Koninklijke Philips Corporation N.v.

Bernd Prokesch

Michael Haacke

A discharge lamp comprises a discharge vesseldefining a sealed inner discharge spacewith two electrodes. A filling consists of a rare gas and a metal halide composition and is free of mercury. The discharge vesselcomprises outer grooveswhere the electrodesare embedded, arranged at a groove distance Ra between them. The discharge vesselfurther comprises an inner diameter ID. In operation of the lamp, an arc discharge is formed between the electrodes and the metal halide composition is partly evaporated. After operation of the lamp, the metal halide composition forms a film on the inner wall of the discharge vessel. This film has a surface area Ameasured in mm. The metal halide composition is provided in such an amount within the discharge space, that a matching quotient Q, calculated as Q=Ra&#xd7;ID/Ahas a value of 2 or more, such that a high color temperature is achieved.

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Cologne, Germany

Bernd Prokesch