| 摘要 |
PURPOSE: To provide a sensitive safety device by surrounding at least part of the circumference of a cover formed as an exhaustible vacuum foil, providing a tensioned non-elastic band kept into contact with the circumference, and providing the band with a visible mark band part. CONSTITUTION: A casing 1 has an instrument packaged under vacuum in a cover 2, and this instrument is surrounded by a band 3 at least partially contacted with the circumference of the cover 2. When the vacuum is lost by the leakage or penetration of gas into the cover 2, the cover 2 is expanded, and the tension in the band 3 is increased past a predetermined value, that is, a value keeping a target breaking point 6, whereby a green band 7 is hidden in the back of a viewing window 9 by the breakage of the target breaking point 6, and a red surface of a band guide 8 appears. A sensitive safety device can thus be provided.
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