Compact fluorescent light source having metallized electrodes

Abstract

Light source wherein high frequency power is capacitively coupled to a low pressure discharge includes at least one metallized power coupling conductor. A discharge lamp includes an envelope which is typically pear-shaped with a re-entrant cavity. The lamp envelope encloses a fill material which forms during discharge a plasma which emits ultravoilet radiation and typically includes on its inner surface a phosphor coating. An outer conductor is disposed around the outer surface of the lamp envelope. A conductive coating disposed on the inner surface of the re-entrant cavity forms the inner conductor. The outer conductor can be a conductive mesh or can be a conductive coating disposed on the outer surface of the lamp envelope in a pattern which permits light to escape from the lamp. When the conductive coating of the inner conductor is substantially more than one skin depth in thickness at the frequency of operation, the re-entrant cavity is substantially field-free and can be used to house power source circuitry. When the conductive coating of the outer conductor is substantially more than one skin depth in thickness at the frequency of operation, the light source is prevented from radiating high frequency power. A high frequency power source can be included in the light source.