| 摘要 |
PROBLEM TO BE SOLVED: To improve starting property, light flux, and the life of a discharge lamp by controlling a high frequency electromagnetic field generated by an induction coil installed in a discharge gas-sealed bulb. SOLUTION: In an electrodeless low pressure discharge lamp 1, a phosphor 9 is applied to a discharge space inner wall inside a discharge gas-sealed and light tramsmissive material-made bulb 1, high frequency power flows from a lighting circuit 8 into a matching circuit 6 in a space 5 through a cable 7, the high frequency power is applied to an induction coil 2 from the matching circuit 6 so as to generate a high frequency electromagnetic field to cause discharge gas to exciting emit light, and the phosphor 9 emits light. The induction coil 2 is provided in the hollow (k) of the bulb 1, and a metal cylindrical body 3 which has an opening on a deep side of the hollow (k) of the bulb 1 having the same potential with the earth side of a high frequency lighting device and has excellent thermal conductivity is inserted between the bulb 1 and the induction coil 2. A slit 3a which is in a nearly vertical direction to the winding direction of the induction coil 2 is provided in the metal cylindrical body 3. |
