American Research Corporation of Virginia

American Research Corporation

Lawrence H Decker

Howard P Groger

Russell J Churchill

K Peter Lo

Usha Varshney

Howard J Moses

Nicholas V Nechitailo

The vibration and electrical characterization of a piezoelectric tactor actuator is described. The actuator is a rectangular laminated flat plate with two opposite sides simply supported and two others free. Under an axial compression from the supports, the plate deforms into a stressed shallow shell. Electrical high frequency harmonic signals within relatively low-frequency bursts are applied to the piezoelectric layers. Depending on the axial compression and pre-deflection, frequency and magnitude of electrical input, the tunable actuator exhibits frequency/mode-controlled high-force over large area vibrations with intense displacement jumps. A single-degree-of-freedom model and simplified 1-D models are provided. The tactor provides efficient conversion of electrical energy into mechanical.

Piezoceramic vibrotactile transducer based on pre-compressed arch

A refreshable braille cell display uses a single moving part per tactile element. Tactile elements, formed from stainless steel tubing, are assembled in densely arranged modules. Lower ends of the tactile elements extend beneath the modules and are in contact with a pressurized medium. Shape memory alloy actuators are positioned in the tactile elements, isolated from any motion or flow in the pressurized medium. When a pressurized medium is delivered through a port in a tactile element, the actuator extends upward, thereby forcing the upper portion of the tactile element through a hole in the user contact surface. In that state the tactile element indicates information. When the tactile element is activated, current flows from an electrical contact at the lower end of the tactile element, through the actuator, and into the outer tube of the tactile element. The actuator heats, due to electrical resistance, contracts and exerts a downward force on the pressure medium. The upper portion of the tactile element is drawn below the user contact surface, indicating the absence of information. Distributed pulse width modulation allows instantaneous power requirements to be minimized, and only low safe voltages are needed to operate the array. By applying a bias force to all actuators via a common reservoir of either pneumatic or hydraulic pressure, the design is simplified, and reliability is increased. When integrated with a computer, the refreshable tactile array of elements gives users access to full computer generated screens of text and graphical information in real time.

Refreshable braille-cell display implemented with shape memory alloys

A laser ablation deposition system includes a movable platform for supporting ferroelectric target material and a support structure for supporting a thermally sensitive semiconductor substrate within a chamber mounted on a moveable cabinet, and a laser for ablating the material mounted on a support frame along with various control components. The cabinet with the chamber may be moved away from the laser and support frame to allow the chamber to be raised to provide access to the components within the chamber. The system may be used to fabricate a multilayer thin film device using multicomponent oxides.

Integrated laser ablation deposition system

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Christiansburg, VA, United States of America

Lawrence H Decker