Abstract: In a high-frequency electronic ballast, a screw-in fluorescent lamp is connected with and powered by way of a series-resonant LC circuit. A resistive load is connected with the LC circuit, thereby to constitute a load therefor before ignition of the fluorescent lamp or in case the fluorescent lamp were to fail to ignite.

Abstract: An electronic fluorescent lamp ballast having output voltage stabilized by a bandpass filter connected between a transformer control winding and the switching electrode of the switching transistor. In one embodiment especially adapted for ballasts which power multiple lamps, the filter causes oscillation frequency to vary with the number of lamps lit in such a way that output (lamp) voltage remains relatively constant. A filter for this application preferably includes a low-Q tank circuit in the series path of a &pgr; section, and has an input high pass T section. In another embodiment, a low cost electronic ballast having power feedback uses passive bandpass filters between transformer control windings and the control electrodes, so as to simplify the control and driver circuitry.

Abstract: A circuit arrangement for operating at least one high-pressure discharge lamp with a high-frequency alternating voltage, the circuit arrangement having a voltage converter (W) with an alternating voltage output (j10, j11), a load circuit which is connected to the alternating voltage output (j10, j11) and which has at least one lamp inductor (L1), a coupling capacitor (C1) and terminals (j12, j13) for at least one high-pressure discharge lamp (LP), and a starter (Z) with a high-voltage source and a high-voltage DC output (j14, j15) for starting a gas discharge in the at least one high-pressure discharge lamp (LP). The coupling capacitor (C1) is connected to the high-voltage DC output (j14, j15) via a charging resistor (R1).

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: A power supply for a xenon arc lamp that will automatically shut down if the lamp current is too high, the lamp voltage is too high, or the lamp requires too many trigger pulses to ignite it. Such conditions indicate faults in the lamp itself and should not be operated this way for safety. Lamp-on and end-of-lamp-life indications are provided to the operator for maintenance. The cooling fan power supply must be normal or the lamp will be shut off or not started. In combination, such provide a lamp system that can safely operate at very high powers.

Abstract: The electrodes of a discharge lamp are prevented from reaching damaging temperatures which tend to occur when the discharge lamp is near the end of its useful life. The combination of a discharge lamp and luminaire contribute to ensuring the discharge lamp remains unilluminated when nearing the end of its useful life to prevent high temperature damage. Load circuit characteristics are set to provide low release voltage and high short-circuit current during full-intensity illumination, and high release voltage and low short-circuit current during dimmed operation. The discharge lamp operating in a dimmed mode at the end of its useful life is switched to full-intensity illumination mode to ensure the discharge lamp becomes unilluminated. This configuration prevents high temperatures at the electrodes from damaging the glass bulb, base, socket and other components of the discharge lamp and luminaire.

Abstract: An electronic ballast for reducing blackening of a high intensity discharge lamp, reducing stress on both the lamp and ballast components caused by excessive voltage and current flow and increasing the lamp's effective life. These advantages are achieved through a ballast controller which readjusts the operating frequency of the lamp during each of the three phases of lamp start-up to limit lamp voltage to a predetermined level.

Abstract: A circuit arrangement for igniting and operating an electrodeless discharge lamp provided with a half-bridge commutator having two switching elements each having an emitter electrode and a control electrode and a parasitic capacitance in between. Each switching element is alternately switched to a conducting state by means of a resonant control circuit. The resonant control circuit is coupled to an oscillator by way of a transformer. The resonant circuit is provided with a capacitor which forms a part of the oscillator.

Abstract: A model and computer program for designing the output stage of a high frequency electronic ballast for a fluorescent lamp. The user specifies a plurality of parameters relating to the operation of the fluorescent lamp, including lamp running power, running voltage, maximum preheating voltage for the lamp, minimum running frequency for the lamp, and an input voltage for the ballast. Based upon these parameters, the computer program calculates the values for various components of the ballast, including the inductor and capacitor of the output stage, such that the preheat frequency is greater than the ignition frequency, the ignition frequency is greater than or equal to the running frequency, the preheat voltage is less than the maximum preheat voltage, and the difference between the preheat frequency and the ignition frequency is greater than about 5 kHz.

Abstract: A fluorescent lighting system has: (A) a central power supply including: (i) a parallel-resonant self-oscillating bridge inverter operative to provide a 35 kHz sinusoidal output voltage at a pair of primary output terminals; (ii) a tank-inductor and a tank-capacitor parallel-connected across the primary output terminals; and (iii) plural pairs of secondary output terminals, each connected with the primary output terminals via its own dedicated current-limiting sub-circuit; thereby to prevent a load connected therewith from drawing more than a certain amount of power; thereby, in turn, to render each pair of secondary output terminals fire-hazard-safe and shock-hazard-safe; each pair of secondary power output terminals being connected with its own power output receptacle; and (B) a light-weight power cord plug-in-connected with one of the power output receptacles and having a pair of power conductors between which are connected a number of individually ballasted lighting units; each lighting unit having at lea

Abstract: To control low-pressure fluorescent lamps, there is provided a device comprising a first change-over switch circuit and a second change-over switch circuit, respectively including a first power transistor and a second power transistor. The first change-over switch circuit first of all measures the period of time when the second power transistor is on. Then, secondly, it turns the first power transistor on for a period equal to the period measured.

Abstract: A ballast includes a resonant inverter circuit which limits the voltage applied to a lamp when it fails to light. In one embodiment, the inverter includes first and second switching element having conduction states controlled by respective first and second control circuits. The second control circuit includes a third switching element which controls the conduction state of the second switching element. An end of life circuit includes a first threshold circuit coupled to the third switching element for disabling the inverter when the voltage applied to the lamp becomes greater than a first predetermined threshold. In another embodiment, the second control circuit includes a fourth switching element for controlling a duty cycle of the third switching element and the end of life circuit includes a second threshold circuit. When the lamp voltage becomes greater than a second predetermined threshold, the fourth switching element reduces the duty cycle of the third switching element.

Abstract: AC voltage is applied to a resonant unit provided with an inductor and a capacitor AC current is supplied to a discharge tube connected to one of the inductor and the capacitor according to the switching operation of the two power semiconductor elements connected in a bridge manner. The resonant unit and first and second voltage drop units are connected in series between I/O terminals of the bridge and the voltages of the first and the second voltage drop units are applied as signals of opposite phases to control terminals of the two power semiconductor elements.

Abstract: The invention relates to a lamp arrangement having a resonant circuit arrangement that is balanced and has two LC series circuits each connected between a respective inverter output terminal and a lamp terminal. The two inductive elements being coupled together via a single core.

Abstract: A high-frequency filtered dimmable electronic ballast circuit for powering low-pressure fluorescent lamps includes an input protection device; a radio-frequency filter connected to an output of the input protection device; a rectifier connected to an output of the radio-frequency filter; a power factor correcting switching power supply device connected to an output of the rectifier; a current controlled push-pull converter connected to an output of the switching power supply device; a series-parallel resonant filter composed of a capacitor in series with two inductors having a common connection in parallel with an additional capacitor connected to an output of the push-pull converter to maintain voltage wave forms essentially sinusoidal and of constant amplitude regardless of loading; a fluorescent lamp connected to an output of the resonant filter; and an external on/off switching circuit connected directly or by an optical or magnetic insulation device to an input of the push-pull converter for renotely tur

Abstract: A discharge lamp lighting device includes an inverter circuit connected through a first impedance element across output ends of a rectifier rectifying an AC source power, a smoothing capacitor inserted through a discharging diode in a power supply path to the inverter circuit, and a series circuit of a second impedance element, discharge lamp and inductor and connected between an output end of the inverter circuit and one output end of the rectifier, wherein a path for charging the smoothing capacitor is formed through a switching element included in the inverter circuit, and the discharging diode.

Abstract: A ballast circuit 10 for a gas discharge lamp 14, incorporates a shutdown circuit 12 for limiting voltage output of a d.c.-to-a.c. converter 21. The shutdown circuit includes a pair of terminals 66 and 68 connecting across an inductor 48 in order to sense the inductive voltage of the d.c.-to-a.c. converter 21. A rectifier network 70-76 receives the inductor voltage and generates a full-wave rectified voltage. A latch 84 is arranged to receive the rectified voltage and to enter an active state when the rectified voltage is above a pre-determined value. A time delay circuit 118 located between the rectifier network 70-76 and the latch 84 provides an adjustable delay time prior to activation of the latch network. Upon activation of the latch, the inductor voltage is decreased and the ballast circuit 10 is taken out of resonance thereby lowering the voltage and current applied to the resonant circuit 28.

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: An electronic ballast having an RF resonant inverter and RF feedback from the inverter which provides power factor correction. The feedback is provided by a capacitor coupled between an RF resonant tank circuit of the resonant inverter and a low frequency point in the ballast. Such feedback integrates the power factor correction stage with the RF resonant inverter stage and eliminates a switch and its controller. Electronic ballasts operating at RF frequencies require fast switching isolation diodes. Ultra-fast silicon diodes with very short recovery times, which have been used as such isolation diodes, are sensitive to ambient temperature and deteriorate the power factor and total line current harmonic distortion of the ballast. Use of either GaAs or silicon carbide isolation diodes instead of silicon diodes provides the ballast with a high power factor and a low total harmonic distortion.

Abstract: In the circuit arrangement for the high-frequency operation of a low-power ow-pressure discharge lamp (LP) having a mains rectifier (2) and a half-bridge circuit, a diode (D1) is connected in series and in the DC non-conducting direction in the connecting line between the second electrode (E2) of the lamp (LP) and the positive or negative pole of the rectifier (2). Moreover, the tap (M2) between the diode (D1) and the second electrode (E2) is connected to the other pole of the mains rectifier (2) via a capacitor (C1), and a resistor (R9) is connected in parallel with the diode (D1). The circuit thus created acts as a passive harmonic filter which fulfills for the circuit arrangement the IEC regulations of class D with reference to line current harmonic content.

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 provides a circuit arrangement for igniting gas discharge flash tubes including a gas discharge flash tube having two-spaced-apart electrodes, a pulse forming network and a voltage generator for supplying ignition pulses and tube burning pulses during simmer mode, the arrangement having a resonant circuit connected in circuit between the electrodes and the voltage generator, wherein the voltage generator provides the resonant circuit with AC high frequency voltage for producing gradually increasing amplitudes of an AC voltage until ignition voltage is achieved and for supplying AC voltage of a lower level in comparison to the level of the ignition voltage, for sustaining the burning of the tube during the simmer mode.

Abstract: A circuit for energizing a load includes an inverter which provides a feedback signal to a rectifier for substantially linear operation of the rectifying diodes. In one embodiment, a ballast includes a rectifier and a resonant inverter which energizes a lamp. The inverter generates a current that is split between a first path which includes the lamp and a second path which includes a feedback capacitor. A feedback path, which includes a feedback inductor, extends from the feedback capacitor to a point between the rectifying diodes. The feedback capacitor and feedback inductor resonate in series to provide a reactive feedback signal for achieving substantially linear operation of the diodes. In another embodiment, the lamp current flows to a clamp circuit for limiting the lamp current to a predetermined level.

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 dimmer ballast or output drive circuit and a drive method for a high intensity discharge lamp utilizes an overwound loosely coupled transformer having a turns ratio of preferably about one to one with a peaking capacitor across the secondary output terminals of the transformer and in parallel with the HID lamp arc electrodes. A control circuit provides a variable frequency drive voltage to the primary of the transformer. The frequency of the output voltage is adjustably controlled above the peak load power frequency. The load power and hence the light output of the lamp varies according to the frequency of the output voltage permitting a user to adjustably dim the high intensity discharge lamp.

Abstract: A pump supporting inductor (L1) is added to a half-bridge oscillator circ for a low-pressure discharge lamp (E) having a capacitive pump path, which inductor improves the pumping action of the pump path and its frequency response. Furthermore, an additional capacitor (C1) is connected between the pump path and the power supply path connected thereto, which capacitor acts as a trapezoidal capacitor in conjunction with the pump path and further improves the frequency response of the pump path.

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 technology for eliminating acoustic resonance in a fluorescent lamp is disclosed in the present invention. The feature of the invention is to provide a harmonic compensating device to work with the fluorescent lamp and its relative peripheral circuits, such that current-dependent sources are provided to modulate the current in the lamp, thereby spreading the harmonic energy of the current in the lamp and eliminating acoustic resonance.

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: 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 circuit arrangement for supplying a discharge lamp with a direct current includes input terminals for connection to a supply voltage source. A circuit portion (I) is coupled to the input terminals for generating a DC voltage from the supply voltage and is provided with output terminals between which the DC voltage is present during operation. A first branch comprising a first capacitor interconnects the output terminals and a second branch comprising a series arrangement of a second capacitor and an impedance shunts the first branch. A load branch shunts the series arrangement and comprises terminals for connecting a discharge lamp. The second branch also includes a diode so that a discharge lamp operated by way of the circuit arrangement stabilizes satisfactorily after ignition by a current supplied by the second capacitor to the lamp via the impedance.

Abstract: A ballast for a discharge lamp comprises a smoothing capacitor, an inverter circuit including at least one switching device connected in parallel to the smoothing capacitor, a driving circuit for driving the inverter circuit, an activating circuit for activating the driving circuit, a resonance circuit including first and second capacitors and an inductor connected to output terminals of the inverter circuit, a discharge lamp connected to output terminals of the resonance circuit, a third capacitor connected in parallel to the discharge lamp. A fourth capacitor and first and second rectifying elements connected in series are connected in parallel to the smoothing capacitor. Between both terminals of the fourth capacitor and terminals for connection to an AC power source, a filter and a rectifier are inserted. A terminal of the first capacitor other than that connected to the inverter circuit is connected to a junction of the first and second rectifying elements.

Abstract: A snubbing network is provided for reducing electromagnetic ("EM") radiation from and power dissipation of a lamp discharge ballast. The snubbing network employs at least one active device. That device being a switch coupled in parallel with the modulating switch within a converter of the ballast. The snubbing switch, in conjunction with a current limiting inductor, and a voltage change rate limiting capacitor serve to substantially eliminate reverse recovery current within a freewheeling diode of the converter prior to closing the larger (modulating) switch. Reducing the reverse recovery current before closing the modulating switch helps minimize power dissipation during switch closure. A benefit of reduced power dissipation is a reduction in EM radiation from the lamp ballast to noise sensitive electronic components placed nearby.

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: In a multiresonant DC--DC converter provided with a switching element (S1), a transformer (T) and a rectifier coupled to the secondary winding (S) of the transformer, the rectifier is constructed as a diode bridge (D1, D2, D3, D4). It is achieved thereby that the maximum amplitude of the voltage across the switching element is comparatively low. The switching element is highly suitable for supplying a network of LEDs.

Abstract: An electronic ballast circuit includes an input section which rectifies, power factor corrects and filters an AC input voltage to provide a rectified signal. The electronic ballast circuit also includes an inverter section which receives the rectified voltage and switches the rectified voltage to provide an AC signal to a resonant load circuit. The input section includes a resonant tank circuit which provides a high frequency current to the inverter to soft switch the switches within the inverter. In the input section, an inductor is placed on the AC side of a diode bridge rectifier advantageously allowing the removal of several prior art ballast circuit components since placing this portion of the power factor correction (PFC) circuit within the input circuit on the AC side of the diode bridge rectifier allows the bridge rectifier to perform both the rectification and current blocking functions.

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: The application of a piezoceramic resonator (PR), connected in parallel to a discharge lamp and in series to cathode filaments of a lamp, provides reliable means of preheating of cathode filaments facilitating a soft start of a fluorescent lamp. The piezoceramic resonator is a polarized piezoceramic element formed in a form of rectangular plate, disk, cylinder, etc. The linear size and shape of the PR determine the type of oscillation, electromechanical resonant frequency and frequency characteristics. The PRs with radial, contour or longitudinal oscillations are best suited for application to a piezoelectronic ballast. Piezoceramic resonators and filters as frequency-selective elements in measuring and radio communication instruments are widely used in weak alternating electrical fields, where the intensity of field does not exceed an order of volts per mm.

Abstract: A fluorescent lighting system connected to an AC voltage source providing a first AC voltage is disclosed. A converter circuit connected to the AC voltage source converts the first AC voltage to a DC voltage. An oscillator circuit receives the DC voltage and produces a second AC voltage. The oscillator circuit includes a series resonant circuit and a removable installed fluorescent lamp. The series resonant circuit includes a resonant capacitor and a resonant conductor in series. The lamp has first and second elements and is connected in parallel with the resonant capacitor of the series resonant circuit such that lighting current runs between the first and second elements. The second element is connected in series with the resonant capacitor and the resonant inductor and acts as a switching element. When the lamp is removed from the system, the absence of the switching element creates an open circuit between the resonant capacitor and the resonant inductor such that the oscillator circuit does not operate.

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: The present invention provides an improved power factor and lower harmonic distortion in the power supply circuit of a high frequency discharge lamp. An "extra" circuit path is provided so that the driving power to the lamp will "see" a load that significantly reduces the harmonic distortion and tends to cause the power factor to approach "1". In a preferred embodiment of the invention this is accomplished by providing a third capacitor with which the load circuit forms an in-series resonance circuit with the discharge lamp and its associated current-limiting inductance. The new circuit arrangement provides a high frequency current passage not provided in known lighting circuits of this type that raises the power factor and lowers harmonic distortion.

Abstract: A ballast circuit for a gas discharge lamp includes a rectifier coupled to convert current from an a.c. source to d.c. current provided on bus and reference conductors. A smoothing capacitance, coupled between the bus and reference conductors, smooths current supplied by the rectifier. A resonant load circuit includes a resonant inductance, a resonant capacitance, and means to connect to the lamp. A d.c.-to-a.c. converter circuit, coupled to the resonant load circuit, induces an a.c. current in the resonant load circuit. The converter circuit comprises first and second switches serially connected between the bus and reference conductors, and being connected together at a common node through which the a.c. load current flows. The switches each comprise a reference node and a control node, the voltage between such nodes determining the conduction state of the associated switch. The respective reference nodes of the switches are interconnected at the common node.

Abstract: A triac dimmable compact fluorescent lamp having a low power factor. A power feedback circuit coupled between the input and output stages of the lamp ballast creates sufficient current demand to sustain triac conduction at low dim levels. The power fed back from the output stage to the input stage, which includes a voltage doubler, reflects the voltage across the lamp.

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

Abstract: A novel monolithic electronic ballast controller IC for driving two MOS gated power semiconductors, such as power MOSFETs or IGBTs, connected in a totem pole or half-bridge arrangement. Advantageously, the present invention provides programmable preheat time and current, programmable end-of-life protection, lamp fault protection, over-temperature protection. The first embodiment of the invention is a closed-loop ballast controller IC intended for multiple lamp configurations, with three current-sensing inputs and programmable lamp power. Closed-loop control is accomplished through phase control, or, more specifically, a phase-locked loop (PLL) around a resonant type output stage driving a fluorescent lamp. The second embodiment of the present invention has a similar architecture to that of the first embodiment, with some modifications which allow dimming down to low light levels.

Abstract: A circuit for controlling the operating power of a fluorescent lamp by detecting the phase of the lamp resonant circuit current and regulating the phase of the current, thereby regulating the lamp power. In the preferred embodiment of the circuit, the phase of the resonant circuit current is detected using a sense resistor disposed between the low side power transistor of a half-bridge driver and ground, or between the lower voltage lamp filament and ground. The zero-crossings of the resonant circuit current is detected by comparing the voltage across the sense resistor to zero voltage. Using these zero crossings, a phase pulse is generated representing the lamp resonant circuit current as a function of time. This phase pulse is compared to a reference pulse to generate an error signal indicative of the phase difference between the phase pulse and the reference pulse.

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 electronic ballast (10) for powering at least one gas discharge lamp (30) includes a rectifier circuit (100), a line blocking rectifier (220), a bulk capacitor (240), an inverter (300), an output circuit (400), and a charging circuit (500). Charging circuit (500) is coupled between the output circuit (400) and the bulk capacitor (240) and provides operating current to the bulk capacitor (240). Charging circuit (500) also protects lamp life by preventing excessive flow of DC current in the lamp (30) following application of AC power to the ballast (10). In a preferred embodiment, charging circuit (500) includes a DC blocking capacitor (510), a lamp current blocking rectifier (530), and a charging rectifier (540).

Abstract: An improved dynamic range dimmer for gas discharge lamps is provided in which the frequency is shifted during the startup of the lamp, and the frequency is shifted and the duty cycle is varied to dim the light emitted by the lamp. When dimming is desired the frequency is shifted to increase the voltage available to the lamp, which then has its power reduced by controlling its duty cycle. Such an arrangement provides a greater range of light intensity variation. If the lamp is turned off while set to a dimmed level, then the frequency is automatically restored to the resonant value used when starting the lamp, to assure breakdown of the plasma in the lamp for proper ignition.