| 摘要 |
PURPOSE:To prevent blackening of a filament by making a drive circuit into a full bridge circuit and using a drive pulse interval variable form. CONSTITUTION:Drive elements Q1 and Q2 are connected in series, an end of the drive element Q1 side is connected to a power source terminal 31, the other end of the drive element Q2 side is grounded. Drive elements Q3 and Q4 are connected in series, and an end of the drive element Q3 side is connected to the power source terminal 31 and the other end of the drive element Q4 side is grounded. A fluorescent lamp 11 is connected between a junction of the drive elements Q1 and Q2 and that of the drive elements Q3 and Q4. The drive elements Q1-Q4 are respectively controlled by control logics 32-35. The control logics 32-35 are controlled by a dimming signal of a terminal 36. The filament section is very long in life and hardly blackened so that it is possible for the dimmer circuit to provide dimming in a great degree. |
