Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
99 words
A device sensitive to pressure waves characterised by first and second planar sheets (1, 2) of polyvinylidene fluoride supported in spaced apart relationship, each sheet being poled along a direction (33) normal to the major faces (11, 12) (22, 21) of the sheets so as to be more sensitive to pressure waves (W) incident thereon, along said normal direction, than to pressure waves incident thereon along other directions, and by respective faces of the sheets being electrically connected to allow differences of voltage developed across the faces of each sheet to be sensed when pressure waves are incident thereon.
Claim 2
Independent Claim
99 words
A device sensitive to pressure waves characterised by first and second planar sheets (1, 2) of polyvinylidene fluoride supported in spaced apart relationship, each sheet being poled along a direction (33) normal to the major faces (11, 12) (22, 21) of the sheets so as to be more sensitive to pressure waves (W) incident thereon, along said normal direction, than to pressure waves incident thereon along other directions, and by respective faces of the sheets being electrically connected to allow differences of voltage developed across the faces of each sheet to be sensed when pressure waves are incident thereon.
Claim 3
Dependent Claim
64 words
A device according to Claim 1 wherein the faces of each said sheet are provided with-respective-inner and outer electrically conductive sheets (7, 8) (3, 4) in electrically conductive contact with the faces, and the said first and second sheets are poled, in said normal direction, in the same sense (P) relative to the said inner electrically conductive sheets (7, 8) which are electrically connected.
Claim 4
Dependent Claim
29 words
A device according to Claim 2 wherein a sheet (6) of an electrically insulating material (e.g. PTFE) sandwiched between, and bonded to, said electrically conductive inner sheets (7, 8).
Claim 5
Independent Claim
28 words
A device according to any one of Claims 1 to 3 wherein the said sheets of polyvinylidene fluoride have a thickness lying in the range 100µm to 2000µm.
Claim 6
Independent Claim
47 words
A device according to any one of Claims 2 to 4 wherein the said electricaly conductive sheets (7, 8) (3, 4) are of copper and wherein the said major faces (11, 12) (22, 21) of the first and second sheets (1, 2) have coatings of electroless copper.
Claim 7
Dependent Claim
23 words
A device according to Claim 3 or Claim 4 or Claim 5 wherein said electrically conductive inner sheets (7, 8) have different thicknesses.
Claim 8
Independent Claim
30 words
A device according to any preceding Claim including voltage sensing means (9) for sensing differences of voltage developed across the faces of each sheet when pressure waves are incident thereon.