| 摘要 |
<p>A security screen (5) comprises: a shutter frame (6) securable in a window opening (1) in a building, with a first side facing the window and a reverse side facing away from the window inwardly of the building; a plurality of parallel blades (7) extending across the shutter frame (6), each said blade having in cross-section a shape which includes a point at each opposed edge of the blade and having a reinforcing axial member (8) extending therethrough and engaged in respective opposing sides of the shutter frame, the blades being linked together and rotatable such that rotation of one blade induces the other blades to rotate simultaneously between a closed position, in which the blades lie substantially parallel to the frame so as to form a continuous shutter, and an open position substantially normal to the closed position; and a sheet of transparent plastic material (10) mounted on the frame and extending across the frame at a predetermined distance from the edges of the blades when in the open position thereof whereby, in the event of an explosion outside the window causing a pressure wave to blow the window inwardly of the building, the plastic material contacts at least a portion of a pointed edge of at least one of the blades when in the open position to rotate to the closed position, thereby preventing ingress of the pressure wave and glass from the window into the building.</p> |
