Abstract: A backlight module that includes a lamp and a single side driving inverter that is coupled to one end of the lamp. The single side driving inverter is configured to control an operating current of the lamp to be within 80% to 100% of a saturation luminance current. The lamp has a characteristic such that when the operating current is lower than the saturation luminance current, the lamp luminance increases as the operating current increases, and when the operating current is substantially equal to or higher than the saturation luminance current, the lamp luminance does not increase as the operating current increases.

Abstract: A circuit and a method for driving a light source are provided. The circuit for driving a light source according to exemplary embodiments of the present invention includes a converting unit which supplies an electric current required for driving a light source and a converter controller which detects the current output from the converting unit and compares the detected current to a reference current to control the current of the converting unit based on the comparison result. Also included are a light source driver which receives the controlled current from the converting unit and converts the current into a pulse current to drive a light source and a pulse signal generator which generates a pulse signal to be applied to the light source driver.

Abstract: The invention relates to a DC-DC converter having over-current/over-voltage protection function and an LED driving circuit using the same. The DC-DC converter adjusts a width of a switching pulse outputted from a Pulse Width Modulation (PWM) controller to control on/off durations of a switch, thereby providing a controlled level of voltage to a load. The DC-DC converter includes a microcontroller for detecting a voltage, and if the detected voltage is greater than a reference voltage, generating an alarm signal. The DC-DC converter further includes a digital-analogue converter for outputting a voltage of 0V and an analogue dimmer for generating a control signal that changes an ‘on’ duration of the switching pulse outputted from the PWM controller to 0 and providing the control signal to the PWM controller.

Abstract: A semiconductor integrated circuit that has a quick response to changes in source/drain electrode voltage having an LDMOS transistor. The transistor has a second conduction type first well region formed in a first conduction type semiconductor substrate; a first conduction type second well region formed in the first well region; a second conduction type third well region formed in the second well region; a drain region formed in the second well region; a source region formed in the third well region; a gate electrode formed through a gate insulating film over the third well region between the drain region and the source region; and an insulating layer formed between the gate electrode and the drain region. Parasitic capacitances between the semiconductor substrate and the source region and those between the substrate and the drain region are respectively in series.

Abstract: An illumination device comprising at least four luminous units (1, 2), the light emitted by at least two of the four luminous units (1, 2) being suitable for being mixed to form white light. Moreover, an apparatus (3) for dimming at least one of the four luminous units (1, 2) is provided. White light having a desired color temperature (CCT) and a high color rendering index can be generated by means of the illumination device.

Abstract: A lamp contains a lamp voltage conversion circuit that is entirely within a base for converting a line voltage at a lamp terminal to an RMS load voltage at a light emitting element. The voltage conversion circuit includes a forward clipping circuit with a three-terminal thyristor that forward clips a load voltage to define the RMS load voltage, and a time-based pulse source that provides pulses the trigger conduction of the three-terminal thyristor at constant time intervals that are independent of the magnitude of the line voltage.

Abstract: A backlight system drives multiple lamps using balanced groups of serially-connected lamp transformers. A plurality of lamp transformers is divided into multiple transformer groups. Primary windings of the lamp transformers are coupled in series in each transformer group. Lamps are coupled to secondary windings of the lamp transformers. The transformer groups are arranged in a parallel configuration. One or more balancing transformers couple the transformer groups to a common power source. The balancing transformers divide a common current from the common power source into multiple balanced currents for the respective transformer groups.

Abstract: A driving circuit for driving an electroluminescent lamp is disclosed. The driving circuit includes an alternating current (AC) voltage generator for providing at an output an AC output voltage waveform for driving an electroluminescent lamp and a controller for controlling the phase and polarity of the AC output voltage waveform. The controller is operable to reverse the phase and polarity of the AC output voltage. In one embodiment, the AC voltage generator includes a transformer.

Abstract: A two-wire dimmer for control of a lighting load from an alternating-current (AC) power source includes a semiconductor switch, a power supply, and a control circuit. The power supply includes an energy storage input capacitor that is able to charge only when the semiconductor switch is non-conductive. The control circuit continuously monitors the voltage on the input capacitor and automatically decreases the maximum allowable conduction time of the semiconductor switch when the voltage falls to a level that will not guarantee proper operation of the power supply. The dimmer of the present invention is able to provide the maximum possible conduction time of the semiconductor switch at high end (i.e., maximum light intensity) while simultaneously ensuring sufficient charging time for proper operation of the power supply, and hence, the dimmer.

Abstract: A ballast control integrated circuit for driving at least one gas discharge lamp comprising a first oscillator circuit for producing a first oscillating signal; a driver circuit for driving first and second output transistors connected in a half bridge configuration; the driver circuit being provided with pulsed signals derived from the first oscillating signal for generating pulsed drive signals for driving the first and second transistors; and a dimming control circuit responsive to a dimming input signal to drive the driver circuit such that the driver circuit provides the pulsed drive signals in bursts thereby to dim the lamp in dependence on the level of the dimming input signal. The ballast control integrated circuit also provides overcurrent and overvoltage sensing and allows master/slave operation.

Abstract: A device for lighting a discharge lamp has a drive circuit to feed alternating power the discharge lamp, and a control circuit. The control circuit controls the drive circuit by a drive pulse to perform a burst dimming control over the discharge lamp. The control circuit has detector, subtractor, a digital filter, and pulse generator. The subtractor subtracts the detected lamp current by the detector from a reference value. The digital filter integrates the output of the subtractor as an integrator. The pulse generating means generates the drive pulse based on the output of the digital filter. The lighting time period has a first time period immediately after a start of the lighting time period and a second time period following the first time period. The control circuit sets the reference value to a target current value in the second time period. The control circuit increase the reference value in the first time period to the target current value until an end of the first time period.

Abstract: A system and method for illuminating a light source, particularly a vehicle light source. The light source receives a voltage signal causing the light source to be illuminated. A triggering circuit detects the voltage signal. If the voltage signal is at or below a predetermined value, then the triggering circuit maintains a switch closed so that the light source continuously receives the voltage signal. If the voltage signal goes above the predetermined value, the triggering circuit opens and closes the switch in a pulsed manner where the voltage signal applied to the light source is on during the pulses and off between the pulses so that the brightness of the light source remains substantially constant.

Abstract: A current of the same amount or in a constant ratio is applied to each of a combination of a blue light emitting diode having a small wavelength variation and a green light emitting diode having a large wavelength variation. With this, as an amount of applied current increases, an oscillation wavelength of the green light emitting diode having the large wavelength variation changes from a long wavelength side to a short wavelength side and mixes with a blue color of the blue light emitting diode having the small wavelength variation to gradually change chromaticity as a whole. When desired chromaticity is obtained, the amount of the current is fixed.

Abstract: A method of converting a line voltage to a desired RMS load voltage in a lamp includes the steps of pulse width modulating a load voltage with a pulse width modulation circuit, triggering conduction in the pulse width modulation circuit independently of a line voltage magnitude with a time-based signal source that defines a duty cycle of the pulse width modulation circuit, and adjusting the RMS load voltage to the desired RMS load voltage by adjusting the triggering of conduction in the pulse width modulation circuit based on a comparison of the RMS load voltage to a reference.

Abstract: A lamp includes a voltage conversion circuit that converts a line voltage to a desired RMS load voltage. The voltage conversion circuit is entirely within a lamp base and uses pulse width modulation to define the RMS load voltage. The voltage conversion circuit includes a bridge that supplies the RMS load voltage to a light emitting element, a switching transistor that pulse width modulates a current supplied to the bridge, a timer connected to a gate of the switching transistor to turn the switching transistor on and off at a rate that defines the RMS load voltage, an analog-to-digital converter that converts the RMS load voltage to a digital signal, a comparator that compares an output from the converter to a preset reference value, and a circuit that adjusts the timer in response to an output from the comparator.

Abstract: The present invention can provide a cold cathode tube lighting apparatus capable of causing no pulsating current, intermittent oscillation, or flicker-off even under light load, stably keeping a cold cathode tube lighting, safely tuning on the same, and the like. The present invention is characterized by supplying a rectangular wave voltage Vs to a series resonance circuit 12 and by driving the cold cathode tube 8 with an output of the series resonance circuit. The series resonance circuit has a constant that makes a maximum output voltage with respect to a predetermined tube current value exceed a tube voltage VL of the cold cathode tube when the cold cathode tube is turned on and in an operating load range of the cold cathode tube of negative resistance characteristic. A control circuit 15 controls a cold cathode tube current IL to a predetermined value while the cold cathode tube is in a lit state.

Abstract: An input line filter separates an ac sinusoidal power source from a power switching stage having a series switching section and a clamp switching section. Both the series switching section and a clamp switching section include complementary pairs of high power and high speed MOSFETs. The series switching section is connected in series between the input line filter and the inductor of an output load filter between the power switching stage and a load. The clamp switching section is connected to shunt the inductor and load. Synchronous operation is achieved by alternately operating the series and clamp switching sections to conductive conditions at a high pulse width modulation frequency. The duty cycle is selected to provide a sinusoidal output waveform with a desired amplitude. A microprocessor based programmable controller provides control signals for alternate conduction of the series and clamp switching sections.

Abstract: A circuit for controlling two switches assembled in anti-parallel, comprising in series between two terminals of the anti-parallel assembly, two identical control stages respectively dedicated to each switch and between which is interposed a common impedance setting a phase angle for the turning-on of the switches, each stage comprising: a controllable current source for providing a current to a control electrode of the concerned switch; a capacitor for storing a supply voltage of at least the current source; an element of activation/deactivation of a the current source according to the voltage across the stage capacitor; and an assembly for discharging the capacitor.

Abstract: A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

Abstract: A lighting circuit of confirming the insulation property of an HID lamp and a lighting circuit upon starting the operation of the HID lamp to previously prevent damages of the main circuit, and starting discharge at the lowest starting voltage in accordance with the characteristics of the HID lamp, comprising a control section having an insulation property confirming section for confirming that the current does not flow in a state of applying a predetermined voltage to the main circuit before applying the starting voltage to an HID lamp and a starting voltage variable controller for increasing the secondary voltage generated from the step-up transformer of the starting circuit stepwise after confirming the insulation property.

Abstract: It is an object to provide a xenon discharge lamp lighting device with few or no lamp startup lighting failures, even when a xenon discharge lamp is near the end of its useful life. In the xenon discharge lamp, when a lamp voltage increases, from the ending point of the rush current supply time period, occurring upon starting a xenon discharge lamp lighting igniter, for a preset specified time T, the input power is increased in accordance with the lamp voltage increase amount, whereby constant power control is provided thereafter.

Abstract: A plurality of lighting ballasts (12, 14, 16) draw power from a single DC bus signal. A power factor correction circuit (10) rectifies and smoothes AC power to produce the DC bus signal. In order to prevent damage to the ballast (12) when a lamp (18) dies or is removed, the ballast (12) includes an AC switch that senses damaging conditions and responds by changing a resonant frequency of the ballast (12). The AC switch operates in 2-3 second cycles. While it is operative, it shunts current away from inductors (38, 40) of the ballast (12) causing a resonant frequency of the ballast (12) to change. At the end of the cycle, the switch turns off, but if a load fault is still present in the ballast (12) it activates again. Preferably, the AC switch has a response time of approximately 500 &mgr;s.

Abstract: A plurality of lighting ballasts (12, 14, 16) draw power from a single DC bus signal. A power factor correction circuit (10) rectifies and smoothes AC power to produce the DC bus signal. In order to prevent damage to the ballast (12) when a lamp (18) dies or is removed, the ballast (12) includes an AC switch that senses damaging conditions and responds by changing a resonant frequency of the ballast (12). The AC switch operates in 2-3 second cycles. While it is operative, it shunts current away from inductors (38, 40) of the ballast (12) causing a resonant frequency of the ballast (12) to change. At the end of the cycle, the switch turns off, but if a load fault is still present in the ballast (12) it activates again. Preferably, the AC switch has a response time of approximately 500 &mgr;s.

Abstract: A ballast for at least one electric incandescent lamp, having at least two switching elements (T1, T2) that are coupled to one another with the formation of a first tie point (VP1), a drive circuit (10) with at least one output for driving the switching elements (T1, T2) with the aid of a drive signal that has a pulse duty factor (d) and an operating frequency (fs), and with an input for a dimming signal (Ud), and a power transformer (Ü) whose primary side (L1) is coupled to the first tie point (VP1), it being possible to connect the electric incandescent lamp (LA1; LA2) to the secondary side (L2) thereof, the drive circuit (10) being designed to vary the pulse duty factor (d) and the operating frequency (fs) of the drive signal as a function of the dimming signal (Ud).

Abstract: A circuit and method for providing a linear power to a load uses pulse modulation technique where the frequency and pulse width of the pulse width modulated waveform driving the load are varied simultaneously. In one aspect of the disclosure, a pulse width modulator circuit is responsive to a command drive signal for producing the pulse width waveform the width of the pulses varying accordingly. In addition, a frequency control circuit that is also responsive to the command drive signal provides a control current to the pulse width modulator circuit wherein the frequency of the waveform is varied as the pulse widths are varied.

Abstract: A non-blinking direct current fluorescent lamp circuit includes a switch, a bridge rectifier, a voltage regulation circuit, a filter capacitor, an ignition circuit, a contact points converter, a ballasting circuit, and a pole exchange circuit. The switch is a common switch or a contact switch circuit. Thus, the non-blinking direct current fluorescent lamp circuit does not produce electromagnetic radiation, has a steady illuminance, can be started at one time, has a higher working efficiency, can save the energy, can be worked safely, has a higher reliability, and has a longer lifetime.

Abstract: A method and apparatus is disclosed to reduce power consumption of a load. In one embodiment a power control system selectively routes power directly to a load or to a power reduction device. A delay may occur prior to introduction of the power reduction device to fully energize the load. The power reduction device may operate in conjunction with signal modification device. The signal modification device modifies the signal provided to the load to achieve desired operation of the load. In one embodiment the power reduction device comprises a step-down transformer and the signal modification device comprises a capacitor. In one embodiment the power reduction device is selected to remove unwanted frequency components from the signal provide to the load. In various other embodiments the power control system may be configured to stagger start the load to minimize the peak draw of the load.

Abstract: A power-saving lamp is constructed to include a lamp head, a bulb fastened to the lamp head, a polygonal light emitting circuit assembly suspended from a bracket in the lamp head within the bulb, the polygonal light emitting circuit assembly having LEDs in each of the peripheral sidewalls thereof, and a power control circuit board mounted in the lamp head and electrically connected between the lamp head and the polygonal light emitting circuit assembly to convert input AC power from the lamp head into the desired working voltage for the polygonal light emitting circuit assembly.

Abstract: A metal halide magnetic/electronic ballast with a compensation function for adjustment in autotransformer output voltage, which applies the compensation in various steps of voltage, to maintain the power constant. The metal halide ballast provides constant monitoring of the autotransformer input voltage, enabling the level to be stepped by triac switching. The triac switching is controlled by a switching control provided by a microcontroller. Less components are required, making the present invention simpler, less expensive to manufacture and more reliable.

Abstract: A discharge lamp operating apparatus includes a discharge lamp and a driving circuit of the discharge lamp. The driving circuit can vary power to be supplied to the discharge lamp and has a function to turn off the discharge lamp at a supplied power value above a supplied power value at which unstable discharge occurs in the discharge lamp.

Abstract: An elongated gas-discharge lamp having a controllable illuminated length may be formed with a dielectric barrier discharge, in which the position of a discharge voltage is dependent, for example, on a discharge gap 6′ which varies over the length of the lamp 1′. The varying discharge gap allows, for example, bar displays or quantitative brake warning lights to be provided.

Abstract: A dimmer for controlling AC power to a lighting load provides a leading power factor by initiating conduction through an electronic switch at each zero crossing of the line current. The dimmer delivers current to the lighting load in a sequence of pulses where each pulse corresponds to a portion of one AC half wave. A variable resistance that alters a voltage signal delivered to an integrated circuit permits the user to determine the duration of each pulse and thus vary the power delivered to the lighting load. The dimmer is provided with over current protection.

Abstract: An AC controller which provides programmable switching of AC power flow, together with producing a source of DC power for operating the AC controller. The AC controller is connected in series with only one side of the AC power source and the AC load. The AC controller utilizes a thyristor for AC power control switching. During the operation, the AC controller steals a small portion of each half-cycle of the AC power to provide DC power to the AC controller. The AC controller enables the flow of AC current by providing a gate current pulse at any predetermined time during the half cycle. Once the thyristor is ON, the AC current flows through the thyristor until the AC cycle is at or near zero. To provide an OFF state, the AC controller does not provide a gate current pulse. The AC controller uses an microcontroller for the programmable capability.

Abstract: A circuit for supplying AC voltage and current to a gaseous discharge lamp upon the application of DC voltage and current, the circuit comprising: a transformer including a first and a second primary windings; a first capacitance means, coupled across the primary windings to define a resonant circuit; a start-up current source coupled to a drive terminal; first and second transistors coupled to the drive terminal; at least one drive winding coupled on one end to the drive terminal and coupled on the other end to the base of one of the transistors; and first and second current-blocking devices, in one embodiment a diode and in another embodiment a transistor, each current-blocking device configured so as to block a current from flowing into the emitter element of one of the transistors.

Abstract: A ballast includes a resonant load circuit having a resonant inductance and a resonant capacitance. The load circuit couples a.c. current to a gas discharge lamp. A self-oscillating complementary converter circuit of the ballast induces a.c. current in the resonant load circuit. The converter circuit includes a pair of switches serially connected between a d.c. voltage bus and a reference bus. Respective reference nodes of the switches are interconnected at a common node through which the induced a.c. current flows, and respective control nodes of the switches are substantially directly interconnected. A gate drive circuit controls the switches. The gate drive circuit includes a drive winding connected to the control nodes. The drive winding is mutually coupled to the resonant inductance for sensing current therein, and an inductor is serially connected to the drive winding and to the common node.

Abstract: The invention relates to a circuit arrangement for operating at least one discharge lamp, which has a half-bridge inverter (T1, T2, A) with a downstream load circuit (LD, CR) and has a half-bridge capacitor (CK) and also a monitoring apparatus for monitoring a change in the voltage drop across the half-bridge capacitor (CK) which is caused by the occurrence of a rectifying action in the at least one discharge lamp LP. According to the invention, the monitoring apparatus has a first RC element (R1, C1) and a second RC element (R2, C2), which are connected to one another by a threshold switch (DC), and means for detecting the switching state of the threshold switch (DC). The first RC element (R1, C1) is connected to the center tap of the half-bridge inverter, and the second RC element (R2, C2) is connected to the half-bridge capacitor (CK).

Abstract: A supply circuit for a fluorescent tube installation with a high-voltage transformer (T) which is connected, input-end, to a supply voltage with a frequency of several hundred Hz, and which is formed without an air gap. To replace the air gap in the transformer, an electronic regulator (EST) is nonetheless used in the supply circuit, which emulates the current-limiting function of an air gap. The frequency of the supply voltage is between 300 and 800 Hz, preferably 400 Hz. As these frequencies are higher than the usual network frequency of 50/60 Hz, the size and weight of the transformer can be considerably reduced.

Abstract: An alternating current—pulsating direct current converter (6) is adopted for eliminating unfavourable effects of feeder line, used in the electronic transformer of bromine tungsten filament lamp (5), such as half-wave, full-wave and bridge-type converters. Input signal is an alternating current one. After output signal is transformed, the effect of impedance change of feeder line (4) is eliminated, thus making output match and stabilisation.

Abstract: A power supply for high voltage, low current gas discharge tubes such as neon, argon, and mercury vapor. A free running, flyback oscillator, converts D.C. voltage energy into radio frequency energy by means of a compact, ferrite transformer and associated circuitry. The primary winding is tuned by a resonant capacitor and driven by a power transistor. A high voltage, centertapped winding of a ferrite transformer drives the gas tube load directly. A feedback winding arranged across the transistor base and emitter junction sustains oscillation and controls the drive level of the transistor by means of a regulating circuit which controls the amplitude of the current. Oscillator starting is achieved by means of an on-off switch which supplies a single starting pulse to the power transistor or by means of a time delayed starting pulse.

Abstract: A discharge lamp operating apparatus has a glass envelope for defining a discharge space and a pair of electrodes which are hermetically sealed within the glass envelope and are opposed to each other. The apparatus includes (1) generation element for generating a waveform signal having an acoustic resonant frequency for exciting a mode, in which a discharge arc between the pair of electrodes is straightened and (2) modulation element for modulating the waveform signal so that a polarity of the center line of the waveform signal is alternately changed at a lower frequency than the acoustic resonant frequency. If the value of the amplitude of the waveform signal from peak to peak is .alpha., and the effective value of the modulated waveform signal is .beta., then the depth of modulation .alpha./.beta. at the beginning of operation is equal to or less than the depth of modulation .alpha./.beta. at an operation under rated condition.

Abstract: A circuit for operation of a semiconductor light source having terminals for connecting a source of power and output terminals for connecting the semiconductor light source. The circuit is also provided with a controlled current generator and is also concerned with a signal head incorporating the circuit. The controlled current generator is controlled by the current flow through the semiconductor light source and the current supplied by the controlled current generator.

Abstract: A circuit for supplying AC voltage and current to a gaseous discharge lamp upon the application of DC voltage and current, the circuit comprising: a transformer including a first and a second primary windings; a first capacitance means, coupled across the primary windings to define a resonant circuit; a start-up current source coupled to a drive terminal; first and second transistors coupled to the drive terminal; at least one drive winding coupled on one end to the drive terminal and coupled on the other end to the base of one of the transistors; and first and second current-blocking devices, in one embodiment a diode and in another embodiment a transistor, each current-blocking device configured so as to block a current from flowing into the emitter element of one of the transistors.

Abstract: An AC discharge lamp having a constricted arc, and powered through a unidirectional ballast with a unidirectional current, is described. The AC lamp operates as a DC lamp. One method of achieving the constriction of the arc of this lamp is to modulate the DC input power to the discharge lamp to reduce the adverse effects of DC operation. The mechanism mixes the chemicals with an acoustically induced flow.

Abstract: A device for operation of a discharge lamp in which a dielectric barrier discharge lamp can discharge with high efficiency. A discharge lamp of the outside electrode type, a dielectric barrier discharge excimer lamp type, or the like, is operated by applying a lamp voltage of 1 kV to 10 kV with a periodic waveform by an operation circuit. In this lamp, within bulb including a dielectric, at least one type of rare gas is hermetically enclosed in a given amount. A dielectric barrier is located between at least one electrode and the gas, and a discharge is produced in the bulb via this dielectric barrier. The rise time or fall time of a waveform which represents a main energy supply time in the periodic waveform, is fixed at greater than or equal to 0.03 .mu.s and less than or equal to 9 .mu.s. Furthermore, the distance between the waveform which represents the main energy supply and a adjacent waveform which represents an adjacent main energy supply is greater than or equal to 3.4 .mu.s.

Abstract: The present invention discloses a multiple flash/single lamp circuit for fast sequential strobing. More particularly, the present invention comprises a flashlamp, a pair of capacitors, a voltage multiplier and regulator to charge the capacitors, a pair of trigger circuits to discharge the capacitors and a controller to selectively activate each trigger circuit to activate the flashlamp.

Abstract: A d.c. voltage source delivers the voltage at its output terminals. This voltage is converted to a higher voltage level by a d.c./d.c. converter. This higher voltage level forms the input voltage to a controlled power-supply circuit. From this, the power-supply circuit forms the supply voltage and supply current for a high-pressure gas-discharge lamp to supply it with burning energy. A control circuit is provided to control the power-supply circuit, and an ignition circuit (9) is provided for the ignition. The power-supply circuit is controlled by the control circuit so that the high-pressure gas-discharge lamp is operated with a defined overload when illumination is started. In this context, the overload is defined so as to prevent flickering or light-saddles. The overload is controlled by the control circuit as a function of the state of the high-pressure gas discharge lamp.

Abstract: A gas discharge lamp is provided having a ballast control element and suppressible igniter. The igniter is chosen to superimpose an ignition pulse onto the initial AC ballast cycle or cycles provided to the lamp. The secondary coil of the igniter transformer is initially shorted until sufficient voltage is applied to the igniter. This causes a switch arranged across the secondary coil to open. A voltage detector coupled to a primary winding of the igniter transformer senses the amount of voltage applied from the ballast. Once that amount has been detected, the secondary winding is no longer shorted and the igniter can initially ignite the lamp during a peak of the initial cycle or cycles from the ballast. After the lamp has been initially ionized/discharged, or after a pre-defined set of discharges, the switch remains closed for the duration of each and every ballast cycle. Thus, the igniter is suppressed from the ballast output, and the ballast alone provides lamp discharge.

Abstract: A discharge vessel with a ceramic wall is filled with inert gas and metal and is ignited and operated by an electronic circuit including a half bridge converter with an LC circuit which, when the lamp is not ignited, enters an oscillation state near a resonance frequency which lies near the third harmonic of the switching frequency of the half bridge converter. The vessel encloses a cylindrical discharge space of diameter D and length L, wherein L.ltoreq.D.ltoreq.1.2 L.

Abstract: An apparatus for operating a high intensity discharge lamp that minimizes discharge arc curvature to form a straight discharge arc and thereby eliminate variations in the discharge arc color caused by cataphoresis is disclosed. The apparatus outputs a synthesize wave having a waveform with a frequency component of the acoustic resonance frequency to excite a mode straightening the discharge arc, and a waveform of a frequency less than the acoustic resonance frequency whereby the polarity of the waveform having a frequency less than the acoustic resonance frequency changes. The acoustic resonance frequency is determined by the speed of sound in the discharge space, and the length of the discharge space intersecting the discharge arc.

Abstract: An electronic ballasting circuit provides high efficiency ballasting for most common types of fluorescent lamps. The circuit consists of a half-bridge inverter providing a substantially squarewave voltage across a series-combination of an inductor and a capacitor. The fluorescent lamp is connected in parallel circuit with the capacitor in such a way that the current flowing through the capacitor also flows through the lamp cathodes, thereby providing continuous low voltage heating therefor. The values of inductance and capacitance are so chosen that the series-combination has a natural resonance frequency that is substantially equal to or lower than the lowest frequency component present in the squarewave voltage.