Abstract: An electrostatic evacuated insulating sheet comprises two permanently charged electret repulsion layers (18 and 28) laminated to two respective insulating layers (16 and 26), which are in turn laminated to two impermeable metallic compensation layers (14 and 24). The foregoing laminate is then covered by two protective layers (12 and 22). The repulsion layers (18 and 28) are sufficiently charged with monopolar electric charges so that, by Coulomb force, a small (1 to 20 micron) evacuated space is established and maintained between the repulsion layers. This space is sufficient to stop all heat transfer through the sheet by convection or conduction. The resulting vacuum insulated sheet is very thin (1.2 mm to 2.9 mm) and flexible. It provides an greatly improved insulating performance over any previous flexible sheet insulation, equivalent to at least 170 mm of polystyrene foam.

Abstract: The invention relates to the obtaining of a structure generating non-linear electrooptical effects, the effects being due to molecules or inter-molecular groupings possessing a non-linear susceptibility and the orientation of the molecules or groupings being induced by an applied electric field. According to the invention, the orientation of the molecules or inter-molecular groupings (5) is obtained by of a dielectric having a permanent polarisation such as an electret (6).

Abstract: A film electret and an electret filter that contain a polar high-molecular weight compound and that provides a TSDC curve having a homocharge peak temperature of at least 95.degree. C. and a heterocharge peak temperature of at least 80.degree. C.

Abstract: A method and circuit for measuring direct and high duty factor current in a conductor (1) with minimal interference with the operation of a monitored circuit. Current flow in the conductor is magnetically sensed with a transformer T1 having a primary winding connected electrically in series with the conductor (1). The transformer T1 is driven into saturation during a first time interval and brought out of saturation during a second time interval. After the transformer T1 is brought out of saturation, an output signal is provided which is proportional to the flow of current in the conductor (1).

Abstract: In one embodiment this invention provides vinylidene cyanide copolymers with alternating monomeric units as illustrated by the following structure: ##STR1## An invention vinylidene cyanide copolymer in the form of an electret film exhibits a high level of longitudinal piezoelectric effect, and has excellent processability properties. An electret film which has an external electric field-induced noncentrosymmetric dipolar molecular orientation exhibits second order nonlinear optical susceptibility under light propagation conditions.

Abstract: In one embodiment this invention provides vinylidene copolymers with alternating monomeric units as illustrated by the following structure: ##STR1## An invention vinylidene copolymer in the form of an electret film exhibits a high level of longitudinal piezoelectric effect, and has excellent processability and thermal stability properties.

Abstract: This invention relates to an electret material having thermal stability and capable having high trapped charge quantity and stably existing for a long period of time and a process for preparing the electret material. The electret material is characterized in that it comprises 100 parts by weight of polypropylene, 0.01 to 2 parts by weight of a least one stabilizer selected from among hindered amine, nitrogen-containing hindered phenol, and metal-containing hindered phenol stabilizer and that at least part of the propylene has such a molecular weight distribution that the M(w)/M(n) ratio wherein M(w) is a weight-average molecular weight is 5.5 or less. The electret material can be widely used for various applications and, e.g., is best suited for use in, e.g., various filter materials, wiper materials, absorption materials, masking materials, and dust-proof materials.

Abstract: A self-regulated system and method for controllably administering a therapeutic agent to a patient is disclosed. A therapeutic agent is driven by unidirectional electrostatic diffusion across a rate-controlling electret membrane. The diffused therapeutic agent is then delivered to a patient. The preparation of the electret membrane and therapeutic agent delivery apparatus are also disclosed.

Abstract: An electret transducer including a pair of spaced electrodes, one electrode being connected to a preamplifier input, an insulator on the outer surface of the electrode connected to the preamplifier input, and a conductive layer on the other side of the insulator, whereby the conductive layer can be used to shield the electrode to reduce stray capacitance between it and other components of the transducer by connecting the conductive shield to the output of the preamplifier circuit for the transducer. Also disclosd is the use of a silicon backplate with an integrated circuit formed therein, an insulator layer thereon, a conductive layer thereon, and an electret layer thereon, the conductive layer being grounded during poling of the electret to protect the integrated circuit from damage.

Abstract: This invention provides an electroacoustic transducer and a method of making it. The transducer according to the invention comprises a substrate of a semiconductor material with a recessed portion. A membrane is stretched across the recessed portion, which membrane is set in vibration in response to an input signal comprising audio and/or ultrasonorous frequencies. A pair of electrodes is provided, which form a capacitor, and between which an electric field is present. The electrodes are so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals. A layer of an electrically insulating material functions as a carrier for an electric charge to provide an auxiliary electric field between the electrodes.

Abstract: An electret fiber sheet has polarized charges on its surface and preferably has charges in ordered orientation across it. The polarized charges are present in an amount of at least 7.times.10.sup.-11 C/cm.sup.2. Such sheets are formed to have a dust collecting efficiency. Sheets having an amount of polarized charge even as high as this are nevertheless stable when they have a maximum orientation energy of depolarization of at least 0.2 eV.Such an electret sheet can be obtained by a process comprising placing a fiber sheet between a non-contact type voltage-application electrode and an earth electrode confronting each other and supplying electricity (voltage>3 kV; current density>1.times.10.sup.-6 mA/cm.sup.2) between the electrodes, provided that the fiber sheet has a weight less than 80 g/m.sup.2 and a covering factor at least 60%.

Abstract: A self-regulated system and method for controllably administering a therapeutic agent to a patient is disclosed. A therapeutic agent is driven by unidirectional electrostatic diffusion across a rate-controlling electret membrane. The diffused therapeutic agent is then delivered to a patient. The preparation of the electret membrane and therapeutic agent delivery apparatus are also disclosed.

Abstract: A drive circuit of a two-laminated electrostriction element, wherein a common junction of two sheets of electric distortion elements is connected to one of the driving power source through a first switching means, and the other terminal of the one electrostriction element is connected to the other of said driving power source, with the other terminal of the other electrostriction element being connected to a second switching means, thereby to rotate the other electrostriction element by the voltage charged in the one electrostriction element.

Abstract: A holder for an electret microphone of the type having a front acoustic aperture and peripheral acoustic apertures is made of insulating material and includes a first sleeve portion of a diameter to receive the microphone snugly and a second sleeve portion of larger diameter. An internal stop limits the extent to which the microphone can be inserted such that the rear portion of the microphone projects into the second sleeve portion. Through holes in the second sleeve portion provide an acoustic passage to the peripheral acoustic apertures. The internal stop is in one embodiment formed by an apertured web. In another embodiment an internal shoulder forms the stop but in that embodiment too an apertured web is provided. A concentric small cylinder extends from the web in that case and terminates short of the shoulder. In either embodiment, a rectangular plate is molded with the sleeves and this forms the cover of a microphone enclosure.

Abstract: An electret comprising an inherently charged material is provided. The material comprises phyllosilicate minerals and has external neutralizing ions removed therefrom or external ions added thereto. The electret is manufactured by either removing external ions from or adding external ions to a surface thereof. In a preferred embodiment, the electret is fabricated by placing the material between a pair of electrodes and immersing the material and electrodes in high-voltage insulating medium. A dc potential is then applied across the electrodes to create an electric field across the material. The duration of application of the dc potential is sufficient to provide a large surface charge on the material. The material is then separated from the electrodes while it is still immersed in the insulating medium. The separated material is then removed from the medium to obtain a substantially permanently charged electret.

Abstract: A system and method for controlling the position and movement of an object in up to six desired degrees of freedom. The system comprises an armature which is provided with a distribution of electric charge. The armature may also include one or more magnetized regions. The system further comprises a base having components that may be actively controlled so as to cause a force to be exerted on the electric charge distribution of the armature. By appropriately controlling the components of the base, the position and movement of the armature with respect to the base can be selectively controlled.The base may also include passive electric and/or magnetic components which assist in stabilizing the armature in one or more degrees of freedom. In addition, the base may be provided with position sensors which provide position information to control circuitry such that the position and movement of the armature with respect to the base can be controlled automatically.

Abstract: An electretized material for a dust filter which is made of an insulating polymer material such as polypropylene incorporated with a fatty acid metal salt in an amount of not less than 100 ppm in terms of the metal.

Abstract: A backplate assembly for an electret transducer including a backplate, an electret layer covering one surface of the backplate, and a peripheral spacer on the same side of the backplate as the electret layer and around the entire periphery of the electret layer, the spacer being secured to the backplate by a thin layer of material of the electret layer located and compressed between the spacer and the backplate, the thin layer being substantially thinner than the electret layer. Also disclosed is using a peripheral ring to support a diaphragm spaced from a housing wall via support members extending from the ring.

Abstract: The present invention relates to a continuous method for manufacturing an electret filter medium from dielectric material having an open or porous structure, said method comprising the steps of continuously feeding a web of dielectric material with a substantially closed dielectric foil adjacent to at least one major face thereof into a corona discharge device, reducing the thickness of the web of dielectric material and charging the web of reduced thickness dielectric material by means of a corona discharge and to apparatus for carrying out said method.

Abstract: An electret transducer is comprised of a motor and signal processing apparatus, that may include an amplifier and/or impedance matching means, disposed within a sealed conductive housing. The motor is fabricated in place within a housing and the signal processing means is mounted on the underside of the cover for the housing so that each may be independently tested prior to combining into a unitary structure. The motor is comprised of easily fabricated and assembled components that include means for spacing a backplate from the walls of the conductive housing and a spacer intermediate the backplate and the center of a diaphragm. The backplate and the diaphragm are provided with registering apertures. The amplifier is mounted to the cover to conductively connect to the housing and to provide rigid outwardly extending terminals for ready connection to further electrical circuits, as in a hearing aid.

Abstract: To control the operation of a piezoelectric relay, control circuitry is disclosed for direct ohmic connection to a utility AC source to draw the minimal power required to actuate the relay's bimorph member pursuant to selectively switching power current through either one of two separate loads. The control circuitry, which is largely implimented in a single integrated circuit chip, utilizes isolating resistance and the capacitances of a voltage doubler circuit and the piezoceramic plate elements for transient suppression and circuit protection.

Abstract: The present invention concerns a dielectric film for converting electromagnetic or electrostatic energy into mechanical work, and a procedure for manufacturing the film. The film of the invention consists of a homogeneous film layer foamed to be of full-cell type and which has been oriented by stretching it in two directions and coated at least in part on one side or on both sides with an electrically conductive layer. The film is manufactured by extruding the plastic which has been made to be foamable, into tubular shape, performing intermediate cooling of the tube and reheating it, expanding the heated tube in two directions, metallizing the outer surfaces and cutting the tube open to become a film.

Abstract: Disclosed is a high-performance electret comprising 60 to 99% by weight of a non-polar polymer, 0.5 to 39.5% by weight of a polar polymer and 0.5 to 20% by weight of at least one component selected from the group consisting of (A) a non-polar polymer modified with an unsaturated carboxylic acid or a derivative thereof, (B) a non-polar polymer modified with an unsaturated epoxy monomer and (C) a non-polar polymer modified with a silane monomer having an olefinically unsaturated bond.In this electret, a high charge density can be maintained stably over a long period, and this electret can be easily formed into a film. An air filter prepared from this electret is very excellent in the dust collecting efficiency.

Abstract: A method for producing stable, layered electrets includes the steps of placing a thin sheet of glassy polymer or copolymer of high molecular weight, such as polyethylene terephthalate, between two, somewhat larger in planform, sheets of polyvinyl chloride and/or polyvinyl acetate formulation, to form a sandwich structure which is then compressed and heated to approximately 300.degree. F. At this temperature the exterior polyvinyl chloride or copolymer sheets are polarized and displaced under pressure over the interior sheet to charge the interfaces of the exterior and interior sheets. The heat, furthermore, bonds the peripheral edges of the larger exterior sheets to each other thus forming a hermetically closed container within which the charged interfaces will reside. Alternatively, two or more sheets of electret (polymer) material may be pressed and heated against each other to a point where plastic deformation occurs but below melting.

Abstract: An electret transducer and a method for making same. A multiple support between a diaphragm plate and a backplate is provided by a plurality of relatively small spacing disks made of an electrically insulating material and which as separate posts are fixedly attached on the upper surface of the backplate. Such spacing disks are conveniently and accurately punched from a foil of dielectric material which is held opposite and above the backplate, whereafter the spacing disks thus formed are attached on the backplate.

Abstract: A method of producing charged Teflon material having a stable internal positive charge is shown. Partially penetrating positive ions, which may be produced, for example, by a corona discharge or ion beam, are applied to Teflon at an elevated temperature, typically in excess of 100 degrees Celsius for high stability. It has been found that stable internal positive charges may be obtained thereby, having a stability at room temperature in excess of 2,000 years in some cases. This is comparable to the charge stability of negatively internally charged Teflon articles. Regions of both positive and negative internal charges may be included in the same article. Various charged Teflon devices may be made, including microphones, loudspeakers, electrostatic air filters, etc. Intermediate levels of charge stability, less than the maximum obtainable, may also be produced.

Abstract: Disclosed is an electroacoustic transducer structure which can be formed in a semiconductor substrate and incorporated as part of an integrated circuit, and which provides a built-in dc bias for operation. An appropriate density of fixed charge is provided in an insulating layer adjacent to one of the electrodes in the gap between electrodes. Methods of manufacture are also disclosed including means for introducing the charge by contacting the insulating layer with a liquid medium, plasma charging, or by ion beam implanting into the layer.

Abstract: An electret article comprising an even number of electret plastics films laminated together, with the surfaces of the same polarity facing each other, said laminate having the same polarity on both external sides. It keeps its high surface charge density. It will find use in such applications as acoustic materials, filters, and medical supplies.

Abstract: Apparatus for continuously making an electret tape having an electrically conductive strip with dielectric layers on opposite sides thereof in which the tape is moved vertically in the direction of its length. A pair of opposed electrodes connected to a high voltage source and continuously wetted with a dielectric fluid contact the respective dielectric layers to electrostatically charge each layer. A second pair of identical electrodes connected to the high voltage source and the dielectric fluid supply is spaced above the other electrode pair and repeats electrostatic charging of the dielectric layers to insure uniformity of charge thereon. Fluid on the layers is dried by air blown against them as the tape emerges from the second electrode pair.

Abstract: Apparatus for making an electret tape having an electrically conductive strip with a dielectric layer on one side thereof comprises tape supply and take-up reels arranged to move the tape from the former to the latter in an upwardly inclined plane and an electrostatic charging assembly between the reels having a dielectric fluid applicator for applying the fluid directly to the dielectric layer, a sponge-like electrode connected to a high dc voltage source, and an air blower for drying the fluid on the tape. The electrode is longitudinally spaced from the fluid application point in the direction of tape movement, engages the dielectric layer across its full width, and is wetted on the tape input side by the fluid on the layer. The blower is on the tape output side of the electrode with a baffle spaced closely to the dielectric layer between the blower and the electrode.

Abstract: This invention concerns a method for stabilizing polarized polymeric piezoelectric films wherein a polarized polymeric piezoelectric film is exposed to an electric field of reverse polarity to that employed in the polarization step for a period sufficient to remove unstable homo- and hetero-charges but insufficient to depolarize useful charges in the final film.

Abstract: An electret device having improved uniformity and lifetime of surface charge distribution, wherein a polarized dielectric body is secured at its one flat surface to a conductive electrode and attached to a plurality of discrete cover bodies at its other flat surface opposite to the conductive electrode. The plurality of cover bodies may be comprised of any conductive, semi-conductive or non-conductive material.

Abstract: A partition wall is held in contact with a back electrode on the opposite side from a diaphragm, and a fine acoustic path is formed in at least one of the contact surfaces of the partition wall and the back electrode. The acoustic path communicates with a sound hole made in the back electrode and a sound hole made in the partition wall. The velocity component of sound reaching the back of the diaphragm is controlled by the fine acoustic path.

Abstract: An electret device having its electric charges introduced to a remote electrode. A conductive electrode is secured to one surface of a polarized dielectric body. A cover body made of conductive material is attached to the opposite surface of the dielectric body, and a remote electrode is connected through a conductive wire to the cover body.

Abstract: An electret device having an improved surface charge in terms of high potential and uniformity of charge distribution. The electret device comprises negative and positive electret elements which are stacked upon each other in layers. Each electret element comprises a dielectric layer and a conductive layer. At least one outer end of the electret device is secured to a conductive electrode by a conductive layer of the electret element or a conductive outer plate stacked on the dielectric layer of an electret element.

Abstract: An electret device having improved uniformity of surface charge distribution, wherein a polarized dielectric body is secured at its one flat surface to a conductive electrode and attached to a cover body at its other flat surface opposite to the conductive electrode. The cover body may be comprised of any conductive, semi-conductive or non-conductive material.

Abstract: A method for producing stable, layered electrets includes the steps of placing a sheet of glassy polymer or copolymer of high molecular weight, such as polyethylene terephthalate, between two, somewhat larger in planform, sheets of polyvinyl chloride and/or polyvinyl acetate formulation, to form a sandwich structure which is then compressed and heated to approximately 300.degree. F. At this temperature the exterior polyvinyl chloride or copolymer sheets are polarized and displaced under pressure over the interior sheet to charge the interfaces of the exterior and interior sheets. The heat, furthermore, bonds the peripheral edges of the larger exterior sheets to each other thus forming a hermetically closed container within which the charged interfaces will reside.

Abstract: ABS thermoplastic material is rendered electrically conducting by the inclusion of carbon particles. When manufactured by a process of dry mixing of ingredients, melting, and molding, the material has desirably low sheet resistance even at relatively low levels of carbon content (as is desirable in the interest of plastic formability). The new material may be used in the manufacture of electret microphones.

Abstract: An electret transducer for producing a directional response, electret foil (92) and a backplate (94) with the actual air gap thickness therebetween varying in accordance with a predetermined relationship. The sensitivity of the electret transducer varies inversely as the actual air gap thickness. In one embodiment the actual air gap thickness is realized by a plurality of posts (90) having heights varying according to the aforesaid relationship. In another embodiment, the actual air gap thickness is realized by varying the thickness of the aforesaid backplate.

Abstract: A rough surfaced backplate has deposited thereon a metallic electrode having a plurality of large areas interconnected by thin strips. The large areas are symmetrically located on opposite sides of the center of the metallic electrode. Furthermore, the distances between the areas is nonlinear. Superimposed on the metallic electrode is an electret foil having a uniform electrostatic charge deposited on the polymer surface thereof.

Abstract: An acoustic transducer for producing highly directional characteristics comprises a metalized backplate (130) facing the flat surface (134) of an electrostatically charged electret foil (132). The thickness of the electret foil varies along the length thereof according to a predetermined relationship. The sensitivity of the electret transducer varies directly with the thickness of the electret foil.

Abstract: An electret transducer for producting a highly directional response characteristic comprises a backplate (18) and, superimposed thereon, an electrostatically charged electret foil (10). The electrostatic charge varies according to a predetermined relationship. The sensitivity of the electret transducer, at any point thereon, is directly proportional to the electrostatic charge on the electret foil at that point.

Abstract: An electret transducer comprises an electrostatically charged electret foil (10) superimposed directly over a selectively metalized rough surface (16) of a backplate (18). Selective metalization is realized by depositing a thin metal layer (20), the contour of which is defined by a predetermined relationship, over the rough surface (16). The sensitivity of the electret transducer at any point thereon is directly proportional to the width of the metal layer on the backplate. The response characteristic of the electret transducer comprises a main lobe and a plurality of sidelobes below a preselected threshold.

Abstract: A directional electret transducer comprises an electret foil and a metalized backplate the effective air gap thickness therebetween varying according to a predetermined relationship. The sensitivity of the electret transducer is directly proportional to the effective air gap thickness. The effective air gap thickness is realized in three ways: first, a plurality of equal diameter holes are drilled to varying depths in the aforesaid backplate; second, a plurality of holes of varying diameters are drilled through the aforesaid backplate; third, a plurality of equal diameter holes are drilled through the aforesaid backplate, the density of the holes varying. In each of the aforesaid three ways, the variation is according to the predetermined relationship.

Abstract: The invention relates to piezoelectric polymer films.The invention relates to a production process consisting of stretching a polymer material blank by rolling under an electrical field between two oppositely rotating rollers.The invention is more particularly applicable to the production of electromechanical transducers, whose active elements are constituted by piezoelectric polymer films provided with electrodes.

Abstract: An electret microphone has a metal shield around it in order to guard against electromagnetic interference. Acoustic waves reach the electret element through a passage in the shield. The electret response is undesirably affected by an electric field produced by body capacitance when the microphone is brought close to a user's mouth. To overcome this effect, the microphone has a conductive film, transparent to acoustic waves, positioned between the passage and the electret element, the film contacting a grounded part of the casing. The conductive film can form an integral part of a microphone moisture barrier.

Abstract: An electret transducer comprising a diaphragm (3) arranged between first (1 or 1') and second electrodes with at least one electrode (2) arranged at some distance from the diaphragm as a stationary electrode formed with holes (5). An air gap (4) is formed between the diaphragm (3) and said electrode (2). In the case of one air gap the air gap width d and the area A (7) enclosed by four holes which are situated nearest each other in said electrode (2) are selected so that the following equation is satisfied ##EQU1## where .eta. is the dynamic viscosity of the air in the air gap. In the case of an air gap on each side of the diaphragm, the air gap widths d.sub.1 and d.sub.2 and the said areas A.sub.1 and A.sub.

Abstract: This invention relates to electrets which comprise a film of plasma polymerized dielectric material having a volumetric space charge.

Abstract: A method for the manufacture of an electrically charged fibrous filter from a highly molecular non-polar fiber material wherein a .[.web.]. .Iadd.film .Iaddend.of the fiber material is continuously fed and stretched. At least one side of the stretched .[.web.]. .Iadd.film .Iaddend.is homopolarly charged by a plurality of corona charging elements. The charged .[.web.]. .Iadd.film .Iaddend.material is then fibrillated, collected and processed into a filter.

Abstract: .[.The invention relates to a flexible composite sheet designed to constitute an undersheet behaving as an electromechanical transducer in order to detect the apnea of subjects lying on it. This sheet comprises, in addition to a foil sensitive to pressure in the sense of electromechanical transduction (an electret or polarized piezoelectric foil), two film electrodes and two protective foils. Spacing shims are glued to the two foils against which they are juxtaposed. When the sensitive foil is an electret, the shims are directly interposed between the sensitive foil and one of the two electrodes. When the sensitive foil is a polarized piezo-electric foil, the shims are directly interposed between one of the electrodes and the corresponding external protective foil..]. .Iadd.An apnea monitor/alarm consists of an electronic monitor circuit to actuate an alarm responsive to the output of a sheet-like electromechanical transducer.