Method and means for sensing strain with a piezoelectric strain sensing element

Claim 2

Strain sensing apparatus comprising: a first conductor having a prescribed length; a second conductor having a prescribed length compatible with said first conductor substantially surrounding said first conductor in spaced relationship therewith; a layer of strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween so as to be capable of generating an electrical charge when subjected to strain; said electrical charge proportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material; said strain sensing material comprising a material selected from the group consisting of polyethylene, polytetrafluoroethylene, polyvinyl chloride, polyvinyl fluoride, polyvinylidine fluoride, polyethylene terephthalate and polypropylene; and electronic means responsive to said electrical charge connected to said conductors for indicating the occurrence of strain.

Claim 3

The strain sensing apparatus defined in claim 1, wherein said first and second conductors and said strain sensing material are disposed in coaxial relationship.

Claim 4

The strain sensing apparatus defined in claim 1, additionally including an insulating jacket having a prescribed length substantially surrounding said second conductor.

Claim 5

The strain sensing apparatus defined in claim 3, additionally including a protective layer disposed intermediate and extending between said insulating jacket and said second conductor.

Claim 6

The strain sensing apparatus defined in claim 3, additionally including a third conductor having a prescribed length compatible with said second conductor substantially surrounding said second conductor in spaced relationship therewith, an additional layer of strain sensing piezoelectric material disposed intermediate said second and third conductors and extending therebetween, said third conductor and said additional layer of strain sensing piezoelectric material disposed intermediate said second conductor and said insulating jacket.

Claim 7

The strain sensing apparatus defined in claim 1, wherein said electronic means comprises amplifier means connected to said first conductor for amplifying said electric charge and strain indicating means connected to said amplifier means for indicating the occurrence of strain.

Claim 8

A strain sensing apparatus comprising: a first conductor having a prescribed length; a second conductor having a prescribed length compatible with said first conductor substantially surrounding said first conductor in spaced relationship therewith; strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween so as to be capable of generating an electrical charge when subjected to strain; said electrical charge proportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material; an insulating jacket having a prescribed length substantially surrounding said second conductor; and electronic means responsive to said electrical charge connected to said conductors for indicating the occurrence of strain.

Claim 9

A strain sensing apparatus comprising: a first conductor having a prescribed length; a second conductor having a prescribed length compatible with said first conductor substantially surrounding said first conductor in spaced relationship therewith; strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween so as to be capable of generating an electrical charge when subjected to strain; said electrical charge proportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material; an insulating jacket having a prescribed length substantially surrounding said second conductor; and electronic means responsive to said electrical charge connected to said conductors for indicating the occurrence of strain.

Claim 10

The strain sensing apparatus defined in claim 7, additionally including a protective layer disposed intermediate and extending between said insulating jacket and said second conductor.

Claim 11

In combination with an alarm system, a strain sensing piezoelectric device comprising: a first conductor having a prescribed length; a second conductor having a prescribed length compatible with said first conductor substantially surrounding said first conductor in spaced relationship therewith; and strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween so as to be capable of generating an electrical charge when subjected to strain; said electrical charge proportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material.

Claim 12

In combination with an alarm system, a strain sensing piezoelectric device comprising: a first conductor having a prescribed length; a second conductor having a prescribed length compatible with said first conductor substantially surrounding said first conductor in spaced relationship therewith; and strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween so as to be capable of generating an electrical charge when subjected to strain; said electrical charge proportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material.

Claim 13

The alarm system defined in claim 9, wherein said device additionally includes an insulating jacket having a prescribed length substantially surrounding said second conductor.

Claim 14

The alarm system defined in claim 10, wherein said device additionally includes a protective layer disposed intermediate and extending between said insulating jacket and said second conductor.

Claim 15

A piezoelectric device comprising: a piezoelectric sensing element responsive to strain; said piezoelectric sensing element comprising a first conductor having a prescribed length, a second conductor having a prescribed length compatible with said first ocnductor substantially surrounding said first conductor in spaced relationship therewith, a layer of strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween to a prescribed length compatible with said conductors so as to be capable of generating an electrical charge when subjected to strain; said electrical charge porportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material; said strain sensing material comprising material selected from the group consisting of polyethylene, polytetrafluoroethylene, polyvinyl chloride, polyvinyl fluoride, polyvinylidine fluoride, polyethylene terephthalate and polypropylene; and at least one conductor section electrically connected to said piezoelectric sensing element, said conductor section being non-responsive to strain.

Claim 16

A piezoelectric device comprising: a piezoelectric sensing element responsive to strain; said piezoelectric sensing element comprising a first conductor having a prescribed length, a second conductor having a prescribed length compatible with said first ocnductor substantially surrounding said first conductor in spaced relationship therewith, a layer of strain sensing piezoelectric material disposed intermediate and firmly engaging said conductors and extending therebetween to a prescribed length compatible with said conductors so as to be capable of generating an electrical charge when subjected to strain; said electrical charge porportional in amplitude and polarity to the amount of strain transmitted to said strain sensing piezoelectric material; said strain sensing material comprising material selected from the group consisting of polyethylene, polytetrafluoroethylene, polyvinyl chloride, polyvinyl fluoride, polyvinylidine fluoride, polyethylene terephthalate and polypropylene; and at least one conductor section electrically connected to said piezoelectric sensing element, said conductor section being non-responsive to strain.