Abstract: A fluorescent lamp ignition circuit of the type including a DC voltage stabilizer to process input voltage into a constant voltage by dropping or boosting, an inductance filter to receive output power supply from the DC voltage stabilizer and to remove surge from it, an oscillator having a transformer, which receives output power supply from the inductance filter and then provides a sin-wave output for igniting a fluorescent lamp, and a feedback circuit connected between the oscillator and the fluorescent lamp to provide a feedback signal to the DC voltage stabilizer, wherein the feedback circuit includes two shunt resistors, which connect the mid-point of the secondary side of the transformer of the oscillator to earth, and two diodes respectively connected between the shunt resistors and the DC voltage stabilizer to form a double-feedback loop.

Abstract: Disclosed is a lighting circuit for a discharge lamp, which employs a rectangular-wave based lighting system and is designed to prevent lighting failure from frequently occurring in the discharge lamp immediately after the lighting of the discharge lamp starts or at the end of the lamp's life. In the lighting circuit, a battery voltage is boosted by a DC booster circuit and is then converted to a rectangular-wave voltage by a DC/AC converter. This rectangular-wave voltage is then applied via an inductor of an igniter circuit to a metal halide lamp. The DC booster circuit has a chopper type structure and has a smoothing capacitor at the output stage. A resonance controller comprising a diode and a resonance capacitor is located between the DC booster circuit and the DC/AC converter. The DC/AC converter has a bridge structure having field effect transistors (FETs). The two pairs of FETs are reciprocally switched from one pair to the other by a drive controller.

Abstract: A half-bridge inverter is powered from a constant-magnitude DC supply voltage and provides at the inverter's output a first AC output voltage that is describable as a modified squarewave voltage. This first AC voltage is applied across a series-combination of an inductor and a capacitor, the junction between which is clamped to the DC supply voltage. As a result, a second AC voltage gets established across the capacitor; which second AC voltage is also describable as being a modified squarewave voltage. However, the phasing of the second AC voltage is delayed by approximately 90 degrees with respect to the first AC voltage; which results in the voltage across the inductor being of approximately sinusoidal waveform. A fluorescent lamp is connected in series with a ballast capacitor; and the lamp-capacitor series combination is connected across the inductor, thereby resulting in a nearly sinusoidal current being provided to the fluorescent lamp.

Abstract: An electronic ballast has a high voltage portion and a low voltage portion. The high voltage portion includes a converter, having a variable frequency boost circuit, and a half-bridge, driven inverter having a series resonant, direct coupled output. The low voltage portion of the ballast includes a control circuit and fault detectors for shutting off the boost circuit and the inverter circuit. The fault detectors consume very little power when the ballast and lamp are functioning normally. Separate magnetics are used for boost, inverter, and output. Each magnetic is essentially cubic in shape and carries as little current as possible.

Abstract: A gas discharge lamp power ballast or power supply having simplified power factor correction, simplified automatic short circuit/overload protection and output open circuit voltage regulation. The gas discharge power ballast or power supply includes self-oscillating converter circuitry to which simplified power factor correction is provided via simple passive circuitry that includes a split winding from the power transformer in conjunction with an input storage capacitor and a current limiting resistor. The short circuit/overload protection is implemented, without elaborate current sensing circuitry, by utilizing the drive winding of the power transformer. In a shorted or overloaded state, a capacitor interacting with oscillator circuitry, controls oscillator cycling to reduce current flow and protect the circuitry against the overload at the output. Output open circuit voltage regulation and power regulation are also implemented in a simplified manner without the need for significant additional circuitry.

Abstract: A discharge lamp lighting apparatus includes a voltage raising element for raising a DC input voltage, a pulse generator for varying the output voltage output by the voltage raising element is a pulse voltage having a given pulse width and outputting the pulse voltage, a bridge circuit for applying the pulse voltage to a discharge lamp, a voltage detecting element for detecting a voltage applied to the discharge lamp, a current detecting element for detecting a current running through the discharge lamp, an adder for adding a first amplification signal output by a first amplifier and a second amplification signal output by a second amplifier together, elements for delaying outputs from the amplifiers, and a pulse width modulator for controlling the pulse width of the pulse voltage.

Abstract: A compact folded fluorescent lamp and a small incandescent lamp are both mounted on an ordinary Edison-type screw-base capable of being screwed into an ordinary lamp socket at which ordinary AC power line voltage is controllably provided. An inverter-type ballast is integrally combined with the base and is operable to power the fluorescent lamp whenever the base is indeed screwed into the lamp socket. The incandescent lamp is powered from the AC power line voltage by way of an SCR whose conduction angle is controlled such as to cause the total light provided from the combination fluorescent-incandescent lamp to remain substantially constant from the very first moment that AC power line voltage is provided at the lamp socket. Thus, when the AC power line voltage is initially provided, the light provided from the incandescent lamp will be at its maximum while the light provided from the fluorescent lamp will be at its minimum.

Abstract: A lighting device for a high-pressure discharge lamp includes an inverter circuit for converting a DC voltage into an AC voltage using a pair of switching elements. The switching elements have a switching frequency for starting the high-pressure discharge lamp that is higher than a resonance frequency of a series resonance circuit connected in parallel with the discharge lamp. However, in a lighted state of the discharge lamp, the switching frequency is lower than the resonance frequency of the resonance circuit and is within a frequency range where acoustic resonance does not occur. The lighted state of the high-pressure discharge lamp is maintained by a voltage across a capacitor in the series resonance circuit.

Abstract: Ballasting system for fluorescent lamps having improved energy transfer capability and which delivers a sinusoidal current waveform free of high order harmonics and induces a similar waveform into the power distribution system. The system includes a low leakage reactance auto-transformer which is tuned to the line frequency, and a separately-wound heating transformer and means for switching energy from the heating transformer each half cycle.

Abstract: A lighting circuit reduces the chance of shifting the generation timing for a start pulse with respect to the polarity of a rectangular wave. The lighting circuit has a start pulse generator which is designed to generate a start pulse only when the rectangular wave voltage obtained by a DC-AC converter has a certain polarity. A lighting discriminating circuit discriminates the ON status or OFF status of a discharge lamp. A lighting frequency controller is provided to alter the lighting frequency so that the frequency of the rectangular wave output from the DC-AC converter when the OFF status of the discharge lamp is discriminated becomes lower than the frequency of the rectangular wave output from the DC-AC converter when the ON status of the discharge lamp is discriminated.

Abstract: A ballast circuit for a gas discharge lamp, of the type having a pair of resistively heated cathodes that are resistively heated both during a cathode pre-heat period prior to lamp turn-on, and during steady state lamp operation, is disclosed. The ballast circuit includes circuitry for providing, on a bus conductor, a d.c. bus voltage with respect to a ground, and a converter, responsive to the d.c. bus voltage, for supplying bidirectional current to a resonant load circuit. The resonant load circuit includes the gas discharge lamp, a resonant capacitor coupled between the lamp cathodes such that its voltage varies with lamp voltage, and a resonant inductor serially coupled to the resonant capacitor and cooperating therewith to set a magnitude, and resonant frequency, of the bidirectional lamp current. Circuitry is provided for powering the resistively heated lamp cathodes, to thereby heat the cathodes.

Abstract: Controlled DC supply voltage is provided to a self-oscillating FET bridge inverter ballast from a pre-converter and by way of an inductor having two separate windings on a common magnetic core--with one winding being positioned in each leg of the DC supply. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the bridge inverter's output, thereby providing a special AC output voltage thereat. This special AC output voltage is characterized in that it exhibits an unusually high rate of voltage change at its cross-over points but otherwise has a substantially sinusoidal waveshape. An instant-start fluorescent lamp is connected via a current-limiting capacitor across the bridge inverter's output. The magnitude of the DC supply voltage is so chosen as to cause the magnitude of the AC output voltage to be such as to effectuate proper instant-starting of the fluorescent lamp. Because the AC output voltage is balanced with respect to ground, U.L.

Abstract: An inverter for the supply of one or more discharge lamps with heated electrodes includes a load circuit with a series resonant circuit and at least one lamp, two controllable switches and a control circuit for the switches, causing the switches to conduct alternately. A normally isolated dissipative component is connected, when the voltage across the load circuit exceeds a given value, to the load circuit, thus modifying its figure of merit to limit the maximum voltage without varying the resonant frequency of the load circuit.

Abstract: A power supply circuit (100) for use in driving fluorescent lamps (102, 104, 106) has a current mode control voltage boost IC (144) which produces a boosted voltage and has a power control input (pin 3) and a frequency control input (pin 4). The lamps are driven by a self oscillating inverter (178, 180, 196, 198) which is powered from the voltage boost IC and which operates at a frequency independent therefrom. In order to dim the lamps a D.C. bias voltage is applied to the power control input. At the same time a commensurate D.C. bias voltage is applied to the frequency control input so as to provide power factor correction in dependence on the power produced by the voltage boost IC. The circuit thus provides a substantially constant, optimum power factor at both full and dimmed light levels.

Abstract: A ballast circuit for driving fluorescent lamps characterized by a minimum of components has a power transformer constructed to present a source impedance integrated with the transformer and in series with the lamp load sufficient to regulate the load current to within 10% for a selected maximum wattage fluorescent lamp load, such as 18 or 36 watt, and any lesser fluorescent lamp loads. The transformer has a high voltage secondary winding with a reflected impedance at least 6.0 times greater than the reflected impedance of the selected worst case fluorescent lamp wattage load. The integrated magnetics design of this ballast also provides passive short circuit protection, filament current reduction after lamp strike, and cold temperature start-up with a minimum of circuit components.

Abstract: A lamp driving circuit having a series inductor and capacitor (L-C) in which the lamp load is connected in parallel with the capacitor. During pre-ignition of the lamp load, the driving signal supplied by a half-bridge oscillator includes a fundamental frequency and a third harmonic of the fundamental frequency. The resonant frequency of the series connected L-C circuit is at least .sqroot.5 times greater than the fundamental frequency but less than the third harmonic of the driving signal.

Abstract: An electronic supply for igniting and operating a high-pressure discharge lamp, comprising a first driven main switching device for generating a high-frequency current through an inductive element and a switching element suitable for subsequently supplying current through the inductive element when the first main switching device is non-conducting. The electronic supply is provided with a transformerless level shifter (LS) and with a driver circuit (S) comprising at least a switch drive device for driving the first driven main switching device. The switching element suitable for the subsequent current supply forms a part of a second driven main switching device which provides periodic commutation of the current through the inductive element, while the level shifter is free from any self-induction elements.

Abstract: A circuit arrangement for operating a discharge lamp, comprising a DC-AC converter provided with a branch comprising a series circuit of two switching elements, each switching element being shunted by a unidirectional element, while ends of the branch are provided with connection terminals suitable for connection to poles of a DC voltage source, a load branch comprising inductive means and lamp connection connection terminals suitable for accommodating a lamp, which load branch shunts one of the switching elements of branch. A first drive circuit I for generating a first drive signal during stationary lamp operation for rendering each of the switching elements in the branch alternately conducting and non-conducting, whereby each switching element is rendered conducting and non-conducting once in succession within a time interval during which the other switching element is non-conducting.

Abstract: An electronic ballast includes a triggered boost circuit, a driven inverter, and a low voltage signal generator in a a half-bridge, push-pull, series resonant, parallel loaded configuration. The boost circuit is triggered by a voltage from the inverter and the inverter is controlled by the low voltage signal generator. The boost circuit includes a low voltage output for powering the signal generator. In the event of a fault, the operation of the signal generator is interrupted, thereby shutting off the boost circuit and the inverter. A DC blocking capacitor is in series with the lamps and a resistor is connected in parallel with the DC blocking capacitor. The ballast is started by a pulse of displacement current through the lamp filaments to the boost circuit. Since the lamp filaments must be intact, the ballast does not begin a lamp starting sequence until lamps are connected to the ballast.

Abstract: To operate a low-pressure discharge lamp, typically a fluorescent lamp, from a low voltage source of, for example, between 5 and 24 V, two diodes (D1, D2) polarized to provide for current passage towards the lamp are connected between the output of a blocking oscillator and the lamp (L). At least one diode (D2) provides for preheating the lamp electrode. The other diode (D1) prevents immediate starting of the lamp; it is integrated in the circuit between the secondary winding (N2) of the blocking oscillator transformer (TR) and one lamp electrode (E1). The first diode (D2) is connected between the primary winding (N1) and the other terminal of the secondary winding (N2), and also to the other lamp electrode (E2). An additional capacitor (C4) connected, effectively, across the lamp (L) improves the starting of the lamp. The circuit is readily adaptable for association with a recharging circuit (FIG. 3) for recharging a rechargeable battery to supply the lamp.

Abstract: According to this invention, there is provided a method for starting a gas-conducting lamp, by which a gas-conducting lamp is started directly by a high-voltage without pre-heating of filament. Such a high-voltage is realized by an inductor-capator resonant circuit (LC resonant circuit) or a tap of an inductor. According to this invention, there is also provided a gas-conducting lamp for carring-out the abovementioned method. The method according to this invention is simple and effective and is adapted to the use of a gas-conducting lamp without filament or that with filament which has been broken or has failed.

Abstract: In a power-line-operated current-fed parallel-tuned electronic ballast, power-factor-correction and line current harmonics-reduction are attained by placing a high-frequency inductor as well as a high-frequency voltage source in series with the unfiltered DC output of a bridge rectifier connected with the power line voltage. The unfiltered DC output is then supplied to a filter capacitor through a phase-controlled field-effect transistor, thereby to provide a DC voltage of controllably 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%.

Abstract: Disclosed is a ballast circuit arrangement for a gas discharge lamp, which includes a ballast transformer arrangement receptive of an input power signal, having a winding and a serially connected ballast capacitor, and providing an output, ballast voltage that alternates in polarity during successive half cycles. A bypass capacitor is coupled to the winding of the ballast transformer for being charged by the ballast voltage. A voltage for driving the lamp exists on the bypass capacitor. The inventive arrangement includes a pulse transformer having a secondary winding in serial circuit with the lamp for impressing a high voltage, hot restrike starting pulse across the lamp. A hot restrike starting circuit is provided, comprising a starting capacitor coupled across the bypass capacitor, and a circuit for discharging the starting capacitor including a primary winding of the pulse transformer and a serially connected current switch.

Abstract: A power line-operated electronic converter is adapted to deliver a relatively constant magnitude high frequency signal to a load (113) and is operable to draw a substantially sinusoidal current from the AC voltage source (101). The converter has DC input terminals (V+, V-) having a capacitor (108) connected therebetween, rectifying bridge (103) and boosting rectifiers (D5,D6) coupled to the DC input terminals, a resonant oscillator circuit coupled to the DC input terminals and to the transistor inverter (106) employing two integrated and synchronized resonant circuits having two resonant capacitors (114,112) and one common resonant inductor (110) wherein one circuit is used to operate the load and the other to provide boosted pulsating DC voltage to be naturally added and integrated with the rectified voltage of the AC voltage source.

Abstract: The present invention relates to an inverter driven lamp arrangement. The arrangement provides for the sensing of both lamp voltage and current. The arrangement also provides for a large current during times of low voltage and a small current during times of high voltage. The sensing of lamp current is done by a current detector that is connected to a resonance circuit whose output is applied in signal form to a lamp start control circuit. The resonant circuit is a series connected resonant circuit composed of a choke coil and a first capacitor. This series connected arrangement is further connected in series with a second non-resonant capacitor. Also the arrangement includes circuitry to gradually reduce the frequency of the inverter just after the lamp starts.

Abstract: An energy efficient and cost effective electronic ballast circuit which lights a fluorescent tube but which avoids excessive voltages or pulsing of the tube. The starter circuit preheats the filaments for a time sufficient to ensure quick ignition upon application of an appropriate voltage, then ceases the flow of current after the tube is lighted to avoid wasting energy.

Abstract: The present invention relates to a gas discharge lamp lighting system in which a voltage source is provided for supplying an a.c. voltage across the lamp electrodes and, further, a source of stored d.c. voltage which is gated to the electrodes in synchronism with and additive to the a.c. voltage, in order to provide a resultant voltage across the electrodes of a magnitude sufficient to light the lamp.

Abstract: In an electronic ballast for Rapid-Start fluorescent lamps, each one of two of the four transistors in a full-bridge inverter is driven from a commercially available timer by way of simple diode-resistor parallel-combination. Each one of the other two transistors is driven directly from an auxiliary winding on the full-bridge inverter's power output transformer. The fluorescent lamps are series-connected with a current-limiting inductor to form a series-combination; which series-combination is connected across an output winding of the power output transformer. Heating voltage for each of the lamps' cathodes is obtained by way of two series-connected windings: one one the power output transformer and one on the current-limiting inductor. The magnitude of the resulting cathode heating voltage is substantially higher prior to lamp ignition as compared with after lamp ignition.

Abstract: A fluorescent lamp starter which includes: a series circuit to be connected to a power source for supplying an AC voltage, including a ballast and a fluorescent lamp equipped with electrodes; a transistor having a collector and an emitter connected through a diode between the electrodes on an opposite side of the fluorescent lamp in which the power source is not connected; a control voltage supply means having a resistance means and a capacitor, which are operated by a voltage between the collector and the emitter of the transistor; and a transistor base control means for switching the transistor by a total voltage of a part of a voltage generated in the resistance means of the control voltage supply means and a voltage generated in the capacitor thereof.

Abstract: The present invention provide a an electronic ballast for instant start gas discharge lamps that is designed with a limited number of components thereby enabling it to be produced relatively inexpensively and to be operated more efficiently and more reliably. The invention provides quasi-voltage fed, half-bridge parallel resonant inverter. This inverter exhibits a voltage output characteristic in which the output power is inversely proportional to the load. The invention instantly starts in any order the multi-parallel configured gas discharge lamps. This invention balances the output current. This permits increasing the resonant frequency of the inverter to values higher than 50 Khz while maintaining a low crest factor and high efficiency.

Abstract: Circuitry is disclosed for operating with no stroboscopic effects at least three fluorescent lamps connected to a single source of single phase alternating voltage. In order to suppress the stroboscopic effects, the first lamp circuit (1) is connected in the usual way to both conductors (S;Mp) of the source of single phase alternating voltage; a series oscillating circuit (4) composed of an inductive resistor (L) and a capacitor(C) is arranged in parallel to the first lamp circuit; the second lamp circuit (2) is connected between a conductor (S) of the source of single phase alternating voltage the point of connection (Vp) between the inductive resistor (L) and the capacitor of the series oscillating circuit (4); and the third lamp circuit (3) is connected between said point of connection (Vp) and the other conductor (Mp) of the source of single phase voltage.

Abstract: Power to a self-oscillating inverter ballast is supplied from a DC voltage source through an inductor means having two separate windings on a common magnetic core--with one winding being positioned in each leg of the power supply. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the inverter's output, thereby providing a sinusoidal voltage thereat. A fluorescent lamp is connected by way of a current-limiting capacitor with the inverter's output.

Abstract: The invention relates to a DC power supply utilizing DC to AC to DC conversion with pulse to pulse current mode IC controlled PWM modulation at an above-sonic repetition rate (e.g., 30 Khz) in a degenerative feedback loop to achieve output regulation.The powder supply, which includes a step-down transformer and a choke input LC filter, is designed for energizing a short-arc, lamp and provides glow to arc transition energization, regulated run energization, and igniter controls. Output regulation may be either of current or power and is based on using a current emulating the current flowing into the filter choke or using both the emulating current and a voltage sensed in a separate secondary winding of the transformer. A novel ramp generating circuit which preserves loop sensitivity at high power loads and a novel method of powering the controlling IC are also disclosed.

Abstract: A current-fed parallel-resonant self-oscillating electronic ballast includes four special switching devices, each serving the function of a single switching transistor in a full-bridge inverter. Each special switching device includes two series-connected field effect transistors synchronously gated via positive feedback of a sinusoidal output voltage. The reason for using two series-connected field-effect transistors in lieu of a single field-effect transistor of higher voltage rating relates to the fact that, for the DC supply voltages associated with certain electronic ballast circuits powered from commonly encountered power line voltages, field-effect transistors of lower voltage ratings (e.g., 400 Volt) are substantially lower in cost per-unit Volt-Ampere rating as compared with field-effect transistors of higher voltage ratings (e.g., 800 Volt).

Abstract: Two methods are disclosed for providing a warm-up or pre-heat period for a gas-discharge lighting system, such as a fluorescent light. One method provides current to the lamp for a predetermined period of time to heat the filaments therein without significant ionization of the lamp. The second method provides current to the lamp to heat the filaments without significant ionization of the lamp until the voltage across the filament reaches a predetermined voltage. After the lamp is pre-heated, the current is increased to ionize the lamp.

Abstract: A circuit arrangement for operating a discharge lamp by means of a high-frequency current includes a switching device for generating the high-frequency current from a supply voltage, a modulator for the substantially square-wave modulation of the amplitude of the high-frequency current at a modulation frequency f, and an apparatus (M) for limiting the interference with infrared systems caused by the discharge lamp. The limiting apparatus (M) comprise a circuit N for providing a gradual increase in the rate at which the amplitude of the high-frequency current decreases at the end of a square wave of the square-wave modulation. This provides a considerable reduction in the interference with infrared systems caused by a lamp operated by the circuit arrangement.

Abstract: An electronic ballast embodiment of the present invention comprises a half-bridge parallel-loaded series resonant converter (HB-PLSRC) circuit a load is connected across a resonating capacitor with DC blocking capacitors in each of two legs and in series with a resonating inductor. The combination is connected to the junction of two switches wired in series across a DC source input such that the resonant inductor and resonant capacitor are connected across one of the switches. A coordinated manipulation of the switches is then used to charge and discharge the resonant inductor and resonant capacitor are pumped in series resonance. Alternatively, the load is connected through an isolation transformer.

Abstract: A gas-discharge lighting system having an inductor and at least two capacitors in combination with a gas discharge lamp, the inductor and capacitors forming a resonant system, the resonant frequency thereof being dependent upon whether the lamp is nonionized or ionized. The lamp is operated by driving the lamp, inductor, and capacitor combination with a signal of a first polarity and inverting the polarity when the signal current transitions a predetermined current level. This repeated until the polarity of the signal remains of one polarity longer than a predetermined time, at which time the signal is inverted. This is repeated indefinitely. The predetermined length of time is one-half the inverse of a minimum frequency greater than the ionized resonant frequency.

Abstract: A circuit for controlling low wattage gas discharge lamps comprised of a inductive coupling device, e.g., a transformer, a switching transistor, a current sensor, a comparator receiving a signal from the current sensor and driving the switching transistor, and a protective clamp circuit. The primary winding of the inductive coupling device receives a DC voltage and is also connected to the transistor. The transistor allows current to flow through the primary winding causing energy to be stored therein until the current sensor signals the comparator that a first threshold has been reached, the comparator then turns the switching transistor off and the inductive coupling device then enter a fly-back mode where the stored energy is applied to the lamp for a set period of time. The transistor then turns back on and this process is repeated so that the lamp receives a high frequency alternating voltage.

Abstract: A pre-converter is connected with AC power line voltage and provides DC voltage across a pair of DC terminals. A current-limiting inductor, a self-oscillating parallel-resonant inverter, and a periodically activated FET switch are series-connected with one another across the DC terminals. The inverter provides a high-frequency (e.g., 20-30 kHz) substantially sinusoidal output voltage across its output terminals. Each of plural rapid-start fluorescent lamps is connected across the output terminals by way of a current-limiting capacitor. The magnitude of the resulting lamp current depends on the RMS magnitude of the output voltage. In turn, for a given load condition, this RMS magnitude depends on the average magnitude of the unidirectional current drawn by the inverter from the DC terminals; which average magnitude is determined by the ON/OFF duty-cycle of the FET switch. The FET switch is turned ON/OFF at twice the frequency of the inverter's output voltage.

Abstract: A pre-converter is connected with AC power line voltage and provides DC rail voltage to a current-fed self-oscillating FET bridge inverter ballast. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the bridge inverter's output, thereby providing a sinusoidal AC output voltage thereat. Each of several instant-start fluorescent lamps is connected via a current-limiting capacitor across the bridge inverter's output. The magnitude of the DC supply voltage is so chosen as to cause the magnitude of the AC output voltage to be such as to effectuate proper instant-starting of the fluorescent lamps. Each of the four FET's is driven by a sinusoidal AC voltage derived directly from a positive feedback winding on the tank-inductor of the L-C circuit. To enhance circuit efficiency, the absolute magnitude of the DC rail voltage is controlled to be just higher than the peak absolute magnitude of the AC power line voltage.

Abstract: A power factor corrected electronic ballast circuit uses two transformer components. An inductively coupled charge pump technique is used for power factor correction while the gates of the transistor switches are driven directly from a resonant inductor.

Abstract: A flashing lamp set includes a plurality of gas-filled filament bulbs (101) having respective rise-time constants which are different from each other, thereby providing different thermo-optical effects. When power is supplied, the lamps are illuminated in sequence for security purposes or for a decorative effect.

Abstract: A parallel resonant circuit for powering a gas discharge lamp achieves power factor correction by using a floating power supply having adjustable voltage and impedance level. The floating power supply is powered by a transformer and placed in series with the rectified AC power line.

Abstract: The invention relates to an electronic ballast for a discharge lamp, comprising a drive circuit supplying high-frequency current to the lamp and including two power switches (V1, V2) and control circuits therefor for controlling the power switches, such that the parallel half-waves of the lamp current pass through a first power switch (V1) and the reverse half-waves through a second power switch. Each power switch (V1; V2) is provided with its own, independently operating control circuit and each control circuit is provided with means (R1, R3, R8, R7) for sensing a current passing through and a voltage prevailing across the appropriate power switch (V1; V2) as well as with means (V3; V4) for controllably bringing the appropriate power switch (V1; V2) to a conducting state as a certain voltage prevails thereacross and to a non-conducting state as soon as a current passing therethrough reaches a certain threshold value (Ik; Ikl).

Abstract: An electronic high frequency supply, such as a lamp ballast, having a full-wave rectifier, a storage capacitor charged to a voltage greater than the peak of the rectifier output, and an isolating diode between the rectifier and the diode. An inverter is connected to the energy storage capacitor, and has a high frequency inductive load circuit connected between the inverter output and a junction between the isolating diode and the storage capacitor. A capacitor, connected to the junction in parallel with a series circuit formed by the isolating diode and storage capacitor, forms a high frequency resonance circuit with the inductive load circuit. Current is drawn from the rectifier only as a series of pulses at the inverter frequency. To minimize variation in the high frequency load current, the inverter frequency is varied according to a sensed parameter which varies during each cycle of the rectifier output.

Abstract: A power supply and control circuit is provided for driving a fluorescent lamp from a low voltage DC power source such as a battery. A DC-to-AC inverter coupled to a switching regulator converts low DC voltage into a higher AC voltage for driving the fluorescent lamp. The lamp is included in a feedback loop which includes a circuit for producing a feedback signal indicative of the magnitude of current conducted by the lamp. The feedback signal is applied to the switching regulator to produce in the lamp a regulated current and, hence, a regulated lamp intensity. The magnitude of the lamp current can be adjusted to enable the intensity of the fluorescent lamp to be smoothly and continuously varied (without "dead-spots" or "pop-on") over a chosen intensity range, including if desired, from substantially full OFF to full ON. A method for driving a fluorescent lamp from a low voltage DC power source is also provided.

Abstract: A lead ballast circuit with power regulation for a gas discharge lamp includes an input pair of conductors for receiving an a.c. supply voltage, the magnitude of which voltage fluctuates within a known range. Further included is an output pair of conductors for supplying a driving voltage to the lamp. A lead inductor having a magnetic core and a lead capacitance serially connected to the lead inductor between an input, and an output, conductor are included. The inductive impedance of the lead inductor is less than the capacitive impedance of the lead capacitance whereby the aggregate impedance of the serially connected inductor and capacitance is capacitive rather than inductive. The lead ballast circuit also includes a power factor-correcting inductor connected across the input conductor pair, and having a magnetic core that shares a leg in common with the magnetic core of the lead inductor.

Abstract: In accordance with the invention, there is provided a ballast circuit for a gas discharge lamp. The circuit comprises means for providing a d.c. bus voltage on a bus conductor with respect to ground. The circuit includes a resonant load circuit incorporating a gas discharge lamp and including first and second resonant impedances whose values determine the operating frequency of the resonant load circuit. Further included is a converter circuit coupled to the resonant load circuit so as to impress a bidirectional voltage thereacross and thereby induce a bidirectional current in the resonant load circuit. The converter comprises first and second switches serially connected between the bus conductor and ground, and having a common node coupled to a first end of the resonant load circuit and through which the bidirectional load current flows. A current-sensing winding senses at least a portion of the current flowing in the resonant load circuit.

Abstract: An inverter-type electronic fluorescent lamp ballast normally powers a fluorescent lamp by way of a series-excited parallel-loaded resonant L-C circuit. During the lamp starting phase, as well as whenever the lamp is inoperative or not connected, inverter frequency is automatically increased substantially beyond resonance, thereby preventing circuit self-destruction which would otherwise probably result whenever an inverter is used for series-exciting an unloaded resonant L-C circuit.