Patent ID: 6548965
Filing Date: 2003-04-15
Classification: H01J,H05B

Abstract:
An electrodeless fluorescent lamp comprising:a glass lamp envelope made from a single straight tube, said envelope having an outer surface and an axis of symmetry; at least one reentrant cavity disposed within said envelope and aligned with said axis of symmetry, said cavity being sealed to said envelope; a filling of inert gas and at least one vaporous metal selected from the group consisting of mercury, cadmium, sodium the vapor pressure of said metal being below 10 mTorr during operation; a protective coating disposed on the inner surface of said envelope and said cavity; a phosphor coating disposed on said protective coating; a reflective coating disposed on inner surface of said cavity between said protective coating and said phosphor coating; an inductive coil formed of a plurality of windings disposed on said outer surface of said envelope, said windings being wrapped around said envelope in a direction that is parallel to said axis of symmetry, thereby forming the closed-loop discharge inside said envelope, a radio-frequency (RF) power source coupled to said coil to ignite and maintain RF discharge in said envelope to generate a plasma.