| 摘要 |
PURPOSE:To obtain a bubble-free airtight sealed window using an external metal ring with the inner diameter exceeding 20mm. while having not step on the inner surface by setting the inner diameter of the external metal ring and the outer diameter of a transparent glass disc in a specified relationship. CONSTITUTION:When the inner diameter of an external metal ring is represented by (a) while the outer diameter of a transparent glass disc (b), a-b=0.01a (+0.1 or between +0.1 and -0) mm. is set when in the range of a=20-45mm. and a-b= 0.50-0.60mm. when (a)>45mm.. As (a) and (b) are set in this manner, tensile stress acting on the transparent glass melted can be controlled within a specified value to prevent the generation of bubbles even if the transparent glass happens to deposit gradually over the entire circumference from a part of the periphery of the external metal ring when the transparent glass disc is melted by heat and deposits on the inner surface thereof. In the assembly, the external metal ring 15 with the inner diameter (a) exceeding 20mm. while having no step on the inner surface thereof is placed on a sealing jig 7 made of graphite and the transparent glass disc 16a with the outer diameter (b) is arranged in the external metal ring 15. |
