Abstract: A plurality of cold cathode fluorescent lamps (CCFLs) for a backlight of a display device are connected, each in series with a respective variable inductance, in parallel to an AC supply from a power converter. Each variable inductor comprises a first inductor in series with the CCFL, a second inductor inductively coupled to the first inductor, and an AC switch for selectively shorting the second inductor. A capacitor in parallel with the first inductor forms a resonant circuit tuned to the AC supply frequency when the switch is open. Each switch is opened and closed with a controlled duty cycle to provide individual control of an average current of each CCFL.

Abstract: A circuit arrangement (1) for operating a high-pressure gas discharge lamp (2) is described. The circuit arrangement (1) has an igniting-circuit circuit arrangement (3) having a capacitor (C) able to be connected via two terminals (a3, a4, x1, x2) to a voltage supply unit (5), which capacitor (C) is connected in parallel with a primary winding (TP) of a transformer (T) by means of a switching element (SG) that becomes conductive above a given voltage. The circuit arrangement (1) also has a lamp-circuit circuit arrangement (4) in which the high-pressure gas discharge lamp (2) is connected on one side, via a secondary winding (TS) of the transformer (T), to a terminal (a1, x1) for connection to the voltage supply unit (5) and on the other side, via an inductive element, to a second terminal (a2, x2) for connection to the voltage supply unit (5).

Abstract: In a lamp lighting ballast which generates a lamp lighting signal for a lamp, provided is a striation elimination circuit to increase the lumen output frequency for elimination of visual striations which may occur within the lamp. An even harmonic signal generator is configured to generate an even harmonic waveform, and an injection point is configured to receive the even harmonic signal into the lamp lighting system. The injection point is located at a location wherein the even harmonic signal alters the lamp lighting signal from a symmetric signal configuration to a high content even harmonic signal configuration prior to being received by the lamp.

Abstract: A discharge lamp lighting circuit supplies an AC power for lighting a discharge lamp. The discharge lamp lighting circuit includes a power supply portion for supplying the AC power to the discharge lamp and a control portion for controlling the magnitude of the AC power. The power supply portion includes a series resonance circuit including transistors, a transformer, a capacitor and an inductor and a bridge driver for driving the transistors. The control portion controls the bridge driver so that the AC power increases intermittently. Thus, as the temperature of electrodes can be increased while suppressing the temporal average value of the supplied power within a rated power, the movement of a luminous point at the time of lighting the discharge lamp with a high frequency can be suppressed.

Abstract: A pulse booster circuit (10) comprises a first pulse transfer path (41) and a second pulse transfer path (42) extending between input terminals (11a; 11b) and output terminals (12a; 12b). A series arrangement of a capacitor (20and a first breakdown switch (13) is connected between said two input terminals (11a; 11b). A series arrangement of a second breakdown switch (14) and a primary winding (31) of a transformer (30) is connected in parallel to said capacitor (20). A first output winding (32)of said transformer (30) is incorporated in said first pulse transfer path (41), while a second output winding (33) of said transform (30) is incorporated in said second pulse transfer path (42).

Abstract: A charging circuit has a battery 12, switching element 14, and resistor 16 for current detection arranged on the primary side of transformer 10. Diode 18 and capacitor 20 for storing electric power are arranged on the secondary side of transformer 10. In a normal state, the ON/OFF states of switching element 14 are repeated corresponding to output signals U1, U2 of two comparators 28, 30. However, if switching element 14 stays on or off longer than a prescribed period of time for some reason, the status of switching 14 will be switched forcibly by an auxiliary sequence of the logic parts in control logic 42.

Abstract: A lamp drive circuit includes an electronic switch in series with the lamp and a source of DC voltage, a control input of the switch being pulse-width-modulated by a control circuit which includes a temperature-sensing circuit for reducing the pulse-width-modulation duty cycle when lamp temperature exceeds a predetermined temperature. The temperature-sensing circuit may include a thermal switch in series with one of two parallel-connected resistors in a timing circuit. Duty cycle may also be automatically adjusted in response to changes in the source voltage.

Abstract: A resonant switching converter comprising a first pair of series connected switches comprising a high side switch and a low side switch coupled across a DC input voltage, there being a first switched node between the switches; a second pair of series connected switches comprising a high side switch and a low side switch coupled across a DC bus, there being a second switched node between the switches; a DC bus capacitor coupled across the DC bus; the first and second switched nodes adapted to have a load coupled therebetween; the high side switch of the first pair of switches supplying current to the load from the DC input voltage, the low side switch of the first pair of switches being switched opposite the high side switch of the first pair of switches and providing a re-circulation path to allow bi-directional current flow through the load; the high side switch of the second pair of switches supplying current to the load from the DC bus capacitor, the low side switch of the second pair of switches being swi

Abstract: A double-ended, DC-AC converter supplies AC power to a load, such as a cold cathode fluorescent lamp used to back-light a liquid crystal display. First and second converter stages generate respective first and second sinusoidal voltages having the same frequency and amplitude, but having a controlled phase difference therebetween. By employing a voltage controlled delay circuit to control the phase difference between the first and second sinusoidal voltages, the converter is able to vary the amplitude of the composite voltage differential produced across the opposite ends of the load. The converter may be either voltage fed or current fed.

Abstract: In fluorescent lamp lighting, it is required that when the lamp reaches its end of life there has to be some mechanism to shut down the power supply to the lamp for safety. In the present invention, an apparatus is proposed to fulfill this requirement. This invention comprises of a lamp, means to sense currents at the lamp filaments and the imbalance of the currents is detected and turn off the power source to the lamp. Several embodiments are included to illustrate the execution of this invention.

Abstract: A driving device is provided, which includes: a switching unit directly connected to a first voltage from a source external to the driving device; a transforming unit indirectly connected to the switching unit for transforming the first voltage into a second voltage and applying the second voltage to a light source; a signal transmitting unit indirectly connected to the switching unit and transmitting a driving voltage for driving the switching unit based on a control signal; and an inverter controller outputting the control signal to the signal transmitting unit.

Abstract: A master-slave control architecture for inverters includes a master control circuit board which has a master control unit to output a plurality of frequency signals of the same phase and same frequency so that driving units on a plurality of separated slave control circuit boards on the rear end can be driven synchronously by the frequency signals to control electricity input of transformation units to transform voltage for outputting. Thereby the frequency of the driving electricity of the discharge lamps can be synchronized to maintain uniform luminance.

Abstract: An electronic device for starting and/or re-starting a power-driven device such as a lamp, bulb or lighting fixture includes an input stage, a rectifier stage, a power factor correction stage with total harmonic distortion correction, and a coil device comprising a wound coil having a primary winding of multistranded wire. The circuit may automatically adjust to a range of loads, and/or it may provide an auto-ranging line voltage. In an embodiment, the input stage accepts an AC input signal, the rectifier stage converts the AC input signal to a DC signal, and the coil device converts the DC signal to an AC output signal. The device may also include a frequency adjustment circuit that adjusts the frequency of the AC output signal to assistance in the performance of a restart function.

Abstract: A ballast (20) for powering one or more gas discharge lamps (70,72,74,76) comprises an inverter (200), an output circuit (300), and an arc protection circuit (400). Arc protection circuit (400) monitors an electrical signal within the output circuit (300). When an arcing condition occurs at the ballast output connections (302,304,306,308,310), the electrical signal includes a high frequency component having a fundamental frequency that is much greater than the normal operating frequency of the inverter (200). In response to the high frequency component exceeding a predetermined threshold, arc protection circuit (400) disables the inverter (200) for a predetermined shutdown period. Arc protection circuit (400) also provides a restart function for periodically attempting to ignite and operate the lamps.

Abstract: A separately-excited inverter circuit includes: an oscillator which generates a high-frequency voltage pulse by mixing a high-frequency voltage pulse of a first frequency and a high-frequency voltage pulse of a second frequency different from the first frequency; and a transformer drive part which buffers an output signal of this oscillator, and inputs the signal to a primary side of a transformer. The inverter circuit includes a capacitor which is connected in parallel with an output of a secondary side of the transformer. When used for lighting the backlight of a liquid crystal display, the present invention can improve the lighting characteristics of the backlight with a long cold-cathode tube.

Abstract: A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps is described. A common-mode choke is used between the cold cathode fluorescent lamps. The common-mode choke balances the currents respectively flowing through the cold cathode fluorescent lamps.

Abstract: A circuit for charging a photoflash that preferably reduces the average input to the switching regulator in an efficient fashion is provided. The regulator includes a transformer. The transformer includes a primary winding and a secondary winding. The switching regulator also includes a switch that closes at the beginning of a first portion of the switching cycle and opens at the end of the first portion of the switching cycle. The second portion of the cycle may be to allow the secondary winding to release current into the load. The switch is adapted to allow the current to build up in the primary winding when the switch is closed. The switching regulator may also include a delay circuit that introduces a delay between the end of the second portion of the cycle and the beginning of the first portion of the next switching cycle.

Abstract: The present disclosure introduces a simple method and apparatus for converting DC power to AC power, and, specifically, to single-ended inverter circuits for driving discharge lamps such as a Cold Cathode Fluorescent Lamp (CCFL) or an External Electrode Fluorescent Lamp (EEFL). Among other advantages, these circuits offer nearly symmetrical voltage waveform to drive discharge lamps when the duty cycle is close to 50%. They also eliminate the high current and high voltage resonant capacitor on the primary side, and reduce the voltage rating of a primary switch to twice the input voltage without the need for snubber circuits. The recommended inverters can be used to efficiently drive discharge lamps at low cost, particularly for applications with a narrow input voltage range. The lamp current can be regulated through the duty cycle modulation of the main switch.

Abstract: A precision voltage control circuit applicable to a PWM (Pulse Width Modulation) circuit can offer CCFL (Cold Cathode Fluorescent Lamp) or EEFL (External Electrode Fluorescent Lamp) tubes a stable high frequency voltage or current, so that each CCFL or EEFL tube can get an appropriate compensation current and an optimal emitting efficiency and enhance its emitting quality. The circuit also has an overload current, low current, and overload voltage and low voltage protective circuit to protect the CCFL or EEFL tubes from being injured. The circuit can also be applied to the TFT LCD TV or other large LCD panels, and develops the best display effect of each LCD tube.

Abstract: A power supply apparatus includes an inverter controller, a power transforming part and a connecting part. The power transforming part converts a direct current supplied from the inverter controller into an alternating current to output first and second polarity currents. The connecting part outputs the first and second polarity currents to first and second end portions of a load through first and second terminals, respectively and has a third terminal to receive a sensed signal in response to the first or second polarity currents so as to output the sensed signal. The first terminal is spaced apart from the second terminal by a first insulating distance, and the third terminal is spaced apart from the first or second terminals adjacent to the third terminal by a second insulating distance. Therefore, the sensed signal is independent of the output power, thereby increasing the sensing efficiency.

Abstract: A device comprising energy saving circuitry incorporated within lighting systems of the type utilizing discharge lamps, wherein the circuitry includes at least one transformer having a primary and secondary windings oppositely wound to establish different fields of polarity. The primary winding is connectable across a supply voltage and the secondary winding is connected in series with the discharge lamps lead. A switching assembly is associated with each of the one or more transformers and is operative in a first position to connect the primary winding across the supply voltage, wherein a voltage of an opposite polarity is induced across the secondary winding. In a second operative position the one or more switch assemblies serve to disconnect the primary winding from across the supply voltage and to shunt the primary winding, so that voltage across the secondary winding is zero (v).

Abstract: The lamp lighting circuit prevents a malfunction in which a lamp is tuned on momentarily during an initial stage of the power input. When the power source is lit, the malfunction prevention circuit prevents the activation of the oscillation circuit and/or the driving circuit 3a until when the output control circuit 5 starts normal operation and outputs the output control signal that controls the lighting/non-lighting of the lamp. When a lamp lighting command is input to the output control circuit, the output of the oscillation circuit is transmitted to the power control element via a driving circuit, and the power control element is driven. Consequently a voltage is generated on the secondary side coil of a boosting transformer so that the lamp 1 is lit.

Abstract: Systems and methods are disclosed that facilitate sensing a pulse in a ballast circuit for a lamp when the lamp is in an end-of-life (EOL) stage or when the lamp is experiencing an arcing conduction condition, such as may occur when a contact between the lamp and its holder is compromised. Upon sensing the pulse, a microcontroller may distinguish between EOL and arcing conditions based on detected pulse width(s), and may initiate an appropriate response. For instance, if the pulse is due to an arcing event, the microcontroller may interrupt lamp operation for a brief period before restarting the lamp to mitigate the arcing condition. If the pulse is caused by an EOL condition, the microcontroller may place the lamp in a preheat or restarting mode to hasten lamp failure. In either case, responses to the sensed pulse mitigate the occurrence of dangerously high lamp temperatures that may damage lamp sockets.

Abstract: The present invention relates to a circuit arrangement for operating at least one electric lamp (LP) having a drive circuit (16), which has at least one terminal for a system voltage (UN) on the input side and at least one terminal for the at least one electric lamp (LP) on the output side; the drive circuit (16) having a control unit (18) and a step-up converter having a step-up converter inductor (L2) and a switch (S1), and the control unit (18) being designed to operate the step-up converter in a discontinuous mode, in which the current (IN) through the step-up converter inductor (L2) has gaps, the duration (?t) of these gaps being varied. It also relates to an operating method for at least one electric lamp (LP) using such a circuit arrangement.

Abstract: A control circuit for an inverter for driving a fluorescent lamp includes a first triangular wave signal generator for use in analog dimming control, and a second triangular wave signal generator for use in burst dimming. The first triangular wave signal generator oscillates at a frequency higher than that of the second triangular wave signal generator. A semiconductor substrate on which the control circuit is integrated is partitioned into at least two areas by a fixed potential wiring. A circuit block including the first triangular wave signal generator is placed in one of the areas, and a circuit block including the second triangular wave signal generator and the comparator for burst dimming is placed in the other area.

Abstract: An anti-cycling luminaire control system may detect repeated lamp-off conditions and interrupt power to the lamp and provide an indication of lamp cycling after a predetermined number of lamp-off conditions has been detected. The control system also provides a cool-off period after a lamp-off cycling event is detected during which time restarting of the lamp is inhibited. If the lamp does not restart after multiple restart attempts and cool-off periods, the system determines that a fault condition exists, and may provide a fault alert. The system may provide for shut-off or dimming of the lamp during the night after a portion of the night has passed. This delayed turn-off may be varied according to the length of the night. Starting and dimming the lamp at a zero voltage crossing of the line current can reduce stress on luminaire and control system components and reduce maintenance.

Abstract: A plasma-generation power-supply device includes a transformer connected to an alternating-current power-supply, a rectifier connected to the transformer, an inverter connected to the rectifier, a reactor inserted in series in a power line of an ozonizer that is supplied with power from the inverter, and a controller that controls the inverter. The controller detects the current flowing to the ozonizer with a current detector and provides a control that keeps power applied to the ozonizer constant.

Abstract: A floating driving device for illumination includes a illumination unit having a first terminal and a second terminal. A first driver is electrically coupled to the first terminal of the illumination unit, for applying AC voltages to the first terminal. A second driver is electrically coupled to the second terminal of the illumination unit, for applying AC voltages to the second terminal in such a manner that the AC voltages at the first terminal and the second terminal are out of phase.

Abstract: A lower-cost and more precise control methodology of regulating the output voltage of a Flyback converter from the primary side is provided, which works accurately in either continuous voltage mode (CCM) or discontinuous mode (DCM). The methodology can be applied to most small, medium and high power applications such as cell phone chargers, power management in desktop computers and networking equipment, and, generally, to a wide spectrum of power management applications. Two highly integrated semiconductor chips based on this control methodology are also described that require very few components to build a constant voltage Flyback converter.

Abstract: System and method for driving a cold-cathode fluorescent lamp. The system includes a control subsystem configured to generate one or more control signals, and a power supply subsystem configured to receive the one or more control signals and a DC input voltage, convert the DC input voltage to an AC output voltage, and send the AC output voltage to a cold-cathode fluorescent lamp. If the DC input voltage is lower than a predetermined threshold, the system for driving the cold-cathode fluorescent lamp is turned off in response to the one or more control signals.

Abstract: A method of driving a lamp that uses a DC to AC inverter that is connected to a primary winding of a transformer is disclosed. The inverter frequency is variable, and in one embodiment, may be controlled by a voltage controlled oscillator. Circuitry is included that monitors the phase relationship between a voltage across a secondary of the transformer and a current through the primary of the transformer. The circuitry monitors the phase relationship and adjusts the inverter frequency, such as by adjusting voltage controlled oscillator, so that the phase relationship is maintained at a predetermined relationship.

Abstract: A ballast according to the present invention operates in an ignition state, a warm-up state, and a steady state for igniting and powering a lamp. The ballast comprises an igniter that ignites the lamp during the ignition state and a switching power inverter, for example, a full bridge DC-AC inverter implemented with MOSFET switching transistors, that powers the lamp during the warm-up and steady states. The switching power inverter, which drives the igniter, operates at a first switching frequency during the ignition state and operates at a second switching frequency during the steady state. Preferably, the first switching frequency, which in one exemplary embodiment is in the kHz range, is higher than the second switching frequency.

Abstract: A step voltage controlling device and method for High Intensity Discharge (HID) light dimming applications includes an autotransformer, voltage sensing block, current sensing block, pulse forming block, microprocessor control unit (MCU) block and plural three switch blocks which allows an instantaneous variation of the voltage applied to the load which is controlled to be synchronized with the load current zero crossing point.

Abstract: An inverter circuit for discharge lamps for multi-lamp lighting in which the value of a negative resistance characteristic of a fluorescent lamp is controlled, and an excessively set reactance is eliminated by causing a shunt transformer to have a reactance exceeding the negative resistance characteristic. Two coils connected to a secondary winding of a step-up transformer of the inverter circuit are arranged and magnetically coupled to each other to form a shunt transformer for shunting current such that magnetic fluxes generated thereby cancel each other out. Discharge lamps are connected to the coils, respectively, with currents flowing therethrough being balanced. Each discharge lamp is lighted because a reactance of an inductance related to the balancing operation which is in an operating frequency of the inverter circuit, exceeds a negative resistance of discharge lamps.

Abstract: An inductor for performing a chopper operation by turning on or off a first switching element MOSFET Q1 and obtaining an increased voltage is arranged on the secondary side of a transformer 112 and on the basis of the turn ratio of the transformer 112, a high voltage at the time of stable lighting can be obtained from a DC power source 111 at a low voltage Vin. Further, when the on-duties of the first and second switching elements MOSFET Q1 and Q2 constituting an inverter circuit are made almost similar, the timings of application of the power to both ends of a lamp 144 can be made similar, so that the life span of the lamp can be improved.

Abstract: An inductive power supply system for providing power to one or more inductively powered devices. The system includes a mechanism for varying the physical distance or the respective orientation between the primary coil and secondary coil to control the amount of power supplied to the inductively powered device. In another aspect, the present invention is directed to an inductive power supply system having a primary coil and a receptacle disposed within the magnetic field generated by the primary coil. One or more inductively powered devices are placed randomly within the receptacle to receive power inductively from the primary coil. The power supply circuit includes circuitry for adjusting the power supplied to the primary coil to optimize operation based on the position and cumulative characteristics of the inductively powered device(s) disposed within the receptacle.

Abstract: A discharge lamp lighting apparatus for supplying high frequency high voltage to an excimer discharge lamp comprises a boasting transformer having a core, a secondary side coil and a pair of primary side coils; a DC power source; and switching elements, wherein a duty ratio of an electrically conductive period to an operational cycle of each of the switching elements is 30% or less, a turn ratio of the secondary side coil to each of the primary side coils is 25 or less, a difference between a first length of a first axial direction area where each of the primary side coils are wound, and a second length of a second axial direction area where the secondary side coil is wound, is 18% or less of the first length or the second length, and a leakage inductance associated with magnetic coupling between the primary side coils and the secondary coil is 0.2% to 0.7% of a primary side coil inductance.

Abstract: The present invention uses one or more transformers disposed between an inverter driver to drive a plurality of lamps. Each transformer has a first coil and a second coil magnetically coupled to each other. Each of the first and second coils has an input end and an output end. The input end of the first coil is operatively connected to the input end of the second coil for receiving an input current. Each of the first and second coils has a capacitor connected between the input and output ends. The output ends of the first and second coils are used to provide output current in two separate current paths. As such, the output end of a transformer can be separately connected to the input end of two lamps or two such transformers.

Abstract: An efficient and flexible current-mode driver delivers power to one or more light sources in a backlight system. In one application, the current-mode driver is configured as an inverter with an input current regulator, a non-resonant polarity-switching network, and a closely-coupled output transformer. The input current regulator can output a regulated current source in a variety of programmable wave shapes. The current-mode driver may further include a rectifier circuit and a second polarity-switching network between the closely-coupled output transformer and a lamp load. In another application, the current-mode driver delivers power to a plurality of light sources in substantially one polarity by providing a regulated current to a network of time-sharing semiconductor switches coupled in series with different light sources coupled across each semiconductor switch.

Abstract: Disclosed are a power supplying apparatus, a backlight assembly and an LCD apparatus having the same. A control section outputs a switching signal so as to control an output of a constant current supplied to a lamp unit in response to on and/or off signals and a dimming signal and a switching section controls an output of a direct current voltage source in response to the switching signal. A power outputting section provides an alternating current voltage source having a constant voltage to the lamp unit. A sensing section senses variation of a power supplied to the lamp unit and a detecting section compares a sensing signal with a predetermined reference signal to output a detecting signal to the control section, thereby maintaining the constant current to be supplied to the lamp unit. Accordingly, the LCD apparatus may prevent deterioration of an image and damage of circuit thereof.

Abstract: A ballast lamp circuit and method of operation is disclosed. The ballast lamp circuit comprising an inverter circuit and cathode heating circuit, wherein a lamp current, generated by the inverter circuit, is inversely proportional to a lamp cathode voltage generated by the cathode heating circuit.

Abstract: A power conversion device has a series circuit of a main switching element and a sub-switching element connected to both ends of a DC power supply, an insulating transformer, and control circuits. The main switching and sub-switching elements are alternately turned on and off by the respective control circuits such that voltage generated in the secondary coil is subjected to smoothing rectification and supplied to a load. The insulating transformer includes a primary coil, and the main control circuit takes voltage of the primary coil as signal voltage to cause the main switching element to turn on and off such that DC voltage supplied to the load is constant. The sub-control circuit turns on the sub-switching element when the voltage at both ends of the sub-switching element becomes lower than a reference voltage or when the voltage of the primary coil exceeds a predetermined value.

Abstract: A ring balancer comprising a plurality of balancing transformers facilitates current sharing in a multi-lamp backlight system. The balancing transformers have respective primary windings separately coupled in series with designated lamps and have respective secondary windings coupled together in a closed loop. The secondary windings conduct a common current and the respective primary windings conduct proportional currents to balance currents among the lamps. The ring balancer facilitates automatic lamp striking and the lamps can be advantageously driven by a common voltage source.

Abstract: A resonant transformer is disposed at a stage following an inverter for inverting the polarity of a voltage applied to a discharge lamp. A parallel resonant circuit is formed by a resonant capacitor and a primary winding of the resonant transformer, and a periodic voltage applying section is connected to the parallel resonant circuit. The periodic voltage applying section is operated at a frequency that causes resonance in the parallel resonant circuit, thereby applying a high AC voltage to the discharge lamp in a period in which discharge is started in the discharge lamp.

Abstract: A lighting system employs a pair of ballast input stages (21) operable to oscillate at different oscillating frequency (f1, f2) upon an initial powering of the ballast input stages (21). The lighting system further employs a pair of ballast output stages (23) for establishing an open circuit voltage across the ballast output stages (23) in response to an absence of a loading of lamps (10) across the ballast output stages (23). The light system further employ means for, subsequent to the initial powering of the ballast input stages (21) and in response to the absence of the loading of the lamps (10) across the ballast output stages (23), impending any parasitic loading across the ballast output stages (23) from phase locking the oscillating frequencies (f1, f2).

Abstract: An inductive power supply system for providing power to one or more inductively powered devices. The system includes a mechanism for varying the physical distance or the respective orientation between the primary coil and secondary coil to control the amount of power supplied to the inductively powered device. In another aspect, the present invention is directed to an inductive power supply system having a primary coil and a receptacle disposed within the magnetic field generated by the primary coil. One or more inductively powered devices are placed randomly within the receptacle to receive power inductively from the primary coil. The power supply circuit includes circuitry for adjusting the power supplied to the primary coil to optimize operation based on the position and cumulative characteristics of the inductively powered device(s) disposed within the receptacle.

Abstract: A cold cathode flat fluorescent lamp and a driving method for a cold cathode flat fluorescent lamp are provided. The cold cathode flat fluorescent lamp includes a lamp, a transformer and a full-bridge circuit. The lamp has at least a first electrode having a first voltage and a second electrode having a second voltage. The transformer has a primary side and a secondary side, and the full-bridge circuit is used for driving the lamp. In addition, the transformer is connected to the lamp on the secondary side and is connected to the full-bridge circuit on the primary side.

Abstract: A ballast (100) for powering at least one gas discharge lamp (30) at two selectable light levels includes a sensing transformer (120) and a detector circuit (200). Detector circuit (200) provides an output voltage that is dependent on the states of two on-off switches (S1,S2) interposed between the ballast (100) and a conventional AC source (20). The output voltage of the detector circuit (200) is used to control the illumination level of the lamp (30).

Abstract: A discharge-lamp control device for lighting a discharge-lamp includes two electrodes, first and second driving units to supply power to the discharge-lamp through the electrodes, respectively. Each driving unit includes a transformer having primary and secondary coils and a capacitor connected in parallel to the secondary coil. The first driving unit has impedance characteristics with a minimum impedance at a first frequency and a maximum impedance at a second frequency lower than the first frequency. The second driving unit has impedance characteristics having a minimum impedance at a third frequency and a maximum impedance at a fourth frequency lower than the third frequency. The first frequency is set to be higher than the third frequency. The second frequency is set to be lower than the fourth frequency. An operating frequency of the driving circuit is selected within a frequency bandwidth from the fourth frequency to the third frequency.

Abstract: A control section is used to control a DC-to-AC converter circuit to perform lighting control of a discharge lamp. A transformer, switching elements, and a capacitor for resonance are included. The switching elements are driven and serial resonance of the capacitor and the inductance component of the transformer or an inductance element is produced. Before the discharge lamp is turned on, control is performed to cause the driving frequency of the switching elements to gradually approach Foff and to supply a start signal to the discharge lamp. Once the discharge lamp is turned on, control is performed to continuously change the driving frequency from f1 assumed before the discharge lamp is turned on to f2. A residence time in a frequency range lower than Fon is secured then the frequency is shifted to a frequency range fb higher than Fon, or an inductive range fb.