Abstract: A discharge lamp lighting device employs first and second series circuits, each series circuit including two switching elements and a connecting point located therebetween. The first and second series circuits are both connected in parallel across a DC voltage source. A load circuit, including a discharge lamp, is connected between the two connecting points in the first and second series circuits. ON/OFF timing of the switching elements in the first series circuit varies between in-phase and 180 degrees out-of-phase from ON/OFF timing of the switching elements in the second series circuit. The ON period ratio of the switching elements is different in at least one of the first and second series circuits. The device allows dimming of the discharge lamp over a wide range, and lighting of the discharge lamp with a small supplied power.

Abstract: A low cost multipurpose electronic ballast for ultraviolet transilluminators and crosslinkers for starting and operating four or more ultraviolet lamps simultaneously. The electronic ballast is designed to be capable of operating with input voltages ranging from 85 volts AC to 250 volts AC and input frequencies ranging from 40 Hertz to 400 Hertz. The output to the lamps comes from a group of capacitors which control the current to the lamps. Because the output comes from capacitive ballasts in parallel, alternate sets of capacitors can be switched to alternate sets of lamps allowing the central ballast control to be used with different sets of lamps. By placing another set of capacitors in parallel with the existing output capacitors and making a momentary connection, a momentary power boost can be achieved. This feature also allows a variable intensity control comprised of a number of different size capacitors in series with the parallel group to vary the total current to all the lamps.

Abstract: A circuit with a transistor common to both the inverter and the boost converter powers a gas discharge lamp. In a half-bridge inverter, a boost inductor is coupled between the rectifier and the junction between two switching circuits.

Abstract: An electronic ballast draws current from the power line with power factor over 90% and total harmonic distortion under 20%, and powers two series-connected 48"/T-12 fluorescent lamps with a 30 kHz current having crest-factor better than 1.7. The ballast includes a power-factor-correcting up-converter and a half-bridge inverter providing a 30 kHz squarewave voltage across a series-resonant high-Q L-C circuit. When the L-C circuit is not loaded, the magnitude of the 30 kHz voltage developing across its tank capacitor is clamped by non-dissipative means to a peak-to-peak magnitude equal to the magnitude of the inverter's DC supply voltage. The ballast output voltage consists of the sum of two components: (i) the 30 kHz voltage across the tank capacitor, and (ii) a 30 kHz voltage obtained from an auxiliary winding on the tank inductor. The ballast output voltage is non-pulsing and is provided at a pair of ballast output terminals across which are series-connected the two 48"/T-12 fluorescent lamps.

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: In an electronic ballast, a half-bridge inverter is powered from a constant DC voltage and provides an AC output voltage having a waveform with trapezoidally shaped half-cycles. This 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 pre-established desired level. The ballast is enclosed in a steel housing of conventional shape and size (i.e., rectangular: about 2.3" wide, 1.5" high, and 8.2" long). Significant power losses may result from magnetic coupling to the walls of the steel housing of the substantial leakage flux surrounding the leakage transformer.

Abstract: A novel high frequency LCLC double resonant electronic ballast has been developed for gas discharge lamp applications. The ballast consists of a half-bridge inverter which switches at zero voltage crossing and an LCLC resonant circuit which converts a low ac voltage to a high ac voltage. The LCLC resonant circuit has two LC stages. The first LC stage produces a high voltage before the lamp is ignited. The second LC stage limits lamp current with the circuit inductance after the lamp is ignited. In another embodiment a filament power supply is provided for soft start up and for dimming the lamp. The filament power supply is a secondary of the second resonant inductor.

Abstract: The present invention provides an apparatus for operating an electronic lamp from an AC line (10) and has a rectifier circuit (12), a power coupling circuit (18), a starting circuit (22), a resonant circuit (24), a feedback circuit (26), a driving circuit (28), and an output coupling circuit (30). The rectifier circuit (12) is connected to the AC line (10) and has a positive output terminal (14) and a negative output terminal (16) for providing DC operating power. The power coupling circuit (18) is connected to the DC operating power and provides power to a drive node (20. The starting circuit (22) provides a starting pulse which starts the feedback circuit (26) and the driving circuit (28) into oscillation. The resonant circuit (24) is connected to the drive node (20) and has a resonant node (32) for providing output power to the electronic lamp (40).

Abstract: A power supply is plugged into an ordinary household electrical outlet and conditionally provides a high frequency current at a power receptacle operative to receive the power plug of an ordinary table lamp; which table lamp has a special fluorescent lamp screwed into its lamp socket. Provided the special fluorescent lamp is indeed screwed into the lamp socket, and provided the lamp'switch is in its ON position, the power supply does in fact supply high frequency current from its power receptacle; which high frequency current powers the special fluorescent lamp at a nominal power level, thereby to provide for high-efficacy luminous output. A storage battery contained within the power supply is kept fully charged by current derived from the power line voltage normally present at the electrical outlet and functions such as to cause high frequency current to be supplied from the output receptacle even if the power line voltage were to be disrupted.

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 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: 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 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: The invention provides a light controller for lamps which can reduce the number of parts, cost and size. A rectangular wave voltage output from an astable multivibrator (1) is inverted by an inverter (3) and then supplied to a gate of a P-channel MOS FET (5) for on/off driving the MOS FET (5). A current is thereby caused to flow through a lamp (7) for lighting it up. By changing a resistance value of a variable resistor (2), a cycle of the rectangular wave voltage is changed and, therefore, an amount of the current flowing through the lamp (7) is changed so as to vary the illumination intensity of the lamp.

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 gas discharge lamp ballast provides near unity power factor simultaneously with high-frequency lamp ballasting in a single switching power conversion stage resulting in efficiency improvements, reduction in size and weight and reduced component count and cost. The single conversion stage comprises a fast-recovery diode connecting in series the input inductor, energy transfer capacitor and the resonant matching network, and switching means alternately connecting the first junction between the input inductor and energy transfer capacitor, or the second junction between the matching network and the other side of said capacitor to the return current path. The switching means comprises two current bidirectional switches driven out of phase, thus producing a square-wave high frequency voltage source, which is in turn converted by the resonant matching network into a sine-wave ac current source required by the gas discharge lamp.

Abstract: A circuit for igniting and operating a discharge lamp includes a DC-AC converter provided with a first branch coupled to a DC voltage source and including at least one switching element for generating an alternating current at a frequency f. A load branch is coupled to the first branch A and includes inductive means (L), capacitive means, and an inductor for coupling the lamp to the load branch. A control circuit switches the switching element at the frequency f and includes a resonant circuit of a further inductor and a further capacitor. An ignition voltage limiter includes a second branch coupled to the resonant circuit and comprising a series arrangement of a frequency-dependent impedance and a semiconductor element of varible impedance as a function of its control electrodes potential at its control. A third branch is coupled to the load branch and to the control electrode of the semiconductor element for influencing the potential of the control electrode dependent upon the lamp voltage.

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: 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: 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: 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: A circuit arrangement provided with a switch mode power supply energized with a pulsatory input current generated by means of high-frequency switching of the main switching means HS (3) provided in turn with a drive circuit (6) having at least drive switching means SS (60) and connected to a return current line (7).A self-inductance element (61) is included in the drive circuit, preferably between the main switching means HS and the drive switching means SS. This arrangement results in a rapid level shifter of compact construction.

Abstract: A power supply for a VF display generates a DC filament voltage from a battery by either a switched transformer supply or a monolithic regulator circuit. Where a higher-than-battery voltage is needed for anode and grid voltages, another monolithic regulator circuit or the switched transformer is used. An H-switch develops an alternating voltage from the DC voltage and applies it to the display filament. A controller for the H-switch is a logic circuit including flip-flops which toggle in response to a low frequency pulsed dimmer signal to synchronize the filament half cycles with the dimmer phases. Slew rate control ramps the H-switch control signal to produce a trapezoidal waveform in the filament current having reduced radio frequency emissions.

Abstract: In an electronic ballast, an L-C series-resonant circuit is connected across the output of a full-bridge inverter while two Rapid-Start fluorescent lamps are series-connected across the tank capacitor of the L-C circuit. The full-bridge inverter is driven in such manner that the inverter's output voltage consists of a series of rectangular voltage pulses of alternating polarity and controllable width and frequency. When the lamps are fully powered, the inverter's output voltage consists of alternating pulses of frequency about equal to the natural resonance frequency of the L-C circuit and with each individual pulse-width about equal to half of the fundamental period of the natural resonance frequency of the L-C circuit.

Abstract: A unipolar ignition of the invention provides a current waveform at the ignitor plug which initially rises relatively slowly, followed by a transition to a fast rising current which quickly peaks and thereafter slowly dissipates. Such a current waveform provides an initially hotter and longer lasting spark which does not harm the ignitor plug of the system or shorten its life expectancy. Neither does the spark create stress on the solid state circuitry which delivers the energy to the ignitor plug. To provide the foregoing spark and current characteristics, an inductor having a saturable core is in series with the ignitor plug, and it provides an initially high inductance which limits the rate of current rise at the plug as energy is transferred from an energy storage device to the plug. As the current through the inductor increases, its core begins to saturate and the effective inductance begins to decrease, allowing the current to rise more quickly.

Abstract: A device for operating a gas discharge lamp is disclosed which includes a voltage transformer preferably an inverse transformer, to whose output a bridge circuit is connected, with the lamp being disposed in the diagonal of the bridge. A component disposed in the vicinity of lamp and able to carry an electrical potential is arranged in such a manner that an electrical field is able to develop between the lamp and the component. The component is connected with that terminal at the output of the voltage transformer at which the potential is positive relative to that at the other terminal.

Abstract: A stabilizer circuit includes a double stabilization device having two active terminals exchangeable with each other when a power switch is turned off and turned on one time, a relay has a coil connected to one of the terminals of the double stabilization device, two capacitors or inductors are connected to the lamp and coupled to the coil of the relay, and have different capacitances or inductances, such that the output energy and the lightness of the lamp can be adjusted.

Abstract: A protection circuit for electronic ballasts which use charge pump power factor correction includes a switch with an overvoltage sensor, a resistor and a diode. In the event of a fault condition, the switch disables the charge pump power factor correction, while the resistor and diode prevent the switch dissipating unduly large amounts of energy.

Abstract: The Lamp (La) is connected in series with first reactive impedances (C1, . To generate pulses, one or more second reactive impedances (C3, L3; C3-L2) are located as energy storage elements in series with one or more switch elements (S3, VTh1, VD1) to at least one of the first reactive impedances (C1, L1) and also in series with the high-pressure gas discharge lamp.

Abstract: A gas discharge lamp ballast with an indicator of operability of the ballast is disclosed. The ballast circuit comprises circuitry for providing a d.c. bus voltage on a bus conductor with respect to a ground, and a resonant load circuit. The resonant load circuit includes lamp terminals for connecting to a removable gas discharge lamp, a resonant inductor, and a resonant capacitor. The resonant inductor and resonant capacitor are selected to set a magnitude, and resonant frequency, of a bidirectional current in the lamp. Further included is a converter circuitry, including first and second serially connected switches coupled between the bus conductor and the ground, and providing to the resonant load circuit, at a node coupled between the first and second switches, a voltage that alternates between first and second voltage levels.

Abstract: An electronic ballast circuit for multiple fluorescent lamps. Control is achieved by varying the voltage and the frequency of operation of an inverter utilized to drive the fluorescent lamps. A separate voltage boost converter provides regulated voltage to the converter. Dimming is accomplished by varying the voltage either manually or in response to sensor circuitry.

Abstract: A ballast for a gas discharge lamp circuit has a d-c output which contains three series-connected diodes connected across the output terminals, a pair of capacitors connected from different respective nodes of the diodes to respective ones of the output terminals, and a resistor connected between two of the diodes. The resistor increases the circuit power factor to greater than 0.95.

Abstract: A circuit is disclosed to implement an energy saving electronic ballast (1A) for driving a fluorescent lamp or tube (2). The circuit is characterized by a high power factor, low harmonic distortion and minimized radio frequency interference. The circuit includes a unique DC power supply (4) comprising a high pass filter (8), which receives an AC input signal, a diode bridge rectifier (6) and a high speed diode rectifier (D2) which cooperates with the bridge rectifier to provide the power supply with first and second rectification stages. A current regulating capacitor (C4) for driving the fluorescent lamp or tube is connected to the DC power supply between the first and second rectification stages. A trigger and high frequency oscillator are provided after the second rectification stage of the power supply to provide the DC current necessary to operate the ballast circuit.

Abstract: A power-line-operated frequency-converting power supply provides a 30 kHz current-limited AC voltage at an output receptacle. A neon lamp is connected across the secondary winding of a gapped ferrite-type leakage transformer, the primary winding of which is connected with the output receptacle by way of a light-weight cord, thereby permitting the lamp-transformer combination to be located remotely from the power supply. The secondary winding is arranged to have a well defined inductance; which inductance is tuned to resonate at 30 Khz by way of a parallel-connected tuning capacitor. Tightly coupled with the secondary winding is a control winding with which is connected a protection circuit operative to place an auxiliary capacitor across the control winding in case the neon lamp fails to ignite within a few milli-seconds, thereby detuning the secondary winding enough to protect the power supply and the leakage transformer from sustained overload.

Abstract: A fluorescent lamp ballast having improved power factor by providing high frequency signals fed back to the a.c. side of the ballast rectifier. The feedback signal is regulated by limiting or reducing the voltage gain of the feedback signal based on the level of the unregulated feedback signal or rectified signal, respectively.

Abstract: A power source device includes a voltage converting means to input side of which a DC voltage source is connected and to output side of which a capacitance element and a load circuit are connected, while a control circuit is connected to the voltage converting means and the load circuit, the latter circuit having a load impedance made lower upon starting of a load in the load circuit than that in stable lighting of the load, wherein such control constant as oscillation frequency and duty are made to be substantially constant at the time of the starting and stable lighting of the load, and a switching means in the voltage converting means is turned OFF when the capacitance element has a voltage below a predetermined value.

Abstract: An information processing apparatus employs a liquid crystal display and a fluorescent lamp for backlighting the screen of the liquid crystal display. A lighting circuit for supplying alternating current lighting power to the fluorescent lamp receives input power from either a commercial alternating current power source or from a direct current battery. The level of the lighting power supplied to the fluorescent lamp is determined based upon a determination of whether the input power is being supplied from the commercial power source or from the battery.

Abstract: A power supply circuit for a gas discharge lamp is disclosed. The power supply circuit includes a circuit for providing a d.c. bus voltage on a bus conductor, and a resonant lamp circuit. The resonant lamp circuit includes a gas discharge lamp, a first resonant impedance in series with the gas discharge lamp, and a second resonant impedance substantially in parallel with the gas discharge lamp. The resonant load circuit operates at a resonant frequency determined by the values of the first and second resonant impedances. Further included is a series half-bridge converter for impressing across the resonant load circuit a bidirectional voltage, and thereby inducing a bidirectional current in the resonant load circuit.

Abstract: A ballast stabilization arrangement is provided for minimizing or eliminating lamp current oscillation, or moding, of gas discharge lamps, such as fluorescent lamps, and a method for carrying out this arrangement is described. This is carried out by adding a frequency response zero to the current circuitry in a ballast. An example of this circuitry includes a feedback network where a sensed lamp current signal is compared with a reference signal by an error amplifier having a resistance placed in series with its feedback capacitance to implement the zero in the frequency response of the control circuit.

Abstract: A versatile electrical circuit for controlling the operation of a variety of high intensity discharge, high and low pressure sodium, mercury vapor, metal halide, or xenon arc lamps uses a pulse-width-modulator to regulate the alternating or direct current drawn through the lamp from a regulated power source in accordance with the lamp power rating and the desired light intensity setting and in response to the current sensed through the lamp, and may be powered by an AC or DC power source. The circuit uses a H-bridge to apply an alternating voltage to the lamp that does not include any transformer.

Abstract: An electronic ballast can be connected between either a DC power supply or an AC power supply and a gas discharge lamp, such as a metal halide lamp and control the electrical power supplied thereto. An inverter receives a DC power and generates a periodic waveform at a controlled frequency. A resonant circuit is connected to the inverter and tuned to resonate at a predetermined frequency and generate an output voltage. A coupling capacitor is connected between the resonant circuit and the discharge lamp and supplies the output voltage of the resonant circuit thereto. A controller sets the frequency of operation of the inverter near the resonant frequency of the resonant circuit. The controller is responsive to at least a predetermined set point control voltage and to the output voltage of the resonant circuit. The resonant circuit is tuned to increase the voltage from the inverter means to a level sufficient to cause the discharge lamp to enter a glow mode of operation.

Abstract: A circuit (100) for powering fluorescent lamps (102, 104 & 106) includes a switch (50) having "open" and "closed" positions. When power is initially applied to the circuit, the lamps are powered at full power to enable them to "strike". After a short period, the power is reduced to the lamp. A control circuit (300) thereafter senses if the switch has been "toggled". If toggled, the power to the lamps is increased, and the lamps brighten. The circuit uses a conventional two-position switch and conventional wiring and avoids the need for additional switches and additional wiring.

Abstract: A resonant inverter has transistor switches (20, 30) arranged to conduct current from a d.c. source (10) alternately in one direction and the other through an inductor (40) and capacitor (42). The transistor switches (20, 30) are turned on alternately by signals from secondary windings (24, 34) of a drive transformer (44) having a primary winding (45) in series with the inductor (40) and capacitor (42). To control the output power of the inverter, a control circuit (50) senses reversal of current in through the inductor (40) and capacitor (42) and turns off one of the transistor switches (30 ) a predetermined time after current reversal. Current reversal is sensed by an additional transformer (60) having a primary winding (61) in series with the inductor (40) and capacitor (42). The control circuit (50) includes a timer (52) controlling the predetermined time, which may be varied to vary the power output of the inverter. A load (80) is connected across the inductor (40 ) or capacitor (42 ) .

Abstract: A power supply is integrally combined with a power plug, and the combination is adapted to be plugged into an ordinary household electrical outlet and operable to provide a power-line-isolated output of 120 Volt RMS at a frequency of about 30 kHz. The Volt-Ampere product available from this power supply is limited to be no more than 100 Volt-Ampere. Due to the high frequency, the electric shock hazard associated with this 120 Volt/30 kHz power supply is not higher than it is for a power supply having a voltage of only 30 Volt RMS at 60 Hz. The power supply, which also has receptacle means operable to receive and hold an ordinary electric power plug, is interposed between an ordinary household electrical outlet and the power plug of an ordinary table lamp.

Abstract: An electronic ballast for starting gas discharge lamps provides lamp power regulation within a predetermined range, but allows power regulation to drop out in response to load shedding conditions.

Abstract: A miniature electronic ballast with low radio frequency interference (RFI) for operating a discharge lamp by amplitude modulation and two frequency operation. A high frequency operating voltage (approximately 1-2 MHz) is generated and is amplitude modulated at a relatively lower frequency (approximately 20-50 KHz). This operating voltage is demodulated to suppress the high frequency carrier voltage (1-2 MHz) and the low frequency modulating signal (20-50 KHz) itself is applied to the discharge lamp to energize same. The use of the high frequency operating voltage makes it possible to reduce the size of the magnetic components in the electronic ballast, whereas the low frequency voltage actually applied to the discharge lamp avoids problems of RFI that otherwise would occur if the high frequency carrier voltage itself was applied to the discharge lamp.

Abstract: A circuit arrangement for operating a low-pressure mercury discharge lamp by a high-frequency current which includes a DC component and a high-frequency AC component. The circuit arrangement has a switching device for generating the high-frequency AC component from a supply voltage, an asymmetry device for rendering a first amplitude of the high-frequency AC component in a first polarization direction and a second amplitude of the high-frequency AC component in a second polarization direction unequal to one another, and a DC device for generating the DC component. The polarity of the DC component coincides with the polarization direction of the greater of the two amplitudes. Thus, striations in a low-pressure mercury discharge lamp operated on the circuit arrangement can be rendered invisible over a wide range of powers consumed by the lamp.

Abstract: A driving scheme for a high intensity discharge lamp. The driving scheme eliminates the need for a level shifter by requiring only one reference level in determining the level of current to be produced by the down converter. The down converter has a substantially constant D.C. voltage input and consumes a relatively low amount of fixed power relative to the load attached across the output of the down converter.

Abstract: The present invention is directed to a control circuit for providing a substantially constant current to a high-pressure sodium lamp. The control circuit preferably comprises a circuit for providing a rectified voltage signal, and a ballast having first and second contacts to operatively connect the lamp therebetween. The ballast generates and controls a peak current through the lamp based on the value of a controlled voltage. The control circuit further comprises a current sensor to sense the amount of current through the lamp, and a buck-boost voltage control circuit to control the value of the controlled voltage in order to provide a substantially constant peak current through the lamp based on the amount of current sensed by the current sensor. By controlling the amount of voltage seen by the lamp, the buck-boost voltage control circuit controls the amount of current through the lamp, thereby providing constant color temperature regardless of the fluctuations in lamp impedance.

Abstract: A high frequency power supply for neon and mercury luminous tubes including means for simultaneously suppressing bubbles formed in neon tubes and for minimizing migration of mercury commonly associated with the use of solid-state luminous tube power supplies.