Circuits, and methods of using the same, are disclosed for controlling the power supplied to a discharge lamp of the type having a closed inductive loop, such as the resonant ballast circuit for a fluorescent lamp or the inductive ballast loop of a high pressure sodium lamp, wherein the closed inductive loop is operated by an electrical power supply having a d-c input stage and an output power controlled by the switching frequency of a switch means within the power supply itself whereby current flows to the closed inductive loop when the switch means is conductive and no current flows from the power supply to the closed loop when the switch means is non-conductive. This power control circuit comprises means for sensing the instantaneous current flowing through the switch means itself, means controlled by this instantaneous current for creating a first signal with a value that is proportional to the actual power being supplied by the power supply to the closed loop, means for creating a second signal with a value proportional to the desired set point power for the lamp, means for creating an error signal having a value indicative of the difference between the first and second signals, and means for adjusting the switching frequency of the switch means in accordance with the value of the error signal, whereby the output power of the power supply is continuously adjusted toward the set point power for controlling the power actually supplied to the lamp circuit irrespective of the parameters of the lamp circuit itself. The disclosed circuits provide for constant power to a high pressure discharge lamp to yield a constant color temperature. Further, the disclosed circuits provide for dimming of the discharge lamp to selective power levels.

Power control circuit for discharge lamp and method of operating same

controller for a gas discharge lamp 18 supplies the lamp with a direct current which has been pulse-width modulated at a high frequency at switch 24, smoothed and passed through a polarity inversion circuit 14. The polarity inversion circuit periodically reverses the polarity of current supplied to the lamp to equalize electrode wear in the lamp 18. The controller senses the lamp voltage, current, power or other characteristics and maintains at least one operating parameter of the lamp, for example the lamp current, constant. A warm up cycle allows this parameter to be adjusted for fast starting of the lamp.

Controller for gas discharge lamps

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.

Ballast circuit for fluorescent lamp

A method and apparatus for operating at least one gas discharge lamp includes supplying a gas discharge lamp with high-frequency alternating voltage from an externally controlled lamp generator having an operating frequency being variable for dimming the gas discharge lamp. The state of the gas discharge lamp is monitored. A preheating phase with an ensuing starting phase are provided for firing the gas discharge lamp. The operating frequency of the lamp generator during the preheating phase is adjusted to be greater than a rated frequency in rated operation. The operating frequency at the beginning of the starting phase is reduced until the gas discharge lamp has attained a predetermined state and the operating frequency is subsequently maintained at least at an instantaneous value thereof until the gas discharge lamp fires. The operating frequency at the end of the starting phase is reduced to the rated frequency, thereby initiating rated operation. The operating frequency is varied for dimming in an ensuing dimming operation.

Method and apparatus for operating at least one gas discharge lamp

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. The ballast circuit also includes a voltage feedback element in electrical series with the lamp for generating a selected high frequency voltage signal and for applying this signal to the rectification stage. The feedback element superimposes the ballast circuit high frequency voltage signal over the input voltage.

Ballast circuit for compact fluorescent lamp

In a method of operating a gas-discharge lamp, particularly a fluorescent lamp, a radio-frequency a.c. voltage is generated from a d.c. voltage (UE) with the aid of a semiconductor chopper formed from transistors (4, 8), which a.c. voltage is fed into a series resonance circuit. The series resonance circuit consists of a capacitor (13) and an inductor (12) connected in parallel with the discharge path of the lamp (16). The frequency of the a.c. voltage is selected such that before the ignition of the lamp (16) it is higher, and after the ignition of the lamp (16), in normal operation, it is lower, than the resonance frequency of the undamped series resonance circuit consisting of the inductor (12), and the capacitor (13), the frequency separation being selected to be so great that the oscillator current during the ignition phase is at most three times as great as the normal operation current.

Method of operating a gas-discharge lamp

Bei einem Verfahren zum Betreiben einer Gasentladungslampe, insbesondere Leuchtstofflampe, wird mit Hilfe eines aus Transistoren (4, 8) gebildeten Halbleiterzerhackers aus einer Gleichspannung (U E ) ein hochfrequente Wechselspannung erzeugt, die in einen Serienresonanzkreis eingespeist wird Der Serienresonanzkreis besteht aus einem parallel zur Entladungsstrecke der Lampe (16) geschalteten Kondensator (13) und einer Drossel (12) Die Frequenz der Wechselspannung wird derart gewahlt, das sie vor dem Zunden der Lampe (16) hoher und nach dem Zunden der Lampe (16) im Nennbetrieb niedriger als die Resonanzfrequenz des ungedampften, aus der Drossel (12) und dem Kondensator (13) gebildeten Serienresonanzkreises ist, wobei der Frequenzabstand so gros gewahlt wird, das der Schwingkreisstrom wahrend der Zundphase hochstens dreimal so hoch wie der Nennbetriebsstrom ist

Ali-Ihsan Söylemez

Papers

Method of operating a gas-discharge lamp

Verfahren zum Betreiben einer Gasentladungslampe