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CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European Application No. 04075018.4 filed 13 Jan. 2004. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a retractable blind assembly for covering an irregularly shaped window area with an upper triangular portion and a lower rectangular portion. This invention particularly relates to a blind which can be retracted and extended by pulling and releasing a plurality of pull cords. 
     2. Description of the Relevant Art 
     It has been a continuing problem to provide retractable cord-operated blinds for covering irregularly shaped windows although solutions had been readily devised for strictly triangular and trapezoidal windows. Polygonal windows of the kind having a generally rectangular outline but with a corner “cut off” have been the most difficult to cover. 
     Among the attempts to develop suitable retractable cord-operated blinds for such windows with an upper triangular portion and lower rectangular portion are the blinds described in EP 0 532 036, EP 0 674 091 and EP 1 120 534. However, such blinds have not been easy to assemble. Moreover, the configuration and size of the windows that could be provided with such blinds have often been limited. 
     SUMMARY OF THE INVENTION 
     In order to provide a retractable blind assembly for covering a window area with an upper triangular portion and a lower rectangular portion that is easier to assemble and can be used with more configurations and sizes of windows, this invention relates to a blind ( 1 ), including:
         a top section with a vertically-extending blind covering material extending between a fixed inclined head rail and a middle rail that is pivotable with respect to the head rail about a pivot center that is adjacent to a lowermost end of the head rail; the head rail extending upwardly at an acute angle; the middle rail being pivotable between a lower position, in which the middle rail extends horizontally, when the covering material is extended and an upper position, in which the middle rail extends upwardly at an acute angle and is adjacent the head rail, when the covering material is retracted; the covering material in the top section having a generally triangular shape with an unattached short apex about the pivot center and an opposite, unattached, long side when the covering material is extended;   a bottom section with the covering material extending between the middle rail and a horizontally-extending bottom rail; the bottom rail being movable vertically between the bottom of the blind when the covering material is extended and an upper position, adjacent the middle rail, when the covering material is retracted;   at least first and second lift cords for extending and retracting the covering material; the lift cords being connected outside the blind to a cord connector;
 
characterized in that the first lift cord is routed through the top section adjacent its apex and long side and the second lift cord is routed such that it passes through the top section between its apex and long side, and wherein when the covering material is extended, the total length of the first lift cord within the top section is equal to the total length of the second lift cord within the top section.
       

     Further aspects of the invention will be apparent from the detailed description below of particular embodiments and the drawings thereof, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a first embodiment of a retractable blind assembly of this invention, with its pleated covering material extended; 
         FIG. 2  is a schematic view of a second embodiment of a retractable blind assembly of this invention, with its pleated covering material extended; and 
         FIG. 3  is a schematic view of the second embodiment of a retractable blind assembly of  FIG. 2 , with its covering material partially retracted. 
         FIG. 4  is a schematic view of a third embodiment of a retractable blind assembly of this invention, with its pleated covering material extended; 
         FIG. 5  is a schematic view of a fourth embodiment of a retractable blind assembly of this invention, with its pleated covering material extended; 
         FIG. 6  is a schematic view of a fifth embodiment of a retractable blind assembly of this invention, with its pleated covering material extended; 
         FIG. 7  is a schematic view of a sixth embodiment of a retractable blind assembly of this invention, with its pleated covering material extended; and 
         FIG. 8  is a schematic view of a seventh embodiment of a retractable blind assembly of this invention, with its pleated covering material extended. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a retractable cord-operated blind  1  with a fixed inclined head rail or top rail  5  as a support structure and a raisable horizontally-extending bottom rail  11 . Between the head rail  5  and bottom rail  11  is a middle rail  7  that is pivotable with respect to the head rail  5  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  5 ,  7 ,  11  are a pair of lift cords  17 ,  19  which extend, between the rails, through perforations in a covering member  23 . The top and bottom edges of the covering member  23  are attached to the top and bottom rails  5  and  11 , and a middle portion of the covering member is attached to the middle rail  7 . 
     The covering material  23  has a generally triangular top portion and a generally rectangular bottom portion, and it is preferably made from a pleated material. The head rail  5  and middle rail  7  and the triangular top portion of the covering member  23 , attached to them, form a top section  3  of the blind  1 . The covering material  23  in the top section  3  has an unattached short apex  13  about the pivot center of the top section and an opposite, unattached, long side  15  when the covering material is extended. The middle rail  7  and bottom rail  11  and the rectangular bottom portion of the covering member  23 , attached to them, form a bottom section  9  of the blind  1 . 
     The blind  1  has a vertically-movable cord collector  21  outside of the blind. Attached to the cord connector  21  are both ends  20 , 22  of each of a pair of lift cords  17 ,  19 . The lift cords  17 ,  19  extend from, and return to, the common cord collector  21  and are routed through, and deflected by, the head, middle and bottom rails  5 ,  7 ,  11  as shown in  FIG. 1 . A depending cord member  25  can manually actuate the collector  21 . In this regard, the cord member  25  can be used to raise and lower the collector  21  to raise and lower the middle and bottom rails  7 ,  11  and thereby retract and extend the covering member  23  as described below. 
     The routing of the first lift cord  17  in the blind  1  in accordance with this invention is as follows (with reference to  FIG. 1 ). The first lift cord  17  extends rightwardly through the head rail  5 , away from the collector  21 , and at a first guide in the bottom of the head rail, the first lift cord  17  extends downwardly to a first guide through the middle rail  7  that is adjacent—i.e., just to the right of—the apex  13  of the covering material  23  in the top section  3  and adjacent the left end of the middle rail. The first lift cord  17  then extends downwardly through the middle rail  7  to a first guide in the top of the bottom rail  11 , adjacent its left end, and then rightwardly through the bottom rail to a second guide in the top of the bottom rail. The first lift cord then extends upwardly to a second guide in the bottom of the middle rail  7 , midway between its ends, and then rightwardly through the middle rail to a third guide in the top of the middle rail, adjacent its right end. The first lift cord then extends upwardly, adjacent to—i.e., just to the left of—the long side  15  of the covering material  23  in the top section  3 , to a second guide in the bottom of the head rail  5  and then leftwardly through the head rail back to the collector  21 . 
     The routing of the second lift cord  19  in the blind  1  in accordance with this invention is as follows (with reference to  FIG. 1 ). The second lift cord  19  also extends rightwardly through the head rail  5 , away from the collector  21 , and at a third guide in the bottom of the head rail—midway between the first and second guides in the head rail—the second lift cord  19  extends downwardly to a fourth guide through the middle rail  7 . The fourth guide in the middle rail  7  can be adjacent to—i.e., just to the left of—the second guide in the middle rail as shown schematically in  FIG. 1 , but preferably, the second and fourth guides in the middle rail are coaxial. The second lift cord  19  then extends downwardly through the fourth guide in the middle rail to a third guide in the top of the bottom rail  11 . The third guide in the top of the bottom rail  11  can be adjacent to—i.e., just to the left of—the second guide in the bottom rail as shown schematically in  FIG. 1 , but preferably, the second and third guides in the bottom rail are coaxial. The second lift cord then extends rightwardly through the bottom rail to a fourth guide in the top of the bottom rail, adjacent its right end. The second lift cord then extends upwardly to a fifth guide in the bottom of the middle rail  7 , adjacent its right end, and then leftwardly through the middle rail to a sixth guide in the top of the middle rail  7 . The sixth guide in the middle rail  7  can be adjacent to—i.e., just to the right of—the fourth guide in the middle rail as shown schematically in  FIG. 1 , but preferably, the sixth guide in the middle rail is coaxial with the second and fourth guides in the middle rail. The second lift cord then extends upwardly to a fourth guide in the bottom of the head rail  5  and then leftwardly through the head rail back to the collector  21 . The fourth guide in the head rail  5  can be adjacent to—i.e., just to the right of—the third guide in the head rail as shown schematically in  FIG. 1 , but preferably, the third and fourth guides in the head rail are coaxial. 
     Thus, as seen from  FIG. 1 , the first lift cord  17  is routed through the top section  3  of the blind  1  adjacent the apex  13  and long side  15  of the covering material  23  in the top section. The second lift cord  19  is routed through the top section  3  between the apex and long side  13 , 15  of the covering material  23  in the top section. The total length of the first lift cord  17  within the top section  3  is equal to the total length of the second lift cord  19  within the top section  3  when the covering material is extended. 
     Preferably a spring  27  is also provided in the head rail  5 . The left end of the spring  27  is attached to the left end of the head rail, and the right end of the spring is attached to one end of a support wire  29 . The support wire  29  extends, within the head rail  5 , rightwardly away from the spring to a fifth guide in the bottom of the head rail, adjacent its right end. The support wire  29  then extends downwardly to the right end of the middle rail  7  where the other end of the support wire  29  is attached. The spring  27  and support wire  29  prevent the right end of the middle rail  7  from pivoting downwardly below the left end of the middle rail, i.e., below horizontal. 
     When the cord member  25  is pulled downwardly, the cord collector  21  pulls the first and second pull cords  17  and  19  outwardly of the blind  1 . This initially causes the first pull cord  17  to pull up the bottom rail  11  at its first and second guides and the second pull cord  19  to pull up the bottom rail  11  at its third and fourth guides until the middle and bottom rails are vertically adjacent to one another. Pulling the cord member  25  is further downwardly causes the first pull cord to pull up the middle rail  7  at its second and third guides and the second pull cord to pull up the middle rail at its fourth and fifth guides, while the first pull cord pulls up the bottom rail further at its first and second guides and the second pull cord pull up the bottom rail further at its third and fourth guides, so that both the middle and bottom rails pivot about the pivot center of the middle rail. 
       FIGS. 2 and 3  show a second embodiment of a blind  101  which is similar to the blind  1  of  FIG. 1  and for which corresponding reference numerals (greater by  100 ) are used below for describing the same parts or corresponding parts. 
     The blind  101  includes a fixed inclined head rail  105  and a raisable horizontally-extending bottom rail  111 . Between the head rail  105  and bottom rail  111  is a middle rail  107  that is pivotable with respect to the head rail  105  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  105 ,  107 ,  111  are a pair of lift cords  117 ,  119  which extend, between the rails, through perforations in a covering member  123 , attached to the top, middle and bottom rails. 
     The head rail  105  and middle rail  107  and the triangular top portion of the covering member  123 , attached to them, form a top section  103  of the blind  101  with an unattached short apex  113  about the pivot center of the top section and an opposite, unattached, long side  115  when the covering material is extended. The middle rail  107  and bottom rail  111  and the rectangular bottom portion of the covering member  123 , attached to them, form a bottom section  109  of the blind  101 . 
     The blind  101  has a vertically-movable cord collector  121  with a depending cord member  125  outside of the blind. Two lift cords  117 ,  119  are attached to the cord collector  121  and are routed through, and deflected by, the head, middle and bottom rails  105 ,  107 ,  111  as shown in  FIGS. 2 and 3 . Both ends of one of the lift cords  117  are attached to the collector. The other lift cord  119  comprises two lift cord parts  119 A and  119 B, and one end  120  of each lift cord part is attached to the collector and the other end  122  is fixed to the bottom rail  111 . The cord member  125  can be used to raise and lower the collector  121  to raise and lower the middle and bottom rails  107 ,  111  and thereby retract and extend the covering member  123  as described below. 
     The routing of the first lift cord  117  in the blind  101  in accordance with this invention is as follows (with reference to  FIGS. 2 and 3 ). The first lift cord  117  extends leftwardly through the head rail  105 , away from the collector  121 , to a first guide in the bottom of the head rail, adjacent its left end. The first lift cord  117  extends downwardly from the first guide in the head rail to a first guide in the top of the middle rail  107  that is adjacent—i.e., just to the right of—the apex  113  of the covering material  123  in the top section  103  and adjacent the left end of the middle rail. The first lift cord  117  then extends rightwardly through the middle rail  107  to a second guide in the bottom of the middle rail, adjacent its right end, and then extends downwardly around an upstanding wire loop  129  attached to the top of the bottom rail  111 , adjacent its right end. The first lift cord then extends upwardly from the wire loop  129  through a third guide in the middle rail, adjacent its right end. The third guide through the middle rail  107  can be adjacent—i.e., just to the right of—the second guide in the middle rail as shown schematically in  FIGS. 2 and 3 , but preferably, the second and third guides in the middle rail are coaxial. The first lift cord  117  then extends upwardly from the third guide in the middle rail adjacent to—i.e., just to the left of—the long side  115  of the covering material  123  in the top section  103 , to a second guide in the bottom of the head rail  105 , adjacent its right end. The first lift cord then extends rightwardly through the head rail, from its second guide, back to the collector  121 . 
     The routing of the separate parts  119 A and  119 B of the second lift cord  119  in the blind  101  in accordance with this invention is as follows (with reference to  FIGS. 2 and 3 ). 
     One lift cord part  119 A extends leftwardly through the head rail  105 , away from one of its end  120  and the collector  121 , and at a third guide in the bottom of the head rail—midway between the first and second guides in the head rail—it extends downwardly to a fourth guide in the top of the middle rail  107 . The one lift cord part  119 A then extends leftwardly through the middle rail  107  to a fifth guide in the bottom of the middle rail, adjacent its left end. 
     The fifth guide in the bottom of the middle rail  107  can be adjacent to—i.e., just to the right of—the first guide in the top of the middle rail as shown schematically in  FIGS. 2 and 3 , but preferably, the first and fifth guides in the middle rail are coaxial. The one lift cord part  119 A then extends downwardly through the fifth guide in the middle rail and its other end  122  is attached to the top of the bottom rail  111 , adjacent the left end of the bottom rail. 
     The other lift cord part  19 B also extends leftwardly through the head rail  105 , away from one of its end  120  and the collector  121 , and at a fourth guide in the bottom of the head rail—midway between the first and second guides in the head rail—it extends downwardly to a sixth guide through the middle rail  107 . The fourth guide in the bottom of the head rail can be adjacent to—i.e., just to the right of—the third guide in the bottom of the head rail as shown schematically in  FIGS. 2 and 3 , but preferably the third and fourth guides in the head rail are coaxial. The sixth guide in the middle rail can be adjacent to—i.e., just to the right of—the fourth guide in the middle rail as shown schematically in  FIGS. 2 and 3 , but preferably the fourth and sixth guides in the middle rail are also coaxial. The other lift cord part  119 B then extends downwardly through the sixth guide in the middle rail, and its other end  122  is fixed to the top of the bottom rail, midway between the ends of the bottom rail. 
     Thus, as seen from  FIGS. 2 and 3 , the first lift cord  117  is routed through the top section  103  of the blind  101  adjacent the apex  113  and long side  115  of the covering material  123  in the top section. The parts of the second lift cord  119  are routed through the top section  103  between the apex and long side  113 , 115  of the covering material  123  in the top section. The total length of the first lift cord  117  within the top section  103  is equal to the total length of the second lift cord  119  within the top section  103  when the covering material  123  is extended. 
     Preferably a spring  127  is also provided in the head rail  105 , attached to a support wire  129 . The spring  127  and support wire  129  prevent the right end of the middle rail  107  from pivoting downwardly below the left end of the middle rail. 
     When the cord member  125  is pulled downwardly, the cord collector  121  pulls the first and second pull cords  117 ,  119  outwardly of the blind  101 . As shown in  FIG. 3 , this initially causes: the first pull cord  117  to pull up the wire loop  129  attached to the bottom rail  111  and thereby the right end of the bottom rail and the pull cord parts  119 A,  119 B to pull up the left end and middle of the bottom rail  111  until the middle and bottom rails are vertically adjacent to one another. When the cord member  125  is pulled further downwardly, this causes the first pull cord  117  to pull up the middle rail  107  at its first and second guides and to pull up further the wire loop  129  and the bottom rail  111  while the second pull cord parts pull up further the left end and middle of the bottom rail, so that both the middle and bottom rails pivot about the pivot center of the middle rail. 
       FIG. 4  shows another embodiment of a blind  201  which is similar to the blind  1  of  FIG. 1  and for which corresponding reference numerals (greater by  200 ) are used below for describing the parts or corresponding parts. 
     Blind  201  includes a fixed inclined head rail  205  and a raisable horizontally extending bottom rail  211 . Between the head rail  205  and bottom rail  211  is a middle rail  207  that is pivotable with respect to the head rail  205  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  205 ,  207 ,  211  are a pair of lift cords  217 ,  219  which extend, between the rails, through perforations in a covering member  223 , attached to the top, middle and bottom rails. 
     The head rail  205  and middle rail  207  and the triangular top portion of the covering member  223 , attached to them, form a top section  203  of the blind  201  with an unattached short apex  213  about the pivot center of the top section and an opposite, unattached, long side  215  when the covering material extended. The middle rail  207  and bottom rail  211  and the rectangular bottom portion of the covering member  223 , attached to them, form a bottom section  209  of the blind  201 . 
     The blind  201  has a vertically movable cord collector  221  with a depending cord member  225  outside of the blind. The two lift cords  217 ,  219  are attached to the cord collector  221  and are routed through, and deflected by, the head, middle and bottom rails  205 ,  207 ,  211  as shown in  FIG. 4 . 
     Both ends of both lift cords  217 ,  219  are attached to the collector  221 . The cord member  225  can be used to raise and lower the collector  221  to raise and lower the middle and bottom rails  207 ,  211  and thereby retract and extend the covering member  223  as described below. 
     The routing of the first lift cord  217  in the blind  201  in accordance with this invention is as follows (with reference to  FIG. 4 ). The first lift cord  217  extends rightwardly through the head rail  205 , away from the collector  221 , to a first guide in the bottom of the head rail adjacent its left end. The first lift cord  217  extends downwardly from the first guide in the head rail to a first guide in the top of the middle rail  207  that is adjacent—i.e. just to the right of—the apex  213  of the covering material  223  in the top section  203  and adjacent the left end of the middle rail. The first lift cord  217  then extends downwardly through the first guide in the middle rail to a first guide in the bottom rail  211 . The first lift cord  217  then extends rightwardly through the bottom guide  211  to a second guide in the bottom rail  211  generally midway between opposite ends of the bottom rail  211 . It then extends upwardly to a second guide in the middle rail  207  and then extends rightwardly through the middle rail  207  to a third guide in the middle rail  207 , adjacent its right end. The first lift cord  217  then extends upwardly from the third guide in the middle rail adjacent to—i.e. just to the left of—the long side  215  of the covering material  223  in the top section  203 , to a second guide in the head rail  205 , adjacent its right end. The lift cord then extends leftwardly through the head rail  205 , from its second guide, back to the collector  221 . 
     The second lift cord extends rightwardly through the head rail  205 , away from its left end and the collector  221 , and, at a third guide in the bottom rail  205 —midway between the first and second guides in the headrail  205 —it extends downwardly to a fourth guide in the top of the middle rail  207 . The fourth guide in the bottom of the middle rail  207  can be adjacent to—i.e. just to the right of—the second guide in the top of the middle rail  207  as shown schematically in  FIG. 4 , but, preferably, the second and fourth guides in the middle rail are coaxial. The second lift cord then extends downwardly through the fourth guide in the middle rail  207  to a third guide in the bottom rail  211 , midway between the ends of the bottom rail  211 . The third guide in the bottom rail  211  can be adjacent to—i.e. just to the right of—the second guide in the bottom rail  211  as shown schematically in  FIG. 4 , but, preferably the second and third guides in the middle rail are coaxial. The second lift cord then extends rightwardly through the bottom rail  211  to a fourth guide in the bottom rail  211  at the right end of the bottom rail  211 . The second lift cord  219  then extends upwardly from the fourth guide to a fifth guide in the middle  207  and then extends leftwardly through the middle  207  to a sixth guide. The sixth guide through the middle  207  can be adjacent—i.e. just to the right of—the fourth guide in the middle rail as shown schematically in  FIG. 4 , but, preferably, the fourth and fifth guides in the middle rail are coaxial. The second lift cord  219  then extends upwardly from the sixth guide in the middle rail to a fourth guide in the head rail  205  midway between the first and second guides. The fourth guide in the head rail  205  can be adjacent—i.e. just to the right of—the third guide in the head rail as shown schematically in  FIG. 4 , but, preferably, the third and fourth guides in the head rail are coaxial. The second lift cord  219  then extends leftwardly through the head rail, from its fourth guide, back to the collector  221 . 
     The total length of the first lift cord  217  within the top section  203  is equal to the total length of the second lift cord  219  within the top section  213  when the covering material  223  is extended. 
     Preferably a spring  227  is also provided in the head rail  205 , attached to a support wire  229 . The spring  227  and support wire  229  prevent the right end of the middle rail  207  from pivoting downwardly below the left end of the middle  207 . 
     When the cord member  225  is pulled downwardly, the cord collector  221  pulls the first and second pull cords  217 ,  219  outwardly of the blind  201 . This initially causes the first pull cord to pull up the left end of the bottom rail  211  and the second pull cord to pull up the right end of the bottom rail  211  until the middle and bottom rails are vertically adjacent to one another. When the cord member  225  is pulled further downwardly, this causes the first pull cord  217  to pull up the middle rail  207  at its first and third guides, while the second pull cord pulls up the middle section of the middle rail. 
       FIG. 5  shows another embodiment of a blind  301  which is similar to the blind  1  of  FIG. 1  and for which corresponding reference numerals (greater by  300 ) are used below for describing the parts or corresponding parts. 
     Blind  301  includes a fixed inclined head rail  305  and a raisable horizontally extending bottom rail  311 . Between the head rail  305  and bottom rail  311  is a middle rail  307  that is pivotable with respect to the head rail  305  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  305 ,  307 ,  311  are a pair of lift cords  317 ,  319  which extend, between the rails, through perforations in a covering member  323 , attached to the top, middle and bottom rails. 
     The head rail  305  and middle rail  307  and the triangular top portion of the covering member  323 , attached to them, form a top section  303  of the blind  301  with an unattached short apex  313  about the pivot center of the top section and an opposite, unattached, long side  315  when the covering material extended. The middle rail  307  and bottom rail  311  and the rectangular bottom portion of the covering member  323 , attached to them, form a bottom section  309  of the blind  301 . 
     The blind  301  has a vertically movable cord collector  321  with a depending cord member  325  outside of the blind. The two lift cords  317 ,  319  are attached to the cord collector  321  and are routed through, and deflected by, the head, middle and bottom rails  305 ,  307 ,  311  as shown in  FIG. 5 . 
     Both ends of both of the lift cords  317 ,  319  are attached to the collector  321 . The cord member  325  can be used to raise and lower the collector  321  to raise and lower the middle and bottom rails  307 ,  311  and thereby retract and extend the covering member  323  as described below. 
     The routing of the first lift cord  317  in the blind  301  in accordance with this invention is as follows (with reference to  FIG. 5 ). The first lift cord  317  extends to the right through the headrail  305  away from the collector  321  to a first guide in the bottom of the headrail, adjacent its left end. The first lift cord  317  extends downwardly from the first guide in the head rail to a first guide in the top of the middle rail  307  that is adjacent—i.e. just to the right of—the apex  313  of the covering material  323  in the top section  303  and adjacent the left end of the middle rail. The first lift cord  317  then extends rightwardly through the middle  307  to a second guide in the bottom of the middle rail, partway across, for instance one third, and then extends downwardly to a first guide in the top of the bottom rail  311 , again partway along, for instance a third, the length of the bottom rail  311 . The first lift cord  317  then extends along the bottom rail  311  to a second guide in the bottom rail, adjacent its right end. The first lift cord  317  then extends upwardly from the second guide in the bottom rail up to a third guide in the middle rail  307 , adjacent its right end. From the third guide in the middle rail  307 , the first lift cord  317  then extends upwardly to a second guide in the head rail  305  towards its right end. The first lift cord then extends leftwardly through the head rail, from its second guide, back to the collector  321 . 
     The second lift cord  319  extends rightwardly through the head rail  305 , away from the collector  321 , to a third guide in the bottom of the head rail  305 , partway, for instance a third, along the head rail  305 . The second lift cord  319  then extends downwardly to a fourth guide in the top of the middle rail  307  again partway, for instance a third, along the middle rail  307 . The fourth guide of the middle rail  307  may be adjacent to the second guide of the middle  307 , but, preferably coaxially above the second guide as illustrated schematically in  FIG. 5 . The second lift cord  319  then extends leftwardly through the middle  307  to a fifth guide in the bottom of the middle rail adjacent its left end. The fifth guide in the middle rail  307  may be adjacent to the first guide in the middle rail, but, preferably, is coaxially below the first guide as illustrated schematically in  FIG. 5 . The second lift cord  319  then extends downwardly from the fifth guide in the middle rail  307  to a third guide in the bottom rail  311  immediately adjacent to the left end of the bottom rail  311 . The second lift cord  319  then extends rightwardly through the bottom rail  311  to a fourth guide partway, for instance two thirds, along the bottom rail  311 . The second lift cord  319  then extends upwardly from the fourth guide in the bottom rail  311  to a sixth guide in the middle rail  307  partway, for instance two thirds, along the middle rail  307  from the left end and the apex  313 . The second lift cord  319  then extends upwardly from the sixth guide in the middle rail to a fourth guide in the bottom of the headrail  305  partway, for instance two thirds, along its length from the left end. The second lift cord then extends leftwardly through the headrail, from its fourth guide, back to the collector  321 . 
     The total length of the first lift cord  319  within the top section  303  is equal to the total length of the second lift cord  319  within the top section  303  when the covering material  323  is extended. 
     Preferably, a spring  327  is also provided in the headrail  305 , attached to a support wire  329 . The spring  327  and support wire  329  prevent the right end of the middle rail  307  from pivoting downwardly below the left end of the middle rail  307 . 
     When the cord member  325  is pulled downwardly, the cord collector  321  pulls the first and second pull cords  317 ,  319  outwardly of the blind  301 . This initially causes the first pull cord  317  to pull up the bottom rail  311  towards the right hand end and the second pull cord  319  to pull up the left hand end until the middle and bottom rails are vertically adjacent to one another. When the cord member  325  is pulled further downwardly, this causes the first pull cord to pull up the middle rail  307  at its third guide and to pull up further the bottom rail  311  while the second cord  319  pulls up the middle portion of the middle rail  307 . 
       FIG. 6  shows another embodiment of a blind  401  which is similar to the blind  1  of  FIG. 1  and for which corresponding reference numerals (greater by  400 ) are used below for describing the parts or corresponding parts. 
     Blind  401  includes a fixed inclined head rail  405  and a raisable horizontally extending bottom rail  411 . Between the head rail  405  and bottom rail  411  is a middle rail  407  that is pivotable with respect to the head rail  405  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  405 ,  407 ,  411  are a pair of lift cords  417 ,  419  which extend, between the rails, through perforations in a covering member  423 , attached to the top, middle and bottom rails. 
     The head rail  405  and middle rail  407  and the triangular top portion of the covering member  423 , attached to them, form a top section  403  of the blind  401  with an unattached short apex  413  about the pivot center of the top section and an opposite, unattached, long side  415  when the covering material is extended. The middle rail  407  and bottom rail  411  and the rectangular bottom portion of the covering member  423 , attached to them, form a bottom section  409  of the blind  401 . 
     The blind  401  has a vertically movable cord collector  421  with a depending cord member  425  outside of the blind. The two lift cords  417 ,  419  are attached to the cord collector  421  and are routed through, and deflected by, the head, middle and bottom rails  405 ,  407 ,  411  as shown in  FIG. 6 . 
     Both ends of both lift cords  417 ,  419  are attached to the collector  421 . The cord member  425  can be used to raise and lower the collector  421  to raise and lower the middle and bottom rails  407 ,  411  and thereby retract and extend the covering member  423  as described below. 
     The routing of the first lift cord  417  in the blind  401  in accordance with this invention is as follows (with reference to  FIG. 6 ). The first lift cord  417  extends rightwardly through the head rail  405  away from the collector  421  to a first guide in the head rail, adjacent its left end. The first lift cord  417  extends downwardly from the first guide in the head rail to a first guide in the top of the middle rail  407  that is adjacent—i.e. just to the right of—the apex  413  of the covering material  423  in the top section  403  and adjacent the left end of the middle rail. The first lift cord  417  then extends rightwardly through the middle rail  407  to a second guide in the bottom of the middle rail generally at the center of middle rail  407 . It then extends downwardly to a first guide of the bottom rail  411  positioned generally half way along the bottom rail  411 . The first lift cord  417  then extends along the bottom rail  411  to a second guide at the right end of the bottom rail  411  and, from the second guide, extends upwardly to a third guide of the middle rail  407 . At the right end of the middle rail  407 . The first lift cord  417  then extends upwardly from the third guide in the middle rail adjacent to—i.e. just to the left of—the long side  415  of the covering material  423  in the top section  403 , to a second guide in the bottom of the head rail  405  adjacent its right end. The first lift cord then extends leftwardly through the head rail, from its second guide, back to the collector  421 . 
     The second lift cord  419  extends rightwardly through the head rail  405 , away from the collector  421 , to a third guide in the bottom of the head rail  405  at a position generally half way along the head rail  405 . The second lift cord  419  extends downwardly from the third guide in the head rail to a fourth guide in the top of the middle rail  407 . The fourth guide of the middle rail  407  may be adjacent to the second guide of the middle rail  407 , but, preferably, the fourth guide is position coaxially above the second guide as illustrated schematically in  FIG. 6 . The second lift cord  417  then extends leftwardly through the middle rail  407  to a fifth guide in the bottom of the middle rail  407  and adjacent its left end. The fifth guide may be adjacent the first guide, but, preferably, is positioned coaxially below the first guide as illustrated schematically in  FIG. 6 . The second lift cord then extends downwardly from the fifth guide of the middle rail  407  to a third guide of the bottom rail  411  at the left end of the bottom rail  411 . The second lift cord  417  then extends rightwardly through the bottom rail  411  to a fourth guide in the bottom rail  411 . The fourth guide through the bottom rail  411  can be adjacent—i.e. just to the right of—the first guide in the bottom rail  411  as shown schematically in  FIG. 6 , but, preferably, the first and fourth guides in the bottom rail are coaxial. The second lift cord  419  then extends upwardly from the fourth guide to a sixth guide in the middle rail  407 . The sixth guide through the middle rail  407  can be adjacent—i.e. just to the right of—the second and fourth guides in the middle rail as shown schematically in  FIG. 6 , but, preferably, the sixth guide is coaxial with the second and fourth guides. From the sixth guide in the middle rail  407 , the second lift cord  417  continues upwardly to a fourth guide in the head rail  405 . The fourth guide through the head rail  405  can be adjacent—i.e. just to the right of—the third guide in the head rail as shown schematically in  FIG. 6 , but, preferably, the third and fourth guides in the head rail are coaxial. The second lift cord then extends leftwardly through the head rail  405 , from its fourth guide, back to the collector  421 . 
     The total length of the first lift cord  417  within the top section  403  is equal to the total length of the second lift cord  419  within the top section  403  when the covering material  423  is extended. 
     Preferably, a spring  427  is also provided in the head rail  405 , attached to a support wire  429 . The spring  427  and support wire  429  prevent the right end of the middle rail  407  from pivoting downwardly below the left end of the middle rail. 
     When the cord member  425  is pulled downwardly, the cord collector  421  pulls the first and second pull cords  417 ,  419  outwardly of the blind  401 . This initially causes the first pull cord  417  to pull up the right-hand section of the bottom rail  411  and the second pull cord  419  to pull up the left-hand section of the bottom rail  411 . When the cord member  425  is pulled further downwardly, this causes the first pull cord  417  to pull up the middle rail  407  at its first and third guides and to pull up further the bottom rail  411  while the second pull cord pulls up further the left end and middle of the bottom rail  411  so that both the middle and bottom rails pivot about the pivot center of the middle rail. 
       FIG. 7  shows another embodiment of a blind  501  which is similar to the blind  1  of  FIG. 1  and for which corresponding reference numerals (greater by  500 ) are used below for describing the parts or corresponding parts. 
     Blind  501  includes a fixed inclined head rail  505  and a raisable horizontally extending bottom rail  511 . Between the head rail  505  and bottom rail  511  is a middle rail  507  that is pivotable with respect to the head rail  505  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  505 ,  507 ,  511  are a pair of lift cords  517 ,  519  which extend, between the rails, through perforations in a covering member  523 , attached to the top, middle and bottom rails. 
     The head rail  505  and middle rail  507  and the triangular top portion of the covering member  523 , attached to them, form a top section  503  of the blind  501  with an unattached short apex  513  about the pivot center of the top section and an opposite, unattached, long side  515  when the covering material is extended. The middle rail  507  and bottom rail  511  and the rectangular bottom portion of the covering member  523 , attached to them, form a bottom section  509  of the blind  501 . 
     The blind  501  has a vertically movable cord collector  521  with a depending cord member  525  outside of the blind. The two lift cords  517 ,  519  are attached to the cord collector  521  and are routed through, and deflected by, the head, middle and bottom rails  505 ,  507 ,  511  as shown in  FIG. 7 . 
     The arrangement of the first and second lift cords  517 ,  519  within the blind itself is identical to the embodiment of  FIG. 6 . However, the collector  521  and cord member  525  are positioned on the right side of the blind  501 , i.e. just to the right of the long side  515  of the covering material  523  in the top section  503 . The first and second lift cords  517 ,  519  therefore run in an opposite direction (in terms of left and right) from the collector  521 . 
     It will be appreciated that the cord collector and the cord member  525  can be repositioned in this way for any embodiment. 
       FIG. 8  shows another embodiment of a blind  601  which is similar to the blind  1  of  FIG. 1  and for which corresponding reference numerals (greater by  600 ) are used below for describing the same parts of corresponding parts. The blind differs most significantly from the blind  1  of  FIG. 1  by having three, rather than two lift cords. 
     The blind  601  includes a fixed inclined head rail  605  and a raisable horizontally extending bottom rail  611 . Between the head rail  605  and bottom rail  611  is a middle rail  607  that is pivotable with respect to the head rail  605  about a pivot center that is adjacent to the lowermost left end of the head rail. Attached to the top, middle and bottom rails  605 ,  607 ,  611  are three lift cords  617 ,  618  and  619  which extend between the rails through perforations in a covering member  623  attached to the top, middle and bottom rails. 
     The head rail  605  and middle rail  607  and the triangular top portion of the covering member  623 , attached to them, form a top section  603  of the blind  601  with an unattached short apex  613  about the pivot center of the top section and an opposite, unattached long side  615  when the covering material is extended. The middle rail  607  and bottom rail  611  and the rectangular bottom portion of the covering member  623 , attached to them, form a bottom section  609  of the blind  601 . 
     The blind  601  has a vertically movable cord collector  621  with a depending cord member  625  outside of the blind. Three lift cords  617 ,  618 ,  619  are attached to the cord collector  621  and are routed through, and deflected by, the head, middle and bottom rails  605 ,  607 ,  611  as shown in  FIG. 8 . Both ends of all three lift cords  617 ,  618 ,  619  are attached to the collector  621 . The cord member  625  can be used to raise and lower the collector  621  to raise and lower the middle and bottom rails  607 ,  611  and thereby retract and extend the covering member  623  as described below. 
     The embodiment of  FIG. 8  is identical to that of  FIG. 6  other than the addition of the third lift cord  618 . The routing of the first lift cord  617  and second lift cord  619  is the same as was described for the first lift cord  417  and second lift cord  419  of  FIG. 6 . Hence, this description will not be repeated here. 
     The routing of the third lift cord  618  in the blind  608  in accordance with this invention is as follows (with reference to  FIG. 8 ). The third lift cord  618  extends to the right through the head rail  605 , away from the collector  621 , to a fifth guide in the bottom of the head rail someway, for instance a quarter of the way, from the left end of the head rail  605 . The third lift cord  618  extends downwardly from the fifth guide in the head rail to a seventh guide in the top of the middle rail  607  that similarly is someway, for instance a quarter of the way, from the left end of the middle rail  607  and, hence, the apex  613  of the covering material  623 . The third lift cord  618  then extends downwardly from the seventh guide of the middle rail  607  to a fifth guide of the bottom rail  611 . Similarly, the fifth guide of the bottom rail  611  is positioned someway, for instance a quarter of the way, from the left end of the bottom rail  611 . The third lift cord  618  then extends rightwardly through the bottom rail  611  to a sixth guide in the bottom rail  611  which is someway, for instance three quarters of the way, from the left end of the bottom rail  611 . The third lift cord  618  then extends upwardly to an eighth guide in the middle rail  607  again someway, for instance three quarters of the way, from the left end of the middle rail  607 . The third lift cord  618  extends through the eighth guide of the middle rail  607  and then upwardly to a sixth guide of the head rail  605  which, again, is someway, for instance three quarters of the way, from the left end of the head rail  605 . The third lift cord then extends leftwardly through the head rail, from its fifth guide, back to the collector  621 . 
     The total length of the third lift cord  618  within the top section  603  is equal to the total length of the first lift cord  617  within the top section  103  and also to the total length of the second lift cord  619  within the top section  603  when the covering material  623  is extended. The positioning of the fifth and sixth guides in the head rail  605  and the seventh and eighth guides in the middle rail  607  and the fifth and sixth guides in the bottom rail  611  can be varied in any way, provided that this condition is met. 
     When the cord member  625  is pulled downwardly, the cord collector  621  pulls the first, second and third pull cords  617 ,  619 ,  618  outwardly of the blind. The first and second pull cords  617  and  619  operate as described for  FIG. 6 . The third pull cord  619  initially pulls up the bottom rail  611  at mid-sections along its length and then causes the middle and bottom rails to pivot about the pivot center of the middle rail. 
     It will be appreciated that third or further cords could be added to any of the embodiments. Third or further cords help provide a more evenly distributed lifting and rotating force on the bottom and middle rails. 
     This invention is, of course, not limited to the above-described embodiments which may be modified without departing from the scope of the invention or sacrificing all of its advantages. In this regard, the terms in the foregoing description and the following claims, such as “top”, “middle”, “bottom”, “left”, “right”, “vertical” and “horizontal”, have been used only as relative terms to describe the relationships of the various elements of the blind of the invention. For example, the blind covering material  23 , 123  need not be a pleated blind material but can be any flexible material sheet member that is foldable, pleatable or rollable. The blind covering material can also be formed as a collapsible slatted blind in which the vanes or slats may be pivotally adjustable for additional light regulation. Likewise, the movable middle rail  7 , 107  and bottom rail  11 , 111  can be either directly or indirectly attached to the covering material  23 , 123  in the top section  3 , 103  and bottom section  9 ,  109  of the blind  1 , 101  in order to extend and retract the top and bottom sections.

Summary:
A retractable blind assembly including a top section ( 3,103 ) with a vertically-extending blind covering material ( 23,123 ) extending between a fixed inclined head rail ( 5,105 ) and a middle rail ( 7,107 ) that is pivotable with respect to the head rail ( 5,105 ) about a pivot center that is adjacent to a lowermost end of the head rail, the head rail extending upwardly at an acute angle, the middle rail ( 7,107 ) being pivotable between a lower position, in which the middle rail extends horizontally, when the covering material is extended and an upper position, in which the middle rail extends upwardly at an acute angle and is adjacent the head rail, when the covering material is retracted, the covering material in the top section ( 3,103 ) having a generally triangular shape with an unattached short apex ( 13,113 ) about the pivot center and an opposite, unattached, long side ( 15,115 ) when the covering material is extended, a bottom section ( 9,109 ) with the covering material extending between the middle rail ( 7,107 ) and a horizontally-extending bottom rail ( 11,111 ), the bottom rail being movable vertically between the bottom of the blind when the covering material is extended and an upper position, adjacent the middle rail, when the covering material is retracted, at least first and second lift cords ( 17, 19, 117, 119 ) for extending and retracting the covering material, the lift cords being connected outside the blind to a cord connector ( 21,121 ), wherein the first lift cord ( 17,117 ) is routed through the top section ( 3,103 ) adjacent its apex and long side ( 13,15,113,115 ) and the second lift cord ( 19,119 ) is routed such that it passes through the top section between its apex and long side, and wherein when the covering material ( 23,123 ) is extended, the total length of the first lift cord ( 17,117 ) within the top section ( 3,103 ) is equal to the total length of the second lift cord ( 19,119 ) within the top section.