Abstract: A method of making a polymeric piezoelectric acoustic transducer tape that is thin enough to be stored in roll form and adapted for placement on a lengthy supportive surface is disclosed. A piezoelectric film is heat-formed to provide a plurality of repetitively curved portions therein, conductive electrodes are applied on opposite surfaces of the curved film, a long, narrow layer of flexible, resilient material is adhered to one surface of the curved film and one or more adhesive portions are applied to the surface of the resilient material.

Abstract: A radiation sensitive piezoelectric copy method and medium for producing positive or negative latent electrostatic charge patterns. In a first embodiment the copy medium includes a poled, radiation transmissive piezoelectric insulative layer, an electrically conductive layer less compliant than the piezoelectric layer, and a photoconductive layer interposed between and electrically connected with the piezoelectric and electrically conductive layers. A second embodiment is similar to the first embodiment except it does not contain an electrically conductive layer. A third embodiment is similar to the second embodiment except that an electrically conductive layer is juxtaposed with and electrically connected to the piezoelectric layer.

Abstract: A temperature sensor and method for producing a remanent electrostatic image of a thermal gradient existing on the surface of an object are disclosed. The sensor includes a layer of poled, pyroelectric material that is employed as a medium on which the thermal gradient image is electrostatically formed, with such pyroelectric layer coated on one side with a thermally and electrically conductive layer. The sensor is positioned for a time with its conductive layer in surface-to-surface contact with the object to permit the temperature of the pyroelectric layer to conform to the thermal gradient of the surface of the object contacted by the sensor. Subsequently, both planar surfaces of the pyroelectric layer are electrically neutralized and the sensor is then removed from the object. As the pyroelectric layer returns to the ambient temperature, an electrostatic image representative of the thermal gradient of the object is formed on the uncoated surface of the pyroelectric layer.

Abstract: A strain sensor and a method for producing a remanent electrostatic image of the strain gradient existing on the surface of an object are disclosed. The sensor includes a layer of poled, piezoelectric material that is employed as a medium on which the strain gradient image is electrostatically formed. The piezoelectric layer is coated on one side with an electrically conductive layer, and the sensor is adapted to be positioned with the conductive layer in surface-to-surface contact with the object. Thereupon, a stress is applied to the object to place it in a condition of strain whereby the object is dimensionally changed or deformed. Both layers of the sensor are highly compliant to permit the sensor to be bent from its normal configuration to conform to the surface stress of the object without significantly affecting the strain of the object. Next, the surfaces of the piezoelectric layer are neutralized and the stress on the sensor is then relaxed.

Abstract: An apparatus and method for rapidly and continuously poling a film of polymeric material exhibiting at least one of pyroelectric and piezoelectric characteristics to yield a poled film having a high coefficient of at least one of pyroelectric and piezoelectric properties, and a high degree of uniformity of polarization throughout its thickness. The method of the present invention includes applying a plurality of time-spaced electric field pulses across a portion of the film. The apparatus of the present invention includes a drive for advancing the film and a pair of electrodes that establish an electric field across the film. A hot poling roller serves as a high voltage electrode and a grounded roller contacts a conductive layer coated on the other side of the film. A voltage source and a switch coact to apply a plurality of time-spaced electric field pulses between the two electrodes.

Abstract: An apparatus and method for continuously poling a film of material exhibiting pyroelectric and/or piezoelectric characteristics are disclosed. The apparatus includes a drive for advancing the film, a hot poling roller, a cold fixing roller, and a pair of electrodes that establish an electric field across the film while it is heated by the hot roller. In a first embodiment, one side of the film is coated with a conductive layer that is electrically grounded to serve as a ground electrode and the poling roller serves as a high voltage electrode for establishing the electrical field across the film. In a second embodiment, the poling roller is electrically grounded and a plurality of corona charging devices are employed as the high voltage electrode. In both embodiments, the poling roller is separated from direct physical contact with the film by a resistive layer in order to avoid serious damage to the film due to electrical arcing that can occur through a defective or thinner than normal area of the film.

Abstract: A two sensitivity level detector for sensing motion of an object on which the detector is placed. The detector includes a sensing unit that responds to movement of the object by supplying electrical current to sensing circuitry adapted to provide an indication of movement upon receipt of such current. The housing of the detector is formed with at least one exterior planar surface and at least one spherical surface so that detector movement in response to movement of the object is dependent upon whether the detector has its planar or spherical surface in contact with the object.

Abstract: A piezoelectric polymer transducer for converting mechanical energy into electrical energy includes a transducing means formed of a polymeric piezoelectric layer of material that is connected at its ends to a support means in such fashion that it can readily vibrate. The piezoelectric layer is coated on at least an outer portion of each of its planar surfaces with conductive electrodes and a weight is attached to the piezoelectric layer to act as an inertial mass to accentuate bending of such layer in response to movement of the support means.

Abstract: A motion detector that includes one or more sensing units fastened by at least one end to an interior portion of a housing. The sensing units are flexible so that they readily bend in response to movement of the detector, and a small weight is mounted on each sensing unit to accentuate such bending. Each sensing unit includes a thin strip of poled, polymeric piezoelectric material having planar surfaces. Conductive electrodes are carried on only the portions of such surfaces adjacent the end (ends) of the sensing unit fastened to the housing. An electronic circuit is connected across the conductive electrodes for sensing electrostatic charges that are produced by the bending of the piezoelectric material of the sensing units and for providing a signal indication of such bending.

Abstract: A sensing device is provided for the detection of electromagnetic radiation through the use of a large area pyroelectric/piezoelectric sensing medium. The detection operation of the sensing device is constructed to ignore spurious detection indications due to bending or compression of the sensing medium. In a preferred embodiment the sensing device is formed from a two housing construction that includes outer and inner housings. The outer housing of the device includes an infrared transmissive window at one end. To substantially physically isolate the two housings from one another, the inner housing of the device is supported inside the outer housing by means of support members protruding through the opposite end of the outer housing. The sensing medium is disposed in one end of the inner housing and is protected by the outer housing from bending or compressive stress.

Abstract: Processes for attracting charged and non-charged particles from a fluid by means of a pyroelectric filtering medium.

Abstract: A strain sensor and a method for producing a remanent electrostatic image of the strain gradient existing on the surface of an object are disclosed. The sensor includes a layer of poled, piezoelectric material that is employed as a medium on which the strain gradient image is electrostatically formed. The piezoelectric layer is coated on one side with an electrically conductive layer, and the sensor is adapted to be positioned with the conductive layer in surface-to-surface contact with the object. Thereupon, a stress is applied to the object to place it in a condition of strain whereby the object is dimensionally changed or deformed. Both layers of the sensor are highly compliant to permit the sensor to be bent from its normal configuration to conform to the surface stress of the object without significantly affecting the strain of the object. Next, the surfaces of the piezoelectric layer are neutralized and the stress on the sensor is then relaxed.

Abstract: A temperature compensated sensing device for sensing a particular condition includes first and second conductive layers in surface-to-surface contact with and separated by a layer of poled, pyroelectric material. In a preferred embodiment, the second conductive layer is electrically grounded and the first conductive layer is etched to define two interdigitated, electrically unconnected sets of conductive portions. The sets of conductive portions are heated when exposed to the condition desired to be detected and, in turn, heat areas of the pyroelectric layer. As a result, electrostatic charges are developed on the heated pyroelectric areas and appear as voltage potentials on the heated conductive portions. Electronic circuitry having a differential amplifier is electrically connected to the conductive portions for sensing the voltage potentials thereon and for triggering an alarm when certain voltage potentials exist.

Abstract: An electromagnetic radiation sensitive copy medium and method for producing positive or negative copies electrostatically. In a first embodiment the copy medium includes a poled, radiation transmissive, pyroelectric insulative layer, an electrically conductive layer, and a photoconductive layer interposed between and electrically connected with the insulative and conductive layers. A second embodiment includes two insulative layers, a photoconductive layer that is interposed between the insulative layers, and an electrically conductive layer that is juxtaposed with one of the insulative layers. A third embodiment is basically similar to the first embodiment except that it includes a plurality of photoconductive layers, each being sensitive to a single, but different, color of light.

Abstract: A sensing medium having two sensing units each formed of a layer of poled electret material that is coated on each planar surface with an electrically conductive plate, such sensing units being separated from one another by a thermal insulating layer.

Abstract: A sensing device that may be employed as a thermal or stress sensor includes in one embodiment a pair of poled electret layers as sensing mediums for detecting variations in the ambient temperature of the sensor. The electret layers of such embodiment have pyroelectric and piezoelectric properties, but only pyroelectrically produced electrical signals are used for sensing and piezoelectrically produced signals due to bending are effectively negated. In another embodiment, the electret layers are used as stress sensors whereby piezoelectrically produced electrical signals are sensed and pyroelectric signals are operatively canceled.

Abstract: A directional radiation detector having a pyroelectric sensing medium for responding to radiation and a directional screen formed of a panel with a plurality of axial passages that restrict the radiation viewing angle of the detector.

Abstract: A method is disclosed for copying a graphic representation using a uniformly poled pyroelectric material.The uniformly poled pyroelectric material is selectively heated to form a differential charge pattern on the material. The differentially charged material can be used with charged toner particles to form a copy of the graphic representation using techniques well known in the art.