Abstract: The inverter for multi-tube type backlight includes two step-up transformers of one-side grounded type, wherein the two step-up tranformers respectively output electric power to one or a plurality of cold cathode tubes, and wherein outputs of the two step-up tranformers are of identical frequency but of mutually reversed phases.

Abstract: An arc lamp igniter circuit (10) employs a resonant inverter circuit (16) to convert low-voltage DC to a relatively high-voltage, 80 kilohertz sinusoidal AC voltage that is rectified and voltage-doubled (42, 44, 46) to about 2,500 volts DC for repetitively charging an igniter capacitor (50) until it discharges through a spark gap (58) and a primary winding (54) of a compact, low-mass igniter transformer (52). A secondary winding (56) of the igniter transformer provides repetitive 20 kilovolt pulses, which are sufficient to ionize a metal halide arc lamp (14), causing it to ignite and produce intense illumination.

Abstract: To effectively suppress glow discharge of a discharge lamp, especially a h-pressure discharge lamp, immediately after starting or firing, the lamp is supplied in a second, or run-on phase with a run-up current which has a form factor F greater than one (1), for example 1.13 to 1.45, and which has an effective value I.sub.eff which is higher than the rated normal operating current of the lamp. A control circuit (C), coupled to a controllable power supply, and to a switchable bridge circuit, controls the frequency of the run-on phase current to be higher than the normal operating frequency, for example about 2 kHz with a normal operating frequency between about 90-150 Hz.

Abstract: A FIFO memory (4) provides serial to parallel and parallel to serial data conversion. A read frame buffer (40) and a write frame buffer (30) are coupled with a RAM array (22). Serial input data is stored temporarily into the write frame (30) of fixed width, n bits wide. Then, the entire n bit wide frame of stored serial input data is written into RAM array (22) at once in parallel. Data read in parallel from RAM array (22) is stored temporarily into the read frame (40) and thereafter provided serially to the FIFO output (53). By converting serial input to parallel input, overall chip size is reduced by reducing the number of pointers required because it is not necessary to address the RAM (22) individually when serially writing data into it. The read frame (40) coupled to the write frame (30) and to the serial input data. This allows data written into the FIFO to be immediately available and allows the read frame (40) to receive backfilled data from the write frame (30).

Abstract: A ballast circuit arrangement with hot restrike capabilities includes an input transformer having a primary winding receptive of line power and a secondary winding over which an output voltage is made available. A first capacitor coupled across the secondary winding of the input transformer develops a voltage charge thereon. A resistor and a second capacitor are series connected to one another and are parallel coupled across the first capacitor. A starting aid device is coupled to the secondary winding of the input transformer and produces an output voltage of a predetermined magnitude. The output voltage of the starting aid is coupled to a spark gap device having first, second and third electrodes associated therewith. A first spark gap formed between the second and third electrode is first fired by the output voltage of the starting aid which in turn triggers the firing of a second spark gap formed between the first and second electrodes.

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

Abstract: A circuit for driving gas discharge lamps has a bandpass filter coupled between the output of the inverter and the inverter control. The bandpass filter provides protection against the diode operation of the gas discharge lamps. The bandpass filter is composed of a capacitor and the permeance inductance of a transformer.

Abstract: Here is disclosed a push-pull inverter used to drive a cold cathode discharge tube, a hot cathode discharge tube and the like, comprising a boosting transformer having a first primary coil, a first secondary coil, a second primary coil and a second secondary coil; first and second switching elements each having a control electrode adapted for controllably interrupting primary current flowing through said first and second primary coils; a capacitor connected between the respective control electrodes of the respective switching elements; and a feedback circuit in which one end of the first secondary coil is connected to the control electrode of the first switching element and one end of the second secondary coil is connected to the control electrode of the second switching element so that load current from a load connected between the other ends of the respective first and second secondary coils flows through the capacitor.

Abstract: The ballast is connected between the fluorescent lights and a source of power for the fluorescent lights. The source of power provides an input signal having a first waveform, usually a sine wave, at a first frequency. The ballast consists of a converter for coverting the first waveform to a second waveform at a second frequency different from the first frequency. A distribution arrangement distributes power to the fluorescent lights. The distribution system consists of a transformer, and capacitors are interposed between selected windings of the secondary of the transformer. In one embodiment, the sine wave is converted to a square wave by the converter and to a saw tooth waveform by the capacitors in the distribution arrangement so that the fluorescent lights are fed with the saw tooth waveform.

Abstract: The inverter circuitry requires minimal operating input power, is power factor correcting and may, if desired, include a dimming circuit. The circuitry further includes a runaway protection circuit which is activated upon sensing of a no load condition to place the inverter circuitry in a standby mode of operation.

Abstract: In an electronic ballast for powering three series-connected fluorescent lamps with a 30 kHz lamp current, a half-bridge series-resonance-type inverter circuit is powered from a substantially constant-magnitude DC supply voltage derived from ordinary 60 Hz power line voltage by way of a bridge rectifier and a single-transistor DC-to-DC converter using an energy-storing inductor with an isolated secondary winding from which the DC supply voltage is derived. Thus, the DC supply voltage is electrically isolated from the power line, as is also the inverter circuit itself as well as the ballast's output terminals. Lamp dimming is accomplished via a dimming control directly connected with the inverter circuit.

Abstract: A main power supply device uses single phase, or three phase R, S, T; through rectification and filtration; each phase produces a different D.C. voltage so as to supply a respective voltage transforming device. The rectifier output of a step-down supply of the S, T, phase, in addition to supplying an astable square wave oscillator, so as to control signal outputs via a driving circuit, also supplies a tripping device, so as to control the high A.C. output from the high-voltage transformer of the transforming device. Any abnormal load can be detected by a detecting transformer and a protective circuit, so as to control cut-off of a transistor of a switching loop. A plurality of transforming devices are of the modular plate type; trouble-shooting can be performed easily, and the speed of maintenance is increased; the working safety is also enhanced.

Abstract: A circuit, including an electrical load such as a fluorescent lamp, energized through an inverter which is in turn energized from a standard household alternating current voltage source. The output of the inverter is of a low voltage, low current and high frequency. This power is then transmitted by a low current voltage link, in the form of a flexible small gauge, jacketed wire conductor connected across the outputs of the inverter, to the input terminals of a compact step-up transformer located a distance away from the inverter. The power created by the step-up transformer is converted to usable power by the electrical load. The low voltage link need not be enclosed in a raceway.

Abstract: A neon sign transformer for operating a neon tube from a mains frequency alternating current comprising: a filter for filtering electro-magnetic interference from said alternating current; a first rectifier for rectifying said filtered alternating current so as to produce a low level alternating current; electrical circuit driver for generating a high frequency low level alternating current; an electrical power circuitry for generating a high frequency high level alternating current then rectified to provide said high level direct current for energizing said neon tubes.

Abstract: To shorten the time between firing of a high-pressure discharge lamp and stantial light output therefrom, the discharge lamp includes a fill of xenon, at a cold fill pressure of at least 3 bar, in addition to mercury and a metal halide; the discharge vessel (2) is, at least in part, coated or doped so that invisible radiation is reflected into the lamp, or absorbed, while visible radiation is being transmitted by the discharge vessel. The shafts of the electrodes are thin, of only about 0.3 mm diameter, and the electrodes facing each other are part-spherical or rounded. The lamp is operated in combination with a lamp power supply (S) which has the characteristics of being capable of supplying between 5 to 10 times normal operating current of the lamp under starting conditions.

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

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

Abstract: A high intensity discharge metal vapor lamp comprising an arc tube having an inner chamber vented to the arc tube and disposed therein is disclosed. The combination of the arc tube and inner chamber being of a double wall construction confines the arc condition occurring between thermionic electrodes to be within the inner chamber. The inner chamber is operated at an increased wall temperature, relative to a conventional arc tube, while at the same time reducing the typically experienced sodium losses that normally occur for increased wall temperature operation. Ceramic evaporation at elevated temperatures from the inner chamber can be rendered innocuous by deposition on a similar material utilized in the arc tube. The characteristics of the arc tube allows for improved methods of its operation such as a pulsed operation at a relatively high rate of 1 to 20 KHz so as to achieve a relatively high color temperature. If desired, the arc tube may be operated in a d.c.

Abstract: A series ballast circuit for operating a gas discharge tube from a constant current alternating voltage source having a fundamental frequency is disclosed. The primary feature of the ballast circuit comprises a ballast transformer having a magnetic core and at least a primary coil and at least a secondary coil. The ballast transformer has parameters that are selected in accordance with the operational conditions, that is, the extinguished and non-extinguished states of the gas discharge lamp. The primary coil and the area of the core have parameters selected in accordance with the extinguished state of the gas discharge tube. The primary and secondary coils have a selected turn ratio so as to produce a current level sufficient to maintain the ionization condition of the gas discharge tube in its non-extinguished state.

Abstract: A power supply for a metal halide discharge lamp includes a circuit for applying a high voltage starting pulse to the arc tube of the lamp to initiate the discharge, a glow transition current to provide power transitioning the arc tube from its glow to its run mode, and a run power supply circuit to provide continuous controlled d-c current to the arc tube.

Abstract: A push-pull generator with a driver stage and a push-pull output stage. A parallel connection of a resistor (R3, R4) with a control transistor (T3, T4) is provided in the base line of each output stage transistor. In the push-pull output stage, resistors (R1, R2) are provided at which a voltage drop is caused by the output stage current. Depending on the magnitude of the voltage drop the control transistors (T3, T4) located parallel to the resistors in the base lines are either activated or blocked.

Abstract: An electronic ballast system for operating fluorescent lamps at full and partial brightness is disclosed having a series reactance selectively switched into or out of the system by a reactance switch. The electronic ballast has an input filtering section, a voltage-clamped current source, and an oscillator whose frequency is determined in part by load reactance. Series filament capacitors provide lamp filament power control during starting and running at full and partial brightness.

Abstract: An electronic transformer system for illuminating neon lamps includes a counterphase oscillator coupled to a leakage reactance power transference transformer. The power transference transformer has a secondary wound on a multiple section bobbin in which adjacent sections are separated from each other by a dielectric material. The leakage reactance power transference transformer has a feedback winding which is coupled in series to the primary winding of a pulse generator base driving transformer. The pulse generator base driving transformer in turn provides periodic pulses to the counterphase oscillator to reverse current flow in the primary of the leakage reactance power transference transformer. The electronic transformer system may be powered by commercial alternating current through a full wave rectifier, or by a direct current power supply.

Abstract: A non-saturating, self-driven switching inverter for a gas discharge device is disclosed herein having an inverter transformer including primary and secondary windings coupled respectively to alternately applied power and a pair of switching transistors. A resistive network coupled between the secondary winding and the bases of the switching transistors for conducting power for alternately polarizing the transistors in the ON state or condition. A diode network is connected in parallel with the resistive network to selectively reduce impedance of the secondary winding.

Abstract: A device for starting and operating gas discharge tubes including a DC-to-AC inverter which generates a low voltage or a high voltage at an output thereof in response to first or second input signals, respectively. The output of the inverter is connected to a gas discharge tube and sensing means generates a signal proportional to the current flow through the tube. Suitable means provides a trigger or synchronizing signal to a driver. The driver, responsive to the sensed output signal and the trigger or synchronizing signal, generates a drive signal synchronized with the trigger or synchronizing signal and having a duration inversely related to the magnitude of the current flowing through the gas discharge tube. A high voltage switch applies a second input signal to the inverter in response to the drive signal to provide a decreasing high voltage duration during successive cycles of the inverter as the tube begins to conduct current.

Abstract: A low-voltage system is disclosed for supplying operating power to high-voltage neon light tubes located within housings in the forms of letters and other shapes commonly used for illuminated advertising on the outside of buildings. Within the building, a first step-down transformer is connected to the conventional household power supply of 110 volt 60 Hz current. The step-down transformer produces a low-voltage signal in the range of 16 to 24 volts at the 60 Hz operating frequency. The low-voltage wires are passed through the exterior wall of the building on which the advertising sign housing is mounted and require no special precautions or high-voltage insulation due to the extremely low voltage involved. Within each high-voltage lamp housing, a solid state low-voltage to high-voltage conversion circuit is mounted. The input to this circuit comprises the 16 to 24 volt 60 Hz low-voltage current.

Abstract: A stabilized dimming circuit for an electronic ballast system. The dimming circuit includes a transformer having a variable inductance primary included as a part of a feedback loop comprising a push-pull inverter and an output transformer for supplying a drive signal to a lamp filament. As the inductance of the primary is varied (decreased), the amount of feedback applied to the inverter is varied (increased) and the lamp brightness dimmed accordingly. The secondary of the dimming transformer is included in a loop that is completed by a secondary winding of the output transformer and a lamp filament. Because the voltage induced in the secondary of the dimming transformer is held relatively constant, the voltage applied to the filament is stabilized in spite of varations in the amount of power supplied to the lamp.

Abstract: Unitary light source comprises compact HID lamp and starting and operating circuit therefor operable from household AC energizing potential. The HID lamp is ballasted by incandescent filament means which also provides the major portion of developed light during HID warm up and after power interruption. The ballast filament and input terminals of a full-wave rectifier connect in series across the light source input terminals and the HID lamp connects across the rectifier output. A low-impedance path means and high-voltage pulse generator, which includes a high-voltage electrode operatively associated with the HID lamp, connect across the rectifier input. Initially, the voltage developed across the rectifier input is relatively high and the pulse generator and low-impedance path means are responsive thereto to devleop high voltage pulses and also provide a low impedance path in series with the ballast filament to cause it to incandesce brightly.

Abstract: In order to effect stabilized dimming of a fluorescent lamp, that is, in order to vary the power level supplied the lamp while maintaining a substantially constant filament voltage, a first, variable, inductance is included as an element of oscillator (inverter) feedback loop. The voltage across the variable inductance is clamped and coupled to a second inductance so that a voltage appears across the second inductance in proportion to the voltage appearing across the variable inductance. The voltage appearing across the second inductance is applied to the lamp filament so as to constitute a dominant component of the lamp filament voltage.

Abstract: A power supply for an electric insect trap having an electrocution grid and a fluorescent lamp for attracting insects to the grid employs an inverter to generate a high frequency alternating voltage. The alternating voltage is applied across the primary winding of a first transformer having a secondary winding for development of a current-limited voltage for operating the lamp. Due to large inductance, the secondary winding functions as a constant current source to the lamp, so that lamps having different voltage characteristics may be used in the same circuit. A high voltage transformer has a primary driven by the limited lamp current to produce a high voltage for the electrocution grid across its secondary winding. Current limiting is achieved, in part, by providing a selected amount of flux leakage between the primary and secondary windings of the first transformer.

Abstract: An output configuration for an electronic ballast system includes means for effecting independent selection of both pre- and post-ignition lamp filament voltages. The primary of a filament voltage control transformer is coupled to lamp filaments so as to induce a voltage in the transformer secondary windings in relation to the lamp filament current. The secondary windings are arranged so that the voltage induced therein adds to the voltage provided to the lamp filaments by filament drive windings on the ballast output transformer.

Abstract: An improved output configuration for a multiple-lamp electronic ballast system. The output includes a differential transformer having a primary adapted to be coupled in a first loop including a first filament filament drive winding and feedback winding and a secondary adapted to be coupled in a second loop that includes a second filament, filament drive winding and feedback winding.The improvement allows the entire ballast to be shut down when a lamp has been removed thereby avoiding aberrant oscillator operation under abnormal, yet predictable, lamp load conditions.

Abstract: A dimmer circuit for an inverter-driven electronic ballast system. The ballast includes an output transformer having a primary winding coupled to the inverter output and a secondary winding adapted to be coupled to a lamp filament winding for supplying power to the filament. An interstage transformer has a primary winding adapted to be coupled to a lamp filament and a secondary winding coupled to an inverter input for applying a feedback signal derived from the filament current at that input. The dimmer circuit is in the form of a feedback loop that includes a winding on the primary of the output transformer, a winding on the primary of the interstage transformer, and a variable impedance coupling those windings. Varying the impedance necessarily varies the total feedback loop impedance and therefore the amount of feedback applied at the inverter output and, inversely, the power supplied to the lamp filament.

Abstract: An improved drive scheme for a pair of push-pull inverter transistors in an electronic ballast circuit. The inverter output is coupled through a series resonant circuit comprising a capacitor and the primary winding of an output transformer. The resonant circuit is coupled to the inverter output through an additional winding on the primary of an interstage so that a component of the loop current is fed back to the bases of the push-pull transistors, thereby compensating for phase errors in the drive signal applied at the inverter input.

Abstract: Starting and operating circuit for gaseous discharge lamps has device for quickly re-starting extinguished lamps while still hot. Circuit comprises a source of alternating current, an inductive regulator ballast having its input connected to the alternating current source, and a gaseous discharge lamp connected to the output of the ballast, a sine wave oscillator circuit having its input connected to the current supply and having its output connected to a transformer connected in series between the ballast and the lamp for stepping up and applying voltage to a lamp, the oscillator circuit comprising a transistor switch and an oscillator transformer connected to the step-up transformer for producing a high voltage, high frequency sine wave for starting and re-starting the discharge lamp. The operation of the oscillator circuit is improved by a turn-off circuit comprising series-connected diode and inductor connected to the transistor and the oscillator transformer.

Abstract: A power supply system for operating fluorescent lamps in a hazardous atmosphere comprises a 1 kHz to 500 kHz constant current power supply which feeds primary windings of transformers which are connected together in series. Fluorescent lamps are connected across the transformer secondary windings. A voltage control circuit is connected to the supply supply output to ensure that the amount of electrical energy supplied to the transformers cannot ignite the atmosphere under any normal or fault condition. Capacitors are connected in series with the transformer primary windings to reduce the circuit reactance so that, for a given level of supply voltage, an increased number of lamps can be fed with starting voltage. Due to the substantially constant current which is fed through the transformer primary windings, the situation cannot occur that the firing of one lamp prevents the others from firing. The transformers preferably include windings to feed heaters of the lamps.

Abstract: An electronic ballast circuit includes a directly driven high frequency inverter circuit with a series resonant output circuit coupled to a load circuit having a high intensity discharge (HID) lamp and to a drive circuit dependent upon current flow in the load circuit. A starting circuit for the high frequency inverter is coupled to a DC source and to a charge storage and isolating circuit and provides initial energization to the high frequency inverter circuit. Also, a lamp starting circuit initiates increased conductivity of the high frequency inverter circuit which causes development of energy sufficient to "fire" an HID lamp whereupon a disablement circuit essentially removes the lamp starting circuit from the operational circuitry.

Abstract: An electronic ballast circuit includes a direct drive high frequency inverter circuit with a tuned output circuit and a drive circuit dependent upon current flow in a load circuit. The high frequency inverter circuit is coupled to a DC potential source which is derived from a pulsed DC potential source by way of a charge storage and charge isolating circuit. An oscillator provides a starting capability for the high frequency inverter circuit and is essentially removed from the active circuitry upon energization of the high frequency inverter circuit.

Abstract: A direct drive electronic ballast circuit suitable for a fluorescent lamp load includes a high frequency oscillator inverter circuit having a tuned output circuit coupled to a load and to a drive circuit series connected to the load and dependent upon current flow therein. The high frequency oscillator inverter circuit is also coupled to a pulsed DC potential source which is shunted by a charge storage and isolating circuit energized by a feedback rectifier circuit which supplies energy whenever the potential from the pulsed DC potential source decreases below a given reference level. A relaxation type oscillator is coupled to the high frequency oscillator inverter circuit and provides a starting capability therefore.

Abstract: High efficiency push-pull inverters minimize undesirable energy losses usually resulting from simultaneous conduction and imperfect switching of the transistor switching means. In each of the disclosed circuits, a saturable inductor and a diode are connected in parallel and across the base-emitter junction of each transistor. Voltage on the base of each transistor causes its associated saturable inductor to saturate, and the saturated inductor then terminates the flow of base current and provides a path for rapid evacuation of the charge carriers stored in the transistor base-emitter junction in order to render the transistor rapidly non-conductive. Each diode provides a drain path for current continuing to flow through its associated saturable inductor after junction evacuation. A novel triggering means initiates oscillation of the inverters.

Abstract: A high power factor conversion circuit suitable as a ballast circuit for lamps includes a full-wave rectifier coupled to an AC potential source and providing a pulsating DC potential. A high frequency inverter is coupled to a load circuit and to a feedback rectifier circuit supplying a rectified high frequency potential to an energy storage feedback circuit which provides energy in a manner to inhibit a decline in the pulsating DC potential thereby providing a substantially uniform DC potential to the high frequency inverter.

Abstract: A high frequency transistor ballast is utilized to drive flourescent lamps. The electrical system of the ballast consists of a central rectifying and control panel and a high frequency inverter. There is also provided a low energy switch in the high frequency inverter system controlling the operation of the high frequency transistor ballast.

Abstract: High efficiency push-pull inverters minimize undesirable energy losses usually resulting from simultaneous conduction and imperfect switching of the transistor switching means. In each of the disclosed circuits, a saturable inductor and a diode are connected in parallel and across the base-emitter junction of each transistor. Voltage on the base of each transistor causes its associated saturable inductor to saturate, and the saturated inductor then terminates the flow of base current and provides a path for rapid evacuation of the charge carriers stored in the transistor base-emitter junction in order to render the transistor rapidly non-conductive. Each diode provides a drain path for current continuing to flow through its associated saturable inductor after junction evacuation. A novel triggering means initiates oscillation of the inverters.