Method for pulse triggering of a piezo-electric sound-transmitting transducer
AssigneeSiemens Aktiengesellschaft
InventorPeter Kleinschmidt
Life of this patent
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Abstract
A piezoelectric ultrasonic transducer is triggered by a predeflection of the transducer in a first direction with a square-wave pulse or a saw-tooth pulse which has a rapidly dropping trailing edge to effect deflection in the opposite direction, with an overshoot. At the maximum point of overshoot, an alternating triggering voltage, preferably in the form of a pulse sequence, is applied to energize and maintain the transducer in resonance oscillation.
Claims8
A method of exciting a piezoelectric transducer into sustained oscillation, comprising the steps of:
- prior to applying periodic voltage pulses having a period .tau.,
- applying a single d.c. voltage pulse to the piezoelectric transducer with a leading edge effective to deflect the transducer to a predetermined deflection in one direction which is approximately equal to the maximum deflection during sustained oscillation and an abrupt trailing edge located within an interval .DELTA.t<.tau./2 effective to deflect the piezoelectric transducer in the opposite direction;
- and then applying the periodic voltage pulses at the time of maximum deflection in the opposite direction to place and maintain the piezoelectric transducer in sustained oscillation.
A method of exciting a piezoelectric transducer into sustained oscillation, comprising the steps of:
- prior to applying periodic voltage pulses having a period .tau., applying a single d.c. saw-tooth voltage pulse to the piezoelectric transducer with a leading edge effective to deflect the transducer to a predetermined deflection in one direction which is approximately equal to 70% of the maximum deflection during sustained oscillation and an abrupt trailing edge located within an interval .DELTA.t<.tau./2 effective to deflect the piezoelectric transducer in the opposite direction;
- and then
- applying the periodic voltage pulses at the time of maximum deflection in the opposite direction to place and maintain the piezoelectric transducer in sustained oscillation.
A method of exciting a piezoelectric transducer into sustained oscillation, comprising the steps of:
- prior to applying periodic voltage pulses having a period .tau.,
- applying a single d.c. voltage pulse to the piezoelectric transducer with an amplitude effective to deflect the transducer to a perdetermined deflection in one direction which is approximately equal to 70% of the maximum deflection during sustained oscillation, a pulse width of approximately .tau./2, and an abrupt trailing edge located within an interval .DELTA.t<.tau./2 effective to deflect the piezoelectric transducer in the opposite direction;
- and then
- applying the periodic voltage pulses at the time of maximum deflection in the opposite direction to place and maintain the piezoelectric transducer in sustained oscillation.
A circuit arrangement comprising:
- a piezoelectric transducer;
- an electronic switch;
- a transformer including a primary winding connected in series with said electronic switch and to an operating potential and a secondary winding connected to said transducer;
- and
- triggering means connected to said switch for applying a triggering signal including a single first input signal pulse having a rising edge, a predetermined amplitude and a rapidly-dropping edge, and a second input signal of a series of following pulses all of substantially the same predetermined amplitude to said electronic switch to trigger the same;
- said first signal pulse having a pulse duration of .theta..apprxeq.Q.sub.m .multidot..tau., where Q.sub.m is the mechanical Q of the transducer and .tau. is the period of the second input signal pulses.
Dependencies are inferred from the claim text.