Light source device, image display apparatus, and method of generating time-division color-separated light

An image display apparatus comprising:

• a discharge lamp provided with two electrodes, and adapted to emit light for display;
• a discharge lamp lighting section adapted to light the discharge lamp by supplying the discharge lamp with electrical power while alternately switching a polarity of one of the electrodes of the discharge lamp with respect to the other of the electrodes;
• and
• a time-division color separation section adapted to receive light emitted from the discharge lamp in a lighted state and sequentially emit light beams with colors different from each other,
• wherein the discharge lamp lighting section switches the polarity in sync with a change in the color of the light beam emitted from the time-division color separation section, retains a duty ratio, which is a ratio of a positive polarity period with the polarity kept positive to a period of the polarity switching, at a constant value during a first retentive period, and retains the duty ratio at a different constant value from the duty ratio in the first retentive period during a second retentive period, thereby modulating the duty ratio.

A method of sequentially generating time-division color-separated light beams with colors different from each other, comprising:

• providing a discharge lamp having two electrodes;
• sequentially generating light beams with colors different from each other while receiving light emitted from the discharge lamp lighted by supplying the discharge lamp with electrical power;
• alternately switching a polarity of one of the electrodes of the discharge lamp to the other of the electrodes in sync with a change in the color of the light beam generated, upon supplying the discharge lamp with the electrical power;
• retaining a duty ratio, which is a ratio of a positive polarity period with the polarity kept positive to a period of the polarity switching, at a constant value during a first retentive period, and
• retaining the duty ratio at a different constant value from the duty ratio in the first retentive period during a second retentive period.