Abstract: A ballast for a mercury-free, metal halide arc lamp having a quartz or fused silica envelope. The ballast provides a square-wave voltage, which substantially reduces or eliminates the re-ignition voltage in the mercury-free, metal halide arc lamp. The ballast reverses the voltage polarity, and reestablishes the arc current in the opposite direction, before the free halogen in the envelope can quench the arc.

Abstract: In an operating circuit for a low-pressure discharge lamp, the lamp current is controlled depending on the lamp temperature or the luminous flux.

Abstract: A ballast for operating different types of lamp loads through identification of the lamp type during steady state operation of the lamp load. Lamp type recognition is achieved based on a comparison of the lamp load voltage and lamp load current data points stored in a random-access memory of a microprocessor to a plurality of V-I characteristic curves stored in a read-only memory of the microprocessor. Through this comparison, the ballast can distinguish among a number of different lamp loads having the same starting voltage.

Abstract: A ballast for a compact fluorescent lamp includes a down-converter for operating the lamp with a DC current during stable operation and a charge pump for igniting the lamp. The converter includes an inductor and a first series circuit of a first diodie and a first switching element. An output capacitor shunts the lap terminals. The charge pump includes a second series circuit of second diodie and a second switching element coupled to the lamp terminals with the second diode polarized to prevent the discharge of the output capacitor when the second switching element is conductive. The inductor cooperates with the first and second diodes and the second switching element to build up the voltage across the outpout capacitor to the ignition voltage level of the lamp.

Abstract: In a ballast for parallel operation of discharge lamps in potentially explosive areas, an inverter is provided which has a branch which is assigned to the two discharge lamps, and in this respect is used twice. Two lamp-specific branches can be switched off separately if a fault occurs at the assigned discharge lamp.

Abstract: Control device (3) for the operation of a load, in particular at least one gas discharge lamp (10, 15). The control device (3) is divided into a first purely software controlled control unit (3a) a second control unit (3b) realized purely in hardware. The two control units (3a, 3b) are connected with one another via a bidirectional connection line, the second control unit receiving exclusively internal operating state information (I.sub.intern) and the first control unit (3a) receiving external control information (I.sub.extern) By means of the division of the control device into a purely software controlled control unit (3a) and a control unit constructed purely of hardware (3b) the control device (3) in accordance with the invention has both a speed sufficient for rapid control procedures and also a sufficient flexibility with regard to alterations. Advantageously, the control device (3) in accordance with the invention is employed in an electronic ballast for the operation of gas discharge lamps (10, 15).

Abstract: A circuit arrangement and method thereof for operating high intensity discharge (HID) lamps with a lower frequency rectangular current waveform, in which the frequency of the higher frequency ripple superimposed on the lower frequency rectangular current is modulated by a pseudo-random noise signal. The pseudo-random noise may be generated by a feedback shift register. The feedback shift register may incorporate run length interrupt logic to address PWM frequency stagnation by reducing the longest run length or lengths of the feedback shift register. The feedback shift register may also or alternatively include an RC low pass analog filter to address PWM frequency stagnation. The center frequency and frequency band of the pseudo-randomly generated noise may be adjustable.

Abstract: The circuit comprises a switched dc/dc converter of the "fly-back" type, a second switched dc/dc converter of the "feed-forward" type, an H-shaped bridge switching circuit which is connected to the dc/dc converters and in the central branch of which the discharge lamp and an associated reactive starter device are disposed, and a control circuit which can drive the dc/dc converters and the bridge switching circuit in a manner such that, each time the lamp is switched on, a very high voltage is applied initially, in particular, in order to start the lamp, and subsequently a low voltage is applied, but with a high electrical power, in order to support the passage of a large current through the lamp during the heating (warming-up) of the lamp and during the subsequent steady operation of the lamp.

Abstract: The invention relates to optimized-loss base drive for a bipolar transistor bridge oscillator circuit, by using base series capacitors and by not hng any non-reactive resistances in the base drive circuits.

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. In one embodiment, 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. In another embodiment, the lamp is symmetrically driven by isolating the lamp from the driving circuitry and indirectly deriving the feedback signal. 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.

Abstract: A power supply for a gas-discharge lamp includes a voltage source and drive circuit that produces an asymmetric output, a step-up transformer for stepping up the voltage to an appropriate level for driving the lamp, a blocking capacitor connected in series with the transformer and the lamp for preventing DC current from flowing through the transformer and the lamp to avoid core saturation of the transformer. A DC voltage is established across the lamp that prevents the formation of "bubbles" or "beads" in the gas discharge. An inverter is used to periodically reverse the polarity of the DC voltage to prevent mercury migration in mercury-containing lamps.

Abstract: A high-frequency power supply system for a plurality of fluorescent tubes includes an inverter type power supply connected to the primary side of the high-voltage transformer. The secondary side of the high-voltage transformer includes two high-voltage coils arranged to provide power to four hot cathode fluorescent tubes, wherein each of said high-voltage coils is connected to two of said hot cathode fluorescent tubes connected in parallel. The secondary side of the high-voltage transformer also includes supplemental coils arranged to heat filaments of the hot cathode fluorescent tubes. The power supply also includes at least one capacitor and at least one inductor connected to the secondary side and arranged in a manner that the secondary side provides power to a substantially resistive load.

Abstract: A device for lighting a discharge lamp comprises a rectifier, a switching circuit having a semiconductor element to be connected to said rectifier; a direct power supplying circuit having a rectifying circuit and filtering circuit each connected to said switching circuit; and a discharge lamp and a starter which are connected after said filtering circuit; said starter having a transformer and a smoothing capacitor for generating a high voltage is provided, which has a circuit having a switching element and a resistance connected in series provided between the smoothing capacitor and said discharge lamp and further has a second capacitor connected parallel to said discharge lamp.

Abstract: A low-voltage, high-efficiency signage system comprises a housing having a translucent indicia bearing panel member. A gas discharge lighting device inside the housing is driven from a source of a low-voltage, high-frequency square wave voltage source having a pair of output terminals. A coupling circuit which is not resonant at the high frequency connects the low-voltage, high-frequency square wave voltage to the gas discharge lighting device to non-thermionically start and operate the gas discharge lighting device, and thereby illuminate the translucent indicia bearing member from inside said housing. The low voltage is from about 2 volts to about 90 volts and the frequency is from about 75 kHz to about 3.5 MHz.

Abstract: A ballast for providing electrical energy to one or more fluorescent bulbs having electrical discharge filaments. The ballast includes a pre-heating circuit having a first resonant frequency, coupled to pre-heat the filaments. An electron-discharge circuit having a second resonant frequency is coupled to ignite an electrical discharge through a gas between the filaments. Driver circuitry provides power to the pre-heating and electron-discharge circuits in succession, so as to ignite the one or more bulbs. The driver circuitry first provides power to the pre-heating circuit substantially at the first resonant frequency and subsequently provides power to the electron-discharge circuit substantially at the second resonant frequency.

Abstract: In a power-line-operated high-frequency electronic ballast, a half-bridge inverter is powered from a DC supply voltage and a fluorescent lamp is connected with the inverter's more-or-less asymmetrical squarewave output voltage by way of a of a series-resonant L-C circuit. The amount of power supplied by the inverter to the series-resonant L-C circuit and/or to the fluorescent lamp at any given moment depends on four significant factors: (i) the instantaneous magnitude of the DC supply voltage, (ii) the instantaneous frequency of the inverter's squarewave output voltage, (iii) the symmetry of the inverter's squarewave output voltage (which determines the effective magnitude of of its fundamental frequency voltage component), and (iv) the instantaneous operational characteristics of the fluorescent lamp.

Abstract: A pulse generator for a stable output pulse voltage obtains a high voltage pulse with a charge accumulated in a capacitor and discharged at a discharge gap made ON, wherein a pulse energy source and a trigger source for conduction of the discharge gap are separately provided, so that the discharge gap will be conducted by a boosting action of the trigger source when a predetermined value is reached by a voltage of the pulse energy source.

Abstract: A ballast feedback scheme including a single stage current feedback inverter. To avoid overboosting of the voltage impressed across a buffer capacitor only a portion of the high frequency lamp current is fedback to the buffer capacitor during both ignition and steady state operation of the lamp. Ignition of the lamp is well controlled.

Abstract: A discharge lamp operating electronic device is provided with a booster circuit for converting the direct-current power provided by a direct-current power supply to a predetermined operating voltage, a self-excitatory inverter for converting the operating voltage provided by the booster circuit to predetermined high frequency, a lamp operating circuit for converting the high-frequency output from the self-excitatory inverter into sine waves to light a discharge lamp, an overload protective circuit for stopping an operation of the self-excitatory inverter circuit when an overload occurs in the lamp operating circuit. The operating efficiency of the filament of a hot-cathode discharge lamp is improved by alternately heating a thermionic discharge path from four points of the filament, and the voltage at the filament can be easily adjusted.

Abstract: A method for reducing the harmonics created by rapid-start fluorescent lamp stabilizer balance systems is accomplished by increasing the number of turns of the secondary winding of the transformer so as to decrease the secondary current to approximately 40 to 90 percent of the rated lamp current. This method increases the impedance and reduces the secondary current between 40 and 90 percent of the rated lamp current. While the absolute value of the illuminous intensity is lowered by the reduction in the secondary current, the lamp maintains a uniform brightness of illumination. This method decreases the distortion in the primary wave form which decreases the distortion effect on sensitive electronic systems which may be connected to the same electrical power source or may be in the area near the stabilizer.

Abstract: A circuit, such as a ballast circuit, includes a resonant feedback signal from an inverter that provides substantially linear operation of rectifying diodes. In one embodiment, capacitors coupled in series with respective lamps resonate with a first winding of a feedback transformer so as to generate a feedback signal on a second winding of the transformer. The feedback signal is effective to produce substantially linear operation of the rectifying diodes.

Abstract: The invention proposes an apparatus and method for operating a gas discharge lamp (10) contained in a resonant circuit (L1, C1). A series connection is provided that is connected to a voltage source (14) and comprises a first semiconductor switch (12), an inductive element (L2) and a second semiconductor switch (13), with the resonant circuit (L1, C1) being connected at a connecting point (15) between the inductive element and the second semiconductor switch (13). If the gas discharge lamp (10) is in the non-ignited state, the first semiconductor switch (12) is continuously switched on and the second semiconductor switch (13) is at least approximately switched with the resonant frequency of the resonant circuit (L1, C1). In the ignited state of the gas discharge lamp (10), the two semiconductor switches (12, 13) are switched alternatingly and in push-pull operation with the operating frequency for operating the gas discharge lamp (10) in continuous operation.

Abstract: An ignitor is provided to predictably and reliably start a conventional HID lamp, or to start or restart an HID lamp having a hot strike capability such as a high pressure xenon HPS lamp or similar lamp. The ignitor is configured to prevent the premature triggering of a semiconductor switch in a hot restrike circuit due to unwanted high voltage pulses generated by a conventional HID lamp starter circuit in the ignitor. An ignitor is provided that can be used with lag-type ballasts. Another ignitor is provided that can be used with a lead-type ballast which generates a DC bias across the ballast capacitor.

Abstract: A driving circuit of the present invention includes first and second piezoelectric transformers 12, 14 for outputting a voltage at a secondary terminal which is input from a primary terminal utilizing a piezoelectric effect, frequency control means 21 for outputting a frequency signal for operating the first piezoelectric transformer 12 at a required frequency voltage, phase reversing means 16 for reversing a phase of the frequency signal by 180 degrees, driving circuits 13, 15 for applying a frequency voltage to each of the piezoelectric transformers 12, 14 based on these frequency signals of which phases are different from each other by 180 degrees, a discharge tube 11 in which an output of the first piezoelectric transformer 12 is applied to a first input terminal and an output of the second piezoelectric transformer 14 is applied to a second input terminal, a circuit 20 for controlling a voltage of the first piezoelectric transformer 12 so that a current flowing in this discharge tube becomes to be consta

Abstract: A circuit arrangement for supplying a discharge lamp, comprising a converter for generating a high-frequency current with a frequency f from a supply voltage. The converter comprises at least one switching element which is rendered alternately conducting and non-conducting at the frequency f while the discharge lamp is being supplied. In addition a circuit portion I is provided for the low-frequency modulation of the power consumed by the discharge lamp through an adjustment of the conduction period of the switching element. As a result, instabilities in the discharge lamp plasma, such as striations and moding, are suppressed to a considerable degree.

Abstract: The invention relates to an inverter including an output regulating mechanism which is simplified in its construction and suitable for reduction of the manufacturing cost. The output regulating mechanism comprises a volume control adapted to be applied with an input voltage for said booster transformer periodically changing as the inverter oscillates, control means adapted to pulse-convert the output signal of the volume control and thereby to output a control signal which has been pulse width modulated according to the output signal of the volume control, and switching means provided on an input current path for the booster transformer so as to be turned ON and OFF with the control signal provided from the control means.

Abstract: A power supply circuit for discharge lamps having a load circuit with at least one discharge lamp and controlled switches with a switching control means which control the opening and closing of the switches to supply the load circuit with a high-frequency alternating signal. A recognition circuit, which recognizes the type of lamp connected to the load circuit by the power rating of the lamp, is provided. Control means which modify the switching conditions of the switches according to the type of lamp connected to the load circuit are also provided.

Abstract: A circuit for supplying a discharge lamp, comprising a converter for generating a high-frequency current at a frequency f from a supply voltage and a circuit portion I for adjusting the power consumed by the discharge lamp through adjustment of the frequency. The circuit portion I is provided with a circuit portion II for low-frequency square-wave modulation of the frequency f and for the adjustment of the duty cycle of the square-wave modulation. As a result, the discharge lamp can be dimmed over a very wide range without striations or moding occurring and without undesirable shifts in the color point of the light.

Abstract: A power supply circuit for a discharge lamp, in particular for a motor vehicle headlight, provides pulse starting. The circuit comprises a DC to AC converter giving an AC output at its secondary winding, together with a starting circuit which includes a transformer having a secondary winding in series with the discharge lamp. The apparatus further includes a branch which is connected in parallel with the secondary winding of the starter circuit transformer. At the frequency prevailing when an arc has been established in the discharge lamp, this branch has an impedance which is less than that of the secondary winding, so that the current then flows mainly in this branch.

Abstract: The invention provides a soft starter device for lamps. The soft starter device includes a rectifying circuit for converting an AC voltage into a DC voltage which serves as a triggering signal; a high frequency voltage generating circuit for generating a high frequency voltage by an oscillation between two transistors; a high frequency output transformer electrically connected to the high frequency voltage generating circuit and having a primary coil and a secondary coil; a first capacitor for providing a momently high voltage to a lamp tube by generating a resonance together with the high frequency output transformer; and a control circuit having a charging circuit and a switch for grounding the secondary coil connected thereto or allowing the secondary coil to function normally. At the initial time of power supplying, the switch is turned on to ground the secondary coil, causing the primary coil being not able to function, such that only a current flows into the lamp tube to preheat the filaments thereof.

Abstract: An object of the present invention is to effectively operate a discharging tube. A voltage raising unit and a discharging unit are disposed in a discharging tube. When a voltage is supplied to the discharging tube, the voltage raising unit raises the voltage to be supplied to the discharging tube. The raised voltage is supplied to the discharging unit. Thus, the discharging unit discharges electricity.

Abstract: A ballast circuit for a gas discharge lamp with high speed gate drive circuitry comprises a resonant load circuit including a resonant inductance, a resonant capacitance, and circuitry for connecting to a gas discharge lamp. A d.c.-to-a.c. converter circuit induces a.c. current in the load circuit, and comprises a pair of switches serially connected between a bus conductor at a d.c. voltage and a reference conductor, the voltage between a reference node and a control node of each switch determining the conduction state of the associated switch. The reference nodes of the switches are connected together at a common node through which the a.c. current flows, and the control nodes of the switches are connected together. A gate drive arrangement for regeneratively controlling the switches comprises a driving inductor connected between the common node and the control nodes and mutually coupled to an inductor in the load circuit for sensing current in the circuit.

Abstract: Circulating current through a resonant tank circuit and inverter switches is reduced by feeding high frequency current back through a line inductor. A resonant load circuit is connected between an inverter output node and one of the terminals of the input rectifier circuit. A high frequency capacitor has one terminal connected to an AC-side terminal of the input rectifier circuit. The line inductor and the high frequency capacitor have values selected such that instantaneous high frequency capacitor current flow into that AC-side terminal has a greater magnitude than and polarity opposite to current through the line inductor into that AC-side terminal during a portion of every cycle of the high frequency voltage.

Abstract: A magnetic field controller has been developed, which allows magnetic deflection of the arc of an alternating current high intensity discharge (HID) lamp. The controller consists of a driving circuit and an electromagnet. The system delivers a fast switching magnetic field, which can follow the alternating current signal of an alternating current HID ballast. The method minimizes the electromagnet's inductance and uses fast reacting ferromagnetic materials (Ni--Zn ferrite). To achieve the required magnetic field, a current amplifier was developed to pick up the signal from the alternating current ballast and drive the electromagnet with up to two amperes. The alternating magnetically deflected HID lamp system allows the use of magnetic deflection for alternating current HID lamps. A vehicle headlamp system can achieve multiple beam functions (day light running, low beam and high beam) of a headlight system with only one alternating current lamp.

Abstract: A method and apparatus for signaling promotional operation of a gaming device using existing fluorescent illumination lamps. An illumination lamp on a gaming device is operated continuously during normal operation, then flashed to signal promotional operation. Alternatively, an illumination lamp can be dimmed during normal operation, then operated at full brightness during promotional operation. To achieve flashing and dimming operation, a conventional starter is removed from a socket in a fluorescent lamp fixture and replaced with a controllable starter that fits into the same socket. The starter has a pair of wire leads for receiving a control signal for flashing or dimming the lamp. The controllable starter includes a starter circuit having a switch connected between two power terminals of the starter. When the switch closes responsive to the control signal, it shorts circuits the lamp, thereby extinguishing the arc and allowing preheat current to flow in the heating filaments of the lamp.

Abstract: A lighting circuit for a discharge lamp comprises a DC power supply circuit having a coil and a capacitor at its input stage, a DC-AC converter for converting the output voltage of the DC power supply circuit to an AC voltage and supplying the AC voltage to a discharge lamp, ignition means for generating an ignition pulse to the discharge lamp, and control means for performing variable control on the output voltage of the DC power supply circuit 3. The control means 6 performs such a boosting operation as to boost the output voltage of the DC power supply circuit 3 to a predetermined voltage under a loadless condition while the ignition pulse generated by the ignition means 5 is supplied to the discharge lamp 11 to thereby light the discharge lamp 11. During the boosting operation, the ignition means 5 applies the ignition pulse to the discharge lamp 11, lighting the discharge lamp.

Abstract: A lighting circuit for a discharge lamp capable of improving the lighting performance of a discharge lamp with a simple circuit structure to thereby prevent a lighting failure at the end of the lifetime of the discharge lamp. The lighting circuit 1 comprises a DC power supply circuit 2, DC-AC conversion means 3 for converting a DC voltage output from the DC power supply circuit 2 to an AC voltage and supplying the AC voltage to the discharge lamp 5, a circuit element 6 (a switch element or a current limiting element) for blocking or limiting a current counter-flowing to the DC power supply circuit 2 from the DC-AC conversion means 3, and an inductive load 4 connected in series to the discharge lamp 5. A series circuit of a Zener diode 7 and a passive element 8 (a capacitor or a resistor) is provided in parallel to the circuit element 6, so that when the Zener diode 7 conducts, a rise in an auxiliary voltage for reignition is suppressed.

Abstract: An AC driving signal of a frequency in the vicinity of the resonance frequency of a piezoelectric transformer is generated by a variable oscillation circuit and the waveform of the output signal of the variable oscillation circuit is shaped so as to be substantially sinusoidal by a waveform shaping circuit and the output of the waveform shaping circuit is subjected by a driving circuit to current amplification or voltage amplification so as to be amplified to a level sufficient for driving the piezoelectric transformer and the output of the driving circuit is subjected to current limitation, and then input to the piezoelectric transformer and the output signal of the transformer is applied to a cold cathode fluorescent lamp so that the cold cathode fluorescent lamp is lit and even if the impedance of the cold cathode fluorescent lamp decreases, the piezoelectric transformer cannot supply a large current.

Abstract: A circuit arrangement and control thereof for igniting a high intensity discharge (HID) lamp, for reducing the high frequency ripple superimposed on the low frequency rectangular waveform lamp current after ignition, and for increased circuit efficiency. The high frequency ignition voltage is only applied to the lamp during ignition phase and is mainly generated by the second stage of the low pass (LP) filter. The first stage of the LP filter whose resonant frequency is below the second stage further attenuates the high frequency ripple current through the lamp in normal operation. The resulting lamp current is a low frequency rectangular wave with less than 10% high frequency ripple. Acoustic resonance is avoided. The inductor in the first stage of LP filter is operated in discontinuous current mode. Doing so, the active switches are in zero current switching (ZCS) to maximize the circuit efficiency.

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: Proposed for the purpose of starting a high-pressure discharge lamp is a cuit which in the conventional way comprises a starting transformer (12) whose secondary side is connected to the lamp to be started and whose primary side is connected to a circuit triggering the starting pulse, the circuit triggering the starting pulse generating starting pulses with a pulse duration of less than 0.5 .mu.s and a repetition frequency of at least 2 kHz. An IGBT (Insulated Gate Bipolar Transistor) (14) is preferably used as switching element.

Abstract: Electronic ballast system for fluorescent lights. A power oscillator connected to the primary winding of a power transformer for operation at a predetermined frequency in the range of 10 KHz to 5 MHz, and a ballasting network is connected to the secondary winding of the transformer and to one or more fluorescent lamps. The ballasting network is resonant at a frequency within about .+-.10 percent of the predetermined frequency, and in some embodiments, the resonant frequency of the ballasting network remains the same regardless of the number of lamps connected to it.

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: In an electronic ballast, a half-bridge inverter is powered from a DC voltage and provides an AC output voltage having a waveform with trapezoidally shaped half-cycles. The DC voltage is obtained by way of a pre-converter with a control input operative to permit control of the magnitude of the DC voltage. The AC voltage is applied across the primary winding of a leakage transformer, whose loosely coupled secondary winding is connected across a gas discharge lamp. The internal inductive reactance of the secondary winding constitutes a lamp ballasting means by way of limiting the magnitude of the resulting lamp current to a desired level. Prior to the flow of lamp current, the magnitude of the DC voltage is controlled by negative feedback to the control input so as to remain at a maximum level. After lamp current has started to flow, by negative feedback derived from the lamp current itself, the magnitude of the DC voltage is reduced so as to bring the magnitude of the lamp current down to the desired level.

Abstract: The present invention relates to a device for starting and supplying a fluorescent tube, including a resonant system connected to the tube and to a rectified supply circuit with a switch in series. A first detector controls the switch to turn off when the current provided by the supply exceeds a determined threshold; and a second detector controls the switch to turn on for each transition through zero of the voltage on a node of the resonant system and for each transition through a minimum of this voltage.

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: 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: Disclosed is an integrated circuit for use in a ballast circuit for supplying a.c. current to a resonant load circuit incorporating a gas discharge lamp and a resonant inductance and capacitance. The integrated circuit comprises a d.c.-to-a.c. converter circuit comprising first and second switches serially connected between a bus pin, for connection to a bus conductor at a d.c. voltage, and a reference pin, for connection to a reference conductor. The switches are connected together at a node connected to a common pin through which the a.c. current flows, have respective control nodes connected to a control pin, and have respective reference nodes. The voltage between the control pin and an associated reference node determines the conduction state of the associated switch. A first embodiment also includes first and second resistors serially connected between the bus and reference pins, with their intermediate node connected to an intermediate pin.

Abstract: A ballast circuit for a fluorescent lamp for starting the fluorescent lamp and a compact fluorescent lamp is provided. The ballast circuit adopts a bypass capacitor which bypasses a high frequency and high harmonics to a smoothing portion for compensating a recovery characteristic of a rectification diode which causes a problem by feeding back high frequency currents (most of them are I.sub.L) which flow during the ignition of a lamp to a power source input, and including a high frequency component much included in a rectifying and smoothing operation. Thus, a power factor increases 95% or more.

Abstract: A sequential feedback control system for an electronic ballast provides feedback control during soft start and dimming operations. The system includes a feedback control portion that generates a feedback signal responsive to the power consumption of the ballast and receives a control signal for controlling the power consumption of the ballast. A dimming controller generates a dimming signal responsive to a time signal, and a soft start controller generates a soft start signal responsive to the time signal. An adder generates the control signal by adding the feedback signal and the dimming signal. The dimming controller includes a first resistor for setting the steady state power level during dimming operations and a second resistor for setting the rate of change of the power level.