Abstract:
An improved retractable covering for an architectural opening includes an improved mounting bracket, an improved limit stop to prevent over-retraction and over-extension of the retractable covering, an improved battery pack mounting bracket for attaching a power supply to a head rail of the retractable covering, an improved battery pack mounting apparatus for attaching a battery pack to a head rail, an improved control system for the retractable covering, and an improved method of using a wireless remote control or a manually operated switch to activate a motor to control the configuration of the covering, including the extension or retraction of the covering, and the transmissivity of the covering. The disclosed improvements are field retrofittable.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   The present application is a division of U.S. application Ser. No. 10/732,747, filed Dec. 10, 2003, which is a division of U.S. application Ser. No. 09/940,768, filed Aug. 27, 2001, now U.S. Pat. No. 6,688,368, which is a division of U.S. application Ser. No. 09/339,089, filed Jun. 22, 1999, now U.S. Pat. No. 6,299,115, issued on Oct. 9, 2001, which claims priority to U.S. provisional application No. 60/090,269, filed Jun. 22, 1998. Each of the above-referenced applications are hereby incorporated by reference as though fully set forth herein. 

   BACKGROUND OF THE INVENTION 
   a. Field of the Invention 
   The instant invention is directed toward a support structure and remotely controllable operating system for a retractable covering for an architectural opening. More specifically, it relates to the hardware for supporting a retractable covering for an architectural opening, and includes a control system that may be controlled manually or by use of a remote control transmitter. 
   b. Background Art 
   It is well known that it is frequently desirable to place retractable coverings for architectural openings in remote locations that are not easily accessible (e.g., coverings over windows that are substantially above ground level). In order to take advantage of the benefits inherent in such retractable coverings, it is necessary to be able to operate the coverings from a distance, and possibly without physically touching the actual hardware that retracts and extends the covering. 
   Although various attempts have been made to address the problems presented by such a remotely mounted covering, there remains a need for an improved apparatus for permitting remote operations of such remotely mounted retractable coverings for an architectural openings. 
   Prior attempts to control the retraction and extension of a covering using an electric motor have employed mechanical limit switches to stop the extension or retraction of the covering. It is, however, desirable to eliminate the presence of such mechanical limit switches. 
   SUMMARY OF THE INVENTION 
   It is an object of the disclosed invention to provide an improved retractable covering for an architectural opening. 
   It is a further object of the disclosed invention to improve the retractable covering with an improved mounting bracket. In one form of the mounting bracket, it has a top surface with at least one mounting slot through it, a back surface with at least one mounting slot through it, an upper leg, a lower leg, a lip slot defined between the upper leg and the lower leg, a pressure strip including a distal end and an opposite end, and a retention clip including a downward projecting portion. The retention clip is attached to the distal end of the pressure strip, and the opposite end of the pressure strip is mounted to the upper leg. In another form of the mounting bracket, the lower leg includes a split tongue having a compression slot across its width. In yet another form, the mounting bracket top surface has two adjustable mounting slots through it, and the back surface also has two adjustable mounting slots through it. 
   It is a further object of the disclosed invention to improve the retractable covering with an improved limit stop to prevent over-retraction and over-extension of the retractable covering. In one form of the limit stop, it has a mounting half and a working half that are pivotally attached to each other. The working half further includes a main body with an outer edge having at least one bottom rail stop arm projecting therefrom. The main body of the working half also includes an underside having at least one curvilinear portion extending therefrom and forming a pocket at it intersection with the main body of the working half. In a preferred form, the working half is pivotally attached to the mounting half by a hinge pin. If a hinge pin is used, the working half includes a main body having a hinge edge with a plurality of alternating hinge portions projecting therefrom, and the mounting half also includes a main body having a hinge edge with a plurality of alternating hinge portions projecting therefrom. The hinge portions from the working half cooperate with the hinge portions from the mounting half. It is yet a further object of the disclosed invention to improve the retractable covering with an improved battery pack mounting bracket for attaching a power supply to a head rail of the retractable covering. In one form of the battery pack mounting bracket, it includes a tongue having a base, and at least one upper leg attached to the base of the tongue so as to define a lip slot. This battery pack mounting bracket may be part of a battery pack mounting apparatus for attaching a battery pack to a head rail. The apparatus includes at least two battery pack mounting brackets and a distancing strip. The distancing strip establishes an appropriate distance between the two battery pack mounting brackets. In a preferred form, the distancing strip includes downward projecting lips that clip over the battery pack mounting brackets. Alternatively, the distancing strip may include one or more holes that server to position the distancing strip relative to the two battery pack mounting brackets. In another form, the battery pack mounting apparatus includes a first battery pack holding means to removably secure the battery pack to one of the battery pack mounting brackets, and a second battery pack holding means to removably secure the battery pack to the other of the battery pack mounting brackets. 
   It is a further object of the disclosed invention to improve the retractable covering with an improved control system that, if desired, may be operated at a location remote from the actual hardware attached to the retractable covering. In one form of the control system, it includes a means for mounting the retractable covering adjacent to an architectural opening, a power source, means for rotating an element on which the covering is rolled, means for commanding the means for rotating the element, means for preventing over-extension of the covering, and means for preventing over-retraction of the covering. 
   It is still a further object of the disclosed invention to improve the retractable covering with an improved method of using a wireless remote control or a manually operated switch to activate a motor to control the configuration of the covering, including the extension or retraction of the covering, and the transmissivity of the covering. If a wireless remote control, having an up button and a down button, is used, the method includes monitoring an amount of extension of the covering, monitoring an amount of transmissivity of the covering, monitoring a speed of the covering, and monitoring a signal from the remote control for an indication of a pressing of either the up button or the down button. Then, the method includes commanding the motor to make a predetermined adjustment to the covering upon recognizing a single press and release of either the up button or the down button, wherein the predetermined adjustment is based upon the monitored amount of extension, the monitored amount of transmissivity, the monitored speed, and the monitored signal. If a manual operating switch is used, the method includes monitoring an amount of extension of the covering, monitoring an amount of transmissivity of the covering, monitoring a speed of the covering, and monitoring a signal from the manual operating switch for an indication of a pressing of the manual operating switch. Then, the method includes commanding the motor to make a predetermined adjustment to the covering upon recognizing a single press and release of the manual operating switch, wherein the predetermined adjustment is based upon the monitored amount of extension, the monitored amount of transmissivity, the monitored speed, and the alternating treatment of the press of the manual operating switch as either an up request or a down request. 
   It is a further object of the disclosed invention that the remote control aspects of the control system be field retrofittable. 
   A more detailed explanation of the invention is provided in the following description and claims, and is illustrated in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary isometric view of the top and front of a retractable covering according to the present invention; 
       FIG. 1A  is an isometric view of a remote control comprising part of the present invention; 
       FIG. 2  is a fragmentary end view taken along line  2 - 2  of the apparatus depicted in  FIG. 1 ; 
       FIG. 3  is a fragmentary isometric view taken along line  3 - 3  of  FIG. 1 , depicting a section of the apparatus displayed in  FIG. 1 ; 
       FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3  through one of the main mounting brackets; 
       FIG. 5  is a fragmentary top view taken along line  5 - 5  of  FIG. 4 , depicting a portion of one of the main mounting brackets; 
       FIG. 6  is a partial cross-sectional view taken along line  6 - 6  of  FIG. 5 , depicting engagement of a main mounting bracket with the arcuate cover; 
       FIG. 7  is a partial cross-sectional view taken along line  7 - 7  of  FIG. 5 , depicting a locking tab engaging a pressure strip comprising a portion of a main mounting bracket; 
       FIG. 8  is an exploded isometric view of two components comprising part of a main mounting bracket; 
       FIG. 9A  is an exploded isometric view of a limit stop; 
       FIG. 9B  is an isometric view of the underside of the working half of the limit stop depicted in  FIG. 9A ; 
       FIG. 10  is a fragmentary cross-sectional view of the power supply taken along line  10 - 10  of  FIG. 2 ; 
       FIG. 11A  is an exploded fragmentary isometric view of the power supply depicted in  FIG. 10 ; 
       FIG. 11B  is a cross-sectional view of the head rail taken along line  11 B- 11 B of  FIG. 3  through the first battery pack mounting bracket; 
       FIG. 11C  is an exploded isometric view of the adjustable conductor-end anchor plate and the battery tube support piece shown in  FIGS. 10 and 11A ; 
       FIG. 11D  is an exploded isometric view of the compression spring slider piece and the compression spring anchor piece shown in  FIGS. 10 and 11A ; 
       FIG. 12  is a fragmentary cross-sectional view of the drive end (the right end as depicted in  FIG. 1 ) of the apparatus, showing placement of the gear motor; 
       FIG. 13  is a cross-sectional view taken along line  13 - 13  of  FIG. 12 ; 
       FIG. 14  is an exploded isometric view of the back side of the drive end taken along line  14 - 14  of  FIG. 1 ; 
       FIG. 15  is an exploded isometric view of the gears driven by the gear motor; 
       FIG. 16  is an exploded isometric view of the circuit board housing and components attached thereto; 
       FIG. 17  is an isometric view of the top side of the remote control; 
       FIG. 18  is an exploded isometric view of the back side of the remote control depicted in  FIG. 17 ; 
       FIG. 19  is a top planform view of the remote control depicted in  FIG. 17 ; 
       FIG. 20  is an end view of the remote control depicted in  FIG. 19  taken along line  20 - 20  of  FIG. 19 ; 
       FIG. 21  is a partial cross-sectional view taken along line  21 - 21  of  FIG. 3  through a limit stop and shows the limit stop capturing the stop rib when the retractable covering attempts to over extend; 
       FIG. 22  is a view similar to  FIG. 21  and shows the relative position of a limit stop with respect to the roll bar when the covering is in a normal, fully extended and fully open configuration; 
       FIG. 23  is a cross-sectional view of the head rail through a limit stop as the bottom rail is drawn upward toward the head rail as the covering approaches a fully retracted configuration; 
       FIG. 24  is a cross-sectional view of the head rail similar to  FIG. 23 , but wherein the covering is in its fully retracted configuration; 
       FIG. 25A  is a block diagram of the remotely-controllable operating system; 
       FIGS. 25B and 25C  are circuit diagrams of the electronics that control operation of the control system; and 
       FIGS. 26 ,  27 ,  28 ,  29 ,  30 ,  31 , and  32  together comprise a flow chart of the logic used by the control system of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In general, the instant invention relates to a remotely controllable retractable covering for architectural openings  10 . As depicted in  FIGS. 1 and 1A , the apparatus comprises a control system mounted in a head rail  12  for extending, retracting, and otherwise adjusting a covering  14  attached between the head rail  12  and a bottom rail  16 , wherein the control system mounted in the head rail may be operated using a remote control  18 . In a preferred embodiment, two main mounting brackets  20  attach the head rail  12  to a desired mounting surface (e.g., a wall above the opening), two battery pack mounting brackets  22  attach a power supply  24  to the head rail  12 , and two limit stops  26  prevent over-retraction and over-extension of the covering  14 . A particularly preferred covering  14  for use with the present invention comprises a first flexible sheet or element  28  and a second flexible sheet or element  30  with vanes  32  attached between these first and second flexible sheets  28 ,  30 , respectively. The first and second flexible sheets  28 ,  30 , respectively, are secured to the bottom rail  16 . Left and right end caps  34 ,  34 ′, respectively, support components, aesthetically shield various internal components from view, and include auxiliary support pockets  36  that may be used in select applications to position the head rail  12  above an architectural opening to be covered. As depicted in  FIG. 2 , the power supply  24  is hidden from view in the preferred embodiment when the head rail  12  is attached to a mounting surface. 
   Referring next to  FIGS. 3 ,  4 ,  5 ,  6 ,  7 , and  8 , details concerning the elements comprising each main mounting bracket  20  are described.  FIG. 3  depicts the main mounting bracket  20  supporting the right end of the apparatus as depicted in  FIG. 1 . As shown in  FIGS. 3 and 4 , each main mounting bracket  20  includes an upper break away tab  38  and a lower break away tab  40 . These upper and lower break away tabs  38 ,  40 , respectively, may be used to properly distance the head rail  12  from the mounting surface. If the tabs  38 ,  40  are not required, they may be broken away from the remainder of the main mounting brackets  20 . As shown to best advantage in  FIG. 3 , each main mounting bracket  20  comprises four adjustable mounting slots  42 , two on a top surface  43  and two on a back surface  45 . 
   Mounted in the center of each main mounting bracket  20  is a pressure strip  44 , which, in the preferred embodiment, is metallic. The pressure strip  44  is shown to best advantage in  FIGS. 5 and 8 . In  FIG. 8 , it is clearly shown that the pressure strip  44  includes a pair of holes including a locking tab hole  46  and a second hole  48 . Near a distal end  50  of the pressure strip  44 , a notch  52  is formed on each side of the pressure strip  44 , and the pressure strip  44  is slightly bent downward adjacent the notches  52  on the side of the notches  52  closest to the second hole  48 . 
     FIG. 8  also includes an isometric view of a retention clip  54 . The retention clip  54  comprises a downward projecting portion  56 , which snaps over the front of a top edge  58  of an arcuate cover  60  ( FIG. 1 ) when the mounting bracket  20  is positioned on the arcuate cover  60  (see  FIGS. 3 ,  4 , and  6 ). The retention clip  54  also includes a first upper guide  62 , a second upper guide  64 , and a lower guide  66 . When the retention clip  54  is slid onto the distal end  50  of the pressure strip  44 , the portion of the pressure strip  44  between its distal end  50  and the notches  52  is guided into the slot defined between the lower guide  66 , and the first and second upper guides  62 ,  64 , respectively, (see  FIGS. 5 and 6 ).  FIG. 5  shows the first and second upper guides  62 ,  64 , respectively, in position over the top surface of the section between the distal end  50  and the notches  52 .  FIG. 6  shows the same relationship between the first and second upper guides  62 ,  64 , respectively, and the section between the distal end  50  and the notches  52 ; and  FIG. 6  also depicts the lower guide  66  of the retention clip  54  riding on the bottom surface, as depicted, of the pressure strip  44  between its distal end  50  and the notches  52  in the pressure strip  44 . 
   As seen to best advantage in  FIGS. 5 and 8 , a pair of detents  68  are formed in the retention clip  54  beneath the first upper guide  62 . When the pressure strip  44  is inserted into the retention clip  54 , these detents  68  snap into the notches  52  in the pressure strip  44 . Once the retention clip  54  is thereby retained on the distal end  50  of the pressure strip  44 , the opposite end of the pressure strip  44  is inserted under a retention bridge  69  and into a slot  70  formed in the top surface  43  of the main mounting bracket  20 . This slot  70  in the top surface  43  of the main mounting bracket  20  may be seen to best advantage in  FIGS. 3 and 5 . When the pressure strip  44  is inserted completely into the slot  70  in the top surface  43 , a locking tab  72  snaps through the locking tab hole  46  in the pressure strip  44  (see  FIGS. 3 and 7 ), thereby retaining the pressure strip  44  in the slot  70  in the top surface  43  of the main mounting bracket  20 . 
   Once the main mounting bracket  20  is assembled by slipping the distal end  50  of the pressure strip  44  into the retention clip  54 , and then slipping the opposite end of the pressure strip  44  into the slot  70  in the top surface  43  of the main mounting bracket  20 , the main mounting bracket  20  may be attached to the head rail  12 . As may be seen to best advantage in  FIGS. 4 and 6 , the main mounting bracket  20  attaches to a mounting lip  74  of the arcuate cover  60 . Each main mounting bracket  20  includes an upper leg  76  and a lower leg  78  defining a slot  80  therebetween ( FIG. 6 ). As seen to best advantage in  FIG. 5 , both the upper leg and the lower leg (shown in phantom) extend laterally from side-to-side of the main mounting bracket  20 . When the main mounting bracket  20  is forced onto the arcuate cover  60 , it snaps into and retains its position thereon. In order to more clearly understand how each main mounting bracket  20  snappingly attaches to the arcuate cover  60 , several features of the arcuate cover  60  must first be described. 
   Referring to  FIGS. 4 ,  6 , and  21 , the elements of the arcuate cover  60  (labeled in  FIG. 1 ) are described. Each of these figures shows the cross section of the arcuate cover  60 . The arcuate cover  60  includes a top edge  58  that is substantially perpendicularly joined to a front surface  82  that is curved toward the covering  14  at the arcuate cover&#39;s  60  bottom edge  84 . Moving toward the rear of the head rail  12  (to the right in  FIGS. 4 ,  6 , and  21 ) from the intersection of the top edge  58  with the front surface  82  of the arcuate cover  60  along the bottom or inside portion of the top edge  58 , a downward ridge  86  is first encountered. Continuing toward the rear of the head rail  12 , the top edge  58  slopes downward at a shoulder  88  to the mounting lip  74 , which extends along the full longitudinal length of the back side of the top edge  58  of the arcuate covering  60 . The lowest point of the downward ridge  86  and the under side of the mounting lip  74  are substantially coplanar as seen to best advantage in  FIG. 6 . Moving downward, as depicted, along the front surface  82  of the arcuate cover  60  from the intersection of the front surface  82  with the top edge  58 , a support ledge  92  is encountered on the inside, as depicted, of the front surface  82 . Continuing substantially horizontally from the support ledge  92 , a support ridge  94  is next encountered. The support ledge  92  and the support ridge  94  are substantially coplanar. A sloped channel  96  is defined between the support ledge  92  and the support ridge  94 . An upper trough  98  is defined below the support ledge  92  between the back side of the front surface  82  and one side of the sloped channel  96 . Near the bottom edge  84  of the front surface  82  of the arcuate cover  60  a lower trough  100  is defined. The left and right end caps  34 ,  34 ′, respectively, each has an arcuate portion (not shown) defined on its inside surfaces that engages the upper and lower troughs  98 ,  100 , respectively, on the inside of the front surface  82  of the arcuate cover  60 . Thus, the end caps  34 ,  34 ′ are frictionally held onto the arcuate cover  60  by the upper and lower troughs  98 ,  100 , respectively. 
   Referring again to  FIGS. 4 and 6 , attachment of the main mounting brackets  20  to the arcuate cover  60  is now described. The lower leg  78  of each main mounting bracket  20  includes a split tongue  102  having a compression slot  104  across its entire width. In other words, the compression slot  104  shown in cross section in  FIGS. 4 and 6  extends through the lower leg  78  from one lateral edge of the lower leg  78  to the other lateral edge. When the mounting bracket  20  is forced onto the arcuate cover  60 , the split tongue  102  portion of the lower leg  78  is inserted into the “pocket” formed by the underside of the mounting lip  74 , the downward ridge  86 , the support ledge  92 , and the support ridge  94 . Since the top-to-bottom thickness of the split tongue  102  of the lower leg  78  is slightly greater than the vertical distance between the plane defined by the downward ridge  86  and the inside of the mounting lip  74 , and the plane defined by the support ledge  92  and the support ridge  94 , the split tongue  102  is compressed slightly as it is inserted into the previously defined pocket. The compression slot  104  thereby decreases in size as the split tongue  102  is forced into the pocket. Since the upper and lower portions of the split tongue  102  resist this compression, this resistance helps maintain the main mounting bracket  20  in position. 
   While the split tongue  102  is being inserted into the above-defined pocket, the slot  80  defined between the upper leg  76  and the lower leg  78  of the main mounting bracket  20  slides over the mounting lip  74  on the top edge  58  (see  FIG. 6 ). When the mounting lip  90  is completely seated into the slot  80 , the downward projecting portion  56  of the retention clip  54  snaps over the corner of the top edge  58 . The main mounting bracket  20  is thus held securely in position by the split tongue  102 , slot  80 , and retention clip  54 . In particular, the main mounting bracket  20  cannot move further leftward in  FIG. 6  because the base of the mounting lip  74  is pressing against the bottom of the slot  80 , and the main mounting bracket  20  will not move rightward in  FIG. 6  because of the downward projecting portion  56  of the retention clip  54 . Similarly, up-and-down motion of the main mounting bracket  20  is inhibited by the interaction between the lower leg  78 , the upper leg  76 , the retention clip  54 , and the arcuate cover  60 . If it becomes desirable to remove the main mounting bracket  20  from the arcuate cover  60 , the downward bias generated by the pressure strip  44  that keeps the retention clip  54  clipped over the arcuate cover  60  may be overcome by lifting upward on the retention clip  54 , for example, by pressing a thumb upward against the downward projecting portion  56  of the retention clip  54  to force it onto the top edge  58  of the arcuate cover  60 . When the downward projecting portion  56  of the retention clip  54  is thus disengaged from the arcuate cover  60 , the main mounting bracket  20  may be pulled rightward in  FIGS. 4 and 6  with sufficient force to completely remove the main mounting bracket  20  from the arcuate cover  60 . 
   Referring next to  FIGS. 1 ,  3 ,  9 A,  9 B,  21 ,  22 ,  23 , and  24 , construction of a limit stop  26  and attachment of the limit stop  26  to the arcuate cover  60  is described next. As clearly depicted in the preferred embodiment of  FIGS. 1 and 3 , the present invention includes two limit stops  26  that prevent over-retraction and over-extension of the covering  14 .  FIG. 9A  is an exploded, isometric view of one limit stop  26 . As shown in this figure, each limit stop  26  comprises four main components: a mounting half  106 , a working half  108 , a biasing spring  110 , and a hinge pin  112 . 
   Looking first at the working half  108 , one edge comprises a plurality of alternating hinge portions  114 . In the preferred embodiment, these hinge portions  114  each comprise approximately half of a hinge section. Corresponding hinge portions  116  are located on the mounting half  106 . The hinge portions  114  on the working half  108  interlock with the hinge portions  116  on the mounting half  106 , thereby forming a hinge channel to accommodate the hinge pin  112 . When the mounting half  106  and the working half  108  of the limit stop  26  are assembled, the hinge pin  112  is slid through the channel defined by the hinge portions  114 ,  116 , and the hinge pin  112  is slid through a loop in the central portion of the biasing spring  110  to maintain the spring&#39;s position between the mounting half  106  and the working half  108 . A spring groove  118  is cut in the top portion, as depicted, of the main body  113  of the working half  108 , and a similar spring groove (not shown) may be formed in the middle one of the retention fingers  122  on the mounting half  106 . Two pivot stops  124  are mounted on the working half  108  of the limit stop  26 . These pivot stops  124  comprise plate-like surfaces near the hinge edge of the working half  108 . Two of the hinge portions  116  on the mounting half  106  comprise extensions  126  that impact the pivot stops  124  if the assembled limit stop  26  starts to flex too greatly in one direction about the hinge pin  112 . For example, in  FIGS. 9A and 21 , if the mounting half  106  were held stationary and the working half  108  were rotated far enough counter-clockwise, the extensions  126  on the mounting half  106  would impact the pivot stops  124  on the working half  108  of the limit stop  26 , thereby preventing excessive upward or counter-clockwise rotation of the working half  108  of the limit stop  26 . 
   Referring to  FIG. 9A , the mounting half  106  of the limit stop  26  includes three retention fingers  122  in the preferred embodiment. The retention fingers  122  are suspended above the main body  128 , thereby forming a “pocket” between the main body  128  and the retention fingers  122 . On a distal edge of the main body  128  is a substantially vertical projection  130 . 
   Referring now to  FIG. 21 , when the mounting half  106  of the limit stop  26  is slid onto the top edge  58  of the arcuate cover  60 , the substantially vertical projection  130  on the distal edge of the main body  128  snaps into an upper channel  132  (clearly visible in  FIGS. 4 and 6 ) defined by the front surface  82  of the arcuate cover  60  and the downward ridge  86  on the underside of the top edge  58  of the arcuate cover  60 , while the retention fingers  122  frictionally engage the top surface of the mounting lip  74  and the main body  128  slides under the mounting lip  74  and the downward ridge  86 . The limit stop  26  is thereby attached to the arcuate cover  60  in close frictional engagement therewith. 
   As shown in  FIGS. 9A ,  9 B, and  21 , the working half  108  of the limit stop  26  includes two bottom rail stop arms  134 . The function of the bottom rail stop arms  134  will be described further below with reference to  FIG. 24 . The underside of the working half  108  (see  FIG. 9B ) includes two curvilinear portions  136 , which ride on the outer surface of the covering  14  as it is rolled onto a roll bar  138  (see  FIG. 23 ). Where these curvilinear portions  136  intersect the main body  113 , a pocket  140  is defined (most clearly visible on the right-hand edge of  FIG. 9A ). As shown in  FIG. 21 , this pocket  140  helps prevent over-rotation of the roll bar  138  and over-extension of the covering  14 . If, for some reason, the apparatus attempts to over extend the covering  14 , a forward extending stop rib  142  of the roll bar  138  gets trapped in the pocket  140  defined behind the curvilinear portions  136  ( FIG. 21 ). When the forward extending stop rib  142  is thus captured by the pocket  140 , a motor  144  ( FIG. 12 ) rotating the roll bar  138  is stalled, preventing over-rotation of the roll bar  138 . From the direction depicted in  FIG. 21 , the roll bar  138  rotates clockwise during extension of the covering  14  and counter-clockwise during retraction of the covering  14 . 
   Starting from the position shown in  FIG. 21 , when it is time to retract the covering  14 , the roll bar  138  is caused to rotate counter-clockwise by the gear motor  144  (the gear motor is clearly visible in  FIG. 12 , for example). The curvilinear portions  136  of the working half  108  of the limit stop  26  are designed to permit retraction of the covering  14  even after the apparatus has attempted to overly extend the covering  14 . The shape of the forwarding extending stop rib  142  also helps in this regard since it has an arched back surface that impacts the curvilinear portions  136  during retraction of the covering  14  (i.e., during the first counterclockwise rotation of the roll bar  138  as depicted in  FIG. 21 ). 
   Referring now to  FIGS. 1 ,  3 ,  11 A,  11 B,  11 C, and  11 D, attachment of the power supply  24  to the head rail  12  is described next. Referring first to  FIGS. 3 ,  11 A, and  11 B, the portions of each battery pack mounting bracket  22  that mounts it to the arcuate cover  60  are described next. First and second upper legs  146 ,  148 , respectively, extend over a substantially longer tongue  150  having a substantially rectangular port or window  152  in it ( FIG. 11A ). A pair of slots  154  are formed where the first and second upper legs  146 ,  148 , respectively, intersect the base of the tongue  150  ( FIG. 11A ). A flexible arm  156  ( FIG. 11B ) extends from the side of the port  152  nearest the base of the tongue  150  and substantially fills the port  152 . Near the free end of the flexible arm  156 , a pair of ridges  158 ,  160  on the underside of the flexible arm  156  define a channel  162 . When the battery mounting bracket  22  is in position on the arcuate cover  60 , the tip  151  (see  FIG. 11A ) of the tongue  150  extends into the “pocket” defined by the downward ridge  86 , the underside of the mounting lip  74 , the support ledge  92 , and the support ridge  94  (the support ledge  92  and the support ridge  94  are clearly shown in  FIG. 6 ). The two slots  154  between the first and second upper legs  146 ,  148 , respectively, and the tongue  150  frictionally engage the mounting lip  74 , and the channel  162  in the flexible arm  156  captures the support ridge  94 , with the second ridge  160  of the flexible arm  156  being accommodated by the sloped channel  96  integrally formed in the arcuate cover  60  ( FIG. 11B ). 
   Referring next to  FIGS. 1 ,  2 ,  10 ,  11 A,  11 C, and  11 D, the power supply  24  and hardware for mounting it to the head rail  12  are next described. As shown to best advantage in  FIGS. 1 and 2 , the power supply  24  is mounted on the back side of the head rail  12  and is thereby substantially hidden from view.  FIG. 11A  is an exploded view of the components comprising the power supply  24 . The battery pack mounting brackets  22  are attached to the arcuate cover  60  as previously described. The appropriate distance, which is a function of the length of the battery tube (or battery pack)  206  which itself is a function of the energy requirements of the control system, is established between the mounting brackets  22  using a distancing strip  164  (see  FIGS. 10 and 11A ). As shown in  FIGS. 10 and 11A , the distancing strip  164  has a lip  166  on each end of it and a hole  168  near each end of it. The lip  166  on one end of the distancing strip  164  clips over one mounting bracket  22 , while the lip  166  on the opposite end of the distancing strip  164  clips over the edge of the other battery pack mounting bracket  22 . The distancing strip  164  in position with the lips  166  so arranged with respect to the battery pack mounting brackets  22  is most clearly shown in  FIG. 10 . A strip bed  170  ( FIG. 11A ) is defined in the bottom of each battery pack mounting bracket  22 , and a placement pin  172  projects from the bottom of the strip bed  170 . The strip bed  170  is approximately as deep as the distancing strip  164  is thick. Thereby, when the distancing strip  164  is properly placed, the placement pin  172  in each battery pack mounting bracket  22  is accommodated by the holes  168  in the distancing strip  164 , and the strip bed  170  in each battery pack mounting bracket  22  is substantially filled by the distancing strip  164 . 
   Once the first and second battery pack mounting brackets  22  are attached to the arcuate cover  60 , and are arranged the appropriate distance apart by the distancing strip  164 , the remainder of the power supply  24  may be assembled. A first conductor terminal plate  174  is attached to a conductor plate bed  176  in an adjustable, conductor-end anchor piece  178  ( FIGS. 11A and 11C ). The first conductor terminal plate  174  is metal, while the adjustable, conductor-end anchor piece  178  is plastic in the preferred embodiment. The first conductor terminal plate  174  may be snapped onto pins extending from the conductor plate bed  176 , or it may be bolted onto the conductor plate bed  176 , or the first conductor terminal plate  174  may be glued directly onto the conductor plate bed  176 . Subsequently, a battery tube support piece  180  is attached to the adjustable, conductor-end anchor piece  178  (best seen in  FIG. 11C ). In the preferred embodiment, the battery tube support piece  180  snaps onto the adjustable, conductor-end anchor piece  178 . The battery tube support piece  180  includes a conductor port  182  ( FIG. 11A ). A second conductor terminal plate  184  is riveted to the battery tube support piece  180  in the preferred embodiment (see  FIG. 11C ). 
   Once the adjustable, conductor-end anchor piece  178  and the battery tube support piece  180  are fixed to one another in the manner described further below, a first locking lug  186  is attached to the adjustable, conductor-end anchor piece  178 . The locking lug  186  is inserted into a lug hole  188  in the adjustable, conductor-end anchor piece  178 . The first locking lug  186  includes a screwdriver slot  190  in a cylindrical portion  192 , and an irregular, enlarged portion  194  is adjacent the cylindrical portion  192 . The lug hole  188  includes an expansion slot  196  through the center of it. When the first locking lug  186  is rotated using a screwdriver inserted into the screwdriver slot  190 , the enlarged portion  194  of the first locking lug  186  tends to expand the expansion slot  196 , thereby preventing the adjustable, conductor-end anchor piece  178  from sliding in the first battery pack mounting bracket  22 . The adjustable, conductor-end anchor piece  178  includes a first lip  198  and a second lip  200  near its bottom surface ( FIG. 11C ). Once the first locking lug  186  is inserted into the lug hole  188  in the adjustable, conductor-end anchor piece  178 , and after the first conductor terminal plate  174  has been attached to the adjustable, conductor-end anchor piece  178 , and the battery tube support piece  180  has been attached to the adjustable, conductor-end anchor piece  178 , the first lip  198  may be slid into a first groove  202  of the first battery pack mounting bracket  22 , while the second lip  200  is slid into a second groove  204  of the first battery pack mounting bracket  22 . When the adjustable, conductor-end anchor piece  178  is thus slid into the first battery pack mounting bracket  22 , the anchor piece  178  rides on top of the distancing strip  164 , thereby keeping the distancing strip  164  in its strip bed  170 , and keeping the first locking lug  186  in the lug hole  188  in the anchor piece  178 . Once the anchor piece  178  is positioned at a desired location, the first locking lug  186  may be rotated to expand the expansion slot  196  and thereby nonpermanently fix the anchor piece  178  to the first battery pack mounting bracket  22 . 
   The power supply  24  on the preferred embodiment also includes a side-by-side battery tube  206 , which, in the preferred embodiment, holds eight AAA batteries  208 . One end of the battery tube  206  includes a fixed end cap  210  having two external conductor strips on it. The second external conductor  212  is visible in  FIG. 11A . The opposite end of the battery tube includes a removable end cap  214  having a conductive strip  216  on its inner surface to connect the four batteries  208  in one side of the battery tube  206  in series with the four batteries  208  on the opposite side of the battery tube  206 . The removable end cap  214  also includes a figure eight portion  218 , which fits into an end of the side-by-side battery tube  206  until the conductive strip  216  contacts the batteries  208  in the battery tube  206 . The removable end cap  214  also includes a cylindrical portion  220  that is cradled by a compression spring slider piece  222  (see  FIG. 11D ). When the fixed end cap  210  of the battery tube  206  is properly inserted into the battery tube support piece  180 , the external conductors on the fixed end cap  210  make electrical contact with the first and second conductor terminal plates  174 ,  184 , respectively (both may be seen in  FIG. 11C ). In particular, the second external conductor  212  on the fixed end cap  210  makes electrical contact with the second conductor terminal plate  184 , which is riveted to the conductor port  182  in the battery tube support piece  180 . Similarly, the first external conductor on the fixed end cap  210  makes electrical connection with the first conductor terminal plate  174  mounted in the conductor plate bed  176  of the adjustable, conductor-end anchor plate  178 . As shown in  FIG. 11C , a first wire lead  224  is soldered to the first conductor terminal plate  174 , and a second wire lead  222  is soldered to the second conductor terminal plate  184 . 
   The cylindrical portion  220  of the removable end cap  214  is supported by the compression spring slider piece  222  ( FIGS. 10 and 11D ). The compression spring slider piece  222  includes an arcuate support surface  228  that cradles the cylindrical portion  220  of the removable end cap  214 . An arcuate outer wall  230  also engages the cylindrical portion  220  of the removable end cap  214 . An abutment surface  232  extends between the arcuate support surface  228  and the arcuate outer wall  230 , and this abutment surface  232  presses against the end of the removable end cap  214 , holding it in position. 
   One side of the compression spring slider piece  222  includes a range-limiting bracket  234 . The range-limiting bracket  234  extends around and behind an upright wall  236  of a compression spring anchor piece  238 . A compression spring  240  maintains pressure between the compression spring anchor piece  238  and the compression spring slider piece  222 . The compression spring slider piece  222  and the compression spring anchor piece  238  each includes a spring-mounting pin  242  having an outside diameter that is substantially the same size as the inside diameter of the compression spring  240 . The compression spring  240  may be thereby slid onto the spring-mounting pins  242 . 
   To assemble the three primary components that support the removable end cap  214 , a second locking lug  244  (which is the same as the first locking lug  186  in the preferred embodiment) is inserted into a lug hole  246  in the compression spring anchor piece  238 . This lug hole  246  (visible in  FIGS. 11A and 11D ) similarly is divided by an expansion slot  248  in the base of the compression spring anchor piece  238 . The compression spring anchor piece  238  includes a first lip  250  and a second lip  252 . The first lip  250  is slidably engaged in a first groove  254  of the second battery pack mounting bracket  22 , while the second lip  252  of the compression spring anchor piece  238  is slidable engaged in a second groove  256  of the second battery pack mounting bracket  22 . Since the first and second battery pack mounting brackets  22  are the same in the preferred embodiment, the first groove  254  of the second battery pack mounting bracket is the same as the first groove  202  of the first battery pack mounting bracket. Similarly, the second groove  256  of the second battery pack mounting bracket is the same as the second groove  204  of the first battery pack mounting bracket. When the anchor piece  238  is thus slid into the second battery pack mounting bracket  22 , the underside (not labeled) of the anchor piece  238  keeps the distancing strip  164  in the strip bed  170  of the second battery pack mounting bracket  22 , and the second locking lug  244  is held in the lug hole  246 . The compression spring slider piece  222  also includes a first lip  258  and a second lip  260 . The compression spring  240  is slid over the mounting pin  242  of the anchor piece  238 , and then the first and second lips  258 ,  260 , respectively, of the compression spring slider piece  222  are slid into the first and second grooves  254 ,  256 , respectively, of the second battery pack mounting bracket  22 , while ensuring that the range-limiting bracket  234  is placed around the upright wall  236  of the compression spring anchor piece  238 . Once the anchor piece  238  and the slider piece  222  are each inserted into the grooves  254 ,  256  of the second battery pack mounting bracket  22 , and the compression spring  240  is properly placed between these two pieces  238 ,  222 , they may be placed in a desired position along the first and second grooves  254 ,  256 , respectively. Once the anchor piece  238  is properly positioned, a screwdriver blade is inserted into the screwdriver slot of the second locking lug  244 , and the second locking lug  244  is rotated to spread the expansion slot  248  and thereby hold the compression spring anchor piece  238  in the desired position in the first groove  254  and second groove  256  of the second battery pack mounting bracket  22 . The compression spring anchor piece  238  thereby also keeps the compression spring slider piece  222  from falling out of the first groove  254  and second groove  256  of the second battery pack mounting bracket  22 . 
   If the slider piece  222  slides in a first direction, it eventually compresses the compression spring  240  enough that the slider piece  222  cannot slide any further in the first direction. If, on the other hand, the slider piece  222  slides in the opposite direction, the range-limiting bracket  234  eventually gets caught by the upright wall  236  of the compression spring anchor piece  238 . When the removable end cap  214  is properly mounted to the end of the battery tube  206 , it may be slid into the compression spring slider piece  222 . In order to insert the battery tube  206  into position, it may be necessary to manually force the slider piece  222  toward the anchor piece  238 , thereby compressing the compression spring  240  to provide sufficient space to slip the cylindrical portion  220  of the removable end cap  214  into frictional engagement with the arcuate support surface  228  and the arcuate outer wall  230  of the compression spring slider piece  222 . When the compression spring  240  is permitted to force the compression spring slider piece  222  away from the compression spring anchor piece  238 , the pressure generated by the spring  240  maintains the battery tube  206  in the desired position between the battery tube support piece  180  and the compression spring slider piece  222 . 
     FIGS. 11C and 11D  show details concerning the hardware that support the ends of the battery tube  206  depicted in  FIG. 11A . Referring first to  FIG. 11C , details concerning the adjustable, conductor-end anchor plate  178  and the battery tube support piece  180  are described next.  FIG. 11C  shows details of the two pieces that support the fixed end cap  210  of the battery tube  206 , namely the adjustable, conductor-end anchor piece  178  and the battery tube support piece  180 . The conductor-end anchor piece  178  includes a conductor plate bed  176  integrally formed therein (see  FIG. 11A  for a clear view of the conductor plate bed  176 ). As shown in  FIG. 11C , the first conductor terminal plate  174  is mounted in the conductor plate bed  176 , and a first wire lead  224  is soldered to the first conductor terminal plate  174 . Near the mid section of the conductor end anchor piece  178  are two upright support arms  262 , each having a hole in its distal end (see  FIG. 11C ). These substantially vertical upright support arms  262  flex outward slightly so that the holes in the support arms  262  will snap over the mounting pins  264  on the battery tube support piece  180  when the battery tube support piece  180  is snapped into position. 
   On the left end of the conductor-end anchor piece  178 , as depicted in  FIG. 11C , is a lug hole  188  and expansion slot  186 , which are both integrally formed in the conductor-end anchor piece  178 . The lug hole  188  rotatably accommodates the cylindrical portion  192  of the first locking lug  186 . The bottom side (not shown) of the conductor-end anchor piece  178 , below the lug hole  188  shown in  FIG. 11C , is cut out to accommodate the enlarged portion  194  of the first locking lug  186 . The cylindrical portion  192  has a screwdriver slot  190  formed therein. When the first locking lug  186  is positioned in the lug hole  188  and a screwdriver is used to rotate the locking lug  186 , the enlarged portion  194  of the locking lug  186  expands the expansion slot  196  in a known manner to force the first lip  198  and second lip  200  apart. Thus, when the first lip  198  of the conductor-end anchor piece  178  is in the first groove  202  of the first battery pack mounting bracket  22  and the second lip  200  is in the second groove  204  of the first battery pack mounting bracket  22 , rotation of the locking lug  186  nonpermanently fixes the position of the conductor-end anchor plate  178  relative to the first battery pack mounting bracket  22 . 
   The battery tube support piece  180  includes a pair of mounting pins  264  that are pivotally accommodated by the substantially vertical upright support arms  262  of the conductor-end anchor piece  178 . The mounting pins  264  are positioned below the conductor port  182  (visible in  FIG. 11A ) of the battery tube support piece  180 . The mounting pins  264 , which define the pivot axis of the battery tube support piece  180  are also mounted below the center of the abutment surface  266  of the support piece  180  (the center of the abutment surface  266  roughly corresponds to the position of the conductor port  182 , which has the second conductor terminal plate  184  riveted to it in  FIG. 11C ). Thus, when the fixed end cap  210  of the battery tube  206  is positioned against the abutment surface  26  of the battery tube support piece  180 , pressure exerted by the fixed end cap  210  against the abutment surface  266  tends to rotate the battery tube support piece  180 , if at all, counterclockwise about the mounting pins  264  depicted in  FIG. 11C . This counterclockwise rotation of the battery tube support piece  180  in the holes in the upright support arms  262  of the conductor-end anchor piece  178  rotates the trailing edge  268  of the support piece  180  against the surface of the conductor-end anchor piece  178 . 
   As clearly shown in  FIG. 11C , the second conductor terminal plate  184  is riveted in the conductor port  182  (visible in  FIG. 11A ), and the second wire lead  226  is soldered to the second conductor terminal plate  184 , which is visible in  FIG. 11C . When the battery tube  206  is correctly positioned in the battery tube support piece  180 , and the battery tube support piece  180  is snapped into position in the conductor-end anchor piece  178 , the batteries  208  in the battery tube  206  are connected in series with the first wire lead  224  and the second wire lead  226 . The first and second lead wires  224 ,  226 , respectively, are then connected to a plug  270 , which may be seen in  FIG. 3 . Once the power supply  24  is positioned on the back of the head rail  12 , the plug  270  on the end of the first wire lead  224  and the second wire lead  226  is plugged into a power connection port  272  visible in, for example,  FIGS. 3 and 14 . 
   Focusing now on  FIG. 11D , the details concerning the hardware components that support the removable end cap  214  of the battery tube  206  are described next. The compression spring anchor piece  238  includes a lug hole  246  divided by an expansion slot  248 . The lateral edges of the bottom portion of the anchor piece  238  comprises a first lip  250  and a second lip  252 . When the anchor piece  238  is correctly positioned in the second battery pack mounting bracket  22  ( FIG. 11A ), the first lip  250  rides in the first groove  254  and the second lip  252  rides in the second groove  256 . Once the anchor piece  238  is correctly positioned in the second battery pack mounting bracket  22 , the locking lug  244  is rotated in the lug hole  246  to expand the expansion slot  248  and frictionally bind the anchor piece  238  in the second battery pack mounting bracket  22 . The anchor piece  238  also includes a substantially vertical upright wall  236  that has a spring mounting pin  242  integrally formed thereon. Once the anchor piece  238  is properly positioned, the compression spring  240  may be slipped onto the spring mounting pin  242  of the anchor piece  238 . The spring mounting pin  242  is designed to frictionally fit into the inside of the compression spring  240 . The compression spring slider piece  222  is next positioned in the second battery pack mounting bracket  22  by placing the range-limiting bracket  234  around the upright wall  236  of the compression spring anchor piece  238  and slipping the first lip  258  and the second lip  260  on the bottom lateral edges of the slider piece  222  into the first groove  254  and second groove  256  on the second battery pack mounting bracket  22 . 
   The side of the abutment surface  232  that is not visible in  FIG. 11D  has a spring mounting pin like the pin  242  integrally formed on the compression spring anchor piece  238 . This spring mounting pin rides inside the opposite end of the compression spring  240 , thereby trapping the compression spring  240  between the compression spring anchor piece  238  and the compression spring slider piece  222 . When thus mounted, the compression spring slider piece  222  is prevented from sliding off the second battery pack mounting bracket  22  by the interaction between the range-limiting bracket  234  and the upright wall  236 , and the interaction between the first lip  258  and second lip  260  of the slider piece  222  in the first groove  254  and second groove  256 , respectively, of the second battery pack mounting bracket  22 . 
   The slider piece  222  may, however, slide toward and away from the compression spring anchor piece  238  a predetermined amount by applying varying amounts of pressure to the abutment surface  232  and thereby compressing the compression spring  240  or permitting it to expand. The arrangement depicted in  FIG. 11D  thereby maintains longitudinal pressure on the battery tube end caps  210 ,  214 , which enhances the battery tube&#39;s ability to maintain a complete electrical circuit. 
     FIG. 12  shows a cross-sectional view of the gear motor  144  and the circuit board housing  274 , which protects a circuit board  276  (see  FIG. 16 ) that controls operation of the gear motor  144 . In the preferred embodiment, the gear motor  144 , which is powered through first and second power terminals,  145 ,  147 , respectively, is a reversible, direct current (dc) motor. Also shown in  FIG. 12  is a signal receiver  278  and a manual operation switch  280 . As shown in  FIG. 13 , the circuit board housing  274  includes ports that accommodate the signal receiver  278  and a plug  282 . Depending upon the particular mounting of the retractable covering  14 , the signal receiver  278  and the plug  282  may be interchanged to facilitate the clearest line of sight from the remote control  18  to the signal receiver  278 . 
   Referring now to  FIGS. 14 and 15 , additional details concerning the drive end of the head rail  12  are visible. A power connection port  272  is visible in  FIG. 14 . When the power supply  24  is properly mounted on the head rail  12  as previously described, a plug  270  (visible in  FIG. 3 ) connected to the first wire lead  224  and the second wire lead  226  is plugged into the power connection port  272  shown adjacent the circuit board housing  274  in  FIG. 14 . The power connection port  272  is connected by a ribbon cable  284  to the circuit board  276  inside of the circuit board housing  274 . The gear motor  144  shown in  FIG. 12  has a gear shaft  286  attached to it. The gear shaft  286  is clearly visible in  FIG. 15 . The distal end of the gear shaft includes a pair of locking tabs  288 . Surrounding a portion of the gear shaft  286  is a motor gear  290 . In the preferred embodiment, the motor gear  290  comprises fifteen teeth or splines. In the preferred embodiment, three orbiting transfer gears  292  slide onto corresponding dowels or pivot pins  294  mounted at equal intervals around the motor gear  290  so as to meshingly engage the motor gear  290 . In the preferred embodiment, the orbiting transfer gears  292  each comprises twenty-one teeth or splines. Subsequently, an internal gear  296  is slid over the orbiting transfer gears  292  so that the internal gear  296  meshes with the three orbiting transfer gears  292 . In the preferred embodiment, the internal gear  296  comprises fifty-eight teeth or splines. When the internal gear  296  is sufficiently slid onto the orbiting transfer gears  292 , the pair of locking tabs  288  on the distal end of the gear shaft  286  retain the internal gear  296  in position. As shown to good advantage in  FIGS. 14 and 15  (see also  FIGS. 21 and 22 ), the internal gear  296  has extended ribs  297  on its outer surfaces  299 . These extended ribs  297  ride in an alignment channel  301  comprising part of the roll bar  138 . Thus, when the gear motor  144  drives the internal gear  296 , that in turn drives the roll bar  138  through the interaction between the extended ribs  297  and the alignment channel  301 . A plurality of smaller ribs  303  ride on the inner surface of the roll bar  138  when it is mounted on the internal gear  296 . 
     FIG. 16  is an exploded isometric view of the circuit board  276  in the circuit board housing  274 . Clearly visible in  FIG. 16  is the signal receiver  278  and the signal receiver wiring  298  shown in two selectable positions. The signal receiver  278  may be mounted in either side of a circuit board housing cover  300 , depending upon the intended mounting location for the covering  14 . In the preferred embodiment, the signal receiver wiring  298  has a plug  302  soldered to it that plugs into an appropriate socket  304  on the circuit board  276 . The ribbon cable  284  that joins the circuit board  276  to the power connection port  272  ( FIG. 14 ) may be seen in  FIG. 16 . Also, a rotator counter  306  that provides required position information to the electronics may be seen in  FIG. 16 . 
     FIGS. 17 ,  18 ,  19 , and  20  show the primary features of the remote control  18 .  FIG. 17  is an isometric view of the top surface of the remote control  18 . Clearly visible in  FIG. 17  is a frequency selection switch  308 . In the preferred embodiment, it is possible to select one of two control frequencies so that more than one retractable covering  14  may be separately controlled by a single remote control  18 . Mounted just below the frequency selection switch  308 , as depicted, is a control rocker switch  310 . Also shown in  FIG. 17  is a control signal  312  emanating from the end of the remote control  18 .  FIG. 18  is an exploded isometric view of the back side of the remote control  14  showing a battery housing cover  314  and a locking tab  316  that holds the battery housing cover  314  in position over the three AAA batteries  318  used by the remote control  18  in the preferred embodiment.  FIG. 19  is a top view of the remote control  18  and shows further details of the control switches. In particular, the control rocker switch  310  includes a raised up arrow  320  and a recessed down arrow  322 . Since the up arrow  320  is slightly raised and the down arrow  322  is slightly recessed, it is possible to use the remote control  18  in low light or no light conditions. Also visible in  FIG. 19  is a transmission indicator LED  324 . When the up arrow  320  or down arrow  322  on the rocker switch  310  is pressed, the transmission indicator LED  324  lights so that the user knows that the remote control  18  is attempting to transmit a signal  312  to the receiver  278  mounted in the head rail  12 . Finally,  FIG. 20  shows an end view of the remote control  18  along line  20 - 20  of  FIG. 19 . Clearly visible in  FIG. 20  is the control signal transmitter port  326  (this port is also shown in phantom in  FIG. 19 ). The control signal  312  emanates from the transmitter port  326 . Thus, the transmitter port  326  must be aimed at the receiver  278  during transmission. 
     FIG. 21  depicts the limit stop  26  operating to prevent the roll bar  138  from over-rotating and thereby over-extending the covering  14 . As previously discussed, if the gear motor  144  attempts to over-extend the covering  14 , the forward extending stop rib  142  will engage the pocket  140  defined by the main body  113  and the curvilinear portion  136  of the working half  108  of the limit stop  26 . The locking engagement between the forward extending stop rib  142  and the pocket  140  prevents the roll bar  138  from continuing to rotate. When the roll bar  138  is thus stopped from rotating, the electronics continue to command the drive motor  144  to rotate the roll bar  138 , but no rotation results. After a short duration, the electronics realize that the gear motor  144  is stalled and command the gear motor  144  to stop attempting to extend the covering  14 .  FIG. 21  also clearly shows a first sheet-retention channel  305  retaining the first flexible sheet  28 , and a second sheet-retention channel  307  retaining the second flexible sheet  30 . 
   When the control system is commanded to retract the covering  14 , the forward extending stop rib  142  is easily rotated out of engagement (counterclockwise in  FIG. 21 ) with the pocket  140  on the underside of the limit stop  26  and, as the covering  14  is wound around the roll bar  138 , it rolls over the top of the forward extending stop rib  142 , thereby covering it. When the covering  14  is not fully extended, the forward extending stop rib  142  is covered or concealed by the covering  14 . Thus, if the system is commanded to extend the covering  14 , and the covering  14  is not yet fully extended, the curvilinear portions  136  of the stop limit  26  slide over the exterior surface of the covering  14 , and the forward extending stop rib  142  does not and cannot become trapped in the pocket  140  behind the curvilinear portions  136 . When the control system is operating properly, the forward extending rib  142  does not get caught in the pocket  140  since the control system commands extension of the covering  144  to stop before it attempts to over-rotate the roll bar  138  and over-extend the covering  14 . This latter, more typical, operation of the control system is shown in  FIG. 22 . 
   The general operation of the remotely controllable the retractable covering  10  of the present invention is described next. The covering  14  may be in the configuration depicted in  FIG. 24 , which is in its most retracted configuration. From this fully retracted configuration, the operation of the remotely controllable retractable covering  10  proceeds as follows. If the down arrow  322  on the remote control  18  is pressed and released one time, the gear motor  144  begins to drive the roll bar  138  to extend the covering  14  (i.e., clockwise as depicted in  FIGS. 21-24 ). If no additional buttons are pressed on the remote control  18 , the motor  144  continues to drive the roll bar  138  until the covering  14  is fully extended, but in a minimum transmissivity configuration (i.e., the vanes  32  between the first flexible sheet  28  and the second flexible sheet  30  are closed and blocking the maximum amount of light and air transmission through the covering). This configuration is not shown separately in the figures, but the bottom rail  16  would be in a position similar to that depicted in  FIG. 23 , and the covering  14  would be otherwise filly extended. Then, if the down arrow  322  is pressed and released a second time while the covering  14  is in the fully extended configuration, the gear motor  144  again rotates the roll bar  138  (clockwise as depicted in  FIG. 21 ) until the bottom rail  16  is horizontal and the transmissivity through the covering  14  is at a maximum (i.e., the vanes  32  between the first flexible sheet  28  and the second flexible sheet  30  are open in a substantially horizontal configuration). This configuration of the covering  14  is shown in  FIG. 22 . When the blind is in the resulting “fully opened” configuration, any further pressing of the down arrow  322  on the remote control  18  has no effect on the configuration of the covering  14 . 
   If, instead, the up arrow  320  on the remote control  18  is pressed and released one time while the covering  14  is in its fully opened configuration (the  FIG. 22  configuration), the gear motor  144  rotates the roll bar  138  until the covering  14  is in its “fully closed” configuration (i.e., until the vanes  32  between the first flexible sheet  28  and the second flexible sheet  30  are substantially vertical and block the maximum amount of light or air attempting to pass through the covering  14 ). This latter configuration change involves rotating the roll bar  138  in a counterclockwise direction as depicted in  FIG. 21 . The covering  14  then remains in its fully extended but minimally transmissive configuration until another button  320 ,  322  is pressed on the remote control  18 . If the up arrow  320  is again pressed and released, the gear motor  144  is commanded to drive the roll bar  138  until the covering  14  is in its fully retracted configuration (shown in  FIG. 24 ), which is the configuration from which operation of the retractable covering commenced in this example. 
   Whenever the covering  14  is in motion, that motion may be interrupted by pressing and releasing either the up arrow  320  or the down arrow  322  on the remote control  18 . The up-and-down operation of the covering  14  and the transmissivity-adjustment of the covering  14  may both be interrupted by pressing either the up arrow  320  or the down arrow  322  on the remote control  18 . For example, if the gear motor  144  has been commanded to extend the covering  14 , and the bottom rail  16  is traveling downward but has not yet reached its lowest point of travel (see  FIG. 23 ), if either the up arrow  320  or the down arrow  322  on the remote control  18  is pressed and released, the gear motor  144  is commanded to cease all motion of the covering  14 . If the down arrow  322  is then pressed and released, the gear motor  144  will be commanded to continue extending the covering  14 . If, on the other hand, the up arrow  320  is pressed and released after the covering  14  was stopped, the gear motor  144  will be commanded to reverse the direction of rotation of the roll bar  138 , and will begin to retract the covering  14  onto the roll bar  138  (i.e., the roll bar  138  will be rotated in the counterclockwise direction as depicted in  FIGS. 21-24 ). Similarly, if the covering  14  is being retracted and the up arrow  320  or the down arrow  322  is pressed and released, retraction of the covering  14  stops. Then, if the up arrow  320  is pressed and released again, retraction of the covering  14  commences. If, on the other hand, the down arrow  322  is pressed and released after stopping the retraction of the covering  14 , the gear motor  144  will begin to rotate the roll bar  138  so as to extend the covering  14 . 
   Transmissivity of the extended covering  14  is also fully adjustable using the remote control  18 . When the covering  14  is in its fully extended configuration, the transmissivity of the covering  14  (i.e., the amount of light or air that is permitted to pass through the covering  14 ) may be adjusted by selectively pressing and releasing either the up arrow  320  or the down arrow  322 . When the covering  14  is in its fully extended configuration, the gear motor  144  operates in a second, slower speed. Therefore, the transmissivity adjustments take place at the slower speed. The counter  306  used to determine the position of the covering  14  commands the gear motor  144  to operate at the slower speed for a predetermined number of counts from the fully extended configuration of the covering  14 . The counter  306  is thus able to inform the gear motor  144  via the circuit board  276  when the covering  14  is configured for maximum transmissivity, minimum transmissivity, or any desired level of transmissivity between the maximum and the minimum. 
   The control system of the present invention uses counting as a primary means of controlling the position and orientation of the bottom rail  16  relative to the head rail  12 . In certain situations, the control system may place the gear motor  144  into a stall as a means of determining what configuration the covering  14  is in. For example, if the gear motor  144  attempts to over-extend the covering  14 , as depicted in  FIG. 21 , the forward extending stop rib  142  on the roll bar  138  will engage the pocket  140  behind the curvilinear portion  136  of the working half  108  of the limit stop  26 . If such capture of the forward extending stop rib  142  occurs, the gear motor  144  is thereby placed in a stall, which informs the circuitry that the gear motor  144  is attempting to over-rotate the roll bar  138  and over-extend the covering  144 . After being in a stall for a short period, the gear motor  144  is instructed to stop attempting to rotate the roll bar  138 . A second scenario where the gear motor  144  may be placed into a stall occurs when the covering  14  is fully retracted, as shown in  FIG. 24 . As shown, in the fully retracted configuration, an edge of the bottom rail  16  strikes the bottom rail stop arms  134  on the working half  108  of the limit stop  26 . This interaction between the bottom rail  16  and the stop arms  134  accomplishes two goals. First, when the gear motor  144  rotates the roll bar  138  sufficiently to drive an edge of the bottom rail  16  into the stop arms  134 , the curvilinear portions  136  on the underside, as depicted in  FIG. 9B , of the working half  108  of the limit stop  26  are thereby raised off the roll bar  138  and the covering material  14  that has collected thereon. Second, when the bottom rail  16  is captured by the bottom rail stop arms  134 , the gear motor  144  ultimately goes into a stall, and the control electronics recognize the stall and shut down the gear motor  144 . Thus, the covering  14  takes on its fully retracted configuration, wherein the bottom rail  16  holds the working half  108  of the limit stop  26  off of the actual covering material  14 , which prevents the curvilinear portions  136  which ride on the covering material  14  as it is retracted or extended from creasing or denting, which may otherwise occur if the covering  14  is kept in a fully retracted configuration over an extended period of time. 
   It is also possible to control the retractable covering apparatus of the present invention without using the remote control  18 . A manual operation switch  280  is mounted to the circuit board housing  274  and circuit board housing cover  300  (see  FIGS. 12 and 13 , for example). Selective pressing of the manual operation switch  280  permits a user to configure the covering  14  in any desired configuration that is obtainable through use of the remote control  18 . In general, with each press of the manual operation switch  280 , the control electronics on the circuit board  276  treat each press of the manual operation switch  280  as first a press of the up arrow  320  on the remote control  18  followed by a press of the down arrow  322  on the remote control  18 , or vice versa. In other words, each time the manual operation switch  280  is pressed, the control electronics interpret that as alternating presses of the up arrow  320  and down arrow  322  on the remote control  18 . An exception to this general rule by which the control electronics interpret the presses of the manual operation switch  280  occurs when the covering  14  is in its fully extended configuration. When the covering  14  is in the fully extended configuration, the control electronics must determine whether the user is attempting to retract the covering  14  or merely adjust the transmissivity of the fully extended covering  14 . For example, if the covering  14  is in its fully extended configuration and its minimally transmissive configuration (i.e., the covering  14  has just reached its fully extended configuration and stopped), a subsequent press of the manual operation switch  280  is interpreted by the control electronics as a command to “open” the extended covering  14 , increasing the transmissivity thereof by rotating the roll bar  138  to move the vanes  32  to a more horizontal configuration. If the manual operation switch  280  is again pressed during adjustment of the transmissivity, the gear motor  144  is signaled to stop movement. If the covering  14  is thus placed in a configuration somewhere between its maximally transmissive configuration and its minimally transmissive configuration, a subsequent press and release of the manual operation switch  280  will either increase the transmissivity or decrease the transmissivity depending upon whether the transmissivity was increasing or decreasing when the manual operation switch  280  was pushed to stop motion of the gear motor  144 . If the transmissivity was being increased when the gear motor  144  was commanded to stop rotating the roll bar  138 , a subsequent press and release of the manual operation switch  280  will instruct the control electronics to command the gear motor  144  to continue increasing the transmissivity as long as the maximum transmissivity configuration had not yet been achieved. If, on the other hand, the transmissivity was being reduced when the manual operation switch  280  was pressed to stop rotation of the roll bar  138 , a subsequent press and release of the manual operation switch  280  will cause the control electronics to instruct the gear motor  144  to rotate the roll bar  138  to continue decreasing the transmissivity until the minimum transmissivity configuration is obtained or the manual operation switch  280  is again pressed, whichever occurs first. 
   In summary, if the manual operation switch  280  is pressed while the gear motor  144  is rotating the roll bar  138  and the covering  14  has not yet reached a fully extended or fully retracted configuration, the gear motor  144  will be commanded to stop rotating the roll bar  138 . A subsequent press and release of the manual operation switch  280  will reverse the direction of rotation of the roll bar  138 . 
   For example, if the covering  14  was being extended before the gear motor  144  was instructed to stop rotating the roll bar  138 , a subsequent press and release of the manual operation switch  280  will result in the gear motor  144  rotating the roll bar  138  so as to retract the covering  14 . On the other hand, if the gear motor  144  was driving the roll bar  138  so as to retract the covering  14  when the manual operation switch  280  was pressed to stop retraction of the covering  14 , a subsequent press and release of the manual operation switch  280  will cause the control electronics to command the gear motor  144  to rotate the roll bar  138  so as to extend the covering  14 . When the covering  14  is in the fully extended configuration (see  FIGS. 1 and 22 ), pressing and releasing the manual operation switch  280  does not necessarily reverse the direction of rotation of the roll bar  138 . The direction of rotation of the roll bar  138  is only reversed if the transmissivity has reached a maximum before the manual operation switch  280  is pressed and released two times. For example, if the transmissivity is being increased, but has not yet reached the maximum transmissivity configuration, when the manual operation switch  280  is pressed and released, rotation of the roll bar  138  stops. If the manual operation switch  280  is again pressed and released, the roll bar  138  is rotated in the same direction that it was previously rotating until the maximum transmissivity configuration is obtained. Thus, the direction of rotation of the roll bar  138  is not always reversed following an interruption or stopping of the motion of the roll bar  138  while adjusting transmissivity (i.e., while the covering  14  is in its fully extended configuration). 
     FIG. 25A  is a block diagram of the control system electronics.  FIGS. 25B and 25C  are schematic diagrams of the control system electronics. The electronics are described next using  FIGS. 25A ,  25 B, and  25 C. Input power for the electronics is supplied by one or more batteries  208  connected in series. Connected between the battery  208  and the microprocessor  328  is circuitry  330  that provides battery reversal protection, a voltage regulator, noise filters, and a fuse to an H bridge. The voltage regulator is always on, and the quiescent current for the regulator is about one micro amp. A resistor R 1  and two capacitors C 2  and C 5  together filter motor noise and prevent it from affecting the voltage regulator. A third capacitor C 3  provides additional power filtering. Finally, the fuse F 1  provides fault protection to the H bridge circuit. The microprocessor  328  has a built in “watch dog” timer that is used to wake up the microprocessor from sleep mode. Resistor R 2  and capacitor C 4  form an oscillator at nominally 2.05 MH (.+−0.25%). Resistor R 0  allows for in-circuit programming. 
   The receiver  278  in the preferred embodiment is a 40 KHz infrared receiver connected to terminals P 3  and P 4 . Power is supplied to the receiver directly from the microprocessor  328 . The output from the receiver  278  (high when idle, low when a valid signal is being received) is connected to the microprocessor  328 . An external photo-eye may be connected to terminal P 2  (to board via jumper J 1 - 2 ). It is automatically used as soon as it is connected (and the internal photo-eye is then ignored). Switch S 1  is the manual operation switch  280 , which is shown, for example, in  FIG. 13 . A slotted optical sensor  306  is mounted for rotation with the roll bar  138 . A light emitter used in conjunction with the slotted optical sensor  306  is on only when the microprocessor  328  needs to check the sensor  306 , and is driven by the microprocessor  328  with current limiting resistor R 3 . The output of the sensor (an open collector transistor) is connected to a microprocessor pin with an internal pull-up resistor. 
   Three leads from the microprocessor  328  control the H bridge: LEFT (left N MOSFET), RIGHT (right N MOSFET), and RUN (which turns on the appropriate P MOSFET). The N MOSFETs (QIA and B) are turned on by placing five volts on the gate. A P MOSFET (Q 2 A or B) will be turned on when the RUN signal is high and either LEFT or RIGHT is low. When this happens, Q 3 A or B will turn on and pull the gate of Q 2 A or B to ground, which turns it on (R 4 A or B pulls the gate to the same level as the source, and keeps the P MOSFET off). This setup only allows a P MOSFET to be on if the N MOSFET on the same side is off. If both LEFT and RIGHT are low when RUN is active, then both P MOSFETs will turn on and act as a brake. 
   Diodes internal to the P MOSFETs provide protection from back EMF from the motor. The output of the H bridge connects to the motor via jumper J 3 - 4 , then via connector P 5  or P 6  depending on left versus right-hand operation. Capacitor C 5  filters some of the high frequency noise from the motor. 
   All times discussed in the present specification are nominal; actual times vary by .+−0.25%. Also when the IR receiver is turned on, during the first millisecond (msec) of the interval the output is ignored to allow the unit to settle. 
   The following discusses the modes of operation of the microprocessor  328 . 
   Normal sleep/wake operation: Microprocessor  328  wakes up and checks the override button. If it is not pushed, the IR receiver  278  is turned on for 5.5 msec. Any active IR signal will cause the receiver  278  to be turned on again for 55 msec looking for a valid signal. 
   In sleep, the N MOSFETs are both on (brake), the P MOSFETs are off, the opto-sensor LED is off, the IR receiver  278  power and signal leads are driven low, and the option and manual switches are driven low. This is the minimal power state. Sleep lasts nominally 300 msec (210 minimum-480 maximum). This time is set by an RC timer inside the microprocessor  328  and is independent of the clock. 
   If the override button was pushed, then the IR receiver  278  is not turned on yet. The motor will be activated in the opposite direction from the last movement, and then the IR receiver  278  will start cycling (see below). 
   If any signals are present during the 5.5 msec test interval, then the receiver  278  stays off for 9.5 msec (during this time no other components are on besides the microprocessor  328 ). Then the receiver  278  is turned on for 55 msec. During this time, the receiver  278  is checked every 160.mu.sec. This data is checked by a state machine. At the end of the interval, the receiver  278  is shut off. If a valid sequence (our channel either up or down) was not received, then the microprocessor  328  goes back to a sleep mode. 
   If a valid up (down) command was received, and the upper (lower) limit has not been reached, then the motor  144  is turned on going up (down). If the command was up (down), and the upper (lower) limit has been reached, then the remote button is checked to determine if it is held for more than 1.7 seconds. If so, then the limit is over-ridden and the motor  144  starts in the appropriate direction. If it later stalls, a new limit will be set. During this check, the microprocessor  328  stays on the entire time, and the receiver  278  is cycled 9.5 msec off, 55 msec on. 
   Motor running: The receiver  278  is cycled 9.5 msec off, 55 msec on. After the on time, the status is checked: (1) the button is still held from when the motor  144  started (leave motor running); (2) the button has been released (leave motor running); or (3) the button has been re-pushed which means stop (see below). In a similar fashion the manual override button is checked every cycle. If the opto-sensor  306  changes state, then the stall timer is reset and the revolution counter is updated depending on the direction the motor  144  and hence the covering are moving. If the covering is moving up, then it is checked to determine if it reached the upper limit, and if so, then the motor  144  is stopped. If the lower limit is reached and the covering is moving down, then the motor  144  is stopped. Finally, the stall timer is checked. If it expires, then the motor is stopped and a new limit is set. 
   Stop: The P MOSFETs are turned off, and after 1 msec, the N MOSFETs are both turned on (brake), then the manual pushbutton and the IR remote are checked to determine that they are no longer pushed, then the microprocessor  328  reverts to a sleep mode. 
     FIGS. 26 ,  27 ,  28 ,  29 ,  30 ,  31 , and  32  together comprise a flow chart representation of the logic used by the control system of the present invention. The logic may be implemented in software or firmware for execution by the microprocessor  328 . All times shown in the flow chart are nominal. Actual times may vary in the preferred embodiment by .+−0.25%. Items in a box are actions that are performed. Items in a diamond are tests that are made and the possible outcomes are written next to the arrows leaving the diamond. An arrow to a number goes to that number on another figure. 
   The following ten scenarios provide insight into how the control system electronics follow the logic depicted in  FIGS. 26 ,  27 ,  28 ,  29 ,  30 ,  31 , and  32 . 
   Scenario 1: Batteries  208  first inserted, no buttons pushed. Execution starts with item  400  in  FIG. 26 , then  402  to initialize the system. The system then stays in the idle loop with items  404 ,  410 ,  416 , and  420 . 
   Scenario 2: Covering  14  not fully closed, motor  144  is stopped, the down button  322  on the transmitter  18  is pushed and released, and the user lets it go to the transition point. We are somewhere in the idle loop  404 ,  410 ,  426 ,  420  When item  412  completes, the result of the test will be yes, moving to condition  2  (i.e., from element  414  on  FIG. 26  to element  432  on  FIG. 27 . Item  434  ( FIG. 27 ) will cycle the IR sensor  278 , which will decode the button, and we move to condition  4  (i.e., from element  448  on  FIG. 27  to element  458  on  FIG. 28 ), which executes items  460  and  462 , which starts the motor  144  going down, full speed, and we move to condition  7  (i.e., from element  464  on  FIG. 28  to element  490  on  FIG. 30 ). We are now in a loop doing item  492 . As the motor  144  turns, the rotating sensor  306  will change, causing us to go to condition  8  (i.e., from element  496  on  FIG. 30  to element  512  on  FIG. 31 ), and item  520  where we decrement the rotation counter. Assuming we do not reach the transition point, we move back to condition  7  (i.e., from element  546  on  FIG. 31  to element  490  on  FIG. 30 ) and the loop doing item with the motor  144  running at full speed. Task number  1  in item  492  will cause the system to check if the button  310  on the transmitter  18  is still pushed. When it is released, this is noted. The motor  144  continues, and we go back to the loop doing item  492 . Finally, the covering  14  reaches the transition point. We go through items  514 ,  520 ,  524 ,  532 ,  536  ( FIG. 31 ) and condition  10  (i.e., we move from element  542  of  FIG. 31  to element  506  of  FIG. 30 ), and item  508  which stops the motor  144  and puts us back in the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). 
   Scenario 3: Covering  14  not fully closed, motor  144  is stopped, the down button  322  on the transmitter  18  is pushed then released, and the user lets it go awhile, then pushes the button  322  again to stop the covering  14  partially closed. We got to the loop doing item  492  ( FIG. 30 ) the same as scenario  2 . Task number  1  in item  492  will cause the system to check if the button  322  on the transmitter  18  is still pushed. When it is released, this is noted. The motor  144  continues, and we go back to the loop doing item  492 . When the button  322  is re-pushed, this same task takes us to condition  10  where we go to item  508 , where we stop the motor  144 . We stay in item  508  until the button is released. Then we go back to the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). 
   Scenario 4: Covering  14  not fully closed, motor  144  is stopped, the up button  320  on the transmitter  18  is pushed and released, and the user lets it go to the top limit. We are somewhere in the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). When item  410  completes, the result of the test in item  412  will be “yes,” moving to condition  2  (i.e., we move from element  414  of  FIG. 26  to element  432  of  FIG. 27 ). Item  434  will cycle the IR sensor  278 , which will decode the button  320 , and we move to condition  3  (i.e., we move from element  452  in  FIG. 27  to element  454  of  FIG. 28 ), which executes items  456  and  462 , which starts the motor  144  going up, full speed, and we now transfer from element  464  of  FIG. 28  to element  490  of  FIG. 30 . We are now in a loop doing item  492 . As the motor  144  turns, the rotation sensor will change, causing us to go to condition  8  (i.e., from element  496  of  FIG. 30  to element  512  of  FIG. 31 ) and item  518 , where we increment the rotation counter  306 . Assuming we do not reach the top, we go back to the loop doing item  492  ( FIG. 30 ) with the motor  144  running at full speed. Task number  1  in item  492  will cause the system to check if the button  320  on the transmitter  18  is still pushed. When it is released, this is noted. The motor  144  continues and we go back to the loop doing item  492 . Finally, the covering  14  reaches the upper limit. We go through items  514 ,  518 ,  526  ( FIG. 31 ) and condition  10  (i.e., from element  530  of  FIG. 31  to element  506  in  FIG. 30 ), and item  508 , which stops the motor  144  and puts us back in the idle loop  404 ,  410 ,  416 ,  420 . 
   Scenario 5: Covering  14  not fully open, motor  144  is stopped, the up button  320  on the transmitter  18  is pushed then released, and the user lets it go awhile, then pushes the button  320  again to stop it partially open. We get to the loop doing item  492  ( FIG. 30 ) the same as scenario  4 . Task number  1  in item  492  will cause the system to check if the button  320  on the transmitter  18  is still pushed. When it is released, this is noted. The motor  144  continues, and we go back to the loop doing item  492 . When the button  320  is re-pushed, this same task takes us to condition  10  where we go to item  510 , where we stop the motor  144 . We stay in item  510  until the button  320  is released. Then we go back to the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). 
   Scenario 6: Covering  14  at top limit, motor  144  is stopped, the up button  320  on the transmitter  18  is pushed and held until the limit is over-ridden, and the user lets it go to the top stall (or stalls it partially open to set a new upper limit). We are somewhere in the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). When item  410  completes, the result of the test in item  412  will be “yes,” moving to condition  2  (i.e., from element  414  in  FIG. 26  to element  432  in  FIG. 27 ). Item  434  will cycle the IR sensor  278 , which will decode the button  320 , and we move to condition  4  (i.e., from element  448  in  FIG. 27  to element  458  in  FIG. 28 ), which executes item  460  and  462 , which starts the motor  144  going down, full speed. We are now in a loop doing item  492  ( FIG. 30 ). As the motor  144  turns, the rotation sensor will change, causing us to go to condition  8  (i.e., from element  496  on  FIG. 30  to element  512  on  FIG. 31 ) and item  520 , where we decrement the rotation counter  306 . Assuming we do not reach the bottom, we go back to the loop doing item  492  with the motor  144  running at full speed. When the motor  144  reaches the top, or for any other reason stops rotating (stalls), the stall timer will time-out, and we go to condition  9  (i.e., from element  500  in  FIG. 30  to element  548  in  FIG. 32 ). We execute item  552  to set the new upper limit, then go to item  508  ( FIG. 30 ), where we stop the motor  144 . Then we go back to the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). Task number  1  in item  492  ( FIG. 30 ) will cause the system to check if the button on the transmitter  18  is still pushed. When it is released, this is noted. The motor  144  continues and we go back to the loop doing item  492 . 
   Scenario 7: Brand new covering  14  not at bottom, motor  144  is stopped, the down button  322  on the transmitter  18  is pushed and released, and the user lets it go to the bottom stall. We are somewhere in the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). When item  410  completes, the result of the test in item  412  will be “yes,” moving to condition  2  (i.e., from element  414  in  FIG. 26  to element  432  of  FIG. 27 ). Item  434  will cycle the IR sensor  278 , which will decode the button  322 , and we move to condition  4  (i.e., from element  448  of  FIG. 27  to element  458  of  FIG. 28 ) which executes item  460  and  462 , which starts the motor  144  going down, full speed. We are now in a loop doing item  492  ( FIG. 30 ). As the motor  144  turns, the rotation sensor will change, causing us to go to condition  8  (i.e., from element  496  of  FIG. 30  to element  512  of  FIG. 31 ) and item  520 , where we decrement the rotation counter  306 . Assuming we do not reach the bottom, we go back to the loop doing item  492  ( FIG. 30 ) with the motor  144  running at full speed. When the motor  144  reaches the bottom, or for any other reason stops rotating (stalls), the stall timer will time-out, and we go to condition  9  (i.e., from element  500  of  FIG. 30  to element  548  of  FIG. 32 ). We execute item  554  ( FIG. 32 ) to set the new lower limit and transition point, then go to item  508  ( FIG. 30 ) where we stop the motor  144 . Then we go back to the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). Task number  1  in item  492  ( FIG. 30 ) will cause the system to check if the button  322  on the transmitter  18  is still pushed. When it is released, this is noted. The motor  144  continues and we go back to the loop doing item  492 . 
   Scenario 8: Covering  14  fully closed, motor  144  is stopped, the down button  322  on the transmitter  18  is pushed unintentionally and released quickly. We are somewhere in the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). When item  410  completes, the result of the test in item  412  will be “yes,” moving to condition  2  (i.e., from element  414  of  FIG. 26  to element  432  of  FIG. 27 ). Item  434  will cycle the IR sensor  278 , which will decode the button  322 , and we move to condition  5  (i.e., from element  446  of  FIG. 27  to element  466  of  FIG. 29 ), which starts the loop running item  468 . When the user realizes the covering  14  is already down and releases the button  322 , we go to the idle loop  404 ,  410 ,  426 ,  20  ( FIG. 26 ). 
   Scenario 9: Covering  14  fully open, motor  144  is stopped, the up button  320  on the transmitter  18  is pushed unintentionally and released. We are somewhere in the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). When item  410  completes, the result of the test in item  412  will be “yes,” moving to condition  2  (i.e., from element  414  of  FIG. 26  to element  432  of  FIG. 27 ). Item  434  will cycle the IR sensor  278 , which will decode the button  320 , and we move to condition  6  (i.e., from element  450  in  FIG. 27  to element  478  in  FIG. 29 ), which starts the loop running item  480 . When the user realizes the covering  14  is already down and releases the button  320 , we go to the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). 
   Scenario 10: Same as scenarios 2-6 but the manual button  280  is pushed instead of the IR button  310 . Instead of moving to condition  2  we go to condition  1  (i.e., from element  408  in  FIG. 26  to element  422  in  FIG. 27 ). We then go the opposite way that we moved last time. We then go to condition  3  (i.e., from element  428  in  FIG. 27  to element  454  in  FIG. 28 ) or  4  (i.e., from element  430  in  FIG. 27  to element  458  in  FIG. 28 ) just like we pushed the appropriate button on the remote  18 . We get to loop doing item  492  ( FIG. 30 ), and the scenarios are the same except we note the manual button  280  is released instead of the remote button  310 . If the manual button  280  is re-pushed (as in scenario  3  or  5 ), then we execute item  508 , which stops the motor  144 , and then we go to the idle loop  404 ,  410 ,  416 ,  420  ( FIG. 26 ). 
   Although preferred embodiments of this invention have been described above, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. Further, all directional references (e.g., up, down, leftward, rightward, bottom, top, inner, outer, above, below, clockwise, and counterclockwise) used above are to aid the reader&#39;s understanding of the present invention, but should not create limitations, particularly as to the orientation of the apparatus. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting.