Abstract: An inverter for powering a lamp at deep dim levels. Inverter driving circuitry includes a feedback loop which compares desired dim level to signal representing actual lamp power consumption. Reproducibility of desired lighting conditions for different types of lamps powered by the same ballast over a wide range of temperatures is also provided.

Abstract: A control circuit for controlling the light output level of a dimmable fluorescent light ballast such as the Mark VII ballast manufactured by Advance Transformer, Inc. The circuit operates from power supplied by the Mark VII ballast through a 300 to 500 microamp DC current loop. The control circuit includes a photo sensor that detects the level of ambient light in a room, and in response to the detected light level, the circuit sets a voltage level from 2 and 10 volts between the two output leads for the current loop on the ballast. At 2 volts, the light is at its dimmest level, which is 20 percent of its maximum brightness, while at 10 volts, the light is at the 100 percent level. Between 2 and 10 volts, the light's brightness is set on a linear scale between 20 and 100 percent.

Abstract: A wireless transmitter associated with a switched electrical connection and a receiver therefor, adapted for connection in an electrical path between the source of power and a load, enables the load to be controlled by the switch originally used to control the switched electrical connection. The communication between the transmitter and receiver may be realized only when power is applied or removed from the switched connection, or, alternatively, this communication may be carried out on a per-cycle basis, enabling a phase-delay type of control over the relocated load, including dimming of the relocated load without requiring modification to a previously installed dimmer switch. The signal radiated by the transmitter may be of acoustic or electromagnetic origin, though IR transmissions are used in the preferred embodiment.

Abstract: A method and device for controlling electric discharge lamps with electronic fluorescent lamp ballasts, using a bistable reverse switch system in the electric circuit in such manner that in turning the lamp on to a first switching condition, and after a short period of interruption of the electric circuit to the current supply of the lamp, the bistable reverse switch system acquires a second switching condition. It is thereby possible to reduce the lamp from a first level of brightness to a second lower level of brightness. It has the effect of a "dimmer" used with fluorescent lamps.

Abstract: A system wherein light from a fluorescent lamp is dimmed by modulating the pulse-width of current pulses. A current-command signal is applied to a lamp driver in response to a voltage-level corresponding to a given, selectable level of desired lamp brightness. The lamp driver operates as a flyback AC power source that advantageously uses a FET switch to decouple the lamp and a resonant bridge, with the current-sampling process. The circuit samples only the inductor current while the FET switch is active. Because the sample is decoupled from the lamp and bridge, this sampling provides particularly tight control of the regulation process needed to control the incoming noise and transients that affect the power supplied to the lamps. The lamp driver a can also operate as a synchronously-driven resonant forward converter that senses the current actually supplied to the lamp and responds to changes in the fluorescent lamp's condition since the lamp is coupled to the circuit.

Abstract: A ballast for a gas discharge lamp comprises a resonant load circuit including a gas discharge lamp, and a resonant inductance and a resonant capacitance whose values determine the operating frequency of the remnant load circuit. A d.c.-to-a.c. converter circuit is coupled to the remnant load circuit to provide a.c. current to the remnant load circuit. The converter comprises at least one switch. A high voltage IC drives the at least one switch at a frequency determined at least in part by impedance between a timing input and a ground. A circuit for supplying a d.c. voltage to the d.c.-to-a.c. converter includes (i) a supply path for d.c. current; (ii) first and second return paths for d.c. current; and (iii) an arrangement to selectively make the first return path operable alone, the second path operable alone, and the first and second paths operable together. First and second impedances are coupled between the timing input and the first and second return paths, respectively.

Abstract: A power regulator system provides power to an electrical load. A power level selector generates a reference signal which indicates a desired power level for the electrical load, and a control circuit connected with a AC power source interrupts flow of the AC current for periods of time responsive to a reference system from the power selector. A filtering circuit filters the output of the control circuit and generates therefrom a second output AC circuit which is smooth relative to this interrupted AC circuit. This smooth AC output is applied to the load. A relay is provided to prevent overload conditions from forming adjacent the load in the circuit. Various types of sensors may be used as the power level indicator, such sensors including the light detector as movement detectors, and other electrical sensors.

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

Abstract: A bridge rectifier is connected with a 277Volt/60 Hz power line and provides full-wave-rectified unfiltered DC voltage to a series-combination of: i) an inductor, ii) a full bridge inverter switched in synchronism with the 60 Hz power line voltage, and iii) an electronic switching device. A fluorescent lamp is connected with the inverter's output and receives 60 Hz current of exceptionally low crest-factor, thereby operating at an exceptionally high efficacy. The electronic switching device is normally in a fully conductive state. However, it is controlled--by a photo sensor responsive to the light output of the fluorescent lamp--in such a manner that whenever the instantaneous light output exceeds a certain adjustably predetermined upper level, it switches into a non-conductive state where it remains until the instantaneous light output level diminishes to a certain adjustably predetermined lower level.

Abstract: A voltage-boosting and current-regulating circuit delivers energy from a high voltage resonant circuit source to a fluorescent lamp. A controllable switch is connected in series with the lamp cathodes and is triggered into conduction during a predetermined conductive time interval within each half-cycle of current conducted through the plasma from the resonant circuit. A charging current which flows during the conductive time interval stores energy in the resonant circuit which is subsequently released as a boosted voltage and as increased current flow through the plasma. The boosted voltage allows higher efficiency illumination lamps to the used, and regulation of the conductive time interval achieves the optimal current conduction through the lamp.

Abstract: The present invention is directed to providing building automation systems which can effectively control light output of a building in a manner which can significantly reduce power consumption, yet which goes virtually unnoticed by building occupants. Exemplary embodiments are directed to using existing building automation systems to control the dimming, rather than the turning off, of selected artificial lighting. Further, exemplary embodiments are directed to using the conventional relay network of existing building automation systems to control the dimming of the artificial lighting.

Abstract: A filament-heater power supply includes a combination forward and flyback power converter for supplying electronically variable, isolated voltages to dimmable discharge lamp filaments while supplying a fixed dc output voltage to a ballast control circuit. Hence, only a single ballast power supply is needed. The control circuit controls the level of filament voltage to operate the lamp filaments at an optimum temperature, even during dimming operation, thereby substantially extending lamp life. The filament-heater power supply provides a high degree of isolation among filament voltages while regulating and tracking the voltage across each filament. The filament-heater power supply can preheat the filaments to aid lamp starting, thereby extending the useful life of the lamp, and is also structured to sense when a lamp is not present in a fixture so that high voltage starting pulses are not applied to the terminals of an empty fixture.

Abstract: A method and apparatus for ionizing a rare gas in a gas type cold cathode lighting source using a high voltage direct current pulse. Direct current pulses are applied to the lighting source, the current flow to the lighting source is sensed, upon ionization of the gas the voltage level of the pulse is reduced and the pulse width is increased so as to provide a proportionally increased constant current high voltage direct current pulsed output, and the polarity of the pulses to the light source is periodically reversed.

Abstract: An inverter driving scheme for detecting when an inverter is in or near a capacitive mode of operation. In response to being within a capacitive mode of operation, the switching frequency is immediately increased to its maximum setting. When a near capacitive mode of operation is detected, the switching frequency is increased at a preset rate. During overvoltage conditions across the lamp combined with a near capacitive mode of operation, the switching frequency is immediately increased to its maximum setting.

Abstract: An electronic ballast (200) includes a rectifier circuit (20), an energy storage inductor (38), a power switch (58), a control circuit (50) for driving the power switch (58), a clamp diode (46), a voltage clamping capacitor (54), a bulk capacitor (34), and an output circuit (70) for providing power to one or more fluorescent lamps (100). In a preferred embodiment, the rectifier circuit (20) includes a full-wave diode bridge (22) and a high frequency filter capacitor (24), and the output circuit (70) has a resonant inductor (72), a resonant capacitor (82), and a dc blocking capacitor (88). The ballast (200) provides power factor correction and high frequency power for fluorescent lamps, but requires only a single power switch (58) and a single energy storage inductor (38).

Abstract: An improved ballast circuit for use with a compact fluorescent lamp includes an EMI filter, a rectifier and voltage amplification stage, an active resonant circuit and power factor correction stage which is connected in parallel to a lamp load. The ballast circuit includes a feedback capacitor which provides a feedback path for a portion of the high frequency current to the rectifier and voltage amplification stage. The feedback capacitor of the improved ballast circuit reduces the non-linear characteristics of the diode, thus providing almost a linear load on the input power supply and therefore achieving an improved power factor, on the order of 0.95 or greater. The improved ballast circuit may also include a dimming stage which works with the active resonant circuit to vary the amount of power that is supplied to the lamp load. The dimming stage does not require the addition of parasitic active stages and thus provides a lamp with high electrical efficiency.

Abstract: A lamp controller includes an interface circuit, or receiver, which receives an input signal and decodes control signals supplied from a transmitting device, such as a power line wall controller, according to at least two of the following communication techniques: phase angle control, step control, and coded control. The receiver tests the input signal and identifies which type of control technique is employed by the wall controller connected to the lamp controller. The receiver then decodes the control command from the input signal. In a disclosed embodiment, the lamp controller is gas discharge lamp dimming ballast having a two wire input for connection to the hot dimmed and neutral leads of the power line controller. The ballast has an improved topology in which a pre-conditioner supplies a substantially constant DC voltage to a ballast stage including an inverter, a resonant tank output and a control circuit.

Abstract: An electronic stabilizer having a variable frequency soft start circuit, said circuit having a secondary coil coupled to a drive transformer of the electronic stabilizer. In the initial period when power is connected, the secondary coil may supply an induced voltage to a capacitor to generate a forward voltage to connect primary transistor to allow an inductance element to parallel the secondary coil to reduce the total inductance. The operating frequency of an LC oscillating circuit of the stabilizer hence increases. Relatively, the energy obtainable by the fluorescent lamp is reduced. The soft start circuit is further provided with a discharge loop of a secondary transistor for discharging of the capacitor to ensure that soft starts may be achieved under any conditions.

Abstract: A compact dimmable fluorescent lamp apparatus that connects with at least one fluorescent lamp and with an input power source that supplies an AC input voltage. The lamp includes a rectification stage for rectifying the AC input voltage, a dimming stage for generating a dimming signal indicative of lamp brightness, and a ballast circuit that is in electrical communication with the rectification stage and the dimming stage. The ballast circuit is arranged for connection with the lamp for applying power variably to the lamp and includes a resonant circuit stage that electrically connects with the lamp and that generates a high frequency voltage in response to the input voltage. The resonant circuit varies the level of power supplied to the lamp in response to the dimming signal, thereby attaining a selected level of lamp brightness.

Abstract: A ballast for powering a lamp at deep dim levels. Driving circuitry includes a feedback loop which compares a desired dim level to a signal representing actual lamp power consumption. The loop is closed once the signal representing actual lamp power consumption equals the desired dim level. During ignition, a switch in response to the lamp voltage reaching or exceeding a predetermined threshold opens the feedback loop. The feedback loop is closed once the lamp has been ignited. By closing the loop as soon as the lamp has been ignited, ignition flash is minimized.

Abstract: A dimmer oscillator for a high frequency luminous tube power supply including a frequency shiftable high frequency oscillator, a variable duty cycle low frequency oscillator operatively connected to the high frequency oscillator for controlling the high frequency oscillator between a first normal output operating frequency and a second higher frequency. A low pass filter within the high frequency supply whereby the supply output to a luminous tube load is reduced, when the oscillator is operating at the second higher frequency, to a low intensity ionization maintenance level. An integrator between the low and high frequency oscillators whereby the transition between the first nominal and second higher operating frequencies is smoothed to reduce acoustic noise and false GFI and OVP triggering. A frequency control diode between the low and high frequency oscillators to limit the lower frequency excursion, and to maintain oscillation of, the high frequency oscillator.

Abstract: An apparatus for dimming a discharge lamp is provided which comprises an electromagnetic regulator. The electromagnetic regulator has a primary winding connected to an AC power supply, a secondary winding connected to the lamp, and a tertiary winding. A capacitor is selectively connected to a tap on the tertiary winding via a switching device for dimming purposes.

Abstract: A feedback dimming control circuit for controlling the luminance of a plurality of lamps, the circuit comprising: a multiplier receiving and multiplying a feedback current and an input voltage, a first subtracter generating an error signal by subtracting an output voltage from the multiplier from a reference voltage, a second subtracter subtracting a signal responsive to the error signal from the input voltage, an oscillator generating a periodic signal in response to the output of the second subtracter; and a tank resonating in response to the periodic signal and generating the feedback current.

Abstract: A plurality of spaced ceiling mounted fixtures or other controllable electrical appliances have wide angle radiation detectors mounted within each fixture and wired internally of the fixture to a dimming circuit or to a ballast. The radiation detectors have sensitivity over a wide angle and are fixed over a small opening in the fixture. A narrow beam radiation transmitter selectively illuminates one of the radiation detectors without illuminating the others. The dimming circuits or ballasts within the fixtures can be further controlled by external dimmers, occupancy sensors, timeclocks, photosensors and other types of input devices.

Abstract: A key touch dimmer includes a switching device through which AC line current is passed to brighten a lamp in response to a control signal generated by a microprocessor. The microprocessor receives an input indicative of the zero crossing points of the AC line current and synchronizes this input with its own internal clock circuitry to generate a firing signal for the switching device at the correct phase angle in the next half cycle of the AC line current. The dimmer has memory capability whereby the lamp, when turned back on, will brighten to a preset level. This brightening is accomplished in a gradual manner. Likewise, a turned off lamp will fade to zero brightness, with the dimmer retaining the preset brightness level. The microprocessor shuts down quickly in the event of a power outage to preserve memory. An optional display includes a plurality of LEDs for indicating light level. Other options include providing the dimmer with several keys, each of which can be adjusted to a respective preset level.

Abstract: The present invention teaches a dimmer which incorporates an alternating current (AC) trigger which exhibits asymmetrical electrical characteristics. This eliminates the undesirable snap on hysteresis effect associated with conventional dimmers utilizing symmetrical AC triggers such as diacs and silicon bilateral switches (SBS). One embodiment of the present invention utilizes a zener diode to create the asymmetry. During one polarity of the AC source, the breakover voltage of the trigger is increased, forcing the trigger to breakover at a time later in the AC cycle than it would otherwise have with a symmetric trigger. This compensates for charge dumping of the phase control capacitor into the gate of the triac which would otherwise cause the snap on hysteresis effect.

Abstract: A circuit and method for driving a load such as a gas discharge illumination device from an ac main supply with a high power factor. The circuit includes a pair of electronic switches arranged in a half bridge configuration and a self oscillating driver circuit having two outputs for driving respective ones of the electronic switches, the electronic switches being coupled across a dc bus voltage and having a switched output coupled to the load. The circuit further includes a voltage regulator circuit coupled across the dc bus voltage and coupled to the self oscillating driver circuit, the voltage regulator circuit maintaining the dc bus voltage within a preset range and preventing the dc bus voltage from exceeding the range if the load is removed or becomes an open circuit. The voltage regulator preferably is a boost regulator switching an inductance. The circuit is particularly suitable for driving gas discharge illumination devices, e.g.

Abstract: A dimmable fluorescent lamp system embodiment of the present invention comprises a fluorescent lamp with filaments at each end that are continuously heated by independent secondary windings of a transformer. A resonating capacitor is connected in series with a resonating inductor and a pair of DC blocking capacitors are connected from each end of the fluorescent lamp to put it in parallel with the resonating capacitor. A control logic drives the primary winding with a pulse-width or frequency modulated square wave that is controlled by a feedback voltage derived from a pair of rectifiers and a dropping resistor in series with one of the DC blocking capacitors.

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 control system for gas discharge lamps (5) includes a fuzzy controller (7) which, for controlling the lamp current of the gas discharge lamp, generates a setting value for an inverter (3), for setting the frequency or duty ratio of the lamp current, in dependence upon an actual value of the lamp current. Further, in accordance with the invention, fuzzy logic is employed for the purpose of recognition of the lamp type of a connected gas discharge lamp (5), in that on the basis of various detected operational parameter values, during the operation of the gas discharge lamp, the lamp type of the gas discharge lamp is determined.

Abstract: A dimmer logic for fluorescent lamps is described which operates after the principal of a two-point circuit with two stable operating points, where in dimmer operation periodic changes between the two operating points takes place. By periodically switching on and off the fluorescent lamp the average brightness of the fluorescent lamp is reduced. The dimmer logic can be extended by sensor inputs for current and voltage to control the voltage, current and power. By appropriate design of the dimmer logic a control and protection circuit for overcurrent, overvoltage and overpower can be realized.

Abstract: A preferred embodiment of the present invention provides a ballast circuit, comprising three sections: an input power section that receives a line AC signal as an input and provides a DC signal as an output; a pre-regulator section that conditions the DC signal; and a lamp driver section that drives a gas discharge lamp load. The pre-regulator section includes a transformer with an input winding, an output winding, and a current sense winding. The input winding receives the DC signal provided by the input power section. The output winding is connected in a flyback configuration with a flyback blocking diode, a bulk storage capacitor, and an output terminal for the conditioned DC signal. The current sense winding generates a signal proportional to the level of the transformer current. The transformer current is controlled by a flyback switch. A resonant capacitor is connected between the flyback switch input and ground, the resonant capacitor and the transformer forming a resonant circuit.

Abstract: A compact auxiliary circuit modifies the operation of a low-voltage control circuit associated with an electronic dimming gas discharge lamp ballast. The auxiliary circuit modifies the output of the control circuit to reduce the brightness of the lamps when excess ambient light is available, and increases the brightness of the lamps as available ambient light is reduced. The auxiliary circuit is located in a small housing which mounts in a knockout plug of a fluorescent ceiling fixture. In a preferred embodiment, the auxiliary circuit includes a photocell that obtains information on ambient light levels through an ambient light gathering prism mounted through a ceiling tile near the fixture, and connected to the circuit housing by a flexible fiber optic cable. A single auxiliary circuit according to the invention can be connected to vary the brightness of a large number of lamps.

Abstract: An arrangement for adjusting the intensity of an electrodeless discharge lamp is described. In one embodiment the high-frequency signal delivered to the induction coil is interrupted during a predetermined portion of a full duty cycle. This function is provided by a dimmer control unit which may be in an analog or digital form and may respond to a control signal provided by a potentiometer, a three-way lighting fixture or an addressable, remote controlled interface with data transmitted over the power lines or over a radio or infrared communication channel. In another embodiment the dimmer control unit alters the amplitude of the high-frequency signal supplied to the lamp's induction coil.

Abstract: A gas discharge lamp dimming ballast has a two wire input for connection to the hot dimmed and neutral leads of a phase control dimmer. The ballast has an improved topology in which a pre-conditioner supplies a substantially constant DC voltage to a ballast stage including an inverter, a resonant tank output and a control circuit. A dimming interface circuit derives a dimming signal having a voltage equal to the average value of the rectified output voltage of a full-bridge rectifier feeding the pre-conditioner circuit. The dim signal is independent of the DC rail voltage and, in combination with the maintenance of a substantially constant DC rail voltage, permits of improved dimming control while providing the ease of installation of a two wire ballast. The response time of the interface circuit relative to the pre-conditioner is selected to avoid power imbalances.

Abstract: A modulated electronic ballast for driving a gas discharge lamp includes a full wave rectifier for supplying a modulating signal to a series fed parallel resonant circuit including two transistors. Inductors are provided on both the hot and neutral alternating current power source lines for shielding the power source from electromagnetic interference and providing transient protection. A biasing circuit supplies a small direct current to the resonant circuit for retaining the resonant circuit in a continuous oscillating mode during substantially zero voltage valleys of the modulating signal. A diode is provided across the base and collectors of each transistor in the resonant circuit for preventing over saturation and co-conduction.

Abstract: An electronic ballast (2) which includes an electronic harmonics filter (7), the brightness of a lamp (38) can be determined by employment of a dimmer (1) provided in the mains feed, in that a desired value signal (UM) for setting the frequency (f) of the switch (S) is supplied to the controller (8), which desired value signal depends upon the input or output voltage of a rectifier (4) connected downstream of the dimmer (1), in particular dependent upon the curve form of this voltage.

Abstract: A ballast for driving a gas discharge tube light with overvoltage protection and dimming. A clamp winding coupled to the internal DC power source prevents overvoltage of the secondary terminals by permitting induced current flow in the clamp winding if the clamp winding voltage exceeds that of the internal DC power source. The transformer core includes a shunt leg which supports a dimmer control winding. When the dimmer control winding is open-circuited, magnetic flux is shunted away from the secondary winding, reducing the light intensity; when the dimmer control winding is short-circuited, currents induce in the dimmer control winding prevent substantial of magnetic flux density and increase the light intensity.

Abstract: A control service delivers controlled magnitude energy from a sinusoidal power source in the form of a sequence of pulses conforming to the sinusoidal envelope. A gate signal operated at a selected frequency applies gating pulses to a gating device receiving the sinusoidal power signal and applying its output to a load. The load receives, at high gate signal frequencies, substantially all energy presented in the power signal and, at lower gate signal frequencies, a selected magnitude energy taken from the sinusoidal power signal. The power applied to the load does not produce undesirable noise or radio frequency interference and does not require use of an expensive, heavy and volumous choke or inductor.

Abstract: A monolithic MOS gate driver chip is described for driving high side and low side power MOSFETs in a gas discharge lamp ballast circuit. The chip includes a timer circuit for generating a square output at the natural frequency of resonance of the lamp ballast. Dead time circuits are provided in the chip to prevent the simultaneous conduction of both high side and low side MOSFETs. The chip may be housed in a right pin DIP package.

Abstract: An electronic ballast includes a converter coupled to a variable frequency inverter and a series resonant, parallel loaded output coupled to the inverter. The frequency of the inverter increases when the supply voltage from the converter decreases. The converter includes a full wave rectifier producing a first voltage and an unregulated boost circuit producing a second voltage which is combined with the first voltage to produce the supply voltage. The amount of boost, and therefore the magnitude of the supply voltage, is varied to provide dimming. Dimming is controlled mechanically, via a potentiometer, or electrically, via a control input. Dimming also occurs in response to changes in the first voltage, i.e. from changes in the voltage on an AC power line or from changes in the voltage provided by a capacitive dimmer coupled between the ballast and an AC power line.

Abstract: A dimming control circuit for connection to a nondimming ballast in a fluorescent lighting system is disclosed herein. The control circuit is switchably connected to a source of AC voltage within the lighting system, while the ballast includes terminals for connecting to a fluorescent lamp. A power control module within the control circuit is operative to conduct a controllable portion of the voltage waveform provided by the source of AC voltage to the ballast in accordance with a brightness control signal received by a phase control circuit. A turn-on module, operatively coupled to the power control module, operates to shunt current from the phase control circuit during a turn-on interval commencing upon connection of the dimming control circuit to the source of AC voltage in order that substantially the entire voltage waveform is provided to the ballast during the turn-on interval.

Abstract: A DC/AC convert circuit for operating a discharge lamp includes a branch A having ends suitable for connection to a DC voltage source and comprising a series circuit of two switching elements for generating a periodic voltage by being conducting and non-conducting alternately at a frequency f, each switching element being shunted by a diode. A control circuit is coupled to control electrodes of the switching elements for rendering the switching elements conducting and non-conducting alternately at the frequency f. A load branch B shunts one of the switching elements and comprises an inductor. The discharge lamp is coupled to the load branch B. The power consumed by the discharge lamp is adjusted by adjusting the value of the difference Tt-Td, in which Tt is a time interval during which one of the switching elements is conducting during a half cycle of the periodic voltage, and Td is the time interval during which a diode is conducting during the same half cycle of the periodic voltage.

Abstract: Reverse phase-controlled dimming of an a.c.-powered load is accomplished by switching power to the load on and off during each half cycle. In one embodiment of the present invention, power is switched on when line voltage is substantially equal to load voltage and off at a selected time later in the half cycle or at any time that the voltage across the switch exceeds a predetermined value. Preferably, switching is accomplished with a pair of field effect transistors. The load preferably includes a capacitor from load hot to neutral. The present circuit permits quiet dimming of incandescent lamp loads without the need for complex circuitry. It is particularly well adapted for dimming low voltage lamps using a converter solid state transformer.

Abstract: A control system for a plurality of switched loads includes an AC line and a neutral wire and a pair of loads coupled in parallel between the AC line and the neutral. The switched loads may be operated so that one load in the pair operates in forward phase control mode and the other load in the pair operates in reverse phase control mode. This reduces harmonic current in the neutral wire otherwise resulting from odd order harmonics generated by the switching of AC current into the load during normal operation.

Abstract: A dimmer circuit for gas discharge lamps, having an electronic ballast equipped with a first converter circuit which first transforms an applied voltage by means of switching transistors into a first high-frequency alternating voltage. This first high-frequency alternating voltage is fed indirectly or directly to the gas discharge lamp. The dimmer circuit also includes a second converter circuit connected upstream. The second converter circuit is arranged so as to transform an input voltage into a second high-frequency alternating voltage and is also arranged so as to rectify the second high-frequency alternating voltage to produce a rectified output voltage. After rectification, the rectified output voltage is fed to the first converter circuit as the above-mentioned applied voltage. The second converter circuit contains switching means which, operated manually or by remote control, influence the magnitude of the rectified output voltage from the second converter circuit.

Abstract: A switchmode AC power controller for controlling the current through a load such as a large lamp array connected to an alternating current source. The controller contains an AC solid state switch, a synchro-flywheel, an output inductor and capacitor. The load current is controlled by triggering signals generated by a synchronized modulator.

Abstract: A lighting system comprises a number of central power supplies, with each central power supply being powered from a 277 Volt/60 Hz power line and operative to provide a voltage output of 277 Volt RMS magnitude and 30 kHz frequency to each of a plurality of special incandescent lighting fixtures.Each special lighting fixture comprises: i) an incandescent lamp designed to be properly powered by a voltage of 24 Volt RMS magnitude, and ii) a transformer operative to convert the 277 VoltRMS/30 kHz voltage to a 24 VoltRMS/30 kHz voltage.The reason for using 24 Volt incandescent lamps is that, at the lumen output levels normally required of light bulbs used in general lighting applications, an incandescent light bulb designed for and operated on 24 Volt RMS exhibits substantially higher efficacy and/or durability for a given lumen output level as compared with a light bulb designed for and operated on 277 Volt RMS (or 120 Volt RMS).

Abstract: To provide for dimmer operation of a fluorescent lamp (L) with a minimum of circuit components, the d.c. output level at an output terminal (C1) of an energy supply source, such as a switched mode power supply (10, 10'), is controlled in accordance with the setting of a dimmer control (D). The voltage level at the output capacitor (C1) of the switched mode d.c. power supply furnishes supply voltage for an inverter (T1, T2) coupled to the discharge lamp. During lamp operation, a control unit (R) controls the level of the d.c. voltage supply for the inverter in accordance with the dimmer setting. This permits change of the brightness of the fluorescent lamp (L) in a range of from 5% to 100% of nominal value. Preferably, control of the supply voltage for the inverter is activated only upon occurrence of the ignition or arc-over phase, for example under control of a timing circuit (ZS), controlling a relay in the preheating circuit of the lamp.

Abstract: An EL lamp characterized by non-linear brightness decay is driven to constant brightness for the life of the lamp by an inverter controlled by a microprocessor. The microprocessor controls the inverter in accordance with a table containing data which is the inverse function of the non-linear brightness decay. The microprocessor tracks the total on-time of the EL lamp and selects the appropriate data from the table for driving the lamp. Control can be analog or digital. If control is analog, the selected data is coupled to a D/A converter which is coupled to the inverter. If control is digital, the selected data is coupled to a counter driving a pulse width modulator which is coupled to the inverter. In accordance with another aspect of the invention, an EL lamp is dimmed a precise amount based upon the data in the table and the EL lamp can be dimmed in unison with other lamp types, each lamp type having a table containing data for dimming.