Discharge lamp driving device, light source device, projector, and discharge lamp driving method

A discharge lamp driving device comprising:

• a discharge lamp driving unit that supplies a driving current for driving a discharge lamp to the discharge lamp;
• and
• a control unit that controls the discharge lamp driving unit,
• wherein the control unit controls the discharge lamp driving unit such that the driving current having driving periods is supplied to the discharge lamp, the driving period including:
• a mixing period which alternately has an AC period in which an alternating current is supplied to the discharge lamp and a first DC period in which a direct current is supplied to the discharge lamp and
• a second DC period which is provided immediately after the mixing period and in which a direct current having a polarity which is opposite to that of the direct current in the first DC period is supplied to the discharge lamp, and
• the length of the first DC period is shorter than the length of the AC period, longer than the length of a half cycle of the alternating current in the AC period, shorter than the length of the second DC period, and equal to or greater than 0.5 ms and equal to or less than 7.0 ms.