| 摘要 |
<p>The mask which may be put on permanently, for example by connecting it to a helmet or support, without hindering the normal visibility, and which obscures automatically the visual field in those periods of time only, in which the electric arc is lighted. In this way, the free visibility is maintained up to the moment in which the arc is lighted, whereupon the visibility remains ensured even through the obscured glass, and the normal visibility is restored as soon as the arc is extinguished. The opaque mask has means for supporting it permanently before the operator's face and with normally clear window whose field can be obscured by an absorption means controlled, directly or indirectly, by the welding current.</p> |
