Patent ID: 6563275
Filing Date: 2003-05-13
Classification: H05B,Y02B

Abstract:
A discharge lamp lighting circuit comprising:a DCâ€”DC converting circuit for converting a DC input voltage into a positive polarity output and a negative polarity output, the DCâ€”DC converting circuit including a transformer and a switching element and a current auxiliary circuit having a capacitor to aid light-up of the discharge lamp; a DC-AC converting circuit for converting an output voltage of the DCâ€”DC converting circuit into an AC voltage by an alternating operation of a plurality of switching elements and then supplying the AC voltage to the discharge lamp; and a control circuit for controlling a power to be applied to the discharge lamp upon receipt of a detection signal for a voltage applied to the discharge lamp or a current flowing to the discharge lamp and for controlling an output of the DCâ€”DC converting circuit, wherein when alternatively applying the output voltage of the DCâ€”DC converting circuit to the discharge lamp, an output voltage on a non-load side in the outputs having positive and negative polarities which is not applied to the discharge lamp during the light-up of the discharge lamp is restricted to be equal to an output voltage on a side which is applied to the discharge lamp.