Light source device, and sterilizing/deodorizing device

A sterilizing/deodorizing device comprising:

• an excimer lamp that emits ultraviolet light by dielectric-barrier discharge;
• a flyback-type lighting device that supplies power to the excimer lamp;
• a switching element equipped in the lighting device;
• a transformer to which the switching element is connected on the primary side and the excimer lamp is connected on the secondary side, the transformer being equipped in the lighting device;
• and
• a control circuit that supplies a drive signal to the switching element and that is equipped in the lighting device;
• wherein
• the control circuit controls the switching element on and off with the switching frequency fixed to the frequency FS and with the ON duty fixed to the ON duty TS for a predetermined time during the time of starting to light the excimer lamp,
• after the predetermined time elapsed, the control circuit controls the switching element on and off with the switching frequency increased from the frequency FS and the ON duty increased from the ON duty TS, and
• the control circuit controls the switching element on and off with the switching frequency fixed to the frequency FO higher than the frequency FS and with the ON duty fixed to the ON duty TO higher than the ON duty TS during the time of steady-state lighting of the excimer lamp.