Abstract: One PWM control circuit is located in the primary side of a power converter and is isolated from the secondary side, and another PWM control circuit is located in the secondary side of the converter and is isolated from the primary side. The first PWM control circuit is powered by a direct tap to the input line of the converter and, during start-up, supplies a low power square wave coupled directly to switching transistors of an inverter of the power converter. After start-up, the second PWM control circuit is powered by a direct tap to the secondary side and supplies a regulating square wave output to the switching transistors through an isolation component such as a coil. After start-up, the primary PWM control circuit is disabled so that, under normal operating conditions, the power supply is regulated only by the second PWM control circuit.

Abstract: An aircraft seat frame includes a plurality of upright seat supports each formed in one piece of heat-conductive material. Heat-generating electronics are thermally coupled to one of the supports. Such support acts as a heat sink to conduct and dissipate heat away from the electronics.

Abstract: The impeller and drum of a motorless in-line mass flowmeter are constructed with small optical targets having high reflectivity. Light is pulsed toward the path of rotation of the targets through optical fibers. The pulse width is small in comparison to the delay between pulses. Reflections of the pulses from the optical targets are conveyed by a single output fiber to a remote location where the optical pulses are converted to electrical pulses. The electrical pulses can be analyzed to determine the speed of the impeller and the deflection angle of the impeller relative to the drum, for accurate determination of the mass flow rate of liquid passing through the flowmeter.

Abstract: A generally rectangular housing base or body portion has an upward-opening central cavity and mounting ears extending from each corner. A wiring board on which electronic circuit components are mounted is supported in the cavity of the base. Each end portion of the wiring board extends from the cavity between two of the mounting ears. The top of the cavity is closed by a lid to enclose the circuit components. The opposite ends of the wiring board projecting from the housing cavity are adapted for connection of different pin or stud terminal connectors so that the housing-board unit is capable of being easily joined to or arranged with other electrical parts or units.

Abstract: A free-space optical communications system for transmitting data between an aircraft computer system (14) and a ground-based computer system (12). The system includes a pair of corresponding optical transmitters (36) and optical receivers (38) that transmit and receive optical signals transmitted between the two computer systems. Included within each optical transmitter is one or more light-emitting diodes (42) that produce optical signals corresponding to the data to be transmitted. A beam-forming prism (44) is bonded directly to the light-emitting diodes to direct the optical signal uniformly over a target area. The optical receiver includes one or more infrared windows (50) to reduce the amount of ambient light received by the optical receiver. A compound parabolic concentrator (64) collects light transmitted from the optical transmitter and directs the light onto an avalanche photodiode (66), which includes thermal bias compensation.

Abstract: A variable reluctance saturable core proximity sensor assembly comprising a target and a sensor. The target consists of a magnet having a high field strength, a base plate having a high relative permeability, and a nonmagnetic metal housing surrounding the magnet and base plate. The sensor consists of a core made from a material having a high relative permeability, a coil surrounding the core and a housing made from a nonmagnetic material surrounding the core and coil. At its distal end of the core is a flux director that intercepts the magnetic field produced by the target. The flux director comprises a plurality of radially extending arms having the same permeability as the core. The flux director has a cross-sectional area selected so that the flux director and core saturate at substantially the same time. The sensor assembly may be used in either a slide-by or head-on mode.

Abstract: Disclosed is an inductive divider sensor that comprises a variable inductor (12) connected in series with a fixed inductor (16) between a source of AC voltage and ground. A target element (18) is moved by an object whose position is to be sensed along an axis that extends through the variable inductor thereby changing its impedance. The impedance of the variable inductor is designed to vary such that the voltage taken at a node where the variable inductor and fixed inductor are connected varies according to a predetermined linear output signal.

Abstract: A communications system for transmitting optical signals between an optical transceiver (20) disposed on an aircraft and a ground-based computer system. The communications system includes a fiber optic cable (30) having one end coupled to the ground-based computer system and another end coupled to a magnetic attachment head (40). The magnetic attachment head secures the fiber optic cable to the aircraft and aligns the fiber optic cable with the optical transceiver.

Abstract: A variable reluctance saturable core proximity sensor assembly comprising a target and a sensor. The target consists of a magnet having a high field strength, a base plate having a high relative permeability, and a non-magnetic metal housing surrounding the magnet and base plate. The sensor consists of a core made from a material having a high relative permeability, a coil surrounding the core and a housing made from a non-magnetic material surrounding the core and coil. The sensor assembly may be used in either a slide-by or head-on mode. Depending upon the configuration of the sensor, the assembly may be used as either a proximity sensor or as a distance sensor.

Abstract: A power supply system for controlling the drive voltages applied to a thin film electroluminescent (TFEL) display panel is disclosed. The system includes a power supply that generates the drive voltages to the TFEL display panel and causes it to emit light. A replaceable or resettable display voltage memory located adjacent the display panel provides the power supply with voltage information specific to the display panel. A feedback circuit measures the light emitted from the display panel. A balancing circuit controls multiple display voltages so that they have the proper relationship with respect to each other. The information from the display voltage memory and the feedback circuit is used by the power supply to control the output of the display voltages.

Abstract: A frame (10) for holding an electrical component (34) that is to be mounted on a printed circuit board is provided. A board (12) is folded to form a pocket (20) having sidewalls (22 and 24) and a floor (26). The board is further folded to form flaps (28 and 30) connected to the sidewalls and lying adjacent the sidewalls outside the pocket. A plurality of terminal wires (14.sub.1 -14.sub.n and 15.sub.1 -15.sub.n) are inserted into a plurality of spaced apart hole pairs (16.sub.1 -16.sub.n and 17.sub.1 -17.sub.n) located in the flaps. Ends (40.sub.1 -40.sub.n and 44.sub.1 -44.sub.n) of the terminal wires are connected to lead wires (36.sub.1 -36.sub.n and 37.sub.1 -37.sub.n) of the electrical component contained in the pocket. Other ends (42.sub.1 -42.sub.n) of the terminal wires may be connected to a printed circuit board. The other ends (42.sub.1 -42.sub.n and 46.sub.1 -46.sub.n) are spaced apart a predetermined distance.

Abstract: A dual transformer device (34) for use in a power converter (30) is provided. The dual transformer device is preferably implemented as an integrated magnetics device suitable for use in high density power converters. Two transformers, T1 and T2, have series connected primary windings (300 and 302), and secondary windings (304 and 306) connected at a common node (312). T1 and T2 have magnetizing inductances, L1 and L2, that independently store energy responsive to an AC voltage, V.sub.p. Diodes, D1 and D2, operate to rectify substantially out-of-phase secondary voltages, V.sub.S1 and V.sub.S2 and produce a rectified voltage V.sub.R. D1 and D2 cause L1 and L2 to store discharge energy such that the magnitude of an output current, I5, is always equal to the sum of magnetizing currents, I.sub.L1 and I.sub.L2. An output filter (38) reduces current ripple in I5 and voltage ripple in V.sub.R. Another inductance, L3, supplies energy to an AC voltage supply (32) to reduce switching losses.

Abstract: A method and apparatus for sensing the proximity of a target object includes a sensor inductor (L.sub.S, 38) connected in series with an identical reference inductor (L.sub.R, 36) between an input and ground to form an inductive divider network. The sensor inductor is positioned so that its inductance can be varied in response to the proximity of a target object (14, 40) while the inductance of the reference inductor remains constant. Voltage pulses are periodically applied to the divider network from a source (32, 34) and divide across the reference and sensor in accordance with the ratio of the inductances, as varied or not by the presence of the target object. A detector (30) monitors the output of the divider network and provides a target status signal indicative of the proximity of the target object. For low-power operation, the detector circuit and conductive divider network are periodically and momentarily energized in synchronism.

Abstract: Disclosed is an improved fiber optic sensor of the type in which a fiber optic waveguide component of the sensor is configured to be responsive to an external parameter such that curvature of the fiber optic waveguide is altered in response to forces induced by changes in the external parameter being sensed. The alteration of the curvature of the fiber optic waveguide causes variations in the intensity of light passing therethrough, these variations being indicative of the state of the external parameter. The improvement comprises coating material covering the exterior portion of the fiber optic waveguide, the coating material having an expansion coefficient and thickness such that distortion of the fiber optic waveguide caused by thermally induced stresses between the coating material and the glass fiber is substantially eliminated.

Abstract: Disclosed is a fiber optic sensing system wherein a pulsed light source signal (12) propagates along a single optical waveguide (14) and is split into component signals (20) and (22) at a sensor unit (16). The intensity of one component signal (20) is varied by a transducer (28) through which the signal passes. The second, reference, component signal (22) passes through a delay optical fiber (30) and has its propagation delayed with respect to the other component signal (20). The delayed and undelayed component signals are then coupled and propagate along a single waveguide (34) to a receiver (36). The system is constructed so that intensity-varying factors inherent in the system, other than the sensor-induced variations, are identically shared by the two component signals. Accordingly, signal processing circuitry (38) calculates a simple ratio of the delayed and undelayed signals which yields the sensor-intensity variation independent of any other intensity-varying factors.

Abstract: A physically integrated assembly of tow magnetically independent transformers and two semiconductor rectifiers, arranged to minimized leakage and parasitic lead inductances, and the resultant voltage dropout during current commutation from one transformer-rectifier to the other. In a suitable circuit this assembly produces a nearly pure DC output voltage, which requires a minimum amount of filtering. It is also possible, when a choke input filter is required in the output, to integrate the filter choke into the same physical assembly, using part of the existing tranformer core material. The choke is magnetically independent of the transformers.

Abstract: A fiber optic sensor for determining the position of a shaft 10 that is supported by a bearing 12 includes a sensor circuit 14 and at least one fiber 16 that extends from the sensor circuit to a point proximate but slightly separated from the shaft surface, with a portion of the optical fiber extending through and being carried by the bearing. Target areas 18, 20 and 22 are located on shaft 10 so as to correspond to the positions to be determined. Each target area consists of an angled recess that is constructed and arranged, relative to the numerical aperture and orientation of the optical fiber, so as to substantially nonreflective insofar as the optical fiber is concerned, thus providing a sharp contrast to the highly reflective background of the shaft surface.