Patent ID: 7439691

Claim:
High pressure discharge lamp lighting device comprising: a high pressure discharge lamp having a pair of electrodes that have massive portions with tips that face each other across a gap of no more than 2.0 mm within a light emitting part in which are sealed at least 0.20 mg/mm 3 of mercury and a halogen in the range of 10 −6 μmol/mm 3 to 10 −2 μmol/mm 3 , and a power supply device that is adapted to feed alternating current to the discharge lamp of different current values, wherein the power supply device feeds the alternating current to the discharge lamp in a manner such that a constant current control period (Ti) from initial discharge until a transition to a constant power control period (Tw) has a first control period (T 1 ) until the diameter of the discharge arc begins to be constricted and a second control period (T 2 ) from the point when the diameter of the discharge arc begins to be constricted until transition to the constant power control period (Tw), wherein the power supply device is adapted to feed a current to the high pressure discharge lamp during the first control period (T 1 ) that has a first value (I 1 ) which is greater than a maximum current value (Itw-max) fed during the constant power control period (Tw), and wherein the power supply device is adapted to feed a current to the high pressure discharge lamp that has a second value (I 2 ) during the second control period that is less than the maximum current value (Itw-max) fed during the constant power control period (Tw).