| 摘要 |
PROBLEM TO BE SOLVED: To eliminate danger of break by the rise of the internal pressure of a bulb by forming, on the outer surface of a ceramic bulb, a thin film having an expansion coefficient smaller than the ceramic. SOLUTION: A lamp 1 is formed of an outer tube 2 and a ceramic bulb 3 sealed therein, and a silica thin film 6 having an expansion coefficient smaller than the ceramic is formed on the outer surface of the bulb 3 in a thickness of about 500-1000Å. The thin film 6 is formed by applying a silica organic metal solvent to the outer surface of the bulb 3. Since the thin film 6 has an expansion coefficient smaller than the bulb 3 of the lamp 1, a compression stress is generated in the bulb 3, so that the break of the bulb 3 can be prevented to the tensile stress by the rise of internal pressure of the bulb 3 when lighting the lamp 1. Since the thin film 6 is formed by applying the silica organic metal solvent to the outer surface of the bulb 3, the formation of the thin film 6 can be performed at a relatively low temperature to facilitate manufacturing of the lamp 1.
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