US3778648A - Piezoelectric transformers - Google Patents

Piezoelectric transformers Download PDF

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Publication number
US3778648A
US3778648A US00267250A US3778648DA US3778648A US 3778648 A US3778648 A US 3778648A US 00267250 A US00267250 A US 00267250A US 3778648D A US3778648D A US 3778648DA US 3778648 A US3778648 A US 3778648A
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United States
Prior art keywords
electrode
base
driving
emitter
electrodes
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Expired - Lifetime
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US00267250A
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English (en)
Inventor
T Kawada
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Denki Onkyo Co Ltd
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Denki Onkyo Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/338—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement
    • H02M3/3381—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement using a single commutation path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1203—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier being a single transistor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1231—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier comprising one or more bipolar transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1296—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the feedback circuit comprising a transformer
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/802—Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
    • H10N30/804—Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits for piezoelectric transformers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
    • H03B5/362—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device the amplifier being a single transistor

Definitions

  • a piezoelectric transformer utilizes a ceramic bar of a ferroelectric material, such as lead titanate zirconate or the like.
  • the ceramic bar is polarized and provided with a pair of opposed driving electrodes at one end and an output electrode at the other end.
  • the piezoelectric bar When applied with a driving voltage across the driving electrodes the piezoelectric barvibrates mechanically.
  • the frequency of the driving voltage is equal or nearly equal to the natural or resonance frequency of the piezoelectric bar, the efficiency is the highest.
  • the vibrating frequency of the piezoelectric bar is determined mainly by the length thereof andis given by the following equation;
  • V is a velocity of sound wave transmitting through the bar and L the length thereof.
  • the vibrating frequency f is determined by the dimensions of the bar. In one example where the bar has dimensions of 56X 3.5 mm, the vibration frequency equals about 31 KHz at a )t/Z mode whereas about 62 KHz at a A mode and the frequency of the driving voltage is determined to be equal or nearly eaual to these vibration frequencies.
  • the resonance frequency of the piezoelectric transformer varies dependent upon the variations not only in the temperature but also in the impedance of the load connected to the output electrode.
  • Another object of this invention is to provide an improved driving circuit for a piezoelectric transformer which is simple in construction and yet can drive stably the piezoelectric transformer.
  • a piezoelectric transformer comprising a piezoelectric member having a pair of driving electrodes at one end and an output electrode at the opposite end of the piezoelectric member, a transistor having a base electrode, a collector electrode and an emitter electrode, a transformer having a primary winding and a secondary winding, means to connect the collector electrode to one pole of a DC source through the primary winding and means to connect in series the secondary winding and the driving electrodes across the base and emitter electrodes of the transistor, thereby forming an oscillation circuit for producing a high frequency driving voltage.
  • FIG. 1 of the accompanying drawing shows the relationship between the driving frequency f and the absolute value of the input impedance I Z l across the driving electrodes and the phase difference P between the driving voltage and driving current.
  • the absolute value of the imput impedance decreases to a minimum at the resonance frequency fr at which the phase difference P between the voltage and current becomes zero.
  • the absolute value of the input impedance I Z l reaches a maximum value at the antiresonance frequency fe at which the phase difference P again reaches zero.
  • a piezoelectric bar 1 is provided with a pair of driving electrodes 11 and 12 applied on the opposite surfaces at one end of the bar and an output electrode 10 applied to the opposite end of the bar.
  • The'primary winding 31 of a transformer 3 is connected to the collector electrode 21 of a transistor 2 whereas the secondary winding 32 is connected in series with the driving electrodes across the base electrode 22 and the emitter electrode 23 of the transistor.
  • the transistor and the transformer constitute an oscillator for generating a high frequency driving voltage. The connection is such that the phase of the collector output is reversed and the phase reversed current is fed back to the base electrode so that increase in the collectorcurrent results in the increase in the base-emitter current.
  • the phase of the output from the collector electrode 21 of transistor 2 is shifted by and the phase shifted output is then applied across the driving electrodes l1 and 12 of the piezoelectric bar 1.
  • the input impedance becomes a minimum.
  • the oscillator is assured to operate at a frequency at which the input impedance is the minimum and the feedback is the maximum or at the reso nance frequency of the piezoelectric bar.
  • FIG. 3 shows a transistor of the base ground type.
  • FIG. 4 shows a detailed connection diagram of one embodiment of the invention.
  • the output electrode 10 of the piezoelectric transformer l' is connected to a load 15 via a suitable rectifier circuit shown as comprising a pair of diodes l3 and 14.
  • the connection between transistor 2 and transformer 3 is identical to that shown in FIG. 2 except that a variable resistor 24 is connected between driving electrode 12 and the base electrode 22.
  • a bias voltage is impressed upon the base electrode 22 from a juncture between resistors 25 and 26.
  • diodes 27 and 28 are provided for protecting the base and collector electrodes, respectively, of the transistor 2.
  • a capacitor 29 is connected between driving electrode 12 which is connected to the base electrode 22 of transistor 2 through variable resistor 24, and the emitter electrode 23 for the purpose of compensating for the phase lag of the signals of the base and collector electrodes which is caused by the charge storage time of the transistor, By a suitable adjustment of resistor 24, the capacitor 29 compensates for such phase lag.
  • the other driving electrode 11 is connected to earth potential E through the secondary winding 32 of transformer 3.
  • the driving circuit is energized from a source of commercial frequency 4 through a bridge rectifier circuit and a smoothing capacitor 41.
  • the chassis is grounded through a capacitor 60 having a capacity of several picofarads.
  • the capacitor 60 exhibits a high reactance for the commercial frequency but a low reactance for the output frequency (for example, 30 to 70 KHz) of the piezoelectric transformer.
  • a resistor 61 having a value of several hundreds kilohms may be connected in parallel with the capacitor 60 to form a shunt circuit for the DC component of the load current.
  • the invention provides an improved piezoelectric transformer provided with a novel driving circuit which is simple in construction, can drive the piezoelectric transformer at high efficiencies and simplifies the construction of the source rectifier.
  • a voltage multiplying rectifier circuit on the output side of the piezoelectric transformer, it is possible to use it for charging devices and dust precipitating apparatus.
  • a piezoelectric transformer comprising a piezoelectric member having a pair of driving electrodes at one end and an output electrode at the opposite end of said piezoelectric member, a transistor having a base electrode, a collector electrode and an emitter electrode, a transformer having a primary winding and a secondary winding, means to connect said collector electrode to one pole of a DC source through said primary winding and means to connect in series said secondary winding and said driving electrodes across the base and emitter electrodes of said transistor, thereby forming an oscillation circuit for producing a high voltage driving voltage, and including a phase adjuster having a variable resistor connected between one of the driving electrodes and said base electrode and a capacitor connected between said one driving electrode and said emitter electrode.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
US00267250A 1971-07-05 1972-06-28 Piezoelectric transformers Expired - Lifetime US3778648A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46049448A JPS5221173B1 (pt) 1971-07-05 1971-07-05

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US3778648A true US3778648A (en) 1973-12-11

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US (1) US3778648A (pt)
JP (1) JPS5221173B1 (pt)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4114194A (en) * 1976-04-22 1978-09-12 Clairol, Inc. Ultrasonic cleaner
US4139842A (en) * 1977-04-14 1979-02-13 Nobuhiko Fujita Audible alarm unit
US4575654A (en) * 1984-10-01 1986-03-11 General Electric Company Piezoceramic coupler control circuit
US5329200A (en) * 1992-07-17 1994-07-12 Nec Corporation Piezoelectric transformer converter for power use
EP0730338A1 (en) * 1995-03-03 1996-09-04 SECI SUD S.r.l. Piezoelectric double-polarization resonating transformer for low-power, high-voltage power supply
EP0706306A3 (en) * 1994-10-05 1997-12-10 Nec Corporation A hardware arrangement and method of driving a piezo-electric transformer
US5705877A (en) * 1995-10-12 1998-01-06 Nec Corporation Piezoelectric transformer driving circuit
US5866968A (en) * 1997-05-07 1999-02-02 Motorola Inc. Single-input phase locking piezoelectric transformer driving circuit
US6819028B2 (en) * 2000-03-21 2004-11-16 Murata Manufacturing Co., Ltd. Method for selecting piezoelectric transformer characteristic
US9999778B2 (en) 2009-08-11 2018-06-19 Koninklijke Philips N.V. Non-magnetic high voltage charging system for use in cardiac stimulation devices
US10840853B2 (en) 2019-02-26 2020-11-17 Keysight Technologies, Inc. Low phase noise oscillator using negative feedback

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054967A (en) * 1958-12-31 1962-09-18 Ibm Free-running pulse generator for producing steep edge output pulses
US3277465A (en) * 1963-02-25 1966-10-04 Bronson M Potter Electrically operated audible alarm
US3302131A (en) * 1966-05-09 1967-01-31 Lawrence A Pyatt Transformer-coupled emitter-follower oscillator
US3382447A (en) * 1966-10-18 1968-05-07 Sanders Associates Inc Ultrastable crystal-controlled transistor oscillator-multiplier
US3435368A (en) * 1965-03-06 1969-03-25 Hattori Tokeiten Kk Low frequency piezoelectric crystal oscillator having a single driving circuit
US3524082A (en) * 1967-12-01 1970-08-11 Hal C Mettler Oscillatory energy generating apparatus
US3598909A (en) * 1967-07-25 1971-08-10 Matsushita Electric Ind Co Ltd A high-voltage generator circuit configuration utilizing a ceramic transformer
US3657579A (en) * 1971-04-16 1972-04-18 Motorola Inc Power supply circuit employing piezoelectric voltage transforming device
US3679918A (en) * 1969-12-30 1972-07-25 Denki Onkyo Co Ltd Self-exciting type high voltage generating apparatus utilizing piezolectric voltage transforming elements
US3689781A (en) * 1969-11-22 1972-09-05 Denki Onkyo Co Ltd Voltage transforming devices utilizing piezoelectric elements

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054967A (en) * 1958-12-31 1962-09-18 Ibm Free-running pulse generator for producing steep edge output pulses
US3277465A (en) * 1963-02-25 1966-10-04 Bronson M Potter Electrically operated audible alarm
US3435368A (en) * 1965-03-06 1969-03-25 Hattori Tokeiten Kk Low frequency piezoelectric crystal oscillator having a single driving circuit
US3302131A (en) * 1966-05-09 1967-01-31 Lawrence A Pyatt Transformer-coupled emitter-follower oscillator
US3382447A (en) * 1966-10-18 1968-05-07 Sanders Associates Inc Ultrastable crystal-controlled transistor oscillator-multiplier
US3598909A (en) * 1967-07-25 1971-08-10 Matsushita Electric Ind Co Ltd A high-voltage generator circuit configuration utilizing a ceramic transformer
US3524082A (en) * 1967-12-01 1970-08-11 Hal C Mettler Oscillatory energy generating apparatus
US3689781A (en) * 1969-11-22 1972-09-05 Denki Onkyo Co Ltd Voltage transforming devices utilizing piezoelectric elements
US3679918A (en) * 1969-12-30 1972-07-25 Denki Onkyo Co Ltd Self-exciting type high voltage generating apparatus utilizing piezolectric voltage transforming elements
US3657579A (en) * 1971-04-16 1972-04-18 Motorola Inc Power supply circuit employing piezoelectric voltage transforming device

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4114194A (en) * 1976-04-22 1978-09-12 Clairol, Inc. Ultrasonic cleaner
US4139842A (en) * 1977-04-14 1979-02-13 Nobuhiko Fujita Audible alarm unit
US4575654A (en) * 1984-10-01 1986-03-11 General Electric Company Piezoceramic coupler control circuit
US5329200A (en) * 1992-07-17 1994-07-12 Nec Corporation Piezoelectric transformer converter for power use
EP0706306A3 (en) * 1994-10-05 1997-12-10 Nec Corporation A hardware arrangement and method of driving a piezo-electric transformer
EP0730338A1 (en) * 1995-03-03 1996-09-04 SECI SUD S.r.l. Piezoelectric double-polarization resonating transformer for low-power, high-voltage power supply
US5705877A (en) * 1995-10-12 1998-01-06 Nec Corporation Piezoelectric transformer driving circuit
US5859489A (en) * 1995-10-12 1999-01-12 Nec Corporation Piezoelectric transformer driving circuit
US5866968A (en) * 1997-05-07 1999-02-02 Motorola Inc. Single-input phase locking piezoelectric transformer driving circuit
US6819028B2 (en) * 2000-03-21 2004-11-16 Murata Manufacturing Co., Ltd. Method for selecting piezoelectric transformer characteristic
US9999778B2 (en) 2009-08-11 2018-06-19 Koninklijke Philips N.V. Non-magnetic high voltage charging system for use in cardiac stimulation devices
US10840853B2 (en) 2019-02-26 2020-11-17 Keysight Technologies, Inc. Low phase noise oscillator using negative feedback

Also Published As

Publication number Publication date
JPS5221173B1 (pt) 1977-06-08

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