Discharge-lamp lighting device

A discharge-lamp lighting device comprising:

• a direct-current power generation circuit that generates direct-current power from external power,
• a rectangular-wave generation circuit that converts the direct-current power to rectangular-wave alternating-current power,
• a pulse generating circuit that superposes high-voltage pulses on the rectangular-wave power output from the rectangular-wave generation circuit and starts a discharge lamp,
• lamp-voltage detection means for detecting, in digital form, a lamp voltage supplied to the discharge lamp, and
• pulse-generation command means for issuing a pulse generation command to the pulse generating circuit when the value detected by the lamp-voltage detection means reaches a predetermined no-load-voltage determination level,
• input-voltage detection means for detecting the input voltage of the direct-current power generation circuit in digital form, and
• input-voltage judging means for giving the detection signal of the input voltage to the pulse-generation command means according to the value detected by the input-voltage detection means, and
• wherein the pulse-generation command means issue the pulse generation command when the detected value of the lamp voltage reaches the no-load-voltage determination level and when the detection signal of the input voltage is received.