| 摘要 |
PURPOSE:To aim at improvement in the luminous efficiency of a lamp, by providing transparent and electrically conductive film over the inner face of a glass tube and connecting said film to each of both electrodes through diodes and resistances. CONSTITUTION:A lamp is lit by AC current, but when electrodes 15, and 16 act as a cathode and an anode respectively, a state of shortcircuit appears due to a forward voltage applied to a diode 3 while an open state of a diode 4 appears due to a reverse voltage applied to the diode 4. On the contrary, when electrode 15 and 16 act as an anode and a cathode, the diode 4 is shortcircuited to set a NESA film 2 always equipotential to the cathode. Accordingly, the potential of NESA-film 2 on a tube wall is kept lower than that of a positive column so that the electrons included in the positive column plasma may be subjected to the force acting toward the tube center caused by an electric field directed from the tube center toward the tube wall. Consequently, the amount of electrons scattering toward the tube wall is reduced and the efficiency of the lamp can be improved to that extent.
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