| 摘要 |
PURPOSE:To protect a lighting circuit from any overcurrent due to overload appearing at the end of lamp life and also the short circuit of a lamp filament by providing the first and second windings of a detecting transformer having its first winding and its second winding, wherein their winding directions are turned respectively to negate their magnetic fields against each other, and also having its third winding respectively to their relevant preheating current conducting circuits on both sides of an electric discharge lamp, and then providing the third winding to a stopping circuit. CONSTITUTION:The first and second windings 12a, 12b of a detecting transformer 12 having its first winding 12a and its second winding 12b, wherein their winding directions are turned respectively to negate their magnetic fields against each other, and also having third winding 12c are provided respectively to their relevant preheating current conducting circuits on both sides of an electric discharge lamp 1, and the third winding 12c is then provided to a stopping circuit. Whereby the occurrence of an unbalanced preheating current causes the magnetic fields of the first and second windings 12a, 12b not to be negated against each other, and therefore the third winding 12c may induce a voltage exceeding its steady-state voltage for stopping operation of a lighting circuit to protect the lighting circuit from any overcurrent due to overload appearing at the end of lamp life and also the short circuit of a lamp filament by means of a single circuit. |
