Patent ID: 7439680

Claim:
A lamp circuit apparatus for safely connecting the lamp to the equipment voltage ground (EVG), comprising a rectification circuit (D 1 -D 4 ) for rectifying a supplied power supply alternating voltage into a direct voltage, and an oscillating circuit (C 3 , L 1 , C 4 ) for converting said direct voltage into alternating voltage for driving the lamp to work, wherein said oscillating circuit comprises the DC-blocking capacitor (C 3 ), the oscillating inductor (L 1 ) and the oscillating capacitor (C 4 ) orderly connected in series, one end of said DC-blocking capacitor (C 3 ) is connected to the output rectification voltage of said rectification circuit, and another end thereof is connected to said oscillating inductor (L 1 ), while one end of said oscillating capacitor (C 4 ) is connected to the equipment voltage ground (EVG), and another end thereof is connected to the working voltage terminal of the lamp, characterized in that the ground terminal of the lamp is electrically connected to the equipment voltage ground (EVG) through a parallel circuit formed of a switch (S 1 ) and a high impedance capacitor (C 5 ), wherein said switch (S 1 ) is controlled by a control circuit provided within said apparatus to be closed only after the lamp is normally ignited, and to keep open under other states.