Discharge lamp lighting apparatus

A discharge lamp lighting apparatus comprising:

• a discharge lamp having a pair of electrodes formed of tungsten and having projections at distal ends thereof;
• and
• a power supply apparatus configured to supply AC power to the discharge lamp to light the discharge lamp,
• wherein:
• the power supply apparatus is switchable between a first lighting mode in which rated power is supplied to the discharge lamp and a second lighting mode in which power lower than the rated power is supplied to the discharge lamp,
• the power supply apparatus is configured to supply AC power having a power waveform in which a low-frequency component has a frequency lower than a basic frequency component, low-frequency component being in a range from 60 to 1000 Hz and being cyclically inserted into the basic frequency component supplied to the discharge lamp, and
• the power supply apparatus is configured to control power supplied to the discharge lamp with an average power change ratio of 0.01 to 2.1 W/s in a mode switching period in which the mode is switched from the first lighting mode to the second lighting mode.

A discharge lamp lighting apparatus comprising:

• a discharge lamp having a pair of electrodes formed with projections at distal ends thereof;
• and
• a power supply apparatus configured to supply AC power to the discharge lamp to light the discharge lamp,
• wherein
• the power supply apparatus has a switching the mode for switching between a first lighting mode in which rated power is supplied to the discharge lamp and a second lighting mode in which power lower than the rated power is supplied to the discharge lamp, and is configured to control the power to be supplied to the discharge lamp under the condition that a power value is lowered from a given power value P1 equal to or lower than the supply power in the first lighting mode and equal to or higher than the supply power in the second lighting mode to a power value P2 lower than the power value P1, and then is increased from the power value P2 to a power value P3 higher than the power value P2 and lower than the power value P1 in a mode switching period in which the lighting mode is switched from the first lighting mode to the second lighting mode.

A discharge lamp lighting apparatus comprising:

• a discharge lamp;
• and
• a power supply apparatus configured to supply AC power to the discharge lamp to light the discharge lamp,
• wherein
• the power supply apparatus is configured for switching between a rated power lighting mode in which rated power is supplied to the discharge lamp and a low power lighting mode in which power lower than the rated power is supplied to the discharge lamp, and is configured to supply basic AC power having a predetermined power value continuously to the discharge lamp, and to cyclically superimpose a superimposed power on the basic AC power and simultaneously control supply timing of the superimposed power, the power value of the superimposed power, or the supply time of the superimposed power according to a measured value of lighting voltage of the discharge lamp in the low power lighting mode.