| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for preventing rapid unusual descent of a shutter curtain of a shutter device capable of preventing rapid unusual descent of the shutter curtain uncontrollably due to free rotation of a winding shaft of a chain when a chain is cut off while simplifying a structure of the shutter device. SOLUTION: A first sprocket wheel 11 is attached to the winding shaft for winding and unwinding the shutter curtain, a second sprocket wheel 12 is attached to a driving device for rotating the winding shaft, and the chain 13 is stretched around these sprocket wheels. A contact member 78 coming into contact with the chain 13 is attached to a turning member 75 of a rotation stop means 70, and the rotation stop means 70 is provided with a spring for turning and biasing the turning member 75 onto a side for engaging a protrusion 75B of the turning member 75 with teeth 11A of the sprocket wheel 11 centered on a central shaft 74. The protrusion 75B being an engaging part is engaged with the teeth 11A by cutting-off of the chain 13. COPYRIGHT: (C)2010,JPO&INPIT
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