LIGHT REGULATED LIGHTING DEVICE

PROBLEM TO BE SOLVED: To eliminate the possibility of burnout of apparatus, eliminate temperature characteristic, and make input output characteristics sharp by using an operational amplifier capable of outputting an output voltage up to a power supply voltage as an amplifier at a final stage for delivering a modulated light signal to a lighting control part. SOLUTION: A lighting control part 5 for control of switching on and off of a switching element of an inverter circuit 3 turns on a switching element alternately, and a dc voltage from a rectified smoothing circuit 2 is inverted into a high-frequency voltage and the high-frequency voltage is supplied to a load 4. A rail-to-rail operational amplifier 7 is used as an amplifier at the final stage of a receiving part 6 for delivering a modulated light signal from the external to the lighting control part 5. This operational amplifier is capable of outputting a voltage up to a power source voltage. Thus, input and output characteristics are made sharp, errors in changing the temperature is reduced, and control of lighting modulated light is conducted with high accuracy. Also, the operational amplifier 7 becomes a safety side for decreasing the luminous intensity, even when an output is reduced because the amplifier 7 is out of order, and burning of a discharge lamp is prevented.