Patent ID: 6911788

Claim:
An electronic ballast having a photocell circuit unit ( 100 ), a DC transformation unit ( 200 ) and a CF lamp driving circuit unit ( 400 ), being characterized in that the CF lamp driving circuit unit ( 400 ) comprises: a voltage divider ( 401 ) for dividing power supplied from the DC transformation unit ( 200 ) into a lamp power and a circuit driving power; field effect transistors Q 1 and Q 2 for controlling a voltage of the circuit driving power supplied from the voltage divider ( 401 ) to provide a voltage for high frequency oscillation; a resistor (R 12 ) and diodes (D 7 , D 8 , and D 9 ) provided at a front stage of the field effect transistors (Q 1 and Q 2 ) for preventing a voltage higher than a predetermined voltage from being applied to the field effect transistors (Q 1 and Q 2 ); a triac (TA 2 ) for preventing line surge from being applied to gates of the field effect transistors (Q 1 and Q 2 ); Zenor diodes (D 12 and D 13 ) for making the voltage through the field effect transistors (Q 1 and Q 2 ) a constant voltage; a plurality of oscillation coils (L 3 ˜L 5 ) that oscillate at high frequency according to the constant voltage produced by the Zener diodes (D 12 and D 13 ) to generate a high frequency; a lamp for receiving the high frequency generated by the oscillation coils (L 3 and L 4 ) through a choke coil (CT) to turn on the lamp; and diodes (D 14 and D 15 ) and condensers (C 10 and C 11 ) connected to one side of the lamp for supressing a surge voltage when the lamp is connected to a socket in order to protect the lamp and the socket.