labor Inc Multi-facet ultrasonic delay line
US3071741A (en) * 1960-10-31 1963-01-01 Joseph B Braucr Microwave acoustic delay line
US3522557A (en) * 1963-07-19 1970-08-04 Bell Telephone Labor Inc Acoustic delay line
US3568104A (en) * 1968-12-20 1971-03-02 Gen Electric Sonic delay line device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2596593A1 (fr) * 1986-03-25 1987-10-02 Thomson Csf Procede de suppression des echos parasites dans les lignes a retard electroacoustiques a ondes de volume, et ligne a retard mettant en oeuvre ce procede
WO1987006073A1 (fr) * 1986-03-25 1987-10-08 Thomson-Csf Procede de supression des echos parasites dans les lignes a retard electroacoustiques a ondes de volume, et ligne a retard mettant en oeuvre ce procede
US4821004A (en) * 1986-03-25 1989-04-11 Thomson-Csf Method for the elimination of spurious echos in electro-acoustic delay lines using bulk waves and delay line applying this method

Also Published As

Publication number Publication date
DE2042865B2 (de) 1972-03-09
GB1355199A (en) 1974-06-05
AU3236971A (en) 1973-02-22
FR2104888B1 (enExample) 1976-09-03
AU452627B2 (en) 1974-09-12
BE771655A (fr) 1971-12-31
FR2104888A1 (enExample) 1972-04-21
DE2042865A1 (enExample) 1972-03-09

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