BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a window blind, and more particularly to a window blind that can provide an excellent light-blocking effect when completely closed.

2. Description of the Prior Art

A conventional window blind usually includes a headrail, a bottom rail, and a plurality of slats between the headrail and the bottom rail, wherein the slats are horizontally suspended by ladder tapes. It is common for a window blind to have a lift cord assembly, which is connected to a lifting mechanism in the headrail with an end thereof, and is connected to the bottom rail with another end. By the driving of the lifting mechanism, the lift cord assembly could move the bottom rail toward or away from the headrail. In this way, the slats provided between the headrail and the bottom rail can be expanded or folded. The design of the lift cord assembly in a general window blind may include several corresponding pairs of lift cords, which respectively pass by the front and rear sides of the slats, or may include several lift cords respectively passing through center perforations of the slats. In most cases, there are usually two or more pairs of lift cords/two or more lift cords spaced out in a longitudinal direction of the slats. A ladder tape is composed of two warps and multiple wefts connected between the two warps; each of the slats is respectively placed on a corresponding weft and between the two warps. Each of said warps has an end connected to a rotatable modulation mechanism which is located in the headrail, and another end connected to the bottom rail. Rotating the modulation mechanism makes two warps create a relative vertical movement and approach each other, by which the slats that are originally placed on the wefts in a horizontal position can be correspondingly rotated, and so can the bottom rail. Rotations of different angles could provide different light-blocking effects, and therefore the amount of light allowed to pass through can be adjusted by such means.

However, when the slat assembly of a window blind is fully expanded, the position of the bottom rail is determined, and therefore the length of the lift cord assembly would be not changeable anymore despite the weight of the bottom rail being supported by the lift cord assembly and by the ladder tapes at the same time. In such circumstances, if one keeps maneuvering the modulation mechanism with the intention of rotating the slats to a fully closed position, the fixed length of the lift cord assembly would only allow the bottom rail to rotate to a limited extent. Take a window blind which has its lift cord assembly provided on the front and rear sides of the slats as an instance, the lengths of the lift cords on both sides are fixed once the slat assembly is fully expanded. In this situation, the length of the lift cord assembly cannot be changed even if the modulation mechanism is further maneuvered to create a relative vertical movement between the two warps of each ladder tape to turn the slats into a fully closed position, and therefore the rotation of the bottom rail is restricted by the fixed length of the lift cords, causing the bottom rail unable to reach a fully closed position. Consequently, the slats near the bottom rail cannot be rotated to the fully closed position, either. Therefore, the closure effect provided by the slats is not as good as expected.

To improve the above problem, some patents or patent applications, such as Chinese patent application No. 201710790554.X (i.e., U.S. patent application Ser. No. 16/105,976), have disclosed techniques that could further pull up the lift cords by interference while maneuvering a modulation mechanism, whereby the bottom rail could fully respond to the relative movement between two warps of a ladder tape and therefore be rotated as intended. However, such technique has a drawback: the force balanced between the bottom rail and the lifting mechanism would be disrupted while the lift cords are being pulled up, which causes the position of the bottom rail to raise slightly. After maneuvering the modulation mechanism several times, it could be easily noticed that the bottom rail is obviously raised to a higher position, especially when the slat assembly is in a fully expanded state. A window blind having an unintendedly raised bottom rail would have light leakage below the bottom rail. In other words, the area of a window which is actually covered by a fully expanded window blind may not be in line with the expectation of the user.

Similar defects can also be found in window blinds having lift cords on left and right sides that run through center bores of slats. Once the slat assembly is fully expanded, the lengths of lift cords are then fixed, and would not change along with the rotation of the modulation mechanism. Furthermore, since the lift cords are connected to the bottom rail at places that are not the rotation center of the bottom rail, the lift cords with fixed lengths would hinder the rotation of the parts near the connecting portions. As a result, the bottom rail is restricted by the support of the lift cords from being rotated to a fully closed position along with the ladder tapes. The slats near the bottom rail would also be affected and, therefore, not able to be turned to a fully closed position. The situations mentioned above all lead to the problem of light leakage, for the slats of a slat assembly near the bottom rail cannot be completely closed and, therefore, cannot block all the light.

Therefore, how to provide an excellent shading effect for an expected area when complete closure is required is still a problem to be solved in the industry of window blinds.

SUMMARY OF THE INVENTION

In view of the above, the objective of the present invention is to provide a window blind that has an excellent light-blocking effect for a blocked area of the window, and the blocked area could be maintained as expected. Therefore, the window covering provided in the present invention could solve an existing problem that light may still leak through the portion near the bottom rail even when a window blind is in the closed position.

The present invention provides a window blind, which includes a headrail, a covering assembly provided below the headrail, a lifting mechanism, a tilt mechanism, and an auxiliary unit provided between the lifting mechanism and the tilt mechanism. The covering assembly sequentially includes a plurality of slats and a bottom rail in a direction away from the headrail. The lifting mechanism includes a driving module and a lift cord assembly, wherein the driving module is provided in the headrail. The lift cord assembly includes a first cord and a second cord. An end of the lift cord assembly is operably connected to the driving module, while another end thereof is connected to the bottom rail. The lift cord assembly is adapted to be driven by the driving module to be released or retracted, whereby to expand or fold the covering assembly. The tilt mechanism includes a modulation module and a ladder tape, wherein the modulation module is provided in the headrail. The ladder tape includes two warps, and the slats are positioned between the warps. The modulation module is adapted to drive the warps of the ladder tape to create a relative vertical movement below the headrail, whereby to drive the slats of the covering assembly to rotate so as to block light or to allow light to pass therethrough. The covering assembly is defined to be in a first state when the slats and the bottom rail are substantially parallel to each other, and can be correspondingly rotated along with the relative vertical movement of the warps. On the other hand, the covering assembly is defined to be in a second state when at least one of the slats or the bottom rail is not correspondingly rotatable along with the relative vertical movement of the warps. When the covering assembly is in the second state, the auxiliary unit is adapted to be driven by the tilt mechanism, and the lifting mechanism is concurrently motivated by the auxiliary unit which is being driven, whereby to further release the lift cord assembly and therefore to change the covering assembly into the first state that the slats and the bottom rail are substantially parallel to each other again.

In an embodiment, when the lifting mechanism is concurrently motivated by the auxiliary unit to further release the lift cord assembly, the first cord and the second cord are synchronously released by a same length.

In an embodiment, the slats are positioned between the first cord and the second cord, and the first cord has a tension different from that of the second cord.

In an embodiment, the auxiliary unit includes a timing transmission mechanism and a driven member; the timing transmission mechanism is connected to the modulation module to be driven by the modulation module; the driven member connects the driving module and the timing transmission mechanism, and the timing transmission mechanism operably drives the driven member.

In an embodiment, the modulation module includes a modulation shaft, around which the timing transmission mechanism is provided, and the timing transmission mechanism is rotatable along with the modulation shaft. When the covering assembly is in the second state, the driven member is adapted to be driven by the timing transmission mechanism, and the driving module is concurrently motivated by the driven member which is being driven, whereby to release the lift cord assembly.

In an embodiment, the driving module includes a cord reel and an actuating device which is concurrently motivated when the cord reel is driven. The lift cord assembly is adapted to be concurrently motivated by the cord reel. The actuating device is adapted to provide a motivating force to the lift cord assembly, wherein the motivating force is for retracting the lift cord assembly back into the headrail.

In an embodiment, the actuating device includes a driving drum, a spring-receiving drum, and a torsion spring. The torsion spring connects the driving drum and the spring-receiving drum. The driving drum and the cord reel are connected in a manner that they are adapted to be concurrently motivated by each other, whereby to provide the motivating force to the cord reel.

In an embodiment, the driven member includes a toothed structure provided on the driving module, and the toothed structure concurrently moves with the cord reel. While the toothed structure is being driven by the timing transmission mechanism to concurrently motivate the cord reel to release the lift cord assembly, the motivating force has to be overcome.

In an embodiment, the timing transmission mechanism includes an incomplete gear, which is provided corresponding to the toothed structure. The incomplete gear concurrently rotates with the modulation shaft. When the covering assembly is in the first state, a toothed segment of the incomplete gear does not mesh with the toothed structure, so that the incomplete gear is adapted to independently rotate along with the modulation shaft relative to the toothed structure; when the covering assembly is in the second state, the toothed segment of the incomplete gear meshes with the toothed structure, so that the incomplete gear is adapted to be rotated along with a rotation of the modulation shaft, whereby to drive the toothed structure, which makes the cord reel rotate to further release the lift cord assembly.

In an embodiment, the timing transmission mechanism further includes an auxiliary gear, which is freely rotatable relative to the modulation shaft, and always meshes with the toothed structure.

In an embodiment, the timing transmission mechanism includes a first sleeve, a second sleeve, and a housing. The first sleeve and the second sleeve are provided on the modulation shaft and in the housing at intervals, wherein the first sleeve rotates synchronously with the modulation shaft, and is slidable relative to the modulation shaft. The second sleeve is freely rotatable relative to the modulation shaft, and always meshes with the toothed structure. When the covering assembly is in the first state, the first sleeve is driven by the modulation shaft to rotate, and is spaced out from the second sleeve; when the covering assembly is in the second state, the first sleeve is driven by the modulation shaft to rotate, and slides toward the second sleeve to become engaged with the second sleeve.

In an embodiment, the first sleeve has a first engaging portion, a first sleeve body, and a limiting portion. The first engaging portion is located at an end of the first sleeve body, and faces the second sleeve. The limiting portion is located at another end of the first sleeve body. The second sleeve has a second engaging portion, a second sleeve body, and a toothed ring. The second engaging portion is located at an end of the second sleeve body, and corresponds to the first engaging portion. The toothed ring fits around the second sleeve body and meshes with the toothed structure. When the covering assembly is in the second state, the first engaging portion engages with the second engaging portion, so that the second sleeve is adapted to rotate synchronously along with the first sleeve and the modulation shaft.

In an embodiment, the timing transmission mechanism further includes a restoring member. The housing covers the first engaging portion of the first sleeve and the second engaging portion of the second sleeve, and also covers at least a part of the first sleeve body and at least a part of the second sleeve body. The restoring member is provided near a side of the housing that corresponds to the limiting portion. The limiting portion is located between an abutting portion of the housing and the restoring member, and the restoring member provides the first sleeve a pushing force toward the second sleeve.

In an embodiment, the limiting portion of the first sleeve has a protrusion protruding toward the abutting portion of the housing, and an outline of the abutting portion has a notch formed in an axial direction of the housing. When the covering assembly is in the first state, the first sleeve is adapted to rotate along with a rotation of the modulation shaft, and is, due to the pushing force, adapted to make the protrusion abut against the abutting portion and move along the outline of the abutting portion; when the covering assembly is in the second state, the protrusion completely passes by the abutting portion and no longer contacts the abutting portion as the protrusion reaches where the notch is, and the first sleeve is moved by the pushing force in an axial direction of the modulation shaft, whereby the first engaging portion engages with the second engaging portion.

In an embodiment, the restoring member includes a blocker, which pushes against the limiting portion of the first sleeve to generate the pushing force. The limiting portion has another protrusion protruding in a direction opposite to the protrusion. When the covering assembly is in the second state, the first sleeve is adapted to rotate along with the rotation of the modulation shaft to make the another protrusion face the blocker, and the protrusion no longer contacts the abutting portion as the protrusion reaches where the notch is, whereby the first sleeve is moved toward the second sleeve by the pushing force.

In an embodiment, the restoring member includes an elastic member, which pushes against the first sleeve to generate the pushing force. When the covering assembly is in the second state, the first sleeve is adapted to rotate along with the modulation shaft, so that the protrusion no longer contacts the abutting portion as the protrusion reaches where the notch is, whereby the first sleeve is moved toward the second sleeve by the pushing force.

In an embodiment, the protrusion is helical, and includes a starting point and an ending point. When the covering assembly is in the second state, the ending point of the protrusion no longer contacts the abutting portion as the ending point reaches where the notch is, so that the first sleeve is moved toward the second sleeve by the pushing force, whereby the first engaging portion engages with the second engaging portion.

In an embodiment, the first sleeve further includes a delay member, which fits around the modulation shaft, and respectively corresponds to the first sleeve body and the restoring member. The restoring member exerts the pushing force on the delay member, and the delay member has a protruding part on a side thereof facing the first sleeve body. The first sleeve body has a path on a side thereof facing the delay member, and the protruding part is adapted to be driven by the modulation shaft to reciprocate along the path. Once the protruding part contacts an end of the path, the protruding part is able to drive the first sleeve body to rotate synchronously.

In an embodiment, the driving module further includes a transmission cord, which connects the cord reel and the lift cord assembly. The cord reel is adapted to be concurrently motivated by the actuating device to wind up or release the transmission cord, whereby to retract or release the lift cord assembly.

In an embodiment, the lifting mechanism further includes a movable seat assembly, which includes a movable seat and a positioning pin. The movable seat is movable in a longitudinal direction of the headrail, and the positioning pin is fixedly provided in the headrail. A segment of the lift cord assembly located in the headrail is arranged in a manner that runs back and forth between the movable seat and the positioning pin. An end of the transmission cord is connected to the movable seat, and another end thereof is connected to the cord reel. The cord reel is adapted to be concurrently motivated by the actuating device to retract or release the transmission cord, so that the lift cord assembly is, through the movable seat, concurrently motivated when the transmission cord is driven. When the driven member is driven by the timing transmission mechanism to concurrently motivate the cord reel to release the lift cord assembly, the motivating force provided by the actuating device has to be overcome.

In an embodiment, the driven member includes an interference device located between the cord reel and the lift cord assembly. The lifting mechanism further includes a movable seat assembly, which includes a movable seat and a positioning pin, wherein the movable seat is movable in a longitudinal direction of the headrail, and the positioning pin is fixedly provided in the headrail. A segment of the lift cord assembly located in the headrail is arranged in a manner that runs back and forth between the movable seat and the positioning pin. The transmission cord passes through the interference device, and has an end connected to the cord reel and another end connected to the movable seat. The cord reel is adapted to be concurrently motivated by the actuating device to retract or release the transmission cord, so that the lift cord assembly is, through the movable seat, concurrently motivated when the transmission cord is driven.

In an embodiment, the interference device includes a base, an interference member, and an elastic member. The interference member is movable relative to the base. Two end portions of the elastic member respectively abut against the interference member and the base. When the covering assembly is in the first state, the interference member twists the transmission cord, so that an actual cord length of the transmission cord from the cord reel to the movable seat is longer than a direct length from the cord reel to the movable seat. When the covering assembly is in the second state, the timing transmission mechanism is adapted to drive the interference member to move relative to the base, whereby to release the transmission cord twisted by the interference member, so that the movable seat is further moved in a direction away from the cord reel.

In an embodiment, the timing transmission mechanism includes an incomplete gear, and the interference member has a toothed structure provided corresponding to the incomplete gear. The incomplete gear and the modulation shaft rotate synchronously. When a toothed segment of the incomplete gear meshes with the toothed structure of the interference member, the interference member is adapted to be driven by the incomplete gear to move relative to the base.

The present invention further provides another window blind, which includes a headrail, a covering assembly, a lifting mechanism, a tilt mechanism, and an auxiliary unit. The covering assembly is provided below the headrail, wherein the covering assembly sequentially includes a plurality of slats and a bottom rail in a direction away from the headrail. The lifting mechanism includes a driving module and a lift cord assembly, wherein the driving module is provided in the headrail. The lift cord assembly includes a first cord and a second cord, wherein an end of the lift cord assembly is operably connected to the driving module, while another end thereof is connected to the bottom rail. The lift cord assembly is adapted to be driven by the driving module to be released or retracted, whereby to expand or fold the covering assembly. The tilt mechanism includes a modulation module and a ladder tape, wherein the modulation module is provided in the headrail. The ladder tape includes two warps. An end of each of the warps is operably connected to the modulation module, and another end thereof is connected to the bottom rail. The slats are positioned between the warps. The modulation module is adapted to drive the warps of the ladder tape to create a relative vertical movement below the headrail, whereby to drive the slats and the bottom rail to rotate, switching the slats between an open state, which allows light to pass therethrough, and a closed state, which blocks light. When the slats are in the open state, the slats and the bottom rail are parallel to each other, and the bottom rail in such state is defined to be at an initial position; when the slats are driven by the modulation module to be switched from the open state to the closed state, the bottom rail is tilted by a first angle relative to the initial position. The auxiliary unit is provided between the lifting mechanism and the tilt mechanism. When the bottom rail is tilted at the first angle, the auxiliary unit is adapted to be driven by the tilt mechanism, by which the lifting mechanism is concurrently motivated to further release the lift cord assembly, whereby the bottom rail is further tilted at a second angle relative to the initial position, wherein the second angle is greater than the first angle.

In an embodiment, when the lifting mechanism is concurrently motivated by the auxiliary unit to further release the lift cord assembly, the first cord and the second cord are synchronously released by a same length.

In an embodiment, the slats are positioned between the first cord and the second cord, and the first cord has a tension different from that of the second cord.

In an embodiment, when the bottom rail is tilted at the second angle, the bottom rail and the slats are parallel to each other.

In an embodiment, the auxiliary unit includes a timing transmission mechanism and a driven member. The timing transmission mechanism is connected to the modulation module to be driven by the modulation module. The driven member connects the driving module and the timing transmission mechanism, and the timing transmission mechanism operably drives the driven member.

In an embodiment, the modulation module includes a modulation shaft, around which the timing transmission mechanism is provided, and the timing transmission mechanism is rotatable along with the modulation shaft. When the bottom rail is tilted to the first angle, the driven member is adapted to be driven by the timing transmission mechanism, and the driving module is concurrently motivated by the driven member which is being driven, whereby to release the lift cord assembly.

In an embodiment, the driving module includes a cord reel and an actuating device which is concurrently motivated when the cord reel is driven. The lift cord assembly is adapted to be concurrently motivated by the cord reel. The actuating device is adapted to provide a motivating force to the lift cord assembly, wherein the motivating force is for retracting the lift cord assembly back into the headrail.

In an embodiment, the actuating device includes a driving drum, a spring-receiving drum, and a torsion spring. The torsion spring connects the driving drum and the spring-receiving drum. The driving drum and the cord reel are connected in a manner that they are adapted to be concurrently motivated by each other, whereby to provide the motivating force to the cord reel.

In an embodiment, the driven member includes a toothed structure provided on the driving module, and the toothed structure concurrently moves with the cord reel. While the toothed structure is being driven by the timing transmission mechanism to concurrently motivate the cord reel to release the lift cord assembly, the motivating force has to be overcome.

In an embodiment, the timing transmission mechanism includes an incomplete gear, which is provided corresponding to the toothed structure. The incomplete gear concurrently rotates with the modulation shaft. When the bottom rail is not tilted to the first angle yet, a toothed segment of the incomplete gear does not mesh with the toothed structure, so that the incomplete gear is adapted to independently rotate along with the modulation shaft relative to the toothed structure; when the bottom rail is tilted to the first angle, the toothed segment of the incomplete gear meshes with the toothed structure, so that the incomplete gear is adapted to be rotated along with a rotation of the modulation shaft, whereby to drive the toothed structure, which makes the cord reel rotate to further release the lift cord assembly, by which the bottom rail is further tilted to the second angle.

In an embodiment, the timing transmission mechanism further includes an auxiliary gear, which is freely rotatable relative to the modulation shaft, and always meshes with the toothed structure.

In an embodiment, the driving module further includes a transmission cord, which connects the cord reel and the lift cord assembly. The cord reel is adapted to be concurrently motivated by the actuating device to wind up or release the transmission cord, whereby to retract or release the lift cord assembly.

In an embodiment, the lifting mechanism further includes a movable seat assembly, which includes a movable seat and a positioning pin. The movable seat is movable in a longitudinal direction of the headrail, and the positioning pin is fixedly provided in the headrail. A segment of the lift cord assembly located in the headrail is arranged in a manner that runs back and forth between the movable seat and the positioning pin. An end of the transmission cord is connected to the movable seat, and another end thereof is connected to the cord reel. The cord reel is adapted to be concurrently motivated by the actuating device to retract or release the transmission cord, so that the lift cord assembly is, through the movable seat, concurrently motivated when the transmission cord is driven. When the driven member is driven by the timing transmission mechanism to concurrently motivate the cord reel to release the lift cord assembly, the motivating force provided by the actuating device has to be overcome.

In an embodiment, the driven member includes an interference device located between the cord reel and the lift cord assembly. The lifting mechanism further includes a movable seat assembly, which includes a movable seat and a positioning pin, wherein the movable seat is movable in a longitudinal direction of the headrail, and the positioning pin is fixedly provided in the headrail. A segment of the lift cord assembly located in the headrail is arranged in a manner that runs back and forth between the movable seat and the positioning pin. The transmission cord passes through the interference device, and has an end connected to the cord reel and another end connected to the movable seat. The cord reel is adapted to be concurrently motivated by the actuating device to retract or release the transmission cord, so that the lift cord assembly is, through the movable seat, concurrently motivated when the transmission cord is driven.

With the design mentioned above, the window blind provided in the present invention has the following advantages:

In summary, an auxiliary unit is further provided between the lifting mechanism and the tilt mechanism. When the covering assembly of the window blind is in the second state, i.e., when part of the covering assembly is unable to correspondingly rotate along with the relative vertical movement between two warps, the tilt mechanism could be further operated to drive the auxiliary unit to start operating. With the operation of the auxiliary unit, the lift cord assembly could be driven to be further released, which would eliminate the restriction imposed on the bottom rail by the length of the lift cord assembly, whereby the bottom rail could be further tilted by an angle. In this way, the covering assembly of the window blind could be changed into the first state again. In other words, with the presented invention, the covering assembly could be correspondingly rotated again along with the relative vertical movement created between two warps. As a result, when the window blind provided in the present invention is in the fully closed state, the region near the bottom rail would not have the problem of light leakage, and the desired shading area of the window would be in line with expectation. Therefore, an excellent light-blocking effect could be provided.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

