| 摘要 |
PURPOSE:To prevent the defective lighting due to magnetic saturation by feeding currents to bypass routes of discharge elements from corresponding systems during the lights-out control period of DC-lighted discharge elements. CONSTITUTION:Lighting control signals are fed to terminals 78, 88 respectively. The lighting signals are made the L-level during the lighting period and the H-level during the lights-out period. The rectangular voltage is generated on the secondary side of a transistor 34. Both transistors(Tr) 77, 87 are set to off during the period A, and currents flow in DC-lighted discharge tubes 75, 85 in the cycle when lines 61, 62 are made positive respectively. The H-level is applied to the base of the Tr 87 during the period B, the Tr 87 is turned on, and a current flows in a bypass route. The control signal with the H-level is partially applied to the base of the Tr 77, a current flows in a bypass route during the period of the H-level, and a current flows in the discharge tube 75 during the period of the L-level. The biased magnetization of the transformer 34 can be prevented. |
