Discharge lamp driver, light source apparatus, projector, and discharge lamp driving method

A discharge lamp driver comprising:

• a discharge lamp driving section configured to supply drive current to a discharge lamp including a first electrode and a second electrode;
• and
• a control section configured to control the discharge lamp driving section,
• wherein the control section is configured to alternately repeat a first period in which an AC current is supplied to the discharge lamp and a second period in which a DC current is supplied to the discharge lamp, and
• wherein in a case where a first drive power lower than a rated power of the discharge lamp is supplied to the discharge lamp and an accumulated lighting time of the discharge lamp is shorter than a predetermined time, the control section is configured to
• set a length of the first period to be greater than the length of the first period in a case where the first drive power is supplied to the discharge lamp and the accumulated lighting time is equal to or longer than the predetermined time, and
• set a frequency of the AC current during the first period to be higher than the frequency of the AC current during the first period in the case where the first drive power is supplied to the discharge lamp and the accumulated lighting time is equal to or longer than the predetermined time.