| 摘要 |
PROBLEM TO BE SOLVED: To provide a 'soft' lighting system by providing a circuit system which contains a load circuit having a lamp and a driving circuit and operates in the vicinity of resonance by free oscillation. SOLUTION: Before ignition, the series-parallel constitution is mainly attenuated by only an iron core loss of a lamp coil L1, and therefore, a resonance circuit to which a load is slightly imparted, offers voltage in the visinity of high resonance increased for ignition. In that case, an iron core magnetic loss in the lamp coil L1 increase in about 2.5-th power of the voltage acts basically and restrictively. A frequency generator behaves as a controlled voltage source. When the voltage exceeds the ignition voltage of the lamp, the parallel part of a load circuit (having the L1) is given the effective resistance of plasma discharge converted by a winding of the lamp coil L1 as the load, and a lighting frequency is increased, and an inductance L2 acts as a current limited lamp choke coil. As a result, the frequency generator behaves again as a controlled current source. |
