Abstract: A medium- and high-power frequency adjustable digital power system includes a switch switching circuit, an output sampling circuit, and a microcontroller. The switch switching circuit has a plurality of switches, receives an AC input power source and converts the AC input power source into an output power source. The output sampling circuit receives an output voltage and an output current of the output power source. The microcontroller receives the output voltage and the output current, and generates a plurality of control signals according to power information calculated by the output voltage and the output current to correspondingly control turning on and turning off the switches.

Abstract: A camera module includes a lens barrel, a driving coil disposed to face a target detection unit prepared on one side of the lens barrel, a driving device configured to provide a driving signal to the driving coil, and a position calculating unit including a first capacitor, configured to provide a ground for an alternating current (AC) signal to the driving coil, a second capacitor, connected to the driving coil to constitute oscillation circuit together with the driving coil, and a position calculating circuit configured to calculate a position of the lens barrel from a frequency of the oscillation circuit.

Abstract: This application includes a source for a wireless power transfer system including: sensing and measurement circuitry configured to process signals associated with a source resonator and a source impedance matching network including a tunable component; a PWM generator coupled with power transistors of an amplifier coupled with the source impedance matching network, wherein the PWM generator is configured to control a driving signal to drive the source resonator using the power transistors; and a controller coupled with the sensing and measurement circuitry to receive measured signals, wherein the controller is configured to control a component value or an operating point of at least one of the tunable component(s), and the controller is configured to modify operation of the PWM generator based on the measured signals to modify at least a phase of the driving signal while changing power delivered to the source resonator.

Abstract: Current sensors measure current flowing into and out of an inductive load such as a solenoid coil and provide signals to a processor when the difference between the two measured currents exceeds a threshold. A solenoid coil and electronic devices driving it are protected from damage caused by a short circuit at the connections to the coil.

Abstract: A light source device includes a discharge lamp including a pair of electrodes arranged to be opposed to each other in a hollow section in which a discharge medium is encapsulated and a driving device. The driving device includes a supplying unit configured to supply an alternating current having a frequency higher than 1 kHz to the pair of electrodes in a high-frequency period and a control unit configured to set at least a first frequency higher than 1 kHz and a second frequency higher than 1 kHz and different from the first frequency as the frequency of the alternating current, switch an alternating current having the first frequency and an alternating current having the second frequency in the high-frequency period, and control the supplying unit to repeat the high-frequency period to supply an alternating current to the pair of electrodes.

Abstract: A lighting system with reduced standby power according to the embodiment includes a main control unit to control a lighting device; a driver to supply the control signal to the lighting device; and an AC-DC converting circuit to supply power to the driver. A method of reducing standby power according to the embodiment includes charging a standby power supply unit with power in a normal mode; checking whether a lighting off signal is transmitted and switching off a lighting, and simultaneously, shutting off the power supplied from the AC-DC converting circuit when the lighting off signal is transmitted; changing an operation mode of a lighting device from a normal mode to a standby mode; checking whether a voltage of the standby power supply unit is less than a predetermined level; and charging the standby power supply unit when the voltage is less than the predetermined level.

Abstract: A method of operating a plasma processing device includes outputting a first RF power having a first frequency and a first duty ratio, and outputting a second RF power having a second frequency higher than the first frequency and a second duty ratio smaller than the first duty ratio. The outputting of the first RF power and the outputting of the second RF power are synchronized with each other.

Abstract: The transparent conductive film of the present invention is a transparent conductive film, comprising a transparent film substrate, and a first transparent dielectric layer, a second transparent dielectric layer and a transparent conductive layer that are formed on one or both sides of the transparent film substrate in this order from the transparent film substrate side, wherein the transparent conductive layer is patterned, the relation n2<n3<n1 is satisfied, wherein n1 is the refractive index of the first transparent dielectric layer, n2 is the refractive index of the second transparent dielectric layer, and n3 is the refractive index of the transparent conductive layer, the first transparent dielectric layer has a thickness of from 2 nm to less than 10 nm, the second transparent dielectric layer has a thickness of from 20 nm to 55 nm, and the transparent conductive layer has a thickness of from 15 nm to 30 nm.

Abstract: A method for providing universal voltage input to a solid state lighting fixture (140) supplied by an AC line voltage includes converting an analog voltage signal corresponding to the line voltage to digital values indicating a waveform of the line voltage (S312) and calculating slopes corresponding to rising edges of the waveform using select values of the digital values (S453). A value of the line voltage is determined based on the calculated slopes (S458).

Abstract: A power supply for an image intensifier, the power supply including a DC voltage source generating a photocathode voltage; a bright source protection (BSP) resistor in series with the DC voltage source; and an oscillator in parallel with the DC voltage source and the BSP resistor, the oscillator providing an AC voltage component, the AC voltage component having a fixed pulse width, the AC voltage component being coupled to the photocathode by a diode, the pulse width and shape of the AC voltage component on the photocathode being determined by the photocathode current.

Abstract: A driver circuit for a laser diode or other optical source comprises a controllable termination for a transmission line coupled between the driver circuit and the optical source, with the controllable termination being switchable between at least first and second termination configurations. The transmission line comprises a first conductor coupled to a first terminal of the optical source and a second conductor coupled to a second terminal of the optical source, and the driver circuit comprises a first current source configured to drive the first conductor, and a second current source configured to drive the second conductor. By way of example, the first termination configuration may comprise an alternating current (AC) termination configuration and the second termination configuration may comprise a direct current (DC) termination configuration.

Abstract: A technique of improving the life of a spark plug which generates spark discharge and AC plasma. A plasma ignition device includes a power control section which reduces AC power P after generation of AC plasma in an AC power supply period Sa during which the AC power P is continuously supplied to a spark plug within a maintainable power range Rp within which the AC plasma can be maintained.

Abstract: A display device with a touch sensor according to the present invention includes an active matrix substrate and a transparent counter electrode. On a first surface of the active matrix substrate, multiple pixel electrodes are arranged in matrix. The transparent counter electrode is opposed to the first surface of the active matrix substrate. The display device further includes a first circuit, a second circuit and a switching circuit. The first circuit supplies a voltage or a current to the transparent counter electrode for display purposes. The second circuit detects currents flowing from a number of points on the transparent counter electrode. And the switching circuit selectively connects electrically one of the first and second circuits to the transparent counter electrode.

Abstract: A mixer for mixing pulse voltage energy and electromagnetic wave energy in the same transmission line is provided with a first input terminal to which an electromagnetic wave is inputted, a second input terminal to which pulse voltage is inputted, a mixing output terminal from which the pulse voltage and the electromagnetic wave are outputted, a bar-shaped first conductive member of which one end is electrically connected to the second input terminal and the other end is electrically connected to an inner conductor of the mixing output terminal, a cylindrical second conductive member which surrounds the first conductive member with a gap therebetween and is disposed coaxially with the first conductive member and electrically connected to an inner conductor of the first input terminal, and a cylindrical third conductive member which houses the first conductive member and the second conductive member with a gap between the second conductive member and the third conductive member and is disposed coaxially with t

Abstract: An ablative plasma gun having a dual power source pulse generator is configured to generate a high voltage low current pulse and a low voltage high current pulse. A pair of electrodes are disposed and configured to receive the high voltage low current pulse, and to receive the low voltage high current pulse in response to the high voltage low current pulse.

Abstract: The invention relates to an electroluminescence (EL) element based on a particular zinc sulfide thick film with at least two planar electrodes, wherein at least one planar electrode is designed to be transparent. At least two AC voltage inputs are provided on each electrode at two points which are spaced apart. Moreover, the invention relates to methods for the production of the electroluminescence element and to the use thereof.

Abstract: A system for operating a fluorescent light is provided. The system comprises: a fluorescent lamp with at least one electrode having at least one corresponding heating filament; a filament signal power supply for providing a filament current signal having a filament current frequency, the filament signal power supply connected to create a filament current through the at least one filament; and a plasma signal power supply for providing a plasma power signal having a plasma power frequency, the plasma signal power supply connected to create a plasma current between the at least one electrode and a gas contained in the fluorescent lamp. The plasma power frequency is greater than the filament current frequency.

Abstract: An AC power feedback control device for a vacuum fluorescent display is provided. In the AC power feedback control device, the Class-D drivers are driven by the PWM controller so as to generate a sine wave voltage. After being filtered by the LPFs, the sine wave voltage is ready for filaments. The output voltage outputted by the filaments is detected by simple feedback elements so as to control and modulate the duty cycle of the PWM controller.

Abstract: An apparatus and method for driving a lamp are provided. In one embodiment, an inverter having four switching elements is split into two inverter arms that are deployed at separate terminals of a floating lamp structure to achieve even light output. A controller drives both inverter arms such that power switching lines do not cross the floating lamp structure. In one embodiment, the controller adjusts the brightness of the lamp structure by adjusting the phase difference between outputs of a first inverter arm relative to a second inverter arm. In one embodiment, the controller adjusts the brightness by symmetrically pulse width modulating the outputs of the first inverter arm and the second inverter arm.

Abstract: To provide a solar simulator which has a plurality of xenon arc lamps as a light source, in which a predetermined amount of light is stably obtained from each of the xenon arc lamps so that constant irradiance over a test plane is ensured. The solar simulator comprises a plurality of xenon arc lamps; a plurality of light amount sensors provided one for each of the xenon arc lamps; and a plurality of control circuits provided one for each of the xenon arc lamps, for controlling a current flowing through, or a voltage applied to, each of the xenon arc lamps, wherein a detection signal output from each of the light amount sensors is fed back to each of the control circuits to control the relevant control circuit, to thereby control the amount of light emitted from each of the xenon arc lamps.

Abstract: Provided are an apparatus for controlling a lamp driving, and a light unit. The apparatus comprises a trans-portion, a plurality of lamps, a first cable, and a current attenuator. The trans-portion outputs a first AC power and a second AC power. The plurality of lamps are lighted-on by the first and second AC powers. The first cable and a second cable transfer an output power from the transformer to both ends of the lamps. The current attenuator removes a deviation in currents input to both ends of the lamps.

Abstract: A method and a circuit arrangement are described for operating a discharge lamp is described, especially a high-intensity discharge lamp or lamps (HID) or UHP [ultra high performance]-lamp, which is/are distinguished by a first and a second operating phase with a higher first or a lower second frequency of the lamp AC, wherein the operating phases are activated alternatingly at defined intervals and for defined periods of time, in order to achieve a stable arc discharge and only a low burnout or rise in burning voltage of the lamp during its life by configuring certain forms of electrode tips. Furthermore, are described an illumination unit with a discharge lamp and such a circuit arrangement as well as a projection system with a projection display and such an illumination unit.

Abstract: A circuit for driving the current for inductive loads such as a electron beam deflection coil for an x-ray generator system. The circuit includes two selectable voltage levels which are provided by a high level voltage source and a low level voltage source or, alternatively, by a low level voltage source and a boosting converter. A plurality of switches for selecting the voltage source allow only one voltage source to be connected to the load at any given time, and for selecting the polarity of the current through the coil. The high level voltage source is selected when the load is charging or discharging. The low level voltage source is selected when the load is operating in a constant current mode, where a high frequency switching device uses the low level voltage source to generate a pulse width modulation waveform according to a reference current duty cycle to control the voltage across the load.

Abstract: A circuit for driving the current for inductive loads such as an electron beam deflection coil for an x-ray generator system. The circuit includes two selectable voltage levels provided by a high level and a low level source. A plurality of switches selects the voltage level and determines the polarity of the current through the coil. The high level source is selected when the load is charging or discharging. The low level source is selected when the load is operating in a constant current mode, where a high frequency switching device controls the voltage through the load by switching the low level source to generate a PWM waveform according to a reference current duty cycle. A feedback loop monitors the current through the load to adjust the duty cycle of the PWM waveform to more accurately control the current through the load.

Abstract: A method for reducing video display power usage by dithering the brightness. This method can be used to reduce power consumption without having an effect on the brightness of the display screen as perceived by the user or may further reduce the power consumed with a corresponding reduction of brightness.

Abstract: A power supply for applying a voltage to a scanning electromagnet for deflecting a charged particle beam has a first power supply unit having no filter and a second power supply unit having a filter. When an irradiation position of the charged particle beam in an irradiation object is moved, the first power supply unit, namely a power supply unit having no filter, is used to apply the voltage to the scanning electromagnet, so that an exciting current flowing in the scanning electromagnet can be changed in a short time. Further, when the irradiation position of the charged particle beam is maintained, the second power supply is used to apply a voltage whose pulsating component was removed to the scanning electromagnet, so that the exciting current flowing in the scanning electromagnet can be controlled precisely. Consequently, the charged particle beam can be applied uniformly to the irradiation object and an irradiation time of the charged particle beam to the irradiation object can be curtailed.

Abstract: A method of operating a discharge lamp includes modulation of lamp power with a first longitudinal mode frequency to reduce segregation of the vapor phase species within the arc tube. The first longitudinal mode excitation frequency is determined by the acoustic response spectrum observed at an upper region of the arc tube when operated vertically. A frequency in an arc-straightening frequency range may also be added to the input power to straighten and center the arc.

Abstract: Disclosed is a method for operating a high-pressure discharge lamp, a lighting apparatus, and a high-pressure discharge lamp apparatus each capable of operating the lamp at a power lower than the rated power without imposing excessive burden on the lighting circuit. To this end, when a detected lamp voltage (Vla) is below a predetermined level (S102: No), the current is supplied at a lower frequency than the rated frequency for a predetermined time period (S103 and S104 ).

Abstract: A discharge lamp driving circuit includes DC voltage input connections, lamp driving connections, bridge circuitry, and control circuitry. The bridge circuitry is connected to the DC voltage input connections and to the lamp driving connections and includes circuit elements which in one mode of operation deliver a higher frequency AC voltage to the lamp driving connections and in another mode of operation deliver a lower frequency AC voltage to the lamp driving connections. The control circuitry is connected to control the bridge circuitry selectively as either a half-bridge to deliver the higher frequency AC voltage to the lamp driving connections during starting or a full-bridge to deliver only the lower frequency AC operating voltage to the lamp while the lamp is operating normally after starting. A low frequency driver and a high frequency driver are connected to drive the bridge circuitry.

Abstract: An apparatus and method for operating an arc discharge lamp which can be hot restarted is described. The method involves providing low microwave power after the lamp ballast is disconnected from the lamp. The microwave power is modulated such that conductivity is maintained within the lamp as the lamp cools. Restarting the lamp is accomplished by reconnecting the ballast at any time. In one embodiment, the apparatus of the invention includes an arc discharge lamp and ballast coupled together with a switch to turn the lamp on and off. A microwave power supply is connected in parallel with the ballast and is coupled to the lamp when the ballast is shut off. The invention allows for hot restart of the arc lamp without requiring a high voltage pulse.

Abstract: A high pressure gas discharge lamp is operated with normal output by at least predominantly low frequency energy supplied from a conventional power supply unit, and is operated at lower than 25 percent of the normal output by at least predominantly high frequency energy supplied from an electronic power supply unit. The electric output fed to the lamp is controlled. At any level of operation, a steady burning of the lamp for saving service life of the lamp is guaranteed. The switching arrangement, in addition to a conventional power supply unit, has an electronic power supply unit. The electronic power supply unit feeds the lamp with energy at a frequency which is higher than that of the energy supplied from the conventional power supply unit.

Abstract: An electroluminescence (EL) element lighting device for an EL element, includes a first circuit for self-oscillating to generate a first signal having a first frequency, and for gradually charging up said EL element in response to the first signal, and a second circuit for self-oscillating to generate a second signal having a second frequency, and for discharging the charge stored in said EL element in response to the second signal. The first frequency of the first signal is greater than the second frequency of the second signal, and the second signal is active only during a time interval less than 50% of each period of the second signal.

Abstract: A field emission device (100) having an electron emitter (101), for emitting electrons, an extraction electrode (102) proximally disposed with respect to the electron emitter (101), an anode (103) for collecting some of any emitted electrons is formed. Anode (103) is distally disposed with respect to the electron emitter (101). A transient current source (110) is operably coupled between the electron emitter (101) and a reference potential (107). Transient current source (110) provides a transient current to the electron emitter (101) to enhance response time for emission of electrons from the electron emitter (101) of the field emission device (100). A controlling input line (111) is provided for current controlling signals to the transient current source (110) with the controlling input line (111) being operably coupled to the transient current source (110).

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

Abstract: A power supply for an electroluminescent lamp includes a pair of inverters for alternately powering the EL lamp from a low voltage DC source. A first inverter is connected to a first electrode of the EL lamp and a transistor is connected between the first electrode and electrical ground. A second inverter is connected to a second electrode of the EL lamp and a second transistor is connected between the second electrode and electrical ground. A pulse generator connected to the inverters and the transistors operates the inverters and transistors to power the EL lamp alternately from one inverter and then the other. In one embodiment of the invention, the voltage across the EL lamp is referenced to ground and, in another embodiment, the voltage across the EL lamp is referenced to the voltage of the DC source.

Abstract: Cathodoluminescent display apparatus employing an electron source including a plurality of diamond crystallites. Image display apparatus employing an array of picture elements, each picture element having associated therewith an electron source including electron emitting diamond crystallites, is realized as a preferred embodiment.

Abstract: An emergency lighting system utilizing standard nonemergency circuitry to provide power to all of the light fixtures in a facility during a power failure. This emergency lighting system uses an electronic inverter to convert d.c. power stored in batteries to either a high or low frequency a.c. power which is supplied to the facility's standard light circuitry. The high or low frequency a.c. power generated by the inverter causes the output voltage of the ballast within each of the facility's fluorescent and/or HID lamps to decrease, thereby reducing the illumination intensity of each of these lamps and saving battery power. Since the incandescent, electroluminescent or L.E.D. exit signs of the facility are generally insensitive to a change in the frequency of the a.c. power, each of these lights continues to operate at full brilliance. Alternatively, a chopper regulator may be used to lower the average voltage level of the power provided to the facility's light circuitry.

Abstract: A dimming system provides power from a switch-controlled power source in series with a leakage auto-transformer to a compact fluorescent lamp. The system incorporates a high-frequency resonant converter that provides high voltages to strike and maintain an electric discharge in the lamp. The converter is loaded in parallel by the lamp, whose impedance damps the converter to stabilize lamp operation. An inductor, connected between the leakage auto-transformer and the resonant converter, isolates the switch-controlled power source from the high-frequency voltage. The system can be used with a variety of standard leakage reactance auto-transformers to provide full-range dimming of compact fluorescent lamps from 5 to 100 percent light output with minimal flicker.

Abstract: A lighting apparatus for a neon lamp includes a direct current power supply with a relatively low voltage output. The direct current power supply actuates a pulse oscillator to produce a narrow pulse voltage train output. The narrow pulse voltage train output is amplified and is supplemented by the signal output of a glow control cirucit to drive the neon lamp into operation. The signal output of the glow control cirucit can be a pulsating voltage signal or a constant voltage signal to correspondingly cause the neon lamp to blink or glow constantly.

Abstract: A method of and apparatus for supplying high frequency alternating current to a fluorescence lamp. For eliminating a so-called striation phenomenon, a direct current component is induced in the high frequency alternating current passing through a lamp (8). The circuit means inducing said direct current component comprise a capacitor (3), connected in series with the lamp and having a diode (4) or the like connected in parallel therewith.

Abstract: A full-bridge transistor inverter is connected at its DC supply-side with an energy-storing capacitor. The inverter's output terminals are connected in series between a source of AC voltage and a load; which load may be an electric motor, a fluorescent lighting system, etc. By controllably switching the transistors of the inverter ON and OFF at some rate higher than, but basically synchronous with, the frequency of the AC voltage, effective control of the flow of power between the AC source and the load is achieved. DC voltage on the energy-storing capacitor is obtained from the AC source and established by way of the timing of the switching action of the inverter.

Abstract: An inverter-type electronic fluorescent lamp ballast powers a fluorescent lamp with a sinusoidal current that is modified by insertion of a measured amount of properly phased third harmonic current, thereby attaining a lamp current crest factor that is substantially better than the 1.4 crest factor associated with a purely sinusoidally-shaped current.

Abstract: A ballasting system for powering an array of flourescent lamp assemblies, as in a sun tanning apparatus, comprises an electronic frequency converter adapted to convert ordinary 60 Hz power line voltage into two non-current-limited high frequency outputs: a first output of 400 Volt/30 kHz sinusoidal voltage provided between a first pair of distribution conductors, and a second output of 50 Volt/30 kHz sinusoidal voltage provided between a second pair of distribution conductors. Each lamp assembly comprises two mutually parallel-disposed series-connected fluorescent lamps. The 50 Volt/30 kHz voltage is provided to the one end of this assembly and is used by way of an isolation transformer means to provide cathode heating power for the two lamp cathodes located near that end.

Abstract: Apparatus for reducing the effects of beat frequencies in systems having multiple oscillators wherein a wide band frequency modulator operates to alter the frequency supplied by one of the oscillators at a rate high enough that any beat frequencies occur at rates undetectable to the human eye.

Abstract: Methods and apparatus are disclosed for supplying and controlling simmer current to a flashlamp 28. A direct current-to-direct current converter including a transformer 12, full-wave bridge rectifier 24, and first and second switching means 20 and 22 produces an output which is always higher than the maximum required by the flashlamp 28 at its lowest simmer current. The converter (12, 20, 22, 24) is coupled to flashlamp 28 through an inductor 26. The current I(s) through a pair of inductors 26, 30 is sensed by a lamp current sensing circuit 34 which turns the converter on or off, respectively, when a preselected minimum or maximum value is reached. The converter transformer 12 is maintained in its operating range by the switching of two devices such as power FET's 20, 22 so that one or the other of the two halves of the primary winding 14 is used alternately. The initial ionization of flashlamp 28 is provided by simmer trigger circuit 38.

Abstract: A system for driving a neon tube to form luminous bubbles and controlling the motion thereof in which a modulatable high AC voltage source is connected to control a pair of electronic switches in the primary circuit of a high voltage transformer which is connected to electrodes of said neon tube in such a way as to produce the luminous bubbles, which can be stationary or moved at varying speeds and direction by control of width and/or frequency of control pulses applied to the electronic switches. A memory stores predetermined patterns of the direction and speed of said luminous bubbles and microprocessor means for controlling said modulatable AC voltage in accordance with said predetermined pattern by said memory means to cause said luminous bubbles to move in said predetermined patterns of direction and speed. The memory may include a plurality of predetermined patterns stored, and selector for selecting one of said patterns and driving the neon tube therewith.

Abstract: A device for producing and controlling the flow rate of bubble-like ionization discontinuities (30) in a gas discharge tube (10) which includes means to produce an alternating current at a frequency between 1500 and 8000 Hz and a voltage between 2000 and 12000 V (16), a capacitor (36) in series with the tube to prevent direct current flow through the tube, and means to produce asymmetry (18) between the positive portion and the negative portion of the alternating current through the tube, the asymmetry being time asymmetry or wave shape asymmetry, the degree of asymmetry influencing the rate of apparent bubble flow through the tube and the direction of asymmetry influencing the direction of the apparent bubble flow through the tube.

Abstract: A fluorescent illuminator including a fluorescent lamp, a lamp housing, and a lamp power supply with a variable current output with a relatively fixed frequency at least an order of magnitude greater than line frequency and a non-integral multiple thereof. There are means for connecting the power supply to the lamp and also means for varying the current output of the power supply between a first, lowest level and a second, highest level to change the light intensity of the fluorescent lamp.

Abstract: A ballasting circuit for fluorescent lamps includes a series-connected current limiting ballast element and an electronic assist circuit. The ballast element has a high voltage side connectable to a commercial 110 VAC/60 hertz power source and a low voltage side connected in series with the lamp. The electronic assist circuit has a full wave bridge rectifier input means connected to the low voltage side of the ballast element and a transformer output means connected in series between the ballast element and the lamp. The electronic assist circuit generates a relatively high frequency, high voltage excitation signal prior to lamp conduction to assist in starting the lamp. After lamp conduction begins, the low voltage side of the ballast element drops to the normal operating voltage of the lamp and the excitation signal amplitude correspondingly drops, but is not eliminated, so as to maintain lamp operation with low frequency power supplied from the commercial power source.

Abstract: A high-pressure discharge lamp operating circuit performs a low-frequency AC operating at an early stage of operating and thereafter performs a high-frequency AC operation or DC operation during the steady-state of lamp operation. This circuit comprises a circuit for effecting a transition from the low-frequency AC operation to the high-frequency AC operation or DC operation either at the time which is a predetermined time period after the ignition of discharge before the high-pressure discharge lamp reaches the steady-state of operation, or after having detected at least one of predetermined lamp characteristics, thereby providing a stabilized light output.