Patent ID: 8042953

Claim:
A projector comprising: plural high-pressure discharge lamps; a high-pressure discharge lamp lighting device that lights the plural high-pressure discharge lamps; a light combining system that combines and outputs lights from the plural high-pressure discharge lamps; an electro-optical modulation device that modulates the light from the light combining system according to image information; and a projection system that projects the light modulated by the electro-optical modulation device, the high-pressure discharge lamp lighting device supplying alternating lamp currents having alternating-current waveforms with the same waveform and period and phases shifted by a predetermined amount with respect to each of the high-pressure discharge lamps to the respective plural high-pressure discharge lamps; the high-pressure discharge lamp lighting device having: plural ballasts respectively corresponding to the plural high-pressure discharge lamps; and a control circuit that integrally controls the plural ballasts to supply alternating lamp currents having the alternating-current waveforms to the respective plural high-pressure discharge lamps; the high-pressure discharge lamp lighting device being configured to detect rises of the alternating lamp currents and control the plural ballasts based on detection information on the rises of the alternating lamp currents.