Patent ID: 8342695

Claim:
A high pressure discharge lamp lighting apparatus, comprising: a high pressure discharge lamp comprising: a silica glass electric discharge container enclosing a first electrode arranged to face a second electrode at an interval of 2 mm or less, and 0.15 mg/mm 3 or more of mercury, rare gas, and halogen in a range of 10 −6 μmol/mm 3 to 10 −2 μmol/mm 3 ; and a power supply apparatus that supplies a rectangle wave alternating current to the high pressure discharge lamp, wherein the high pressure discharge lamp has a steady power lighting mode and a low power lighting mode, wherein the discharge lamp is driven by an alternating current in the steady power lighting mode in which a first polarity and a second polarity are repeated by turns at a regular electric power lighting frequency selected from a range of 100 Hz-5 kHz, wherein the high pressure discharge lamp is driven at 50% or less of the alternating current in the low power lighting mode, wherein the alternating current comprises a first time unit and a second time unit that are repeated by turns so as to drive the discharge lamp, wherein the first time unit has a time width t 1 and has one of the first and the second polarities, and wherein the second time unit has a time width t 2 and the first polarity and the second polarity are repeated by turns five times or more at intervals of the time width t 2 .