| 摘要 |
Abstract A roll blind includes: a safety cord connected to and wound around a chain pulley adapted to rotate the winding rod, 5 the safety cord having a separated lower end so that one side defines a lowering cord for pulling down the blind material and the other side defines a raising cord for rolling up the blind material; a bidirectional clutch unit adapted to raise/lower the blind material, the bidirectional clutch unit 10 being positioned between the chain pulley and a driving shaft of the winding rod, the bidirectional clutch unit having bidirectional protrusions formed on an inner peripheral surface of the chain pulley at an identical interval in a circumferential direction so that, when the lowering or 15 raising cord is pulled, the winding rod rotates together with the chain pulley, the bidirectional clutch unit having a number of rollers positioned between respective bidirectional protrusions on an outer peripheral surface of the driving shaft of the winding rod at an identical interval in the 20 circumferential direction; and a return operation unit having an elastic restoration member adapted to accumulate elastic restoration force, when pulling of the lowering or raising cord rotates the chain pulley, through a return pulley rotating together with the chain pulley, the return pulley 25 rotating the chain pulley backwards around the driving shaft of the winding rod, when the lowering or raising cord is released from the pulled condition, using the elastic restoration force accumulated in the elastic restoration member so that, without displacement of the blind material, 30 the safety cord returns to the original position. |
