Patent ID: 8459802

Claim:
A high-pressure discharge lamp lighting device for lighting, by supplying an alternating current, a high-pressure discharge lamp provided with an arc tube filled with a halogen material and including electrodes disposed therein with protrusions being formed on tips of the electrodes, the lighting device comprising: a DC/DC converter that converts a direct voltage supplied from a DC power supply circuit to a direct current; a DC/AC inverter that controls the direct current supplied from the DC/DC converter so as to generate and supply an alternating voltage and alternating current at a predetermined frequency to a high-pressure discharge lamp; a high voltage generator that generates a high voltage for causing a start of the high-pressure discharge lamp; a lamp current detector that detects a lamp current; a lamp voltage detector that detects a lamp voltage; and a control circuit that controls the DC/DC converter and the DC/AC inverter based on output signals of the lamp current detector and the lamp voltage detector, wherein the lighting device controls so that constant current control is performed first after completion of a starting operation performed at a beginning of lighting and then the lighting is shifted to constant power lighting, the control circuit is configured so as to control an operation such that, except during a modulation forbidden period set as a certain period from the completion of the starting operation, a frequency of the alternating current is subjected to frequency modulation control for being changed alternately between at least a first frequency and a second frequency having higher audibility than the first frequency, in which the higher audibility is determined based on a relationship between loudness and frequency, and during the modulation forbidden period defined as a period (a) from the completion of the starting operation until a predetermined time before the lighting is shifted to the constant power lighting, (b) from the completion of the starting operation until the lighting is shifted to the constant power lighting, or (c) from the completion of the starting operation until a predetermined time after the lighting has been shifted to the constant power lighting, the frequency modulation control is not performed after an alternating current with a third frequency lower than the second frequency is supplied.