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WO1997023005A1 - Commande de transducteur couple resonnant - Google Patents

Commande de transducteur couple resonnant Download PDF

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Publication number
WO1997023005A1
WO1997023005A1 PCT/US1996/019426 US9619426W WO9723005A1 WO 1997023005 A1 WO1997023005 A1 WO 1997023005A1 US 9619426 W US9619426 W US 9619426W WO 9723005 A1 WO9723005 A1 WO 9723005A1
Authority
WO
WIPO (PCT)
Prior art keywords
transducer
circuit
switch
resonant
driver circuit
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.)
Ceased
Application number
PCT/US1996/019426
Other languages
English (en)
Inventor
Carl Rutschow
Richard A. Arseneau
Russell C. Watts
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch LLC
Original Assignee
Robert Bosch LLC
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
Application filed by Robert Bosch LLC filed Critical Robert Bosch LLC
Priority to AU12816/97A priority Critical patent/AU1281697A/en
Publication of WO1997023005A1 publication Critical patent/WO1997023005A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones

Definitions

  • the present invention relates generally to the field of electronic circuitry, and more particularly to an improved method for providing an increased drive voltage to an acoustic transducer.
  • transformers are generally quite bulky, heavy, and expensive components as compared to most other electronic component devices Furthermore, transformers are generally quite inefficient, and thus produce even more bulk in a finished appliance, given that space for heat dissipation must be provided Therefore, while there remains, and probably will continue to remain, a place for the transformer m specific electronic design applications, it is accepted that avoidance of the use of transformers is frequently a superior design alternative in the creation of modern sophisticated electronic devices.
  • capacitor' circuits such as voltage doublers and voltage multipliers are today frequently employed for stepping up DC voltages
  • a specific problem is posed by those transducers which require a high alternating current (“AC”) drive voltage riding on a direct current (“DC”) bias voltage.
  • AC alternating current
  • DC direct current
  • some transducers such as those used for ultrasonic acoustic ranging, require a high voltage sine wave drive when used as transmitters.
  • a DC bias must also be provided such that the, typically approximately 200 volts peak-to-peak, signal does not drop below zero volts. When such a transducer is used as a receiver, it is still required to provide the high DC bias voltage in order to achieve optimal sensitivity.
  • all prior means for providing this sort of signal/bias combination has involved the use of a
  • acoustic transducer driver circuit which, using the inherent resonance in the transducer along with an inductor and an additional capacitor as a resonant circuit provides a high voltage alternating, generally sine wave shaped, signal to the transducer such that the signal, once initiated, does not drop below zero volts reference.
  • the cycle is periodically disturbed, to put the transducer in a receive mode, generally at the signal peak such that a high static voltage remains on the transducer during the receive mode.
  • a tickle switch is provided for maintaining energy in the resonant circuit during operation thereof.
  • the resonant circuit is electrically tuned to the frequency of the signal being applied to the transducer such that reflected voltages from the capacitor are effectively added to initial signal voltages.
  • An advantage of the present invention is that there are no bulky transformer connections such as are prone to loosen or break when subjected to repeated vibration or other stress.
  • a further advantage of the present invention is that it is efficient, and thus does not give off a substantial amount of heat nor use a significant amount of power to perform its function.
  • Still another advantage of the present invention is that it is small and light weight.
  • Yet another advantage of the present invention is that it is inexpensive to manufacture.
  • Still another advantage of the present invention is that it is reliable in operation.
  • Yet another advantage of the present invention is that DC bias voltages and AC drive signals are coupled to a transducer using a minimum of components.
  • Still another advantage of the present invention is that a coupling circuit for driving a transducer requiring both signal and bias voltages can be constructed into an integrated circuit package.
  • Yet another advantage of the present invention is that the coupling circuit can be electrically tuned, thereby avoiding the need for trimming inductor and capacitor values.
  • Fig. 1 is basic schematic of an acoustic resonant
  • Fig. 2 is a timing diagram illustrative of the functioning of the acoustic resonant coupling circuit of Fig. 1;
  • Fig. 3 is a schematic of an equally preferred alternate embodiment of an acoustic resonant coupling circuit according to the present invention.
  • the best presently known mode for carrying out the invention is a resonant acoustic transducer coupling circuit.
  • the predominant expected usage of the inventive resonant acoustic transducer coupling circuit is in the production of sensor modules using an acoustic signal, where size, weight, cost and accuracy of signal are each important factors.
  • transducer coupling circuit is shown in schematic form in Fig. 1, and is designated therein by the general reference
  • the resonant acoustic transducer coupling circuit 10 has a first diode 12, a second diode 14, a first switch 16, a second switch 18, a third switch 20, a capacitor 22, an inductor 24, and a DC supply voltage 26 having a value V + .
  • V + 12 VDC .
  • the inventive resonant acoustic transducer coupling circuit is depicted connected to a
  • transducer 28 A ground potential 30 is indicated, where present, in the generalized schematic of Fig. 1.
  • a transducer capacitance 32 is indicated in the schematic of Fig. 1.
  • capacitance 32 does not represent a distinct physical
  • the transducer capacitance 32 is the inherent capacitance of the transducer 28.
  • the inductor 24, the capacitor 22 and the transducer capacitance 32 form a tank series resonant circuit ("tank circuit") 34.
  • the switches 16, 18 and 20 are MOS insulated gate field effect (“IGFET”) transistors. Biasing and timing circuit portions for providing operating power to, and for turning off and on the switches 16, 18 and 20, are entirely conventional and are eliminated from the simplified view of
  • IGFET insulated gate field effect
  • the transducer 28 is a
  • the value of the capacitor 22 is chosen to also be 600 ⁇ F .
  • the value of the inductor 24 is 35 mH.
  • the first capacitor 22 is selected to be approximately equal in value to the transducer capacitance 32 of the transducer 28.
  • the inductor 24 is chosen such that the tank series resonant frequency of the inductor 25, the capacitor 22 and the transducer capacitance 32 is slightly above the mechanical resonant frequency of the transducer 28.
  • Fig. 2 is a timing diagram illustrating a typical operating timing pattern of the resonant acoustic transducer coupling circuit 10 of Fig. 1 depicting a resultant signal 35 as seen at the transducer 28.
  • transmission from the transducer 28 is initiated at an initiate operation time 36 when the first switch '"S1") 16 is closed, the second switch (“S2") 18 and the third switch ("S3") 20 being open at the initiate
  • I term the desired current level
  • the first switch 16 is opened at a begin cycling time 38.
  • energy stored in tne inductor 24 is described by the term 1 ⁇ 2LI term 2 .
  • the stored energy in the inductor 24 then begins to resonantly charge the transducer capacitance 32 to a voltage dependant upon the amount of energy then stored in the
  • V c is approximately 200 volts.
  • the second switch 18 acts as a "tickle" switch.
  • the third switch 20 is opened at a prepare for tickle time 42 and the second switch 18 is closed at a start tickle time 44.
  • the third switch 20 remains open and the second switch 18 remains closed during all or part of the half cycle when the capacitor 22 is discharging through the
  • the second switch 18 is opened at an end tickle time 46 and, thereafter, the third switch 20 is closed at an allow further cycling time 48.
  • tickle 50 raises the voltage on the ground side of the capacitor 22 which has the same effect as would increasing the discharge voltage across the inductor by V + volts. This increases the current in the inductor 24 (and, consequently, the energy stored in the inductor 24) according to the tickle 50.
  • Equation I V + t 2 /L where t 2 is the time that the second switch 18 is closed The time t 2 can be adjusted such that the energy injected into the tank circuit 34 just replaces energy lost through attrition.
  • the oscillation In order to place the transducer 28 in the receive mode, the oscillation must be stopped with a high DC voltage left remaining across the transducer capacitance 32. This is accomplished by opening the third switch 20 at any point in that half cycle when the capacitor 22 is discharging into the transducer capacitance 32 through the inductor 24, with both the first switch 16 and the second switch 18 being left open, as is indicated occurring at a start hold time 52. The tank circuit 34 will then finish the half cycle through the second diode 14 until the capacitor 22 is discharged and the
  • transducer capacitance 32 is at its maximum voltage.
  • the hold time 56 can also be used to slightly adjust (lower) the frequency of oscillation of the tank circuit 34 so that the electrical oscillation period matches the mechanical resonant frequency of the transducer 28. This is desirable, since any
  • trans ⁇ ucer such as the transducer 28 generally is most efficient when the electrical oscillation frequency is matched to its mechanical resonant frequency. This objective is achieved by selecting a component value for the inductor 24 such that, when used as described and shown herein with the capacitor 22 and the transducer capacitance 32 causes the tank circuit 34 to have an electrical resonant frequency slightly higher than the mechanical resonant frequency of the
  • the oscillation period of the tank circuit 22 can then be periodically increased, as required, by
  • this adjustment is made during each cycle of oscillation of the tank circuit 34, although it is conceivable that the desired result could be obtained by making such adjustment at intervals of less than every cycle.
  • the first is to restart the oscillation as has previously been disclosed herein, by closing the first switch 16. This discharges the transducer capacitance 32 and allows current to build up in the inductor 24.
  • the second preferred method for restarting operation is to reclose the third switch 20. The tank circuit 38 will then commence oscillation upon the energy stored in the transducer
  • the second switch 18 can then be used to tickle the tank circuit 34 in order to restore the resonant acoustic transducer coupling circuit 10 to the desired energy level.
  • the resonant acoustic transducer coupling circuit 10 has been simulated using Simulation Program with Integrated
  • SPICETM Circuit Emphasis
  • FIG. 2 The timing diagram of Fig. 2 is derived from the SPICE simulation. As can be seen in the view of Fig. 2, an inductor current trace (“I c ”) 58 shows that current begins building up in the inductor 24 when the first switch 16 is closed and that reverse current begins to flow in the inductor generally simultaneously with the opening of the first switch 16.
  • I c inductor current trace
  • microprocessor control will in most applications, be derived from a processor (not shown) which is generally available for the operation and control of a larger object detection or location circuit, or the like, of which the resonant acoustic transducer coupling circuit 10 will form a component part thereof.
  • Fig. 3 is a basic schematic diagram of an equally
  • the alternate preferred embodiment 10a provides comparable performance at a lower cost in that, for example, fewer switches and diodes are required.
  • the second diode 14, the first switch 16, the capacitor 22, the inductor 24, the transducer 28 (and associated transducer capacitance 32), the ground potential 30 and the receiver electronics 54 are retained in the equally preferred alternate embodiment 10a and these have essentially the same functionality therein as has been previously described in relation to the first described embodiment 10 of the present invention.
  • an alternate DC supply voltage 26a provides
  • a modified tank circuit 34a has a second capacitor 58 added thereto.
  • resistor 60 limits current from the alternate DC supply voltage 26a in the equally preferred alternate embodiment 10a of the invention.
  • the alternative resonant acoustic transducer coupling circuit 10a lacks components for rapidly causing the decay and/or hold of resonance of the alternative tank circuit 34a. Similarly, the alternative resonant acoustic transducer coupling circuit 10a lacks components for "tickling" the alternative tank circuit 10a as has been previously described herein in relation to the first preferred embodiment 10 of the present invention.
  • the equally preferred alternate embodiment 10a of the present invention functions much like the operation previously described herein in relation to the first preferred embodiment 10.
  • Oscillation of the tank alternative tank circuit 34a is induced by the introduction of a pulse width modulated signal across the first switch 16, which excites the alternate resonant circuit 34a, producing a large voltage swing between the capacitor 22 and the inductor 24.
  • the oscillating signal is clamped to the ground potential 30 by the diode 14. This clamping stores charge on the transducer capacitance 32 and the capacitor 22, producing an offset bias that is approximately one half of the peak to peak signal swing.
  • the capacitor 22 is chosen to maintain bias in the presence of leakage current through the diode 14 and other parasitic paths during the receive portion of the operation.
  • the current limiting resistor 60 value is chosen to limit the current through the first switch 16 to a value tolerable thereby
  • the second (coupling) capacitor 58 is introduced to provide additional wave shaping to monimize low frequencies in the output excitation pulse presented to the transducer 28.
  • transducer 28 called forth in this disclosure. Where another transducer might be adapted for use with the present
  • component values and circuit timings will be adjusted, accordingly, with only a minimal amount of
  • the inventive resonant acoustic transducer coupling circuit is intended to be widely used wherever it is desirable to provide an AC drive signal riding on a DC bias voltage.
  • the predominant current usages are for providing signal and bias to acoustic transducers used for distance measurement, and the like, particularly the Polaroid 9000 SeriesTM
  • the primary intended use for the inventive resonant acoustic transducer coupling circuit 10 is in an automobile, for operation in cooperation with a transducer, receiver and microprocessor to comprise a position locating sonar type apparatus which will determine if a person is seated in a seat of the automobile and, if so, whether the person is facing forward, what size the person is, and other information necessary for making a decision about whether an air bag should be deployed when other sensors determine that an accident condition exists, such as for example as is
  • EMI Electro-Mechanical Interference
  • the resonant acoustic transducer coupling circuit 10 of the present invention may be utilized in any application wherein conventional circuits for driving mechanical acoustic transducers, of the type here considered, are used. It is further anticipated that the present invention will find application for driving devices other than transducers, wherever it is necessary to provide a high voltage alternating current signal riding on a direct current biasing voltage. Primary areas of improvement are in the reliability, cost savings, economy and savings in size and weight.
  • the resonant acoustic transducer coupling circuit 10 of the present invention may be readily produced and integrated into existing applications wherein an acoustic transducer is used, it is expected that it will be acceptable in the industry as a substitute for conventional transducer driving circuits. For these and other reasons, it is expected that the utility and industrial applicability of the invention will be both significant in scope and long-lasting in

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Abstract

L'invention concerne un circuit acoustique résonnant de couplage (10) ayant un circuit résonnant (34) avec un condensateur (22) et un inducteur (24) coopérant avec une capacitance (32) de transducteur, la capacitance (32) de transducteur étant la capacitance propre d'un transducteur (28). Un premier commutateur (16) introduit l'énergie pour commencer les oscillations, un second commutateur (18) agit sur le circuit résonnant (34) pour entretenir les oscillations et un troisième commutateur met le circuit résonnant (34) en mode de maintien pour allonger la période du circuit résonnant (34), afin de faire correspondre la fréquence de résonnance électrique du circuit résonnant (34) avec la fréquence de résonnance mécanique du transducteur (28) et ensuite pour arrêter les oscillations en imposant le maintien d'une tension statique élevée sur le transducteur (28) pour que celui-ci se mette en mode réception.
PCT/US1996/019426 1995-12-04 1996-12-04 Commande de transducteur couple resonnant Ceased WO1997023005A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU12816/97A AU1281697A (en) 1995-12-04 1996-12-04 Resonant coupled transducer drive

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US58709795A 1995-12-04 1995-12-04
US08/587,097 1995-12-04

Publications (1)

Publication Number Publication Date
WO1997023005A1 true WO1997023005A1 (fr) 1997-06-26

Family

ID=24348330

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/019426 Ceased WO1997023005A1 (fr) 1995-12-04 1996-12-04 Commande de transducteur couple resonnant

Country Status (2)

Country Link
AU (1) AU1281697A (fr)
WO (1) WO1997023005A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007136920A3 (fr) * 2006-03-21 2008-07-10 Leadis Technology Inc Convertisseur à rendement élevé et à polarisation de l'amplificateur à commutation
US7498880B2 (en) 2006-03-21 2009-03-03 Leadis Technology, Inc. Class L amplifier
US7522433B2 (en) 2006-03-21 2009-04-21 Fairchild Semiconductor Corporation Efficient voltage rail generation
US7619480B2 (en) 2006-03-21 2009-11-17 Fairchild Semiconductor Corporation Distributed class G type amplifier switching method
US7733178B1 (en) 2007-10-24 2010-06-08 Fairchild Semiconductor Corporation High efficiency audio amplifier
US7750732B1 (en) 2007-12-04 2010-07-06 Fairchild Semiconductor Corporation Adaptive rail amplifier (ARA) technology
US8081777B2 (en) 2006-03-21 2011-12-20 Fairchild Semiconductor Corporation Volume-based adaptive biasing
US8179372B1 (en) 2007-10-01 2012-05-15 Integrated Device Technology, Inc. Electronic display with array context-sensitive search (ACS) technology

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4732129A (en) * 1985-04-15 1988-03-22 Nippon Soken, Inc. Control apparatus for electroexpansive actuator enabling variation of stroke
US5057734A (en) * 1988-11-30 1991-10-15 Toyota Jidosha Kabushiki Kaisha Apparatus for driving piezoelectric element for closing and opening valve member
US5204576A (en) * 1990-06-18 1993-04-20 Toyota Jidosha Kabushiki Kaisha Device for driving a piezoelectric element
US5208505A (en) * 1990-06-08 1993-05-04 Toyota Jidosha Kabushiki Kaisha Device for driving a piezoelectric element
US5214340A (en) * 1990-10-09 1993-05-25 Brother Kogyo Kabushiki Kaisha Driver circuit for piezoelectric element, having voltage limiter capable of charging the element with energy from coil after charging switch is off
US5245242A (en) * 1992-04-13 1993-09-14 Rockwell International Corporation Efficiency driver system for piezoelectrics
JPH0614563A (ja) * 1992-06-29 1994-01-21 Nippon Soken Inc 圧電アクチュエータの駆動装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4732129A (en) * 1985-04-15 1988-03-22 Nippon Soken, Inc. Control apparatus for electroexpansive actuator enabling variation of stroke
US5057734A (en) * 1988-11-30 1991-10-15 Toyota Jidosha Kabushiki Kaisha Apparatus for driving piezoelectric element for closing and opening valve member
US5208505A (en) * 1990-06-08 1993-05-04 Toyota Jidosha Kabushiki Kaisha Device for driving a piezoelectric element
US5204576A (en) * 1990-06-18 1993-04-20 Toyota Jidosha Kabushiki Kaisha Device for driving a piezoelectric element
US5214340A (en) * 1990-10-09 1993-05-25 Brother Kogyo Kabushiki Kaisha Driver circuit for piezoelectric element, having voltage limiter capable of charging the element with energy from coil after charging switch is off
US5245242A (en) * 1992-04-13 1993-09-14 Rockwell International Corporation Efficiency driver system for piezoelectrics
JPH0614563A (ja) * 1992-06-29 1994-01-21 Nippon Soken Inc 圧電アクチュエータの駆動装置

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007136920A3 (fr) * 2006-03-21 2008-07-10 Leadis Technology Inc Convertisseur à rendement élevé et à polarisation de l'amplificateur à commutation
US7498880B2 (en) 2006-03-21 2009-03-03 Leadis Technology, Inc. Class L amplifier
US7522433B2 (en) 2006-03-21 2009-04-21 Fairchild Semiconductor Corporation Efficient voltage rail generation
US7619480B2 (en) 2006-03-21 2009-11-17 Fairchild Semiconductor Corporation Distributed class G type amplifier switching method
US7649415B2 (en) 2006-03-21 2010-01-19 Fairchild Semiconductor Corporation Class L amplifier
US8081785B2 (en) 2006-03-21 2011-12-20 Fairchild Semiconductor Corporation High efficiency converter providing switching amplifier bias
US8081777B2 (en) 2006-03-21 2011-12-20 Fairchild Semiconductor Corporation Volume-based adaptive biasing
US8179372B1 (en) 2007-10-01 2012-05-15 Integrated Device Technology, Inc. Electronic display with array context-sensitive search (ACS) technology
US7733178B1 (en) 2007-10-24 2010-06-08 Fairchild Semiconductor Corporation High efficiency audio amplifier
US7750732B1 (en) 2007-12-04 2010-07-06 Fairchild Semiconductor Corporation Adaptive rail amplifier (ARA) technology

Also Published As

Publication number Publication date
AU1281697A (en) 1997-07-14

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