| 摘要 |
The unit includes the plaque (10) in red translucent plastic which has a moulded trihedral reflecting surface (10a) to ensure complete reflection. The plaque (10) is sealed by a plastic casing (20) using soldered or glued joints (11,23) at the edges. The plastic casing (20) has an undulating zone (21a) on its wall remote from the reflecting plaque (10). The undulating zone (21a) has a thickness which is chosen such that any increase in enclosed air pressure following a temperature rise results in a compensating deformation limiting the pressure rise and protecting the reflecting plaque from distortion. ADVANTAGE - Reflecting plaque is sealed and protected from distortion following any temperature and enclosed air pressure rise.
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