Abstract: A circuit for reversing a voltage polarity on a first electrode and a second electrode may comprise a first inductor connected between the first electrode and a negative terminal of an external power supply. The positive terminal of the power supply is connected to the second electrode. A diode and a first capacitor are connected in series across the first and second electrodes so that the cathode of the diode is connected to the first electrode. A second capacitor and a switching device are also connected in series across the first and second electrodes. A second inductor is connected between the switching device and the anode of the diode.

Abstract: A dimming ballast for use with a phase control dimmer, and particularly a triac dimmer, includes an EMI filter selected with a high impedance to avoid excessive voltage and peak currents in the filter due to resonance with the phase controlled AC waveform at low conduction angles, when the load presented by the lamp is low. The EMI filter includes a filter capacitor connected at the output of a rectifier. The ballast also includes circuitry to sense the rectified DC voltage and to discharge the filter capacitor when the rectified voltage is at or near zero, to thereby keep the EMI filter loaded and prevent misfiring of the triac dimmer. In a favorable embodiment, the sensing and discharge function is carried out by a pre-conditioner of the switched-mode type.

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

Abstract: An electronic AC light dimmer, lighting system and method are disclosed that provide two-channel operation by allowing independent control of positive and negative half cycles of AC power. In one embodiment, the dimmer comprises a positive half-cycle control circuit for controlling an mount of current flowing through the dimmer during positive half-cycles and a negative half-cycle control circuit for controlling an mount of current flowing through the dimmer during negative half-cycles. In a further embodiment of the invention, the dimmer is wired to at least two light bulbs that are part of a common circuit, and a channel selection circuit. Preferably, the channel selection circuit comprises at least two diodes, each diode connected in series with one of the bulbs. The action of the dimmer and the diodes provides two channels, each channel being associated with either positive or negative half cycles.

Abstract: A discharge lamp lighting apparatus includes a voltage raising element for raising a DC input voltage, a pulse generator for varying the output voltage output by the voltage raising element is a pulse voltage having a given pulse width and outputting the pulse voltage, a bridge circuit for applying the pulse voltage to a discharge lamp, a voltage detecting element for detecting a voltage applied to the discharge lamp, a current detecting element for detecting a current running through the discharge lamp, an adder for adding a first amplification signal output by a first amplifier and a second amplification signal output by a second amplifier together, elements for delaying outputs from the amplifiers, and a pulse width modulator for controlling the pulse width of the pulse voltage.

Abstract: To control the color temperature of a sodium high-pressure discharge lamp, preferably having a sodium and xenon fill, which may also include mercury, without essentially affecting the color rendition index of the emitted light, or the light flux or intensity of light radiation emitted, the lamp is operated under pulsed conditions, in which the instantaneous pulse power of recurring power pulses, separated by a holding phase to prevent extinction of the lamp, is controlled. Preferably, the overall energy of any one of said power pulses and the intervening holding pulse is maintained essentially constant, for example by varying the frequency of sub-pulses or oscillations of which the sequential power pulses are constituted. A frequency and power controllable oscillator (1) is connected to the lamp (3) through a series LC network to effect such control, thereby permitting adjustment of color temperature and matching of the light output to selective color reflectivity of illuminated objects.

Abstract: To provide for optimum control of a sodium high-pressure discharge lamp operating under saturated operating conditions, such that the lamp will be operating stably and providing light output which is an optimum with respect to the color rendition index (Ra), light output or luminous flux, and color temperature, without regard to manufacturing tolerances or variations in power supply voltage, the energy supplied to the lamp is controlled with respect to a quotient formed of lamp voltage and lamp current (V.sub.L /I.sub.L), said quotient being determined with respect to optimum light values. The power supply for the lamp (3) either is a stabilized output voltage power supply (22) in which the output current is controlled, or an oscillator (32) providing bursts or power pulses (10, 10') formed of oscillations (11).

Abstract: A multi-color display unit includes at least a first and second plurality of dot-type light sources, such as LED or small lamps, which are arranged in different geometrical patterns and may be powered in any desired order or combination thereof. Each plurality of dot-type light sources may be of different colors or may include color filters in combination with one-color dot-type light sources to form a multi-color display unit. The geometrical arrangement between those dot-type light sources may include bar-type, and/or circumferences, parallel or intersecting, and a combination with other geometrical patterns.

Abstract: An electronic device for powering a gas discharge load (FL1) from a low frequency alternating voltage source (AVS). This device is drawing a current proportional to a voltage of the source (AVS) and is constituted by a resonant boosting circuit integrated into a power line voltage rectifier (BI,BRB) which performs boost switching and rectifying functions developed by and synchronized with a pulsating current drawn from the rectifier by a resonant oscillator circuit (RO1) equipped with a switching transistors (Q1,Q2) and adapted to energize the gas discharge load (FL1).

Abstract: A low component count and lightweight ballast usable with fluorescent lamp loads of widely different wattage has first and second inductors and first and second capacitors connected in a bridge circuit and can provide current regulation within a few percent for lamp loads between 14 Watt and at least 40 Watt. The two inductors can be wound on a single toroidal core for maximum compactness.

Abstract: The present invention describes a method and apparatus for a swept frequency switching gas discharge tube supply which produces a "crawling effect" in gas discharge tubes containing neon, argon or mercury gases or other gases and which has a means for eliminating the "bubble effect". To produce the "crawling effect", the driving frequency of the switching supply is swept from a higher frequency to a lower frequency thereby causing the excitation point to move from the electrodes on both ends of the dual electrode gas discharge tube to the center of the gas discharge tube. By varying the base switching frequency of the supply, the bubble effect which plagues some displays can be eliminated.

Abstract: A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current.

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 method and a ballast circuit are disclosed for operating a metal halide lamp particularly suited for horizontal applications that provides signals capable of being varied so as to control the power applied to the metal halide lamp while still providing a uniform arc. The ballast circuit has a filter which passes a selected band of frequencies for the operating signals of the metal halide lamp.

Abstract: A device for modulating and controlling the level of luminosity output by a lighting facility. The modulation may be of average current or voltage. The device modulates electrical power in a cyclical manner for input to the lighting facility, so that the resulting modulation of the luminosity output serves to exercise the eyes of persons exposed thereto. The average luminosity, and the amplitude and period of modulation can be set and adjusted by the user. The rate of modulation is sufficiently slow that the level of change of luminosity is accommodated by human eyes and is imperceptible through the eyes of persons exposed thereto. In one embodiment, an illuminance sensor is provided to read the actual illumination of a lighted object. The values of the illumination so read are fed back in the device to adjust the luminosity of the lighting facility, so that the object is illuminated in the desired cyclical manner.

Abstract: A circuit and method for controlling a power supply are disclosed, with specific application to dimming of a resonant inverter solid-state fluorescent lamp ballast. The control circuit produces a pulse train signal with pulses of variable duty cycle. The signal is integrated to provide a DC signal which the solid-state ballast uses to control the level of dimming of the lamp. When the duty cycle of the pulses is increased, the level of the DC signal increases, so that the ballast dims the lamp. Conversely, reduction of the pulse duty cycle increases the brightness of the lamp. The control circuit incorporates delay circuitry which suppresses the pulse output at powerup, so that the lamp starts at full intensity. Thereafter, the delay circuitry adjusts the pulse signal so that the lamp intensity is adjusted smoothly to the desired level.

Abstract: A circuit arrangement suitable for operating a low pressure mercury discharge lamp by means of a high-frequency pulsatory current comprising circuitry for generating a high-frequency pulsatory current from a supply voltage with a modulator for modulating the high-frequency pulsatory current into a substantially square-wave shape voltage with a current amplitude A, with a modulation frequency f and a duty cycle DC together with circuitry for adjusting the duty cycle DC and circuitry for adjusting the amplitude A.

Abstract: The present invention and its related methods of operation provide a wide range dimmable high frequency lamp ballast system having a resonant circuit associated with each lamp or lamp set for providing a resonant frequency which is substantially higher than the drive frequency at which the lamp or lamp set is driven, and means for automatically selecting a drive frequency to be a submultiple of the resonant frequency of the resonant circuit, the selection of a submultiple being dependent on lamp operating conditions.

Abstract: A circuit arrangement suitable for operating a low pressure mercury discharge lamp by means of a high-frequency pulsatory current comprising circuitry for generating a high-frequency pulsatory current from a supply voltage with a modulator for modulating the high-frequency pulsatory current into a substantially square-wave shaped voltage with an amplitude A, a modulation frequency f and a duty cycle DC together with circuitry for adjusting the modulation frequency f and circuitry for adjusting the duty cycle DC.

Abstract: A circuit arrangement suitable for operating a low pressure mercury discharge lamp by means of a high-frequency pulsatory current comprising circuitry for generating a high-frequency pulsatory current from a supply voltage with a modulator for modulating the high-frequency pulsatory current into a substantially square-wave shape voltage with a current amplitude A, a modulation frequency f and a duty cycle DC together with circuitry for adjusting the modulation frequency f and circuitry for adjusting the amplitude A and circuitry for adjusting the duty cycle DC.

Abstract: The device includes a circuit for generating signals indicative of a reference current which is variable in steps and, during successive time intervals defined by a clock-signal generator, decreases according to respective predetermined functions as the voltage detected across the lamp increases, these functions corresponding substantially to respective predefined constant values of the power supplied to the lamp, and a differential comparator circuit which compares the values of the reference current generated with the current detected in the lamp and generates an error signal in dependence on the difference between them. The error signal can be used to control the device for supplying the lamp.

Abstract: A circuit arrangement and a method suitable for operating a low-pressure mercury discharge lamp which includes circuitry for adjusting the average amplitude of the current provided to the lamp as well as circuitry for adjusting the modulation of the current provided to the lamp.

Abstract: A universal electronic ballast system (10) is provided for actuating at least one gas discharge lamp (1900) having any one of a plurality of predetermined wattage ratings. Electronic ballast system (10) includes a filter circuit coupled to an AC power mains (100, 110) for substantially suppressing spurious signals passing into or from the power source. The filter circuit is coupled to a regulated switching power supply circuit (14) which generates a regulated boost voltage and draws a substantially constant in phase sinusoidal load current from the power source supplied to a switching circuit (16) which generates a regulated pulsating current at a predetermined frequency. Responsive to the regulated pulsating current a high voltage is induced in the primary windings (1710 and 1680) of induction transformer (T3). The high voltage is coupled to gas discharge lamp (1900) by means of the magnetic coupling betwen primary winding (1730) and secondary winding (1765) of the output transformer (T2).

Abstract: A direct current power supply which incorporates an alternating current circuit segment so as to enable the use of a reactive component as an impedance limiting circuit element. The alternating current is produced by pulse width modulation regulation of raw direct current and DC to AC inversion. A feedback circuit is provided to regulate the pulse width modulation in accordance with the direct current output by the power supply so as to obtain a desired output current.

Abstract: A device for alternating the polarity of an illuminated DC fluorescent light bulb to eliminate cathodic degeneration while avoiding the visible effects of flicker to maintain a constant lighting effect.

Abstract: In a process for starting a high pressure gas discharge lamp (GDL) of a motor vehicle of a type for which an alternating voltage is developed from a direct voltage, the alternating voltage being fed to an ignition device to ignite the high pressure gas discharge lamp, a lamp voltage and/or a lamp current is measured, an actual value based on lamp current and/or lamp voltage is compared with a desired value and after ignition of the high pressure gas discharge lamp for a predetermined time span, or period, an additional power is added to an operational power of the high pressure gas discharge lamp by means of changes in the alternating voltage which, on the one hand, is limited by a maximum permissible lamp current and on the other hand is terminated at the end of the predetermined time span.

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 transitor or by means of a time delayed starting pulse.

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 device for alternating the polarity of a regulated DC power signal applied to a fluorescent light system, which device selectively reverses the polarity of a DC power signal applied to a fluorescent lamp each time the light system is turned on and an AC power signal is applied. The device selects the polarity of the DC power signal applied to the lamp such that both terminals of the lamp act as a cathode approximately an equal number of times, thus preventing premature aging and degradation of any one lamp terminal.

Abstract: In electronic ballast having inverter rectifiers for fluorescent lamps, a regulation of the lamp current or of the lamp power is usually used in order to stabilize the lighting current independently of tolerances of the electrical properties of the fluorescent lamp or their aging phenomena. When such a regulation is simultaneously utilized for dimming the fluorescent lamp, difficulties arise at the lower limit of the dimming range at, for example, 1% of the nominal light power. The range of brightness at the lower limit is regulated on the basis of an additional regulation, dependent on the discharge resistance of the fluorescent lamp. An auxiliary measured quantity resulting therefrom is superimposed on the actuating quantity of the regulator that results from a reference/actual value comparison of the current or power regulation for the purpose of stabilizing the lamp current.

Abstract: A power supply for high voltage, low current gas discharge tubes such as neon, argon, and mercury vapor. 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: An improved self-regulating, no load protected electronic ballast system (10) is coupled to a power source (12) for actuating at least one gas discharge tube (b 66) with a regulated current and limited voltage to maintain the gas discharge tube (66) input and output power at a predetermined value. The improved ballast system (10) includes a filter circuit (11) coupled through a rectification circuit (16) to the power source (12) to provide a filtered output (28). The output line (28) is coupled to a first toroidal transformer winding (58) of self-regulating circuit (17) for monitoring the regulated current coupled to induction circuit (15). The induction circuit (15) includes a primary winding (42) tapped to provide an autotransformer configuration for establishing the magnitude of the regulated current.

Abstract: A ballast for starting and operating a high intensity discharge (HID) lamp in a dc mode includes an oscillator coupled to first and second direct current input terminals. The oscillator includes a high frequency generator driving a pair of semiconductor switches. A first transformer having primary and secondary windings is coupled to the semiconductor switches. A rectifier and voltage multiplier circuit converts the voltage across the secondary winding of the first transformer to a dc voltage. A first energy storage circuit coupled to the rectifier and voltage multiplier circuit stores energy for generating a negative-going, high-voltage spike sufficient for initiating a glow condition in the lamp. A second energy storage circuit, which stores energy for application to the HID lamp during starting, insures proper glow-to-arc transition.

Abstract: A circuit for starting and operating a high intensity discharge (HID)lamp in a dc mode includes a pulse width modulator (PWM) coupled to first and second direct current input terminals. The PWM includes a high frequency generator driving a pair of semiconductor switches. A first transformer having primary and secondary windings is coupled to the semiconductor switches. A rectifier and voltage multiplier circuit converts the voltage across the secondary winding of the first transformer to a direct current voltage. A first energy storage circuit coupled to the rectifier and voltage multiplier circuit stores energy for generating a high voltage spike which initiates a glow condition in the lamp. A secondary energy storage circuit, which stores energy for application to the HID lamp during starting, insures proper glow-to-arc transition.

Abstract: A device for use as an electronic generator for generating a highly realistic flickering light is disclosed which has adjustable brightness, flicker rate, and flicker level to accurately simulate a variety of lighting effects such as fire, reflections from natural sources, and light from man-made sources. The device uses a pseudorandom output generator to generate a variable level analog signal which may be adjusted in frequency, with additional controls being added to control the level of the signal of the signal variation and the overall signal level. The resulting signal is then used to drive lamps through relays, with multiple channels being used in the preferred embodiment.

Abstract: A ballast circuit for a gaseous discharge lamp, particularly a neon light, includes a diode bridge rectifier for producing a d-c voltage from an a-c input and a transformer with a secondary winding connected to the lamp and a primary winding connected to the rectifier. A switching circuit is connected to the transformer primary winding for controlling a flow of current therethrough from the rectifier. The switching circuit includes at least one MOSFET having a drain terminal connected to the transformer primary winding and a grounded source terminal. A control circuit is connected to a gate terminal of the MOSFET for controlling the on and off times thereof, the control circuit including a pulse generator for producing a train of pulse-width-modulated rectangular pulses of substantially a single frequency fed to the MOSFET's gate terminal.

Abstract: An electronic switching ballast for fluorescent lamp having a rectifying circuit, a square generator, a phase discriminator, a switching time differentiating circuit and a wave shaping circuit. The alternating current input signal provided to the ballast is rectified by the rectifying circuit to a direct current signal. The square generator generates a square wave signal in reference to the direct current signal. The phase discriminator compares a feedback signal from the wave shaping circuit with a reference signal corresponding to the direct current signal to provide a full-wave rectified signal. The switching time differentiating circuit combines the square wave signal and full-wave rectified signal, and differentiates the combined signal to generate a pair of pulsed signals. The pulsed signals are out of phase with respect to one another.

Abstract: To reduce network harmonics upon connecting a fluorescent lamp (LP) with a ower network rectifier (2) and a push-pull frequency generator (3) and a series resonance circuit (4) to the network, a harmonic filter is connected in the circuit with the fluorescent lamp. The harmonic filter includes two diode pairs (D8, D9; D10, D11) connected in forward current passing direction to the power rectifier (2).

Abstract: A high efficiency, electronic ballast is taught for high pressure sodium (HPS) lamps. The ballast is powered by AC line current which is rectified so that 160 volts of direct current lights the lamp. The ballast maintains constant wattage to the lamp and constant line wattage. A striker circuit develops a high voltage, short duration pulse to strike the lamp.

Abstract: A synchronized ballast for a discharge lamp having an increased dimming range. The ballast includes semiconductor switches coupled to a generator to receive a high frequency signal. A variable pulse width modulator includes a one-shot multivibrator for generating a pulsed signal for interrupting conduction of the semiconductor switches and thereby controlling the intensity of the discharge lamp. A delay means is electrically coupled to the variable pulse width modulator for delaying the generation of the interrupting pulsed signal whereby the voltage across the discharge lamp is zero for a predetermined amount of time after power is applied to the ballast and prior to lamp starting. The ballast may further include a power factor correcting means in the form of an inductor shunting the secondary winding of an arc transformer.

Abstract: A chopper circuit is series connected between a conventional ballast and the fluorescent lamps to provide a high frequency current to the lamps to increase and adjust the luminance thereof. The chopper circuit comprises a diode bridge with a transistor connected across the DC terminals thereof. The lamps are series connected with the AC terminals. A photocell is used in a feedback circuit to maintain constant lighting.

Abstract: The ignitor is a high voltage power supply for intermittent operation used to ignite HMI (Hydrargyrum Medium Arc Iodide), Xenon and mercury arc lamps of the type typically used in motion pictures, video applications, theater and television. The ignitor inputs through a rectifier circuit and the rectified current drives the primary coil of the first transformer of two ganged transformers. The primary coil is driven into saturation, at which point a pulse-width modulated controller senses that the saturation current has been reached in the primary, and opens a FET which acts as a switch in series with the primary, collapsing the field around the primary to induce an energy surge into the secondary, which results, after further conditioning and transforming, in the production of a high voltage (30 kv-50 kv) arc-jumping current to ignite the arc lamp to which it is connected.

Abstract: A control system for lighting a bank of fluorescent lamps, includes input terminals (10, 11) for a mains voltage (e.g. 240 v) and output terminals (20, 21) to which the bank of lamps is connected. A transformer (T1) provides a reduced voltage (216 v) as compared to the mains supply voltage. The transformer (T2) provides a supplementary voltage (24 v). Upon start up of the circuit, a control circuit (CC) operates contact (A1) to energize the transformer (T2) so that terminals (20, 21) receive both the reduced voltage from (T1) and the supplementary voltage from (T2) (i.e. 240 v) which is sufficient to ignite the fluorescent lamps. The control circuit (CC), after a predetermined delay (e.g., 15 seconds), switches contact (A1) to disconnect the supplementary voltage from (T2). The lamps then continue to operate on the reduced voltage (216 v) thereby reducing the power consumed by the lamps.

Abstract: Apparatus for use with a fluorescent light dimming circuit to delay the application of power to the lamp for a first time period sufficient to allow the electronic components to stabilize and thereafter to delay any dimming signal to the lamp and, instead, apply full power to the lamp for a time period sufficient to allow the filament of the lamp to warm up.

Abstract: A high leakage reactance transformer especially for current limited control of gas discharge lamps and other electrical discharge loads has a core with three legs defining two magnetic loops. A first leg has an air gap with a fixed reluctance, a second leg is common to both loops and has a primary winding, and the third leg has a supply winding for connection to the discharge device as well as a control winding connected to a control circuit. The control winding has an adjustable load to vary the reluctance of the third leg and control the current limit of the supply winding. Linear and proportional control circuits are shown.

Abstract: An electronic control system employing logical control for controlling a gas vapor arc globe. Power from a power source such as an AC power line or DC or AC generator is connected by a control switch to a logical control circuit which initially activates the igniter for the globe. In the event that the igniter does not cause the globe to ignite a control signal is provided to turn the power off. The voltage for operating the globe is boosted by means of a boost voltage generator to a substantially higher voltage than that of the power source. The operating voltage for the globe is generated by means of a multivibrator which runs at a relatively low frequency and a pulse width modulator which runs at a high audio frequency. The square wave output of the multivibrator (typically 60 Hz) is modulated by the pulse output of the pulse width modulator (typically 20 KHz) to provide a square wave DC to the globe modulated by high frequency rectangular pulses having a width which determines the intensity of the globe.

Abstract: The present invention relates to an improved line regulated ballast circuit for use in controlling varied lighting applications such as, for example, neon signs and fluorescent tubes. The inventive circuit, when used in neon lighting applications, may include a function generator which controls the lighting of the neon tube in a manner allowing the tube to slowly write from one end to the other in alternating current. The function generator also allows such functions as flashing, modulation, steady state operation and steady state operation with dimming function. In a further aspect, the inventive circuit with transformers connected in parallel with one another, may be utilized to simultaneously control a plurality of neon tubes, fluorescent tubes, or both concurerntly. In this application, each of the transformers may be provided with a shunting mechanism designed to render the output current thereof infinitely adjustable.

Abstract: In a fluorescent lamp, a "soft" start-up circuit initially applies a lamp, or inter-electrode, voltage which is limited to a peak voltage that will not start the lamp prior to heating of the lamp cathode to the proper temperature. The lamp cathode is then heated to the proper start-up temperature after which the lamp voltage is increased to a value well in excess of the ignition voltage required for all lamp types and operating characteristics in initiating lamp operation. The increased lamp voltage is applied in a pulsed manner until the lamp is ignited, whereupon the lamp may be operated at normal lamp current and cathode voltages or the lamp filaments may even be turned off with a consequent savings in input power.

Abstract: An improved dimmer apparatus which can protect an output power transistor for a lamp of a load when the lamp is short-circuited and which can eliminate manual operation for restarting the apparatus after recovery of the short-circuiting of the lamp. The apparatus comprises a detecting circuit which detects short-circuiting of the lamp to turn the transistor off. After lapse of a predetermined interval of time given by a timer circuit, the transistor is turned on to detect whether or not the lamp is still short-circuited. If the lamp is still short-circuited, the transistor is again turned off and then a same sequence of operations will be repeated until it is detected that the short-circuiting of the lamp has been recovered and thus a normal operation of the apparatus is restarted.

Abstract: A starting, hot restarting and operating circuit includes a pulse circuit for applying high voltage pulses to an HID lamp for starting or hot restarting. After a set interval of pulses if the lamp has not ignited, the pulse circuit is turned off for a selected inactive interval after which pulses are applied to the lamp again. If ignition does not occur after several active/inactive cycles, the circuit is deactivated until reset by turning the power off and on.