Patent ID: 6888311
Filing Date: 2005-05-03
Classification: H01J

Abstract:
1. Ultrahigh pressure mercury lamp, comprising: a discharge vessel having a bulb part of translucent material in essentially the shape of an ovoid and side tube parts which extend along a tube axis from opposite sides of the bulb part, the discharge vessel being filled with at least 0.2 mg/mm opposed anode and cathode electrodes disposed in the discharge vessel; wherein the anode has a tip area and rear end, the tip area having a larger diameter than the rear end, and part of the tip area is located in a respective one of the side tube parts; wherein the lamp is adapted for operation at an input wattage of at most 400 W using direct current, and wherein the length D (mm) of a tip area of the anode and a length L (mm) of the bulb part in a direction of the tube axis of the lamp is set in accordance with the relationship D≧L/2.