Abstract: An arrangement for igniting and operating a high-pressure discharge lamp provided with a Buck converter for supplying the lamp through periodic switching of a switching device which is held alternately in a conducting state for a period t.sub.on and in a non-conducting state for a period t.sub.off. The arrangement further includes circuitry which produces fixed minimum and maximum time limits for the time duration t.sub.off.

Abstract: A ballast including an inverter and a circuit having a resonant frequency coupled to the output of the inverter. In one embodiment of the invention, the only discrete type of element substantially affecting the resonant frequency is substantially inductive in electrical character. In this embodiment of the invention, there is also no discrete ballasting element in series with the lamp load. The reduction in discrete elements reduces both power consumption and costs associated with the ballast.

Abstract: An integrated circuit control device for driving a half bridge type of inverter. The IC control inverter powers a load including a lamp. The device includes at least one pin, which during the preheat cycle of the lamp is at a high logic level resulting in the coupling of an additional capacitor to an unloaded resonant tank circuit. The overall resonant frequency of the unloaded circuit is reduced making it less likely that a high voltage will be applied to the lamp during preheat. Once the lamp filaments have been preheated the pin is at a low logic level. The low logic level at the pin causes the additional capacitor to be decoupled from the tank circuit. The pin when at the low logic level also receives a signal representing the voltage condition across the lamp.

Abstract: A circuit arrangement for igniting and operating a discharge lamp is provided with input terminals for connecting a supply source and a commutator having output terminals for connecting a lamp to be operated, the commutator including at least two switches which are alternately in a conducting and a non-conducting state. The commutator is suitable for pulse width modulation (PWM) operation of the switches. The switches and an output terminal are connected to one another by coupled inductors for this purpose.

Abstract: A control circuit controls the power supply to an electric motor and, comprises a power transistor NM of the NMOS type and a power transistor PM of the PMOS type arranged between two supply terminals VCC and GND, their intermediate node forming an output coupled to a coil Ei of the motor. The well B of the transistor PM is coupled to supply terminal VCC via an isolation diode ID, which has its anode connected to supply terminal VCC and has its cathode connected to the well B. The isolation diode ID ensures that the coil Ei is not short-circuited by the parasitic drain-well diode D of the transistor PM in case of a sudden power failure.

Abstract: A triac dimmable compact fluorescent lamp including a power feedback circuit. The power feedback circuit helps to maintain the level of current drawn from the triac to at least the level of the triac holding current especially during low dim levels. In one preferred embodiment, the feedback circuit is fed into a junction joining together a pair of fast recovery diodes for converting the high frequency square wave signal into a unidirectional signal supplied to an inverter. Overboost voltages across a buffer capacitor are minimized during low dim levels.

Abstract: An arrangement for igniting and operating a high intensity discharge lamp including a Buck converter. The Buck converter includes a switch, a rectifier and an inductor. The converter is connected to input terminals for connection to a supply source and output terminals for supplying the lamp with a current through periodic swithing of the switch alternately into a conducting and a non-conducting state. The Buck converter operates in a self-oscillatory mode during stable lamp opertion. The arrangement further includes circuitry for causing the Buck converter to operate in a forced oscillatory mode in dependence on the lamp condition.

Abstract: The invention relates to a circuit arrangement for operating a discharge lamp with a high frequency current comprising a power feedback circuit and an electrode preheater. The circuit arrangement comprises an antiboost switch for disabling the power feedback circuit before the lamp has ignited and enabling the power feedback circuit after the lamp has ignited. In accordance with the invention the antiboost switch is also used to enable the electrode preheater before the lamp has ignited and to disable the electrode preheater after the lamp has ignited.

Abstract: A circuit arrangement suitable for igniting a high-pressure discharge lamp and provided with input terminals for connection to a voltage source. A pulse generating circuit includes a switch, a primary winding of a pulse transformer, and a non-linear capacitor which shunts the switch and the primary winding. An electrical connection is provided between a secondary winding of the pulse transformer and lamp connection terminals. The non-linear characteristic of the capacitor results in a more reproducible amplitude of the generated ignition voltage pulse.

Abstract: A dimmable fluorescent lamp including a feedback circuit for drawing sufficient current to maintain an appropriate charge across the buffer capacitor. A bypass capacitor provides a path for diverting a portion of the power which would otherwise be fed back to the buffer capacitor during low level dimming. Consequently, overboost voltages across the buffer capacitor during low level dimming are substantially reduced.

Abstract: A compact fluorescent lamp includes a ballast having a control circuit. The control circuit regulates the amount of power supplied to the lamp based on samples representing lamp current and lamp voltage. The sample of lamp voltage supplied to the control circuit is limited so that it cannot drop below a minimum level thereby preventing excessive levels of current from flowing through the lamp at low lamp voltage.

Abstract: A circuit arrangement including a DC/AC converter for operating a discharge lamp. The DC/AC converter includes input terminals for connection of the DC/AC converter to a DC voltage source, and a switching circuit connected to the input terminals and provided with at least one switching element. The switching element has a control electrode and a main electrode and a control circuit between the main electrode and the control electrode for generating a control signal for the switching element. The switching element is conductive when a voltage is present between the control electrode and the main electrode with a first polarity having a value which exceeds a threshold value. A load branch includes at least inductive means and output terminals for connection of the discharge lamp, which load branch is supplied via the switching circuit. The control circuit also generates a DC voltage component between the control electrode and the main electrode with a polarity which is opposed to the first polarity.

Abstract: The invention relates to an electromotor comprising a stator part and a rotor part, which parts form an oil-containing spiral groove bearing system. Surface areas of said parts are provided with a so-called oil barrier in order to prevent the oil from creeping from the bearing system to the environment. According to the present invention, said oil barrier comprises a monolayer of perfluorocarboxylic acid anions, especially those having a chain length of 10-20 C-atoms and/or perfluoroalkylthiol anions. Oil barriers of this type can be easily provided on the rotor part and stator part by means of dipping. These oil barriers have a very small thickness and can very suitably be used to prevent oil creepage.

Abstract: A random multiple path tabular routing method for routing data packets within a wireless, packet-hopping network, e.g., an intelligent lighting control system, which includes the steps of programming a plurality of the individual nodes to each serve as a repeater node for at least one other individual node, the repeater nodes forming multiple programmed communication paths between the central node and each of at least selected ones of the individual nodes, and randomly hopping the data packets along the programmed communication paths. The repeater nodes are preferably programmed on the basis of nodal connectivity information obtained during a network initialization process. The repeater nodes are preferably programmed by storing compact partial routing tables in a memory portion of each of these repeater nodes.

Abstract: A light source including a ballast characterized by a resonant frequency and including a reference bus and a transformer having a secondary winding. The fluorescent lamp is partially covered by a shield, connected to the reference bus and coupled to the secondary winding. The ballast further includes a current sensor connected between the secondary winding and reference bus for sensing current flow through at least the lamp including that portion of lamp current attributable to parasitic capacitances affecting the resonant frequency.

Abstract: An unreliability detector apparatus for generating an unreliable decision signal in response to an input signal. An input terminal receives the input signal, a first comparator unit compares the input signal with a first threshold value and a second comparator unit compares the input signal with a second threshold value. A processor is provided for carrying out a function for determining whether a curve in an X-Y plane has at least one point in common with a predetermined line in the X-Y plane. The curve in the X-Y plane is obtained by plotting time equivalent signals values of the first and second comparator output signals along the Y- and X-axis respectively of the X-Y plane, while the predetermined line in the X-Y plane is formed by a first line interconnecting a first fixed point and a second fixed point and in which half plane a third fixed point is located. The three fixed points are obtained by plotting combinations of a first through a fourth signal value along the X- and Y-axis.

Abstract: A circuit arrangement for operating a discharge lamp comprises a self-oscillating DC/AC converter (II) provided with a series arrangement of a first and a second switching element between a first and a second input terminal (2, 2') for connection to a DC voltage source (III). The series arrangement supplies an alternating current Ib to a load branch having output terminals for connection of the discharge lamp during nominal operation. The circuit arrangement is in addition provided with a starter circuit ST for generating a DC voltage component between the control electrode (1c') and the main electrode (1a') of the second switching element (1'). The starter circuit also include apparatus which comprise an auxiliary switch (25) that brings the first switching element (1) into a conducting state if the amplitude of the alternating current Ib is low compared with its amplitude during nominal operation.

Abstract: A piezo-electric transformer comprising a piezo-electric body (PEB) including a driving region having input electrodes (1, 3) and at least one driven region having output electrodes (E11). These regions have opposite faces with at least one of the regions comprising a number of sections polarized in a direction perpendicular to the opposite faces and one pole of each section being connected to an opposite pole of another section by electrically conductive elements (2, 1', 2') in such a way that the sections form a series arrangement.These sections are in a very simple way effectively arranged in series, thereby increasing the input impedance of the piezo-electric transformer. Because the sections are polarized in opposing directions the electrically conductive elements can be of a very simple construction which do not require external conduction wires.

Abstract: A circuit arrangement for supplying a discharge lamp comprises a control circuit which is provided with an integrated circuit. Means for generating a signal which is a measure of the lamp voltage are coupled to one pin of the integrated circuit. The periodic switching of the integrated circuit between a first and a second state insures that the lamp voltage will not exceed a minimum admissible value and a maximum admissible value. The use of only one pin makes the integrated circuit simple and accordingly inexpensive, while in addition only a small number of external components is required.

Abstract: An arrangement for generating drive signals for a multi-phase d.c. motor having a plurality of windings, comprising a multi-phase inverter (10) which supplies the drive signals to the windings of the motor in a manner such that the windings are recurrently energized by the drive signals in a given sequence. At least one of the windings is not supplied with a drive signal at least during predetermined free periods. A phase detector (40) which, under control of the multi-phase inverter, samples the back-emf signals of these windings in order to obtain a phase-error signal. A low-pass filter (42) generates a control signal dependence upon the phase-error signal, and a controllable oscillator (44) generates a frequency signal whose frequency depends on the control signal. The timing of the multi-phase inverter drive signals supplied to the motor windings depends on the frequency signal. A phase-locked loop is formed by the multi-phase inverter, the phase detector, the low-pass filter and the oscillator.