| 摘要 |
PURPOSE:To improve life characteristics of a low pressure mercury vapor discharge lamp by measuring the specific surface area of the grains of electron emitting material BaO, SrO and CaO to be applied on the double coil filament of the said lamp to regulate the grain diameter within specified value. CONSTITUTION:The low pressure mercury vapor discharge lamp is constructed by applying electron emitting material on the double coil filament and enclosing inner gas and mercury in the tube. At this time, the electron emitting material is prepared by adding ZrO2 to the mixture of BaO, SrO and CaO, and at the same time, the specific surface area of the grains of BaO, SrO and CaO is measured to regulate the grain diameter so as the specific surface area of the grains to be kept in the range of 5X10<3>-10X10<3>cm<2>/g. Thus, by making the grain size very fine like this, higher adhesiveness and better heat efficiency can be obtained to improve emission characteristics of electrons, and even when the lamp is lighted under low current conditions such as in inverter circuit and so on sufficient life characteristics can be obtained.
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