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

A discharge lamp driving device comprising:

• a discharge lamp driving section configured to supply a driving current to a discharge lamp;
• a control section configured to control the discharge lamp driving section;
• and
• a voltage detecting section configured to detect an interelectrode voltage of the discharge lamp, wherein
• the control section is configured to execute a first discharge lamp driving for executing a first control and a second control for supplying the driving current including a direct current and an alternating current to the discharge lamp,
• in the first discharge lamp driving, the control section executes the first control when the interelectrode voltage is equal to or smaller than a first threshold voltage at predetermined setting timing and executes the second control when the interelectrode voltage is larger than the first threshold voltage at the predetermined setting timing, and
• a rate of the direct current in the second control is larger than a rate of the direct current in the first control, wherein
• the alternating current in the first control includes a first alternating current having a first frequency and a second alternating current having a second frequency lower than the first frequency,
• the control section adjusts a rate of the first alternating current and a rate of the second alternating current on the basis of the first threshold voltage, and
• the control section sets the rate of the second alternating current larger than the rate of the first alternating current when the first threshold voltage is equal to or smaller than a predetermined value and sets the rate of the first alternating current larger than the rate of the second alternating current when the first threshold voltage is larger than the predetermined value.