1. Field of the Invention
This invention relates to a lockable cord pulling device, more particularly to a lockable cord pulling device adapted to be mounted on a header unit of a window covering for raising and lowering a lowermost slat relative to the header unit in an upright direction.
2. Description of the Related Art
Referring to
The object of the present invention is to provide a lockable cord pulling device, in which the angle of a pull cord relative to a vertical direction when the pull cord is operated to raise or lower slats of a window covering or to position the slats at a desired height is relatively small, thereby rendering operation of the pull cord convenient. Besides, operation of the pull cord will not be affected even if the window covering is in close proximity to a wall of a room.
According to this invention, the lockable cord pulling device includes a mounting member, a pulley roller, a pull cord, and a lock roller. The mounting member includes a mount wall which is adapted to be disposed in a header unit of a window covering, and which extends towards a right end of the header unit to terminate at a lateral edge, an abutment wall which is disposed proximate to the lateral edge, which extends in a transverse direction, and which includes upper and lower areas opposite to each other in a vertical direction, and an axle which extends from the mount wall along a rotating axis in the transverse direction, and which cooperates with the upper area to define a line of length that is radial to the rotating axis, and that is normal to the upper area. The pulley roller is rotatably mounted on the axle about the rotating axis, and has a pulley rim that intersects the line of length at a cord engaging point. The pull cord has an actuated end adapted to couple with a lowermost slat of the window covering, a pulled end opposite to the actuated end, and a guided segment which is interposed between the actuated end and the pulled end, and which is trained on the pulley rim so as to form an underlying region that is between the cord engaging point and the pulled end, and that cooperates with the abutment wall to define a moving route oriented in the vertical direction. The lock roller has a roller rim, and is disposed to be movable along the moving route between an unlocked position where the lock roller is rested closer to the lower area, and a locked position where the lock roller is suspended closer to the upper area. The lock roller is configured such that once the pulled end is pulled to bring the underlying region of the pull cord into frictional engagement with the roller rim, subsequent downward pulling of the pulled end along a path in the upright direction to tense the underlying region will force the lock roller to turn counterclockwise so as to roll across the lower area along the moving route to the locked position, where the lock roller is stuck between the pulley rim and the abutment wall by virtue of an increased dragging force of the underlying region which acts on the roller rim and which is generated as a result of said roller rim approaching the cord engaging point, and such that the lock roller is relieved from the increased dragging force and is allowed to fall into the unlocked position by virtue of gravity once the pulled end is pulled leftwards away from the path to tense the underlying region.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention, with reference to the accompanying drawings, in which:
Referring to
The mounting member 10 includes a pair of mount walls 12 which are adapted to be disposed in the header unit 100, which are spaced apart from each other in a transverse direction relative to both the upright and longitudinal directions, and each of which extends towards the right end to terminate at a lateral edge, an abutment wall 15 which is disposed proximate to the lateral edge, which extends in the transverse direction, and which has an abutment surface 151 that extends in a vertical direction and that includes upper and lower areas 153, 152 opposite to each other in the vertical direction, a right engaging wall 14 which resiliently extends from the lateral edges of the mount walls 12 in the transverse direction, and a left engaging wall 13 which is spaced apart from the abutment wall 15 and the right engaging wall 14 in the longitudinal direction. The right and left engaging walls 14, 13 extend downwardly to terminate at right and left bottom edges 141, 131, respectively, which define an access opening 19 therebetween. The left and right bottom edges 131, 141 respectively have left and right engaging holes 17, 18. An axle 16 extends from one of the mount walls 12 along a rotating axis (X) in the transverse direction, and cooperates with the upper area 153 to define a line of length (L) that is radial to the rotating axis (X), and that is normal to the upper area 153. When the mounting member 10 is mounted in the header unit 100, the left engaging wall 13 is first engaged with an inner edge of the header unit 100, and the right engaging wall 14 is then engaged with an opposite inner edge of the header unit 100 by virtue of its resilience.
The pulley roller 20 is rotatably mounted on the axle 16 about the rotating axis (X), and has a pulley rim 21 which intersects the line of length (L) at a cord engaging point (P). The pull cord 50 has an actuated end 51 adapted to couple with the lowermost slat, a pulled end 52 opposite to the actuated end 51, and a guided segment which is interposed between the actuated end 51 and the pulled end 52, and which is trained on the pulley rim 21 so as to form an underlying region 53 that is between the cord engaging point (P) and the pulled end 52, and that cooperates with the abutment wall 15 to define a moving route 11 oriented in the vertical direction and communicated with the access opening 19.
The lock roller 30 has a roller rim 31, is received in the moving route 11 from the access opening 19, and is movable along the moving route 11 between an unlocked position, as shown in
Therefore, when it is desired to move the lock roller 30 to the locked position, as shown in
Moreover, when it is desired to move the lock roller 30 to the unlocked position, as shown in
The leaf spring 40 has left and right spring ends 41, 42 which are respectively inserted into the left and right engaging holes 17, 18 such that the leaf spring 40 extends across the access opening 19 to prevent removal of the lock roller 30 from the access opening 19. Preferably, the right bottom edge 141 has a guiding surface 142 that is formed to be communicated with the right engaging hole 18 so as to facilitate insertion of the right spring end 42 of the leaf spring 40 into the right engaging hole 18.
As illustrated, since the abutment surface 151 extends in the vertical direction, the angle of the pulled end 52 relative to the vertical direction when the pulled end 52 is operated to raise or lower the lowermost slat (i.e. the lock roller 30 is moved in the unlocked position) or to position the lowermost slat at a desired height (i.e. the lock roller 30 is moved to the locked position) can be quite small. Thus, the operation of the pull cord 50 is convenient and will not be affected by the surrounding conditions, especially when the pull cord 50 is disposed in close proximity to a wall of the room. Moreover, during assembly, the left spring end 41 of the leaf spring 40 can be first inserted into the left engaging hole 17, and the right spring end 42 is then inserted into the right engaging hole 18 guided by the guiding surface 142. Thus, assembly of the leaf spring 40 can be easily conducted without the need to use any tools.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.