| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp for a vehicle which improves durability by preventing occurrence of a crack of a ceramic light emitting tube. SOLUTION: The discharge lamp for the vehicle includes a ceramic light emitting tube 5 in the inner portion of which a specific gas is enclosed, a pair of electrodes 9, 10 held in the ceramic light emitting tube, and an outer tube 6 which is made of glass and in the inner space of which the ceramic light emitting tube and the pair of the electrodes are accommodated. The ceramic light emitting tube is composed of a light emitting portion 7 in the inside of which an electric discharge is conducted by the pair of the electrodes to make a light emission and a pair of fine tubes 8, 8 which are connected with both of front and rear end portions of the light emitting portion and have smaller outer diameters than that of the light emitting portion. When H(mm) is a distance between an upper surface in the light emitting portion of the ceramic light emitting tube and an inner surface of the outer tube positioned to face the above upper surface and t(mm) is a thickness of the outer tube, the distance H shall be 0.3 or more and 3.0 or less, and the thickness shall be 0.5 or more and 2.5 or less, and a product H×t of the distance H by the thickness t shall be 0.3 or more and 3.0 or less. COPYRIGHT: (C)2009,JPO&INPIT
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