Patent Publication Number: US-8113264-B2

Title: Tensioned roller shade system having a conical, grooved spool

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of commonly-assigned, co-pending U.S. patent application Ser. No. 12/061,802, filed Apr. 3, 2008, entitled SELF-CONTAINED TENSIONED ROLLER SHADE SYSTEM, which claims priority from commonly-assigned U.S. Provisional Application Ser. No. 61/035,911, filed Mar. 12, 2008, entitled SELF-CONTAINED TENSIONED ROLLER SHADE SYSTEM. The entire disclosures of both applications are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a motorized window treatment, and more particularly, to a self-contained tensioned roller shade system that allows for easy installation into a window opening oriented, for example, in a non-vertical plane, such as a skylight. 
     2. Description of the Related Art 
     Typical motorized window treatments, such as, for example, roller shades, draperies, roman shades, and venetian blinds, are mounted in front of vertically-oriented windows to prevent sunlight from entering a space and to provide privacy. A motorized roller shade includes a flexible shade fabric wound onto an elongated roller tube. The flexible shade fabric typically includes a weighted hembar at a lower end of the shade fabric, such that the shade fabric is pulled down by gravity and simply hangs in front of the window. Motorized roller shades include a drive system engaging the roller tube to provide for tube rotation, such that the lower end of the shade fabric can be raised and lowered by rotating the roller tube. 
     While most windows are oriented vertically, skylight windows are typically mounted in a non-vertical plane. Some prior art motorized roller shade systems have been installed in skylight windows. These prior art skylight shade systems typically comprise tensioning systems, in which an amount of tension is provided to the shade fabric to minimize the sagging in the shade fabric. One prior art tensioning system includes two roller tubes where each roller tube is rotated by a separate motor. Specifically, one of the roller tubes is coupled to a first end of the shade fabric and windingly receives the shade fabric. The second roller tube winds up cables that are attached to a second end of the shade fabric, such that the shade fabric may be pulled by the cables as the second roller tube rotates. Since the motor in each of the roller tubes is stressed by the tension of the shade fabric, the motors must be larger (and thus noisier) than typical motors. Further, separately controlling each of the motors of this “dual-motor” shade system (e.g., to pull the shade fabric, to stop movement of the shade fabric, to apply the appropriate tension to the shade fabric) is rather complex and unreliable. 
     Another prior art tensioning system also includes two roller tubes with a first roller tube rotated by a motor (at a first end of the shade fabric) and a second roller tube that is spring-biased to provide tension in the shade fabric. Once again, the motor is stressed by the tension of the shade fabric and thus is larger and noisier than a typical motor. Further, the spring of the spring-biased roller tube limits the size (i.e., the length) of the shade fabric that may be tensioned by the roller shade system. An example of such a tensioning system is described in greater detail in U.S. Pat. No. 5,467,266, issued Nov. 14, 1995, entitled MOTOR-OPERATED WINDOW COVER. Both of these prior art tensioning systems require all of the system components to be individually installed in the opening, which can be rather difficult for a skylight window. 
     There is a need for a skylight shade system that minimizes the stress on the motor due to the tension in the shade fabric. Further, there is also a need for a skylight shade system that is easy to install and is scalable to allow for multiple sizes of roller tubes and shade fabrics. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the present invention, a tensioned roller shade system comprises first and second space-apart parallel side channels, a roller tube, a first conical, grooved spool, a shade fabric, a hembar, a first pulley, and a first tensioning cord. Each of the first and second side channels has a proximal end and a distal end. The roller tube is rotatably mounted between the proximal ends of the first and second side channels and is adapted to rotate about a tube axis. The first spool has a first spool end adjacent the first tube end, a second spool end, and a single groove that wraps around the spool from the first spool end to the second spool end. The spool is adapted to rotate about the tube axis. The shade fabric has a first fabric end connected to the roller tube (such that the shade fabric is windingly received around the roller tube) and a second fabric end opposite the first fabric end. The hembar is connected to the shade fabric at the second fabric end, and comprises a first hembar end having first hembar wheels and a second hembar end having second hembar wheels. The first hembar wheels are received by a first hembar slot of the first side channel and the second hembar wheels are received by a second hembar slot of the second side channel. The first pulley is located in the first side channel adjacent the distal end of the first side channel. The first tensioning cord is operatively coupled between the first spool and the second fabric end, and is coupled to the first spool for winding receipt about the spool. The tensioning cord is windingly received around the first pulley, such that the tensioning cord is adapted to bias the hembar toward the distal ends of the side channels, and the hembar of the shade fabric is adapted to move between the distal ends and the proximal ends of the side channels as the roller tube is rotated. The first and second side channels each include respective flanges and interior walls. The first and second hembar slots are formed between the flange and the interior wall of each side channel, and each define sidewalls between the respective flange and the respective interior wall. Each sidewall has a non-planar surface to allow for rolling contact with the sides of the respective wheels of the hembar. 
     According to another embodiment of the present invention, a self-contained tensioned roller shade system is adapted to be mounted in an opening having first and second opposite sides, and third and fourth opposite sides. The self-contained tensioned roller shade system comprises a free-standing frame, a roller tube, first and second conical, grooved spools, a shade fabric, a hembar, first and second pulleys, first and second tensioning cord portions, and a first spring. The frame has first and second opposite sides defining respective first and second side channels adapted to be mounted along the first and second opposite sides of the opening, respectively, and third and fourth opposite sides defining respective first and second frame ends adapted to be mounted along the third and fourth opposite sides of the opening, respectively. The roller tube is rotatably mounted between the first and second side channels of the frame adjacent the first frame end, and is adapted to rotate about a tube axis. The first and second spools are connected to respective first and second tube ends of the roller tube and are adapted to rotate about the tube axis as the roller tube rotates. Each spool comprises a first spool end having a first diameter, a second spool end having a second diameter larger than the first diameter, and a single groove wrapping around the spool from the first spool end to the second spool end. The first spool ends of the first and second spools are located adjacent the first and second tube ends, respectively. The shade fabric has a first fabric end connected to the roller tube, such that the shade fabric is windingly received around the roller tube. The hembar is connected to the shade fabric at a second fabric end opposite the first fabric end of the shade fabric. The hembar has a first hembar end received by the first side channel and a second hembar end received by the second side channel. The first and second pulleys are operatively coupled to the frame adjacent the second frame end and are located in the first and second side channels, respectively. The first tensioning cord portion operatively coupled between the first spool at the first tube end of the roller tube and the first hembar end of the hembar, and is coupled to the first spool for winding receipt about the first spool. The second tensioning cord portion is operatively coupled between the second spool at the second tube end of the roller tube and the second hembar end of the hembar, and is coupled to the second spool for winding receipt about the second spool. The first and second tensioning cord portions are windingly received around the first and second pulleys, respectively. The first spring is coupled to the frame, is located within the first side channel, and is operatively coupled to the first tensioning cord portion, such that the hembar is biased towards the second frame end, the shade fabric and the tensioning cord apply forces on the first and second frame ends to pull the frame ends towards each other, and the hembar is adapted to move between the first and second frame ends as the roller tube is rotated. The free-standing frame contains the forces applied on the first and second frame ends by the shade fabric and the tensioning cord to minimize the forces applied by the frame on the opening in which the roller shade system is mounted. 
     In addition, a method of installing a tensioned roller shade system in an opening is described herein. The method comprises the steps of: (1) providing a free-standing frame having first and second side channels, each of the side channels having a proximal end and a distal end; (2) mounting a roller tube between the first and second side channels adjacent the proximal ends of the first and second side channels, such that the roller tube is operable to rotate; and (3) connecting conical, grooved spools at opposite tube ends of the roller tube such that the spools are adapted to rotate about the tube axis as the roller tube rotates, where each spool comprises a first spool end having a first diameter, a second spool end having a second diameter larger than the first diameter, and a single groove wrapping around the spool from the first spool end to the second spool end, and the first spool ends of the first and second spools are located adjacent the first and second tube ends, respectively; (4) connecting a first fabric end of a shade fabric to the roller tube, such that the shade fabric is windingly received around the roller tube; (5) coupling opposite ends of a tensioning cord to the first and second spools for winding receipt about the spools; (6) coupling the tensioning cord to a pulley operatively coupled to the first side channel adjacent the distal end of the first side channel, such that the tensioning cord is windingly received around the pulley; (7) operatively coupling the tensioning cord to a second fabric end opposite the first fabric end of the shade fabric; (8) connecting a spring between the pulley and the frame; (9) biasing the second fabric end towards the distal ends of the first and second side channels, such that the shade fabric and the tensioning cord apply forces on the frame; (10) adjusting the amount of force applied to the tensioning cord by the spring; and (11) subsequently installing the frame into the opening, such that the free-standing frame contains the forces applied by the shade fabric and the tensioning cord to minimize the forces applied by the frame on the opening in which the roller shade system is mounted, and the second fabric end of the shade fabric is adapted to move between the proximal and distal ends of the first and second side channels as the roller tube is rotated. 
     Other features and advantages of the present invention will become apparent from the following description of the invention that refers to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view a self-contained tensioned roller shade system for mounting in an opening, such as a window or a skylight, according to a first embodiment of the present invention; 
         FIG. 2  is a front view of the roller shade system of  FIG. 1 ; 
         FIG. 3  is a left-side cross-sectional view of the roller shade system of  FIG. 1 ; 
         FIG. 3   a  is a simplified left-side schematic view of the roller shade system of  FIG. 1 ; 
         FIG. 4  is an enlarged detail of the left-side cross-sectional view of  FIG. 3  showing an end of a roller tube of the roller shade system in greater detail; 
         FIG. 5  is an enlarged detail of the left-side cross-sectional view of  FIG. 3  showing pulleys of the roller shade system in greater detail; 
         FIG. 6  is a partial perspective view of the roller shade system showing the pulleys of  FIG. 5  in greater detail; 
         FIG. 7  is a front cross-sectional view of the roller shade system of  FIG. 1 ; 
         FIG. 8  is an enlarged detail of the front cross-sectional view of  FIG. 7  showing a first side channel and a first hembar end of a hembar of the roller shade system in greater detail; 
         FIG. 9  is a bottom cross-sectional view of the roller shade system of  FIG. 1 ; 
         FIG. 10  is an enlarged detail of the bottom cross-sectional view of  FIG. 9  showing the first side channel in greater detail; 
         FIG. 11  is a perspective view of the first hembar end of the hembar of the roller shade system of  FIG. 1 ; 
         FIG. 12  is an enlarged detail of the left-side cross-sectional view of  FIG. 3  showing a tensioning screw of the roller shade system in greater detail; 
         FIG. 13  is a left-side cross-sectional view of a roller shade system according to a second embodiment of the present invention; 
         FIG. 13   a  is a simplified left-side schematic view of the roller shade system of  FIG. 13 ; 
         FIG. 14  is a left-side cross-sectional view of a roller shade system according to a third embodiment of the present invention; 
         FIG. 14   a  is a simplified left-side schematic view of the roller shade system of  FIG. 14 ; 
         FIG. 15  is a simplified front schematic view of a roller shade system according to a fourth embodiment of the present invention; 
         FIG. 16  is a simplified front schematic view of a roller shade system according to a fifth embodiment of the present invention; 
         FIG. 17  is an enlarged front cross-sectional view of a roller shade system according to a sixth embodiment of the present invention showing the first tube end of the roller tube in greater detail; 
         FIG. 18  is a perspective view of a conical, grooved spool of the roller shade system of  FIG. 17 ; and 
         FIG. 19  is an enlarged front cross-sectional view of the first tube end of the roller tube and the first spool of the roller shade system of  FIG. 17  taken through the center of the roller tube. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention, there is shown in the drawings an embodiment that is presently preferred, in which like numerals represent similar parts throughout the several views of the drawings, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed. 
       FIG. 1  is a perspective view and  FIG. 2  is a front view of a self-contained tensioned roller shade system  100  adapted to be easily mounted in an opening (such as, a window) that is oriented in a vertical plane or in a non-vertical plane (such as, a skylight that may be mounted, for example, horizontally). Note that if the roller shade system  100  is mounted in a skylight, the perspective view of  FIG. 1  and the front view of  FIG. 2 , would be viewed from the outside of the skylight window. 
     The roller shade system  100  comprises a free-standing frame  110 , which allows the roller shade system  100  to be assembled in the frame before the roller shade system is installed in the opening, therefore providing for an easy installation process. The frame  110  has first and second spaced-apart, opposite sides defining respective first and second side channels  112 ,  114 , and third and fourth spaced-apart, opposite sides defining respective first and second frame ends  116 ,  118 . The first and second side channels  112 ,  114  each have proximal ends (adjacent the first frame end  116 ) and distal ends (adjacent the second frame end  118 ). The roller shade system  100  further comprises a shade fabric  120  coupled between a roller tube  122  and a hembar  124 . The roller tube  122  is rotatably mounted between the proximal ends of the first and second side channels  112 ,  114  adjacent the first frame end  116  and is located below the shade fabric  120  (as shown in  FIGS. 1 and 2 ). The roller tube  122  is adapted to rotate about a tube axis. 
     A first fabric end of the shade fabric  120  is connected to the roller tube  122 , such that the shade fabric is windingly received around the roller tube. The hembar  124  is connected to a second fabric end of the shade fabric  120  and has first and second hembar ends that are coupled to respective hembar slots  152 A,  152 B ( FIG. 3 ) in the respective side channels  112 ,  114 . The roller shade system  100  comprises a tensioning system (as will be described in greater detail below), which is used to translate the hembar  124  along the hembar slots  152 A,  152 B between the first frame end  116  (i.e., the roller shade system is open) and the second frame end  118  (i.e., the roller shade system is closed) as the roller tube  122  is rotated. 
     The first side channel  112  comprises a first flange  126 A and a second flange  128 A ( FIG. 6 ), while the second side channel  114  comprises a first flange  126 B and a second flange  128 B. The flanges  126 A,  126 B,  128 A,  128 B provide additional structure for the frame  110 , while also hiding the operational components of the tensioning system of the roller shade system  100  from view. The first and second flanges  126 A,  126 B,  128 A,  128 B of each side channel  112 ,  114  are spaced apart appropriately, such that the roller tube  122  may be easily unmounted and removed from the frame  110 . For example, the first and second flanges  126 A,  126 B,  128 A,  128 B may be spaced apart at a distance greater than the diameter of the roller tube  122 . 
       FIG. 3  is a left-side cross-sectional view of the roller shade system  100  taken across the sectional line shown in  FIG. 2  showing the first side channel  112 . A drive system, such as, for example, a motor drive unit  125 , may be coupled to the roller tube  120  to allow for control of the rotation of the roller tube by a user of the roller shade system  100 . The motor drive unit  125  may be physically located inside the roller tube  122  (as shown in  FIG. 3 ) or may be mounted externally to the roller tube. An example of the motor drive unit  125  is described in greater detail in U.S. Pat. No. 6,983,783, issued Jan. 10, 2006, entitled MOTORIZED SHADE CONTROL SYSTEM, the entire disclosure of which is hereby incorporated by reference. 
     The roller shade system  100  includes a tensioning cord  130 , which may comprise a stainless steel cable, a liquid crystal polymer cable (such as Vectran™ cable manufactured by Cortland Cable, Inc.), or any suitable cord, cable, rope, or line. The tensioning cord  130  is operatively coupled between the roller tube  122  and the hembar  124  at the second fabric end of the shade fabric  120 .  FIG. 3   a  is a simplified left-side schematic view of the roller shade system  100  showing the cord  130  operatively coupled between the roller tube  122  and the hembar  124 . The tensioning cord  130  is windingly received around a cord-receiving portion  132 A (e.g., a cylindrical spool) at a first tube end of the roller tube  122  as shown in  FIG. 3 .  FIG. 4  is an enlarged detail of the left-side cross-sectional view of the roller shade system  100  of  FIG. 3  showing the first end of the roller tube  122  in greater detail. 
     The tensioning cord  130  is coupled to a pulley system comprising a first pulley  134 A, a second pulley  136 B, and a third pulley  138 A, which are located adjacent the second frame end  118 . Specifically, the tensioning cord  130  is windingly received by the first, second, and third pulleys  134 A,  136 A,  138 A, such that the third pulley  138 A windingly receives a portion of the tensioning cord between the portions of the tensioning cord presently received by the first and second pulleys  134 A,  136 A.  FIG. 5  is an enlarged detail of the left-side cross-sectional view (of  FIG. 3 ) and  FIG. 6  is a partial perspective view of the roller shade system  100  showing the first, second, and third pulleys  134 A,  136 A,  138 A in greater detail. The first and second pulleys  134 A,  136 A are directly coupled to the first side channel  112  of the frame  110 . However, the third pulley  138 A is operatively coupled to the first side channel  112  of the frame  110  via a spring  140 A, such that the tensioning cord  130  is spring-biased to pull the hembar  124  towards the second frame end  118 . Accordingly, the shade fabric  120  is held taut between the roller tube  122  and the hembar  124 , such that there is minimal sagging of the shade fabric when the roller shade system  100  is mounted in a non-vertical plane. The first, second, and third pulleys  134 A,  136 A,  138 A and the spring  140 A are hid from the view of the user by the first and second flanges  126 A,  128 B of the first side channel  112 . 
     The first side channel  112  is sized such that there is an abundance of space for the spring  140 A to occupy. Accordingly, the spring  140 A may be then sized appropriately large to accommodate for different thicknesses and surface areas of the shade fabric  120  received around the roller tube  122 . Therefore, the roller shade system  100  is easily scaled to thus mount roller shades having different shade fabric thicknesses, weights, and sizes (i.e., surface areas). 
     When the motor drive unit  125  rotates the roller tube  122 , the hembar  124  is operable to translate between the first frame end  116  and the second frame end  118 . Specifically, as the roller tube  122  rotates to wind up the tensioning cord  130 , the hembar  124  is pulled by the tensioning cord and moves towards the second frame end  118  of the frame  110 . When the roller tube  122  is rotated such that the shade fabric  120  is wound up, the hembar  124  is pulled towards the first frame end  116 . 
       FIG. 7  is a front cross-sectional view of the roller shade system  100  taken across the sectional line shown in  FIG. 3  showing both the first and second side channels  112 ,  114 . In the second side channel  114 , the roller shade system  100  also include a second pulley system (including first, second, and third pulleys  134 B,  136 B,  138 B) and a second spring  140 B, which operate in the same fashion as the first, second, and third pulleys  134 A,  136 A,  138 B and the spring  140 A of the first side channel  112  as described above. The pulley systems in each of the side channels  112 ,  114  provide for equal forces to be applied to the hembar  124 , thus allowing the hembar to remain parallel with the first and second frame ends  116 ,  118  as the hembar translates across the frame  110 . The pulley systems and the springs  140 A,  140 B also operate to reduce the stress applied to the motor drive unit  125  in the roller tube  122 . 
     The roller tube  122  includes a second cord-receiving portion  132 B at a second tube end that is rotatably coupled to the second side channel  114 . The tensioning cord  130  comprises a single cord that extends from the cord-receiving portions  132 A,  132 B of the roller tube  122  through a hembar channel  142  of the hembar  124  and through each of the pulley systems of the first and second side channels  112 ,  114 . The springs  140 A,  14 B may be equal in size, such that the forces applied to the hembar  124  by the tensioning cord on each side of the roller shade system  100  are approximately the same. Alternatively, the roller shade system  100  could comprise a single larger spring in one of the side channels  112 ,  114 . Since the tensioning cord  130  extends through the hembar  124  through both side channels  112 ,  114 , the single larger spring can be sized to appropriately tension the hembar  124  on both sides of the roller shade system  100 . 
     The tensioning cord  130  comprises a first cord end windingly received by the first cord-receiving portion  132 A and a second cord end windingly received by the second cord-receiving portion  132 B, such that the first and second cord ends are windingly received about the roller tube  122 . The tensioning cord  130  comprises a first tensioning cord portion  130 A in the first side channel  112  (from the first hembar end of the hembar  124  to the first cord-receiving portion  132 A) and a second tensioning cord portion  130 B in the second side channel  114  (from the second hembar end of the hembar  124  to the second cord-receiving portion  132 B). Alternatively, the first and second tensioning cord portions  130 A,  130 B could be two separate tensioning cords having ends fixedly attached to the respective first and second hembar ends of the hembar  124 . If two separate tensioning cords are provided (i.e., first and second tensioning cord portions  130 A,  130 B), a single spring may not be provided in one of the first and second side channels  112 ,  114 , i.e., springs  140 A,  140 B are provided in each of the first and second side channels, respectively. 
     When the roller shade system  100  is installed in the opening, the structure of the frame  110  minimizes the stresses applied to the building structure from the tension in the roller shade system  100 . The tension in the shade fabric  120  and the tensioning cord  130  applies forces on the first and second frame ends  116 ,  118  to pull the frame ends towards each other. Since the side channels  112 ,  114  are connected between the first and second frame ends  116 ,  118 , the forces of the roller shade system  110  are contained in the frame  110 , thus minimizing the forces applied by the roller shade system to the building structure. 
       FIG. 8  is an enlarged detail of the front cross-sectional view of  FIG. 7  showing the first side channel  112  and the first hembar end of the hembar  124  in greater detail.  FIG. 9  is a bottom cross-sectional view of the roller shade system  100  taken across the sectional line shown in  FIG. 2 .  FIG. 10  is an enlarged detail of the bottom cross-sectional view of the roller shade system  100  of in  FIG. 9  showing the first side channel  112  in greater detail.  FIG. 11  is a perspective view of the first hembar end of the hembar  124  without the shade fabric  120  and the tensioning cord  130  shown. Note the second hembar end of the hembar  124  is identical to the first hembar end shown in  FIG. 11 . 
     The first hembar end of the hembar  124  includes a first hembar pulley  144 A. The tensioning cord  130  extends from the first pulley  134 A and is windingly received by the first hembar pulley  144 A. The tensioning cord  130  extends from the first hembar pulley  144 A through the hembar channel  142  of the hembar  124  to a second hembar pulley  144 B at the second hembar end. As the hembar  124  is transitioning across the frame  110 , the hembar remains parallel with the first and second frame ends  116 ,  118  even if the tensioning cord winds differently in each of the first and second cord-receiving portions  132 A,  132 B of the roller tube  122 . For example, the tensioning cord  130  may wind up neatly in the first cord-receiving  132 A, but may wind up in an over-lapping fashion in the second cord-receiving portion  132 B, thus shortening the effective length of the tensioning cord. However, since the tensioning cord  130  extends through the hembar channel  142  of the hembar  124  and is enabled (by the hembar pulleys  144 A,  144 B) to move through the hembar, the portion of the tensioning cord extending from the hembar  124  to the roller tube  122  in each of the side channels  112 ,  114  remains approximately the same, thus allowing the hembar to remain parallel with the first and second frame ends  116 ,  118 . 
     The hembar  124  also includes fabric-receiving slots  146 ,  148  in which the shade fabric  120  may be fastened to the hembar ( FIG. 11 ). The method of attaching the shade fabric  120  to the fabric-receiving slots  146 ,  148  of the hembar  124  is described in greater detail in U.S. patent application Ser. No. 11/890,186, filed Aug. 3, 2007, entitled HEMBAR FOR A SHADE FABRIC AND ASSEMBLY METHOD, the entire disclosure of which is hereby incorporated by reference. 
     The first and second hembar ends of the hembar  124  include respective first and second hembar wheels  150 A,  150 B. The first and second hembar wheels  150 A,  150 B are received within the hembar slots  152 A,  152 B of the first and second side channels  112 ,  114 , respectively. Referring to  FIG. 10 , the first hembar slot  152 A is formed between the first flange  126 A and an interior wall  154 A. A sidewall  156 A of the first hembar slot  152 A extends from the first flange  126 A to the interior wall  154 A. The first hembar wheel  150 A is adapted to roll along a contact surface defined by the interior wall  154 A, such that the hembar  124  is operable to translate across the frame  110 . The first sidewall  156 A defines a non-linear surface, i.e., includes an indentation  158 A, which allows for rolling contact rather than sliding contact between the side of the first hembar wheel  150 A and the first sidewall  156 A. Note that the second hembar slot  152 B of the second side channel  114  has an identical structure to the first hembar slot  152 A of the first side channel  112 . Specifically, the second hembar slot  152 B is formed between the first flange  126 B and an interior wall  154 B of the second side channel  114  defining a non-linear sidewall  156 B having an indentation  158 B. 
     Tensioning adjustment means, e.g., tensioning screws  160 A,  160 B, are provided in each of the first and second side channels  112 ,  114  to allow for adjustment of the amount of force applied by the tensioning cord  130  on the hembar  124 .  FIG. 12  is an enlarged detail of the left-side cross-sectional view of  FIG. 3  showing the tensioning screw  160 A of the first side channel  112  in greater detail. The tensioning screw  160 A is coupled to the interior wall  154 A of the side channel via two mounting legs  162 A. The tensioning screw  160 A is then coupled to the spring  140 A via a coupling plate  164 A. The tensioning screw  160 A comprises a threaded portion  166 A, which is screwed into the coupling plate  164 A, such that the tension in the spring  140 A may be increased when the tensioning screw  160 A is rotated in a first direction and the tension in the spring  140 A may be decreased when the tensioning screw is rotated in a second direction. The tensioning screw  160 A includes a ratchet head  168 A, such that the installer of the roller shade system  100  may easily rotate the tensioning screw (e.g., using a motorized ratchet tool) to adjust the tension in the spring  140 A and thus the tensioning cord  130 . The tensioning screw  160 B in the second side channel  114  has the same structure as the tensioning screw  160 A of the first side channel  112  and similarly includes mounting legs  162 B, a coupling plate  164 B, a threaded portion  166 B, and a ratchet head  168 B. Accordingly, after the roller shade system  100  is assembled in the frame  110 , but before the roller shade system is installed in the opening, the tension in the springs  140 A,  140 B may be adjusted using the tensioning screws  160 A,  160 B such that the appropriate amount of force is applied by the tensioning cord  130  onto the hembar  124 . 
     Accordingly, the roller shade system  100  may be easily tensioned and installed in an opening, such as a skylight or other window oriented in a non-vertical plane. Before the roller shade system is installed in the opening, the roller shade system is assembled in the free-standing frame  110 . The assembly of the roller shade system may occur at the installation site or at a manufacturing facility, such that the roller shade system is shipped as a “pre-hung” tensioned roller shade system. During the assembly of the roller shade system, the roller tube  122  is mounted between the first and second side channels  112 ,  114  of the frame  110  adjacent the first frame end  116 , and the first fabric end of the shade fabric  120  is coupled to the roller tube  122  and wound around the roller tube. The second fabric end of the shade fabric  120  is coupled to the hembar  124 . The tensioning cord  130  is extended through the hembar  124 , coupled to the pulleys  134 A- 138 B of the roller shade assembly  100 , and wound appropriately around the roller tube  122 . The springs  140 A,  140 B are installed in the side channels  112 ,  114 , such that the hembar is biased towards the second frame end  118 . Before the roller shade assembly  100  is installed in the opening, the tensioning screws  160 A,  160 B are adjusted to modify the amount of force applied to the tensioning cord  130  by the springs  140 A,  140 B. The frame  110  is then ready to be installed into the opening. 
       FIG. 13  is a left-side cross-sectional view of a roller shade system  200  according to a second embodiment of the present invention. Note that the view of  FIG. 13  is taken across the same sectional line as  FIG. 3  (i.e., as shown in  FIG. 2 ). Rather than including three separate pulleys  134 A,  136 A,  138 A in the first side channel  112 , the roller shade system  200  of  FIG. 13  includes one single pulley  138 A and one dual pulley  234 A, which comprises two pulleys located immediately adjacent each other and operable to rotate about the same axis.  FIG. 13   a  is a simplified left-side schematic view of the roller shade system  200  showing the interaction between the shade fabric  120 , the roller tube  122 , the hembar  124 , the tensioning cord  130 , the pulleys  234 A,  138 A, and the spring  140 A. The tensioning cord  130  is windingly received by the both pulleys of the dual pulley  234 A. The third pulley  138 A windingly receives a portion of the tensioning cord between the portions of the tensioning cord presently received by both pulleys of the dual pulley  234 A. The tensioning screw  160 A is attached to the second flange  128 A of the first side channel  112 . 
       FIG. 14  is a left-side cross-sectional view of a roller shade system  300  according to a third embodiment of the present invention, which is taken across the same sectional line as  FIG. 3  (i.e., as shown in  FIG. 2 ). The roller shade system  300  of  FIG. 14  includes one single pulley  338 A that windingly receives the tensioning cord  130 . The pulley  338 A is coupled to the frame  110  adjacent the second frame end  118  via a spring  340 A and a coupling plate  364 A.  FIG. 14   a  is a simplified left-side schematic view of the roller shade system  300  showing the interaction between the shade fabric  120 , the roller tube  122 , the hembar  124 , the tensioning cord  130 , the pulleys  338 A, and the spring  340 A. The spring  340 A is oriented in the reverse direction as in the roller shade systems  100 ,  200  of the first and second embodiments (e.g., rotated approximately 180°). Accordingly, the length of travel of the hembar  124  through hembar slots  352 A,  352 B of the roller shade system  300  according to the third embodiment is smaller than the length of travel of the hembar in roller shades systems  100 ,  200  of the first and second embodiments. 
     While the frame  110  of the roller shade systems  100 ,  200 ,  300  was described in the present application and shown in the figures as a substantially square frame having four sides, the present invention is not limited to square frames having four sides. For example, the frame  110  could have a rectangular shape. Further, the frame  110  could only three sides, for example, having the second frame end  118  removed. 
     As described above, the roller shade system  100 ,  200 ,  300  is tensioned by springs  140 A,  140 B located in and attached to the side channels  112 ,  114 . However, the locations of the springs of the present invention are not limited to the side channels  112 ,  114 .  FIG. 15  is a simplified front schematic view of a roller shade system  400  according to a fourth embodiment of the present invention. The roller shade system  400  includes two separate tensioning cords (i.e., first and second tensioning cord portions  430 A,  430 B), which are windingly received around respective pulleys  438 A,  438 B in the respective side channels  112 ,  114 . A single spring  470  is located inside the hembar  124  and is coupled between the first and second tensioning cord portions  430 A,  430 B to provide for the appropriate tensioning of the roller shade system  400 . An example of a roller shade system having a spring located inside the hembar is described in greater detail in U.S. Pat. No. 1,121,898, issued Dec. 22, 1914, entitled WINDOW SCREEN, the entire disclosure of which is hereby incorporated by reference. 
       FIG. 16  is a simplified front schematic view of a roller shade system  500  according to a fifth embodiment of the present invention. In the roller shade system  500 , first and second tensioning cord portions  530 A,  530 B are formed as part of a single tensioning cord (i.e., tensioning cord  530 ). The roller shade system  500  comprises a single spring  570 , which is located in the second frame end  118  and has a first spring pulley  572 A at a first spring end and a second spring pulley  572 B at a second spring end. The roller shade system  500  further comprises two pulleys  536 A,  538 A located in the first side channel  112  adjacent the second frame end  118 , and two pulleys  536 B,  538 B located in the second side channel  114  adjacent the second frame end. The pulleys  536 A,  538 A in the first side channel  112  operate to guide the first tensioning cord portion  530 A towards the first spring pulley  572 A, which windingly receives the first tensioning cord portion. The pulleys  536 B,  538 B in the second side channel  114  operate to guide the second tensioning cord portion  530 B towards the second spring pulley  572 B, which windingly receives the second tensioning cord portion. Since the spring  570  is located in the second frame end  118 , the spring may be sized appropriately large to accommodate for different thicknesses and surface areas of the shade fabric  120  received around the roller tube  122 . 
     Alternatively, two separate springs (not shown) could be included in the second frame end  118  rather than the single spring  570 . Both springs would be coupled to the second frame end  118  at first spring ends and comprises pulleys at second spring ends. The pulley of one spring would windingly receive the first tensioning cord portion  530 A, while the pulley of the other spring would windingly receive the second tensioning cord portion  530 B. A single tensioning cord or two separate tensioning cords could be used. 
       FIG. 17  is an enlarged front cross-sectional view of a roller shade system  600  according to a sixth embodiment of the present invention showing the first tube end of the roller tube  122  in greater detail. The roller shade system  600  comprises a first conical, grooved spool  610 A mounted adjacent the first tube end of the roller tube  122  and adapted to rotate about the tube axis as the roller tube rotates (i.e., the spool is connected to the roller tube). A second conical, grooved spool (not shown), which is a mirror-image of the first spool  610 A, is mounted to the second tube end of the roller tube  122 .  FIG. 18  is a perspective view of the spool  610 A.  FIG. 19  is an enlarged front cross-sectional view of the first tube end of the roller tube  122  and the first spool  610 A taken through the center of the roller tube. 
     The spool  610 A has a first spool end  612  having a first diameter D 1  and a second spool end  614  having a second diameter D 2  larger than the first diameter as shown in  FIG. 19 . The spool  610 A has a single groove  616  wrapping around the spool from the first spool end  612  to the second spool end  614 . The groove  616  receives the tensioning cord  130 , such that the first tensioning cord portion  130 A is windingly received about the first spool  610 A. The groove  616  allows the tensioning cord  130  to wind around the spool  610 A without overlapping of the tensioning cord (which can generate audible noise as the roller tube  120  is rotated). 
     The tensioning cord  130  is connected to the spool  610 A near the second spool end  614 . When the roller shade system  600  is closed (i.e., the hembar  116  is at the second frame end  118  and there is little or no shade fabric  120  wrapped around the roller tube  122 ), the tensioning cord  130  extends from a point on the spool  610 A near the first spool end  612 . When the roller shade system  600  is open (i.e., the hembar  116  is at the first frame end  116  and the maximum amount of shade fabric  120  is wrapped around the roller tube  122 ), the tensioning cord  130  extends from a point on the spool  610 A near the second spool end  614 . Accordingly, the point at which the tensioning cord  130  extends from the spool  610 A moves from the first spool end  612  towards the second spool end  614  as the shade fabric  120  is wrapped around the roller tube  122 . 
     As the shade fabric  120  is wrapped around the roller tube  122 , the shade fabric may track (i.e., shift) in the direction of the tube axis from one rotation to the next, for example, towards the first spool  610 A as shown in  FIG. 19 . Since the first spool end  612  has a smaller diameter than the second spool end  614 , the shade fabric  120  is able to extend over the first spool  610 A as the shade fabric wraps around the roller tube  122 . Because the point at which the tensioning cord  130  extends from the spool  610 A moves from the first spool end  612  towards the second spool end  614  as the shade fabric  120  is wrapped around the roller tube  122 , the tensioning cord does not interfere with the shade fabric  120  that overlaps the spool  610 A. Since the shade fabric is able to extend over the first spool  610 A, the fabric gaps between the side edges of the shade fabric  120  (when the shade fabric is fully closed) and the outer edges of the side channels  112 ,  114  may be minimized. 
     As the shade fabric  120  wraps around the roller tube  122 , a total diameter DTI of the roller tube  122  and the wrapped shade fabric  120  becomes larger. The spool  610 A is sized such that a diameter D T2  of the spool at the point at which the tensioning cord extends from the spool more closely matches the total diameter DTI of the roller tube  122  and the wrapped shade fabric  120  as the hembar  116  travels between the first frame end  116  and the second frame end  118  of the frame  110 . In other words, the diameter of the roller tube  122  and the wrapped shade fabric  120  at the point at which the shade fabric extends from the roller tube more closely matches the diameter of the spool  610 A at the point at which the tensioning cord  130  extends from the spool as the roller tube and the spool are rotated and the point at which the tensioning cord extends from the spool moves from the first spool end  612  towards the second spool end  614 . This allows the torque on the motor  125  to be minimized and provides a more constant tension in the shade fabric  120  and the tensioning cord  130 , which improves the aesthetic appearance of the shade fabric. 
     Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.