U.S. Philips Corporation

Rudolf L Van Der Heijden

Jan Willem Dorleijn

Jan W Denneman

A method of and a device for the operation of a high-pressure discharger lamp provided with a discharge vessel (3) which accommodates an ionizable filling and two electrodes (4, 5), between which electrodes in the operating condition the discharge takes place. The lamp is operated from a supply source which supplies a power of periodically alternating value. According to the invention, for each power frequency .nu..sub.i (i=1,2, . . .) the relation .nu..sub.i .gtoreq.60 .nu..sub.1 is satisfied, where .nu..sub.1 is the lowest frequency at which in the operating condition of the lamp standing pressure waves can occur in the discharge vessel (3). Thus, it is possible to operate the lamp so as to be free from arc instabilities due to standing pressure waves.

Method of operating a high-pressure discharge lamp

The invention relates to a high-pressure sodium lamp provided with an elongate discharge vessel in which the pressure P in the operative condition of the lamp is at least 170.times.10.sup.3 Pa. The lamp is suitable to be operated with a power of periodically alternating value, which power comprises at least one component having a frequency .nu..sub.i which satisfies i-0.45.ltoreq.2.35.nu..sub.i Le/e.ltoreq.i+0.45 where i is an integral positive number, c is the speed of sound in the gaseous part of the filling and L.sub.e is the effective length of the discharge vessel. According to the invention, the relation is satisfied: M.nu..sub.i .multidot.f.sub.i .multidot.P.multidot.d .ltoreq.185, in which M.nu..sub.i is the modulation depth of the power component having a frequency .nu..sub.i, f.sub.i is a geometric lamp factor and d the average inner diameter of the discharge vessel. In this manner, the operation of the lamp is free of arc instabilities due to longitudinal acoustic resonances.

Growing community of inventors

Eindhoven, Netherlands

Rudolf L Van Der Heijden