High pressure discharge lamp
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsMichihiro Tsuchihashi, Ryo Suzuki, Masato Saito, Heiji Watanabe
Life of this patent
Estimating the term…
Abstract
A high pressure discharge lamp in which the restriking voltage and time are significantly decreased. A pair of electrodes are sealably disposed in a tube containing an appropriate amount of mercury. Means is provided for heating at least one of the electrodes for starting the lamp if it has been recently turned off and the mercury vapor pressure inside the tube is high. The heating means is preferably a filament made of a thermally stable material. One terminal of the filament may be connected to one of the electrodes.
Claims43
In a method for operating a high pressure discharge lamp comprising a transparent tube in which at least mercury is sealed and in which the quantity of mercury in said tube if sufficient to provide a vapor pressure of mercury in said lamp of at least 100 Torr immediately as said lamp has been switched off after operating in a steady state and is still hot, and a pair of electrodes disposed in said tube, the improvement comprising, heating at least of said electrodes for re-starting said lamp at least when said lamp is hot.
A high pressure discharge lamp comprising:
- a transparent tube in which at least mercury is sealed, the amount of mercury sealed in said tube being such that the vapor pressure of mercury in said lamp is at least 100 Torr immediately after said lamp is placed in the off state after reaching a stable operating temperature in the on state;
- a pair of main electrodes disposed confronting one another in said tube;
- and means for heating at least one of said electrodes for starting said lamp immediately after said lamp is placed in the off state after reaching a stable operating temperature in the on state, said heating means being provided closely adjacent said at least one of said electrodes.
Dependencies are inferred from the claim text.