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This application claims benefit of provisional patent application Ser. No. 61/357,252, filed Jun. 22, 2010. 
    
    
     TECHNICAL FIELD 
     The present invention relates to means for raising and lowering coverings for windows and other openings, in particular, to means for rotating a roller to which is fastened shade or the like. 
     BACKGROUND 
     Shades used for covering window openings and the like are commonly raised and lowered, to change the extent of blockage of an opening, by winding and unwinding—or reeling and unreeling, the shade on a roller. In the past, a roller has been driven in various ways, including by having a manually driven shaft, called a wand here, which is connected to the roller by a universal joint, a flexible shaft, a gear box and so forth. A universal joint (also called a U-joint) is a familiar mechanical fitting which allows the axis of a rotatable driving member to be offset from the axis of the driven member. U.S. Pat. No. 1,744,686 of Pease shows a relatively crude universal joint comprising two interlaced loops, for driving a gear system of a roller. U.S. Pat. No. 7,204,292 of Nien shows a universal joint in combination with a worm gear which drives a roller. 
     Particularly when the fabric of a shade is heavy, the weight of the hanging-down portion of the shade can cause the roller to turn, thus allowing the shade to unwind from its desired set position. Such kind of motion is sometimes referred to here as counter-rotation. Counter rotation can be resisted when there is a universal joint connected to the roller. If a wand or other driver which is connected to the joint is put at a sharp offset angle to the axis of the roller then the weight of the wand or slight holding force applied to it will resist rotation at the joint. 
     Another option is to interpose a gear box, for instance a worm gear box, between the wand and roller, because such a system by its nature resists counter rotation. Another way is to lock a wand against counter-rotation when there is only a flexible shaft connecting the wand and the roller. For example, the wand can be fastened to a window frame. Still another way is to make the handle-end of the wand hinged, so it can form a crank end that extends at an angle to the length of the rest of the wand; and the crank end may contact a window frame or a fitting or the shade itself. 
     However, there are situations in which it may be undesirable to have an element on the window frame to which the handle of a wand attaches, or to have a wand which has a crank end. Gear boxes may be expensive or slow down the speed at which the roller may be driven. When a universal joint is not well-aligned, i.e., when the driver is at a substantial angle to the driven parts, it may require a lot of force to turn the roller, and the motion can be unsmooth and difficult to the user. 
     Improved ways are still being sought, to simplify and improve the operation of a window treatment which is raised and lowered. 
     SUMMARY 
     An object of the invention is to provide a means for lifting a window treatment which prevents reverse rotation or unrolling of a shade or other window treatment part. A further object of the invention is to have a drive system for a lift-type window treatment which is easy to use and economic to construct. 
     In accord with an embodiment of the invention, a window treatment shade assembly comprises a shade which is alternately raised and lowered by reeling and unreeling the shade from a roller. The roller is rotated by a drive assembly which is connected to an end of the roller. The drive assembly is comprised of a flexible shaft connected to the roller; a universal joint connected to the flexible shaft; and, a means for rotating the universal joint, such as a wand, connected to the universal joint. Preferably, the universal joint is specially configured, and it is comprised of mating knuckles, each of which has a link with a slot; each link is engaged within the slot of the mating link. In a variation of the foregoing, a lifting member connected to a shade, such as a Roman shade, winds around the roller. 
     In exemplary use of the invention, the flexible shaft is spring-like and tends to bias the driven end of the universal joint toward the horizontal rotational axis of the roller. When the driven end of the universal joint is in such a location, the drive assembly is said to be in its home position. To raise or lower the shade, the wand which is connected to the driven end of the universal joint is pulled downwardly. That bends the flexible shaft downwardly, moving the drive assembly to its drive position; and it causes the links and thus the knuckles of the universal joint to align. The user then rotates the wand and turns the universal joint and thus rotates the roller, to raise and lower the shade to the desired elevation. When the desired setting is reached, the user lightly raises the wand upwardly, and then releases the wand. The universal joint will then be in the home position again, with knuckles at nominally right angles. Thus, the weight of the wand (and handle) hinders counter-rotation and unwinding of the shade from the roller. Unwinding is also prevented by contact of the wand with the wall or frame of the opening, or by contact with the fabric of the shade, according to the direction of the unrolling moment and the particular application. 
     In an embodiment of the invention the universal joint is comprised of specially configured mating knuckles. Preferably at least the driven knuckle has a U shape link with a slot which closely fits the head of the link of the mating knuckle; and, there is a wider portion of the slot near the inner end of the link, sufficient to enable rotation of one link within the slot of the other. The unique knuckles have particularly smooth driving action compared to a common universal joint and are particularly positive with respect to locking the roller in the desired position. 
     The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of preferred embodiments and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a shade on a roller with a driver mechanism comprised of a wand and joint in the drive position. The components are also shown in their home or lock position, in phantom. 
         FIG. 1A  is a partial perspective view of the lower end of a wand having both a collar and an articulating crank end. 
         FIG. 2  is a perspective is a perspective view of the portions of the apparatus shown in  FIG. 1 , when in the home or lock position. 
         FIG. 3  is a side view of a U shape link of a knuckle, with the knuckle body in phantom. 
         FIG. 4  is a side view of an alternative U shape link. 
         FIG. 5  is a side view showing how a drive knuckle moves from the rest or lock position to the drive position, relative to a driven knuckle, in a knuckle joint. 
         FIG. 6A  shows two joint knuckles assembled in their drive position, with the driven knuckle  36  in side view. 
         FIG. 6B  shows the assembly of joint knuckles from  FIG. 6A , with the driven knuckle  36  in top view. 
         FIG. 7  is similar to  FIG. 6B , and shows a knuckle joint in its drive position, corresponding in pictured orientation with  FIG. 1 . 
         FIGS. 8A ,  8 B, and  8 C are respectively side, edge, and end views of a U shape link of a knuckle. 
         FIG. 9  is a quasi-isometric view of the body of a knuckle attached to the end of a wand, with the top part of the U shape link cut away.  FIG. 9  is particularly related to  FIG. 3 . 
         FIG. 10  is a vertical cross section through the link of knuckle  36  as shown in the assembly of  FIG. 6B . 
     
    
    
     DESCRIPTION 
     The disclosure of provisional U.S. patent application Ser. No. 61/357,252, filed Jun. 22, 2010, entitled “Cordless Roman Shade with Self-Locking Handle” and the disclosure of commonly owned U.S. patent application Ser. No. 12/829,834 of M. Hanley et al., filed Jul. 2, 2010, and entitled “Handle with Anti-Rotation Mechanism for a Window Treatment,” are hereby incorporated by reference. 
     Embodiments of the present invention relate to so-called cordless Roman shade window treatments, and means for raising and lowering such shades, which are described in the Ser. No. 12/829,834 application. The shades described in the application, and further below, may be used for other purposes than covering window openings, such as for other openings and spaces where it is desirable to adjustably control passage of light or matter. 
       FIG. 1  shows a window treatment assembly embodiment comprising a shade  26  and associated driver  29 , namely a wand  28  with handle  30 , for actuating and raising and lowering the shade. For simplicity in the following description, reference is often made to the wand as representative of the actuator which may comprise several parts, e.g., the handle, and articulated end, and a collar as described below. Shade  26  is shown partially rolled around roller  23 , the longitudinal axis of which is indicated by the line  24 . The ends of the roller  23  are rotatably supported in brackets  58  which attach to a window frame or the like, not shown, but suggested by frame phantom  59  at one bracket. In the generality of the invention, the shade assembly is attached to some supporting structure during use. 
     A driver assembly  20  for raising and lowering the shade comprises a driver  29 , a portion of which is wand  28 , universal joint  32  to the lower end of which is attached a wand  28 , and a flexible drive shaft  34  connecting roller  23  to the upper or near end of the universal joint, also referred to in particular as the knuckle joint. Flexible drive shaft  34  is preferably a tightly wound metal coil spring, an example of which is detailed below. Alternately, shaft  34  may be a piece of steel flexible shaft, well known in commerce. Shaft  34  may be connected to the end of the roller by various means, including that it may be force-fit or press-fit, pinned, or otherwise fastened within a cavity  25  at the end of the roller  23 . See  FIG. 2 . The other end of the shaft  34  is connected to universal joint  32 , in particular to the driven knuckle part  36 . Similar alternative means of attachment may be used to connect the shaft to the knuckle body. 
       FIG. 1  shows the elements in their operating or drive position, and indicates how counter-clockwise rotary motion (arrow A) imparted to the handle end  30  of wand  28  by a user results in the shade  26  being raised up and wound (arrow B) as a reel of fabric  22  about the roller  23 .  FIG. 1  shows that the wand has a handle  30  at its lower end, to make easier gripping of the wand by the user, and to add mass to the driver/wand for resisting counter-rotation as explained below. A wand may have no handle and may be a simple polygonal cross section plastic shaft. Alternately, the wand may have a crank end as described below and as shown in  FIG. 1A . 
     In  FIG. 1  the driver assembly  20  is shown in its operating or drive position, wherein the joint  32  is more or less straight, due to the user having pulled downwardly on the driver  29  and having overcome the resilient, or bias, force of the preferred flexible shaft  34 .  FIG. 1  also shows, in phantom, the drive assembly and elements when they are in their rest or home position. The items designated  20 P (assembly),  32 P joint),  34 P (shaft),  28 P (wand), etc., are the same items as those having the number with no suffix P. The assembly  20  moves from its operating position to its rest position (indicated by arrow C) when the user lightly thrusts the wand  28  upwardly, as described in more detail further below. When shaft  34  has the aforementioned coil spring construction, or a structural analog, the bias created by the resilience of the flexible shaft aids the upward motion. 
       FIG. 2  shows driver assembly  20  in more detail, in its rest position, where the parts of knuckle joint  32  are at a more or less right angle. Preferred joint  32  is comprised of two mating identical knuckle parts  36 ,  38 .  FIGS. 3 ,  8  and  9  detail the construction of typical knuckle part, or knuckle half,  38 ; and  FIG. 5-7  detail the construction and function of the knuckle joint. These aspects are discussed further below. 
     When, as shown in  FIG. 2 , wand  28  and knuckle joint  32  are in their home positions (also called the lock position), and counter rotation of the roller  23  is resisted. This can be understood as follows: If the roller  23  starts to rotate, that motion is transmitted through driven knuckle  36 . But knuckle  36  cannot rotate without also rotating with knuckle  38 , the centerline of which is at an about right angle to the centerline of knuckle  36  when the drive assembly is in its home position. The counter-rotation force transmitted to knuckle  38  is such as to tend to lift the wand  28 , to urge it to rotate toward a plane which is more of less perpendicular to the plane in which the shade and wand hang. (Alternately, when the shade winds around the roller in the opposite direction, counter-rotation will tend to push the wand into the plane of the window frame. Of course, the drive system may be moved to the opposite end of the roller from that shown in  FIG. 1  and the wand rotational directions will be reversed.) The term “counter rotation” is used here mostly in the sense of referring to unwanted motion which unwinds the sheet from the roller. 
     The weight of the wand, and the distance of its center of mass from the axis of rotation of the knuckle joint, create a moment which opposes the counter-rotation moment generated by the weight of the shade as it seeks to unroll off the roller. In the embodiment of  FIG. 1 , the center of gravity of the wand will depend on the weight of the wand and handle  30 . The distance between the center of gravity of the wand and the center of joint  32  will preferably be at least half the distance to the free end of the wand, i.e., half the distance to the outer end of handle  30 , in the embodiment of  FIG. 1  and  FIG. 2 . 
     When the system is in its rest position, and a user is not applying downward force to the wand, a preferred flexible shaft  34  has a stiffness and strength sufficient, to counter the weight of the wand and to cause the shaft  34  to approach a horizontal position, more or less in-line with, but still curving somewhat downward with respect to, the line of axis  24  of the roller. Another useful shaft  34  may have less stiffness or strength. 
     To raise or lower the shade, a user pulls downwardly on the wand  28 , overcoming any resilient resistance to deflection of shaft  34 . That causes the knuckle joint to move from the rest or lock position, shown in  FIG. 2  and in phantom in  FIG. 1 , to the drive position, shown in  FIG. 1 . 
       FIGS. 3 to 7  detail a preferred knuckle construction.  FIG. 5  shows how the wand-driven knuckle  38  rotates relative to the other knuckle  36  with which it is engaged. (For simplicity and consistency with the other related Figures,  FIG. 5  pictures the wand being rotated upwardly in the vertical plane, compared to the wand pulling the knuckle parts downwardly. The relative motion in Fig. is of course is the same relative motion which results when the wand and knuckle  38  are pulled downwardly.) 
     Both preferred embodiment knuckles have similar construction, which promotes economic production and assembly. (As indicated below they do not need to be identical in detail configuration.) With reference to  FIG. 3  to  FIG. 7 , typical knuckle  38  comprises a U shape link  40  which has a slot  48 . The slot has a wider portion  50  near the base or body  44  of the knuckle. When the wand is pulled downwardly, to bend the flexible shaft downward and thus to bring the links toward alignment, the wider portion of the slot enables the head  56  of drive knuckle  38  to rotate within the slot of the driven knuckle  36 , as illustrated by  FIG. 5 . 
     The U shape link  40  has a cross piece or head  56  that connects the opposing legs which define the slot  48 . Knuckle  36  is similarly configured, having a link  42 , slot  148  with wider portion  150 , and head  156 . As the knuckles move into lengthwise alignment due to the user pulling on the wand, the head  56  of the link  40  of knuckle  38  slides lengthwise within the slot  48  of link  42  of knuckle  36 . The resultant configuration is shown in  FIG. 6A  and  FIG. 6B  (which are respectively side and top views, and collectively referred to as  FIG. 6 ). When the knuckles are aligned lengthwise, rotating of the wand and attached drive knuckle  38  will rotate driven knuckle  36  and shaft  34 .  FIG. 7  is like  FIG. 6B ; it is another view of the knuckle joint  32  in its drive position, but pictured to correspond with  FIG. 1 . 
     When the user stops turning the wand upon reaching the desired extension of the shade, the user raises the wand upwardly in the lengthwise direction of the wand, which is the reverse of the motions just described and illustrated by  FIG. 5-6 . 
     Note that the rectangular, preferably square, cross section of head  56  of knuckle  38  fits closely in the slot  148  of the mating knuckle  36 . Thus, when moving from the drive to head position, the head  56  (and link  40 ) slides lengthwise in slot  148  of link  42  until it reaches the wider portion  150  at the base of the U shape link  42 . At that location, the knuckle  40  is able to rotate relative to knuckle  42  because the space  150  allows rotation of the head within the slot. See  FIG. 5 . The resilient force of the preferred flexible shaft  34 , and the continued light upward motion of the wand by the user, cause the knuckle  36  to resume its nominal horizontal position. The assembly will then reach the rest position (alternately called the home or lock position) shown in  FIG. 2 . The length dimensions of the different portions of the slot enable the aforementioned rotational motions. 
     The construction of a typical preferred knuckle is now described. Referring to  FIG. 3  and  FIG. 9 , the wand  28  is received in a hole  52  in the body  44  of the knuckle  38 . Link  40  is detailed in the three mutually orthogonal views of  FIGS. 8A ,  8 B and  8 C. Link  40  has legs with bulbous ends  52  which are gripped as they slide into the undercut of a transverse slot  54  of the body  44  when the assembly  20  is manufactured. Wand  28  is inserted into the cavity  52  next, so that the wand sticks upwardly in the space between the opposing side leg ends  52  of the link. That prevents the legs from moving laterally within the slot. Set screw  58  retains the wand in place. The other knuckle  36  is similarly constructed, except that it is the end of the flexible shaft  34  which keeps the bulbous leg ends of the link within the slot, instead of a wand. 
     In another embodiment of the invention, a link  42 A, shown in  FIG. 4 , has a slot  48 A which has a width W which is wider than the cross section of the head  56 A and a uniformly wide slot portion—i.e., portion  50  which characterizes link  42 , is absent and rotation of the head within the slot is possible along its whole length. Thus, the head  56 ,  56 A of one knuckle can rotate relative to the other knuckle at any point along the length of the slot, because the slot  48 A of a first knuckle is wide enough to enable rotation of the head  56 A of a second identical knuckle to turn within the slot  48 A. This embodiment has a less positive action since there is more “play” in the joint. 
     As will be appreciated, in the invention, both knuckles do not have to have identical construction, although making them so is an aid to economic mass production. In particular, the bases can have different configurations. And, a driven knuckle which has link defining a close head-fitting slot with wider portion (as shown in  FIG. 3 ) may be used with a drive knuckle which has a plain, wide slot (as shown in  FIG. 4 ). 
     The knuckle and universal joint construction described above is a special (and unique) case of a universal joint. A common universal joint, known in commerce, or a knuckle joint without the special fit of the preferred embodiment described above, may be used in carrying out the invention. As will be appreciated from the foregoing, a knuckle joint is one in which the mating parts which are engaged are loop shaped, preferably U-shape. Common universal joints and flexible shafts are commercially available from McMaster Carr, Inc., Robinsville, N.J.; although for common commercial window treatments lower cost and thus more primitive items may be preferred. The ease of operation and range of functionality may be less good when the embodiment comprises a commercial universal joint of a common knuckle joint. Even so, there will not be significant counter-rotation, by which is meant that the sheet will not unwind from the roller in a degree which is substantial compared to the mean useful extension of the sheet from the roller. 
     The reason for preference of the special configuration knuckle joint which is described in connection with  FIG. 3-7  is as follows. Reference should be made to  FIG. 10 , which is a cross section through the knuckle assembly of  FIG. 6B . When the parts of the knuckle joint are in a working or drive position, where the parts of the joint lie in some approximation of straight line (which could be nominally along the z-axis), the knuckle joint of the present invention has one degree of substantial freedom of movement, e.g., in the x plane looking along said z-axis straight line. In comparison, a common universal joint under the same situation will have two degrees of freedom, i.e., in the x-plane and in the orthogonal y-plane. Given that the flexible shaft  34  is “wiggly” and resiliently “wants” to go to its home position, there is a tendency for a common low cost universal-type joint, especially, for example, one having mating links or loops, to “kick” out of alignment when being driven. That makes the use of the driver (wand) more erratic and uncertain from the standpoint of operator perception. The unique construction of the invention knuckles overcomes those problems in a surprisingly straightforward and economic fashion. 
     The wand is preferably a hexagonal or round rod of semi-rigid extruded acrylic plastic or polyvinylchloride plastic. The wand may have other cross sections, such as square. The wand may be a solid or hollow rod, and may be made of another plastic or metal. Other components of the drive system are preferably made of POM (polyoxymethylene) plastic. 
     From the foregoing it will be appreciated that there is a desirable interrelationship between the flexible shaft and the joint, whether it be a preferred knuckle joint or some other universal joint. 
     In another embodiment of the invention, the handle portion  30  of the wand  28  may be hinged relative to the rest of the wand length at one, preferably two, places, to thereby form a crank handle.  FIG. 1A  shows alternate embodiment wand  28 A which has a lower end  62  which is hinged at pivot pin  64 , so it can move as illustrated by the arrow to a position nominally perpendicular to the length axis  66  of the wand. Such an articulate wand is said to have a crank end.  FIG. 1A  also shows collar  60 , which may be a loosely-fit piece of semi-rigid or rigid plastic tubing within which wand  28 A freely rotates, is positioned around the lower end of wand  28 A. Thus, a user may grasp the collar and thereby steady the wand while applying the rotary force to the wand—in the instance of the crank end, by twirling the crank, often with a single finger. The collar may also be used on the wand in the embodiment of  FIG. 1 . In still another embodiment, the wand has a second hinged portion, so that the distal end of the wand may be made parallel to, but offset from, the wand portion which connects to the joint. See the related application Ser. No. 12/829,834. 
     While a simple wand, in its variations, is economic and effective, in the generality of the claimed invention the term wand and driver shall include other rotary drive means which are equivalent in function and result to a manually turned wand, for instance, an electric motor actuator connected to the universal joint directly, or by means of a wand or analogous structure. 
     The flexible shaft  34  is preferably a 2+ inch long tightly wound coil of 0.06 inch diameter music wire, i.e., hardened steel. It has an about one-quarter inch outside diameter. By “tightly wound” is meant that the adjacent turns of the coil are touching or nearly touching each other, i.e., the pitch of the turns of the coil is between 100 and 120 percent of the wire diameter. For reasons which are evident from the foregoing description, the shaft  34  is desirably resilient and sufficiently strong to help lift itself and the driven knuckle upwardly, when the user desires that to happen and pushes the wand upwardly. 
     In the generality of the invention, a flexible shaft need not have the resilience and “toward-horizontal” bias which has been described. In another embodiment of the invention, shaft  34  has insufficient resilience and or strength to overcome the weight of the wand, or none. When the shaft  34  has such character, the user may, after having changed the position of the shade by rotating the wand, raise the wand upwardly to thereby push the knuckle joint  32  upwardly, which will push the shaft  34  upwardly. That will cause the upper knuckle  36  to move to the horizontal home position, thereby enabling locking of the driver assembly. To the extent the shaft has such low strength that, upon release by the user, the weight of the wand will pull the shaft down to the point the knuckles become aligned, and the locking feature is defeated, the wand may be clipped to the frame of the window or a wall, as by a clip, magnetic means, etc. Alternately, when the handle is hinged to the rest of the wand length, as shown in  FIG. 1A , the handle may be bent nominally perpendicular to the wand length, to thereby form a crank end which can be placed in contact with a window frame or a fitting or the shade itself, to thereby resist counter-rotation of the wand. 
     The co-pending patent application Ser. No. 12/829,834, referred to above, describes a Roman shade with which the invention is particularly useful. Roman shades often are made of relatively heavy fabric. In the invention of the application Ser. No. 12/829,834 the Roman shade is raised by rolling up a lifting element, that is, a fabric piece which is attached to the lower end of the shade. The lifting element and not the shade itself is wound around the roller when it is rotated. See for example  FIG. 6  and  FIG. 9  of the related application. Thus, in the generality of the invention, rotation of the roller by the drive assembly can directly or indirectly lift the shade of a window treatment. 
     The invention, with explicit and implicit variations and advantages, has been described and illustrated with respect to one or more embodiments. Those embodiments should be considered illustrative and not restrictive. Any use of words such as “preferred” and variations suggest a feature or combination which is desirable but which is not necessarily mandatory. Thus embodiments lacking any such preferred feature or combination may be within the scope of the claims which follow. Persons skilled in the art may make various changes in form and detail without departing from the spirit and scope of the claimed invention.

Summary:
A window treatment, in which a shade is raised and lowered, is comprised of a roller upon which shade material is reeled and unreeled. A wand drives a universal joint, preferably a uniquely configured knuckle joint, and the universal joint drives a flexible shaft which is connected to the roller. Special shaping of the parts and slots of the U shape links of mating knuckles enables smooth and positive universal joint operation. A user may pull down on the wand, to bend the flexible shaft and bring the knuckles into alignment, whereupon turning of the wand rotates the roller. When the wand is released the resilience of the flexible shaft helps lift the driven knuckle so it is parallel to the horizontal roller, and the drive roller moves to a home position which inhibits counter-rotation of the roller due to the weight of the shade.