Materials Systems, Inc.

Craig D Near

Leslie J Bowen

Brian G Pazol

Richard L Gentilman

A multilayer capacitor includes a unitary, net-shape molded dielectric ceramic body having first and second cavities molded into at least one side to divide the ceramic body into a plurality of ceramic layers disposed generally parallel to the top. The first cavities alternate with the second cavities in the ceramic body. Each of the ceramic layers except an uppermost and a lowermost of the ceramic layers is joined at one edge to one ceramic layer adjacent thereto by a first ceramic bridge and at the same or a different edge to another ceramic layer adjacent thereto by a second ceramic bridge. The first and second cavities are filled with one or more materials to form first and second electrically conductive electrode layers, respectively, each electrode layer being bonded to the ceramic layers adjacent thereto. The first electrode layers are electrically interconnected to provide a first set of electrode layers, and the second electrode layers are electrically interconnected to provide a second set of electrode layers alternating with and electrically isolated from the first set electrode layers in the body.

Multilayer capacitor and method

An actuator includes a ceramic body having a base and an array of tube-shaped or blade-pair-shaped piezoelectric or electrostrictive ceramic elements defining an enclosure and integral with the base. A first electrode contacts the inner surfaces of walls of the elements, while a second electrode contacts the wall outer surfaces. The actuator is driven for d.sub.31 mode or d.sub.15 mode vibration of the walls. The wall vibration is transmitted to a desired medium via a vibration transmission means, e.g., a compliant polymer filler material of Shore A30 to Shore D75 filling the enclosure and bonded to the walls. Alternatively, a stiff cover plate may be used to transmit the tube wall vibration to a desired medium. An acoustic sensor device is also described.

Low voltage piezoelectric actuator

A serpentine cross-section piezoelectric linear actuator includes a unitary, densified, rigid, monolithic piezoelectric or electrostrictive ceramic body, the body including a top, four sides generally normal to and interconnected with the top, a base generally normal to and interconnected with the sides, and two or more ceramic layers including a top ceramic layer providing the top, a bottom ceramic layer providing the bottom, and, optionally, one or more intermediate ceramic layers, the layers being disposed parallel to and superimposed over one another. Each ceramic layer except the top ceramic layer is joined at a first side to one of the ceramic layers adjacent thereto by a first ceramic bridge and each ceramic layer except the bottom ceramic layer is joined at a second side opposite the first side to another of the ceramic layers adjacent thereto by a second ceramic bridge. First and second cavities extend into the ceramic body from the first and second sides, respectively, the first cavities alternating with the second cavities in the ceramic body, so that the ceramic body has a serpentine cross-section. The body further includes a first electrode and a second electrode, each of an electrically conductive material. The first and second electrodes are disposed along and bonded to the first and second sides, respectively, of the body for activation of the actuator. The actuator may be poled and electroded in, e.g., a d.sub.33, d.sub.15, or d.sub.31, configuration for linear expansion of the actuator.

Serpentine cross-section piezoelectric linear actuator

A transducer including a ceramic body having a base and an array of tube-shaped piezoelectric or electrostrictive ceramic elements integral with the base. A first electrode contacts the tube wall inner surface, while a second electrode contacts the tube wall outer surface and is electrically isolated from the first electrode and from the lower surface of the transducer. The first electrode extends onto the transducer lower surface for electrical connection to a power source for driving the transducer across the tube walls for d.sub.31 mode vibration of the tube walls. A stiff cover plate may be used to transmit the tube wall vibration to a desired medium. The ceramic base may be removed if an electrically insulating layer is provided between the elements at the lower surface of the transducer. The insulating layer and tube wall upper edges then electrically isolate the second electrode from the first electrode and the transducer lower surface. In this alternative, the first and second electrodes are provided by a stiff conductive polymer matrix filling the tube-shaped elements and spaces between the elements. The matrix upper surface transmits the tube wall vibration to a desired medium without a cover plate. The first electrode extends onto the composite body lower surface for electrical connection to a source of electric power for driving the transducer across the tube walls for d.sub.31 mode vibration of the tube walls. A net-shape molding method for producing the transducer is also described.

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Acton, MA, United States of America

Craig D Near