The following invention relates to lifting mechanisms for window coverings. More particularly, this invention relates to lifting mechanisms for window coverings which automatically provide sufficient lifting force so that a bottom rail of the window covering will remain in a position where it is placed by a user until the bottom rail is again moved by a user to a new position, without requiring manipulation of locking mechanisms, such as buttons, cords or other manually actuated locking mechanisms.
Window coverings are provided in a wide variety of styles and configurations to both provide the function of at least partially occluding the passage of light through a window and enhancing an appearance of a room in which the window is located. Such window coverings can include shades which are typically continuous from a top rail at an upper end of the window covering that is typically affixed adjacent an upper end of the window, to a bottom rail at a bottom end of the window covering. Such shades can be in the form of a single layer of material or multiple layers of material and can be pleated or smooth, and can optionally include cellular “hive-like” cavities within the window covering structure itself. Window coverings can also be in the form of blinds which are typically formed of separate slats of rigid or flexible material which either have a fixed angle or can be adjusted in angle to allow some light to pass through the separate slats within the blind. Any window covering with some form of bottom rail spaced from a top rail an adjustable distance, could benefit from this invention.
The entire assembly mounted within the window can be referred to as the window covering assembly. The portion of the window covering assembly which acts to occlude the passage of light can be referred to as the window covering material, whether continuous or not and whether flexible fabric or rigid slats or other elements. The entire window covering assembly thus includes the top rail, the bottom rail and the window covering material extending between the top rail and the bottom rail.
While window coverings can be of fixed size, window coverings are usually desirably adjustable so that the window can be blocked when desired or exposed (at least partially), depending on the needs of the user. Various different prior art window covering adjustment systems are known. Most typically, cords are provided which extend from the bottom rail, through the window covering structure up to the top rail, and then continue on an exterior side of the window covering structure. A user grasps the cords and pulls the cords to raise the bottom rail towards the top rail and expose the window. The user releases the cords and the weight of the bottom rail causes the window covering to cover the window. Often locking mechanisms are also provided to assist in locking the cords to fix the bottom rail of the window covering at a desired position.
Such external cord based window covering adjustment mechanisms are less than entirely satisfactory. The cords can become entangled with themselves or other structures, rendering the cords non-functional in adjusting the position of the window covering. The cords present a safety risk, especially for infants and toddlers. Also, the locking mechanisms for locking the cord in the desired position, so that the window covering bottom rail is positioned where desired, is often difficult to use effectively and is prone to wearing out, so that the window covering is effectively stalled in either the fully open or fully closed position.
The deficiencies in external cord systems for adjusting window covering position have led to the development of “cordless” window coverings. For instance, see U.S. Pat. No. 6,644,375. Such cordless window coverings include cords which are internal, extending between the top rail and the bottom rail, but with no external cords. Some such cordless blinds utilize locking mechanisms adjacent the top rail or the bottom rail which are typically in the form of buttons. When the bottom rail is to be raised to expose the window, one or more buttons are pushed and the bottom rail is raised. When the button(s) is released, the shade remains in the selected position. When the bottom rail is to be lowered, the button(s) can again be pushed and the bottom rail repositioned before releasing the button(s) with the bottom rail in the new desired position. In at least one window covering, included in U.S. Pat. No. 6,823,925, the bottom rail can be pulled down without requiring that the buttons be pushed. Only when the bottom rail is to be raised do the buttons need to be pushed.
Other prior art window coverings have height adjustment mechanisms which rely on some form of balancing of the bottom rail so that adjustment of the height of the shade is somewhat automatic. Instead of requiring that buttons be pushed, the bottom rail is merely repositioned to a desired position. The shade then remains balanced in the new position. For instance, see U.S. Pat. No. 6,571,853.
While such balanced cordless shades are taught in the prior art, such balanced cordless shades have heretofore required complex mechanisms which have exhibited various undesirable performance characteristics. In particular, such cordless balanced shades have typically included some form of cord collecting structure, such as a spool which has been biased, such as with a spring to cause the cord running from the bottom rail up to the cord collector to be encouraged onto the spool. As the bottom rail moves downward, the strength of the spring increases, making it difficult to cause the bottom rail to remain fixed in the lower position. At a minimum, the bottom rail is inclined to bounce somewhat and not remain solidly in a fully down position. When a weaker spring or other biaser is used, it has insufficient force to keep the bottom rail from falling down at least somewhat when the user desires that the window covering be entirely open. Also, such balanced cordless shades can wear over time in a way that causes them to not stay reliably where positioned, and can get positioned with the bottom rail non-horizontal.
Variable resistance springs have been attempted, as one solution to this problem. Various cord handling mechanisms have been utilized including one-way brakes and one-way cord movement retarders to discourage such undesirable bounce. With each of these solutions, a need remains for a simple and reliable lifting mechanism for a window covering which allows a user to easily adjust a position of the bottom rail of the window covering merely by grasping the bottom rail and positioning it where desired, with confidence that the bottom rail will remain precisely where it has been left until it is again moved by the user.
This invention provides a lifting mechanism for a window covering which facilitates a cordless window covering being easily positioned as desired and easily repositioned, by merely grasping and placing a bottom rail of the window covering where the user desires it to be. The window covering includes a top rail and a bottom rail with a window covering material supported therebetween. At least one cord (and typically two cords) extends between the top rail and the bottom rail. A cord collector is located within one of the rails with the cord coupled to the cord collector at the end of the cord adjacent the cord collector. The cord collector is coupled to a biaser which biases the cord collector in a direction encouraging the cord collector to collect the cord thereon. The cord is routed so that generally the weight of the shade counteracts the forces exerted by the biaser so that the cord remains stationary and hence the bottom rail of the window covering remains stationary, unless external forces are applied to the system.
It is desirable to keep tension on the cord to avoid slack and potential binding of the cord within the cord collector or otherwise internally within the window covering. However, it is also desirable to allow the cord to move freely during raising or lowering of the bottom rail of the window covering. These two goals are in conflict with each other. With this invention, a cord tension sensor is provided which senses the tension in the cord. When the tension in the cord is similar to that which is provided by gravity loads acting on the bottom rail and lower portions of the window covering, a high friction force is applied to the cord essentially locking the cord so that the bottom rail remains fixed. If forces acting on the bottom rail are increased or decreased, such as accompanying forces associated with a hand of a user gripping the bottom rail and raising or lowering the bottom rail, this change in tension in the cord is sensed by the cord tension sensor. The cord tension sensor then adjusts the variable resistance force on the cord to reduce or eliminate the cord resistance force so that the cord can move freely to be collected by the cord collector or released from the cord collector, as the bottom rail is raised or lowered by a user.
Additionally, a progressive resister is coupled to the cord collector. The progressive resister adds a progressive amount of resistance to motion of the cord collector as a greater amount of cord is taken away from the cord collector. Thus, when the bottom rail is most distant from the top rail and the cord is mostly off of the cord collector, the progressive resister exerts a maximum resistance force against collection of the cord by the cord collector, in effect resisting the action of the biaser upon the cord collector. When the bottom rail is closer to the top rail and a greater amount of the cord is collected with the cord collector, a relatively lesser amount of resistance is exerted upon the cord collector by the progressive resister, so that action of the biaser upon the cord collector is opposed to a lesser extent.
The action of the progressive resister allows the window covering to avoid the “bounce” phenomena associated with the biaser, such as a spring, exerting an excessive force upon the cord collector when the cord is a maximum amount away from the cord collector. Also, the progressive resister allows the cord collector to function similarly whether a large portion of the window covering material is being supported by the bottom rail (typically when the bottom rail is higher) or whether a small portion of the window covering material is being supported by the bottom rail (typically when the bottom rail is lower). As the bottom rail moves downward, more of the window covering material has its weight suspended from the top rail rather than held up by the bottom rail. The amount of resistance added by the progressive resister is thus correlated with the amount of cord collected with the cord collector and by correlation, the position of the bottom rail relative to the top rail.
When two cords are provided between the bottom rail and the top rail, preferably two cord collectors are provided with the two cord collectors preferably linked together so that they collect common amounts of cord simultaneously and release common amounts of cord simultaneously. Thus, the bottom rail remains parallel with the top rail at all times. A single progressive resister preferably acts upon both cord collectors.
In a most preferred arrangement, the cord collectors are in the form of spools with the biasers in the form of separate helical springs associated with each of the cord collectors. The spools are coupled to gears which mesh with each other and with a resistance gear coupled to the progressive resister.
While the progressive resister could take different forms, in a most preferred embodiment, the progressive resister includes a threaded shaft coupled to the resistance gear and with a bottom plate adjacent the resistance gear and a top plate spaced from the bottom plate. The top plate and bottom plate are preferably configured to avoid rotation and with the top plate coupled to a key with a threaded hole upon the threaded shaft so that the top plate moves toward and away from the bottom plate when the resistance gear rotates. A spring is interposed between the top plate and the bottom plate so that when the top plate moves toward the bottom plate, the spring is compressed and the bottom plate exerts a relatively greater amount of force against the resistance gear. The bottom plate thus resists rotation of the resistance gear and the other gears meshed therewith, including the gears coupled to the spools, a variable amount.
Accordingly, a primary object of the present invention is to provide a window covering without any external cords and which can be adjusted in height easily and reliably.
Another object of the present invention is to provide an adjustable height window covering which has a bottom rail which remains in a position in which it is manually placed and which can be easily moved by grasping the bottom rail and moving the bottom rail to the position where desired.
Another object of the present invention is to provide a “cordless” window shade which can be adjusted in height without requiring manual actuation of a locking mechanism.
Another object of the present invention is to provide a window covering which has a bottom rail which remains parallel with a top rail at all times and which bottom rail can be easily positioned where desired relative to the top rail.
Another object of the present invention is to provide a window covering which is both free of any external cords and balanced so that the bottom rail can be positioned where desired without requiring actuation of any locking mechanisms, and which bottom rail avoids a “bounce” phenomena throughout a range of motion of the bottom rail.
Another object of the present invention is to provide a window covering which does not have any external cords and which is balanced, and can be easily cut to different widths without interfering with lifting mechanism performance.
Another object of the present invention is to provide a window covering which is free of external cords and is balanced, and which exhibits reliable performance for a long duration and with heavy use.
Another object of the present invention is to provide a window covering which is free of external cords and balanced, and which can be readily manufactured from commonly available materials while still exhibiting reliable quality performance.
Another object of the present invention is to provide a method for controlling a position of a bottom of a window covering which is simple to use and performs reliably for all positions.
Another object of the present invention is to provide a method and apparatus for controlling friction on a moving cord based on tension sensed within the cord.
Other further objects of the present invention will become apparent from a careful reading of the included drawing figures, the claims and detailed description of the invention.
Referring to the drawings, wherein like reference numerals represent like parts throughout the various drawing figures, reference numeral 10 (FIGS. 1 and 3-5) is directed to a lifting mechanism for a window covering 2. The window covering 2 generally includes a top rail 4 parallel with and spaced from a bottom rail 6 with a window covering material structure extending between the top rail 4 and bottom rail 6.
Cords 8 extend between the top rail 4 and the bottom rail 6. The lifting mechanism 10 acts upon the cords 8 within one of the rails 4, 6 so that the bottom rail 6 can maintain equilibrium wherever the bottom rail 6 is positioned by a user. In this way, a user can raise the bottom rail 6 (arrow B of
In essence, and with particular reference to FIGS. 1 and 3-5, basic details of the lifting mechanism 10 are described. The lifting mechanism 10 is preferably located within a central portion of the bottom rail 6 of the entire window covering assembly. The cords 8 extend out of the lifting mechanism 10 in opposite horizontal directions to cord tension sensors 110 also within the bottom rail 6. The tension sensors 110 redirect the cords 8 from extending horizontally within the bottom rail 6 to extending substantially vertically up to the top rail 4.
The cords 8 interface with the lifting mechanism 10 through spools 30 which are configured to collect the cords 8 thereon and release the cords 8 therefrom, depending on the position of the bottom rail 6 relative to the top rail 4. Springs 40 are coupled to each of the spools 30. The springs 40 bias the spools 30 toward collecting the cords 8 upon the spools 30. The springs 40 thus attempt to counteract gravity forces acting upon the bottom rail 6 and tending to pull the cords 8 off of the spools 30.
A progressive resister 50 is provided which exerts progressively greater resistance to spool 30 rotation as progressively greater amounts of cord 8 are released from the spools 30. The progressive resister 50 thus acts against the forces exerted by the springs 40 upon the spools 30. This allows for enhanced shade positioning performance, such as to accommodate weight transfer from the bottom rail to the top rail as the bottom rail moves down. Preferably the progressive resister 50 is coupled to the spools 30 through a gear set 80.
More specifically, and with particular reference to
The top rail 4 is preferably a rigid elongate structure. The top rail 4 is configured so that it can be fastened to an upper portion of a casing S surrounding a window W. The top rail 4 suspends the entire window covering 2 assembly from the casing S. The top rail 4 can be fastened to the casing S with adhesive, with mechanical fasteners, or with other fastening methodologies known in the window covering arts. Two such fasteners are described in corresponding U.S. Published Patent Application Nos. 2006/0081746 and 2008/0011922. The top rail 4 can optionally include the lifting mechanism therein along with the cord tension sensor 110 pair, inverted to redirect cord from horizontal to vertically downward (
The bottom rail 6 is an elongate substantially rigid structure. The bottom rail 6 is preferably hollow so that the lifting mechanism 10 can be placed therein. The bottom rail 6 preferably includes the lifting mechanism 10 therein, but can optionally be vacant with the lifting mechanism 10 included in the top rail 4 (
The window covering material extending between the top rail 4 and the bottom rail 6 can be any of a variety of different window covering materials known in the art. For instance, the window covering 2 can be in the form of a continuous shade which is either pleated or unpleated, and can form either a single layer between the top rail 4 and the bottom rail 6 or include multiple layers. If multiple layers are included, these layers can be coupled together such that the window covering 2 takes on a cellular form with a “hive-like” cross-section. The window covering 2 could also be in the form of blinds made up of separate slats tethered together that may be fixed or rotatable to vary an amount of light passing therethrough.
At least one cord 8 extends between the top rail 4 and the bottom rail 6. Most preferably, two cords 8 are provided between the top rail 4 and the bottom rail 6. Optionally, more than two cords 8 could be provided. Each of the cords 8 is preferably substantially circular in cross-section and formed of a flexible woven textile material or a flexible plastic material such as nylon or polyethylene. Alternatively, the cords 8 could be in the form of metal chain, plastic chain, fabric chain, flexible tape, flexible ribbon, or any other flexible elongate structure suitable for suspending the bottom rail 6 from the top rail 4 and being handled by the various cord handling mechanisms of this invention. When the term cords is used, it is used generally to refer to any such elongate flexible structures.
The window covering material, top rail 4, bottom rail 6 and cords 8 together form the window covering 2 assembly which includes the lifting mechanism 10 according to this invention. The entire window covering 2 assembly is preferably configured to be readily adjusted in width to generally match a width of the casing S adjacent the window W. Specifically, the lifting mechanism 10 and the cord redirectors 20 are preferably located sufficiently near to a center of the window covering 2 assembly so that about half of the overall width of the window covering 2 assembly is between the cords 8 and about one-fourth of the window covering 2 assembly is on either side of the cords 8. The window covering material, top rail 4 and bottom rail 6 can thus be cut, typically with equal amounts being cut from each end of the window covering material, top rail 4 and bottom rail 6, to adjust to a width of the casing S down to nearly one-half of the original width of the window covering 2 assembly.
Numerous different window cutting methodologies and cutting tools can be utilized to facilitate such cutting, such as described below in conjunction with
With particular reference to
The housing 12 is an elongate rigid structure which supports the various different components of the lifting mechanism 10 to securely hold these components in precise position relative to each other to maximize desirable function for the lifting mechanism 10. The housing 12 thus includes a generally flat horizontal floor 14 with walls 16 extending perpendicularly up from front and rear sides of the floor 14. A cover 18 is separately provided which spans upper edges of the walls 16 to close the housing 12 (
The housing 12 preferably includes multiple holes through which various different components are supported. These holes include alignment holes 15 for maintaining alignment of the spools 30 and associated structures. The housing 12 also includes gear clearance holes 17 which allow the gears such as the spool gears 82 coupled to the spools 30 and the resistance gear 84 coupled to the progressive resister 50 to have a maximum diameter and to allow the housing 12 to be formed by bending the walls 16 up from the floor 14 without concern for any curvature where the walls 16 and floor 14 are joined together. An alignment hole 19 is further provided to maintain alignment of the progressive resister 50 relative to the housing 12.
Additional holes are provided on the housing 12 such as to facilitate the inclusion of the auxiliary springs 90 and associated equipment for the alternative embodiment of
With particular reference to
Gravity forces acting on the bottom rail 6 are converted into tension in the cord 8 when the bottom rail 6 is static. To keep the bottom rail 6 from moving downward under gravity loads, the progressive resister 50 acts on the cord collector, including the spools 30 and the associated biaser in the form of the springs 40, so that cord 8 does not come off of the spools 30 and the bottom rail 6 remains static.
Such a static position of the bottom rail 6 is further assisted by engagement of the cord 6 by the pawl 160 within the cord tension sensor 110. In particular, the bias spring 165 acts on the pawl 160 to rotate the pawl 160 counter-clockwise (about arrow Q of
Should the user desire to raise the bottom rail 6, the user grips the bottom rail 6 and lifts on the bottom rail 6. When this lifting force is encountered by the bottom rail 6, it is in a direction opposite gravity forces so that net forces downward on the bottom rail 6 are reduced. In turn, such reduction reduces tension on the cord 8 to a level which is less than cord collection forces applied by the biaser 40 acting on the spools 30 or other cord collectors, so that the spools 30 start to collect the cord 8, by motion of the cord 8 from the cord tension sensor 110 toward the cord collector, such as the spool 30 (along arrow B of
These forces applied by the biaser of the cord collector are sufficiently strong to counteract forces applied by the bias spring 164 within the tension sensor 110, so that the pawl 160 rotates in a counter-clockwise direction slightly (along arrow L of
Most typically, engagement surface 162 still drags slightly against the cord 8 when in this condition, but any friction forces applied by the pawl 160 on the cord 8 are less than the strength of the biaser within the cord collector which is drawing the cord 8 onto the spools 130 or other cord storage space within the cord collector. Such movement of the cord 8 past the pawl 160 (along arrow B of
Should a user desire to lower the window covering 2, the user grasps the bottom rail 6 and applies a downward force on the bottom rail 6. This downward force acts in addition to gravity forces so that tension on the cord 8 is greater than tension associated with gravity forces alone. The compression spring 150 is selected so that it cannot be compressed when tension forces on the cord 8 are those associated with gravity forces alone. However, when additional downward forces are applied and the tension in the cord 8 exceeds the tension associated with gravity forces alone, the compression spring 150 is compressed (along arrow P of
Along with such compression, the lever 140 is caused to rotate in a counter-clockwise direction (about arrow N of
When a user has positioned the bottom rail 6 where desired, the user need merely stop pulling down on the bottom rail 6. At this point only gravity loads are again acting on the bottom rail 6 and the lever 140 rotates clockwise back to its original position (
As described in detail below, gravity forces acting on the bottom rail 6 are not necessarily merely the weight of the bottom rail 6, but also can include some portion of weight of window covering material between the top rail 4 and the bottom rail 6. To account for this variable gravity force for different positions of the bottom rail 6, the progressive resister 50 provides a variable amount of resistance to cord collector forces acting on the cord 8, so that the window covering 2, 102 functions in a similar manner whether the bottom rail 6 is near a bottom of a window covering space or near a top of a window covering space.
While the tension sensor 110 has been disclosed for use in conjunction with the lifting mechanism 10, it is conceivable that the lifting mechanism 10 could be replaced with some other lifting device, such as a motor. Such a cord tension sensor 110 could still be utilized. In such a system, the cord tension sensor would help to detect whether the motor is in a cord collection or cord release mode (or static) and add friction, reduce friction or lock the cord accordingly when such a motorized lifting mechanism is idle.
With particular reference to
Most preferably, two spools 30 or other cord collectors are provided, with each of these spools 30 coupled to a separate one of the two cords 8 of the preferred embodiment. It is conceivable that a single spool 30 could be coupled to a single cord 8 or that a single spool 30 could simultaneously gather two or more cords 8 and still function according to this invention. Also, more than two spools 30 could be provided and more than two cords 8.
Other forms of cord collectors which can function as a means to collect cords within the lifting mechanism 10 of this invention could include cord gathering cavities into which the cord 8 could be fed and released without winding of the cord, or multiple axle cord collection spindles, or other components capable of gathering up the cord 8 and containing the cord 8 in a defined region until the cord 8 is to be released.
According to the preferred embodiment, each of the spools 30 includes a central post 32 rigidly coupled thereto. The post 32 includes a slit 33 therein for connection to an associated spring 40 or other biaser, discussed in detail below. The spools 30 include an upper wall 34 spaced from a lower wall 35, with each of the walls 34, 35 defining portions of the spools 30 which extend radially away from the post 32 and a rotational central axis of the spools 30, a greater amount than other portions of the spools 30. A space between the walls 34, 35 defines a cord collection region for the spool 30. The walls 34, 35 keep the cord 8 from working its way off of the spools 30 and becoming entangled within other portions of the lifting mechanism 10.
A lower bearing 36 is provided with a generally doughnut shape and which supports a lower end of the post 32 in a rotating fashion. The lower bearing 36 preferably remains stationary, but could optionally rotate, and rests within a hole in the floor 14 of the housing 12 (
An upper bearing 37 adjacent the upper wall 34 separates rotating portions of the spool 30, including the upper wall 34, from portions of the spring 40 adjacent thereto, so that friction contact and associated resistance is minimized between the spool 30 and the adjacent spring 40. Gear screws 38 attach the spool gear 82 (described in detail below) to the lower wall 35 of the spool 30. Thus, the spool 30 and associated post 32 are caused to rotate along with the spool gear 82.
The springs 40 provide a preferred form of biaser for the spools 30 or other cord collectors. Preferably, one spring 40 is provided for each spool 30. However, multiple springs 40 can be provided for each spool 30, or a single spring 40 could be provided for multiple spools 30. The springs 40 act as a preferred form as a means to bias the spools 30 or other cord collection means toward collecting more of the cord 8 upon the spool 30. Thus, the springs 40 tend to cause the cord 8 to be wound up onto the spools 30.
Countervailing forces including the weight of the bottom rail 6 and associated components located within the bottom rail 6, as well as friction with elements of the system, counteract this biasing force of the spring 40. The bottom rail 6 of the window covering 2 assembly thus remains stationary in a position where it is placed by a user, unless a user adds a lifting force upward (along arrow B of
While the springs 40 provide a preferred form of biaser, other forms of biasers could similarly be utilized to provide a means to bias the spool 30 or other cord collector toward collecting more of the cord 8. For instance, the biaser could be in the form of a resilient structure such as a rubber band. The biaser could also be in the form of various different configurations of springs, rather than merely the helical spring 40 of the preferred embodiment.
The spring 40 of the preferred embodiment resides within a cavity 42 which acts as a housing for the spring 40 to keep the workings of the spring 40 from being obstructed. The cavity 42 includes a generally flat floor 43 with a post hole 44 therein which allows the post 32 to extend up through the cavity 42. The cavity 42 additionally includes sides 45 which are generally cylindrical in form facing the cavity 42.
A gap 46 is formed in one of the sides 45. This gap 46 helps to anchor one end of the spring 40 in a stationary fashion while an opposite end of the spring 40 is coupled to the post 32. Specifically, the spring 40 is preferably in the form of a helical spring having an outer tab 47 at an outermost end of the spring 40 and an inner tab 48 at an innermost end of the spring 40. The outer tab 47 is configured to pass through the gap 46 and be secured to the cavity 42 structure.
Because the cavity 42 is generally square in form, it is not capable of rotating within the housing 12 (
The inner tab 48 is oriented within the slit 33 in the post 32. Hence, when the spool 30 rotates and the post 32 rotates along with the spool 30, the inner tab 48 of the spring 40 is also caused to rotate. Such rotation of the inner tab 48 causes the spring 40 to be wound up or wound down, depending on the direction of rotation of the spool 30. In this way, the spring 40 acts according to the preferred embodiment to bias the spool 30 or other cord collector toward collecting greater and greater amounts of the cord 8 upon the spool 30 or other cord collector.
With particular reference to
The progressive resister 50 of the preferred embodiment preferably is provided as a single unit which acts upon a pair of spools 30 with each of the spools 30 acting upon a separate one of two cords 8 within the window covering assembly. Alternatively, a single progressive resister 50 could act upon a single spool 30 or other cord collector in a single cord version of the window covering assembly. Similarly, multiple progressive resisters 50 could be provided acting upon a single spool 30 or upon multiple spools 30. In embodiments where multiple progressive resisters 50 are utilized, each spool 30 can have its own progressive resister 50. The multiple spools 30 can either be linked together by gears or otherwise, or the spools 30 can be independent of each other.
The progressive resister 50 according to the preferred embodiment includes a base bearing 52 which supports other portions of the progressive resister 50 above the floor 14 of the housing 12. The base bearing 52 preferably extends at least partially into a hole in the floor 14 of the housing 12 (
The base bearing 52 includes a bore 54 in an upper end thereof. The bore 54 is aligned with a central axis of the base bearing 52 and supports a threaded shaft 55 of the progressive resister 50 extending vertically up from the bore 54 of the base bearing 52. Particularly, the threaded shaft 55 preferably includes a lower tip 56 which extends down into the bore 54. An upper tip 57 of the threaded shaft 55 extends into the alignment hole 19 and the cover 18 of the housing 12 (
The lower tip 56 of the threaded shaft 55 can be keyed and have a contour matching that of the bore 54 so that the threaded shaft 55 rotates with the base bearing 52. Alternatively, or in addition a fastener can be utilized to secure the lower tip 56 of the threaded shaft 55 within the base 24. When the base bearing 52 is fastened to the resistance gear 84 with the bearing screw 53 (
Alternatively, the lower tip 56 of the threaded shaft 55 can rotate relative to the bore 54. In such an embodiment (
A bottom plate 60 of the progressive resister 50 is oriented directly adjacent the resistance gear 84. The bottom plate 60 provides a preferred form of brake with a lower surface of the bottom plate 60 abutting the resistance gear 84 and with this abutment imparting a resistance force against free rotation of the resistance gear 84, which is proportional to a force with which the bottom plate 60 is pressed against the resistance gear 84. The bottom plate 60 has a generally square form so that it is prevented by the walls 16 of the housing 12 from rotating. Hence, the bottom plate 60 does not rotate along with the resistance gear 84 and the threaded shaft 55.
The bottom plate 60 includes a center hole 61 through which the threaded shaft 55 is allowed to pass without contact or obstruction. A recess 62 is preferably formed in an upper surface of the bottom plate 60. The recess 62 facilitates support of a compression spring 65 adjacent the upper surface of the bottom plate 60. A perimeter 64 of the recess 62 is generally cylindrical and has a diameter similar to a lower portion of the compression spring 65. Thus, the compression spring 65 is held within the recess 62 and is prevented from translating laterally relative to the bottom plate 60 and other portions of the progressive resister 50.
The compression spring 65 includes an upper end spaced from a lower end 68. The lower end 68 abuts the bottom plate 60 within the recess 62. The upper end 66 abuts a top plate 70 of the progressive resister 50. The compression spring 65 is preferably generally helical in form and particularly configured so that a spring force of the compression spring 65 increases as the compression spring 65 is compressed between the upper end 66 and the lower end 68, such as by moving the top plate 70 toward the bottom plate 60.
To maximize a degree of travel between the upper end 66 and the lower end 68, the compression spring 65 can be slightly conically tapered with the upper end 66 having a slightly smaller diameter than the lower end 68. In this way, the compression spring 65 can be collapsed with turns in the compression spring 65 being progressively inboard of each other and maximizing a degree of collapse which can be experienced by the compression spring 65. Alternatively, the compression spring 65 could be replaced with other forms of springs or resilient structures which would be capable of exerting a force down upon the bottom plate 60 when the top plate 70 is lowered against upper portions of the force applying structure.
The top plate 70 is generally planar with a lower surface of the top plate 70 adapted to abut the upper end 66 of the compression spring 65. A center hole 71 passes through the top plate 70, allowing the threaded shaft 55 to pass therethrough. The top plate 70 preferably includes a depression 72 therein which is shaped to support a threaded key 75 within the top plate 70. Alternatively, a threaded key 75 can be integrally formed with other portions of the top plate 70. The depression 72 is sized to allow the threaded key 75 to fit snugly therein so that the threaded key 75 and top plate 70 act together as a single unit. By making the threaded key 75 from a separate structure from other portions of the top plate 70, the threaded key 75 can be formed of a harder material than the top plate 70 to maximize performance of the top plate 70 and coaction with the threaded shaft 55.
The top plate 70 includes arms 74 which extend away from the center hole 71 and are adapted to abut the walls 16 of the housing 12. The top plate 70 is thus held by the arms 74 so that the top plate 70 cannot rotate. Rather, the top plate 70 can only translate vertically along a central axis of the threaded shaft 55.
The threaded key 75 includes a perimeter contour 76 matching that of the depression 72 so that the threaded key 75 fits securely within the depression 72. A threaded hole 78 passes through the threaded key 75. The threaded hole 78 includes threads therein which match a pitch of the threaded shaft 50.
To maximize a range of travel of the top plate 70, the threaded shaft 55 and threaded key 75 preferably have a very shallow pitch to their corresponding threads. When the resistance gear 84 rotates, the threaded shaft 55 rotates along with the resistance gear 84. The threaded key 75 translates vertically (along arrow H of
When such rotation is in a direction causing the top plate 70 to move toward the bottom plate 60, the compression spring 65 is compressed a greater and greater amount. As the compression spring 65 is compressed, it exerts a progressively greater force vertically down upon the bottom plate 60. The bottom plate 60 is thus urged with greater and greater force against the resistance gear 84. This in turn makes it progressively more difficult for the resistance gear 84 to rotate along with the spool gear 82 coupled to the spool 30.
With particular reference to
In the preferred embodiment, the spool gears 82 preferably rotate in a common direction (about arrows G and E of
While the gear set 80 provides the preferred form of coupling the progressive resister 50 to the spools 30, other forms of coupling could be provided. For instance, the progressive resister 50 could act directly upon the spools 30. For instance, in place of the springs 40, a progressive resister 50 could press directly against the upper wall 34 of the spool 30 through the bottom plate 60 so that resistance to spool 30 rotation would result. In such an arrangement, the springs 40 or other biasers would still need to be coupled to the spools 30 so that appropriate biasing forces tending to collect cord 8 upon the spool 30 would be provided. Options for such spring coupling including placement radially inboard of the spool 30 (as in the alternative spool 230 of
The gear set 80 advantageously links the spools 30 together so that in window coverings 2 with two or more cords 8, the cords 8 are gathered in equal amounts onto the spools 30 and the bottom rail 6 remains horizontal and parallel to the top rail 4. Such linking is not required however. Also, linking of the spools 30 as well as other components could be provided with alternative means to link the components together. For instance, belts, chains, sprockets, shafts and other mechanical couplings could be utilized to link the components together.
If sufficient height were available within the rails 4, 6 housing the lifting mechanism 10, it is conceivable that both the spools 30, springs 40 and progressive resisters 50 could all be stacked together vertically. If a particularly low profile rail 4, 6 is desired, the spools 30, springs 40 and progressive resisters 50 could all be laterally spaced from each other and geared together to an appropriately modified gear set 80. If the progressive resister is to be shortened to less than an overall height of the rails 4, 6 in which the lifting mechanism 10 is located, multiple progressive resisters 50 could be provided and configured so that progressively greater and greater resistance would be provided through multiple separate progressive resisters 50 having a shorter overall profile.
With particular reference to
Each auxiliary spring 90 includes a housing 92 generally similar to the cavity 42 for the springs 40 of the preferred embodiment. Each auxiliary spring 90 includes an outer end 94 spaced from an inner end 95 which can coact with posts 32′ including slits 33′ coupled to auxiliary spring gears 98. The housings 92 generally define deep cavities 96 in which the auxiliary springs 90 are located.
In this embodiment the auxiliary springs 90 have generally twice the height of the springs 40 of the preferred embodiment. Hence, significantly greater biasing forces can be provided when the auxiliary springs 90 are added to the lifting mechanism 10′. Auxiliary spring bearings 99 allow the auxiliary spring gears 98 to float slightly above the floor of the housing 12 to allow the auxiliary spring gears 98 to freely rotate. The spool gears 82 rotate in a similar direction to that of the preferred embodiment. however, the auxiliary gears 98 rotate in an opposite direction (along arrows I and J of
The auxiliary springs 90 provide significantly greater force tending to cause the spools 30 to collect the cords 80 thereon. Such an arrangement is desirable in situations such as where the window covering 2 is formed of an exceptionally heavy window covering material so that additional lifting force and cord collection force is required to balance the weight of the window covering 2. Similarly, if a heavy bottom rail 6 is provided, or if the entire window covering assembly is configured for use in an exceptionally tall window W (
With particular reference to
Placing the lifting mechanism 100 within the top rail 4 allows the bottom rail 6 to have a smaller configuration. Preferably, when the bottom rail 6 has a lower profile, the bottom rail 6 is provided with sufficient weight so that gravity forces tending to pull the cords 8 out of the cord collector are sufficient to overcome the biasing forces, such as those provided by the springs 40, to keep the lifting mechanism 10 in appropriate equilibrium. In addition to adding weights to the bottom rail 6, or as an alternative thereto, the springs 40 or other biasers can be provided with a lighter force. Additionally, resistance added to the system through the tensioners 110 (
With particular reference to
Before applying this downward force, the bottom rail 6 is in equilibrium. Particularly, the lifting mechanism 10 has a portion of the cord 8 wound upon the spools 30. The springs 40 are applying a force on the spools 30 tending to gather additional cord 8 onto the spools 30. A weight of the bottom rail 6 is acting through the pulleys 22 at the cord redirector 20, tending to cause the bottom rail 6 to move downward and causing the cords 8 to be played off of the spools 30.
These gravitational forces and spring 40 or other biasing forces are in equilibrium so that the spools 30 are at rest and the bottom rail 6 is at rest. Additionally, the progressive resister 50 as well as the tensioner 24 are adding additional resistance to cord 8 movement in either direction and spool 30 rotation in either direction to assist in maintaining equilibrium and stationary positioning of the spool 30.
When the user applies a downward force upon the bottom rail 6, this equilibrium is disturbed. Specifically, now both the gravitational forces acting downward on the bottom rail 6 and the forces applied by the user work together to overcome the biasing forces acting upon the spools 30 through the springs 40 and to overcome resistance forces applied by the tensioner 24 and the progressive resister 50. The bottom rail 60 moves down and cord 8 is played off of each of the spools 30.
As the bottom rail 6 moves downward (along arrow A of
So that a new equilibrium condition can be achieved by the lifting mechanism 10, the progressive resister 50 is provided which is progressive in nature. Particularly, with the bottom rail 6 in a lower position, and with more of the cord 8 played off of the spool 30, the springs 40 are applying a greater biasing force upon the spools 30. Also, to some extent a weight of the window covering 2 is partly suspended from the top rail 4 directly, rather than suspended through the bottom rail 6 and the cords 8.
Without the progressive resister 50, the bottom rail 6 would tend to bounce upward and not remain in a fully closed position covering the window W. However, with the progressive resistance 50 provided by the progressive resister 50, the progressive resister 50 is applying a progressively greater amount of resistance to spool 30 rotation as the cord 8 is played off of the spools 30. This resistance applied by the progressive resister 50 is thus sufficient to counteract the biasing forces applied by the springs 40 or other biasers upon the spools 30. Equilibrium is thus maintained when the bottom rail 6 is at the lower position.
When the user wishes to raise the bottom rail 6 (along arrow B of
While a user's hand is typically considered to be the control force which causes adjustment of the bottom rail 6 of the window covering assembly, other control forces could cause adjustment of the position of the bottom rail 6. For instance, an automatic window covering assembly could be provided where the bottom rail 6 would be raised or lowered by moving along a track, or by the action of separate cords coupled to a control mechanism such as a servo motor and a separate spool to position the bottom rail 6 where desired, such as through use of a remote control assembly. In such a configuration, the lifting mechanism 10 would sufficiently balance the window covering assembly so that a control mechanism could most easily manipulate the position of the bottom rail 6.
The progressive resister preferably provides progressively greater resistance along an entire range of motion of the cords 8 onto the spools 30 and off of the spools 30. The resistance force provided by the progressive resister 50 is preferably generally a linear function of the amount of cord upon the spool 30 and a generally linear function of the position of bottom rail 6 between the top rail 4 and a lowermost position spaced from the top rail 4. As an alternative, the progressive resister 50 could be configured so that it applies no resistance except when needed. For instance, the progressive resister 50 could be configured so that it provides no resistance until the bottom rail 6 is at a middle position, and then provides progressively greater resistance only for a lower half of bottom rail 6 travel. Similarly, the progressive resister 50 could provide progressively greater resistance in a non-linear fashion, such as proportional to a square of the amount of cord upon the spools 30 or other cord collectors. Some other function than a linear function could similarly be provided, with the goal being to allow the bottom rail 6 to remain in equilibrium and stationary at all positions for the bottom rail 6, between a lowermost position most distant from the top rail 4 and an uppermost position closest to the top rail 4. If a window covering 2 having a non-uniform weight distribution is provided, the progressive resister 50 can be appropriately configured to provide resistance when desired to maintain smooth operation of the lifting mechanism 10 for all different positions for the bottom rail 6.
The progressive resister 50 provides a degree of resistance to rotation of the spool 30 which is similar in both directions for the spool 30. Hence, whether the spool 30 is to rotate to gather additional cord 8 thereon or is to rotate to play additional cord 8 off of the spool 30, a similar amount of resistance is provided. The amount of resistance is correlated with the amount of cord 8 which is on the spool 30, which itself correlates with the position of the bottom rail 6 relative to the top rail 4. The progressive resister 50 thus provides resistance in a similar amount in both a lifting direction (along arrow B of
With further reference to
The internal spool spring 240 resides within a cavity 242 inboard of the alternative spool 230. Thus, the alternative spool 230 can have a greater height within a bottom rail 6 (or top rail 4) of fixed height. With such a taller alternative spool 230, a greater number of grooves in the grooved surface 237 can be provided, and a greater number of turns of the cord 8 can be provided before additional turns of the cord 8 need to stack upon previous turns of the cord 8. In typical window coverings, with this arrangement, the cord 8 need not stack upon previous turns of cord more than once or twice, such that a highly consistent amount of cord 8 is used up for repositioning of the window covering 2. Such consistent performance helps to keep the window covering 2 balanced with the bottom rail 6 parallel with the top rail 4 in window coverings 2 which have a pair of cords 8 therein.
With particular reference to
In essence, the tension sensor 110 of this preferred embodiment includes a base 120 in which various other portions of the tension sensor 110 are housed. A cavity 130 is formed extending down into the base 120. This cavity 130 includes contours to receive various different guide rollers 170 (
A pawl 160 is pivotably mounted within the cavity 130 of the base 120. The pawl 160 has an engagement surface 162 which can move into and out of contact with the cord 8 relative to a reference surface formed by a portion of a side wall 136 of the cavity 130. The pawl 160 is biased toward a position engaging the cord 8 somewhat. When high tension is sensed by the compression spring 150 and lever 140, the lever 140 pivots along with compression of the compression spring 150 sufficiently that the lever 140 abuts the pawl 160 and moves the engagement surface 162 of the pawl 160 into a position off of the cord 8 (
More specifically, and with particular reference to FIGS. 12 and 17-19, specific details of the base 120 are described, according to this preferred embodiment for the tension sensor 110. The base 120 is preferably a solid rigid unitary mass of material, such as an easily machinable or injection moldable long chain hydrocarbon plastic material. Alternatively, the base 120 could be formed out of aluminum or other metals. The base 120 is generally orthorhombic with parallel opposite side ends, parallel front and rear sides, and a top surface 124 opposite and parallel with a bottom surface. The side walls 122 are perpendicular to the top surface 124. A slit 126 is formed in one of the end outside walls 122 to allow the cord 8 to pass into the tension sensor 110. The cord 8 also accesses the cord sensor 110 through the top surface 124.
With continuing reference to FIGS. 12 and 17-19, details of the cavity 130 are described according to this preferred embodiment for the tension sensor 110. The cavity 130 is a recess formed down into the top surface 124 of the base 120. The cavity 130 includes a floor 132 which is preferably generally parallel with the top surface 124 of the base 120, but recessed from the top surface 124 by a height of side walls 136 of the cavity 130. Roller pins 134 extend vertically up from the floor 132. These roller pins 134 support various ones of the guide rollers 170 (
One of the side walls 136 includes a spring hole 138 therein which extends horizontally perpendicular to a surface of the side wall 136. This spring hole 138 is located to receive one end of a spring 165 which biases the pawl 160 to rotate in a clockwise direction about the pawl pin 167. The pawl 160 is thus biased toward maximum friction engagement, by the engagement surface 162 of the pawl 160, against the cord 8 and toward the reference surface provided by the side wall 136 of the cavity 130.
The cavity 130 also includes a trough 133 (
The cavity 130 also includes an entry alcove 135 in which a first roller 171 can be received in a unique orientation 90° away from the orientation of the other guide rollers 170. A circular chamber 139 is provided adjacent the entry alcove 135 which receives a second roller 172 therein, for further handling of the cord 8. A middle alcove 137 is located adjacent the circular chamber 139 and is generally elongate in form and supports the compression spring 150 therein, as well as roller 173.
Remaining portions of the cavity 130 generally support the pawl 160 and remaining rollers 174, 175 for routing of the cord 8 therethrough and between the engagement surface 162 of the pawl 160 and the reference surface formed by a portion of the side wall 136 of the cavity 130.
With particular reference to FIGS. 12 and 14-19, details of the lever 140 are provided according to a preferred form of the tension sensor 110 of this invention. The lever 140 is a rigid structure pivotably attached to the base 120 at a pivot end 142. A free end 143 of the lever 140 is opposite the pivot end 142 and abuts the compression spring 150. When the compression spring 150 is compressed by enhanced cord tension, the lever 140 pivots in a counter-clockwise direction about the lever pin 141. The lever 140 thus acts (along with the spring 150) as a form of tension sensing element within the tension sensor 110. Other forms of cord 8 tension sensing devices could alternatively be utilized, such as strain gauges.
The lever 140 converts this sensed tension into an activating force acting on the pawl 160 to deactivate the pawl and reduce variable friction forces applied by the pawl 160 on the cord 8. Activation of a pawl 160 by the lever 140 only occurs when high tension is sensed by compression of the compression spring 150 and pivoting of the lever 140. Thus, the lever 140 acts as a primary portion of a variable friction force control system that regulates cord 8 friction response to cord 8 tension.
The lever 140 preferably includes a bend 144 between the pivot end 142 and the free end 143 that is substantially 90°. At this bend 144 a pin 145 extends parallel with the lever pin 141. This pin 145 supports the guide roller 173 thereon. Through this roller 173 the cord 8 is engaged by the tension sensor in the form of the lever 140 and spring 150.
A side of the lever 140 opposite the compression spring 150 preferably includes a bumper 146 thereon. This bumper 146 is adapted to abut portions of the side walls 136 of the cavity 130 adjacent the lever 140, to keep the lever 140 from rotating too far in a clockwise direction and keeping the guide roller 173 mounted on the pin 145 from impacting this side wall 136, so that the guide roller 173 can maintain free rolling operation. As an alternative, this roller 173 can be allowed to drag on the side wall 136 at least a small amount should an increase in cord mount friction be desirable. The pivot end 142 of the lever 140 preferably includes a pin hole 147 which mounts upon the lever pin 141 to allow for rotation of the lever 140 relative to the base 120. An inside surface 148 of the lever 140 is provided opposite the bumper 146. This inside surface 148 selectively abuts a portion of the pawl 160 and causes the pawl 160 to rotate in a counter-clockwise direction when the lever 140 rotates in a counter-clockwise direction, due to compression of the compression spring 150 corresponding with increased tension in the cord 8.
With particular reference to
The compression spring 150 includes a first end 151 which abuts against the free end 143 of the lever 140. A second end 152 opposite the first end 151 abuts a portion of the side wall 136 of the cavity 130. The central axis of the compression spring 150 is generally aligned with the pin 145 on the lever 140 and extends perpendicular to a direction of cord 8 motion past the central axis of the compression spring 150. As the cord 8 passes over the guide roller 173 mounted on the pin 145 of the lever 140, if the cord 8 tension is elevated above a preselected amount, the compression spring 150 will be compressed somewhat, causing the lever 140 to rotate in a clockwise direction (arrow N of
With particular reference to FIGS. 12 and 14-19, particular details of the pawl 160 are described, according to this preferred embodiment of the cord tension sensor 110 of this invention. The pawl 160 is a substantially rigid mass pivotably mounted relative to the base 120. The pawl 160 can pivot about the pawl pin 167 and move the engagement surface 162 toward and away from a reference surface formed by a portion of the side walls 136 of the cavity 130 of the base 120.
The pawl 160 includes a notch 163 in the engagement surface 162 in at least some embodiments which tends to keep the cord 8 aligned near a middle of the engagement surface 162. This notch 163 can be open on a lower portion thereof (as particularly shown in
Portions of the engagement surface 162 above the notch 163 can abut the side wall 136 of the cavity 130, such as when the cord 8 is locked (
The pawl 160 includes a pivot hole 166 which rides on the pawl pin 167. A bias spring 165 is oriented with a central axis thereof aligned with the top surface 124 of the base 120 and the floor 132 of the cavity 130. This bias spring 165 biases the pawl 160 toward rotation in a clockwise direction (arrow Q of
The pawl 160 includes an abutment tip 168 on a portion thereof adjacent the lever 160. This abutment tip 168 comes into contact with the lever 140 when the lever 140 rotates counter-clockwise (arrow N of
With particular reference to
In a preferred embodiment, the guide rollers 170 are each generally include a central hole which acts as a bearing which rides upon a cylindrical pin such as the roller pins 134, or the pin 145 on the lever 140. One exception is the first guide roller 171 which is oriented with a central axis perpendicular to central axes of the other guide rollers 170. Preferably, the entry alcove 135 and the cavity 130 includes additional slots which allow portions of the roller 171 to act as a form of axle to keep the first roller 171 aligned therein. Some form of cap (not shown) or a portion of the top of the bottom rail 6 (or top rail 4) can be provided to keep the first roller 171 down within the entry alcove 135. The second guide roller 172 resides within the circular chamber 139. The third guide roller 173 is mounted on the pin 145 on the lever 140 and adjacent the middle alcove 137 of the cavity 130. The fourth guide roller 174 and fifth guide roller 175 are located on opposite sides of the pawl 160 and route the cord 8 between the engagement surface 162 of the pawl 160 and the reference surface provided by a portion of the side walls 136 of the cavity 130. Each of the guide rollers 170 preferably includes a notch centrally thereon to keep the cord 8 generally in a plane parallel with the top surface 124 of the base 120 and at a midpoint between the top surface 124 and a bottom surface opposite the top surface 124.
With particular reference to
The bobbining roller 180 is free to travel up and down on the sliding post 182. As cord 8 is stacked on the spool 30 (preferably including grooves thereon as shown in
Furthermore, such stacking is further inhibited by the contact roller 250, shown in detail in
With particular reference to
In this embodiment, the top rail 204 includes a measuring guide 205 adjacent each end of the top rail 204. These measuring guides 205 are preferably mirror images of each other, such as with similar graduation lines thereon and indicia adjacent at least some of the lines indicative of width for the window covering 102. Ends of the measurement guide 205 are preferably adjacent ends of the top rail 204.
Indicia adjacent graduation lines at these ends of the measurement guides 205 preferably identify a length similar to that of the top rail 204. Most preferably, such end indicia represent a width of the top rail 204 plus a clearance amount, such as one-quarter inch. In this way, when a user measures a width of a window (e.g. a measurement of thirty-six inches) and when the window covering is cut at a graduation line adjacent the corresponding indicia (the one that identifies “thirty-six inches”) at each end of the window covering 102, the window covering ends up with a width of thirty-five and three-quarters inches. Thus, a one-eighth inch clearance amount is provided at either side of the window covering (when it is mounted within a thirty-six inch wide window). Such a clearance amount is also useful in that many window spaces are not perfectly uniform in width. In this way, a user need merely measure the window and then cut the window covering at each end at graduation lines of the measurement guide 205 which have indicia adjacent thereto which match the width of the window.
Cutting typically occurs with a cutting tool, such as the cutting tool 210 which preferably has a fine serrated edge for cutting of various different fabrics or other materials which form the window covering material between the top rail 204 and bottom rail 206, without snagging or other cutting defects. After such cutting, the window covering 102′ has taken on a shorter length including two excess ends 104 which can then be discarded. End caps 202 are provided on ends of the window covering 102. These end caps 202 can be removed and preferably have just a friction fit over ends of the bottom rail 206. These end caps 202 can be replaced upon remaining portions of the window covering 102′ (
The bottom rail 206 in this embodiment includes the lifting mechanism 10 and tension sensor 110 (
Shrink tubing 200 is preferably provided outboard of the foam 190. This shrink tubing 200 is formed of a material which shrinks when heat is applied. Thus, the tubing goes from being somewhat loose outboard of the foam 192, to tightly bonding to or pressing against an exterior of the foam 190. The shrink tubing 200 thus acts as a “skin” on the foam 190 and resists cracking or bending failure of the foam 190 and generally adds additional strength to the foam 190, so that the bottom rail 206 has sufficient strength and yet still exhibits lightweight characteristics. This strength can be further enhanced by interposing an adhesive between the foam 190 and the shrink tubing 200. While portions of the foam 190 are exposed by the cutting procedure, the end cap 202 conceal portions of the foam 190 exposed by the cutting procedure.
Typically, the shrink tubing 200 would entirely surround the foam 190 and also surround central portions of the bottom rail 206 containing the lifting mechanism 10 and tension sensor 110. A hole would then be formed in the shrink tubing 200 for passage of the cord 8, and a lowermost portion of the window covering material would be bonded to the shrink tubing 200 on an upper side of the bottom rail 206. Thus, even though the bottom rail 206 has some portions which include mechanisms therein and other portions which are merely filled with foam 190, the entire bottom rail 206 has a consistent appearance between the ends.
While the shrink tubing 200 is shown as one form of outer skin on a foam 190 core forming the bottom rail 206 or other portion of the window covering, other forms of skins could also be provided on such a cuttable foam material for one of the rails (or all of the rails) of a window covering. For instance, adhesive tape could be applied to the foam, spray-on material such as a paint or other material could be applied that then hardens into a skin similar to the shrink tubing 200.
Furthermore, while the foam 190 and shrink tubing 200 is disclosed with regard to the particular type of window covering assembly 2, 102 disclosed in this invention, such a foam core with outer skin type rail could be provided for other forms of window coverings known in the prior art, including blinds and various different forms of pleated shades.
In addition to variations in the number of cords 8 contained within the window covering assembly 2, 102, it is also conceivable that more than two rails could be provided with the window covering. For instance, it is conceivable that a window covering could be provided with a top rail, a bottom rail and at least one intermediate rail. The window covering material would typically extend between the bottom rail and the intermediate rail. Two separate lifting mechanisms could be provided acting on different cords, for instance with one in the bottom rail and one in the intermediate rail (or one in the top rail and one in one of the other rails). The bottom rail would utilize one lifting mechanism either in the bottom rail or in the top rail, with a function as described elsewhere herein.
An intermediate rail is secured to upper portions of the window covering material through the lifting mechanism either within the intermediate rail or within the top rail. The intermediate rail could be moved up or down independently of the bottom rail and on separate cords. Thus, a gap could be provided between the top rail and the intermediate rail to allow light to pass through an upper portion of the window while a lower portion of the window is occluded at least partially by the window covering material suspended between the intermediate rail and the bottom rail. In any such three (or more) rail configuration, a lifting mechanism would be provided for each cord where the cord extends from a fixed end to a lifting mechanism. In such a multiple rail shade, portions of the window covering might include multiple cords adjacent thereto and the intermediate rail might include holes passing therethrough to allow cords associated with the bottom rail to pass through the intermediate rail on its way up to the top rail. As an alternative, the cords suspending the bottom rail might only be between the bottom rail and the intermediate rail.
This disclosure is provided to reveal a preferred embodiment of the invention and a best mode for practicing the invention. Having thus described the invention in this way, it should be apparent that various different modifications can be made to the preferred embodiment without departing from the scope and spirit of this invention disclosure. When structures are identified as a means to perform a function, the identification is intended to include all structures which can perform the function specified. When structures of this invention are identified as being coupled together, such language should be interpreted broadly to include the structures being coupled directly together or coupled together through intervening structures. Such coupling could be permanent or temporary and either in a rigid fashion or in a fashion which allows pivoting, sliding or other relative motion while still providing some form of attachment, unless specifically restricted.