Did You Know...
...that the x-ray was discovered purely by accident? When German physicist Wilhelm Konrad von Roentgen was experimenting with cathode rays in 1895, he put an activated Crookes tube in a book and went out to lunch. When he returned, he discovered that a key that had also been placed in the book showed up as an image on the developed film!
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US Patent 5254296 - Method to double the piezo-and pyroelectric of polyvinylidine fluoride (PVDF) films
US Patent Issued on October 19, 1993
Estimated Patent Expiration Date:
November 13, 2011Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Estimated Patent Expiration Date:
November 13, 2011Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.AbstractPolyvinylidene fluoride (PVDF) films and co-polymers thereof possess the highest values of piezoelectric and pyroelectric constants of any known polymer. These films, up to present, have been first subjected to stretching and then to a high electric field (or corona charge) at an elevated temperature to provide a maximum piezoelectric constants (d31) of about 30-35 pC/N and a maximum pyroelectric constants (p) of about 3.5 nC/cm2 K. It has now been found that the piezoelectric constant d31 and pyroelectric constant p of these films can be increased up to about 60 pC/N and 6 nC/cm2 K respectively when they are subjected to simultaneously stretching and corona poling with a poling field Ep =0.55MV/cm, a stretching ratio S.R.=4.5X and a poling temperature Tp =80° C. | InventorAssigneeApplicationNo. 791275 filed on 11/13/1991US Classes:264/435, Molecular aligning or molecular orientating (e.g., poling, etc.)264/288.4, Stretching by applying tension264/483, Plasma (e.g., corona, glow discharge, etc.)425/174.8EElectro-staticField of Search264/288.4, Stretching by applying tension425/174.8EElectro-staticExaminersPrimary: Thurlow, JefferyAttorney, Agent or FirmUS Patent References4265841, Method for production of composite piezoelectric materialIssued on: 05/05/1981 Inventor: Fujimori , et al.4308370, Piezoelectric and pyroelectric polymer film and process for preparing same Issued on: 12/29/1981 Inventor: Fukada , et al.4345359, Process for manufacturing a piezoelectric transducer made from a polymer material Issued on: 08/24/1982 Inventor: Micheron4403382, Process for manufacturing electromechanical transducers using at least one polymer film Issued on: 09/13/1983 Inventor: Facoetti , et al.4427609, Process for producing piezoelectric polymer films Issued on: 01/24/1984 Inventor: Broussoux , et al.4481158, Extrusion of films of vinylidene fluoride polymers Issued on: 11/06/1984 Inventor: Georlette , et al.4557880, Piezoelectric and pyroelectric film Issued on: 12/10/1985 Inventor: Pantelis4668449, Articles comprising stabilized piezoelectric vinylidene fluoride polymers Issued on: 05/26/1987 Inventor: Soni , et al.4800048Die drawing process and apparatus for piezoelectric polymer films and tubes Issued on: 01/24/1989 Inventor: Bloomfield , et al. Foreign Patent References
International ClassB29C 035/00Foreign Application Priority Data1990-12-11 CA |
