U.S. Philips Corporation

Philips Electronics North America Corporation

Ronald Siepkes

Yongping Xia

Hubertus M Chermin

Richard Qun Li

John Wei-Fan Chou

A circuit arrangement for igniting and supplying a discharge lamp by means of a substantially square-wave voltage at a frequency f1. It is possible to dim the lamp by adjusting the frequency of the substantially square-wave voltage to a value f2 which is different from f1. A protection circuit prevents damage to the lamp and to the circuit arrangement if the lamp current does not flow any more at the frequency f2.

Circuit arrangement for ingniting and supplying power to a lamp

A lighting control circuit that controls the lighting of particular lamps in response to the toggling of the power switch. The circuit a) connects only with the high (output) side of a lighting system's ballast, b) is completely contained on the high side, and c) with regard to toggling, is dependent upon only a single time period. The circuit can be used with any ballast which makes use of an output transformer and no change need be made to the original ballast circuitry. Users will find operation of the circuit to be straightforward. A triac driven by a flip-flop via a driver transistor is used to control the high frequency AC power that is used to drive the lamps. A Schmitt trigger sharpens the signal generated by the ballast output transformer in response to the toggling of the light switch which is employed to change the output state of the flip-flop. Operationally, all the lamps driven by the ballast are lit when the power switch is initially turned on. Toggling the power switch once while all of the lamps are lit causes only a predetermined number of the lamps to remain lit. Toggling the power switch while only a portion of the lamps are lit causes all of the lamps to light again. Leaving the power switch off causes all of the lamps to be turned off. The toggling may be performed quickly or leisurely, so long as the entire toggle cycle is completed within a predetermined amount of time.

Lighting control for reducing energy consumption

A circuit arrangement for preheating electrodes of a discharge lamp connected in series with a ballast by means of a supply voltage of alternating polarity. The circuit arrangement is provided with a switching element (S) which shunts the lamp and which is operated by means of a control signal. A circuit portion (II) adjusts both the phase and the frequency of the control signal in dependence on whether the ballast is inductive or capacitive. The electrodes of the lamp are preheated in a short period both for an inductive ballast and for a capacitive ballast.

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Eindhoven, Netherlands

Ronald Siepkes