PURPOSE: To restrict a starting high voltage pulse of a discharge lamp lower than dielectric breakdown voltage and facilitate readily starting of the lamp by connecting a voltage absorbing element for absorbing high voltage pulse higher than predetermined level as compared with necessary starting voltage electrically in parallel with a light emitting tube.
CONSTITUTION: A negative resistance element 15 is arranged as voltage absorbing element within the outer tube 11 of a discharge lamp started by high voltage pulse, and connected electrically in parallel with both electrodes. The element 15 has 4,000 volts of maximum voltage value, and 500 volts of maintenance voltage. If high voltage pulse generated upon opening of a bimetal 6 due to energization of a filament 7 exceeds 4,000 volts, it is absorbed by the element 15. Thus, the voltage level of the starting pulse is restricted to less than the voltage breakdown value at the respective components to increase the pulse generating number in the probability corresponding to the area of the portion surrounded by characteristic curves a1Wa3 shown to thereby facilitate readily starting of the lamp.
UEDA MAKOTO
AZUMA TADATOSHI
