Abstract: A ballast includes safety circuitry which senses lamp status through various phases of ballast operation. According to one feature, the ballast is prevented from supplying an output voltage upon initial energization of the ballast when a lamp is not present at the output terminals. The presence of a filament is sensed via a DC path extending through the filament heater windings of an output transformer. When the DC path is not complete, a control input, for example the power supply input of the ballast controller, is not provided with a voltage to start ballast operation. The DC path is also used to restart the ballast if a defective lamp is replaced with a good one. Over-voltage and capacitive mode detection is also disclosed to shut down ballast output upon lamp failure/removal.

Abstract: An electronic ballast includes an inverter producing pulses having a DC component, an output circuit connecting the filaments of one or more lamps in series, and a control circuit for detecting direct current through the filaments. The control circuit includes a capacitor charged by the DC component. When the voltage on the capacitor reaches a predetermined value, the ballast applies a high voltage to the lamps. The predetermined value is not reached unless a direct current passes from the output of the inverter through all lamp filaments to the capacitor. If a lamp filament is not intact, the inverter will not apply high voltage to the lamp.

Abstract: A multi-output circuit for projection TV lamp is disclosed including a DC/DC-voltage converter, a voltage dividing portion, a driving pulse generator for generating a driving pulse, a lamp driving portion for switching the output voltage of the DC/DC-voltage converter, a voltage feeding-back portion for comparing the output voltage of the voltage dividing portion with a reference voltage, a current feeding-back portion for comparing the driving current supplied to the lamp with the reference voltage, a current detecting portion for detecting the driving current supplied to the lamp, an error amplifying portion for comparing the output voltage output from the current detecting portion, a gain controller for summing the output voltages of the voltage feeding-back portion and current feeding-back portion, and a pulse-width modulation integrated device for outputting a pulse-width modulation signal to the DC/DC-voltage converter.

Abstract: In an electronic ballast, a full-bridge inverter is powered from a DC voltage and provides a square-wave-like inverter output voltage. This inverter output voltage, which has a peak amplitude equal to the magnitude of the DC voltage, is applied to an instant-start fluorescent lamp via a current-limiting inductor connected in series with a DC blocking capacitor. 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. 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 certain maximum level. About 100 milli-seconds after initial flow of lamp current, one half of the full-bridge inverter is disabled, thereby reducing the amplitude of the inverter output voltage by half.

Abstract: To effectively suppress glow discharge of a discharge lamp, especially a h-pressure discharge lamp, immediately after starting or firing, the lamp is supplied in a second, or run-on phase with a run-up current which has a form factor F greater than one (1), for example 1.13 to 1.45, and which has an effective value I.sub.eff which is higher than the rated normal operating current of the lamp. A control circuit (C), coupled to a controllable power supply, and to a switchable bridge circuit, controls the frequency of the run-on phase current to be higher than the normal operating frequency, for example about 2 kHz with a normal operating frequency between about 90-150 Hz.

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 an output voltage thereat. The output voltage consists of sinusoidally-shaped voltage pulses of alternating polarity, with a distinct brief period of discontinuity at or near the cross-over points. A fluorescent lamp is connected by way of a current-limiting capacitor with the inverter's output.

Abstract: In accordance with the present invention, a hybrid sequence start circuit is provided for operating a plurality of instant start lamps. The circuit utilizes two coils, a primary and a secondary, and an electronic switch to start a plurality of series-connected, instant start lamps in sequence. When the circuit is energized, the electronic switch causes open circuit voltage to be applied to a first lamp by placing a low impedance across the other lamps, causing the first lamp to strike. The first lamp then conducts current, causing a starting capacitor in parallel with a second lamp to be charged, eventually, causing the second lamp to strike. The current through the second lamp shunts current away from the switch, and when this current drops below a predefined threshold level, the switch opens, effectively removing both the low impedance and the starting capacitor from the circuit.

Abstract: A method and device for controlling electric discharge lamps with electronic fluorescent lamp ballasts, using a bistable reverse switch system in the electric circuit in such manner that in turning the lamp on to a first switching condition, and after a short period of interruption of the electric circuit to the current supply of the lamp, the bistable reverse switch system acquires a second switching condition. It is thereby possible to reduce the lamp from a first level of brightness to a second lower level of brightness. It has the effect of a "dimmer" used with fluorescent lamps.

Abstract: An electronic power supply (10) includes a boost converter (100) and an inverter (600). The inverter (600) includes a first inverter node (602) having a periodically varying voltage, and a second inverter node (604) having a voltage with a peak value that is proportional to the dc output voltage of the boost converter (100). The boost converter (100) includes a control circuit (200) for driving a boost FET (110). Control circuit (200) includes a shunt circuit (300) having a shunt switch (308) for periodically turning off the boost FET (110), a drive source network (400) that is coupled to the first inverter node (602), and a load regulation network (500) that is coupled to the second inverter node (604). In a preferred embodiment, the power supply (10) includes a rectifier circuit (40) and a push-pull inverter (600), and is adapted to serve as an electronic ballast for powering at least one fluorescent lamp (702).

Abstract: To provide for automatic switch-over between a power phase and a holding se in operation of a discharge lamp (EL), a choke or ballast coil (L), serially connected to the discharge lamp, is constructed to have, with respect to current flow therethrough, a non-linear reactance value; the choke or ballast coil is wound on a core which, for example, can be a E-core in which the center leg is of reduced cross-section with respect to the outer legs; or, if one is a torroidal coil on a ring core, the ring core is preferably made of two core elements of different magnetic characteristics, connected together, for example by an adhesive, in which one core element is of low permeability material, such as iron powder or permaloy with high saturation magnetization, and a second core is formed of ferrite with low saturation magnetization.

Abstract: A ballast circuit for a gas discharge lamp 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 d.c.-to-a.c. converter circuit coupled to the resonant load circuit so as to induce an a.c. current in the resonant load circuit. The converter includes first and second switches serially connected between a bus conductor at a d.c. voltage and ground, and has a common node through which the a.c. load current flows. A feedback circuit provides a feedback signal indicating the level of current in the resonant load circuit.

Abstract: A bridge rectifier is connected with a 277Volt/60 Hz power line and provides full-wave-rectified unfiltered DC voltage to a series-combination of: i) an inductor, ii) a full bridge inverter switched in synchronism with the 60 Hz power line voltage, and iii) an electronic switching device. A fluorescent lamp is connected with the inverter's output and receives 60 Hz current of exceptionally low crest-factor, thereby operating at an exceptionally high efficacy. The electronic switching device is normally in a fully conductive state. However, it is controlled--by a photo sensor responsive to the light output of the fluorescent lamp--in such a manner that whenever the instantaneous light output exceeds a certain adjustably predetermined upper level, it switches into a non-conductive state where it remains until the instantaneous light output level diminishes to a certain adjustably predetermined lower level.

Abstract: An improved energizing circuit for starting and regulating a gaseous discharge lamp. The circuit is 100% solid state and does not require the use of any inductive components or any filaments for its proper operation. The circuit is made up of several sub-circuits including a rectifying and voltage-doubling circuit, a second multiplying circuit, a low power oscillating circuit and a high voltage amplifier circuit. A high frequency AC signal is used to ionize the gas and ignite the lamp, while a DC signal is generated by the circuit to keep the lamp illuminated once it is ignited. The size and weight of the integrated circuit ballast are such that it could be incorporated into the fluorescent lamp package itself.

Abstract: A voltage-boosting and current-regulating circuit delivers energy from a high voltage resonant circuit source to a fluorescent lamp. A controllable switch is connected in series with the lamp cathodes and is triggered into conduction during a predetermined conductive time interval within each half-cycle of current conducted through the plasma from the resonant circuit. A charging current which flows during the conductive time interval stores energy in the resonant circuit which is subsequently released as a boosted voltage and as increased current flow through the plasma. The boosted voltage allows higher efficiency illumination lamps to the used, and regulation of the conductive time interval achieves the optimal current conduction through the lamp.

Abstract: In a lighting circuit, a battery voltage is supplied via a DC booster circuit to a DC-AC converter where the voltage is converted to an AC voltage with a rectangular waveform. This AC voltage is supplied to a discharge lamp. At this time, the DC-AC converter controls the frequency of the rectangular wave output from the DC-AC converter in accordance with a signal sent to a bridge type driver from a frequency controller. A lighting detector is provided to detect if the discharge lamp has been lighted. Upon reception of a signal from the lighting detector, the frequency controller sets the frequency of the output voltage of the DC-AC converter in the pre-lighting period of the discharge lamp higher than the frequency of the output voltage of the DC-AC converter after the lighting of the discharge lamp and restricts the inversion of the polarity of the output voltage of the DC-AC converter until a predetermined time passes sfrom the point of the activation of the discharge lamp.

Abstract: A power terminal is connected to a DC power source. A differential amplifier has primary and secondary input terminals and an output terminal, and a device applies a reference voltage to the secondary input terminal of the differential amplifier. A phase inverter has an input terminal connected to the output terminal of the differential amplifier and has primary and secondary output terminals that output two output signals of opposite phase. A push-pull drive circuit has primary and secondary input terminals connected to the primary and secondary output terminals of the phase inverter, and has primary and secondary output terminals connected to a switching element that alternately turns on and off by being driven by the two output signals of opposite phase that are provided from the output terminals of the phase inverter.

Abstract: A ballast system for at least one dimmable fluorescent lamp includes a ballast inverter for driving the fluorescent lamp to provide light output and a parallel impedance for coupling across the fluorescent lamp for providing an alternative path for diverting sufficient ac current to avoid developing striated light output as the light output is dimmed. The parallel impedance may be a resistor connected in series with a diode. For multiple lamp systems, the parallel impedance may be connected across one or more of the lamps.

Abstract: A lamp starting apparatus for a liquid crystal projector is disclosed including a lamp for projecting light to a screen, a lamp starting portion for converting an impedance in starting the lamp, and increasing the energy of a starting pulse applied to the lamp, thereby starting the lamp, a lamp driving portion for driving the lamp, and an inverter for driving the lamp according to a signal output from the lamp driving portion, so that the instant lighting and re-lighting of the lamp are enabled to turn on/off the lamp at any time.

Abstract: An electronic ballast (200) includes a rectifier circuit (20), an energy storage inductor (38), a power switch (58), a control circuit (50) for driving the power switch (58), a clamp diode (46), a voltage clamping capacitor (54), a bulk capacitor (34), and an output circuit (70) for providing power to one or more fluorescent lamps (100). In a preferred embodiment, the rectifier circuit (20) includes a full-wave diode bridge (22) and a high frequency filter capacitor (24), and the output circuit (70) has a resonant inductor (72), a resonant capacitor (82), and a dc blocking capacitor (88). The ballast (200) provides power factor correction and high frequency power for fluorescent lamps, but requires only a single power switch (58) and a single energy storage inductor (38).

Abstract: A discharge lighting system includes a lighting server responsive to input power for controlling the operation of discharge lamps. An inverter in the server includes a full switching bridge having a first leg and a second leg operable at a common switching frequency but out of phase to provide for pulse width modulation and frequency variations to dim the discharge lamps. A protection circuit is provided to reduce the circulating currents resulting from an open-circuit condition. A power factor circuit includes an output capacitor which is maintained fully charged while the switching circuits are de-energized to extinguish the lamps. The charged condition of the capacitor avoids high in-rush currents when the lamps are again illuminated by activation of the switching circuit. A first tank circuit included in the inverter has a first resonant frequency which is greater than the switching frequency of the switching members.

Abstract: An improved ballast circuit for use with a compact fluorescent lamp includes an EMI filter, a rectifier and voltage amplification stage, an active resonant circuit and power factor correction stage which is connected in parallel to a lamp load. The ballast circuit includes a feedback capacitor which provides a feedback path for a portion of the high frequency current to the rectifier and voltage amplification stage. The feedback capacitor of the improved ballast circuit reduces the non-linear characteristics of the diode, thus providing almost a linear load on the input power supply and therefore achieving an improved power factor, on the order of 0.95 or greater. The improved ballast circuit may also include a dimming stage which works with the active resonant circuit to vary the amount of power that is supplied to the lamp load. The dimming stage does not require the addition of parasitic active stages and thus provides a lamp with high electrical efficiency.

Abstract: A transformerless ballast for a gaseous discharge lamp is disclosed. The ballast comprises: a rectifier; a filter for the rectifier output; a voltage divider for the filter output; an electronic gate modulating the filter output to power a lamp when the lamp is lit; a controller controlling the electronic gate responsive to variations in lamp impedance and to variations in the voltage divider output; an oscillator generating an output for predetermined period of time until after the lamp is lit; and an amplifier receiving and amplifying the oscillator output for powering the lamp when the lamp is unlit.

Abstract: A ballast includes safety circuitry which senses lamp status through various phases of ballast operation. According to one feature, the ballast is prevented from supplying an output voltage upon initial energization of the ballast when a lamp is not present at the output terminals. The presence of a filament is sensed via a DC path extending through the filament heater windings of an output transformer. When the DC path is not complete, a control input, for example the power supply input of the ballast controller, is not provided with a voltage to start ballast operation. The DC path is also used to restart the ballast if a defective lamp is replaced with a good one. Over-voltage and capacitive mode detection is also disclosed to shut down ballast output upon lamp failure/removal.

Abstract: Circuit arrangements generate start, glow, and/or run signals to be applied to and for operating a DC arc discharge lamp. A first circuit arrangement provides start, glow, and run signals. The first circuit arrangement includes a tapped transformer flyback converter circuit for combining the start and glow functions; a buck/boost converter for providing the run function; and blocking diodes for providing a blocking function for the glow circuit during the start and run modes, and further for providing a blocking function for the run circuit during the start and glow modes. A second circuit arrangement provides start and glow functions, and includes a tapped transformer flyback converter circuit for combining the start and glow functions; and a blocking diode for providing a blocking function for the glow circuit during the start mode. A third circuit arrangement includes a buck/boost converter for providing glow and run functions, and further includes an inductive storage element, such as an inductor.

Abstract: An apparatus for operating a fluorescent lamp having first and second power source circuits, the second power source circuit including a high frequency transformer having two or more outputs for supplying pre-heating electric currents to filaments, the second power source circuit being arranged to be controllable individually from the first power source circuit for supplying a tube electric current to turn on a fluorescent lamp so that the electric power level for pre-heating the filaments is switched between a state where a light adjustment is performed by turning on/off a tube electric current at high frequency and a state where the fluorescent lamp is turned off in a standby mode.

Abstract: A ballast circuit for a gas discharge lamp comprises 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. A d.c.-to-a.c. converter circuit is coupled to the resonant load circuit so as to induce an a.c. current in the resonant load circuit, and comprises first and second switches serially connected in the mentioned order between a bus conductor at a d.c. bus voltage and ground, and having a common switch node through which the a.c. current flows. A bridge capacitor has one end connected to ground. First and second feedback circuits regeneratively control the first and second switches, respectively, in response to a.c. current in the resonant load circuit.

Abstract: An arc detection and cut-out circuit is connected to an electronic ballast to detect when arcing occurs and to disable the ballast when arcing occurs. The arc detection and cut-out circuit is comprised of a current detector and a shunt circuit. The current detector detects the current in the electronic ballast to determine if arcing has occurred. If detected, the current detector causes a shunt circuit to shunt the power inverter of the ballast shutting it down. The arc detection and cut-out circuit prevents the power inverter from starting up until the power to the ballast is cycled off and back on.

Abstract: A dimmable fluorescent lamp system embodiment of the present invention comprises a fluorescent lamp with filaments at each end that are continuously heated by independent secondary windings of a transformer. A resonating capacitor is connected in series with a resonating inductor and a pair of DC blocking capacitors are connected from each end of the fluorescent lamp to put it in parallel with the resonating capacitor. A control logic drives the primary winding with a pulse-width or frequency modulated square wave that is controlled by a feedback voltage derived from a pair of rectifiers and a dropping resistor in series with one of the DC blocking capacitors.

Abstract: A dimmable fluorescent lamp system comprises a fluorescent lamp with filaments at each end that are continuously heated by a transformer. A resonating capacitor is connected in series with a resonating inductor and a pair of DC blocking capacitors are connected from each end of the fluorescent lamp to put it in parallel with the resonating capacitor. A control logic drives the resonating inductor with a pulse-width modulated square wave that is controlled by a feedback voltage derived from a pair of rectifiers and a dropping resistor in series with one of the DC blocking capacitors. An error amplifier with two gain settings, e.g., one for a range of 0-20% of maximum light dimming and the other for 20%-100% dimming, compares the feedback voltage to a setpoint. A threshold comparator establishes the switchover point between the two error gain ranges.

Abstract: A ballast circuit for driving a gas discharge having a source of pulsating and rectified AC (20), an energy storage circuit (30), a switch (40) that can have one end connected to an energy storage inductor and an opposite end that can be connected to circuit common; a control circuit (50) for opening and closing the switch (40) at a rate that is a function of at least a DC control current, a resonant circuit (60) that is coupled to the energy storage circuit (30) for energizing the gas discharge lamp.

Abstract: A hot restart circuit for a high intensity discharge lamp includes a storage capacitor and SCR connected across a tapped portion of a ballast with a breakdown device to start the SCR. A charging circuit for the storage capacitor includes a diode, a pumping capacitor and an RF choke in series from the ballast tap to the AC line, and a further diode interconnecting the capacitors. The pumping capacitor increases the charge on the storage capacitor in a stepwise fashion until breakdown voltage is reached, whereupon starting pulses are applied to the lamp. A positive temperature coefficient (PTC) resistor stops the flow of charging current to the capacitors after a predetermined interval, thereby terminating the reignition pulses and protecting the starting circuit from damage in case the lamp fails to reignite. In an alternative embodiment, a MOSFET gated by an RC timing circuit removes charge from the storage capacitor in order to terminate the reignition pulses after a predetermined interval.

Abstract: A new fluorescent device including an electronic fluorescent starter, a phase leading capacitor, a ballast, a bridge rectifier, a fluorescent lamp, a brightness compensation circuit, and a control circuit, the electronic fluorescent starter consisting of a master switch circuit, an ignition circuit and a time control circuit, wherein the electronic fluorescent starter matches with the ballast to turn on the fluorescent lamp; the control circuit turns the electronic fluorescent starter to the open circuit state when the fluorescent lamp is turned on; the brightness compensation circuit improves the intensity of light from the fluorescent lamp.

Abstract: A control circuit for a gas discharge lamp according to the present invention includes a transformer having a primary run winding, a primary start winding and a secondary winding. The primary run winding is coupled to a source of an AC run signal. The secondary winding is coupled to the gas discharge lamp. A current sensor is coupled in series with the gas discharge lamp to sense current flow through the lamp. A high frequency oscillator is coupled to the primary start winding for providing a high frequency start signal to the primary start winding. In a start phase, the oscillator provides the high frequency start signal to the primary start winding to initiate ionization of the gas discharge lamp. Once the gas has sufficiently ionized in the lamp, the control circuit switches from the start phase to a run phase by removing the high frequency start signal from the primary start winding and applying the AC run signal to the primary run winding.

Abstract: A ballast includes an inverter for providing an AC voltage to a discharge lamp. As the lamp approaches end-of-life, a DC voltage component develops across the lamp. The ballast includes circuitry for monitoring the condition of each of the cathodes by measuring this DC voltage component. After a predetermined increase in this DC voltage component, the inverter is disabled in order to prevent excessive heating of the cathodes. The inverter is also disabled as a result of a resonant or near resonant mode condition of a tank circuit caused by an open circuit condition or a leaking lamp.

Abstract: Included in a ballast circuit arrangement for a gas discharge lamp is a ballast transformer arrangement receptive of an input power signal and providing an output, ballast voltage. Further included is a pulse transformer having a secondary winding in serial circuit with the lamp for impressing a high voltage, hot restrike starting pulse across the lamp. A bypass capacitor is coupled to the ballast transformer for being charged by the ballast voltage. A hot restrike starting circuit for pulsing a primary winding of the pulse transformer comprises a serially connected starting capacitor and resistor coupled across the bypass capacitor; and a circuit for discharging the starting capacitor including, in serial circuit, the primary winding of the pulse transformer and a current switch having a control electrode responsive to a control signal.

Abstract: An improved fluorescent light ballast circuit extends the on/off life of a florescent lamp within a lighting circuit having a pair of series connected fluorescent lamps. The ballast circuit includes a DC pulse generation circuit, filtering and voltage regulation circuitry, a step-up voltage transformer, and a current altering circuit which alters the current within selected filaments within the lamps. The current altering circuit includes a diode and a coil winding which connect across a filament within one of the fluorescent lamps. The net effect of the current altering circuit is to increase the voltage supplied across the lamp connected to the current altering circuit so that the voltage levels across both lamps are balanced.

Abstract: A lighting circuit, which is lit with a voltage with a square wave, has a DC booster circuit, a bridge type DC-AC converter and an inductor provided at the subsequent stage of the DC-AC converter. A metal halide lamp is connected in series to the inductor. Another inductor and a capacitor are provided between the DC booster circuit and the DC-AC converter. A series circuit of a resistor and a diode is connected in parallel to the second inductor. This structure generates a resonance voltage having a high peak value to compensate for a re-ignition voltage of a discharge lamp which is produced when the polarity of the square-wave voltage is switched, thereby preventing the lighting failure of the discharge lamp immediately after the lighting starts.

Abstract: Method for operating a ballast for discharge lamps. The ballast comprises a rectifier for rectifying and filtering an AC line voltage, with the rectified voltage being smoothed with a capacitor and fed to an inverter, wherein the inverter drives a resonant lamp circuit that includes a gas discharge lamp, with the frequency of the inverter being generated by a voltage controlled oscillator and a control circuit, so that during normal operation of the lamp, the inverter frequency is chosen according to the current value of the rectified voltage, and during start-up of the ballast, the inverter frequency is lowered from a high starting frequency, while being continuously monitored to ensure the latter does not fall below a minimum frequency, with the value of the minimum frequency depending on the value of the rectified voltage, thus decreasing the dependence of the light flux on the rectified voltage and assuring a safe start-up process.

Abstract: An electronic ballast for powering at least two rapid start, parallel connected fluorescent lamps. Associated with each lamp is a serially connected choke and capacitor combination. A train of pulses of alternating polarity having a fundamental frequency, which is generated by an inverter, is applied to each serially connected combination. Each combination is characterized by a resonant frequency which is other than an odd harmonic of and at least two times and preferably .sqroot. 5 times greater than the fundamental frequency. Reduction in filament heating, following lamp ignition, is provided through the addition of voltages applied to each filament which are substantially out of phase with each other.

Abstract: A modulated electronic ballast for driving a gas discharge lamp includes a full wave rectifier for supplying a modulating signal to a series fed parallel resonant circuit including two transistors. Inductors are provided on both the hot and neutral alternating current power source lines for shielding the power source from electromagnetic interference and providing transient protection. A biasing circuit supplies a small direct current to the resonant circuit for retaining the resonant circuit in a continuous oscillating mode during substantially zero voltage valleys of the modulating signal. A diode is provided across the base and collectors of each transistor in the resonant circuit for preventing over saturation and co-conduction.

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 and includes inductive means, 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 variable impedance as a function of its control electrode potential. 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 power-supply and control circuit is provided for driving a fluorescent lamp from a low-voltage DC power source such as a battery. In typical lamp-driving circuits, a step-up transformer is used to apply well known magnetic techniques to achieve the low-to-high voltage conversion required by the lamp. The present invention uses a new approach, applying piezoelectric characteristics of certain ceramic materials to replace the magnetic transformer. Resonant characteristics of such ceramic materials permit them to be self-resonated. A DC-to-AC converter 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. The feedback signal is applied to the switching regulator to produce in the lamp a regulated current and, hence, a regulated lamp intensity.

Abstract: A monolithic MOS gate driver chip is described for driving high side and low side power MOSFETs in a gas discharge lamp ballast circuit. The chip includes a timer circuit for generating a square output at the natural frequency of resonance of the lamp ballast. Dead time circuits are provided in the chip to prevent the simultaneous conduction of both high side and low side MOSFETs. The chip may be housed in a right pin DIP package.

Abstract: A starter for a fluorescent lamp selectively conducts current from an AC power source through a ballast and cathodes of the lamp during one half cycle of conducted current from the AC power source. Thereafter and during the same on half cycle of current the starter ceases conducting current substantially instantaneously when the current is of a predetermined level. The resulting di/dt generates a starting voltage pulse from the ballast sufficient to ignite the plasma. The starting pulse occurs when the AC voltage across the cathodes exceeds an ignition voltage of the plasma. Preferably the starter employs a thyristor which has a predetermined holding current at least equal to the predetermined level to allow the inherent commutation of the thyristor to create the di/dt. The current conducted by the thyristor heats the cathodes prior to igniting the plasma.

Abstract: A system for energizing a fluorescent lamp by a current having an adjustable level of magnitude that is independent of the voltage across the fluorescent tube, which current is non-pulsing with the polarity being periodically changed at the conventional, 60 Hz rate of the AC power line by an electronic commutator, which commutator provides switching of the polarities at very sharp rise times, allowing use of relatively small components with the low frequencies, and the power factor of the input current is processed to a desired power factor. The constant current magnitude is adjustable over a wide range, which current settings are independent of the AC power line voltage and independent of the voltage across the lamp.

Abstract: The invention relates to a circuit arrangement for igniting a high-pressure discharge lamp (L), provided with input terminals (C,D) for connection to a commutating supply source with a square-wave supply voltage; a pulse-generating circuit (IV) provided with a voltage-dependent breakdown element (3) and with a voltage-raising network (2) formed by a network of rectifiers and capacitors; a pulse transformer (1); and an electrical connection between a secondary winding (12) of the pulse transformer and lamp connection terminals (E,F). The voltage-raising network (2) is in addition provided with inductors means (21, 22). The result of this is that a strongly increased voltage is available across the breakdown element substantially instantaneously after each commutation of the commutating supply voltage.

Abstract: A DC power supply for a gas discharge lamp includes a high voltage starting circuit for supplying high voltage pulses to effect initial energization of a gas discharge lamp, a lower voltage running circuit for supplying a desired average lamp operating current at a substantially constant current to the gas discharge lamp, and a transformer having a primary connected in the high voltage starting circuit and a secondary connected in the lower voltage running circuit. The transformer provides an inductance which acts as a current source inductor to supply current to the gas discharge lamp.

Abstract: A control apparatus for a fluorescent lamp for detecting an end-of-life state of a fluorescent lamp for making it possible to take suitable countermeasures. In the control apparatus, a load circuit is formed of a capacitor connected between filaments of a fluorescent lamp and a choke coil connected in series with the filament, and there are provided a detection coil for detecting a tube current flowing through the load circuit and a detection circuit receiving an output voltage of a rectifier circuit rectifying the output of the detection coil for detecting a rise in the output voltage occurring when the output frequency of an oscillation circuit is modulated by a modulation circuit.

Abstract: A nearly pure neon is described along with a method of operating the lamp. A phosphor is coated on the lamp wall. By properly stimulating the neon, ultraviolet light may be emitted, that can stimulate the phosphor to a first light emission. The lamp may then be operated to produce a visible light emission that is the result of neon emission or of intermediate combinations of the neon and phosphor emissions. A single neon lamp may then produce in one instance, an amber color, or in other instance, a red color without the cold environment problems typical of a mercury based lamp. The output efficiency is enhanced when the lamp is formed as an aperture lamp. The narrow source is also useful as a source in reflector and lens systems. High pressure neon lamps offer a small source size, direct color with no filtering, good tolerance of impact and jarring, moderate cost, and increased vehicle styling potential.

Abstract: An electronic ballast is provided with a built-in timed electric power saver and with photoelectric switching for high-pressure mercury vapor, metallic vapor and sodium vapor lamps. The electronic ballast with the built-in timed saver and photoelectric switching for high-pressure mercury vapor, metallic vapor and sodium lamps includes an electronic circuit having as a principle the obtaining of an increase in the frequency of the electric power distribution network. This increase is accomplished by means of a switching that results in a current limiting electronic device, which also is able to incorporate a timed electric power saver, the utilization of a single equipment for various lamp lower ratings, a photo-sensitive element for control of the lamp switching in accordance with the lighting level of the installation site and an ignitor for lamps requiring a voltage higher than the rated one.