Abstract: A method and system is disclosed for allowing users to consolidate a large number electronic keys (for operating mechanical locks) in electronic key assemblies. These electronic keys are easily duplicated, added to, removed, backed up, or upgraded. The electronic key assemblies are also more resistant to tampering. The lock assembly and electronic key designs taught by the invention are customizable to meet various security needs. The lock assembly includes a transmitter and a receiver operatively coupled to an electronic circuit in communication with a store for keys. The electronic circuit is also coupled to the mechanical levers for operating the lock assembly. The electronic key assembly also has its transmitter, receiver, a control circuit and a user interface for selecting a particular electronic key password.

Abstract: A tricolor LED display system (10) is provided having a plurality of multi-color LEDs (22) that operate as concurrent display and data communication elements. These dual-use tricolor LEDs are coupled to a special-purpose computer system (12) and audio signal transmitter (16) for simultaneously controlling the visible display signal from the LEDs, and for modulating audio information onto the visible light signal emitted by the LEDs. A receiver circuit (24) receives the modulated visible light signal from the LEDs and demodulates the received signal to recover the audio information, which is then presented to a user of the system through an audio interface.

Abstract: A dot matrix display system made up of light emitting diodes (LED's), n which one or more LEDs are modulated and encoded with audio information or messages is disclosed. The system has a LED dot matrix display panel with an interface circuit to a computer, an audio signal transmitter, and a receiver. An executive program runs on the computer for the visual display control of characters, decorative pattern or messages on the display panel. The receiver combined with a speaker is located at a distance from the display panel. The receiver is designed to demodulate the optically transmitted audio information and broadcast the messages with the speaker. The modulation of the LEDs includes a voltage-controlled oscillator (VCO) for varying the frequency of on/off periods of said light emitting diodes. The frequency is high enough such that the perceivable light appears to be constantly illuminated to the human eye.

Abstract: A handy information display system is disclosed. The system has three main components: a light emitting diodes (LED) array display board, an information server and a portable unit. The LED array display board includes a plurality of light emitting diodes and photodetectors. It can be used to display alphabets, numbers and simple graphics. While it visually gives an effectively stationary message display, the LED can also be modulated to transmit high frequency signals. The modulating frequency should be high enough to be imperceptible by humans. Both message display and signal transmission are controlled by an information server. The system further comprises at least one portable unit. The portable unit is equipped with an optical transceiver and a visual display unit. The optical transceiver can detect the signals transmitted from the LED array display board. The visual display unit then shows the information corresponding to the received signals.

Abstract: In an integrated heterojunction bipolar transistor (HBT) with minimized base-collector capacitance, a sub-collector region is formed as a mesa on a substrate, a collector contact is to the sub-collector mesa region, a lightly-doped collector region and a base region extend from the mesa onto the substrate, and a base contact and its via hole for interconnection are off the mesa, with minimal overlap with the sub-collector region. The latter may be termed a buried selective sub-collector (BSSC) region. Such transistors can be used as integrated switching devices and microwave devices, e.g., in wireless communications, satellite direct broadcast systems, automobile collision avoidance systems, global positioning systems, and other high-frequency applications.

Abstract: An HBT device having heterostructure ballasting emitter is disclosed. The heterostructure ballasting emitter includes an n-type emitter setback layer on a base layer and a wide-gap ballasting emitter layer on the setback layer. The heterostructure ballasting emitter is made so that the band gap of the emitter setback layer is equal to or larger than that of the base layer and the band gap of the ballasting emitter layer is larger than that of the emitter setback layer. The heterostructure of the emitter setback layer and the ballasting emitter layer serves as the ballast. By changing the value of the valance offset between the emitter setback layer and the ballasting emitter layer, the temperature dependence of the current gain becomes adjustable. As a consequence, the present invention overcomes hurdles posed by the current gain collapse and a negative differential resistance and improves the use of the HBTs in microwave power applications.

Abstract: In a method of patterning superconducting thin films such as YBaCuO, based on the inhibition of superconductivity by intermixing an impurity, such as silicon, with superconductor material, a thin film of silicon is formed on a magnesium oxide substrate and then patterned, by laser direct-writing for example, to correspond to a desired pattern of superconducting lines. Multilayered YBaCuO thin films are then deposited over the patterned silicon film and annealed using rapid thermal annealing at a temperature of 980.degree. C. maintained for a period in the range from 30 to 90 seconds. The rapid annealing results in intermixing of silicon and YBaCuO in regions of the film between the lines of the pattern which, in turn, causes these regions to become insulating, and at the same time causes the YBaCuO film over the line pattern to become superconducting.