Abstract: Electrical equipment (14) is safeguarded from damage due to parallel arc faults by a circuit that provides several levels of protection. A semiconductor switch (18) and a current sensor (24) are placed in series with the electrical equipment (14). When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch (18) is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch (18) in conductive and non-conductive states so that the average current applied to the equipment (14) is within an acceptable level. The pulses are measured to determine whether a parallel arc fault has occurred. When the measured pulses (74) are within a predetermined range, a parallel arc fault is declared and the semiconductor switch (18) is rendered non-conductive.

Abstract: Arcing in dc electrical systems subject to cyclic disturbances is detected by a current sensor, and a bandpass filter sensitive to arcing noise, which filters the sensor current. The absolute value of the bandpass filtered signal is integrated over repetitive intervals in a resettable analog integrator. A low cost microprocessor samples and resets the analog integrator at a frequency below the pass band and generates a time attenuated accumulation of the samples that produces an arcing signal if it reaches a predetermined limit. To improve nuisance immunity, the sensed dc current is compared in a high speed comparator to the average sensed dc current, and only samples taken by the microprocessor during a predetermined time period after the sensed dc current exceeds the average sensed dc current in a predetermined manner are accumulated. The average sensed dc current is also used by the microprocessor to provide overload protection.

Abstract: A protection sensor for a lawn vehicle includes a substantially unidirectional antenna operatively coupled to a Doppler detection circuit. The Doppler detection circuit generates a radio frequency signal which is radiated by the antenna. When the radiated signal strikes an object, such as a person, animal or another moving lawn vehicle, within a predefined detection region of the sensor, the signal is reflected and received by the antenna. The Doppler detection circuit generates an output signal responsive to a difference in frequency between the radiated signal and the reflected signal, thereby indicating the presence of the moving object within the protection region of the sensor. The unidirectional antenna virtually eliminates false detections generated by the lawn vehicle, to which the sensor is mounted, or by the operator of the vehicle.

Abstract: A backup proximity sensor for a vehicle includes a first passive infrared sensor (PIR) and a second PIR vertically mounted with respect to one another on a pivotal support member. The first PIR and second PIR are angularly directed such that the respective fields of view converge, establishing a detection zone in a region behind a vehicle. A drive motor and scanning gear box are coupled to the pivotal support member and pivotally drive the first and second PIR in an oscillatory fashion about a predetermined arc. This establishes relative motion between the PIRs and a stationary warm body in the field of view of the two sensors, allowing the stationary body to be detected. A detection circuit receives output signals from the first PIR and second PIR and generates an output signal indicative of a warm body being detected by both the first and second PIRs. This eliminates false alarms generated by warm bodies outside the region of the desired detection zone.

Abstract: A back-up proximity sensor for a vehicle is formed with an array of sensor pairs. Each sensor pair includes a lower passive infrared sensor (PIR) having a first field of view and an upper PIR having a second field of view. Each lower PIR and upper PIR is vertically mounted with respect to one another. The lower PIR and upper PIR of each sensor pair are angularly directed such that the respective fields of view intersect, thereby establishing a detection zone in a region behind a vehicle. The sensor pairs are arranged in a substantially adjacent, semicircular configuration to provide a continuous area of coverage behind a vehicle. A detection circuit receives output signals from each sensor pair and generates an output signal indicative of a warm body being detected by both the upper and lower sensors in a selected sensor pair, eliminating false alarms generated by warm bodies outside the region of the desired detection zone.

Abstract: An electromagnetic, reflective type, active proximity sensor includes a transmitter, the transmitter including a voltage controlled oscillator circuit, a transmitter circular waveguide and a transmitter polarization circuit. The voltage controlled oscillator circuit generates an output signal which is modulated such that the frequency of the output signal varies over time between a range of frequencies. The frequency varying, output signal is provided to the transmitter circular waveguide and propagated to the transmitter polarization circuit where it is circularly polarized in a first circular direction. The circularly polarized, frequency varying, output signal is radiated by the transmitter to the target, where it strikes the target and reflects back toward the sensor to form return signals. The return signals, upon being reflected, rotate in a second circular direction opposite to the first circular direction.

Abstract: Arcing faults in an ac current are detected by apparatus which is responsive to a predetermined randomness in step increases in the current to eliminate false tripping caused by regularly occurring discontinuities produced by loads such as dimmers. A signal conditioner generates a bandwidth limited di/dt signal having pulses produced by the step increases in current. In one embodiment, a first tracking circuit tracks the envelope of the di/dt signal with a first time constant. A second tracking circuit also tracks the di/dt envelope, but with a second, shorter time constant. An arcing fault is indicated if the second tracking signal falls to a predetermined fraction of the fist tracking signal. This circuit may be used alone to detect arcing faults or to increase the sensitivity to arcing faults over dimmers of a circuit which responds to a time attenuated integrated valve of the pulses in the di/dt signal.

Abstract: A low power, low cost, millimeter wave (MMW) proximity sensor that provides over a 6:1 increase in minimum detection range (55 mm minimum) compared to standard 18 mm inductive proximity sensors preferably includes a low cost MMW Gunn oscillator, MMW detector and analog processing/driver circuitry. The sensor is preferably designed for 3-wire operation and will fit in a standard 18 mm tube.

Abstract: A control system for a washing machine having a transducer mounted on the exterior of the washing receptacle wall and operable to generate acoustic vibrations in the receptacle wall during fluid filling of the receptacle. A receiver detects sound waves within the receptacle generated by the wall vibrations and generates in fill signal indicative of the sound waves. Circuitry is provided for analyzing the fill signal and determining from the acoustic signature of the fill signal the occurrence of total immersion of articles in the fluid; and, the circuitry sends a signal which is operable to then shut off the fluid fill valve.

Abstract: A capacitive switch assembly formed on a glass substrate with one capacitive plate formed of a thin metal film deposited thereon covered by a dielectric spacer deposited thereover for spacing therefrom a second plate formed of conductive polymer paste screened on the dielectric spacer. Discontinuities are provided in the second plate which is brought in-circuit by a conductive elastomer shorting bar movable upon user actuation of the switch.

Abstract: Pivotal movement of a switch actuator drives a finger projecting from the actuator against a convexly bowed leaf spring, depressing an intermediate portion of the leaf spring to an unstable concave condition. The leaf spring resists the actuator movement, initially with an increasing force but changing to a decreasing force at a predictable point in actuator movement to provide tactile feedback at an operator affixed to the actuator. The leaf spring is a flat beam. The spring force and point of changeover can be readily and predictably varied during manufacture by selecting springs having different widths, thicknesses or other variable parameters. A modular block holds the spring in the bowed condition and is positioned relative to the actuator finger by a support plate. The actuator finger drives the spring against a conductive rubber block, compressing the block against spaced conductors on a printed circuit to complete the circuit.

Abstract: Pivotal movement of a switch actuator drives a finger projecting from the actuator against a convexly bowed leaf spring, depressing an intermediate portion of the leaf spring to an unstable concave condition. The leaf spring resists the actuator movement, initially with an increasing force but changing to a decreasing force at a predictable point in actuator movement to provide tactile feedback at an operator affixed to the actuator. The leaf spring is a flat beam. The spring foce and point of changeover can be readily and predictably varied during manufacture by selecting springs having different widths, thicknesses or other variable parameters. A modular block holds the spring in the bowed condition and is positioned relative to the actuator finger by a support plate. The actuator finger drives the spring against a conductive rubber block, compressing the block against spaced conductors on a printed circuit to complete the circuit.

Abstract: A moisture sensor (100) is provided that utilizes a sulfonated fluorocarbon film (10) having a thickness of less than about one micron and capable of providing accurate measurements of humidity and extremely fast response to change in humidity. A preferred embodiment of an electrical system (150) is disclosed for use with sensor (100) and a sulfonated tetrafluoroethylene perfluoroether copolymer form of the film is especially preferred.

Abstract: The depth of a cavity or chamber (10') is measured by using the chamber as the resonator of an electronic oscillator (24) whose oscillations are coupled to fluid in the cavity by transducers (12, 13). Both the variable-depth main chamber (10') and a reference chamber (117) of fixed depth are measured. Variations in the data obtained from the chambers are caused by factors affecting the velocity of propagation of sound in the fluid. An accurate measurement of the depth of the main chamber is obtained by compensating direct data (at 42) obtained from the main chamber (10'), using, data (at 43) obtained from the fixed-depth reference chamber (117). In one embodiment an inertance orifice (121) is utilized between the two chambers. The fluid inertance of the orifice, together with the compliance of the fluid in the main chamber (10'), form a resonant system whose anti-resonant frequency is a measure of the dimensions of the main chamber. (Inertance is the acoustical equivalent of inductance.

Abstract: A nozzle structure in a crystallographically oriented, monocrystalline silicon includes a pyramidal opening anisotropically etched from the entrance side of the nozzle and truncated in a membrane having a smaller cross-section than the initial cross-section of the entrance opening. The membrane has extending therethrough a pyramidal opening etched anisotropically from the exit side. The vertical axes of both openings are substantially concentric.

Abstract: An integrated circuit 14 having an active circuit 19 is formed on a circuit wafer 10. A moat 18 in the field oxide 20 surrounds the active circuit 19. Metallic conductor 30 passes from a location on the active circuit 19 over the moat 18 to a contact area 22. The wafer 10 is covered with a photoshaped silicon nitride layer 18, and a support wafer 40 is secured with adhesive 46 to the circuit side of the circuit wafer 10. The circuit wafer 10 is photoshaped to expose the metallic conductor 30 at the contact area 22, and the contact area 22 is prepared with multiple metal layers 62, 66, 70 for connection to external wiring.

Abstract: A method for manufacturing an integrated circuit thermal print head is illustrated including transistor 20 and a resistor doped region 22 formed on a first surface of a silicon circuit wafer 10. A contamination barrier in the form of a moat 26 filled with silicon nitride 30 is formed around the transistor 20. A support wafer 50 is secured to the first surface of the circuit wafer 10 by an adhesive layer 58. The circuit wafer 10 is thinned, and the exposed surface of the circuit wafer 10 is photoshaped to define wafer segments 68 positioned over the resistor doped region 22.

Abstract: A method for manufacturing an integrated circuit device illustrates the preparation of the first surface of a circuit wafer including the placement of fine alignment indicia 34a outside the active chip area. A support wafer 50 is secured to the first surface of the circuit wafer 10 by an adhesive layer 58. The circuit wafer 10 is thinned. Openings 66 are photoshaped in the circuit wafer 10 using wafer flats 51 for alignment. The openings expose alignment indicia 34a which are relief images in the adhesive of the alignment pattern 34. The exposed surface of the circuit wafer 10 is photoshaped, using the indicia 34a for alignment, to define wafer segments 68 positioned over resistor doped regions 22.