The invention relates to a tensioning device for tensioning an endless loop control element in a window blind and particularly relates to a blind operating mechanism and an endless loop blind control element for operating the blind mechanism and having: a channel extending from an upper end to a lower end, with the endless loop blind control element enclosed within the channel; a connector supporting the upper end of the channel adjacent to the blind operating mechanism; and, the tensioning device on the lower end of the channel. The invention also discloses a narrow profile control element having a sprocket wheel with the channel, connector and tensioning device.

A window blind position damping device is applied to a window blind with slat being expanded horizontally, forming a damping to a pull cord effectively when the slat is pulled down at any height, so as to define the height. The window blind position damping device includes a machine part, and an interior of the machine part has a spring scroll wheel and a position damping device which links a pull cord through a provided release idler. A damping shear pillar is vertically disposed on a base plate of the provided machine part, between an outlet of the release idler and an opening. By a provided shear ridge, the damping shear pillar shears an overrun section of the pull cord that passes through, forming the damping and thereby defining and fixing the slat at any height when being expanded.

A window blind position damping device is applied to a window blind with slat being expanded horizontally, forming a damping to a pull cord effectively when the slat is pulled down at any height, so as to define the height. The window blind position damping device includes a machine part, and an interior of the machine part has a spring scroll wheel and a position damping device which links a pull cord through a provided release idler. A damping shear pillar is vertically disposed on a base plate of the provided machine part, between an outlet of the release idler and an opening. By a provided shear ridge, the damping shear pillar shears an overrun section of the pull cord that passes through, forming the damping and thereby defining and fixing the slat at any height when being expanded.

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 window covering control assembly is used in a window covering system. The window covering control assembly comprises a driving module and a speed control module, and is provided in the shell, engaged to the weight element for simultaneous operation therewith. The driving module comprises a cord collecting assembly mounted in the shell. The cord collecting assembly is configured to operate in a first direction while a first driving force acting upon the cord collecting assembly such that the weight element descends away from the shell. The first driving force comprises at least a weight of the weight element. The speed control module is positioned corresponding to the driving module. A resistance force is selectively generated between the speed control module and the driving module, and this force reduces an operation speed of the cord collecting assembly in the first direction.

A window covering control assembly is used in a window covering system. The window covering control assembly comprises a driving module and a speed control module, and is provided in the shell, engaged to the weight element for simultaneous operation therewith. The driving module comprises a cord collecting assembly mounted in the shell. The cord collecting assembly is configured to operate in a first direction while a first driving force acting upon the cord collecting assembly such that the weight element descends away from the shell. The first driving force comprises at least a weight of the weight element. The speed control module is positioned corresponding to the driving module. A resistance force is selectively generated between the speed control module and the driving module, and this force reduces an operation speed of the cord collecting assembly in the first direction.

A blind without pull cord and a raising device. The blind includes a blind structure and at least one raising device. The blind structure has a fixed side and a movable side opposite to each other. The raising device includes a housing, a retracting component and a raising cord. The housing is connected to the movable side. The retracting component is rotatably disposed on the housing. Two opposite ends of the raising cord are connected to the blind structure and the retracting component, respectively. The retracting component is configured to raise the movable side relative to the fixed side via the raising cord.

A blind without pull cord and a raising device. The blind includes a blind structure and at least one raising device. The blind structure has a fixed side and a movable side opposite to each other. The raising device includes a housing, a retracting component and a raising cord. The housing is connected to the movable side. The retracting component is rotatably disposed on the housing. Two opposite ends of the raising cord are connected to the blind structure and the retracting component, respectively. The retracting component is configured to raise the movable side relative to the fixed side via the raising cord.

A retaining device for an operating member of a window shade includes a casing having an opening, a sliding part having a first and a second inner cavity, and a spring respectively connected with the sliding part and the casing. The sliding part is assembled with the casing, and is movable between a first and a second position, wherein the sliding part in the first position occludes the opening and has the first inner cavity exposed for insertion of an operating member of a window shade, and the sliding part in the second position has the first inner cavity retracted toward an interior of the casing while the second inner cavity overlaps with the opening for facilitating travel of an operating member of a window shade through the opening and the second inner cavity. The spring is operable to urge the sliding part to move toward the first position.