Abstract: The present invention relates to a method and apparatus for driving discharged lamps and which is adapted to maximize the luminous efficiency of a discharged lamp and its associated electronic driving apparatus. This is accomplished through the power sourcing characteristics of the driver, by causing the required power to dissipated while maintaining the power factor in the lamp as near unity as possible with the real components available for the implementation of the apparatus.

Abstract: Appliances such as fluorescent lamps and low-voltage DC motors can be operated from household AC without a transformer by employing a current-limiting circuit which is compact, lightweight, reliable, draws less energy, and has fewer power consuming components than do prior devices for driving those applicances. The current-limiting circuit has 4 rectifiers in a bridge circuit and a current-limiting capacitor which should be selected to match the load, a larger capacitor being necessary to supply a larger current. When used to drive a discharge lamp, the current-limiting circuit should also contain an inductive coil in series with the current-limiting capacitor. Otherwise there may be undue flicker. The inductive coil and capacitor together improve the power factor and therefore reduce the current drawn from the line without reducing the lamp output.

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 in synchronism 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 by way of the timing of the switching action of the inverter.Hence, in contrast with the ordinary situation where an inverter is supplied with net power from its source of DC voltage and where this net power is then supplied to a load connected with the inverter's output, the present invention relates to a situation where no net power is supplied to the inverter from its source of DC voltage and where no net power is supplied from the inverter's output.

Abstract: A discrete device in which a capacitive and inductive function has been integrated is comprised of at least two insulated amorphous ribbons which are spirally wound to form a cylindrical toroid. Each of the amorphous metal ribbons is insulated from each other ribbon by a dielectric layer and wound in a stacked configuration to provide the capacitive function. Two conductive windings are then wrapped around segments of the cylindrical toroid to provide inductive and/or transforming functions as desired. A magnetic circuit is formed through the windings by the amorphous metal ribbons. A dielectric insulating layer between the ribbons is offset from the longitudinal edge of the ribbon so that the longitudinal edge of each ribbon is exposed. One ribbon has its longitudinal edge exposed on one surface of the toroid while another ribbon has its longitudinal edge exposed on the opposing surface of the toroid.

Abstract: A discharge lamp driving circuit includes a chopper with a first switching circuit and an inverter with a second switching circuit. The chopper and inverter are connected to a dc voltage source and controlled to produce a composite lamp driving current composed of a high frequency alternating current interrupted by a dc current in order to keep the discharge lamp free from an acoustic resonance. The chopper and the inverter are arranged to have at least one common switching element in their first and second switching circuits.

Abstract: An apparatus for starting and operating an arc lamp used in health care applications includes means for producing a rectangular wave AC signal with a frequency controlled by external resistive and capacitive networks. Parallel-connected inductor and capacitor means form a resonant circuit to receive the rectangular wave AC signal. Additional capacitor means connected in series with the arc lamp is closed into the circuit when the arc lamp begins to conduct, thereby changing the resonant frequency of the parallel inductor-capacitor resonant circuit. The detection of current flow in the arc lamp causes a resistor to be switched into the resistive network controlling the frequency of the pulse-width modulated signal, thereby changing the frequency of the rectangular wave AC signal.

Abstract: A lamp start, hot-restart and operating circuit for a high wattage, high intensity discharge lamp includes cascaded resonant circuits with capacitors and series-connected inductors connected to an AC source. A pulse circuit including two pulse transformers supplies streamer-forming current, the secondary windings of the pulse transformers being connected in series with the lamp. When the lamp commences normal operation, the operating current energizes a relay to remove the capacitors and pulse circuit from the operating circuit, allowing the inductor to function as the lamp ballast.

Abstract: Subject invention relates to a fluorescent lamp ballast that is intended for safe and cost-effective use in lighting systems wherein the power to the various lighting fixtures is provided from a central source of relatively high frequency (Ex: 30 kHz) AC voltage. The ballast consists of a resonant series-circuit of an inductor and a capacitor--with the fluorescent lamp connected in parallel with the capacitor. Due to series-resonant action, if the lamp should happen to be non-connected or non-functional, and if proper precautions are not taken, the magnitude of the voltage developed across the capacitor may become so large as to cause damage to the circuit components and/or even to the source. To prevent such circuit damage, yet providing for a lamp starting voltage of suitably large magnitude and for an adequately long time, a Varistor voltage-limiting means is connected in parallel with the capacitor and a thermally actuated circuit breaker is connected in thermal contact with the Varistor.

Abstract: A circuit arrangement for operating at least one gas discharge lamp (5) with a periodically varying lamp current and adapted for connection to an alternating voltage source with a period N. The circuit is provided with a controlled semiconductor switch (3) and a control circuit for switching the controlled semiconductor switch with a switching period S in dependence upon a comparison between an actual signal proportional to the lamp current and a nominal signal derived from a voltage across the switching transistor (3).

Abstract: A low voltage electronic starter for an L-C Ballast of a fluorescent lamp is provided having a switching circuit having a resistive-capacitive network, a diac and triac, a transformer and a voltage multiplying rectifier.

Abstract: The present invention comprises a switching circuit which converts direct current electric power into a pulse; an insulative transformer which includes a primary coil for loading a generated pulse, coils for direct and alternating current outputs which are provided on the secondary coil side of the insulative transformer; an impendance circuit for controlling current which is connected with the coil for alternating the output; a control circuit which controls the switching circuit so that the output voltage of the coil for the direct current output is kept constant; and a fluorescent lamp connected with the coil for alternating the current output. The circuit can obtain the alternating current without secondary switching.

Abstract: An improved ballast (10) that operates an ionic conduction lamp (40) such as a conventional phosphor coated fluorescent lamp. The ballast (10) comprises an ac/dc converter that converts an a-c power signal to a d-c power signal that drives a transistor tuned-collector oscillator (30). The oscillator is comprised of a high-frequency wave-shape generator (32) that in combination with a resonant tank circuit (36) produces a high-frequency signal that is equivalent to the resonant ionic frequency of the phosphor. When the lamp (40) is subjected to the high frequency, the phosphor is excited which causes a molecular movement that allows the lamp (40) to fluoresce and emit a fluorescent light. By using this lighting technique, the hot cathode of the lamp, which normally produces a thermionic emission, is used only as a frequency radiator. Therefore, if the cathode were to open, it would have no effect on the operation of the lamp. Thus, the useful life of the lamp is greatly increased.

Abstract: In an inverter-type fluorescent lamp ballast, the inverter is powered from an ordinary electric utility power line by way of a rectifier means providing to the inverter a DC voltage having magnitude variations of about plus/minus 30% occurring at twice the frequency of the power line voltage. The inverter's output is a squarewave voltage of frequency averaging about 30 kHz and with amplitude modulations of about plus/minus 30%; which squarewave voltage is applied to a series-tuned L-C circuit. The fluorescent lamp is connected in parallel with the tank capacitor of this L-C circuit, thereby being provided with a current of magnitude proportional to the magnitude of the squarewave voltage. Within a significant range, the magnitude of the lamp current is a sensitive function of the frequency of the squarewave voltage; which frequency is modulated in such a way as to compensate for the variations in lamp current that would otherwise result from the amplitude modulation on the squarewave voltage.

Abstract: A fluorescent lamp is mounted on an ordinary Edison-type screw-base; which screw-base contains a frequency-converting electronic ballast. The combined lamp-ballast-assembly is adapted to be used in an ordinary screw-in lamp socket powered from ordinary 120 Volt/60 Hz power line voltage. The frequency-converting ballast within the screw-base converts the 120 Volt/60 Hz power line voltage to a high-frequency (20-30 kHz) substantially sinusoidal current, which is then used for powering the compact fluorescent lamp.

Abstract: In a self-oscillating inverter-type fluorescent lamp ballast, the inverter's output is a squarewave voltage of frequency controllable about 30 kHz. The squarewave voltage is applied across a series-connected high-Q L-C circuit. The fluorescent lamp is connected in parallel with the tank capacitor of this L-C circuit. Before the lamp ignites, the magnitude of the voltage developing across the tank capacitor is a sensitive function of the frequency of the squarewave voltage and is controlled to a suitable level by correspondingly controlling the frequency of the squarewave voltage to be higher than the natural resonance frequency of the unloaded L-C circuit. After the lamp has ignited, the magnitude of the lamp current is a sensitive function of the frequency of the squarewave voltage and is controlled to a suitable level by correspondingly controlling the frequency of the squarewave voltage.

Abstract: A lighting system, which includes one or more lighting apparatus sets, includes a control circuit. The control circuit has an ambient light sensing component and processing circuitry which produce a control signal whenever the intensity of ambient light reaches a given level and remains at that level or less. A delay (debounce) circuit receives the control signal and provides an output upon the expiration of a predetermined time interval which effects the transfer of power to the lighting apparatus set or sets and starts a timing circuit which is operatively arranged to assure continuing transfer of power to the set or sets for a given time interval, at the expiration of which power is removed from the set or sets. An alarm circuit also controlled by an output from the timing circuit may provide a warning alarm shortly before the expiration of the ON time interval. The control circuit may also turn OFF the power to the set or sets when ambient light of a set intensity becomes present.

Abstract: An apparatus for starting and operating a discharge lamp includes an inverter circuit. The inverter circuit comprises a parallel resonance circuit including an oscillation coil and capacitor, and which is connected to the discharge lamp, via a current-limiting coil, a switching transistor for triggering the parallel resonance circuit, and a feedback circuit connected to the switching transistor, for allowing a feedback signal for driving the switching transistor to be supplied to the base of the switching transistor, the feedback circuit being magnetically coupled to the current-limiting coil.

Abstract: A hybrid ballast apparatus for starting and operating a plurality of series-connected discharge lamps and which provides protection against electric shock. The ballast apparatus includes first and second bidirectional thyristors connected in parallel with first and second ones of said lamps, respectively, and a trigger control circuit for simultaneously triggering the thyristors into conduction. Each lamp has two filaments and means are provided for connecting an L-C ballast device, the lamp filaments and the first and second thyristors in a series circuit across the AC supply voltage terminals. If one end of a lamp is removed from its socket, the series circuit is opened so that the maximum voltage at any lamp electrodes is limited to the AC supply voltage.

Abstract: A high frequency system for gas discharge lamps includes a method of, and apparatus for, controlling the operation of a plurality of gas discharge lamps and provides; a reduction in starting and operating voltage and current; an increased range of dimming; and improved efficiency and reliability.

Abstract: Ballast and starting circuits for controlling current and voltage applied to an electrical dishcarge lamp. The ballast circuits use positive and negative capacitors which are alternately charged and discharged in an asychronous manner. The positively charged capacitors are charged during positive portions of alternating current and discharged during negative portions of the alternating current. The negatively charged capacitors are charged during negative portions of the alternating current and discharged during positive portions. Transistors or other appropriate switching means are used to switch the capacitors to the lamp during discharge thereof. Startup circuits are included for boosting the voltage applied to the lamp either manually or automatically upon startup. A startup regulator circuit is also shown for controlling current flow during periods of high current demand such as during startup.

Abstract: To reduce network harmonics upon connecting a fluorescent lamp (LP1) with a power 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 (LP1) or lamps (LP1, LP2). The harmonic filter includes two diodes (D8, D9), connected in forward current passing direction to the power rectifier (2), and two capacitors (C7, C8) connected, respectively, between the serially connected diodes and a center tap (M1) between the push-pull transistors directly and beyond an inductance forming part of a series resonance circuit (4) for the lamps. In parallel to the two diodes, two further diodes (D10, D11) are provided, having a center tap (M4) which is connected over a capacitor (C9) also to the center tap between the transistors of the push-pull frequency generator (3). Preferably, the capacity value of the further capacitor (C9) is about 0.

Abstract: There is disclosed a device and process for starting up a fluorescent discharge lamp in which a high-frequency pulse is generated having narrow voltage peaks above the voltage required to start electric discharge and broad valleys, applied to the elements of the lamp to effect start up of fluorescence and, after start-up, the voltage automatically goes back to maintenance voltage having broad peaks at the maintenance voltage and relatively narrow valleys. The automatic cutback is effected by the load introduced by the electric discharge and the feedback from the emitter of the transistor used to generate the pulse. A capacitor is serially-connected in the lamp circuit to inhibit the flow of DC current therein.

Abstract: A load side phase control circuit is used in conjunction with a conventional fluorescent light ballast (step-up autotransformer) and an isolation transformer to achieve fluorescent lamp brightness control. A resistor and capacitor connected in series shunt the phase control circuit to maintain low level illumination even when the phase control circuit is nonconducting and also provide a transient suppression when the phase control circuit switches to a conducting state. The circuit is especially suited to printed circuit board preassembly and subsequent connection to the lamp and ballast by a one step crimping operation. The resulting fluorescent lamp system--of the rapid start type--is well suited for use as a task light where the lamp is mounted relatively close to an underlying work area and receives power from a conventional outlet.

Abstract: To suppress introduction of harmonics into the power supply network of a high-frequency operated fluorescent lamp, an input capacitor (C2) connected across a direct current supply (P1, P2) for a transistor push-pull high-frequency circuit--operating at between 25-50 kHz--has a pair of serially connected diodes (D4, D5) connected thereto. The junction point (M2) of the diodes is connected via a coupling capacity (C7) to a common junction (M1) of the push-pull connected transistors (T1, T2). The power line circuit has a line choke (L2, L2') connected, either in advance or behind a rectifier (G1) supplying direct current to the transistor push-pull circuit. The circuit effectively suppresses harmonics, particularly the third harmonic, without introducing additional losses in the circuit, especially if a further capacitor (C8) is connected in the resonance circuit of the fluorescent lamp and to the diode junction (M2) between the two diodes (D4, D5).

Abstract: A high-intensity discharge (HID) metal vapor lamp and starting apparatus includes a metal vapor lamp having an outer envelope containing a gas filled arc tube, the fill gas including xenon, the arc tube having a pair of spaced electrodes with a starting aid surrounding the arc tube intermediate the electrodes, a non-linear dielectric element shunting the spaced electrodes and a ballast means and an electrical conductor coupling the spaced electrodes to a base member connected to a low voltage source whereby starting of the metal vapor lamp from a low voltage source is effected.

Abstract: To operate a fluorescent lamp having a lamp operating voltage of to about 0 V from a power supply having a nominal voltage level below lamp operating voltage, and without use of a voltage doubler circuit or a transformer to increase the power supply voltage, the power supply voltage is rectified, chopped, and then applied to the fluorescent lamp through a voltage increasing circuit which is formed as an LC resonance circuit. The inductive component can be formed by the current limiting choke, already present in a typical fluorescent lamp circuit, and the capacitative component by a small capacitor, for example of 6 nF value, connected to the choke to form a series resonance circuit.

Abstract: A low cost circuit addition in the form of a capacitor of suitable value provides effective starting and operation of rapid start, preheat, and instant start fluorescent type gas discharge lamps along with their standard A.C. operated ballast transformer auxiliary devices at reduced power levels to achieve energy conservation with a concomitant reduction in light output and can usefully employed in illuminated areas where a reduction in lighting level would not effect the utility of that particular area. The capacitor is connected in series with the ballast primary winding and is of such value as to cause ferro-resonance to occur in the ballast transformer primary circuit, thereby providing a voltage magnification effect to aid the lamp starting, or ignition, process i.e., during the time interval between circuit energization and production of a stable arc, and to thereafter operation of the lamp with reduced arc current.

Abstract: First and second capacitors are charged prior to a degaussing interval. A first switch couples the first capacitor to a degaussing coil to initiate the degaussing interval. The first capacitor and the degaussing coil form a resonant circuit that resonates to generate a decaying degaussing current. During a predetermined portion of each cycle of the degaussing current, a second switch couples a precharged second capacitor in parallel with the first capacitor to form a charge transfer arrangement that transfers charge from the second to the first capacitor for replenishing energy losses in the first capacitor. The charge transfer arrangement increases the duration of the time it takes to the amplitude of the degaussing current to decay and, hence, the length of the degaussing interval.

Abstract: A circuit supplied with direct voltage serves for generation of voltages and/or currents of differing curve shape and differing frequency and/or differing polarity. A load L with ohmic, inductive, capacitive or complex resistance behavior is switched in series with a choke D. Furthermore, at least two controlled semiconductor switches T.sub.1 and T.sub.2 are provided, which are each, respectively in series, as far as the load L and the choke D are connected, but which, however, lie in current paths 1 and 2 which are connected at different potentials of the supply voltage. In operational use, the one switch T.sub.2 is held open while the other switch T.sub.1 is opened and closed in alternating sequence, and after termination of an adjustable and controllable time period, the switch T.sub.1, which has been hitherto operated in alternating sequence, is now kept open, while the switch T.sub.

Abstract: A circuit for operating a discharge lamp (1) by means of a direct voltage. The circuit comprises direct voltage terminals (A,B) for connection of a direct voltage source, alternating voltage output terminals (K,L) for connection to the discharge lamp, a direct voltage/alternating voltage sine converter (3), and a current limiter (5) for limiting the current through the lamp in its operating condition. A controllable direct voltage converter (2) is coupled between the sine converter and the direct voltage input terminals.

Abstract: A light source including a spiral line pulse generator having an output coupled to one electrode of a high pressure discharge lamp and having an input for coupling to a source of lamp operating power for providing high voltage lamp starting pulses. This pulse generator includes, in addition to a spiral line generator, a solid state electronic switch in combination with an inductor. The electronic switch and inductor are connected in series between the conductors of the spiral line pulse generator for multiple discharge of the spiral line pulse generator to provide multiple high voltage pulses during each half cycle of lamp operating power to initiate discharge in the high pressure discharge lamp.

Abstract: An electronic ballast circuit for fluorescent or other gaseous discharge lamps includes a resonant half-bridge inverter circuit. The source voltage to the inverter is a full-wave rectified line voltage together with a DC carry-over voltage for supplying power in the inter-cusp period of the recitified line voltage. A negative feedback circuit is responsive to lamp current to vary the inverter drive frequency and thereby regulate lamp current. The frequency response of the feedback loop is high enough and the gain-versus-frequency response of the inverter is such that lamp current and voltage are regulated to reduce the crest factor of lamp current to compensate for variation in the amplitude of the voltage across the semi-conductor switches.

Abstract: A ballast circuit is provided for the start-up and operation of gaseous discharge lamps. A power transformer connected to an inductive/capacitive tank circuit drives the lamps from its secondary windings. An oscillator circuit generates a frequency modulated square wave output signal to vary the frequency of the power supplied to the tank circuit. A photodetector feedback circuit senses the light output of the lamps and regulates the frequency of the oscillator output signal. The feedback circuit also may provide input from a remote sensor or from an external computer controller. The feedback and oscillator circuits produce a high-frequency signal for lamp start-up and a lower, variable frequency signal for operating the lamps over a range of light intensity. The tank circuit is tuned to provide a sinusoidal signal to the lamps at its lowest operating frequency, which provides the greatest power to the lamps.

Abstract: A circuit arrangement for igniting and operating gas discharge lamps comprises a choke coil (1) connected between a lamp (2) and an a.c. supply source. The choke coil has an inductance L and an ignition device (3) is connected to the lamp. A capacitor (9) having a capacitance C is connected in parallel with at least a part of the choke coil in order to pass an ignition current to the lamp that is higher than the normal lamp operating current. The relationship betweeen the capacitive reactance of the capacitor and the inductive reactance of the choke coil is 1/.omega.C>3.omega.L.

Abstract: A multipulse starting aid for a high-intensity discharge lamp includes a spiral line, a bi-directional solid-state switch, or a spark gap, coupled to one of the ends of the spiral line, a resistance in association with the spiral line to provide an RC time constant. The time constant RC is so adjusted that, upon receiving the alternating current voltage from the appropriate source, a waveform of voltage is presented across the pair of terminals of the lamp, together with the series of pulses at the peak of each half cycle of the waveform. thereby enhancing the lamp startability.

Abstract: A circuit for operating low-pressure discharge lamps at elevated frequency comprises a reconnect circuit which disables the disconnect circuit upon exchange of a defective low-pressure discharge lamp (LP1). The disconnect circuit comprises a diode (D10), a resistor (R11) and a thyristor (TH) together with a trigger circuit (5). The reconnect circuit comprises a capacitor (C9) and a resistor (R12). Upon removal of the defective low-pressure discharge lamp (LP1), the capacitor (C9) is charged over the resistor (R12). Upon insertion of a new low-pressure discharge lamp (LP1), the capacitor (C9) is discharged and recharged in opposite direction and the holding current is removed from the thyristor (TH). This causes the thyristor (TH) to block, and enables the push-pull frequency generator (3) to start oscillating again.

Abstract: A current fed high frequency oscillator-inverter ballast circuit includes a parallel resonant tank circuit for driving a pair of series connected discharge lamps via a series ballast capacitor. A regenerative power supply switches on when a fluctuating main DC supply voltage drops below a given level thereby providing a constant level auxiliary DC supply voltage to the oscillator inverter to maintain oscillation and lamp operation. When the main DC supply voltage exceeds said given level, the regenerative power supply switches out. The oscillation frequency is f.sub.2 during operation of the main supply and automatically switches to a frequency f.sub.1 when the regenerative power supply takes over. The frequency shift is automatic during each half cycle of a 60 Hz AC supply and is in a direction so as to maintain lamp current relatively constant.

Abstract: A ballast adaptor circuit which makes it possible to convert a conventional two lamp rapid start T12 ballast for operation of two T8 fluorescent lamps and by means of a simple modification that does not require cutting wires or extensive rewiring of the T12 ballast device. The adaptor circuit comprises an auxiliary circuit including a tuned series-parallel LC network connected in parallel with either one or both of the lamps. The LC network is tuned to supply an odd harmonic current to the lamps, preferably the seventh harmonic. Improved starting is achieved by adding a series RC circuit and a SIDAC trigger device to the network to produce voltage pulses at the peaks of the AC supply voltage.

Abstract: A flourescent lamp lighting circuit comprising a rectifying circuit and an oscillatory circuit. The rectifying circuit comprises a rectifier bridge, capacitors and coils to rectify the local alternating power supply to direct power supply and provide rectified electrical power to the oscillatory circuit. The oscillatory circuit comprises two transistors and an L-C circuit which, taken together, form an astable circuit which generates and maintains oscillations. The frequency of the oscillations is determined by the nature of L-C circuits. The ON's and OFF's of the transistors are controlled by induction coils within which currents are induced by the variation of magnetic flux in the inductor coil of the L-C circuit. The high frequency oscillations in the oscillatory circuit induce high frequency electrical signals on a secondary coil which then lights the fluorescent lamp.

Abstract: Apparatus for igniting and operating a high pressure arc discharge lamp includes a pulse generating circuit for generating high voltage pulses for starting the lamp. The pulse generating circuit is comprised of a step-up transformer, a start capacitor, a voltage sensitive bidirectional switch (e.g., a sidac) and an impedance which forms a charge circuit for the capacitor. The capacitor discharges via the switch and a part of the transformer to generate a high voltage pulse which is coupled to the lamp electrodes. An auxiliary capacitor and a serially connected inductor are coupled in parallel with the pulse generating circuit so as to clamp the open circuit voltage at a high level upon generation of the ignition pulse thereby to maintain a level of lamp current sufficient to sustain the discharge arc. This makes the lamp ignition more reliable and extends the lamp life.

Abstract: Center-tapped DC power to a self-oscillating full-bridge inverter-type fluorescent lamp ballast is obtained from a regular power line by way of a voltage doubler. The DC power is supplied to the inverter through an inductor means having two separate windings on a common magnetic core--with one winding being positioned in each leg of the DC power supply. The full-bridge inverter, which comprises four switching transistors connected in usual full-bridge fashion, comprises a center-tapped parallel-tuned L-C circuit connected across its AC output, thereby providing a center-tapped sinusoidal voltage to its load, which consists of a fluorescent lamp connected in series with a current-limiting capacitor. Due to the effect of the inductor means, the current provided to the bridge is substantially constant during a complete period of the inverter's oscillation.

Abstract: A power supply circuit comprises a single discharge capacitor having a charging sufficient to trigger discharge in a discharge lamp. The discharge capacitor is associated with means for accumulating energy, with which it is charged. The energy accumulating means receives commercially available alternating current and applies the accumulated energy to the discharge capacitor to charge the latter. The power supply circuit may include an auxiliary capacitor which has a smaller capacitance and higher potential rating than the discharge capacitor. The auxiliary capacitor may have a potential rating sufficient to activate the discharge lamp alone. The discharge capacitor cooperates with the auxiliary capacitor to define discharge period. Preferably, the power supply circuit may include means for blocking or shutting off power supply at a given timing to precisely control the discharge period.

Abstract: A lighting apparatus which provides high voltage pulses for starting a high pressure sodium lamp. The apparatus includes two capacitors, two blocking diodes, a voltage sensitive symmetrical switch, and multiple resistances across which pulses are distributed. The aforementioned elements are electrically connected together and with a tapped ballast reactor so that one of the capacitors charges through an impedance in the negative half-cycle, and thereafter, when line voltage goes positive, the other capacitor charges through an impedance equal to the sum of the multiple resistances. When the voltage of the capacitors reaches a predetermined voltage exceeding the breakdown voltage of the voltage sensitive symmetrical switch, the capacitors discharge. This discharge, because of an autotransformer relationship within the reactor, produces a high voltage pulse of predetermined height and width once per each cycle of the source voltage.

Abstract: An electrical load controller includes a combination of switches for selecting a desired load output level, an electronic custom gate array for converting the switch signals to a parallel binary number, a parallel to serial data encoder for converting the multi-bit parallel data signal into a multi-bit serial data signal, a frequency shift key connected to a resonant circuit generating a controllable high frequency signal and for shifting the high frequency either up or down from the center frequency coupled to a power line to transmit the binary serial data onto the power line. The system also includes a fail-safe construction so that, should the control system fail, the load will be operable. The system provides continuous communication from the controller to the power line, so that should noise interfere with one data transmission, subsequent data transmission will provide correct data to the load, thereby making load control nearly immune to extraneous noise on the power line.

Abstract: A light source including a spiral line pulse generator having an output coupled to one electrode of a high pressure discharge lamp and having an input for coupling to a source of lamp operating power for providing high voltage lamp starting pulses. The pulse generator includes, in addition to a spiral line circuit, a solid state electronic switch for discharging the spiral line pulse generator and a ballast capacitor connected in series with the solid state switch. The spiral line pulse generator preferably has a magnetic core associated therewith for increasing the spiral line inductance.

Abstract: Starting and operating apparatus for high intensity discharge lamps includes first and second pairs of terminals formed for connection to an AC source and a discharge lamp respectively, a series connect ballast means and inductor connected to one of said first pair and one of said second pair of terminals a bilateral switch shunted by a capacitor and in series with an AC impedance coupled to the inductor and to the other one of said first and second pair of terminals whereby relatively wide high voltage, high frequency pulse potentials for starting the discharge lamps are provided.

Abstract: An electronic ballast for energizing one or more gaseous-discharge lamps and for regulating the power consumed thereby, the ballast including a power supply for providing a source of DC power between a pair of outputs, a pair of transistors connected as switches in series between the power-supply outputs, the transistors for selectively coupling to the juncture thereof positive and negative potentials, a voltage-conditioning and current-limiting network for energizing the lamp from the potential developed between the transistor juncture and a power-supply common, and a pulse generator for developing pulses for driving each of the transistors in turn whereby a potential is developed at the transistor juncture which alternates as positive-going and negative-going pulses each separated by a dead time, the pulse generator for monitoring the power consumption level of the lamp and responsive thereto operative to vary the frequency and/or the width of the transistor driving pulses whereby the lamp consumption is re

Abstract: An electronic ballast is adapted for operation on regular 120 Volt/60 Hz power line voltage and comprises: (i) full bridge rectifier means, (ii) ripple filter means consisting of an LC circuit series-resonant at 120 Hz, (iii) push-pull inverter means operating into an LC output circuit parallel-resonant at about 30 kHz and operative to provide a 30 kHz voltage at an output that is substantially balanced with respect to ground, and (iv) means to disable the inverter in case a 30 kHz ground-fault current flows from this output. A key element in achieving high efficiency relates to the use of ground-fault interruption to achieve the required safety from electric shock hazard, thereby obviating the need for the more conventionally used isolation transformer with its attendant added cost and inefficiency.

Abstract: A circuit containing a ballast for one or more fluorescent lamps. The circuit includes a first inductor in series with a voltage input terminal and a first capacitor to form a series resonant circuit to provide a starting voltage to the lamps. A second, shunt inductors coupled between the first inductor and the capacitor and another input terminal of the circuit to eliminate the high Q of the series resonant circuit and prevent the first inductor from saturating. The inductors are mounted on the legs of an H-shaped core to provide inductive coupling between the inductors and allow a maximum winding area for the first inductor to reduce the series resistance of the lamp current path. The core also allows the shunt inductor to adjust power line power factor independently of lamp power factor. Improvements in system efficiency of up to 15% can be achieved over conventional core/coil type ballasts.

Abstract: Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp--the fluorescent lamp being connected in parallel with the tank-capacitor of this LC circuit. In particular, the invention relates to the use of a Varistor coupled in parallel with this tank-capacitor, thereby limiting the voltage developed thereacross to a magnitude suitable for proper lamp starting. Moreover, by providing for means whereby the inverter shuts itself off in case current flows through this Varistor for more than about one second or so (which is the maximum length of time that it should normally take for a fluorescent lamp to start), inverter as well as Varistor overload protection is obtained.