High pressure discharge lamp lighting device, projector provided with the same, and high pressure discharge lamp lighting method

A high pressure discharge lamp lighting device for lighting, by supply of an electric current, a high pressure discharge lamp including a glass bulb with a halogen substance sealed therein and with a pair of electrodes positioned therein in opposing positions to one another, the high pressure discharge lamp lighting device comprising:

• a polarity inverting unit configured to invert polarity of the current to be supplied to the high pressure discharge lamp;
• a current modifying unit configured to modify an absolute value of the current;
• and
• a control unit configured to control the polarity inverting unit and the current modifying unit, wherein
• the control unit controls the polarity inverting unit to repeat a first period and a second period,
• the first period continuing for at least two cycles, each cycle including a first sub-period during which the current is maintained in one polarity, and a second sub-period during which the current is maintained in an opposite polarity to the one polarity, the second sub-period being shorter than and subsequent to the first sub-period, and
• the second period, during which the current is maintained in a constant polarity, being as long as or longer than the first sub-period, and
• the control unit controls the current modifying unit to maintain the absolute value of the current at a first current value during at least part of the first period, and maintain the absolute value of the current at a second current value, greater than the first current value, during the second period.

A high pressure discharge lamp lighting method for lighting, by supply of an electric current, a high pressure discharge lamp including a glass bulb with a halogen substance sealed therein and with a pair of electrodes positioned therein in opposing positions to one another, the high pressure discharge lamp lighting method comprising:

• repeating a first period and a second period, wherein
• the first period continues for at least two cycles, each cycle including a first sub-period during which the current is maintained in one polarity, and a second sub-period during which the current is maintained in an opposite polarity to the one polarity, the second sub-period being shorter than and subsequent to the first sub-period, and
• the second period, during which the current is maintained in a constant polarity, is as long as or longer than the first sub-period, and
• maintaining the absolute value of the current at a first current value during at least part of the first period and at a second current value, greater than the first current value, during the second period.