Thick film resistor for use in a vacuum and a high pressure discharge lamp having such a resistor

摘要

A high pressure discharge lamp having a thick film resistor comprising a plurality of resistive elements. A first resistive element is included in a starting circuit for the lamp and a second resistive element is in series with the arc tube during lamp operation for flicker elimination. The integral thick film resistor facilitates mounting and connection of the resistor elements within the lamp envelope. Favorably, the resistor substrate has a surface emissivity of greater than about 0.5, and preferably greater than about 0.9, to provide sufficient radiation cooling within an evacuated outer lamp envelope to prevent resistor failure while keeping the size of the resistor small enough for use as a component in an HID lamp. Additionally, a suitable coating of low vapor pressure thickness covers the solder connecting the metallic resistor terminals to the substrate to prevent evaporation of the solder and its deposition on the inner surface of the outer lamp envelope.