Piezoelectric transducer assembly with phase shifting accoustical parts

Claim 2

A transducer assembly, comprising: a piezoelectric element having a predetermined resonant frequency at which it vibrates, said element being substantially flat and having a node which is substantially free of vibratory motion; structure means mounting said element for substantially unrestricted vibration, said structure means including a pair of flat mounting chips positioned on opposite sides of said flat element and having electrically conductive contact points formed thereon which contact said element along its node and hold said mounting chips and said element in a mutually parallel spaCed apart relationship, said contact points providing electrode means to pick up an electrical signal generated by vibration of said element or to apply an electrical signal to said element to cause vibration thereof; and acoustical port means formed adjacent said element for delaying and thereby shifting into phase acoustical waves generated and sensed by said element which are at said predetermined resonant frequency so that acoustical waves at said predetermined resonant frequency combine in phase at the surface of said element, said acoustical port means being formed adjacent said element by the surfaces of said spaced apart mounting chips and element and being sized as a function of said predetermined resonant frequency.

Claim 3

The invention recited in claim 1, wherein each of said mounting chips is electrically conductive and including electrical leads connected to said mounting chips for connecting said transducer assembly to external electrical circuitry.

Claim 4

The invention recited in claim 1, wherein the node of said element which is substantially free of vibratory motion divides said element into two portions and the portion of said element to one side of said node always vibrates in a direction opposite to the direction of vibration of the portion of said element to the other side of said node, and said acoustical port means are operable to phase shift an acoustical wave at said predetermined resonant frequency as it travels from one side of said node to the other by one-half wave length so that acoustical waves generated or sensed at said resonant frequency reinforce each other.

Claim 5

The invention recited in claim 1, wherein said element vibrates at a resonant frequency in the ultrasonic range.

Claim 6

The invention recited in claim 4, wherein said element is a bender type piezoelectric element.

Claim 7

An ultrasonic transducer assembly, comprising: a piezoelectric element having a predetermined ultrasonic resonant frequency at which it vibrates, said element being substantially flat and having a node which is substantially free of vibratory motion; first structure means defining a resonant cavity which is designed to amplify vibrations at said resonant frequency; second structure means counting said element for substantially unrestricted vibration adjacent said resonant cavity, said second structure means including a pair of electrically conductive flat mounting chips positioned on opposite sides of said flat element and having electrically conductive contact points formed thereon which contact said element along its node and hold said mounting chips and said element in a mutually parallel spaced apart relationship, said contact points providing electrode means to pick up an electrical signal generated on said element or apply an electrical signal thereto; electrical leads connected to said mounting chips for connecting said transducer assembly to external electrical circuitry; and acoustical port means formed adjacent said element for delaying and thereby shifting into phase acoustical waves generated and sensed by said element which are at said predetermined resonant frequency so that acoustical waves at said predetermined resonant frequency combine in phase at the surface of said element, said acoustical port means being formed adjacent said element by the surfaces of said spaced apart mounting chips and element.

Claim 8

An ultrasonic transducer assembly, comprising: a piezoelectric element having a predetermined ultrasonic resonant frequency at which it vibrates, said element being substantially flat and having a node which is substantially free of vibratory motion; first structure means defining a resonant cavity which is designed to amplify vibrations at said resonant frequency; second structure means counting said element for substantially unrestricted vibration adjacent said resonant cavity, said second structure means including a pair of electrically conductive flat mounting chips positioned on opposite sides of said flat element and having electrically conductive contact points formed thereon which contact said element along its node and hold said mounting chips and said element in a mutually parallel spaced apart relationship, said contact points providing electrode means to pick up an electrical signal generated on said element or apply an electrical signal thereto; electrical leads connected to said mounting chips for connecting said transducer assembly to external electrical circuitry; and acoustical port means formed adjacent said element for delaying and thereby shifting into phase acoustical waves generated and sensed by said element which are at said predetermined resonant frequency so that acoustical waves at said predetermined resonant frequency combine in phase at the surface of said element, said acoustical port means being formed adjacent said element by the surfaces of said spaced apart mounting chips and element.

Claim 9

The invention recited in claim 4, wherein said element is a bender type piezoelectric element formed by two transverse expander plates secured together.

Claim 10

The invention recited in claim 7, wherein the node of said element which is substantially free of vibratory motion divides said element into two portions and the portion of said element on one side of said node always vibrates in a direction opposite to the direction of vibration of the portion of said element on the other side of said node, and said acoustical port means are operable to phase shift an acoustical wave at said predetermined resonant frequency as It travels from one side of said node to the other by one-half wave length so that acoustical waves generated or sensed at said resonant frequency reinforce each other.

Claim 11

The invention recited in claim 8, wherein said element is a bender type piezoelectric element formed by two transverse expander plates secured together.

Claim 12

An ultrasonic transducer assembly, comprising: a bender type piezoelectric element having two sides, said element having a predetermined ultrasonic resonant frequency at which it vibrates by bending along its sides, said element having a node which is substantially free from vibratory motion and which divides each side of said element into a center area within said node and an edge area outside of said node so that said center element area always vibrates in a direction opposite to the direction of vibration of said edge element area; structure means mounting said element for substantially unrestricted vibration, said structure means including electrode means positioned to pick up an electrical signal on said element or apply an electrical signal thereto; electrical leads connected to said electrode means for connecting said transducer assembly to external electrical circuitry; and, acoustical port means adjacent each side of said element for delaying and thereby phase shifting acoustical waves generated and sensed by said element, each of said acoustical port means being operable to phase shift an acoustical wave at said predetermined resonant frequency as it travels between said center and edge element areas one-half wave length so that acoustical waves at said predetermined resonant frequency combine in phase on each side of said element.

Claim 13

An ultrasonic transducer assembly, comprising: a bender type piezoelectric element having two sides, said element having a predetermined ultrasonic resonant frequency at which it vibrates by bending along its sides, said element having a node which is substantially free from vibratory motion and which divides each side of said element into a center area within said node and an edge area outside of said node so that said center element area always vibrates in a direction opposite to the direction of vibration of said edge element area; structure means mounting said element for substantially unrestricted vibration, said structure means including electrode means positioned to pick up an electrical signal on said element or apply an electrical signal thereto; electrical leads connected to said electrode means for connecting said transducer assembly to external electrical circuitry; and, acoustical port means adjacent each side of said element for delaying and thereby phase shifting acoustical waves generated and sensed by said element, each of said acoustical port means being operable to phase shift an acoustical wave at said predetermined resonant frequency as it travels between said center and edge element areas one-half wave length so that acoustical waves at said predetermined resonant frequency combine in phase on each side of said element.

Claim 14

the invention recited in claim 10, including second structure means defining a resonant cavity, said resonant cavity being formed adjacent said element and being designed to amplify vibrations at said resonant frequency.

Claim 15

The invention recited in claim 10, wherein said structure means comprises a pair of flat mounting chips positioned on opposite sides of said element and having electrically conductive contact points thereon which contact said element along its node and hold said mounting chips and said element in a mutually parallel spaced apart relationship, said contact means providing said electrode means, said acoustical port means being formed adjacent each side of said element by the surfaces of said spaced apart mounting chips and element.

Claim 16

An ultrasonic transducer assembly, comprising: a piezoelectric element having a predetermined resonant frequency at which it vibrates, said element having a node substantially free from vibratory motion which divides said element into two portions and the portion of said element to one side of said node always vibrating in a direction opposite to the direction of vibration of the portion of said element to the other side of said node; structure means mounting said element for substantially unrestricted vibration, said structure means including electrode means positioned to pick up an electrical signal on said element or apply an electrical signal thereto; and acoustical port means adjacent said element for delaying and thereby phase shifting acoustical waves generated and sensed by said element, said acoustical port means being operable to phase shift an acoustical wave at said predetermined resonant frequency as it travels from one side of said node to the other by one-half wave length so that acoustical waves at said predetermined resonant frequency combine in phase at said element.

Claim 17

An ultrasonic transducer assembly, comprising: a piezoelectric element having a predetermined resonant frequency at which it vibrates, said element having a node substantially free from vibratory motion which divides said element into two portions and the portion of said element to one side of said node always vibrating in a direction opposite to the direction of vibration of the portion of said element to the other side of said node; structure means mounting said element for substantially unrestricted vibration, said structure means including electrode means positioned to pick up an electrical signal on said element or apply an electrical signal thereto; and acoustical port means adjacent said element for delaying and thereby phase shifting acoustical waves generated and sensed by said element, said acoustical port means being operable to phase shift an acoustical wave at said predetermined resonant frequency as it travels from one side of said node to the other by one-half wave length so that acoustical waves at said predetermined resonant frequency combine in phase at said element.