ELECTRODE-LESS DISCHARGE LAMP

摘要

PURPOSE:To provide an electrode-less discharge lamp which can be easily started. CONSTITUTION:A bulb 1 is made of a light transmission material and is formed into a spherical configuration and a discharge gas is sealed in the interior thereof. An induction coil 2 to which a high frequency current is supplied from a high frequency power source 4 is wound around the bulb 1. An auxiliary electrode 3 which permits application of a high frequency voltage between itself and a ground is disposed around an outer peripheral surface of the bulb 1 so as to be electrostatically coupled to an internal space of the bulb 1. Within the bulb 1, a regulation wall 6 which opposes the auxiliary electrode 3 is disposed. The regulation wall 6 is provided with a recess portion 6a which is open toward the opposing auxiliary electrode 3. When a high frequency voltage is applied to the auxiliary electrode 3 with resultant occurrence of a preliminary discharge, a fore end of a discharge path of the preliminary discharge is extended into the recess portion 6a. Upon subsequent supply of a high frequency current to the induction coil 2, the discharge transmits to an annular discharge along the inside surface of the recess portion 6a.