Claims
- 1. An operating device for a Venetian blind which includes an elongated top housing, a horizontally disposed shaft journalled in the top housing, a plurality of horizontal slats suspended one above another from the top housing, each of the slats having two opposite longitudinal sides, a bottom rail disposed below the slats, a plurality of pull ropes, each of the pull ropes having a first end which passes through the housing and through the slats and which is mounted to the bottom rail, and a second end which extends out of the housing, a plurality of pairs of tilting cords disposed on the opposite longitudinal sides of the slats and having upper ends secured to the shaft and lower ends mounted on the bottom rail, and a plurality of suspending strings disposed below each of the slats and interconnecting the tilting cords, said operating device comprising:
- a hollow positioning tube adapted to be coupled to the shaft of the Venetian blind such that axial rotation of said positioning tube results in corresponding axial rotation of the shaft to tilt the slats, said positioning tube confining a receiving space that is adapted to permit extension of the second ends of the pull ropes thereinto;
- a stationary roller disposed in said receiving space and mounted rotatably to said positioning tube;
- a releasable clamping unit provided in said receiving space, said releasable clamping unit including a movable roller suspended in said receiving space at one side of said stationary roller such that said stationary roller and said movable roller are adapted to permit extension of the pull ropes therebetween, a biasing spring for biasing said movable roller toward said stationary roller that said movable roller cooperates with said stationary roller in order to be adapted to clamp the pull ropes therebetween, said biasing spring including a horizontal base portion and a pair of inclined biasing arms which extend upwardly from said base portion and which have upper ends that support rotatably said movable roller for suspending said movable roller in said receiving space of said positioning tube, said positioning tube being formed with retaining means for retaining said base portion of said biasing spring therein, said positioning tube having a peripheral wall with an axially extending first radial slot formed therethrough; and an elongated sleeve mounted coaxially on and slidable axially relative to said positioning tube, said elongated sleeve being associated operably with said releasable clamping unit so that said movable roller is moved away from said stationary roller for releasing the pull ropes when said elongated sleeve is moved downwardly relative to said positioning tube, said elongated sleeve being provided with a first insert pin which extends through said first radial slot and into said receiving space and which depresses at least one of said biasing arms of said biasing spring, said first insert pin compressing said biasing spring so as to move said movable roller away from said stationary roller for releasing the pull ropes when said elongated sleeve is moved downwardly relative to said positioning tube.
- 2. The operating device according to claim 1, wherein said positioning tube has a transverse base wall formed within said receiving space, said base wall having a peripheral portion and a central portion that is indented relative to said peripheral portion, said base wall further having an opposite pair of retaining plates that extend from said peripheral portion toward said central portion to define a retaining groove with said central portion and that serve as said retaining means for retaining said base portion of said biasing spring.
- 3. The operating device according to claim 1, wherein said positioning tube has an inner surface formed with a retaining protrusion which has a curved contact face, said biasing spring biasing said movable roller to move along said curved contact face such that said movable roller is retained fittingly and removably between said stationary roller and said curved contact face.
- 4. The operating device according to claim 3, wherein said movable roller is formed with axially extending teeth therearound, said curved contact face of said retaining protrusion being formed with teeth therealong for meshing with said teeth of said movable roller.
- 5. The operating device according to claim 1, further comprising a compression spring disposed in said positioning tube, said peripheral wall of said positioning tube further having an axially extending second radial slot formed therethrough, said elongated sleeve being provided with a second insert pin which extends through said second radial slot and into said receiving space and which depresses said compression spring, thereby permitting compression of said compression spring when said elongated sleeve is moved downwardly relative to said positioning tube to generate a restoring force for moving said elongated sleeve upwardly relative to said positioning tube when said elongated sleeve is released.
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part (CIP) of U.S. patent application Ser. No. 08/844,406, filed on Apr. 18, 1997, now U.S. Pat. No. 5,749,405.
US Referenced Citations (10)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
844406 |
Apr 1997 |
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