| 摘要 |
PURPOSE:In an alumina ceramic tube having the inner diameter longer than 15mm., to prevent the lateral crack and to produce the reliable lamp having long service life by regulating the thickness of the alumina ceramic tube, the thickness of the alumina ceramic encapsulator and the projected height of the electrode. CONSTITUTION:In a lamp the thickness of an alumina ceramic tube 1 is made to be t1 while the thickness of the alumina ceramic encapsulator 2 is made t2 and the height of the electrode is made to be (h). If the thickness of the tube wall of the alumina ceramic tube 1 is thick, it will cause the longitudinal crack due to the temperature difference between the inner and outer faces of the tube. Since the stress due to said temperature difference exceeds over the mechanical strength, it will cause the longitudinal crack. Consequently the thickness is limited below 2.5mm.. If the thickness t2 of the alumina ceramic encapsulator 2 is thick, the thermal capasity of the encapsulator 2 will also increase thereby it must capacity of the encapsulator 2 will also increase thereby it must satisfy the relation t1/t<=3. Since the radiation from the electrode will heat the tube end section, the height (h) of the electrode must satisfy the relation 40mm.> h>=18mm.. |
