| 摘要 |
<p>The frame denies birds access to ledges on public buildings, comprising a rotatable cage mounted on an axle which is parallel to the protected ledge. The system may use rods (2,3) extending between two plates (1) to form an extended squirrel cage, the plates being mounted free to rotate on pivots fixed to the building. The rods may be substituted by cables maintained in a state of tension by a coil spring (4) incorporated in an axial shaft (2), or the form and constituent material of the plates may be used to promote cable tension. The cage may be rotated by a motor, and the openwork structure may be replaced by a tube of a round or polygonal section.</p> |
