| 摘要 |
PURPOSE:To permit a captioned lamp to stably discharge from the beginning of the lighting thereof by providing an electrode bar while allowing the tip thereof to project from an outer coil, specifying a ratio between a lamp current flowing at the lighting of the lamp and the length of the projecting electrode bar, and providing on the tip of said bar an electron emissive material in a range separated by 1.0mm. from the said tip. CONSTITUTION:Electrical conductors 6, 7 penetrate the center of end caps 2, 3 of a luminous lamp surrounding vessel 1. Electrodes 8, 9 are fixed on the tips of the conductors 6, 7, and sodium, buffer gas metal 10, and starting noble gas are encapsulated in the luminous lamp. An electrode bar 11 is provided on the electrode 8 or 9 so as to project from an outer coil 12, on whose bar 11 an electron emissive material 13 is deposited within a range of 1mm. from the tip thereof. An inner coil 14 on which an electron emissive material is deposited is provided inside the coil 12, and a shielding coil 15 on which an electron emissive material is not deposited is provided on the tip side of the coil 14. It is possible to obtain a high pressure discharge lamp stable in an electrode brightness from the beginning of the lighting of the discharge lamp by setting it so as to satisfy a relation given by a concerning formula assuming that the length of the electrode bar 11 projecting from the coil 12 is Lmm. and a lamp current at the lighting is 1A. |
