U.S. Philips Corporation

Nicolaas H Reijnders

Meerten Luursema

Machiel A Hendrix

Johannes A Scheepers

A circuit arrangement for operating a high-pressure discharge lamp such that the high-pressure discharge lamp supplies a luminous flux of at least 60% of the nominal luminous flux within 1 s after ignition. The circuit arrangement is made up of a static converter for generating a DC voltage, a commutator provided with lamp connection terminals, a circuit for current stabilization during stable lamp operation by control of the static converter, and a circuit responsive to an instantaneous lamp voltage signal for operating the lamp with an increased run-up current and an increased power as compared with nominal rated operation during a lamp run-up period. A further circuit is provided so that the operation at the increased power includes at least a portion of the lamp run-up period for transition to normal operation. During this portion the increased power has a falling characteristic with a time constant that is independent of lamp voltage.

Discharge lamp power control circuit with reduced light fluctuations

A circuit arrangement for operating a high-pressure sodium lamp is provided with two lamp connection points. The circuit arrangement comprises a controlled main switching element, a control electrode of which is connected to a control circuit. The circuit arrangement is provided with a measuring impedance in series with a lamp connection point and with a measuring impedance parallel to the lamp connection points. The measuring impedances are connected to the control circuit. A combination of a resistor and a capacitor is further connected to the control circuit and this combination is connected in series with one lamp connection point.

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Eindhoven, Netherlands

Nicolaas H Reijnders