U.S. Philips Corporation

Monique M Eerdekens

Robertus A Keijser

Johannes T De Hair

Johannes H Van Der Sande

The invention relates to a high-pressure sodium discharge lamp provided with a discharge vessel having a ceramic wall and enclosed with intervening space by an outer bulb. The discharge vessel is provided with two electrodes whose respective tips have a mutual distance D. The discharge vessel has a substantially circular cross-section with an interior diameter d.sub.i over the distance D. Under nominal operating conditions, according to the invention, the wall has a wall load of at least 60 W/cm.sup.2, the space between the outer bulb and the discharge vessel contains a gas filling, and D/d.sub.i being &gt;6.

High-pressure sodium discharge lamp

The invention relates to a high-pressure sodium discharge lamp which under nominal operating conditions radiates white light with a maximum color rendering index R.sub.a of more than 80. Since the wall load is above 80 W/cm.sup.2 under nominal operating conditions, a color temperature T.sub.c of at least 2800.degree. K. can be achieved with a luminous efficacy of more than 40 lm/W.

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Eindhoven, Netherlands

Monique M Eerdekens