MICROWAVE ELECTRIC-DISCHARGE LIGHT SOURCE DEVICE

PURPOSE:To reduce the leakage of microwaves by driving the microwave- producing source of a microwave electric-discharge light source device having a single-mode cavity resonance with a decreased electric input for a given time from the time of starting of the device. CONSTITUTION:Microwave radiated by a magnetron 1 is introduced into a rotationally symmetrical cavity through a waveguide 4 to develop a magnetic field, by which an electric discharge lamp 6 is excited and caused to emit light. Capacitors C3 and C4 are connected to or disconnected from capacitors C1 and C2 by controlling contacts TS1 and TS2 by providing a timer TM in a circuit for driving the magnetron 1. Therefore input which is to be fed to the magnetron 1 can be reduced by leaving the contacts TS1 and TS2 open for a given time in starting the device. As a result, the leakage of microwave energy caused due to the mismatching of the impedance of the cavity 4 before burning is reduced, thereby enabling the safety of the device to be increased.