| 摘要 |
PROBLEM TO BE SOLVED: To surely carry out the resonance drive operation of a composite transformer by so constituting a power circuit as to inhibit the continuity of forward winding output until the output voltage before rectification of a flyback winding falls under the specified voltage. SOLUTION: The circuit is so constituted as to inhibit the electric continuity until the output of the 2VU winding being a forward winding 32 for low voltage may amount to a specified value, supplying the voltage controller of 24VU with the output of the 24VR winding being the flyback winding 31 for low voltage of a composite transformer 37. And, the light start signal of a fluorescent lamp 21 is inputted, and a switching element 26 for drive of a fluorescent lamp is turned off, and the voltage of the winding 23 for drive of the fluorescent lamp of the composite transformer 37 is applied to both ends of the fluorescent lamp 21. But, until the fluorescent lamp 21 shifts to light condition, the output of a comparator 105 is short-circuit compulsively by a zero cross timing detecting circuit 107 until the output of the winding of 24VR becomes zero volt. As a result, the resonance drive operation of the composite transformer can be carried out surely. |
