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US3980328A Doorbar system 失效
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Doorbar system
摘要:
Improvement in a doorbar device for barring the door of a doorway, the doorway having doorjambs and a door therefor, the door having a doorknob, the doorbar device comprising a doorknob constructed to be affixed to the doorjambs of the doorway to extend across and bar the door from being opened, the doorbar device also comprising a mechanism for applying a force upon the doorknob to prevent turning thereof.
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