| 摘要 |
PURPOSE:To enlarge light adjustment range and miniaturize and lighten the device stated in the title by connecting a phase control circuit in parallel to a condensor, and making the firing angle of the phase control circuit variable. CONSTITUTION:An advanced phase condensor 14 and a phase control circuit 18 are provided. The phase control circuit 18 comprises a chalk coil 20 for controlled current and a bidirectional thylister 22 both connected in parallel to an advanced phase condensor 14, and a resistance 24 and the series circuit of a condensor 26 both connected in parallel to the thylister 22 from the connecting point of the chalk coil 20 with the thylister 22. A composite current of an advanced phase condensor current with the control current of the phase control circuit 18 is supplied to a discharge lamp 1b by adjustment of the firing angle of the phase control circuit 18. Thus the secondary current supplied to the discharge lamp 16 is itself varied so that light adjustment is enabled over a wide range and also that the lighting device is miniaturized and lightened. |
