Abstract: In a switching inverter where transistor switches are controlled so as to provide current through an inductor which is connected in series with the switches across a battery so as to power a capacitive load (such as an electroluminescent lamp) with higher voltage than the battery voltage, control current for the switches and particularly the emitter to base current therethrough is shared by connecting the bases of these transistors via a current limiting resistor. Using the same base current reduces the battery drain and improves the efficiency (power applied to the load versus battery power drawn) of the inverter.

Abstract: The present invention features a gas discharge lamp electronic ballast that uses a frequency-dependent control circuit. The lamps are all energized by means of a single electronic ballast, including an electronically regulated power supply, a power oscillator/driver circuit, an output coupling circuit and a feedback circuit that provides frequency-to-voltage conversion for controlling the output voltage of the power supply. In this way, constant lamp current is maintained, regardless of the number of lamps connected. Since the remaining lamps are operated at their specified, correct lamp current, lamp life is preserved. Another feature of the circuit is its ability to dim the lamp output continuously over a limited range to reduce energy usable in circumstances in which full lamp illumination is not required. Such dimming can be controlled by a suitable external control signal such as from a potentiometer, switch, light monitoring device or a motion detector.

Abstract: In an electronic ballast, a half-bridge inverter is powered from a DC voltage and provides a nominal 30 kHz square-wave-like inverter output voltage. The inverter output voltage is applied to a series-resonant LC circuit. Parallel-connected across the tank capacitor of this LC circuit are plural series-combinations, each consisting of an instant-start fluorescent lamp series-connected with a current-limiting capacitor. The magnitude of the high-frequency voltage present across the tank capacitor is controlled by controlling the frequency of the inverter output voltage. Prior to lamp ignition, the magnitude of the high-frequency voltage is controlled to a relatively high level, such as to provide for sufficiently forceful lamp ignition. After the lamps have fully ignited, to enhance overall efficiency, the magnitude of the high-frequency voltage is reduced to a relatively low level. This low level is too low to provide for lamp ignition but sufficiently high to permit proper lamp operation.

Abstract: An inverter-type electronic ballast for a gas discharge lamp is powered by a DC supply voltage provided from a rectifier-filter combination connected with an ordinary electric utility power line. The absolute magnitude of the DC supply voltage is higher than the peak absolute magnitude of the power line voltage. The ballast includes an inverter circuit operative to provide an inverter output voltage of special trapezoidal-like waveshape; which output voltage is applied to a series-resonant combination of an inductor and a capacitor. The gas discharge lamp is connected in parallel with the capacitor. The inverter is driven by a voltage of special waveshape and controllable frequency. By controlling the frequency, the magnitude of the current supplied to the gas discharge lamp can be adjusted, thereby correspondingly adjusting the amount of light produced by the lamp.

Abstract: A control module controls the illumination intensity of a fluorescent lamp. A controller controls a switch to conduct current through cathodes of the lamp, and the switch ceases conducting current when commutated into non-conduction. The switch is triggered into conduction at a predetermined extinguishing point within and prior to the end of each half-cycle of applied AC current. The switch is thereafter commutated into non-conduction at a predetermined ignition point when the applied AC current reaches a predetermined level near the zero crossing point of each half-cycle of applied AC current. The current level at commutation creates a sufficiently high di/dt effect to cause an ignition pulse of voltage from the ballast across the lamp cathodes sufficient to ignite the ionized medium into an illumination plasma. The switch extinguishes the plasma. The illumination intensity of the lamp is related to the time between the ignition point and the extinguishing point.

Abstract: An EL lamp is driven by a flyback inverter having an inductor connected in series with a first transistor which switches on and off at a high frequency. The junction of the inductor and transistor is connected through a switching diode to an output terminal for connection to an EL lamp. A discharge path, including a second transistor, is coupled to the lamp for removing accumulated charge. The second transistor switches on and off at a low frequency for periodically discharging the electrical charge accumulated on the EL lamp. In accordance with one aspect of the invention, several diodes are connected in series with the switching diode to block waste current during discharge of the EL lamp. In accordance with another aspect of the invention, the switching diode is temporarily by-passed to provide the discharge path for the lamp. In accordance with either aspect of the invention, the inverter can produce alternating current through the lamp by adding a capacitor in series with the lamp.

Abstract: A power line-operated electronic converter is adapted to deliver a relatively constant magnitude high frequency signal to a load(112) and is operable to draw a substantially sinusoidal current from the AC voltage source (101). The converter has DC input terminals (B+,B-) having a capacitor (105) connected therebetween. First and second rectifier bridges (103,104) are coupled to the DC input terminals. A resonant oscillator circuit (108) is coupled to the DC input terminals and to the transistor inverter employing a resonant inductor (111) and a resonant capacitor (110). An input-output feedback is implemented by coupling of a voltage developed across the resonant inductor to a differential voltage proportional to a difference of a voltage developed across DC input terminals and a voltage provided by a rectified AC voltage source, and modulation of frequency of oscillation in proportion to the differential voltage.

Abstract: A discharge lamp lighting device has first switching means for converting AC power into DC power and second switching means for converting the DC power into a high frequency power, the first switching means being driven subsequently to a driving of the second switching means, and the device is arranged for intermittently applying a pulse voltage to a discharge lamp during its dimming lighting, whereby any secondary voltage can be effectively lowered and any flash apt to occur during the dimming lighting can be restrained.

Abstract: An electronic ballast has a high voltage portion and a low voltage portion. The high voltage portion includes a converter, having a variable frequency boost circuit, and a half-bridge, driven inverter having a series resonant, direct coupled output. The low voltage portion of the ballast includes a control circuit and fault detectors for shutting off the boost circuit and the inverter circuit. The fault detectors consume very little power when the ballast and lamp are functioning normally. Separate magnetics are used for boost, inverter, and output. Each magnetic is essentially cubic in shape and carries as little current as possible.

Abstract: Current supply means for a laser flash lamp contain a fast switch and control means which modulate the amplitude of each individual pulse with a presettable modulating frequency and depth of modulation. This permits higher peak envelope powers to be obtained at an unchanged mean power of the individual pulses so that the necessary threshold values can be better exceeded during materials processing. The amplitude modulation of the individual pulses also prevents undesirable shielding plasma from forming above the processing place.

Abstract: A power supply for driving one or more loads includes a DC voltage source, an inverter connected to the DC voltage source for providing a high frequency AC voltage at its output end, and an output transformer having a primary winding and a secondary winding. The primary winding is coupled to the output end of the inverter through a tuning inductor, while the secondary winding is coupled to the load. A tuning capacitor, which constitutes a resonant circuit in cooperation with the resonance inductance for supplying a resonance current to the load, is connected across the secondary winding of the output transformer in parallel relation to the load. The tuning capacitor is arranged in circuit on the opposite side of the secondary winding from the load such that the tuning capacitor is open-circuited when the load is disconnected from the secondary winding.

Abstract: An electronic ballast includes a boost circuit, a low voltage control circuit, and a driven inverter in a half-bridge, push-pull, series resonant, parallel loaded configuration. The boost circuit includes a low voltage output for powering the control circuit. In the event of a fault, the control circuit shuts off the boost circuit and the inverter. A sense capacitor is in series with the lamps and the voltage across the capacitor prevents a timer in the control circuit from shutting off the ballast. The timer circuit waits a period longer than the time it takes for the lamps to start normally. The sense capacitor is either in series with the lamp across the resonant capacitor or is in series with the resonant capacitor.

Abstract: A compact folded fluorescent lamp and a small incandescent lamp are both mounted on an ordinary Edison-type screw-base capable of being screwed into an ordinary lamp socket at which ordinary AC power line voltage is controllably provided. An inverter-type ballast is integrally combined with the base and is operable to power the fluorescent lamp whenever the base is indeed screwed into the lamp socket. The incandescent lamp is powered from the AC power line voltage by way of an SCR whose conduction angle is controlled such as to cause the total light provided from the combination fluorescent-incandescent lamp to remain substantially constant from the very first moment that AC power line voltage is provided at the lamp socket. Thus, when the AC power line voltage is initially provided, the light provided from the incandescent lamp will be at its maximum while the light provided from the fluorescent lamp will be at its minimum.

Abstract: A lighting device for a high-pressure discharge lamp includes an inverter circuit for converting a DC voltage into an AC voltage using a pair of switching elements. The switching elements have a switching frequency for starting the high-pressure discharge lamp that is higher than a resonance frequency of a series resonance circuit connected in parallel with the discharge lamp. However, in a lighted state of the discharge lamp, the switching frequency is lower than the resonance frequency of the resonance circuit and is within a frequency range where acoustic resonance does not occur. The lighted state of the high-pressure discharge lamp is maintained by a voltage across a capacitor in the series resonance circuit.

Abstract: A first half-bridge inverter is powered from an unfiltered full-wave-rectified ordinary 60 Hz electric utility power line voltage. This first inverter provides at a first inverter output, across which is series-connected a first tuned L-C circuit, a first squarewave voltage of fundamental frequency between about 30 and 33 kHz; which first squarewave voltage is magnitude-modulated at 120 Hz. The first tuned L-C circuit, which is series-resonant at about 30 kHz, is parallel-loaded by a full-wave high-frequency rectifier whose DC output is applied to substantially constant-magnitude DC voltage existing across a pair of energy-storing capacitors. At a constant 30 kHz inverter frequency, the waveshape of the current drawn from the power line is substantially that of a squarewave in phase with the power line voltage, thereby giving rise to a power factor of about 90%.

Abstract: A multi-resonant boost power factor correction circuit includes a full-wave rectifier; a high frequency filter capacitance coupled across the input terminals of the full-wave rectifier; a series half-bridge converter; a diode connected between the output of the rectifier and the dc bus voltage such that its cathode is connected to a dc bus; a capacitance coupled between the output of the rectifier and the junction between the series-connected switching devices of the half-bridge converter; a resonant load circuit connected to the junction between the switching devices, including a resonant inductor, a resonant capacitor and a load, such as a fluorescent discharge lamp; and a driver circuit for alternately switching the switching devices via a dead time control for selecting a dead time after one of the devices switches off and the other device switches on.

Abstract: A lamp system including an alternating current power source for supplying a signal voltage, an input transformer having primary and secondary windings connected to the power source for increasing signal voltage, a signal rectifier connected to the secondary winding for creating a direct current signal from the increased signal voltage, a signal oscillator connected to the signal rectifier for creating a high-frequency signal from the direct current signal, one or more ballasts connected to the signal oscillator to create high-voltage high-frequency signals from the direct current signal, one or more lamps driven by the high-voltage high-frequency signal from the ballasts, a sense winding on an output side of each of the ballasts for inducing alternating current signals, an apparatus for receiving and processing the alternating current signals, and an apparatus for displaying the processed alternating current signals.

Abstract: The electronic reactor for discharge lamps (L) comprises a bridge rectifier (5) connected to an alternating voltage source (3); a half-bridge with two controlled switching means (11, 13) made alternately conducting to connect the said lamp (L) and the said bridge rectifier (5); a resonant load circuit (17) connected to the said half-bridge (11, 13); and a smoothing capacitor (29) connected in parallel with the half-bridge (11, 13). An auxiliary resonant circuit (33) is provided to reduce the crest factor and correct the power factor between the output (19) of the half-bridge (11, 13) and the positive pole (5A) of the bridge rectifier (5).

Abstract: An inverter circuit produces a proper electric power to be supplied to a discharge lamp. A feedback control system detects a lamp voltage and a lamp current, or a lamp power of the discharge lamp, and feedback-controls the inverter circuit based on the detected at least one of the lamp voltage, lamp current and lamp power. A response switching circuit switches a response speed of the feedback control system so that the response speed is high in a low luminous efficiency region, and is low in a high luminous efficiency region.

Abstract: A ballast circuit for a gas discharge lamp, of the type having a pair of resistively heated cathodes that are resistively heated both during a cathode pre-heat period prior to lamp turn-on, and during steady state lamp operation, is disclosed. The ballast circuit includes circuitry for providing, on a bus conductor, a d.c. bus voltage with respect to a ground, and a converter, responsive to the d.c. bus voltage, for supplying bidirectional current to a resonant load circuit. The resonant load circuit includes the gas discharge lamp, a resonant capacitor coupled between the lamp cathodes such that its voltage varies with lamp voltage, and a resonant inductor serially coupled to the resonant capacitor and cooperating therewith to set a magnitude, and resonant frequency, of the bidirectional lamp current. Circuitry is provided for powering the resistively heated lamp cathodes, to thereby heat the cathodes.

Abstract: The invention is a source of illumination including a lighting tube requiring converted electrical energy in order to provide the illumination. First and second electrical connectors are provided for receiving low voltage DC energy. An energy convertor receives the low voltage DC energy from the first and second electrical connectors and converts it to the converted electrical energy. Electrical leads are coupled to the energy convertor and to the lighting tube for applying the converted electrical energy from the energy converter to the lighting tube. The first and second connectors are electrically coupled in parallel with each other for selectably applying the low voltage DC energy to the energy converter by way of either of the first and second converters. The lighting tube is a gas discharge tube and the first and second electrical connectors are disposed at opposite end regions of the lighting tube.

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: Controlled DC supply voltage is provided to a self-oscillating FET bridge inverter ballast from a pre-converter and by way of an inductor having two separate windings on a common magnetic core--with one winding being positioned in each leg of the DC supply. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the bridge inverter's output, thereby providing a special AC output voltage thereat. This special AC output voltage is characterized in that it exhibits an unusually high rate of voltage change at its cross-over points but otherwise has a substantially sinusoidal waveshape. An instant-start fluorescent lamp is connected via a current-limiting capacitor across the bridge inverter's output. The magnitude of the DC supply voltage is so chosen as to cause the magnitude of the AC output voltage to be such as to effectuate proper instant-starting of the fluorescent lamp. Because the AC output voltage is balanced with respect to ground, U.L.

Abstract: A restart circuit for a dc arc lamp, which is subject to power variations that cause the lamp to extinguish, includes a power circuit for supplying the dc arc lamp with current that has a constant current value while the lamp is operating. A current monitor connected to the power circuit monitors the current supplied to the dc arc lamp and provides a current sense signal corresponding to the supplied current. A comparator, which is connected to receive the current sense signal, provides a restart signal having a hysteresis characteristic. The restart signal is activated when the current sense signal falls a first predetermined value below the constant current value (indicating that the lamp has extinguished) and deactivated when the current sense signal rises above a second predetermined value greater than said first predetermined value, but still less than the constant current value.

Abstract: In an electronic ballast, a series-resonance-loaded half-bridge inverter is powered from a DC voltage and provides an AC voltage at an AC rail across which are connected plural lamp-ballast series-combinations, with each lamp-ballast series-combination consisting of a current-limiting capacitor series-connected with an instant-start fluorescent lamp. The DC voltage, which is obtained via a pre-converter, is controlled so as to maintain a predetermined magnitude even during the lamp ignition process. The 35 kHz AC voltage is generated by the half-bridge inverter powering a series-tuned L-C circuit near its natural resonance frequency. The AC rail is connected across the tank-capacitor of the L-C circuit. Except for being reduced so as to maintain total lamp current below a predetermined level on a sustained basis, the magnitude of the AC voltage is controlled to a given level in response to an AC control action applied to an AC control input.

Abstract: Briefly, to reduce switching stresses, employed is a high-frequency AC power source (110) and a current-limiting (ballasting) network (116). The network ( 116 ) includes a high-frequency trap ( 120 ) and an impedance transforming network (122), which is coupled to the AC power source (110) by the trap (120) and which is for connection to a load that includes at least one gaseous discharge (fluorescent) lamp or other non-linear or negative-resistance load (102). The trap, which has the parallel resonant combination of an inductor ( 130 ) and a capacitor ( 132 ), is resonant at a frequency chosen such that the switching-circuit transistor(s) (210, or 230 and 232, or 250 and 252, or 270 and 272, or 708) of the AC power source (110) switch at times when the level of the current (charge flowing) therein and/or the voltage developed there across is zero, preferably, at a frequency slightly higher than a harmonic frequency of the high-frequency AC power source ( 110 ).

Abstract: A control device and methods of making and operating the same are provided, the control device comprising a microcomputer unit, a vacuum fluorescent display unit having a filament unit, a power supply unit for being interconnected to a high voltage alternating current power supply that has a certain frequency, and a circuit operatively interconnecting the units together, the power supply unit comprising a transformerless capacitor arrangement for creating a low voltage direct current from the power source to power the microcomputer unit, the circuit comprising an oscillator unit that receives the direct current and pulses the same through the filament unit at a frequency that is greater than the certain frequency and that causes the filament unit to heat to an operating temperature thereof.

Abstract: A ballast includes an inverter for providing an AC voltage to a discharge lamp. As the lamp approaches end-of-life a DC voltage component develops across the lamp. The ballast includes circuitry for monitoring the condition of each of the cathodes by measuring this DC voltage component. After a predetermined increase in this DC voltage component, the inverter is disabled in order to prevent excessive heating of the cathodes.

Abstract: A novel dimming assembly for controlling light intensity of a gas discharge lamp, including:dimming controller having an input terminal connectable to one pole of an alternating current source and having an output terminal connectable to the line leading to one of the two filament electrodes of the lamp, the dimming controller being adapted to provide an attenuated and conditioned power at its output terminal;the dimming controller being adapted upon feeding the input terminal with the current, to operate in full power mode for a time period t.sub.1, during which the link between the two terminals is in full conductance bringing about full light intensity of the discharge lamp, and being further adapted after t.sub.1 to enter into a dimming mode, during which the link between the two terminals is in partial conductance bringing about attenuated intensity of the discharge lamp; the said time t.sub.1 is sufficient to facilitate effective dimming in the dimming mode.

Abstract: The resolution .DELTA.C of a binary capacitance ladder having a plurality of N branches is precisely determined by appropriately selecting the value of a fixed capacitor in each branch relative to the parasitic capacitance of a corresponding series-connected switch. The capacitance of each respective branch varies by 2.sup.n-1 .DELTA.C, where n is the number of the branch, adjacent branches being numbered sequentially. The total capacitance is variable between C.sub.Total and C.sub.Total -(2.sup.N -1).DELTA.C in steps of .DELTA.C, where C.sub.Total is the sum of the capacitances in the ladder with all switches closed, and C.sub.Total -(2.sup.N -1).DELTA.C is the capacitance of the ladder with all switches open. For any particular branch of the ladder, the switch capacitance may be further controlled by adding a fixed capacitance in parallel with the respective switch. Such a variable capacitance is useful as a tuning capacitor in an electrodeless HID lamp ballast.

Abstract: A circuit for providing AC power to an electroluminescent lamp powered by a battery comprises a high frequency oscillator through a control to drive a fly back voltage regulator comprising an inductor powered by a relatively low battery voltage and coupled to ground through a switching transistor. A capacitor coupled to the inductor through a diode is charged by the repetitive charge and discharge of the inductor when the transistor is switched ON and OFF at high frequency by the high frequency oscillator. The charge in the capacitor is dithered about a high DC voltage, such as 100 VDC, by sensing the charged voltage for periodically turning the transistor ON and OFF accordingly. A bridge circuit receives two pairs of like lower frequency square wave pulse signals of opposite polarity from a low frequency oscillator.

Abstract: An electronic supply for igniting and operating a high-pressure discharge lamp, comprising a first driven main switching device for generating a high-frequency current through an inductive element and a switching element suitable for subsequently supplying current through the inductive element when the first main switching device is non-conducting. The electronic supply is provided with a transformerless level shifter (LS) and with a driver circuit (S) comprising at least a switch drive device for driving the first driven main switching device. The switching element suitable for the subsequent current supply forms a part of a second driven main switching device which provides periodic commutation of the current through the inductive element, while the level shifter is free from any self-induction elements.

Abstract: A circuit arrangement for operating a discharge lamp, comprising a DC-AC converter provided with a branch comprising a series circuit of two switching elements, each switching element being shunted by a unidirectional element, while ends of the branch are provided with connection terminals suitable for connection to poles of a DC voltage source, a load branch comprising inductive means and lamp connection connection terminals suitable for accommodating a lamp, which load branch shunts one of the switching elements of branch. A first drive circuit I for generating a first drive signal during stationary lamp operation for rendering each of the switching elements in the branch alternately conducting and non-conducting, whereby each switching element is rendered conducting and non-conducting once in succession within a time interval during which the other switching element is non-conducting.

Abstract: An electronic ballast includes a triggered boost circuit, a driven inverter, and a low voltage signal generator in a a half-bridge, push-pull, series resonant, parallel loaded configuration. The boost circuit is triggered by a voltage from the inverter and the inverter is controlled by the low voltage signal generator. The boost circuit includes a low voltage output for powering the signal generator. In the event of a fault, the operation of the signal generator is interrupted, thereby shutting off the boost circuit and the inverter. A DC blocking capacitor is in series with the lamps and a resistor is connected in parallel with the DC blocking capacitor. The ballast is started by a pulse of displacement current through the lamp filaments to the boost circuit. Since the lamp filaments must be intact, the ballast does not begin a lamp starting sequence until lamps are connected to the ballast.

Abstract: To operate a low-pressure discharge lamp, typically a fluorescent lamp, from a low voltage source of, for example, between 5 and 24 V, two diodes (D1, D2) polarized to provide for current passage towards the lamp are connected between the output of a blocking oscillator and the lamp (L). At least one diode (D2) provides for preheating the lamp electrode. The other diode (D1) prevents immediate starting of the lamp; it is integrated in the circuit between the secondary winding (N2) of the blocking oscillator transformer (TR) and one lamp electrode (E1). The first diode (D2) is connected between the primary winding (N1) and the other terminal of the secondary winding (N2), and also to the other lamp electrode (E2). An additional capacitor (C4) connected, effectively, across the lamp (L) improves the starting of the lamp. The circuit is readily adaptable for association with a recharging circuit (FIG. 3) for recharging a rechargeable battery to supply the lamp.

Abstract: An electro-luminescent seasonal light apparatus includes a pig-tail plug mated with one pig-tail socket which extends from a regular seasonal Christmas/Halloween light string and provides a first AC power having a first voltage and a first frequency, an extension wire electrically connected to the pig-tail plug, a circuit box electrically connected to the extension wire for converting the first AC power to a second AC power which has a second voltage and a second frequency, an electro-luminescent component electrically connected to the circuit box for receiving the second AC power and flashing thereby, and a pattern shaper attached to the electro-luminescent component.

Abstract: A device for protecting a ballast circuit from excess voltage and excess current includes a switch for disconnecting the ballast circuit from the power source and a control circuit for operating this switch; the control circuit monitoring a control point, from which control point a first resistor connects to a first terminal of the power source, a second resistor connects to a second terminal of the power source, and a third resistor connects to a point between the switch and the ballast, the switch being brought into off-state when the voltage between the control point and the first terminal of the power source exceeds a given value, thus leading to a hysteresis between an input voltage for switching the device off and an input voltage for switching the device back on again, with positive feedback being provided by the third resistor for decreasing the switch-off time and the corresponding switching losses.

Abstract: A lighting fixture has a lamp and a housing for a lamp ballast. In the new fixture for providing bilevel illumination, the housing also contains a control device comprised of a dual capacitor and a "random crossing" relay connected to the capacitor. A single electrical control wire is attached to the relay and extends from the housing to a control module for remotely controlling the level of illumination consumed by the fixture. In a system employing one or more of the new fixtures, the level of illumination provided by each fixture is controlled by applying a signal to the control wire and switching the relay independently of the instantaneous value of the voltage across the relay terminals. A new method for providing two levels of power to the fixtures (and, thus, two levels of illumination) is also disclosed.

Abstract: A power supply with an inverter capable of avoiding the inverter from producing excessive high voltage when a load is detached or the load impedance is greatly increased. The inverter is energized by a fixed DC voltage source and includes at least one switching element and an L-C resonant circuit. The switching element is driven to turn on and off and cooperative with the L-C resonant circuit to produce a high frequency AC voltage at an inverter output for driving a load. The inverter includes first and second clamping diodes connected in series across the DC voltage source in anti-parallel relation thereto with the first and second diodes defining therebetween a first connection point. Also included in the inverter is a pair of first and second impedance elements which are connected in series across the inverter output to provide a divided voltage indicative of an output voltage of the inverter with the first and second impedance elements defining therebetween a second connection point.

Abstract: In an electronic ballast, a half-bridge inverter is powered from a DC voltage and provides an AC output voltage having a waveform with trapezoidally shaped half-cycles. The DC voltage is obtained by way of a pre-converter with a control input operative to permit control of the magnitude of the DC voltage. The AC voltage is applied across the primary winding of a leakage transformer, whose loosely coupled secondary winding is connected across a gas discharge lamp. The internal inductive reactance of the secondary winding constitutes a lamp ballasting means by way of limiting the magnitude of the resulting lamp current to a desired level. Prior to the flow of lamp current, the magnitude of the DC voltage is controlled by negative feedback to the control input so as to remain at a maximum level. After lamp current has started to flow, by negative feedback derived from the lamp current itself, the magnitude of the DC voltage is reduced so as to bring the magnitude of the lamp current down to the desired level.

Abstract: A power-line-operated half-bridge inverter is powered from a constant DC voltage and provides an AC output voltage that is--in contrast with the usual squarewave voltage--describable as being a sinusoidal waveform with the tops clipped off at some fixed magnitude; or, described differently, a waveform composed of truncated sinusoidal waves; or, described still differently, a waveform having trapezoidally shaped half-cycles. The DC voltage is derived via voltage-doubling from the power line voltage. The AC voltage is applied across the primary winding of a so-called reactance transformer, whose loosely coupled secondary winding is connected across a gas discharge lamp. The internal inductive reactance of the secondary winding constitutes a lamp ballasting means by way of limiting the magnitude of the resulting lamp current to a pre-established desired level.

Abstract: An apparatus for operating discharge lamps with a stable electric current supply and minimal dimensional area requirements. The apparatus includes an input power source coupled across a capacitor, establishing a first loop circuit. A discharge lamp may also be connected across the capacitor, thereby forming a second loop circuit. A first switch repeatedly turns ON and OFF, making and breaking the first loop circuit at a first frequency, and thereby charges the capacitor. A second switch repeatedly turns ON and OFF, making and breaking the second loop circuit at a second frequency, and thereby discharges the capacitor through the discharge lamp. A control mechanism controls the first and second switches for supplying a predetermined current to the discharge lamp for flickerless operation.

Abstract: A gas discharge image display is formed by disposing a plurality of fluorescent lamps 1 each comprising a glass bulb 2 within which a rare gas is sealed, one or more pairs of external electrodes 5a and 5b located on the outer wall of the glass bulb 2, and a fluorescent layer 3 formed on the inner wall of the container facing the external electrodes 5a and 5b. An alternating voltage pulse is applied between the paired external electrodes 5a and 5b by an X drive circuit 9 and a Y drive circuit 10 for discharge light emission, thereby displaying an image. The pressure and alternating voltage in the fluorescent lamp 1 are changed in response to the type of fluorescent material, thereby making near light emission and discharge characteristics of the discharge lamps which differ in electric characteristics.

Abstract: The present invention relates to an inverter driven lamp arrangement. The arrangement provides for the sensing of both lamp voltage and current. The arrangement also provides for a large current during times of low voltage and a small current during times of high voltage. The sensing of lamp current is done by a current detector that is connected to a resonance circuit whose output is applied in signal form to a lamp start control circuit. The resonant circuit is a series connected resonant circuit composed of a choke coil and a first capacitor. This series connected arrangement is further connected in series with a second non-resonant capacitor. Also the arrangement includes circuitry to gradually reduce the frequency of the inverter just after the lamp starts.

Abstract: Power factor is increased and harmonic distortion is decreased in a boost circuit by varying the current drawn in phase with the ripple voltage from a rectifying bridge. The boost circuit includes a series connected inductor and switching transistor and the control electrode of the switching transistor is connected to a second inductor. The second inductor is magnetically coupled to the first inductor and provides feedback for sustaining high frequency oscillations in the boost circuit. A third inductor is magnetically coupled to the first and second inductors and to the control electrode of the switching transistor. The voltage from the third inductor is rectified and filtered to remove the high frequency pulses but not the ripple and the voltage is coupled to the control electrode of the switching transistor for changing the power consumed by said boost circuit in phase with the ripple.

Abstract: A power-line-operated inverter-type ballast powers one or more fluorescent lamps in a lighting fixture. The ballast comprises self-oscillating inverter means wherein the frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals connected in circuit with the inverter's positive feedback circuit. The ballast also comprises optical sensor means so positioned and constituted as to sense the light level within the lighting fixture and to provide a control signal commensurate with that light level. This control signal is then applied to the control terminals in such manner as to regulate the inverter frequency as a function of the light level, thereby correspondingly to regulate the magnitude of the current fed to the fluorescent lamps.

Abstract: To prevent bowing of the arc of a high-pressure discharge lamp operated horizontally, the lamp is supplied with alternating current of between 10 kHz and 100 kHz, in which the frequency and wave shape of the alternating current portions of the supply are so selected that standing radial acoustic resonances will be formed within the discharge medium or fill in the discharge vessel, which standing radially directed acoustic resonances suppress or counteract bending of the discharge arc due to convection phenomena.

Abstract: Circuitry is disclosed for operating with no stroboscopic effects at least three fluorescent lamps connected to a single source of single phase alternating voltage. In order to suppress the stroboscopic effects, the first lamp circuit (1) is connected in the usual way to both conductors (S;Mp) of the source of single phase alternating voltage; a series oscillating circuit (4) composed of an inductive resistor (L) and a capacitor(C) is arranged in parallel to the first lamp circuit; the second lamp circuit (2) is connected between a conductor (S) of the source of single phase alternating voltage the point of connection (Vp) between the inductive resistor (L) and the capacitor of the series oscillating circuit (4); and the third lamp circuit (3) is connected between said point of connection (Vp) and the other conductor (Mp) of the source of single phase voltage.

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).