The invention relates to window coverings modification kit and is more specifically related to cordless blinds for covering window openings modification kit and, more particularly to cordless window coverings modification kit for tall windows.

A damping device of a window covering is provided, including a headrail, a covering material, and a driving device, wherein the driving device is located in the headrail to raise and extend the covering material. The damping device is provided in the headrail, and includes a metal member and a magnetic member, wherein at least a magnetic pole of the magnetic member faces the metal member. The metal member is located within a magnetic field of the magnetic member. Either one or both the metal member and the magnetic member is drivable by the driving device to make the metal member and the magnetic member move relative to each other. Whereby, the damping device is able to provide a desired damping effect at different temperature or after a long period use, such that the rotation of the metal member and the movement of the covering material are slowed down.

A damping device of a window covering is provided, including a headrail, a covering material, and a driving device, wherein the driving device is located in the headrail to raise and extend the covering material. The damping device is provided in the headrail, and includes a metal member and a magnetic member, wherein at least a magnetic pole of the magnetic member faces the metal member. The metal member is located within a magnetic field of the magnetic member. Either one or both the metal member and the magnetic member is drivable by the driving device to make the metal member and the magnetic member move relative to each other. Whereby, the damping device is able to provide a desired damping effect at different temperature or after a long period use, such that the rotation of the metal member and the movement of the covering material are slowed down.

A window blind includes a headrail, two lift cords, a blind body, a bottom rail and two cord winding devices. The two cord winding devices are respectively installed on the bottom of the bottom rail. Subject to the technical feature that the other ends of the two lift cords are respectively tied to the adjustment columns of the two cord winding devices, if the winding stroke is inconsistent and the blind body is folded unevenly or skewed when the window blind is folded or stretched, the adjustment column of one cord winding device can be fine-adjusted to let the respective lift cord be gradually wound and covered on the adjustment column, so that the bottom rail and the blind body can be gradually adjusted to be substantially parallel to the bottom of the headrail, thereby effectively achieving the effect of fine-tuning and correcting the blind body.

A window blind includes a headrail, two lift cords, a blind body, a bottom rail and two cord winding devices. The two cord winding devices are respectively installed on the bottom of the bottom rail. Subject to the technical feature that the other ends of the two lift cords are respectively tied to the adjustment columns of the two cord winding devices, if the winding stroke is inconsistent and the blind body is folded unevenly or skewed when the window blind is folded or stretched, the adjustment column of one cord winding device can be fine-adjusted to let the respective lift cord be gradually wound and covered on the adjustment column, so that the bottom rail and the blind body can be gradually adjusted to be substantially parallel to the bottom of the headrail, thereby effectively achieving the effect of fine-tuning and correcting the blind body.

A window covering includes a positional adjustment mechanism connected to a first rail that includes a spring motor unit, a first lift cord pulley connected to the spring motor unit, a first lift cord collection mechanism having a first roller positioned in the first rail, and a first lift cord that extends from the first lift cord pulley through window covering material such that a portion of the first lift cord passes along the first roller. The first roller is configured so that it only rotates a pre-selected number of revolutions when the window covering material is moved from the extended position to the retracted such that the first roller no longer rotates in the second rotational direction as the window covering material is moved from an extended position to a retracted position after having rotated the pre-selected number of revolutions in the second rotational direction.

A window covering includes a positional adjustment mechanism connected to a first rail that includes a spring motor unit, a first lift cord pulley connected to the spring motor unit, a first lift cord collection mechanism having a first roller positioned in the first rail, and a first lift cord that extends from the first lift cord pulley through window covering material such that a portion of the first lift cord passes along the first roller. The first roller is configured so that it only rotates a pre-selected number of revolutions when the window covering material is moved from the extended position to the retracted such that the first roller no longer rotates in the second rotational direction as the window covering material is moved from an extended position to a retracted position after having rotated the pre-selected number of revolutions in the second rotational direction.

A locking mechanism is disclosed, which is installed in a movable rail of a window covering, and is passed through by a cord. The locking mechanism includes a locking unit and a pressing member, wherein the locking unit includes a stopping member which is movable between a first position and a second position. The stopping member is normally located at the first position to abut against the cord, which prevents the cord from moving relative to the locking mechanism, whereby to maintain the position of the movable rail. By pressing the pressing member, the stopping member is moved to the second position, where the stopping member no longer abuts against the cord. Therefore, when the movable rail is moved in a direction away from a fixed rail of the window covering, the cord can move relative to the locking mechanism. Whereby, the movable rail can be smoothly moved downward.

A locking mechanism is disclosed, which is installed in a movable rail of a window covering, and is passed through by a cord. The locking mechanism includes a locking unit and a pressing member, wherein the locking unit includes a stopping member which is movable between a first position and a second position. The stopping member is normally located at the first position to abut against the cord, which prevents the cord from moving relative to the locking mechanism, whereby to maintain the position of the movable rail. By pressing the pressing member, the stopping member is moved to the second position, where the stopping member no longer abuts against the cord. Therefore, when the movable rail is moved in a direction away from a fixed rail of the window covering, the cord can move relative to the locking mechanism. Whereby, the movable rail can be smoothly moved downward.

A spring drive system for a window shade includes a housing, a first and a second gear engaged with each other and respectively assembled about a first and a second pivot axis, two springs respectively assembled at two opposite sides of the second gear and respectively connected with two take-up reels provided on the first gear, a first cord drum and a third gear fixedly connected with each other and assembled about a third pivot axis, the first and third gears being respectively located at different levels along the first and third pivot axes and respectively engaged with a first gear train, a second cord drum and a fourth gear fixedly connected with each other and assembled about a fourth pivot axis, the second and fourth gears being respectively located at different levels along the second and fourth pivot axes and respectively engaged with a second gear train.