DISCHARGE LAMP LIGHTING DEVICE AND ILLUMINATION DEVICE

摘要

An illumination device which can dim or vanish a discharge lamp at the end of its service life without using any complex protective circuit even with a discharge lamp in the shape of a fine tube. A high frequency is supplied by an inverter circuit (4) to a load circuit (5) including a discharge lamp (FL), an inductance (L1) and a capacitance (C1), thus carrying out full lighting or dimming of the discharge lamp (FL). At the time of full lighting, load characteristics of relatively low open voltage and large short-circuit current are provided to the load circuit. At the time of dimming, load characteristics of relatively high open voltage and small short-circuit current are provided. When the service life of the discharge lamp (FL) comes to an end at the time of full lighting, the lamp voltage becomes higher than the open voltage of the load circuit (5) and the discharge lamp (FL) vanishes. When the service life comes to an end at the time of dimming, full lighting is started. When the service life then comes to an end, the discharge lamp (FL) vanishes. Since no abnormal temperature rise occurs near an electrode, a glass bulb, a base, and a socket are not melted.