Abstract: A transformer assembly (300) for use with an internal load (307) includes a transformer core (323) having a primary winding (405). A first electrode (303) and second electrode (319) are used for contacting an internal load (307). A secondary circuit is formed that includes the first electrode (303), the second electrode (319) and conductors (301,313, 317) positioned between the first electrode (303) and second electrode (319). The transformer assembly (300) is arranged so that the conductors (301, 313, 317) surround the primary winding (405), transformer core (323), the first electrode (301) and second electrode (319). The transformer assembly (300) may be used in an electrode furnace or other high current and voltage applications requiring high efficiency in a small package.

Abstract: A circuit arrangement for striking a discharge lamp, comprising: a drive apparatus, having an output adapted to provide a drive signal with a predeterminable frequency; an inverter, which is coupled to the output of the drive apparatus, and having an output adapted to provide a square-wave signal with a predeterminable duty factor; a load circuit, which is coupled to the output of the inverter and has at least one terminal for the discharge lamp, the load circuit comprising a lamp inductor, which is coupled in series between the output of the inverter and the at least one terminal for the discharge lamp; a first control loop with a first reference variable, a first manipulated variable and a first controlled variable, the first control loop having a first time constant; a second control loop with a second reference variable, an auxiliary manipulated variable and a second controlled variable, the second control loop having a second time constant; and a strike detection apparatus, which is adapted to detect str

Abstract: A series connected L-C resonant circuit is connected between a lamp electrode of a xenon arc lamp and chassis ground. The L-C circuit has the ability to store energy as well as act as an oscillator. Energized by an initial high voltage pulse to a xenon arc lamp, the L-C circuit extends the ‘tail’ of the initial high voltage pulse provided to ignite the xenon arc lamp with a train or series of high frequency oscillations, which gradually decay. This resonant ‘tail’ causes the plasma streamer in the lamp to remain in the ionized state for an extended time period, until current ramp to the lamp up occurs, resulting in highly reliable ignition of the xenon arc lamp.

Abstract: A light emitting device includes an electronic driver and a planar light emitting element. The driver is connected with a source and the light emitting element, where the light emitting element has an internal capacitance and is connected to the driver in such a way that the internal capacitance serves as a passive output filter of the driver.

Abstract: A system for luminance characterization of a luminaire includes a ballast coil and a multi-tap capacitor connected in series with the ballast coil. The multi-tap capacitor has a plurality of tap capacitors integrated into a capacitor housing. A plurality of switches are each coupled to one of the plurality of tap capacitors for selectively coupling the tap capacitors together to produce a multi-tap capacitance corresponding to a configuration of the plurality of switches. A lamp is connected in series with the multi-tap capacitor and the ballast coil. A photometer is located to measure light intensity of the lamp and to produce a lumen output measurement. A memory is used to store a database having a plurality of lumen output measurements, each corresponding to a multi-tap capacitance corresponding to all configurations of the plurality of switches.

Abstract: An electronic ballast for a lamp having a bridge circuit, includes at least one first switch and a second switch coupled between a connection for a supply voltage and a connection for a ground potential, a center point of the bridge circuit between the first switch and second switches; a first and a second connection for a lamp the first connection coupled to the center point; and a signal evaluation unit. The evaluation unit includes a first input coupled to a signal which is at the DC voltage level of the first connection, and second input coupled to a signal which is at the DC voltage level of the second connection, the DC voltage reference potential for the evaluation unit being designed to be variable within a value range which is greater than or equal to the ground potential and is less than or equal to the supply voltage potential.

Abstract: The instant invention relates to an HID ballast and lamp tester, which provides visual indication of failure of either the ballast or lamp by continuously monitoring the status of the HID lighting system. The HID ballast and lamp tester detects and utilizes the voltage difference between the open circuit voltage and the operating voltage of the ballast to trigger visual indication of the open circuit voltage output of the ballast when the HID lamp has failed. The tester circuit comprises the ballast source, a full wave bridge rectifier and filter capacitor circuit, a voltage divider network circuit, a trigger circuit of a diac bi-directional silicon switch and a light emitting diode.

Abstract: A method of generating an electrical discharge in a gas contained in a sealed enclosure. The method includes driving a helical coil resonator at an RF frequency to generate an RF electric-magnetic field sufficient to generate an electrical discharge in the high pressure gas. The electrical discharge produces an emission spectrum that may be spectroscopically analyzed to determine the composition and impurity content of the gas.

Abstract: In a discharge lamp lighting apparatus to light two discharge lamps, one terminal of the secondary side of a step-up transformer is connected to one terminal of each of the two discharge lamps, the other terminal of each of the two discharge lamps is connected, via each of two variable inductance elements, to one lamp current detecting unit, a signal of each lamp current detecting unit is connected to a lamp current control circuit, and an output signal from each lamp current control circuit is connected to each variable inductance element so as to vary the inductance of each variable inductance element, whereby the lamp current flowing through each discharge lamp is controlled.

Abstract: An apparatus for providing power to a gas discharge lamp comprises a storage capacitor and an ignition switch coupled through a primarily parasitic first inductor to a parallel combination of a diode assembly and a second inductor in series with a gas discharge lamp. The second inductor is selected to optimize the energy transfer from the capacitor to the gas discharge lamp. During a first interval determined by the time constant of the series combination of a storage capacitor, a first inductor, and a second inductor, the diode assembly is not conducting and a forward sense current builds in the first and second inductors.

Abstract: The invention provides a power supply or drive circuit for a pulsed flashlamp which utilizes a two-core component having common windings as both an inductor for arc mode drive and for breakdown triggering of the lamp. Discharge of a capacitor through the inductor and lamp is controlled by a high-speed semiconductor switch which is turned on and off by a suitable control, current flowing from the inductor through a one-way path including the lamp when the switch is off. The control maintains the ratio of the power variation through the lamp to the average power through the lamp substantially constant. The controls may also be utilized to control output pulse shape. Novel protective features are also provided for circuit components during turn on periods for the switch.

Abstract: A method an apparatus for efficiently driving a low-voltage device from a wide-range input supply uses and inductor and a diode coupled in parallel to provide a high-efficiency energy storage circuit. The parallel diode/inductor circuit is coupled to a switch for intermittently supplying a current to maintain a level of energy storage in the circuit. The switch is coupled to a control circuit for controlling the switch. The external device be a relay and the inductor may be a coil of the relay. The external device may be one or more LEDs connected in series and the diode may be the series LED circuit. The control circuit may include a fault-tolerant synchronization input for connection to multiple driver circuits, whereby audible noise produced by beat frequencies between the relays is eliminated.

Abstract: A circuit arrangement and control thereof for igniting a high intensity discharge lamp, for reducing current stresses imposed on semiconductor devices during a polarity transition of a lamp voltage or lamp current, and for maintaining a parasitic current within an envelope of a square wave lamp current. A high frequency ignition voltage is only applied to the lamp during a starting operation. After the lamp breaks down in the starting operation, an imbalanced high frequency current flows through the lamp to assist a glow-to-arc transition. The high discharge current of the buck filter capacitor that is generally applied to the semiconductor devices during the polarity transition of the lamp voltage or lamp current, due to lamp extinguishing, is reduced. The lamp current is maintained as a low frequency square wave. Any spikes that may occur at the polarity transition of the lamp voltage or lamp current are superimposed on the lamp current within the envelope of the low frequency square wave lamp current.

Abstract: An electronic operating device for discharge lamps is disclosed in which an output terminal is connected via a coupling capacitor (CB) to a reference potential (E). An electric component (VC) which acts as a voltage source is inserted in series with the coupling capacitor (CB) in order to reduce the potential of an output terminal. The electric component (VC) consists in one embodiment of an inductor which is coupled to the lamp inductor.

Abstract: A circuit arrangement and control thereof for igniting a high intensity discharge (HID) lamp, for reducing the variation of the resonant ignition voltage under the parasitic capacitive loading condition, and for increased circuit stability. The high frequency ignition voltage is only applied to the lamp during an ignition phase. The variation of the magnitude of the resonant ignition voltage with respect to the parasitic capacitance at the lamp leads is minimized by inserting a damping resistor in series with the ignition resonant capacitor. In a normal operation after ignition, the charge and/or discharge current of the ignition resonant capacitor is bypassed through a bypass device instead of flowing through a current sense resistor, so that only a chopper current flows through a sensor by paralleling a relatively high impedance resistor with the sensor.

Abstract: A method for switching on an inductive load, in particular an ignition coil, whose current is intended repeatedly to reach a predefined variable end value at a respectively predefined variable time, includes measuring the time interval between the switching-on action and reaching at least one predefined intermediate value. This time interval and the at least one predefined intermediate value are used to calculate the anticipated time from switching on until the end value is reached. A following switching-on action is carried out at the calculated time before the respectively predefined time.

Abstract: A novel circuit for driving a high intensity discharge (HID) lamp uses pulse width modulation (PWM) switches to generate a signal to be delivered to a HID lamp. During different portions of the operating cycle, the system uses one switch to facilitate all PWM signaling, while the circuit uses two switching switches to generate the PWM signaling during other portions of the cycle operation.

Abstract: A circuit arrangement comprises four controllable switches (S1, S4) interconnected to form a full bridge. A warm-up operation is carried out in which there is a switch over between the two bridge diagonals (S1, S4; S2, S3) respectively. The gas discharge lamp (EL) is ignited by way of a series resonant circuit (L1, C1) which is coupled to the bridge branch. The actual normal operation is effected by switching over at a low frequency between the switches of the two bridge diagonals (S1, S4; S2, S3), with, moreover, one switch (S1, S2) of the respectively activated bridge diagonal being switched on and off alternately at a high frequency, with this switch (S1, S2) being switched on at the high frequency whenever the current (iL2) flowing by way of the bridge branch has reached a minimum value.

Abstract: An electronic operating device for discharge lamps is disclosed in which an output terminal is connected via a coupling capacitor (CB) to a reference potential (E). An electric component (VC) which acts as a voltage source is inserted in series with the coupling capacitor (CB) in order to reduce the potential of an output terminal. The electric component (VC) consists in one embodiment of an inductor which is coupled to the lamp inductor.

Abstract: The invention relates to a high-pressure discharge lamp having a base at one end and whose return conductor (13) is protected with the aid of a bidirectional trigger (D) against high induced voltages of the radio interference suppression reactor (L1) connected to the return conductor (13).

Abstract: Disclosed is inductive coupling of power to devices having negative resistances, such as gas-filled discharge lamps (fluorescent tubes, neon signs, and the like) from a primary inductive loop, using resonant conditioning of the power provided to the device. A “C” shaped inductor (202) around the loop and a resonating capacitor (406) in parallel with the inductor provide a current source to the lamp (403) from across the capacitor. The circuit is capable of first igniting a lamp using a higher voltage available when the Q of the unloaded circuit is high, then running the lamp or other device at a controlled current. The lamp current is substantially proportional to the primary inductive loop flux, and substantially independent of the lamp resistance. A second inductor (404) in series with the first though not itself a collector of flux acts as a current limit. Applications include lighting, displays (optionally isolated and dimmable), and production of ultraviolet radiation.

Abstract: The present invention provides a discharge lamp lighting system in which a discharge lamp is lighted by a commercial power source without using a choke transformer, electric power can be saved, and, in order to prevent a bad influence of high harmonic waves generated from the discharge lamp upon other electronic equipment, the impedance ratio resonating with the third high harmonic wave component of the power source is established between a capacitor and a choke coil provided between the discharge lamp and an alternate current power source to facilitate resonance of the third high harmonic wave component, and, when a starting lighting circuit is temporarily turned ON, the discharge lamp is lighted.

Abstract: An electronic flash device includes a first DC--DC converter circuit of separately-excited type, a second DC--DC converter circuit of separately-excited type, a capacitor to be charged by the first DC--DC converter circuit and the second DC--DC converter circuit, and a discharge tube which converts charging energy charged to the capacitor into light energy. The first DC--DC converter circuit includes a first switching element having a first control electrode, and an a first oscillation transformer to which energization is controlled by the first switching element. A first control pulse signal is supplied to the first control electrode. The second DC--DC converter circuit includes a second switching element having a second control electrode, and an a second oscillation transformer to which energization is controlled by the second switching element. A second control pulse signal is supplied to the second control electrode.

Abstract: An internal combustion engine-driven discharge lamp lighting apparatus including an internal combustion engine and a generator driven by the internal combustion engine to generate an output voltage and capable of lighting a high-voltage discharge lamp such as a high-voltage mercury lamp, a metal halide lamp or the like without using any ballast including a leakage transformer, to thereby eliminate problems due to incorporation of the ballast therein.

Abstract: A ballast circuit for a gas discharge lamp comprises a resonant load circuit incorporating the gas discharge lamp and including a resonant inductance and a resonant capacitance. A d.c.-to-a.c. converter circuit induces an a.c. current in the resonant load circuit. The converter circuit comprises first and second converter switches serially connected in the foregoing order between a bus conductor at a d.c. voltage and a reference conductor, and being connected together at a common node through which the a.c. load current flows. The first and second converter switches comprise respective interconnected control nodes respective reference nodes interconnected together at a common node. The voltage between each control node and associated reference node determining the conduction state of the associated switch. A voltage-limited energy source is connected between first and second nodes.

Abstract: Disclosed is a ballast circuit for a gas discharge lamp comprising a resonant load circuit incorporating the gas discharge lamp, a resonant inductance, and a resonant capacitance. A d.c.-to-a.c. converter circuit induces an a.c. current in the load circuit, and comprises first and second converter switches serially connected in the foregoing order between a bus conductor at a d.c. voltage and a reference conductor. The switches are connected together at a common node through which the a.c. load current flows. The switches each have a control node and a reference node, the voltage between such nodes determining the conduction state of the associated switch. The respective control nodes of the switches are interconnected, and the respective reference nodes of the switches are connected together at the common node.

Abstract: To provide for effective control of a discharge lamp, typically, a sodium gh pressure discharge lamp, which operates in two phases, namely, a power pulse phase, followed by a holding phase, without extensive and complex electronic circuitry, two individual oscillator systems are provided, one for each phase; the oscillator systems include a first power burst oscillator formed as a first half bridge by two transistors (T1, T2), and an individual connecting current limiting inductance (L1) to the lamp (E), and a second oscillator including a two-transistor second half bridge (T3, T4) and an individual current limiting inductance (L2) coupled to the lamp. The respective oscillators are controlled, in a closed control loop, by a burst generator (BG) and a holding pulse generator (SG), each of which provide their signals to a logic circuit (LK) which provides for exclusive control of the respective first or second half bridge.

Abstract: An inverter driving scheme for detecting when an inverter is in or near a capacitive mode of operation. In response to being within a capacitive mode of operation, the switching frequency is immediately increased to its maximum setting. When a near capacitive mode of operation is detected, the switching frequency is increased at a preset rate. During overvoltage conditions across the lamp combined with a near capacitive mode of operation, the switching frequency is immediately increased to its maximum setting.

Abstract: A power supply circuit for a fluorescent lamp. The circuit includes a switching power supply, such as a square wave switching power supply and a load current smoothing capacitor. A fluorescent tube is connected between the switching power supply and the load current smoothing capacitor. A linking connection from the switching power supply to a main voltage supply includes a rectifier. A first diode is connected between the rectifier and the linking connection, while a second diode is connected between the load current smoothing capacitor and the load. A single current path to the load current smoothing capacitor is defined through the second diode, while a single current discharge path from the load current smoothing capacitor is defined through the first diode. Two stabilizing capacitors are provided that are connected across the switching power supply to stabilize the duty cycle of the power supply circuit, with the load being located between the two stabilizing capacitors.

Abstract: The light output of an electroluminescent panel is increased by using resonant transformation to increase the operating voltage across the panel to a level greater than the source or input voltage. This is accomplished by connecting the electroluminescent panel into a series resonant circuit whose capacitance value is made up at least in part of the intrinsic capacitance of the electroluminescent panel itself, and by choosing the inductance and capacitance values of the series resonant circuit to produce the desired output voltage across the electroluminescent panel. The resulting circuit is simple and low in cost, does not significantly add to the operating losses of the system, and takes advantage of the intrinsic capacitance of the panel in providing the desired resonant transformation.

Abstract: In an electronic ballast, a half-bridge inverter is powered from a DC voltage and provides a nominal 30 kHz square-wave-like inverter output voltage. The inverter output voltage is applied to a series-resonant LC circuit. Parallel-connected across the tank capacitor of this LC circuit are plural series-combinations, each consisting of an instant-start fluorescent lamp series-connected with a current-limiting capacitor. The magnitude of the high-frequency voltage present across the tank capacitor is controlled by controlling the frequency of the inverter output voltage. Prior to lamp ignition, the magnitude of the high-frequency voltage is controlled to a relatively high level, such as to provide for sufficiently forceful lamp ignition. After the lamps have fully ignited, to enhance overall efficiency, the magnitude of the high-frequency voltage is reduced to a relatively low level. This low level is too low to provide for lamp ignition but sufficiently high to permit proper lamp operation.

Abstract: An electrode-less high pressure discharge lamp has a lamp vessel which is surrounded by an electric coil having turns. End portions of the coil are electrically connected to current conductors. The turns of the coil are supported by aluminium nitride, which is in thermal contact with the current conductors. There is a good heat transfer from the coil to the conductors, keeping the coil relatively cool and efficient. The coil screens the lamp vessel to a small extent only, thereby improving the lamp efficacy.

Abstract: In a power-line-operated current-fed parallel-tuned electronic ballast, power-factor-correction and harmonics-reduction are attained by placing a high-frequency inductor as well as a high-frequeny voltage source in series with the DC output of a bridge rectifier connected with the power line voltage. The DC output is then supplied to a filter capacitor through a high-speed diode, thereby to provide a DC voltage of substantially constant magnitude to the ballast's inverter while at the same time drawing power from the power line with a power factor well over 90% and with a total harmonics content well under 20%. The AC voltage provided from the high-frequency voltage source, which has a peak-to-peak magnitude essentially equal to that of the power line voltage, is represented by a simple auxiliary winding on the ballast's main output transformer.

Abstract: In a fluorescent lamp ballast, a high-frequency AC voltage is applied directly across a tuned L-C circuit. The fluorescent lamp is connected in parallel with the capacitor of the L-C circuit and a voltage-limiting means prevents the series-resonating L-C circuit from overloading the source of AC voltage during any period when the lamp is not effective in providing circuit loading. When power is initially applied to the L-C circuit, a control means provides a short circuit across the capacitor; and, by way of a first current transformer, the resulting short circuit current is used for pre-heating the fluorescent lamp cathodes. After about 1.5 second, the control means provides for removal of the short circuit for a period of about 25 milli-seconds, thereby permitting the voltage across the capacitor to grow to a magnitude sufficient to ignite and operate the lamp, while at the same time removing the cathode voltage.

Abstract: A ballast circuit for a fluorescent lamp including a magnetic choke electrically connected between the lamp and a power supply and an electronic starter circuit electrically coupled across said lamp, which ballast circuit is configured to provide a power factor of at least 90%. To this end, for certain lamps a power factor correcting capacitance is electrically connected across the power supply. For other lamps, a power factor correcting resistance is coupled between the ballasting capacitance and inductor so that the inductor and ballasting capacitance close to resonance.

Abstract: A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current.

Abstract: To ensure ignition of a high-pressure discharge lamp, for example a metal vapor halogen high-pressure dicharge lamp which has an ignition circuit, and is operated by direct current from an inverter circuit controlled for pulse width modulation, current flow to the lamp is extended in time upon initial energization thereof so that an initial hot spot which forms on an electrode can remain hot to establish a stabilized arc. This extension of current flow can be obtained by an R/C circuit in parallel to the output or storage capacitor (C.sub.A) of the inverter circuit (FIG. 1) or by an NTC resistor (H) in series with the lamp, or by a resistor which is short-circuited by a relay contact as the lamp operates, or the like.

Abstract: The invention relates to an inverter powering a lamp that uses a switch to vary the resonance of the resonance circuit for starting and for operating.

Abstract: The method of igniting a gas-discharge lamp includes the steps of generating an exciting signal T in an operating circuit having an AC voltage generator on receipt of a lamp switch-on signal E by the operating circuit; exciting an ignition resonant circuit connected to a gas-discharge lamp with the exciting signal T to produce a decaying oscillating process, advantageously a decaying oscillating voltage, in the ignition resonant circuit; determining a resonant frequency of the ignition resonant circuit from the decaying oscillating voltage or process with a signal processing circuit, advantageously a microprocessor, connected to the ignition resonant circuit and operating the AC voltage generator at the determined resonant frequency by controlling the AC voltage generator with the signal processing circuit. The apparatus can be shut off or a warning signal generated when a predetermined parameter of the decaying oscillating process is exceeded.

Abstract: A high-pressure metal vapor discharge lamp comprises: an arc tube, which is shunted by a series circuit of a thermal switch and a nonlinear ceramic capacitor, a pyroelectric current bypassing resistor connected in parallel to the nonlinear ceramic capacitor, and a lamp outer bulb incorporating the arc tube, the thermal switch, the nonlinear ceramic capacitor and the resistor. Because of this construction, the nonlinear ceramic capacitor is prevented from early deterioration, thus lengthening the service life of the discharge lamp.

Abstract: A fluorescent lamp lighting apparatus comprising a DC power source, a pair of field-effect transistors which are connected in series to each other, in which drains and sources of these transistors are connected in series to each other, whereas gates are connected to an oscillator, a pair of voltage-dividing capacitors which are connected in parallel to the DC power source, and an inverter circuit having an insulative leakage transformer whose primary coil is connected to a contact between these field-effect transistors and also to the other contact between those capacitors. One-end of filaments of a fluorescent lamp are connected to both ends of the secondary coil of the leakage transformer, whereas a startup capacitor is connected between the other ends of the filaments.

Abstract: A circuit is disclosed which is capable of positively shifting a gas discharge lamp from its off-state to its on-state without emitting light flashes and further positively maintains the gas discharge lamp in its on-state when first ignited. The circuit contains an oscillator device which generates and supplies an oscillator signal of a specific oscillator frequency from two output terminals of the oscillator device. It also contains a current limiting device an a parallel-resonance circuit comprising a capacitor and an inductor. The parallel resonance circuit has a frequency of resonance substantially identical to the oscillator frequency. The current limiting device and parallel-resonance circuit are connected in a series configuration across the output terminals of the oscillator device. Further, the gas discharge lamp is connected across or in parallel with the parallel-resonance circuit.

Abstract: Ballast and starting circuits for controlling current and voltage applied to an electrical discharge lamp. The ballast circuits use diodes or other suitable means to divide the AC power into positive and negative currents. The ballast circuits use positive and negative capacitors which are charged by the divided AC line current. In some embodiments the positively charged capacitors are charged during positive portions of alternating current and discharged during negative portions of the alternating current. The negatively charged capacitors are charged during negative portions of the alternating current and discharged during positive portions. Transistors or other appropriate switching means are used to controllably conduct current from the positive and negative capacitors to the lamp in an asynchronous manner. Startup circuits are included for boosting the voltage applied to the lamp either manually or automatically upon startup.

Abstract: In a ballast circuit for producing a DC signal with a high voltage amplitude, a capacitor is connected to a circuit output. The capacitor stores a charge which provides the high voltage amplitude of the DC signal. Current from an inductor is used to charge the capacitor. A current gate, when it is turned on, drains current from the inductor. A control circuit turns the current gate on and off so that the amplitude of the current drawn from the incoming AC voltage signal is in phase with the amplitude of the voltage of the incoming AC voltage signal. The control circuit includes a ramp generator which generates a pulse modulation reference signal with a varying voltage amplitude and a comparator which compares the pulse modulation reference signal with the incoming AC voltage signal after the incoming AC voltage signal has been rectified and the voltage divided by a voltage divider. The comparator produces a first modulated signal.

Abstract: A DC/AC converter (8) having a half bridge circuit for igniting and feeding a gas and/or vapour discharge tube (1). A starting capacitor (94) of this converter is connected between a junction (A) between two branches--each comprising a semiconductor circuit element (60 and 61)--of the half bridge circuit on the one hand and a center tapping (E) of a voltage divider (90, 91) on the other hand. As a result, the converter (8) starts satisfactorily and hence the discharge tube (1) readily ignites, moreover undesired starting pulses during the operating condition are avoided.

Abstract: In a method or combination, a DC voltage supply, a converter including a series or a parallel resonant circuit for converting the DC voltage to a sinusoidal current, and a load including at least one fluorescent lamp responsive to the sinusoidal current to effect excitation of the lamp.

Abstract: A switching arrangement suitable for the ignition and operation of at least one high-pressure discharge lamp, which arrangement is provided with a branch comprising a capacitor parallel to the lamp. The capacitor is also connected to a charge voltage source. The branch comprising a capacitor includes a gas-filled breakdown element. During ignition of the lamp current can be supplied from the capacitor to the lamp, while in the operating condition of the lamp the capacitor is switched off.

Abstract: A DC-AC converter for supplying energy to a dishcarge lamp (17). The converter is in the form of an imcomplete half-bridge circuit (11, 12; 15, 16, 19, 18). The lamp (17) is connected in series with a coil (18) and a capacitor (16). Two switching elements (11, 12) in the half-bridge circuit are formed as semiconductor switching elements. The lamp current is a square-shaped alternating current. A diode (13) is connected in parallel with the one switching element (11) and a diode (14) is connected in parallel with the other switching element (12). The control circuit of the switching elements is provided with a switching circuit (21) which alternately switches the one switching element (11) and the other switching element (12) several times. The number of switching elements through which the lamp current flows can therefore remain limited to two.

Abstract: An apparatus for starting and operating a discharge lamp includes an inverter circuit. The inverter circuit comprises a parallel resonance circuit including an oscillation coil and capacitor, and which is connected to the discharge lamp, via a current-limiting coil, a switching transistor for triggering the parallel resonance circuit, and a feedback circuit connected to the switching transistor, for allowing a feedback signal for driving the switching transistor to be supplied to the base of the switching transistor, the feedback circuit being magnetically coupled to the current-limiting coil.

Abstract: A hybrid ballast apparatus for starting and operating a plurality of series-connected discharge lamps and which provides protection against electric shock. The ballast apparatus includes first and second bidirectional thyristors connected in parallel with first and second ones of said lamps, respectively, and a trigger control circuit for simultaneously triggering the thyristors into conduction. Each lamp has two filaments and means are provided for connecting an L-C ballast device, the lamp filaments and the first and second thyristors in a series circuit across the AC supply voltage terminals. If one end of a lamp is removed from its socket, the series circuit is opened so that the maximum voltage at any lamp electrodes is limited to the AC supply voltage.