High power acoustical transducer with elastic wave amplification

Claim 3

A method as defined in claim 1 wherein the timing of the discharge of each succeeding element after the first is predetermined to occur in phase sequence such that the elastic wave or any portion thereof produced by each succeeding element is in phase with, and adds to, the elastic wave progressing through the group of elements.

Claim 4

A method as defined in claim 1 wherein the timing of the discharge of each succeeding element after the first is predetermined to occur in phase sequence that the elastic wave or any portion thereof produced by each succeeding element is out of phase with, and subtracts from, the elastic wave progressing through said group of elements.

Claim 5

A method as defined in claim 1 wherein the timing of the discharge in each succeeding element after the first is predetermined to occur in phase sequence such that the elastic wave or any portion thereof produced by one or more of the succeeding elements is in phase with and adds to the elastic wave progressing through said group of elements and the elastic wave produced by one or more of the succeeding elements is out of phase with and subtracts from the elastic wave progressing through said group of elements.

Claim 6

A method as defined in claim 1 wherein each element is comprised of a plurality of piezoelectric subelements acoustically coupled, and wherein subelements of each element are discharged simultaneously, thus providing a longer element for low frequency sonic waves of high energy.

Claim 7

Apparatus for producing an acoustical energy burst of high power ultrasonic soundwaves comprising a stack of piezoelectric elements acoustically coupled, each element comprising a slab of piezoelectric material polarized for operation in the thickness mode in a direction along an axis of said stack, said axis being perpendicular to flat sides of said stacked elements, and a separate conductive film on each side of each slab, high impedance means for simultaneously charging the capacitance of said elements with an electrical charge across each of said elements, and means for discharging each element sequentially through a separate low impedance discharge path in phase relationship with the traveling elastic wave progressing along the sound axis, said discharging means comprising a separate low impedance electronic switch connected to each element, each switch having an anode connected to said conductive film on one side of an element, a cathode connected to said conductive film on the other side of said element, and a control electrode, a capacitor between the anode and control electrode of each switch except the first at one end of said stack, a resistor connected between the control electrode and cathode of each switch except said first one, and means for inducing a voltage pulse between said control electrode and cathode of said first one of said switches, said voltage pulse being of a predetermined polarity to cause said first one of said switches to conduct, thereby discharging the end one of said elements to which said first one of said switches is connected, each of said elements after said end one being polarized to produce an induced voltage pulse of said predetermined polarity in response to an Elastic wave from a preceding element in said stack.

Claim 8

Apparatus for producing an acoustical energy burst of high power ultrasonic soundwaves comprising a stack of piezoelectric elements acoustically coupled, each element comprising a slab of piezoelectric material polarized for operation in the thickness mode in a direction along an axis of said stack, said axis being perpendicular to flat sides of said stacked elements, and a separate conductive film on each side of each slab, high impedance means for simultaneously charging the capacitance of said elements with an electrical charge across each of said elements, and means for discharging each element sequentially through a separate low impedance discharge path in phase relationship with the traveling elastic wave progressing along the sound axis, said discharging means comprising a separate low impedance electronic switch connected to each element, each switch having an anode connected to said conductive film on one side of an element, a cathode connected to said conductive film on the other side of said element, and a control electrode, a capacitor between the anode and control electrode of each switch except the first at one end of said stack, a resistor connected between the control electrode and cathode of each switch except said first one, and means for inducing a voltage pulse between said control electrode and cathode of said first one of said switches, said voltage pulse being of a predetermined polarity to cause said first one of said switches to conduct, thereby discharging the end one of said elements to which said first one of said switches is connected, each of said elements after said end one being polarized to produce an induced voltage pulse of said predetermined polarity in response to an Elastic wave from a preceding element in said stack.

Claim 9

The combination as defined in claim 6 wherein at least one of said low impedance electronic switches is a controlled rectifier.

Claim 10

Apparatus for producing soundwaves comprising: a plurality of piezoelectric elements acoustically coupled, each of said elements being polarized for expansion and contraction along the axis of sound transmission, means for charging said elements simultaneously from a voltage source, means for discharging said charged elements in sequence, each element being discharged through a low impedance path, and means for timing the discharge by detecting the sonic energy induced voltage produced in each element by the elastic wave progressing through said element and triggering a switch to discharge the element in which the induced voltage is detected.

Claim 11

Apparatus for producing soundwaves comprising: a plurality of piezoelectric elements acoustically coupled, each of said elements being polarized for expansion and contraction along the axis of sound transmission, means for charging said elements simultaneously from a voltage source, means for discharging said charged elements in sequence, each element being discharged through a low impedance path, and means for timing the discharge by detecting the sonic energy induced voltage produced in each element by the elastic wave progressing through said element and triggering a switch to discharge the element in which the induced voltage is detected.

Claim 12

Apparatus for producing an acoustical energy burst of high power ultrasonic soundwaves comprising a plurality of piezoelectric elements acoustically coupled, each element comprising a slab of piezoelectric material polarized for operation in the thickness mode in a direction along an axis of said stack, said axis being perpendicular to flat sides of said stacked elements, and a separate conductive film on each side of each slab, high impedance means for simultaneously charging the capacitance of said elements with an electrical charge across each of said elements, and means comprising a controlled rectifier for discharging each element sequentially through a separate low impedance discharge path in phase relationship with the traveling elastic wave progressing along the sound axis, each controlled rectifier having an anode connected directly to a conductive film on one side of a unique one of said slabs, a cathode connected directly to a conductive film on the other side of said unique one of said slabs, and a control electrode connected to receive a triggering signal.

Claim 13

Apparatus for producing an acoustical energy burst of high power ultrasonic soundwaves comprising a plurality of piezoelectric elements acoustically coupled, each element comprising a slab of piezoelectric material polarized for operation in the thickness mode in a direction along an axis of said stack, said axis being perpendicular to flat sides of said stacked elements, and a separate conductive film on each side of each slab, high impedance means for simultaneously charging the capacitance of said elements with an electrical charge across each of said elements, and means comprising a controlled rectifier for discharging each element sequentially through a separate low impedance discharge path in phase relationship with the traveling elastic wave progressing along the sound axis, each controlled rectifier having an anode connected directly to a conductive film on one side of a unique one of said slabs, a cathode connected directly to a conductive film on the other side of said unique one of said slabs, and a control electrode connected to receive a triggering signal.

Claim 14

The combination as defined in claim 9 wherein said means for discharging comprises a capacitor connected between the anode and control electrode of each controlled rectifier except the first at one end, a resistor connected between the control electrode and cathode of each controlled rectifier except said first one, and means for inducing a voltage pulse between said control electrode and cathode of said first one of said controlled rectifier, said voltage pulse being of a predetermined polarity to cause said first one of said controlled rectifiers to conduct, thereby discharging the end one of said elements to which said first one of said controlled rectifiers is connected, each of said elements after said first one being polarized to produce an induced voltage pulse of said predetermined polarity in response to an elastic wave from a preceding element.

Claim 15

The combination of claim 9 wherein said means for discharging comprises a separate resistor between said cathode and control electrode of each silicon controlled rectifier, a separate capacitor having two terminals, one terminal connected to said control electrode of each silicon controlled rectifier, and means for distributing a trigger pulse to second terminal of each of said capacitors in sequence.

Claim 16

The combination of claim 9 wherein each of said elements includes a plurality of piezoelectric subelements, each with separate conductive film on each side, said subelements of an element acoustically coupled with a polarization for operation in said thickness mode along said axis, all of said subelements of an element being electrically connected in parallel for simultaneous charging, and electrically connected in parallel for simultaneous discharging by said means for discharging.

Claim 17

The combination of claim 12 wherein said means for discharging comprises a capacitor connected between the anode and control electrode of each controlled rectifier except the first at one end, a resistor connected between the conTrol electrode and cathode of each controlled rectifier except said first one, and means for inducing a voltage pulse between said control electrode and cathode of said first one of said controlled rectifier, said voltage pulse being of a predetermined polarity to cause said first one of said controlled rectifiers to conduct, thereby discharging the end one of said elements to which said first one of said controlled rectifiers is connected, each of said elements after said first one being polarized to produce an induced voltage pulse of said predetermined polarity in response to an elastic wave from a preceding element.