HIGH PRESSURE DISCHARGE LAMP LIGHTING DEVICE

PROBLEM TO BE SOLVED: To reduce the cost in a high pressure discharge lamp lighting device to light a high pressure discharge lamp. SOLUTION: Voltage of an input coil W1 is inputted and cut off by a transistor Q5 , and voltage is generated in driving coils W3a , W3b , W3c and W3d , and bipolar transistors BT1 and BT3 or bipolar transistors BT2 , and BT4 are turned on by voltage of respective capacitors Co connected to them, and its ON operation is alternately repeated, and AC voltage having a rectangular wave is supplied to a high pressure discharge lamp LP, and it is lighted. An ON resistance of a transistor Q7 is controlled according to terminal voltage of the high pressure discharge lamp LP, and ON time of the transistor Q5 is controlled, and voltage of the capacitors Co is controlled, and a driving condition of the bipolar transistors BT1 , BT2 , BT3 and BT4 is made always proper.