US3376521A - Mechanical vibrator with electrostrictive excitation - Google Patents

Mechanical vibrator with electrostrictive excitation Download PDF

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Publication number
US3376521A
US3376521A US368717A US36871764A US3376521A US 3376521 A US3376521 A US 3376521A US 368717 A US368717 A US 368717A US 36871764 A US36871764 A US 36871764A US 3376521 A US3376521 A US 3376521A
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Prior art keywords
blocks
vibrator
harmonic
harmonics
bending
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Expired - Lifetime
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US368717A
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English (en)
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Traub Karl
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Siemens AG
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Siemens AG
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Priority to US717325A priority Critical patent/US3486136A/en
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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 devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/56—Monolithic crystal filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator

Definitions

  • the invention relates to a mechanical vibrator which is formed by small plates or blocks of electrostrictive material for the transition from electrical oscillations to mechanical bending or longitudinal vibrations and vice versa, and is preferably provided as an end vibrator of a multipart mechanical filter, in which the blocks of electrostrictive material are specifically arranged within an area limited by two vibration nodes with plane of the block extending perpendicular to the longitudinal axis of the vibrator.
  • Mechanical resonators due to stability and their high quality, can be used to advantage in oscillator circuits and filter circuits in which the requirements with respect to frequency precision or steepness of the filter flanks can be fulfilled, only with difiiculty, with lumped circuit elements.
  • a mechanical resonator has, as a rule, the form of an acoustic conduction line in which there holds for it only in a relatively narrow frequency range the electric equivalent circuit diagram representing a resonant circuit. If a mechanical resonator is to be utilized for a large frequency range, its input resistance, in contrast to a resonant circuit from lumped circuit elements, shows continuously repeating null and pole points which are evoked by the so-called harmonics of the resonator.
  • a mechanical vibrator which is formed by small plates or blocks of electrostrictive material for the transition from electric vibrations to mechanical bending or longitudinal vibrations and vice versa and is preferably provided as an end vibrator of a multi-part mechanical filter, and in which the blocks of electrostrictive material are arranged predominantly substantially within the space extending between two vibration nodes, with the block plane lying perpendicular to the longitudinal axis of the vibrator, such problem is solved according to the invention, by an arrangement such that the plates or blocks of electrostrictive material are located at points of the vibrator at which no deformation occurs in the harmonic to be suppressed and/ or that several blocks are so located at different points of the vibrator that the forces effective in the vibration excitation very nearly completely cancel each other out for the harmonics to be suppressed.
  • the blocks of electrostrictive material are arranged in the central portion of the vibrator, or if such blocks are arranged symmetrically to the center of the vibrator.
  • the blocks of electrostrictive material are interrupted adjacent the neutral axis with respect to bending vibrations, and if the blocks disposed on both sides of the neutral point are oppositely polarized, or if the blocks of electrostrictive material are subdivided by a metal coating, preferably a silver coating, which runs parallel to the limit surfaces established through length and width of the blocks and if these conducting layers are provided with connecting wires.
  • FIGS. 1 to 5 are graphs of deformation vibrations in a bending vibrating bar for a fundamental frequency and certain harmonics
  • FIG. 6 illustrates a mechanical bending vibrator constructed in accordance with the invention
  • FIGS. 7 and 8 illustrate additional embodiments of the invention
  • FIG. 9 illustrates the electrical equivalent circuit of the construction illustrated in FIG. 6;
  • FIG. 10 illustrates an additional modification of the invention
  • FIG. 11 illustrates an electrical equivalent circuit for the construction illustrated in FIG. 10
  • FIGS. 12 and 13 illustrate additional embodiments of the invention in bending vibrators
  • FIG. 14 is a graph, similar to FIGS. 1-5, of deformation vibrations in a longitudinally vibrating bar for a fundamental frequency and certain harmonics;
  • FIG. 15 illustrates a mechanical longitudinal vibrator constructed in accordance with the invention.
  • E signifies the elasticity modulus of the vibrator material
  • I the moment of inertia of the bar in the vibrational direction
  • m the mass per unit of length
  • l the length of the bar
  • n the order number of the resonance frequency
  • FIGS. 1 to 5 the deformation and the position of the vibration nodes are plotted in dependence on a coordinate x/l, with x signifying an arbitrary point on the bar.
  • FIG. 6 illustrates a mechanical bending vibrator, which is constructed, as to the manner of excitation of the mechanical bending vibrations, in a known manner by means of electrostrictive ceramic blocks.
  • a steel bar 5 is provided, at both sides of the point which is neutral with respect to bending vibrations, with electrostrictively active blocks 6 and '7.
  • electrostrictively active material lead ceramic lead zirconate
  • the ceramic blocks are provided on the sides facing the steel portions with a silver coating and are firmly soldered to such steel portions.
  • the polarization of the ceramic plates is indicated by the arrows 8 and 9 and is so selected that the block 6, disposed above the neutral axis, is oppositely polarized to the block 7 lying below the neutral axis.
  • metal lead wires 12 and 13 are attached, which extend to corresponding connecting terminals 1 and 2.
  • the lead wires 12 and 13, if of corresponding thick structure, can also be utilized for supporting the vibrator in a casing (not illustrated).
  • the polarization direction of the ceramic block 6 is opposed to the electric field direction, while the polarization direction of block 7 corresponds with the direction of the electric field.
  • the one block expands itself under the influence of the electric field, while the other block contracts, whereby the vibrator is bent to one side, If the polarity of the applied alternating potential is reversed, then correspondingly the vibrator is bent to the other side, so that it executes pronounced bending vibrations if the frequency of the applied alternating potential agrees at least approximately with its own characteristic frequency.
  • the ceramic blocks are mounted in the middle of the bar (that is, at 0.5.1).
  • the electrostrictively active systems are arranged symmetrical to the center of the bar and to the portions of the steel vibrator 5 there are soldered ceramic blocks 15, 16, 17 and 18.
  • lead wires 12 and 12' which extend to a common connecting terminal 1.
  • an additional lead wire 19 which extends to a connecting terminal 2.
  • the polarization of the ceramic blocks is indicated by the arrows 20, 21, 22 and23, and again is so selected that the blocks lying above the neutral axis are polarized oppositely to the blocks lying below the neutral axis, with the polarization directions of the two systems being opposed to each other.
  • the vibrator executes mechanical bending vibrations when an electric alternating potential is applied to the terminals 1 and 2, whose frequency agrees with its resonance frequency.
  • FIG. 9 there is depicted the electrical equivalent circuit diagram of such bending vibrators.
  • the fundamental can be represented by a series resonance circuit including inductance LI, the capacity C and a loss resistance R with a capacitance C being connected in parallel with such series circuit.
  • the connecting terminals are designated 1 and 2,, for the possible harmonics occurring on the mechanical vibrators there are indicated, in broken lines, in the equivalent circuit diagram additional series vibration circuits with the circuit elements L C and R to L C and R
  • FIG. 7 by reason of the polarization indicated by arrows 20 to 23
  • T he embodiment illustrated in FIG. 8 corresponds in its construction to that of FIG. 7, the only difference being in the selection of polarization direction for the individual electrostrictively active blocks 15, 16, 17 and 18.
  • the polarization is indicated by arrows 2t)", 21', 22. and 23' and is so selected that the blocks lying above the neutral axis are polarized oppositely to the blocks lying below the neutral axis. However, for both systems the blocks lying above and below the neutral axis are polarized in the same direction.
  • the electrostrictively active blocks are subjected to expansions and contractions, so that the vibrator executes bending vibrations in reference to the polarization direction.
  • FIG. 10 a mechanical bending vibrator is represented, whose excitation takes place over electrostrictively active blocks of calcium-barium-titanate, whose Curie temperature, as is Well known, is lower than the requisite soldering temperature. For this reason the electrostrictively acting blocks 30, 31, 32, 33, 34, 35, 36 and 3 7 are correspondingly subdivided by silver layers 38, 39, 4t) and 41.
  • the vibrator 5 By applying a direct potential to corresponding silver layers and parts the vibrator 5 it is possible then to impress on the ceramic blocks, according to the soldering process, the polarization suited for the particular purpose in use.
  • lead wires 42 and 43 are attached, which, if suitably proportioned as to thickness, can also serve for the supporting of the vibrator in a casing (not illustrated), and which lead wires are then connected by means of a suitable connecting line to a common conecting terminal 1.
  • a connecting wire 44 Leading from the middle portion of the vibrator 5 is a connecting wire 44, which extends to a connecting terminal 2, and leading from the silver layers 38 to 41 and connecting wires 4'5, 46, 47 and 48 which extend to a common connecting terminal 3.
  • the polarization direction of the individual ceramic blocks is indicated by the arrows 49 to 56 is made such that the blocks located above the neutral axis are polarized oppositely to the blocks located below the neutral axis.
  • the connecting terminals 1 and 3 If there is applied to the connecting terminals 1 and 3 an input alternating voltage U whose frequency roughly corresponds with the frequency of the bending vibrator, the latter will execute bending vibrations in the rhythm of the applied alternating voltage, since the blocks .32 and 37, for example, lying above the neutral axisexpand, while the blocks and lying below the neutral axis contract. If the polarity of the applied alternating voltage is reversed, the blocks lying above the neutral axis contract, while the blocks lying below the neutral axis expand.
  • the blocks 31, .33, 34 and 36 are also subjected to expansions and contractions; so that between the silver layers 38 to 41 and the middle portion of the vibrator 5 a voltage appears, which can be obtained as an output alternating voltage U across the terminals 2 and 3.
  • FIG. 11 The electrical equivalent circuit diagram of a vibrator according to FIG. 10 is depicted in FIG. 11. It consists, for the fundamental, of a circuit in-whose longitudinal branch there is a loss-loaded series resonant circuit with the inductance L' the capacitance (1' and the nonreactive resistance R' and in which at the input and output there are approximately equal shunt capacitance C and CO disposed.
  • a difference in thickness of the electrostrictive blocks, or a difference in their polarization there is inserted in the output circuit, ahead of the output cross capacity C an ideal transformer U with the transformation ratio 1:U.
  • the connecting terminals are designated with 1' 2',, and 3',,.
  • the embodiment illustrated in FIG. 10 can also be operated, in analogy with the equivalent circuit diagram of FIG. 9, in the manner of a bipole, if the terminals 1 and 2 are connected with each other and the exciting voltage is applied to the terminals 3 and the connecting line between terminals 1 and 2.
  • an end vibrator in which the third and all even numbered harmonics are not excited.
  • FIG. 12 a mechanical bending vibrator is illustrated, whose excitation systems consist of a lead ceramic.
  • FIG. 13 in further development of the concept of the invention, there is represented a mechanical bending vibrator operated as a quadrupole, in which the third and fifth harmonics as well as all the even numbered harmonics are suppressed.
  • the steel portions of the vibrator 5 are here connected with each other over respective pairs of blocks and 76, 77, 79 and 80, 81 and 82 of a lead ceramic, the polarization of the individual blocks being indicated .by the arrows 83 to and so selected that in each case the blocks located above the neutral axis are polarized oppositely to the blocks located below the neutral axis, and moreover, the blocks located in the left hand half of the bar are polarized oppositely to the blocks located in the right hand half of the bar.
  • the blocks 75 and 76 and also the blocks 81 and 82 are so arranged that they are positioned in vibration nodes of the third harmonic (b 0.3561) Blocks 77, 78, 79 and 80 lie in vibration nodes of the fifth harmonic (x/l 0.409). From the individual steel portions of the vibrator extend connecting wires 91 and 92 to a terminal 1, a connecting wire 93 to a terminal 2 and connecting wires 94 and 95 to a terminal 3.
  • the equivalent circuit diagram of this vibrator likewise can be considered with respect to FIG. 11. If there is applied between terminals 1 and 3 an input alternating potential U, by reason of the excitation system. consisting of the blocks 75, 76, 81 and 82, the vibrator then executes bending vibrations, through which the blocks 77 and 78, as well as the blocks 79 and 80 are expanded and contracted. It is possible, therefore, to obtain between terminals 2 and 3 an output alternating voltage U,,. Since the blocks forming the excitation system are located in the vibration nodes of the third harmonic, the latter is not excited, and as the output voltage is derived over ceramic blocks which are positioned in vibration nodes of the fifth harmonic, frequencies corresponding to this harmonic are not contained in the output voltage. Moreover, as a result of the symmetry of the arrangement, no even numbered harmonics are even initially excite-d.
  • the electrostriotively active systems are disposed symmetrically to the center of the vibrator and at least approximately symmetrically to the vibration nodes of the third harmonic.
  • the longitudinal symmetry occurring with reference to the vibration of the third harmonic can be compensated with respect to the electrical operation, by suitable selection of the thickness of the plates 75 and 76 and 81 and 82 whereby they differ from the thickness of plates 77 and 78, and 79 and 80, respectively.
  • FIG. 14 the deformation and the position of the vibration nodes of a longitudinal vibrator are plotted in dependence on a running coordinate x/l, when x is an arbitrary point and l signifies the bar length.
  • the curve 100 represents the deformation for the fundamental, the curve 101 the deformation for the second harmonic and curve 102 the deformation for the third harmonic.
  • the higher frequencies occur harmonically to the fundamental, as is apparent also from the diagram of FIG. 14.
  • FIG. 15 a longitudinal vibrator is depicted which consists of a steel portion 105, into which electrostrictively active blocks 106 and 107 are soldered in known manner, the polarization of these blocks being indicated by the arrows 108 and 109. From the steel portions insulated from one another by the ceramic blocks connecting wires 110, 111 and 112 extend to respective terminals 1, 2 and 3.
  • the electrical equivalent circuit diagram of such a longitudinal vibrator can be considered with respect to FIG. 11. If an input alternating voltage U is applied between terminals 1 and 3, the vibrator executes longitudinal vibrations, since the exciting ceramic block 108 extends across the entire cross section of the vibrator, and since the excitation system lies in a vibration node of the third harmonic, this is not excited.
  • the frequency of the exciting voltage corresponds, for example, with the resonant frequency of the vibrator
  • An electromechanical filter having an elongated metallic vibrator for the transition of electrical oscillations to longitudinal vibrations, and blocks of electrostrictive material disposed along the length of the metallic vibrator, said blocks of electrostrictive material extending perpendicular to the longitudinal axis of said vibrator and polarized in the direction of the longitudinal axis, wherein the improvement comprises at least one block at the mid point of the metallic vibrator and a second block at a vibration node of an odd-numbered harmonic.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
US368717A 1963-05-21 1964-05-19 Mechanical vibrator with electrostrictive excitation Expired - Lifetime US3376521A (en)

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Application Number Priority Date Filing Date Title
US717325A US3486136A (en) 1964-05-19 1968-03-29 Mechanical vibrator with electrostrictive excitation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES85317A DE1277463B (de) 1963-05-21 1963-05-21 Mechanischer Schwinger mit elektrostriktiver Anregung

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US (1) US3376521A (nl)
AT (1) AT261682B (nl)
BE (1) BE648208A (nl)
CH (1) CH430901A (nl)
DE (2) DE1616526B2 (nl)
FR (1) FR1395326A (nl)
GB (1) GB1073963A (nl)
NL (1) NL140115B (nl)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3686593A (en) * 1969-03-07 1972-08-22 Int Standard Electric Corp Electromechanical resonator
US3842294A (en) * 1972-11-08 1974-10-15 Nippon Electric Co Electromechanical transducer comprising a pair of antiparallel poled rectangular piezoelectric ceramic pieces
US4281298A (en) * 1978-10-13 1981-07-28 Fujitsu Limited Flexural transducer
US5006824A (en) * 1986-04-07 1991-04-09 Rockwell International Corporation Third mode torsional F-M resonator
US5773912A (en) * 1995-12-19 1998-06-30 Murata Manufacturing Co., Ltd. Piezoelectric resonator including oscillation buffer materials
US20140184029A1 (en) * 2013-01-02 2014-07-03 Industrial Technology Research Institute Microelectromechanical system-based resonator device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3423492A1 (de) * 1984-06-26 1986-01-02 Siemens AG, 1000 Berlin und 8000 München Elektromechanischer wandlerresonator zur erzeugung mechanischer biegeschwingungen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3015789A (en) * 1956-04-23 1962-01-02 Toyotsushinki Kabushiki Kaisha Mechanical filter
US3028564A (en) * 1960-06-14 1962-04-03 Kokusai Electric Co Ltd Mechanical filter
US3293575A (en) * 1961-09-29 1966-12-20 Siemens Ag Electromechanical filter having means to reduce harmonic transmission
US3311760A (en) * 1963-11-21 1967-03-28 Westinghouse Electric Corp High q resonator

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1747837A (en) * 1925-08-05 1930-02-18 Western Electric Co Oscillation generator
US2569460A (en) * 1946-05-23 1951-10-02 Bendix Aviat Corp Magneto
GB840815A (en) * 1957-03-06 1960-07-13 Gen Electric Co Ltd Improvements in or relating to electro-mechanical resonators

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3015789A (en) * 1956-04-23 1962-01-02 Toyotsushinki Kabushiki Kaisha Mechanical filter
US3028564A (en) * 1960-06-14 1962-04-03 Kokusai Electric Co Ltd Mechanical filter
US3293575A (en) * 1961-09-29 1966-12-20 Siemens Ag Electromechanical filter having means to reduce harmonic transmission
US3311760A (en) * 1963-11-21 1967-03-28 Westinghouse Electric Corp High q resonator

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3686593A (en) * 1969-03-07 1972-08-22 Int Standard Electric Corp Electromechanical resonator
US3842294A (en) * 1972-11-08 1974-10-15 Nippon Electric Co Electromechanical transducer comprising a pair of antiparallel poled rectangular piezoelectric ceramic pieces
US4281298A (en) * 1978-10-13 1981-07-28 Fujitsu Limited Flexural transducer
US5006824A (en) * 1986-04-07 1991-04-09 Rockwell International Corporation Third mode torsional F-M resonator
US5773912A (en) * 1995-12-19 1998-06-30 Murata Manufacturing Co., Ltd. Piezoelectric resonator including oscillation buffer materials
US20140184029A1 (en) * 2013-01-02 2014-07-03 Industrial Technology Research Institute Microelectromechanical system-based resonator device
US9013089B2 (en) * 2013-01-02 2015-04-21 Industrial Technology Research Institute Microelectromechanical system-based resonator device

Also Published As

Publication number Publication date
FR1395326A (fr) 1965-04-09
NL6405540A (nl) 1964-11-23
CH430901A (de) 1967-02-28
DE1277463B (de) 1968-09-12
DE1616526A1 (de) 1971-04-29
NL140115B (nl) 1973-10-15
GB1073963A (en) 1967-06-28
DE1277463C2 (nl) 1977-06-30
AT261682B (de) 1968-05-10
DE1616526B2 (de) 1972-05-18
BE648208A (nl) 1964-11-23

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