Pennwalt Corporation

Philip E Bloomfield

Walter Kulischenko

Richard A Ferren

Seymour Preis

Dean H Wickwire

Harry Shpuntoff

Apparatus and processes for preparing polymeric piezoelectric films of one or more layers or tubular products having a central wire core by drawing a suitable polymeric blank through either a flat or a conically tapered drawing die having associated electrical field producing means, to simultanelusly stretch and pole the polymeric material within the die chamber.

Die drawing process and apparatus for piezoelectric polymer films and

A nonfibrous, unoriented sheet of a copolymer resin of about 65 to 85 mol percent of vinylidene fluoride and from 15 to about 35 mol percent of at least one other copolymerizable substituted monoolefinic monomer, said sheet having improved and uniform piezoelectric properties for hydrophonic use, and the process for preparing said sheet with improved piezoelectric and dielectric breakdown strength properties wherein it is heated for at least about 20 minutes within the temperature range of above the crystalline melting temperature and below a defined temperature, cooled to below the Curie temperature and then electrically poled, are disclosed herein.

Process of preparing nonfibrous, piezoelectric polymer sheet of improved

Strips are prepared from a stack of two superposed metallized polymer films, each film having piezoelectric properties. The stack is coated with a conventional plastically deformable wax impression material to provide the normal visual indication of bite deflection and premature teeth engagement. The stack of metallized polymer films provides means through which sliding bite forces exerted during occlusal analysis may be monitored and recorded.

Piezoelectric polymeric film discriminating bite force occlusal indicator

Weight sensing apparatus, typically a personal scale, employs a thin film of piezoelectric polymeric material as the transducing component for converting mechanical pressure in the form of applied weight to voltages which are digitally displayed in pounds.

Weight sensing apparatus employing polymeric piezoelectric film

Dental impression strips prepared from metallized polymer film having piezoelectric properties are coated with a conventional plastically deformable wax impression material to provide the normal visual indication of bite deflection and premature teeth engagement. The metallized polymer film provides means through which force exerted during occlusal analysis may be monitored and recorded. By coating the metallized polymer film with a non-permanently deformable and reusable plastic, the monitoring and recording may readily be demonstrated to the dentist and patient.

Piezoelectric polymeric film occlusal force indicator

In a vehicle steering system for automobiles, for example, a steering column is provided with a rotatable flexible shaft at the end thereof for improving the ability of the column to absorb energy in a crash situation. The flexible shaft has at least one strip of a plastic material, preferably polyvinylidene fluoride film made piezoelectric by known methods, secured to an outermost winding of the flexible shaft. Turning the steering wheel will torsionally deflect the flexible shaft which causes the piezoelectric strips to generate millivoltages thereacross. A deteriorating flexible shaft will deflect more under torsional stress than a comparable newer flexible shaft and the piezoelectric strip or strips secured to the deteriorating shaft will consequently produce higher millivoltages. These millivoltages are amplified and fed to indicating means for indicating the degree of safeness of the flexible shaft.

Safeness indicator for flexible shafts used in automotive steering

A plastic material, preferably polyvinylidene fluoride (PVDF) film, made highly piezoelectric by known methods, is placed in a sensor unit structure wherein pressure is exerted against the piezoelectric film by means of rotation of the steering wheel of the boat or vehicle to thereby cause the piezoelectric film to generate electric signals which are used in controlling the rpm of a low-inertia, instantaneously reversible steering power assist motor. The rpm of the motor is substantially proportional to the input electric signals, which, in turn, are determined by, and responsive to, the degrees of rotation and speed of rotation of the steering wheel. The direction of rotation of the steering wheel determines the direction of steering assist, i.e., to the left or right. Available torque of the motor however is substantially inversely proportional to rpm of the engine propelling the boat or vehicle.

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Bala Cynwyd, PA, United States of America

Philip E Bloomfield