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High pressure discharge lamp

IP.com Disclosure Number: IPCOM000011605D
Publication Date: 2003-Mar-10
Document File: 1 page(s) / 52K

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The IP.com Prior Art Database



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High pressure discharge lamp

A high pressure discharge lamp having a discharge vessel with a ceramic wall, for instance polycrystalline alumina (PCA) wherein an ionizable filling comprising metal halide is provided with a niobium conductor as an feedtrough conductor to an electrode inside the discharge vessel. The niobium conductor is sealed to an extended plug forming part of the ceramic wall in a gas tight manner with a frit.

The process for melting the frit between the niobium conductor and the PCA extended plug (VUP) requires a blackening of the VUP. A coating increases the absorption in the infrared and enables more energy to be delivered to the VUP locally in the heating process of making the seal. Localized heating during the sealing process is of importance for a high lamp manufacture yielding.

Change of the infrared absorption property of the VUP by the applied coating will also modify the infrared emission once the lamp is in operation. With a higher infrared emission, the VUP will operate at a lower temperature. This can be advantageously used by extending the coating over the full length of the VUP and over part of the discharge vessel up to at the most about the electrode. The resulting increased infrared emission during operation will allow operating the lamp at a higher power without exceeding the maximum permissible wall temperature.

It is thus advantageous that one half of the VUP is coated before the sealing process is started (fig 1) as to improve manufact...