| 摘要 |
PURPOSE: To improve luminous efficiency, and/or reduce a lamp cost. CONSTITUTION: A reflecting layer 2, composed of magnesium oxide having a mean particle diameter of 0.5-5.0μm, is formed in the inner surface of a glass bulb 1. The adhering quantity of the layer 2 is set in a range of 0.1-3.2mg/cm<2> . A luminous layer 3 is overlappedly formed onto the layer 2. The layer 3 is constituted of, e.g. an active germanium fluoride acid magnesium phosphor with manganese.
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