Abstract: A current supplied to a discharge lamp (100) is an A.C. current having a predetermined frequency from an inverter circuit (70), and its power control is carried out by changing the current setting (setting signal) of a chopper circuit (40) constituting a constant current circuit. When a value is set by an output luminance regulator (120), this set current value is inputted to a chopper control circuit (130). The chopper control circuit (130) checks the current detected by a current detector (110) and outputs a current control to a gate terminal (41) of the chopper circuit (40) so that the output current may coincide with the set current value. Accordingly, the power supplied from the inverter circuit (70) to the discharge lamp (100) is controlled by the chopper circuit (40).

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: A power supply circuit (100) for use in driving fluorescent lamps (102, 104, 106) has a current mode control voltage boost IC (144) which produces a boosted voltage and has a power control input (pin 3) and a frequency control input (pin 4). The lamps are driven by a self oscillating inverter (178, 180, 196, 198) which is powered from the voltage boost IC and which operates at a frequency independent therefrom. In order to dim the lamps a D.C. bias voltage is applied to the power control input. At the same time a commensurate D.C. bias voltage is applied to the frequency control input so as to provide power factor correction in dependence on the power produced by the voltage boost IC. The circuit thus provides a substantially constant, optimum power factor at both full and dimmed light levels.

Abstract: A lighting system comprising: an AC power line; an electronic ballast including structure for receiving and interpreting commands transmitted on the power line to control dimming of a fluorescent lamp, the ballast including structure defining an individual address, the ballast including structure for initiating an arc to start the fluorescent lamp, for limiting current through the fluorescent lamp after the arc is initiated, and for dimming the light output of the fluorescent lamp; and a control element spaced apart from the electronic ballast and including structure for sending commands on the power line in a format that the ballast is capable of interpreting, the control element including structure for sending an address with the command, the ballast including structure for comparing the sent address with its individual address and responding to the command if the sent address matches its individual address.

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: A self-contained programmable actuator can easily be mounted directly onto the outside of the face plate of a standard wall switch having a built-in light dimmer. This actuator can be programmed to adjust the position of the dimmer's mechanical control input in accordance with a program that automatically repeats on a diurnal, weekly or other cyclical basis. The actuator includes a small battery, a miniature electric motor with a gear/linkage mechanism operable to engage with and to move the dimmer's mechanical control input over its complete range, and a quartz-clock-based programming means having programming intput keys and time display means.Once programmed by way of the programming input keys, the programming means is operative to actuate the electric motor in such manner as to move the dimmer's mechanical control input in accordance with the keyed-in program.

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 lighting system comprising lighting units each provided with a lamp and a control device for controlling the luminous fluxes of the lamps. The control device includes a first adjustment device (II) for selecting a lighting mode of the lighting system and a further adjustment device (III) for changing a desired luminous flux value in a chosen location illuminated by at least one lighting unit of a first group of the lighting units within a lighting mode. The system is also provided with a correction device (IV) for automatically changing the luminous fluxes of the lighting units of a second group of lighting units dependent upon a change in the desired luminous flux value at the chosen location. In the case of a change in the task lighting by the user (the luminous flux of a first group of lighting units), the surround lighting (the luminous flux of the second group of light units) is changed so that a good harmony between task lighting and surround lighting is maintained.

Abstract: A ballast circuit uses an optocoupler to provide electrical isolation of the dimming control from the remainder of the ballast. The optocoupler is operated in the linear range to provide continuous dimming of the lamps. The circuit further uses a combination of diodes and a diode bridge to steer current from the current sensor during lamp out conditions so that the inverter will maintain operation at a low frequency, thereby maximizing the output voltage. A clamp winding is used to insure that the voltage does not exceed the DC rail voltage.

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 relatively high efficiency, relatively light weight, relatively small electronic ballast or AC power controller for use in aircraft and elsewhere for controlling a fluorescent lamp load or other load includes an EMI filter, a multi-purpose transformer, a power conversion stage and a control circuitry stage. The ballast or controller operates to increase or decrease the voltage of the incoming sine wave AC voltage through a charging path for an energy storage inductor choke cooperating with an energy storage capacitor wherein the charging path for the capacitor is different from the discharge path of the capacitor to isolate the load from the charging of the capacitor and thus to provide an output to the load which is independent of the charging path and which is out of phase with the incoming waveform.

Abstract: A regulated and constrained current source is used to drive the cathodes of a hot cathode gas discharge lamp to provide heating during lamp operation. In one embodiment, the regulated current source is time shared between the lamp cathodes and the lamp arc.

Abstract: An electronic device (100) is disclosed including an electroluminescent (EL) backlight panel (140) and an EL driver circuit (210). The EL driver circuit (210) provides power to the EL backlight (140), as well as panel aging compensation and user adjustment capabilities. The EL driver circuit (210) is low-cost, small-size, and designed in such a way to be easily integrated into a custom integrated circuit. A method is provided for controlling and converting power to the EL backlight panel (140).

Abstract: A simple and compact magnetic ballast for powering a wide range of fluorescent lamp load Wattage such as 14 Watt to 60 Watt without need for modification to the ballast unit. Arc current to the lamp load is supplied through a saturable reactor including a power winding on a magnetic core. Arc current delivered to the lamp load is a function of magnetic saturation of the core determined by a control current through a control winding on the core. In one application, multiple fluorescent lighting fixtures of different wattages illuminating the interior of an aircraft cabin are each powered by essentially identical ballast units for easier installation and maintenance of the cabin lighting.

Abstract: A lighting control system is adapted to dim a plurality of groups of light sources in a room to any one of a number of different preset levels to achieve a like number of different lighting scenes. Each group of light sources defines a lighting zone of the same type of light source, for example, incandescent lamps, fluorescent lamps, neon lights, etc. The system includes a plurality of dimmers for adjusting the respective light levels of the different lighting zones, and a display panel for displaying the instantaneous light level of each zone. According to the invention, a suitably programmed microprocessor or the like operates to normalize the system's dimming performance for a plurality of different types of light sources so that a given change in dimmer setting produces the same change in perceived light level from each of the different types of light sources.

Abstract: A processor controlled fluorescent lamp dimmer circuit is shown for use in an aircraft display system utilizing a fluorescent lamp in the backlight system of individual LCD display devices. By use of a processor control dimming circuit in control over each LCD display, greater flexibility, e.g., as by adjustment in software parameters, is made possible in the operation of a dimmer control circuit. The dimmer control circuit reacts to such conditions as ambient light within the aircraft cockpit, fluorescent lamp light energy output, and fluorescent lamp temperature to provide substantially consistent actual and perceived luminance on the LCD display as a function of such detected conditions. Furthermore, the processor control achieves the desired luminance without over-driving, and therefore deteriorating, the lamps. As a result, the pilot of the aircraft enjoys a more reliable and consistent LCD display and need not be distracted by variation in luminance of the LCD display in operation of the aircraft.

Abstract: A lighting control system which comprises an AC mains power point, power distribution means coupled to the AC mains, a dimmer assembly comprising one or a plurality of co-located dimmer circuits each coupled to the distribution means to receive AC power therefrom, and each comprising an output port developing an AC power signal of frequency corresponding to the AC mains, each said dimmer circuit comprising a current path between the distribution means and the output port, a switching means located in the current path so as to controllably interrupt passage of current, switch driving means supplying a control signal to the switching means to cause it to interrupt the current path a multiplicity of times within each AC half cycle, and filtering means in the current path between the switching means and the output port arranged to smooth the current therethrough, the filtering means being arranged to attenuate current components at the frequency of operation of the switching means, and not substantially to attenu

Abstract: A circuit arrangement for operating a discharge lamp by means of a high-frequency current includes a switching device for generating the high-frequency current from a supply voltage, a modulator for the substantially square-wave modulation of the amplitude of the high-frequency current at a modulation frequency f, and an apparatus (M) for limiting the interference with infrared systems caused by the discharge lamp. The limiting apparatus (M) comprise a circuit N for providing a gradual increase in the rate at which the amplitude of the high-frequency current decreases at the end of a square wave of the square-wave modulation. This provides a considerable reduction in the interference with infrared systems caused by a lamp operated by the circuit arrangement.

Abstract: A fluorescent lamp control circuit includes a dimmer and a sensor. The dimmer is electrically connected in parallel with the fluorescent lamp. The sensor is electrically connected in parallel with the dimmer and lamp. The dimmer adjustably controls the brightness of the lamp when an operating voltage is applied to the lamp. The sensor electrically disables the dimmer when a starting voltage is applied to the lamp and electrically enables the dimmer when an operating voltage is applied to the lamp. The sensor includes a voltage controlled switch, a voltage regulator, a direct current power supply, and a voltage controlled trigger. An output of the voltage regulator is electrically connected to an input of the voltage controlled switch. The voltage controlled trigger is electrically connected between an output of the direct current voltage supply and an input of the voltage regulator. The dimmer includes a current controlled switch, a variable phase-shift (RC) network, and a voltage controlled switch.

Abstract: Light control apparatus and method in which commanded changes in luminance in a space are executed in accordance with a rate function generated by a function generator to correspond to adaptability of the human eye to changes in luminance. A luminance sensor detects the luminance to which a person occupying the space was exposed just prior to the commanded change in luminance. The sensed luminance is used to determine the discrimination range of the occupant, and, upon a commanded increase in luminance in the space, the luminance is immediately increased to within the range.

Abstract: A pre-converter is connected with AC power line voltage and provides DC voltage across a pair of DC terminals. A current-limiting inductor, a self-oscillating parallel-resonant inverter, and a periodically activated FET switch are series-connected with one another across the DC terminals. The inverter provides a high-frequency (e.g., 20-30 kHz) substantially sinusoidal output voltage across its output terminals. Each of plural rapid-start fluorescent lamps is connected across the output terminals by way of a current-limiting capacitor. The magnitude of the resulting lamp current depends on the RMS magnitude of the output voltage. In turn, for a given load condition, this RMS magnitude depends on the average magnitude of the unidirectional current drawn by the inverter from the DC terminals; which average magnitude is determined by the ON/OFF duty-cycle of the FET switch. The FET switch is turned ON/OFF at twice the frequency of the inverter's output voltage.

Abstract: An apparatus is provided for controlling the luminous output of a fluorescent lamp over a wide dimming range. The luminous output is controlled by controlling the lamp current, while the lamp is immersed in a lateral electrostatic field. The lamp and external electrostatic ionization electrodes are driven by a true analog voltage-to-current converter that has a dynamic range inherently wider than conventional PWM circuits. A modified, transformer coupled, push-pull converter with an analog-current-driven primary circuit is used in one embodiment of the apparatus. The lamp driver must be capable of providing a high compliance voltage consistent with the I-V profile of the lamp. A subordinate primary winding on the transformer may be used to reduce magnetization current and to supply sufficient energy for supporting the lateral electrostatic field that is generated by the ionization electrodes which may be printed on a PWB mounted behind the lamp.

Abstract: A circuit for high-frequency operation of a discharge lamp. The circuit includes a load branch provided with terminals for connection to the discharge lamp and with an electrode heating transformer having a primary winding and secondary windings. Each secondary winding is shunted by a branch comprising an electrode of the discharge lamp. At least one switching element generates a high-frequency current through the load branch from a supply voltage. A control circuit generates a control signal for rendering the switching element conducting and non-conducting at a high frequency. A dimmer circuit is coupled to the control circuit for adjusting the frequency of the control signal. Each branch shunting a secondary winding of the transformer also includes an inductive element and a capacitive element and has a resonance frequency which is different from the resonance frequency of the load branch.

Abstract: In an electronic ballast, an L-C series-resonant circuit is connected across the output of a full-bridge inverter while two Rapid-Start fluorescent lamps are series-connected across the tank capacitor of the L-C circuit. The full-bridge inverter is driven in such manner that the inverter's output voltage consists of a series of rectangular voltage pulses of alternating polarity and controllable width and frequency. When the lamps are fully powered, the inverter's output voltage consists of alternating pulses of frequency about equal to the natural resonance frequency of the L-C circuit and with each individual pulse-width about equal to half of the fundamental period of the natural resonance frequency of the L-C circuit.

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 self-dimming electronic ballast for a gas discharge lamp includes a converter having an unregulated boost circuit coupled to a variable frequency inverter having a series resonant, parallel loaded output. The inverter includes a variable frequency driver circuit having a timing circuit for determining the frequency of the driver. A transistor in the timing circuit operates as an inverting amplifer and is controlled by a signal proportional to the voltage of the AC line. The frequency of the inverter increases with decreasing voltage on the AC line. The ballast can be on the same circuit as incandescent lamps and powered by a triac or variac dimmer for dimming both the incandescent and gas discharge lamps.

Abstract: A stabilizer circuit includes a double stabilization device having two active terminals exchangeable with each other when a power switch is turned off and turned on one time, a relay has a coil connected to one of the terminals of the double stabilization device, two capacitors or inductors are connected to the lamp and coupled to the coil of the relay, and have different capacitances or inductances, such that the output energy and the lightness of the lamp can be adjusted.

Abstract: A versatile electrical circuit for controlling the operation of a variety of high intensity discharge, high and low pressure sodium, mercury vapor, metal halide, or xenon arc lamps uses a pulse-width-modulator to regulate the alternating or direct current drawn through the lamp from a regulated power source in accordance with the lamp power rating and the desired light intensity setting and in response to the current sensed through the lamp, and may be powered by an AC or DC power source. The circuit uses a H-bridge to apply an alternating voltage to the lamp that does not include any transformer.

Abstract: A circuit (100) for powering fluorescent lamps (102, 104 & 106) includes a switch (50) having "open" and "closed" positions. When power is initially applied to the circuit, the lamps are powered at full power to enable them to "strike". After a short period, the power is reduced to the lamp. A control circuit (300) thereafter senses if the switch has been "toggled". If toggled, the power to the lamps is increased, and the lamps brighten. The circuit uses a conventional two-position switch and conventional wiring and avoids the need for additional switches and additional wiring.

Abstract: A method and apparatus for automatically adjusting the light intensity output of a fluorescent lamp of a document scanner. The fluorescent lamp current level control apparatus comprises preheating circuitry for applying low voltage pulses of alternating polarity across filaments of the lamp, the low voltage pulses sufficient to preheat the filaments but insufficient to cause the lamp to fluoresce; high voltage circuitry for applying high voltage pulses of alternating polarity across the lamp, the high voltage pulses sufficient to cause the lamp to fluoresce; and control circuitry for receiving a first signal (PWM (D)) indicative of a desired level of current in the filaments, sensing a current indicative of the actual level of current in the filaments, and controlling the high voltage circuitry to cause the actual level of current to tend toward the desired level of current.

Abstract: A dimmer control circuit for application to a load bank produces a sinusoidal power wave form exhibiting the desirable characteristic of suitable rise and fall times producing little or no audible or radio frequency interference. A pair of MOS-FET power devices operate in a linear mode and attenuate respective half-cycles of a single phase power line as a function of a dimmer control signal applied thereto. The device includes a mechanism for avoiding damage to the power MOS-FET by controlling conditions under which a signal change is applied to the gates of the MOSFETs, and by imbalanced attenuation between the MOS-FETs through the range of the dimmer control signal.

Abstract: An energy-saving lighting control system is selectively operable in either a normal mode, in which certain lighting parameters (e.g., maximum and minimum light levels, fade rates, etc.) are preset and lighting level is determined by which of a plurality of inputs requires the least electrical power, or in an off-normal mode (e.g., a calibration or light-adjustment mode) in which certain parameters are adjustable by manually adjusting the position of a movable member, such as a wiper blade in a potentiometer. A microprocessor-based logic and control unit is adapted to automatically switch from the normal operating mode to the off-normal mode in response to movement of the movable member. After a predetermined time period following the most recent movement of the movable member, the logic and control unit stores the new level of the adjusted parameter, and returns to the normal operating mode. Preferably, the system has multiple outputs by which different types of fluorescent lamp ballasts can be controlled.

Abstract: An electronic ballast for discharge lamps comprises an open loop configuration of an impedance converter first stage and an inverter second stage linked by a limiting control stage. The impedance converter stage presents its load, passive or active, as input resistance. It draws a continuous current, through large RFI/EMI suppressing input inductors, which is switched discontinuously through a tank circuit using an energy transfer relationship based on the switch on-time and the inductance and capacitance of the tank circuit. The impedance converter stage supplies unregulated power to the inverter stage which operates stably at a fixed frequency. If an imbalance such as an overcurrent condition or an overvoltage condition develops in the system, the limiting control stage temporarily preempts the converter switching until stability is reestablished.

Abstract: A luminaire of variable color temperature is arranged for emitting blended color light from luminaire section, with color temperature control signals so transmitted from control section to luminaire-lighting section as to substantially equalize respective differences in reciprocal color temperatures of respective two adjacent stages of the color temperature control signals, to thereby render blended state of emission colors to be variable and a dimming of the blended color light to be realized with the color temperature gradually varied in smooth manner.

Abstract: A device for regulating the intensity of light emitted by a lamp includes a core of magnetic material, a first electrical circuit having a primary inductor wrapped around at least a portion of the core of magnetic material, and a second electrical circuit having a secondary inductor wrapped around at least a portion of the core of magnetic material. The first electrical circuit is designed for electrical connection to the lamp, and the primary inductor is arranged in the first electrical circuit in a manner such that a variation in the inductance of the primary inductor will cause a corresponding variation in the intensity of light emitted by the lamp. The second electrical circuit includes a control device (e.g.

Abstract: Provided is a method and apparatus for statistically distinguishing input signals on the lamp lines of an instrument panel dimming circuit to generate a common dimming signal. The method and apparatus sample input signals to statistically determine the waveform of the input signal, i.e., direct current or pulse wide modulated signals thus obviating the need for trapping jumpers and associated electronics which require additional assembly time and manufacturing costs.

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: An operating circuit arrangement for a discharge lamp has a chopper circuit and an inverter circuit. The inverter circuit generates a high frequency voltage to start and operate the discharge lamp. The chopper circuit supplies a d.c. voltage to the inverter circuit. The circuit arrangement has a chopper control circuit and an inverter control circuit which are coupled to the chopper circuit so that the operation of each control circuit responds to the chopper circuit. In order to perform a soft starting operation in which the inverter circuit generates a given high frequency voltage to start and operate the discharge lamp prior to the generation of a given level of d.c. voltage generated by said chopper circuit, an inverter control circuit coupled to the inverter circuit is provided.

Abstract: A bi-level control system includes a plurality of slave units, each for connection to a respective ballast and HID lamp of a plurality of HID lighting fixtures, and a common control unit. Each slave unit includes a switched capacitor and a slave relay which has one input connectable to a common line of an AC power supply branch circuit powering the fixtures and another input adapted for receiving a line voltage signal. The control unit includes an output connected to the control inputs of each of the slave units by a single control line and switchably connected to line voltage. Dimming of the HID lamp is accomplished by switching line voltage to the output of the control unit which causes the slave relay to switch the slave capacitor into circuit with the HID lamp and ballast. Use of a single control line connecting each of the slave units to the control unit greatly reduces wiring over known systems.

Abstract: A control circuit for reducing current flow through the UV light bulb of a water purification unit when water is not flowing through the unit. In a first embodiment, the control circuit includes an RC shunt selectively connected in parallel with the UV bulb, thereby selectively adding a positive impedance in parallel with the negative impedance of the bulb. In a second embodiment, the control circuit includes an impedance selectively connected in series with the bulb ballast. In either embodiment, the impedance circuit is actuated in response to a water flow switch. When water is flowing through the unit, the impedance is removed so that full current is delivered to the bulb enhancing UV intensity. When water is not flowing through the unit, the impedance is added so that current flow is reduced.

Abstract: A dimming control circuit for a plurality of lighting fixtures includes a separate semiconductor power switch, e.g., a silicon-controlled rectifier or SCR, for providing controlled amounts of pulsed, unidirectional electrical current to each lighting fixture. In one embodiment, a pair of SCRs, arranged in parallel, opposed relationship, are controllably pulsed to produce an alternating sequence of positive and negative electrical current pulses, of independently-controlled duration, and oppositely-conducting diodes then connect these SCRs to two separate lighting fixture. One such lighting fixture thus receives the positive current pulses, and the other such lighting fixture thus receives the negative current pulses. In an alternative embodiment, each lighting fixture receives pulsed, unidirectional current directly from a separate, independently-controlled SCR.

Abstract: The present invention is directed to an electronic ballast system including one or more gas discharge lamps which have two unconnected single electrodes each. The system is comprised of a housing unit with electronic circuitry and related components and the lamps. The system accepts a.c. power and rectifies it into various low d.c. voltages to power the electronic circuitry, and to one or more high d.c. voltages to supply power for the lamps. Both the low d.c. voltages and the high d.c. voltages can be supplied directly, eliminating the need to rectify a.c. power. The device switches a d.c. voltage such that a high frequency signal is generated. Because of the choice of output transformers matched to the high frequency (about 38 kHz) and the ability to change frequency slightly to achieve proper current, the device can accept various lamp sizes without modification. The ballast can also dim the lamps by increasing the frequency. The device can be remotely controlled.

Abstract: The invention pertains to a switchmode DC to AC converter, and particularly to a master-slave half-bridge converter. The slave half-bridge power converter is controlled by a lower power self-oscillating half-bridge master converter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially, for high pressure sodium lamps, completed by a high voltage ignition apparatus. A pair of self-saturated electronically switched transformers controlled by a low power current source provide a power controlled and frequency modulated high frequency ballast for the gas discharge devices.

Abstract: A stable output, widely dimmable light source (20) utilizing a gas discharge lamp (14) including an external igniter (12) which is utilized to provide lamp ignition at approximately the same time as an AC potential source (22) provides power to the lamp (14) cathodes. A high voltage pulse is applied to the external igniter (12) causing ionization of the lamp gasses at the start of each time period during which the ballasted AC potential source (22) is applied to the lamp (14). Average light output level is controlled by a light output selector (36) which controls lamp on time and thus the average light output of the lamp (44). During operation lamp (14) is turned on several times per second, such as sixty-eight and the AC potential source (22) has a relatively high frequency, such as 45 KHz.

Abstract: A compact low-pressure gas discharge lamp assembly includes a base and a plurality of low-pressure gas discharge light generating elements mounted to the base. Each of the light generating elements is capable of being individually energized. A ballast circuit is provided which is capable of supplying electrical energy to a variable number of the low pressure gas discharge lighting elements. A three-way switch has an input connected with the ballast circuit and two outputs. Each output is connected with a different light generating element. The switch connects one of the outputs with the ballast circuit in a first switch position and another one of the outputs with the ballast circuit in a second switch position. Both of the outputs are connected with the ballast circuit in a third switch position. The ballast circuit includes an oscillator that oscillates at a frequency that varies as a function of the number of light generating elements connected by the switch to the ballast circuit.

Abstract: An improved dimmable dual filament fluorescent lamp including a first filament and a second filament with automatic current switching between the first element and the second element when the first element opens due to a failure and further having a separating cold cathode getter plate disposed between the first filament and the second filament.

Abstract: A voltage to pulse-width conversion circuit includes a logarithmic clock generator for receiving a reference frequency signal and generating a logarithmic clock signal TCK; a counter for counting the number of clock pulses of the logarithmic clock signal TCK and outputting a digital value having a plurality of bits; a digital to analog converter for converting the digital value into an analog signal; and a voltage comparator for comparing the output signal of the digital to analog converter with a pulse width modulated control voltage and generating a pulse width modulated output signal with a predetermined duty ratio.

Abstract: A circuit for starting and operating a discharge lamp, such as a compact fluorescent lamp, at high frequency from a 60 Hz AC supply. The circuit includes a DC power supply coupled to a pair of AC input terminals for generating a DC voltage. An oscillator coupled to the DC power supply includes a pair of semiconductor transistors and a drive transformer having a primary winding and at least one secondary winding. A load coupled to the output of the oscillator comprises a series combination of the primary winding of the drive transformer and a tank circuit including a tank inductor and a tank capacitor. Suitable means for connecting a discharge lamp in parallel with the tank capacitor is provided. An oscillator sensing and controlling circuit responsive to various lamp failure modes is coupled to the secondary winding of the transformer and reduces the output of the oscillator after a predetermined time delay by shunting the base of either one of the semiconductor switches of the oscillator.

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

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