| 摘要 |
<p>The invention relates to a Venetian blind that is closed in either direction, i.e., by tilting the slats in either direction from their horizontal position, the slats being tilted by motion transmitted to them from a gear, the gear being rotated by a worm, and the worm being rotated by a manually rotated wand that is connected to the worm. The gear is a sector of less than 360.degree. and is on the verge of rotating out of mesh with the worm upon the blind reaching its closed position in either direction, the gear retrogresses a little upon rotating out of mesh with the worm. The point at which the gear rotates out of mesh with the worm is a little beyond the point at which the blind reaches its closed position and at least as far beyond such point as the retrogression of the gear upon rotating out of mesh with the worm, whereby the retrogression of the gear takes place entirely beyond the point at which the blind reaches its closed position and, thereby, the blind is protected against retrogressive opening movement. This arrangement is advantageous over the prior art in that it obviates the possibility of damage or adverse effect upon the blind due to continued turning by the operator, beyond the point where the blind is fully closed.</p> |
