Pressure sensitive diaphragms with stress null zone oriented bridge patterns

Abstract

.Badd.A pressure responsive device comprising a bridge pattern film bonded to the surface of an electrically non-conductive diaphragm. The bridge including active segment means near the center of the diaphragm in the region thereof where the distance radius ratio is less than about 0.6 and active segment means in the region of the diaphragm where the distance/radius ratio is at least about 0.7..Baddend.

What is claimed is: 1. A pressure responsive device comprising .[.an edge restrained diaphragm having an.].  .Iadd.a diaphragm and means restraining the edge of said diaphragm, said diaphragm having an electrically non-conductive surface to which is bonded an .Iaddend.integral bridge pattern with a plurality of active segments interconnected .[.at.]. .Iadd.by .Iaddend.juncture areas in turn having .Iadd.connected thereto .Iaddend.relatively low resistance conductor segments .[.extending beyond the restrained edge of the diaphragm.].; said juncture areas lying substantially in the radial stress null zone of the diaphragm, with one active segment connected to each juncture area disposed near-center from said radial stress null zone .Iadd.of said diaphragm .Iaddend.and the other active segment connected thereto disposed near-edge from said radial .Iadd.stress .Iaddend.null zone .Iadd.of near diaphragm. .Iaddend. 2. A pressure responsive device according to claim 1, wherein a major part of the active segment disposed .[.outside.]. .Iadd.near-edge .Iaddend.of said radial stress null zone is disposed in the area of and .[.outside.]. .Iadd.near-edge with respect to .Iaddend.the tangential stress null zone 
     
        of said diaphragm. 3. A pressure responsive device according to claim 1, wherein said bridge pattern is composed of a material having a substantial transverse gage factor as well as a substantial parallel gage factor; said near-edge active segment having a substantial part thereof disposed .[.outside of.]. .Iadd.near-edge with respect to .Iaddend.the tangential stress null zone of the diaphragm and extending parallel to the restrained edge thereof, so that the bridge material in substantial part responds to radial stress in relation to its transverse gage factor and in substantial part responds to tangential stress in relation to its parallel gage factor, with such .[.respons.]. .Iadd.responses .Iaddend.augmenting each other. 4. A pressure responsive device according to claim 1, wherein said bridge pattern is composed of a thin, integrally deposited film of electroconductive material. 5. A pressure responsive device according to claim 1, wherein said bridge pattern is composed of a thin, integrally formed film of electroconductive material having a substantial transverse gage factor as well as a substantial parallel gage factor. 6. A pressure responsive device according to claim 5, wherein said film pattern is formed of an electroconductive material having a substantial transverse gage factor, selected from the group consisting of silicon-chrome alloys and metallic resinates. 7. A pressure responsive device according to claim 1, wherein said diaphragm is non-metallic and electrically non-conductive. 8. A pressure responsive device according to claim 7, wherein said diaphragm is fused silica. 9. A pressure responsive device according to claim 1, wherein said diaphragm is metallic and the bridge pattern segments are electrically insulated therefrom. 10. A pressure responsive device comprising a .Iadd.diaphragm, means restraining the edge of said diaphragm, said .Iaddend.diaphragm having an .Iadd.electrically non-conductive surface with an .Iaddend.integral bridge pattern bonded thereto, said .[.pridge.]. .Iadd.bridge .Iaddend.pattern arrangement comprising at least one active segment near the center of the diaphragm, substantially entirely in the region thereof where the distance/radius ratio is from about 0.35 to about 0.6, and at least one other active segment disposed substantially entirely in the region where the distance/radius ratio is at least about 0.7. 11. A pressure responsive device comprising a .Iadd.diaphragm, means restraining the edge of said diaphragm, said .Iaddend.diaphragm having an .Iadd.electrically non-conductive surface with an .Iaddend.integral bridge pattern bonded thereto, said bridge pattern arrangement comprising at least one active segment near the center of the diaphragm substantially entirely in the region thereof where the distance/radius ratio is from about 0.35 to about 0.60, and at least one other active segment disposed near the edge of said diaphragm, substantially entirely in the region where the distance/radius ratio is at least about 0.7, such latter active segment being predominantly in and .[.outside of.]. .Iadd.near-edge with respect to .Iaddend.the region of said diaphragm where the distance/radius ratio is about 0.9. 12. A pressure responsive device according to claim 11, wherein said bridge pattern is composed of an electroconductive material having a substantial transverse gage factor as well as a substantial parallel gage factor. 13. A pressure responsive device according to claim 12, wherein said diaphragm is fused silica. 14. A pressure responsive device according to claim 13, wherein said electroconductive material is an integrally deposited film of semi-conductor material. 15. .[.In a.]. .Iadd.A .Iaddend.pressure responsive device comprising a diaphragm .Iadd.with means restraining the edge thereof and with an electrically non-conductive surface .Iaddend.having bonded thereto a strain sensitive bridge pattern with active segments consisting of an integrally formed electroconductive material having a substantial transverse gage factor as well as a .[.longitudinal.]. .Iadd.parallel .Iaddend.gate factor, said bridge pattern having active segments arranged on said diaphragm to be substantially responsive to strain both perpendicular and parallel to the direction of current flow therein. 16. A pressure responsive device according to claim 15, wherein at least one of said bridge pattern active segments is arranged to provide that at least 20% of the total change of resistance thereof occurs from responsive to strain perpendicular to the direction of current flow. 17. A pressure responsive device according to claim 15, wherein the bridge pattern is comprised to a vacuum deposited film of electroconductive material having a substantial transverse gage factor. 18. A pressure responsive device according to claim 17, wherein said film pattern is formed of an electroconductive material having a substantial transverse gage factor, selected from the group consisting of silicon-chrome alloys and metallic resinates. 19. A pressure responsive device according to claim 15, wherein said diaphragm is a fused silica wafer. 20. .[.In a.]. .Iadd.A .Iaddend.wafer type pressure responsive device comprising .[.an edge clamped diaphragm.]. .Iadd.a diaphragm, means restraining the edge of said diaphragm, the said diaphragm having an electrically non-conductive surface .Iaddend.with an integral film pattern bonded .[.to said diaphragm.]. .Iadd.thereto .Iaddend.edge-to-edge .[.and in essentially quadrant arrangement.]., .Iadd.of the diaphragm, .Iaddend.said film pattern having two diametrically opposite active film segments disposed symmetrically near the center of said diaphragm, and two other diametrically opposite active film segments disposed near the .[.clamped.]. .Iadd.restrained .Iaddend.edge of said diaphragm, said active film segments terminating in juncture areas substantially at the radial stress null zone of the diaphragm, the thickness of all such active film segments being substantially the same and the length/width ratio of each film segment being substantially equal to the length/width ratio of the other active film segments so as to be internally balanced resistively and so as to be internally temperature compensated, and all of such resistor film segments being spaced substantially one from another so as to minimize heating effects. 21. A pressure responsive device according to claim 20, wherein said active film segments are composed of an electroconductive material having a substantial transverse gage factor as well as a parallel gage factor, and the active film segments near the center of the diaphragm extend at least primarily circumferentially thereof to longitudinally receive tangential diaphragm stress and transversely receive radial diaphragm stress, the active film segments situated near the .[.clamped.]. .Iadd.restrained .Iaddend.edge of the diaphragm being arranged in a pattern with substantial components thereof extending both tangentially and radially to be sensitive to both tangential and radial stress. 22. A pressure responsive device according to claim 21, wherein said film pattern is formed of an electroconductive material having a substantial transverse gage factor, selected from the group consisting of silicon-chrome alloys and metallic resinates. 23. A pressure responsive device according to claim 20, wherein said diaphragm is a fused silica wafer. 24. A .[.wafer type.]. pressure responsive assembly, comprising a pressure sensitive diaphragm .Iadd.having an electrically non-conductive surface, .Iaddend.and an electro-conductive film pattern on said .[.diaphragm.]. .Iadd.surface, .Iaddend.with at least one active segment situated near-center of said diaphragm, and at least one active segment situated near-edge of said diaphragm and with relatively low resistance conductor segments integral with and extending from juncture areas .[.as.]. .Iadd.at .Iaddend.the ends of said active segments .[.to the periphery of said diaphragm.]., .Iadd.the .Iaddend.said assembly further comprising a backing plate anularly bonded to said diaphragm .Iadd.only .Iaddend.near the periphery of said diaphragm .[., said backing plate being overlapped by portions of said conductor film segments.].. 25. An assembly according to claim 24, wherein said backing 
     
     
        plate is substantially more rigid than said diaphragm. 26. An assembly according to claim 24, wherein said diaphragm and said backing plate are formed of the same material.  27. An assembly according to claim 24, wherein said diaphragm and said backing plate are of substantially the same thickness and consequently have similar flexural characteristics, the flexure of the backing plate thus augmenting the pressure responsive flexural characteristics of said diaphragm. 28. An assembly according to claim 27, wherein said diaphragm and said backing plate are fused silica. 29. An assembly according to claim 27, wherein said diaphragm and said backing plate are metal. 30. A .[.wafer type.]. pressure responsive assembly, comprising a pressure sensitive diaphragm .Iadd.an electrically non-conductive surface on said diaphragm, .Iaddend.and an integrally formed electroconductive film pattern on said .[.diaphragm.]. .Iadd.surface .Iaddend.with at least one active segment situated near-center of said diaphragm and at least one active segment situated near-edge of said diaphragm, and with relatively low resistance conductor segments integral with and extending from juncture areas at the ends of said active segments to the periphery of said diaphragm, said assembly further comprising a backing plate annularly .Iadd.connected to said diaphragm only near the periphery of said diaphragm, .Iaddend.with said conductor film segments overlapping said backing plate, and conductor output leads connected to said output conductor segments externally of said backing plate at about the peripheral edges of said diaphragm. 31. A .[.wafer type.]. pressure responsive assembly, comprising a pressure sensitive diaphragm, .Iadd.an electrically non-conductive surface on said diaphragm .Iaddend.and an electroconductive film pattern on said .[.diaphragm.]. .Iadd.surface.Iaddend., said film pattern comprising at least one active segment situated near-center of said diaphragm and at least one active segment situated near-edge of said diaphragm, such pattern further comprising relatively low resistance conductor segments integral with and extending from juncture areas at the ends of said active segments to the periphery of said diaphragm, a backing plate bonded to said diaphragm .Iadd.only .Iaddend.near the edge thereof and contacting portions of said conductor film segments, conductor output leads connected to said output conductor segments externally of said backing plate at about the peripheral edges of said diaphragm, and bonding means between the periphery of said diaphragm and the outer portion of said backing plate retaining the same together and encapsulating the connections between said film conductor segments and said output leads. 32. An assembly according to claim 31, wherein said backing plate is substantially more rigid than said diaphragm. 33. An assembly according to claim 31, wherein said diaphragm and said backing plate are formed of the same material. 34. An assembly according to claim 31, wherein said diaphragm and said backing plate are of substantially the same thickness and have similar flexural characteristics, the flexure of the backing plate thus augmenting the pressure responsive flexural characteristics of said diaphragm. 35. An assembly according to claim 34, wherein said diaphragm and said backing plate are fused silica. 36. An assembly according to claim 34, wherein said diaphragm and said backing plate are thin metal. 37. A .[.wafer type.]. pressure responsive assembly, comprising a pressure sensitive diaphragm .Iadd.having an electrically non-conductive surface, .Iaddend.and an electroconductive bridge pattern on said .[.diaphragm.]. .Iadd.surface.Iaddend., said bridge pattern comprising an integral film with at least one active segment situated near-center of said diaphragm and at least one active film segment situated near-edge of said diaphragm, and with relatively low resistance conductor segments integrally extending from about the radial stress null zone of said diaphragm to the periphery thereof, said assembly further comprising a backing plate bonded to said diaphragm and to said conductor segments .Iadd.only .Iaddend.near the outer edge of said diaphragm. 38. A .[.wafer type.]. pressure responsive assembly, comprising a pressure sensitive diaphragm .Iadd.having an electrically non-conductive surface, and an electroconductive bridge pattern on said .[.diaphragm.]. .Iadd.surface.Iaddend., said bridge pattern comprising an integral film with at least one active segment situated near-center of said diaphragm and at least one active film segment situated near-edge of said .[.diaphargm.]. .Iadd.diaphragm.Iaddend., and with relatively low resistance conductor segments integrally extending from about the radial stress null zone of said diaphragm to the periphery thereof, a backing plate bonded to said diaphragm and said conductor segments .Iadd.only .Iaddend.near the outer extent thereof, conductor output leads connected to said output conductor segments externally of said backing plate at about the peripheral edge of said diaphragm, and thermosetting bonding means between the periphery of said diaphragm and the outer portion of said bacing plate retaining the same together and encapsulating the connections between said conductor segments and said output leads. 39. A strain sensitive .[.wafer type.]. pressure transducer assembly, comprising a flexible diaphragm .Iadd.having at least one electrically non-conductive surface, .Iaddend.and an integrally deposited film pattern on .Iadd.said .Iaddend.at least one surface of said diaphragm, said film pattern comprising two oppositely disposed active film segments situated within the radial stress null zone of said diaphragm and two oppositely disposed active film segments situated at least primarily in the area of the tangential stress null zone of said diaphragm, such film pattern further comprising relatively low resistance output conductor film segments connecting with said active film segments in about the said radial stress null zone and extending outwardly therefrom to the periphery of said diaphragm, a backing plate bonded to said diaphragm and said conductor film segments .Iadd.only .Iaddend.near the outer extent thereof, conductor outputs leads connected to said output conductor segments externally of said backing plate at about the peripheral edges of said diaphragm, and thermosetting bonding means between the periphery of said diaphragm and the outer portion of said backing plate retaining the same together and encapsulating the connections between said conductor film segments and said output leads. 40. .[.in a.]. A wafer type pressure responsive device comprising .[.an edge clamped.]. a .Iadd.flexible .Iaddend.diaphragm with .Iadd.means restraining the edge thereof, said diaphragm having an electrically non-conductive surfaces and .Iaddend.an integrally formed film pattern bonded to send .[.diaphragm.]. .Iadd.surface substantially .Iaddend.edge-to-edge .[.and in essentially quadrant arrangement.]. .Iadd.of the diaphragm.Iaddend., said film pattern having at least one active segment disposed inside the radial stress null zone of said diaphragm and at least one active film segment disposed outside the radial stress null zone of said diaphragm, the thickness and length/width ratio of the active film segments being substantially equal, and the active film segments being spaced substantially one from another so as to minimize heating effects. 41. A transducer comprising a circular flexible diaphragm .Iadd.with an electrically non-conductive surface, .Iaddend.means to .[.clamp.]. .Iadd.restrain .Iaddend.said diaphragm near its peripheral edge, a bridge pattern including two pairs of active resistor segments bonded to said .[.diaphragm.]. .Iadd.surface.Iaddend., the resistor segments of a first pair being positioned on the .Iadd.said .Iaddend.surface of said diaphragm near the .[.clamped.]. .Iadd.restrained .Iaddend.edge .[.thereof.]. .Iadd.of said diaphragm.Iaddend., the net stress in the diaphragm at said first pair of resistor segments upon imposition of a uniform load being of net positive value, said first pair of resistor segments being symmetrically and oppositely arranged on the diaphragm, the resistor segments of the second pair of segments being positioned adjacent to the center of the diaphragm, the net stress in the diaphragm in the area of said second pair of resistor segments being of negative value, said second pair of resistor segments also being symmetrically and oppositely arranged on said diaphragm, said bridge pattern further comprising junction areas in interconnecting adjacent resistor segment ends, said juncture areas at least in part being in a region of the diaphragm where the factor .Iadd.r/a minus the factor .Iaddend. ##EQU24## substantially equals zero, .Iadd."r/a" being the distance "r" of said region from the center of the diaphragm divided by the radius "a" of the diaphragm from the center to the restrained portion thereof, and .Iaddend."m" being the reciprocal of the Poisson's ratio of the diaphragm 
     
     
        material. .Iadd. 42.  A pressure responsive device comprising a pressure sensitive diaphragm with means restraining the edge thereof, said diaphragm having an electrically non-conductive surface and a bridge pattern on said surface, said bridge pattern comprising at least two active segments terminating substantially in the radial stress null zone of the diaphragm, with one such active segment disposed near-center from the radial stress null zone of the diaphragm and the other such active segment disposed near-edge from the radial stress null zone of the diaphragm. .Iaddend..Iadd. 43. A pressure responsive device comprising a pressure sensitive diaphragm with means restraining the edge thereof, said diaphragm having an electrically non-conductive surface and an integral bridge pattern on said surface, said bridge pattern comprising at least two active segments interconnected at a juncture area lying substantially in the radial stress null zone of the diaphragm, with one such active segment connected to said juncture area disposed near-center from the radial stress null zone of the diaphragm and the other such active segment connected to said juncture area disposed near-edge from the radial stress null zone of the diaphragm. .Iaddend..Iadd. 44. A pressure responsive transducer comprising a flexible diaphragm with means restraining the edge thereof and with an electrically non-conductive surface having bonded thereon a bridge pattern comprising a plurality of active segments terminating at juncture areas, said pattern being arranged so that each of said juncture areas lies substantially in the radial stress null zone of the diaphragm, with one such active segment being disposed near-center from the radial stress null zone of the diaphragm and the other active segment being disposed near-edge from the radial stress null zone, of the diaphragm such near-edge active segment being disposed with a major part thereof in the area of and near-edge with respect to the tangential stress null zone of said diaphragm. .Iaddend..Iadd. 45. A pressure responsive transducer comprising a flexible diaphragm with means restraining the edge thereof and with an electrically non-conductive surface having thereon a bonded bridge pattern in the form of an integral film, said bridge pattern comprising a plurality of active segments interconnected at juncture areas, said pattern being arranged so that each of said juncture areas lies substantially in the radial stress null zone of the diaphragm, with one active segment connected to each such juncture areas being disposed near-center from the radial stress null zone of the diaphragm and the other active segment connected to each such juncture area being disposed near-edge from the radial stress null zone of the diaphragm, such near-edge active segment being disposed with a major part thereof in the area of and near-edge with respect to the tangential stress null zone of said diaphragm. .Iaddend. .Iadd. 46. A pressure responsive device comprising a diaphragm with means restraining the edge thereof and with an electrically non-conductive surface having bonded thereto a bridge pattern comprising .Badd.a bridge arm including .Baddend..Iadd.at least one active segment near the center of the diaphragm and disposed substantially entirely in the region thereof where the distance/radius ratio is less than about 0.6, and further comprising at least one other .Iaddend..Badd.bridge arm including another .Baddend..Iadd.active segment disposed substantially entirely in the region of the diaphragm where the distance/radius ratio is at least about 0.7.Iaddend..Badd., each of said active segments being connected to relatively low resistance juncture areas bonded to said surface and at least in part disposed in the region of said diaphragm where the distance/radius ratio is from about 0.6 to about 0.7. .Baddend. .Iadd. 47. A pressure responsive device comprising a diaphragm with means restraining the edge thereof and with an electrically non-conductive surface having an integral bridge pattern bonded thereto, said bridge pattern arrangement comprising at least one active segment near the center of the diaphragm substantially entirely in the region thereof where the distance/radius ratio is less than about 0.6, and at least one other active segment disposed substantially entirely in the region of the diaphragm where the distance/radius ratio is at least about 0.7. .Iaddend..Iadd. 48. A pressure sensitive transducer comprising a circular flexible diaphragm with means restraining the edge thereof and with an electrically non-conductive surface, a bridge pattern including a plurality of active resistor segments bonded to said surface, of which a first resistor segment is positioned on the said surface near the edge of said diaphragm, the net stress in the diaphragm in the area of said first resistor segment upon imposition of a uniform load being of net positive value, a second resistor segment positioned on said surface adjacent to the center of the diaphragm, the net stress in the diaphragm in the area of said second resistor segment being of negative value upon such uniform loading, said bridge pattern further comprising a juncture area interconnecting adjacent ends of said first and second resistor segments, said juncture area at least in part being in a region of the diaphragm where the factor r/a minus the factor ##EQU25## substantially equals zero, where "r/a" is the distance "r" of said region from the center of the diaphragm divided by the radius "a" of the diaphragm, and "m" is the reciprocal of the Poisson's ratio of the 
     
     
        diaphragm material. .Iaddend..Iadd. 49.  A flexible circular diaphragm adapted to act as a transduction means in a transducer, comprising a circular flexible diaphragm rigidly restrained at its peripheral edge only, an electrically non-conductive surface on said diaphragm, and a film pattern bonded to said surface, said film pattern including at least a pair of active segments, one of said active segments being positioned entirely in and having terminal ends positioned in the area of said diaphragm at a radial distance equivalent to an r/a value substantially greater than about 0.6, and another of said active elements being positioned entirely in and having terminal ends positioned in the area of the diaphragm at a radial distance equivalent to an r/a value substantially less than about 0.6, the said active segments being separated from each other by a radial distance difference extending a substantial distance both sides of a radial distance equivalent to an r/a value of about 0.6 where "a" is the radius of said circular diaphragm and "r" is the above stated radial distance, and relatively low electrical resistance juncture films bonded to such diaphragm surface, one of said juncture films being connected to one of the terminal ends of each of the active segments of said pair. .Iaddend..Iadd. 50. A transduction element for a transducer comprising a circular diaphragm rigidly restrained at its peripheral edge only, means to apply a load to said diaphragm to deflect said diaphragm, an electrically non-conductive surface on said diaphragm, and a film pattern bonded to said surface, said pattern including at least a pair of active segments, one of said active segments being positioned entirely in the area of said diaphragm at a radial distance equivalent to an r/a value greater than about 0.6, and the other of said active segments being positioned entirely in the area of said diaphragm at a radial distance equivalent to an r/a value substantially less than about 0.6, with one of the said active segments being separated from the other of said active segments by a substantial radial distance difference, a plurality of juncture elements bonded to said diaphragm and interconnecting said active segments, with each of said juncture elements extending a substantial distance across a radial distance equiavalent to an r/a value of about 0.6 and a substantial distance to either side of said last named radial distance, said juncture elements having a relatively low electrical resistance as compared with the electrical resistance of said active segments, and electrical connectors connected to each of said juncture elements, where "a" is a radius of the diaphragm and "r" is said radial distances. .Iaddend..Iadd. 51. A tranduction element for a transducer comprising a flexible circular diaphragm rigidly restrained at its peripheral edge only, an electrically non-conductive surface on said diaphragm, and a film pattern bonded to said surface, said pattern including at least two pairs of active segments, the active segments of one of said pairs being separated from each other and being positioned entirely in the area of said diaphragm at a radial distance equivalent to an r/a value substantially greater than about 0.6, said active segments terminating at a radial distance equivalent to an r/a value substantially greater than about 0.6, and the active segments of the other of said pairs being separated from each other and being positioned entirely in the area of the diaphragm at a radial distance substantially less than that equivalent to an r/a value of about 0.6, said last named active segments terminating at a radial distance equivalent to an r/a value of substantially less than about 0.6, the said active segments of one of said pairs being separated from the active segments of the other of said pairs, and the ends of the segments of one of said pairs being separated from the ends of the other active segments of the other of said pairs by a radial distance difference extending a substantial radial distance both sides of a radial distance equivalent to an r/a value of about 0.6, where "a" is the radius of the diaphragm and "r" is the above radial distances, each such end of said active segments of one of said pairs being connected to an associated terminal end of an active segment of the other of said pairs by a junction film bonded to said diaphragm, each said junction film having a relatively low electrical resistance compared to the resistance of said active segments and electrically connecting said active segments in a bridge configuration, with said active segments being otherwise electrically insulated from each other except at such junctions.