| 摘要 |
PURPOSE:To simplify a circuit by composing a stabilizing circuit of a serial resonance circuit in such a structure that semiconductor switch control frequency numbers of the circuit are switched between two modes so as to perform preheating of a fluorescent lamp at the time of a high frequency number and lighting at the time of a low frequency number. CONSTITUTION:If a DC source voltage (a) and a control input signal (b) of 'H' are inputted to a DC source E and a control signal terminal 16 respectively, a semiconductor switch 24 becomes 'on' by the signal (b), and a timing resistance 23 gets o be in parallel with a timing resistance 22. A generation frequency F0 for control output is set based on a combined resistance value of these and a timing capacity 21. Next if the signal (b) becomes 'L', then the switch 24 becomes 'off', and a generation frequency number f1 for control output is set based on the resistance 22 and the timing capacity 21. For preheating, the semiconductor control switch is activated at the operating frequency number of f0, and preheating current goes through a current rectifier 13 and the filament of a fluorescent lamp 1 to a starting capacitor 14 to preheat the filament. If the operation frequency number is changed into F1, and if it gets close to a resonance frequency number, high voltages at both ends of the starting capacitor 14 gets a lamp 1 on. |
