The system is applicable to any system having need for a positive stop at the end of a period of travel. In a vertical blind track system, a lead carrier which is typically manipulated by a control wand with universal linkage can include an installable and removable end stop engagement structure. This structure fits onto conventional lead carriers within a slot which is upwardly directed and at one side of the lead carrier. The installable and removable end stop engagement structure has a wide lateral slot, and including a first engagement member for engaging an edge of one end of the slot on the lead carrier, and a second engagement member which is angled and placed next to an extension to facilitate manual engagement and removal of the installable and removable end stop engagement structure. Once mounted in place, it aligns with, and is force or momentum inserted into and through a stop engagement aperture.

FIELD OF THE INVENTION 
   The present invention relates to the field of window coverings and more particularly for improvements in stabilizing any window covering which moves within a track, particularly at the terminus of its travel to achieve complete closure, with completion of closure transmitted to the user and which permits operation of the control and at the point of complete closure without inadvertently dislodging the window covering from its fully closed position. 
   BACKGROUND OF THE INVENTION 
   The conventional vertical blind system includes a single length elongate track having a series of either vertical blind vane carrier supports or a series of hanging supports. Further discussion will be had mostly about vertical blinds, for although the structures discussed herein can be utilized with a series of types of window coverings, the case where a control want is used to move the window covering across the window as well as to affect some other aspect of control, especially as by turning the wand to change the angle of vertical louvers, or other applied characteristics of the state of the window covering. 
   One arrangement which was employed to affect a positive close was set forth in U.S. Pat. No. 5,937,928 to the inventor of the instant invention and was entitled “MULTIPLE PULL ROD MULTIPLE VANE POSITIVE CLOSE CONTROL FOR A VERTICAL BLIND”, issued on Aug. 17, 2000, and is incorporated herein by reference. In this invention, a small magnet, typically having a cross or plus or (+) sectional shape was engaged into a lead carrier, especially where it was an end carrier, with the magnet engaging a metallic screw or rivet set located in a conventional end cap which was typically found at the end of a track supporting the carrier. 
   Factors affecting the performance of this arrangement includes the strength and positioning of the magnet, the compatibility of the metallic bolt with the end cap, as well as series of optional flat members which are used to support elongate structures within the track such as very long turning rods, etc. The system so disclosed not only provided some positive securing of the window cover, but provided up to three supporting flat members for cases where the track was long and where significantly long lengths of turning rod within the window covering and to prevent the sagging of and to support the turning rod. The use of the flat members also involved the use of an additional bolt in the carrier for engagement with a separate magnet in the flat member. As the flat members followed after the carrier, a series of placed screws in the head rail would engage upwardly projecting structures of the flat members and pick them away from the carrier one at a time to evenly distribute the flat members to support the turning rod. 
   The device thus outlined has the ability to perform closure at the center or ends of a window covering track. The employment of this structure required some alteration to the carrier, such as magnet insertion, bolt insertion for engaging the magnet of the flat member, often employing an additional flat member adjacent the end cap, and utilizing a two ended threaded rivet. 
   What is needed therefore is a system which can be more readily retrofitted onto existing carriers and window covering systems and which employs fewer parts. What is needed is a positive closure at the end of travel, coupled with an indication of such positive closure so that the user need not continue to try and insure that positive closure has occurred. In cases where the end of travel is against or adjacent a wall, non positive closure would cause the user to back the carrier up and again slide it with momentum against the end of the head rail. 
   Another concern is spacing adjacency from the end of the head rail. Where several flat members separate the end cap from the carrier, and especially where the carrier does not have some sort of carry around structure, a greater space is created between the carrier and the end cap which must be compensated for by a wall structure to shut out the light, or an extra covering louver behind which the carrier may be concealed. As such, a needed structure should allow the carrier to be fixed in as close a relation to the end cap as is possible, while giving the user a positive indication of fixation or lock, subject to the need for flat members to support an especially long internal turning rod. What is therefore also needed is a manner of forming positive closure in order that vertical blinds may be closed securely, exactly and precisely with regularity. The closure mechanism should be highly integratable with existing track systems and vertical blind carriers. The system may provide for a distributed system of support which will support any tendency of the rotation rod to sag. The system should provide positive feedback to the operator that the blinds are securely closed. 
   SUMMARY OF THE INVENTION 
   The improved system of the invention is applicable to any system having need for a positive stop at the end of a period of travel. In a vertical blind track system, a lead carrier which is typically manipulated by a control wand with universal linkage can include an installable and removable end stop engagement structure. The installable and removable end stop engagement structure fits onto conventional lead carriers within a slot which is upwardly directed and at one side of the lead carrier. The installable and removable end stop engagement structure has a wide lateral slot, and including a first engagement member for engaging an edge of one end of the slot on the lead carrier, and a second engagement member which is angled and placed next to an extension to facilitate manual engagement and removal of the installable and removable end stop engagement structure. Once mounted in place, and once an end cap for the head rail or sliding track is installed, the installable and removable end stop engagement structure has an expanded end which is force or momentum inserted into and through a stop engagement aperture. The expanded head has a split slot and the halves or other divided portions of the expanded head cantilever toward each other to enable the expanded head to clear the engagement aperture. 
   The system may be used with an optional flat support member  35  to help support a distributed control rod during the time that the lead carrier and single carriers are to one side. Multiple single carriers and multiple lead carriers may be utilized, especially at the ends of the head rail. The flat distributed position support member may follow the lead carrier by either magnetic force or by selective engagement with the installable and removable end stop engagement structure. 
   This system is further facilitated for use in existing structures by only having to by provide a locking member onto a conventional carrier, and providing an end cap having an aperture to permit friction and pressure locking of such locking member into the aperture. 
   The locking member has set offs which enable it to lock onto a carrier and achieve a constant spacing from the edge of the rail so as to align with an aperture provided in an end cap. The end cap typically has an oval depression, as is typical in the art, which provides a space for the tip end of the locking member to enter. The tip of the locking member has a split to allow two halves to cantilever toward each other. As the tip is momentum fed through the aperture by, the members on either side of the split move together so that the relatively larger diameter occupying areas of the member are guided through an associated aperture in the end cap and stop with a “snap” action. 
   The angle of the leading end of the tip as well as the angle aft of the maximum diameter occupying areas of the member defines the magnitude of momentum for both inertial insertion and force of disengagement. In the basic configuration, the invention may include simply an end cap with appropriate aperture, and the engagement member. The engagement member is provided as a single bullet shaped member having latch engagement members which over fit and engage the carrier. One or more side projections appropriately fit the spacing laterally with respect to the carrier to insure that the aperture in the end cap will be approached by the engagement member through its center. For both the left and right hand side approaches, the engagement member will be available in left and right side configurations. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a distributed exploded view of the ordering of components of a vertical blind track system, with track removed, and illustrating the interrelationship of the components; 
       FIG. 2  is a top view which illustrates the cooperation of the components seen in  FIG. 1 ; 
       FIG. 3  is a top view similar to that seen in FIG.  2  and illustrating the interfitting ability of the assembly on an opposite end, that a mirror configured stop is utilizable; 
       FIG. 4  is a side view which illustrates the action of the engaging stop before engagement; and 
       FIG. 5  is a side view as seen in FIG.  4  and illustrating full engagement of the stop into the end cap. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The description and operation of the invention will be best described with reference to  FIG. 1  which is a distributed exploded view of the ordering of components of a vertical blind track system  11 , with track removed, and illustrating the interrelationship of the components, including a lead carrier  15  having a control wand  17  connected into the lead carrier through a universal linkage  19 . The carrier has two pairs of wheels including a first pair of mutually adjacent wheels  21  and a second pair of mutually adjacent wheels  23 . The carrier  15  has a recessed cross shaped space  25  and an aperture or bore  27  for accepting an optional threaded member  29 . 
   An in-track turning distributed control rod  31  is shown in short section as extending through a turn actuation sleeve  33  supported within the lead carrier  15 . An optional flat support member  35  has a series of three upper projections  37 , 39 , &  41 , a rod accommodation bore  43 , and a stop accommodation bore  45 . In some cases, a magnet  47  is located within the flat support member  35  in order to engage with the threaded member  29  so that the flat support member  35  will travel along with the lead carrier  15  until one of the three upper projections  37 ,  39 , &  41 , engages a threaded member  51  shown suspended above the projection  41 . The threaded member  51  is usually engaged into the top of the head rail (not shown) the tail of the threaded member  51  protruding downwardly to interfere with the projection  41  as it translates along the head rail, to cause it to become separated from the lead carrier  11  and where it can provide added support to the turning distributed control rod  31  when the lead carrier is drawn back against a series of single carriers  55  leaving extended portions of the turning distributed control rod  31  otherwise unsupported. Note that flat support member  35  has a pair of notches  57  which engage internally disposed track structures (not shown) in the head rail which enable a much more exacting degree of support. In long head rail applications, where the lengths of the control rod  31  left un-supported with be great, several of the flat support members  35  may be used, each with its own associated one of the series of three upper projections  37 ,  39 , &  41  left standing in order to engage its associated threaded member  51 . 
   Adjacent the flat support member  35  is the end cap  61  having an upper aperture  62  which is amenable to engagement by a threaded member or locking pin or any other structure which facilitates holding the end cap  61  in the head rail (not shown in FIG.  1 ). End cap  61  has a recessed area  63 . Above the end cap  61  a threaded member  64  is seen and is of such length that combined with the thickness of the head rail and the distance between the top of the end cap  61  and the upper recessed area that the threaded member  64  will not penetrate the recessed area  63 . End cap  61  also has an aperture through which turning distributed control rod  35  extends (not seen in FIG.  1 ), and a stop engagement aperture  65 . The control rod  35  will be terminated in its extent within the recessed area, typically with a slide lock fitting, which helps hold the end cap onto the head rail (not shown). 
   To the other side of the lead carrier  15  and between lead carrier  15  and the single carrier  55  is shown a connector  67  which places the adjacent single carrier  55  in close relationship to the lead carrier  15 . The next most adjacent structures seen include a turning distributed control rod  31  shown adjacent a spacer  71  and an end cap  73  which may be a mirror image of the end cap  61 , and is shown with an aperture  75  through which turning distributed control rod  35  extends, and a stop engagement aperture  77 . There is no lead carrier adjacent the end cap  73  although there may be in an actual installation. The configuration of  FIG. 1  illustrates that the end caps  61 ,  73  are mirror images of each other unless their stop engagement apertures  77 ,  65  are the same size as their apertures, including aperture  75  through which turning distributed control rod  35  extends. If these apertures are the same size, a single configuration of end cap  61 ,  73  can be used. An end fitting  79  has a diameter greater than the aperture  75  and is for engaging the terminal end of the turning distributed control rod  31  and to better keep the end cap  73  in place with respect to the track (not seen in FIG.  1 ). 
   Above the lead carrier  15 , an installable and removable end stop engagement structure  81  is seen. The lead carrier  15  has an upper through slot  83  into which the end stop engagement structure  81  fits. The end stop engagement structure  81  has a generally cylindrically shaped body having a general centerline which over fits the base of the through slot  83 . At one end is a cylindrical extension  85  having an enlarged end  87  which is bifurcated by a slot  89  which allows the bifurcations to bend in a cantilevered fashion toward each other. Just past the enlarged end  87 , the cylindrical extension  85  has a conical section which may have an increased diameter to facilitate engagement with any structure provided to form a stop structure to the installable and removable end stop engagement structure  81 , especially where, for example a stop engagement aperture  65  has a matching diameter such that when the cylindrical extension  85  gets past the enlarged end  87 , the cylindrical extension  85  conical section may be stopped by a solid conical engagement with an appropriately sized engagement aperture  65 . This can permit several flat support members  35  to be engaged onto the cylindrical extension  85  which may easily clear the enlarged end  87  or not, as the case may be, but with a conic section just behind the enlarged end  87  which will stop the cylindrical extension  85  with regard to the engagement aperture  85 . 
   The main body of the end stop engagement structure  81  has a flat top  91  from which a pair of side spacing protrusions  93  extend in order to insure that the position of the end stop engagement structure  81  within the slot  83  will be at a position close to the center of the lead carrier in order to pre-align with the stop engagement apertures  77 ,  65  of the end caps  61 ,  73 . 
   The underside of the end stop engagement structure  81  includes a lateral slot  95  defined by a first projection  97  extending away from the cylindrical extension and for engaging the front corner of the base of the slot  83  recessed cross shaped space  25 , and a second more rounded and/or more gently angled projection  99  for engaging the rear edge of the base of the slot  83 . Projecting away from the end of the end stop engagement structure  81  opposite the cylindrical extension  85 , is a lip  101  to facilitate manual attachment and detachment of the end stop engagement structure  81  into and out of the slot  83 , especially facilitated by the combination of the size and shape of the second more rounded and/or more gently angled projection  99 . In typical fashion, the first projection  97  will be placed around the lower end edge of the slot  83 , and the second more rounded and/or more gently angled projection  99 , which can be more easily engaged over its lower end edge of the slot  83  being snapped into place with downward pressure on the flat top  91  perhaps combined with some upward pressure on the lip  101 . To remove the end stop engagement structure  81 , the reverse action of providing upward pressure on the lip  101  perhaps with some downward pressure on the flat top  91 . 
   The end stop engagement structure  81  could be made with a wider body, or the axis of its extent could be shifted, etc. However the side spacing protrusions enable the end stop engagement structure  81  to be advantageously located within the slot  83  to enable its engagement with the stop engagement apertures  65 ,  67 . 
   Referring to  FIG. 2 , a top view shows more of the thickness detail of the end cap  61  may have a boss  105  surrounding the stop engagement aperture  65  and which may advantageously give control of the ability to insure that the engagement aperture  65  has a well defined and precisely determinable inner diameter. A well defined internal diameter will enable reproducible control of the force necessary to move the enlarged end  87  of the cylindrical extension  85  through the stop engagement aperture  65 . 
   The flat support member  35  stop accommodation bore  45  is seen having the cylindrical extension  85  having passed through it. The interaction between the flat support member  35  stop accommodation bore  45  and the enlarged end  87  of the cylindrical extension  85  may range from complete non-interference to slight interference. Where the magnet  47  is not present, and a very slight interference, perhaps only a vertical interference, can be used to cause the flat support member  35  to follow the lead carrier  15  until separated by the threaded member  51 . With slight and controllable interference, and perhaps only in one dimension, on the way back, the flat support member  35  would either be re-engaged by the cylindrical extension  85  at a position near the threaded member  51  after the cylindrical extension has reached the boss  105 . Thus, the magnet  47  in combination with the threaded member  29  works well, but can, in some cases be eliminated. Recall also that the flat support member  35  is optional and only used where the extent of the control rod  31  is great such that it would be left to sag should the lead carrier  15  move the individual carriers  55  to one side. Where the flat support member  35  is not utilized, the shape of the cylindrical extension  85  may in any event be formed so that it will not overextend through the boss  105 . Put another way, the limitation of passage through the boss  105  may be dependent upon the size and shape of the cylindrical extension  85 . As can be seen in  FIG. 2 , the shape of the cylindrical extension  85  just past the enlarged end  87  is angled but of such size that the flat support member  35 , with its stop accommodation bore  45 , has passed over it. The diameter of the boss  105  may be so as to prevent further passage of the cylindrical extension  85 . In most applications, the end cap  61  may also be bound by a wall or other structure, and it too may act as an ultimate stop for the extent to which cylindrical extension  85  extends through the boss  105 , but preferably not. A break is shown in  FIG. 2  to illustrate that the system  11  may not necessarily consist of a single slide with one lead carrier  15 , but may consist of a system  11  having two lead carriers  15 , one at each end. 
     FIG. 3  helps to illustrate this. If the breaks in FIG.  2  and  FIG. 3  are considered to be such that the shorter ends are gone and what remains is part of complete system. A two lead carrier  15  system  11  results, but the other lead carrier  115  seen in  FIG. 3  is a mirror image of the lead carrier  15  of  FIGS. 1 & 2 . Aside from the mirror image carrier configuration of lead carrier  115 , the carrier itself may be such that it is reversible and is exactly the same as carrier  15 . However, even where this is so, the installable and removable end stop engagement structure  81  cannot be merely reversed as it would cause the pair of side spacing protrusions  93  to project toward the center of the carrier  115  and thus cause the centerline or center axis (running roughly through the slot  89  of the enlarged end  87  and through the gently angled projection  99 ) to move farther outboard of the carrier  115 . Thus carrier  115  utilizes a structure which is a mirror image to the installable and removable end stop engagement structure  81 , namely, a the installable and removable end stop engagement structure  121 . Aside from the mirror structure, other smaller aspects of the structures seen in  FIG. 3  are the same as structures of  FIGS. 1 & 2 . 
   Referring to  FIG. 5 , a side sectional view of a head rail  125  having a wheel track  127  illustrates the lead carrier with the the installable and removable end stop engagement structure  81  penetrating both the stop engagement aperture  65  of the end cap  61  as well as the stop accommodation bore  45  of the flat support member  35 . 
     FIG. 5  illustrates a view from the same perspective as that seen in  FIG. 4 , but with the the installable and removable end stop engagement structure  81  having been just disengaged from the stop engagement aperture  41 , but still carrying the flat support member  35  along with it. The operation is such that an operator urges lead carrier  15  toward the end cap  61  with enough force that the the installable and removable end stop engagement structure  81  cylindrical extension  85  enlarged end  87  extends through accommodation bore  65  and engages it to provide some force threshold which must be broken to remove the lead carrier  15  to travel in the other direction. While this positive end stop or temporary capture is in effect, the user can rotate the wand  17  to cause the vertical blind holders  135  to rotate without otherwise having to apply force to the lead carrier to hold the lead carrier in closed position. This translates to much less force which otherwise has to be applied to the wand  17 . The snap-stop action also lets the user know at what point the system  11  is completely closed to the full extent. In this way the user does not have to continually keep closing the vertical blind arrangement. When the user wants to open the vertical blinds by causing the carriers  55  to be collected at the other end, only enough initial pulling force need be applied to free the lead carrier  15 , and the relatively friction free wheels, such as wheels sets  21  and  23 , enable the user to very easily open and thereafter close the series of vertical blinds associated with the carrier. 
   While the present invention has been described in terms of a positive end stop system which can be utilized in both vertical blind and other window covering systems, both with and without a magnetic assist on a support member, one skilled in the art will realize that the structure and techniques of the present invention can be applied to many similar appliances. The present invention may be applied in any situation where positive end hold is desired, as well quick release operation. 
   Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.