Patent Publication Number: US-11639631-B2

Title: Window shade and actuating system thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to U.S. provisional patent application No. 62/943,484 filed on Dec. 4, 2019, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to window shades, and actuating systems used in window shades. 
     2. Description of the Related Art 
     Some window shades may have a bottom rail and an intermediate rail that can be adjusted independent of each other. This type of window shades can offer differential light transmission regions above and below the intermediate rail. However, the ability to separately displace the bottom rail and the intermediate rail may result in undesirable interaction between the bottom rail and the intermediate rail during operation if no adequate restricting mechanisms were provided. Moreover, the window shade may undesirably rise if the user continues operating after the window shade reaches a lowest position. 
     Therefore, there is a need for an improved actuating system that can be used in window shades and address at least the foregoing issues. 
     SUMMARY 
     The present application describes a window shade and an actuating system for use with the window shade that can address the foregoing issues. 
     According to an embodiment, the actuating system includes a first rotary axle and a second rotary axle rotatable independent of each other, the first rotary axle being rotatable for displacing a bottom part of a window shade, and the second rotary axle being rotatable for displacing an intermediate rail of a window shade, and a limiting mechanism including a mount support, and a first and a second sliding part respectively connected with the mount support, the first sliding part being movably linked to the first rotary axle, and the second sliding part being movably linked to the second rotary axle. The first sliding part slides in a first direction when the first rotary axle rotates for lowering the bottom part and in a second direction opposite to the first direction when the first rotary axle rotates for raising the bottom part, the second sliding part slides in the first direction when the second rotary axle rotates for lowering the intermediate rail and in the second direction when the second rotary axle rotates for raising the intermediate rail, and the first sliding part is prevented from sliding in the second direction via a contact between the first sliding part and the second sliding part. 
     Moreover, the application describes a window shade that incorporates the actuating system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating an embodiment of a window shade; 
         FIG.  2    is a perspective view illustrating the window shade having a bottom part and an intermediate rail lowered from a head rail; 
         FIG.  3    is a perspective view illustrating the window shade with the bottom part and the intermediate rail in a fully raised configuration; 
         FIG.  4    is a top view of the window shade; 
         FIG.  5    is an exploded view illustrating a construction of the window shade; 
         FIG.  6    is an exploded view illustrating a construction of a control module provided in an actuating system of the window shade; 
         FIG.  7    is a cross-sectional view of the control module shown in  FIG.  6   ; 
         FIG.  8    is an exploded view illustrating a limiting mechanism provided in the actuating system of the window shade; 
         FIG.  9    is a cross-sectional view of the limiting mechanism shown in  FIG.  8   ; 
         FIG.  10    is a perspective view illustrating a casing portion provided in the limiting mechanism; 
         FIG.  11    is a perspective view illustrating a sliding part provided in the limiting mechanism; 
         FIG.  12    is a perspective view illustrating another sliding part provided in the limiting mechanism; 
         FIG.  13    is a cross-sectional view illustrating the limiting mechanism in a state where the intermediate rail and the bottom part of the window shade are fully raised; 
         FIG.  14    is a cross-sectional view illustrating the limiting mechanism in a state where the bottom part is lowered to a lowest position with the intermediate rail remaining fully raised; 
         FIG.  15    is a cross-sectional view illustrating the limiting mechanism in a state where the bottom part and the intermediate rail are fully lowered; 
         FIG.  16    is an exploded view illustrating a variant construction of the limiting mechanism; 
         FIG.  17    is a cross-sectional view of the limiting mechanism shown in  FIG.  16   ; 
         FIG.  18    is a cross-sectional view illustrating the limiting mechanism of  FIGS.  16  and  17    in a state where the intermediate rail and the bottom part of the window shade are fully raised; 
         FIG.  19    is a cross-sectional view illustrating the limiting mechanism of  FIGS.  16  and  17    in a state where the bottom part is lowered to a lowest position with the intermediate rail remaining fully raised; 
         FIG.  20    is a cross-sectional view illustrating the limiting mechanism of  FIGS.  16  and  17    in a state where the bottom part and the intermediate rail are fully lowered; 
         FIG.  21    is an exploded view illustrating another variant construction of the limiting mechanism; 
         FIG.  22    is a cross-sectional view of the limiting mechanism shown in  FIG.  21   ; 
         FIG.  23    is a cross-sectional view illustrating the limiting mechanism of  FIGS.  21  and  22    in a state where the intermediate rail and the bottom part of the window shade are fully raised; 
         FIG.  24    is a cross-sectional view illustrating the limiting mechanism of  FIGS.  21  and  22    in a state where the bottom part is lowered to a lowest position with the intermediate rail remaining fully raised; and 
         FIG.  25    is a cross-sectional view illustrating the limiting mechanism of  FIGS.  21  and  22    in a state where the bottom part and the intermediate rail are fully lowered. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIGS.  1 - 3    are perspective views respectively illustrating an embodiment of a window shade  100  in different states,  FIG.  4    is a top view of the window shade  100 , and  FIG.  5    is an exploded view of the window shade  100 . Referring to  FIGS.  1 - 5   , the window shade  100  can include a head rail  102 , a bottom part  104 , an intermediate rail  106 , a shading structure  108  and an actuating system  110 . 
     The head rail  102  may be affixed at a top of a window frame, and can have any desirable shapes. According to an example of construction, the head rail  102  can have an elongate shape including a cavity for at least partially receiving the actuating system  110  of the window shade  100 . When the window shade  100  is installed on a window, attachment brackets  112  can be used to affix the head rail  102  on a window frame. 
     The bottom part  104  can be suspended from the head rail  102  with a plurality of suspension cords  114 . According to an example of construction, the bottom part  104  may be an elongate rail having a channel adapted to receive to the attachment of the shading structure  108 . 
     The intermediate rail  106  can be disposed between the head rail  102  and the bottom part  104 , and can be suspended from the head rail  102  with a plurality of suspension cords  116 . The intermediate rail  106  may also have an elongate shape having a channel adapted to receive an attachment of the shading structure  108 . Moreover, a plurality of guiding elements  113  may be provided in the intermediate rail  106  for facilitating the passage of the suspension cords  114  through the intermediate rail  106 . The guiding elements  113  may exemplary include grommets affixed to the intermediate rail  106 . 
     The shading structure  108  may exemplary have a cellular structure, which may include, without limitation, honeycomb structures. However, it will be appreciated that the shading structure  108  may have any suitable structure that can be expanded and collapsed between the bottom part  104  and the intermediate rail  106 . The shading structure  108  is disposed between the intermediate rail  106  and the bottom part  104 , and has two opposite ends  108 A and  108 B respectively disposed adjacent to the intermediate rail  106  and the bottom part  104 . For example, the end  108 A of the shading structure  108  may be provided with a strip  115  that is engaged with the intermediate rail  106  so as to attach the end  108 A of the shading structure  108  to the intermediate rail  106 , and the other end  108 B of the shading structure  108  may be likewise attached to the bottom part  104  via a strip  117 . Two end caps  118 A and  118 B may respectively close two opposite ends of the intermediate rail  106  so as to restrain the strip  115  inside the intermediate rail  106 , and two end caps  120 A and  120 B may respectively close two opposite ends of the bottom part  104  so as to retrain the strip  117  inside the bottom part  104 . According to an example of construction, the bottom part  104  may further carry a weighing element  122  for improved stability during use. 
     Referring to  FIGS.  1 - 3   , each of the bottom part  104  and the intermediate rail  106  is independently movable vertically relative to the head rail  102  for setting the window shade  100  to a desirable configuration. For example, the bottom part  104  may be lowered away from the head rail  102  and the intermediate rail  106  to expand the shading structure  108  as shown in  FIG.  1   , or raised toward the head rail  102  and the intermediate rail  106  to collapse the shading structure  108  as shown in  FIG.  3   . Moreover, the bottom part  104  and the intermediate rail  106  may be lowered away from the head rail  102  to form a gap  124  for light passage between the head rail  102  and the intermediate rail  106 , as shown in  FIG.  2   . The vertical position of the bottom part  104  and the vertical position of the intermediate rail  106  relative to the head rail  102  may be controlled with the actuating system  110 . 
     Referring to  FIGS.  1 - 5   , the actuating system  110  is assembled with the head rail  102 , and is operable to displace the bottom part  104  and the intermediate rail  106  relative to the head rail  102  for adjustment. The actuating system  110  can include a rotary axle  130  and a plurality of cord winding units  132  rotationally coupled to the rotary axle  130 , a control module  134  operatively coupled to the rotary axle  130 , a rotary axle  136  and a plurality of cord winding units  138  rotationally coupled to the rotary axle  136 , a control module  140  operatively coupled to the rotary axle  136 , and a limiting mechanism  142  respectively coupled to the rotary axles  130  and  136 . 
     The rotary axle  130  is respectively coupled to the cord winding units  132 , and can rotate about a rotation axis  144 . Each of the cord winding units  132  is respectively connected with the bottom part  104  via one suspension cord  114 , and is operable to wind the suspension cord  114  for raising the bottom part  104  and to unwind the suspension cord  114  for lowering the bottom part  104 . For example, the cord winding unit  132  may include a rotary drum (not shown) that is rotationally coupled to the rotary axle  130  and is connected with one end of the suspension cord  114 , and another end of the suspension cord  114  can be connected with the bottom part  104 , whereby the rotary drum can rotate along with the rotary axle  130  to wind or unwind the suspension cord  114 . Since the cord winding units  132  are commonly coupled to the rotary axle  130 , the cord winding units  132  can operate in a concurrent manner for winding and unwinding the suspension cords  114 . 
     The control module  134  is coupled to the rotary axle  130 , and is operable to drive the rotary axle  130  to rotate in either direction about the rotation axis  144  for raising or lowering the bottom part  104 . According to an example of construction, the control module  134  includes an operating member  146  that can hang downward from the head rail  102  and is operable to cause the rotary axle  130  to rotate in either direction for raising or lowering the bottom part  104 . The operating member  146  can have a looped structure, which can include, without limitation, a looped bead chain, a looped cord, and the like. 
     In conjunction with  FIGS.  1 - 5   ,  FIG.  6    is an exploded view illustrating a construction of the control module  134 , and  FIG.  7    is a cross-sectional view of the control module  134 . Referring to  FIGS.  1 - 7   , the control module  134  can include the operating member  146 , a housing  148 , a bracket  150 , one or more spring  152 , a wheel  154 , and an axle coupling part  156 . 
     The housing  148  can have an inner wall  158  that delimits an inner cavity  158 A adapted to receive the spring  152 . The bracket  150  can be fixedly connected with the housing  148 , and can close one side of the inner cavity  158 A. The control module  134  can be mounted to the head rail  102  with the housing  148  and the bracket  150  fixedly attached to the head rail  102 . 
     Each spring  152  can be a torsion spring having two prongs  152 A and  152 B spaced apart from each other, and can be assembled inside the housing  148  in tight contact with the inner wall  158  and around the rotation axis  144 . Each of the two prongs  152 A and  152 B can be respectively pushed in one direction for causing the spring  152  to contract and loosen its frictional contact with the inner wall  158  of the housing  148 , and in an opposite direction for causing the spring  152  to further expand and tighten its frictional contact with the inner wall  158  of the housing  148 . 
     The wheel  154  can be pivotally connected with the bracket  150  so as to be rotatable about the rotation axis  144  relative to the housing  148  and the bracket  150 . For example, the bracket  150  can be fixedly connected with a shaft portion  150 A, and the wheel  154  can be pivotally connected about the shaft portion  150 A. Moreover, the wheel  154  may have a circumference configured to engage with the operating member  146 . In the illustrated embodiment, the operating member  146  is exemplary a bead chain, and the circumference of the wheel  154  may include a plurality of notches  154 A that can engage with the bead chain. Pulling on the operating member  146  thus can drive the wheel  154  to rotate in either direction. For example, the operating member  146  may have an outer portion  146 A and an inner portion  146 B, and pulling downward one of the outer and inner portions  146 A and  146 B may drive the wheel  154  to rotate in one direction while pulling downward the other one of the outer and inner portions  146 A and  146 B may drive the wheel  154  to rotate in an opposite direction. 
     The wheel  154  can further be fixedly connected with an actuating part  160  having a rib  160 A, whereby the wheel  154  and the actuating part  160  are rotatable in unison. According to an example of construction, the actuating part  160  may be fastened to the wheel  154 . According to another example of construction, the actuating part  160  may be formed integrally with the wheel  154 . The actuating part  160  can axially protrude at a side of the wheel  154 , and can extend through the spring  152  with the rib  160 A positioned in a gap G between the two prongs  152 A and  152 B of the spring  152 . Accordingly, a rotation of the wheel  154  in either direction can result in the rib  160 A selectively pushing against one of the two prongs  152 A and  152 B for causing the spring  152  to contract and loosen its frictional contact with the inner wall  158  of the housing  148 . For example, the rib  160 A can push against the prong  152 A of the spring  152  for causing the spring  152  to loosen when the wheel  154  rotates in one direction, and the rib  160 A can push against the prong  152 B of the spring  152  for causing the spring  152  to loosen when the wheel  154  rotates in another opposite direction. 
     Referring to  FIGS.  5  and  6   , the axle coupling part  156  can be rotationally coupled to the rotary axle  130 , and can have a tongue  162  that extends through the spring  152  and at least partially around the rotation axis  144 . The tongue  162  is located outside the gap G between the two prongs  152 A and  152 B of the spring  152  so that a rotation of the rotary axle  130  and the axle coupling part  156  in either direction can result in the tongue  162  selectively pushing against one of the two prongs  152 A and  152 B for causing the spring  152  to expand and tighten its frictional contact with the inner wall  158  of the housing  148 . 
     For lowering the bottom part  104 , a user can pull downward one of the outer portion  146 A and the inner portion  146 B of the operating member  146  (e.g., the outer portion  146 A), which urges the wheel  154  to rotate in one direction and causes the rib  160 A of the actuating part  160  to push against one of the two prongs  152 A and  152 B for causing the spring  152  to contract and loosen its frictional contact with the inner wall  158  of the housing  148 . The loosened spring  152  then can rotate along with the wheel  154  and push against the tongue  162  of the axle coupling part  156 , which consequently causes the axle coupling part  156  and the rotary axle  130  to rotate in unison in the same direction along with the spring  152  and the wheel  154  for lowering the bottom part  104 . 
     For raising the bottom part  104 , a user can pull downward the other one of the outer portion  146 A and the inner portion  146 B of the operating member  146  (e.g., the inner portion  146 B), which urges the wheel  154  to rotate in an opposite direction and cause the rib  160 A of the actuating part  160  to push against the other one of the two prongs  152 A and  152 B for causing the spring  152  to contract and loosen its frictional contact with the inner wall  158  of the housing  148 . The loosened spring  152  then can likewise rotate along with the wheel  154  and push against the tongue  162  of the axle coupling part  156 , which consequently causes the axle coupling part  156  and the rotary axle  130  to rotate in unison in the same direction along with the spring  152  and the wheel  154  for raising the bottom part  104 . 
     When the operating member  146  is not operated and the wheel  154  remains stationary, the suspended weight of the bottom part  104  and the shading structure  108  can apply a torque on the axle coupling part  156  and the rotary axle  130 , which biases the tongue  162  to push against one of the two prongs  152 A and  152 B of the spring  152  for causing the spring  152  to expand and increase its frictional contact with the inner wall  158  of the housing  148 . This frictional contact between the spring  152  and the housing  148  can block rotation of the spring  152 , the axle coupling part  156  and the rotary axle  130  about the rotation axis  144  and keep the bottom part  104  at any desirable positions, such as the different positions shown in  FIGS.  1 - 3   . 
     Referring to  FIGS.  1 - 7   , the rotary axle  136  is respectively coupled to the cord winding units  138 , and can rotate independent of the rotary axle  130 . According to an example of construction, the rotary axle  136  can be disposed substantially coaxial to the rotary axle  130 , and can rotate about the same rotation axis  144 . For example, the rotary axles  130  and  136  may be spaced apart from each other along the rotation axis  144 . Each of the cord winding units  138  is respectively connected with the intermediate rail  106  via one suspension cord  116 , and is operable to wind the suspension cord  116  for raising the intermediate rail  106  and to unwind the suspension cord  116  for lowering the intermediate rail  106 . For example, the cord winding unit  138  may include a rotary drum (not shown) that is rotationally coupled to the rotary axle  136  and is connected with one end of the suspension cord  116 , and another end of the suspension cord  116  can be connected with the intermediate rail  106 , whereby the rotary drum can rotate along with the rotary axle  136  to wind or unwind the suspension cord  116 . Since the cord winding units  138  are commonly coupled to the rotary axle  136 , the cord winding units  138  can operate in a concurrent manner for winding and unwinding the suspension cords  116 . 
     The control module  140  is coupled to the rotary axle  136 , and is operable independently of the control module  134  to drive the rotary axle  136  to rotate in either direction about the rotation axis  144  for raising or lowering the intermediate rail  106 . According to an example of construction, the control module  140  includes an operating member  164  that can hang downward from the head rail  102  and is operable to cause the rotary axle  136  to rotate in either direction for raising or lowering the intermediate rail  106 . The operating member  164  can have a looped structure, which can include, without limitation, a looped bead chain, a looped cord, and the like. The control module  140  may be similar to the control module  134  in construction, and the two control modules  134  and  140  may be respectively disposed at two opposite ends of the head rail  102 . 
     In conjunction with  FIGS.  1 - 5   ,  FIGS.  8  and  9    are respectively an exploded view and a cross-sectional view illustrating a construction of the limiting mechanism  142 . Referring to  FIGS.  1 - 5 ,  8  and  9   , the limiting mechanism  142  can include a mount support  166 , a sliding part  168  and an extension part  170  coupled to the rotary axle  130 , and a sliding part  172  and an extension part  174  coupled to the rotary axle  136 . 
     The mount support  166  can receive the sliding parts  168  and  172 , and can be fixedly connected with the head rail  102 . According to an example of construction, the mount support  166  may be a housing including two casing portions  166 A and  166 B that can be fixedly attached to each other to define a hollow interior adapted to receive the sliding parts  168  and  172 .  FIG.  10    is a perspective view illustrating the casing portion  166 A alone. 
     In conjunction with  FIGS.  8  and  9   ,  FIG.  11    is a perspective view illustrating the sliding part  168  alone under an angle of view differing from that of  FIG.  8   . Referring to  FIGS.  8 ,  9  and  11   , the sliding part  168  is connected with the mount support  166 , and is movably linked to the rotary axle  130  so that a rotation of the rotary axle  130  causes the sliding part  168  to slide along the rotation axis  144  relative to the mount support  166 . For example, the sliding part  168  can be rotationally coupled to the rotary axle  130  and axially slidable relative to the rotary axle  130 , and can have a threaded portion  169  engaged with a threaded portion  176  provided in the mount support  166 . The threaded portions  169  and  176  can be exemplarily formed on a circular or arcuate surface having an axis substantially coaxial to the rotation axis  144 . This connection allows the sliding part  168  to concurrently rotate about and slide along the rotation axis  144  as the rotary axle  130  rotates about the rotation axis  144 . 
     In conjunction with  FIGS.  8  and  9   ,  FIG.  12    is a perspective view illustrating the sliding part  172  alone under an angle of view differing from that of  FIG.  8   . Referring to  FIGS.  8 ,  9  and  12   , the sliding part  172  is also connected with the mount support  166 , and is movably linked to the rotary axle  136  so that a rotation of the rotary axle  136  causes the sliding part  172  to slide along the rotation axis  144  relative to the mount support  166 . For example, the sliding part  172  can be rotationally coupled to the rotary axle  136  and axially slidable relative to the rotary axle  136 , and can have a threaded portion  173  engaged with the threaded portion  176  of the mount support  166 . The threaded portion  173  can be exemplarily formed on a circular or arcuate surface having an axis substantially coaxial to the rotation axis  144 . This connection allows the sliding part  172  to concurrently rotate about and slide along the rotation axis  144  as the rotary axle  136  rotates about the rotation axis  144 . 
     With the aforementioned construction, the sliding part  168  can slide in a direction A 1  away from the sliding part  172  when the rotary axle  130  rotates for lowering the bottom part  104  and in a direction A 2  (i.e., opposite to the direction A 1 ) toward the sliding part  172  when the rotary axle  130  rotates for raising the bottom part  104 . The sliding part  172  can slide in the direction A 1  toward the sliding part  168  when the rotary axle  136  rotates for lowering the intermediate rail  106  and in the direction A 2  away from the sliding part  168  when the rotary axle  136  rotates for raising the intermediate rail  106 . The sliding part  168  can thereby have a course that can be delimited by the sliding part  172  and a stop structure  177 A provided in the mount support  166 , wherein the stop structure  177 A may be provided on an inner sidewall of the mount support  166  (e.g., on the casing portion  166 B of the mount support  166 ). This course of the sliding part  168  can correspond to a vertical course of the bottom rail  104  between a lowest position relative to the head rail  102  and the intermediate rail  106 . Correspondingly, the sliding part  172  can have a course that can be delimited by the sliding part  168  and another stop structure  177 B provided in the mount support  166 , wherein the stop structure  177 B may be provided on an inner sidewall of the mount support  166  (e.g., on the casing portion  166 A of the mount support  166 ) opposite to the stop structure  177 A. This course of the sliding part  172  can correspond to a vertical course of the intermediate rail  106  between the bottom part  104  and a highest position of the intermediate rail  106  relative to the head rail  102 . 
     With the limiting mechanism  142  described herein, a contact between the sliding part  168  and the stop structure  177 A can prevent the bottom part  104  from moving downward relative to the head rail  102 , and can thereby stop the bottom part  104  at the lowest position relative to the head rail  102 . For facilitating an engagement of the sliding part  168  with the strop structure  177 A, the sliding part  168  may have a protrusion  168 A eccentric from the rotation axis  144  that is provided at one end of the sliding part  168 , which can contact and engage the strop structure  177 A to stop the bottom part  104  at the lowest position. Moreover, a contact between the sliding part  172  and the stop structure  177 B or a position of the sliding part  172  adjacent to the stop structure  177 B may correspond to a highest position of the intermediate rail  106  adjacent to the head rail  102 . For facilitating an engagement of the sliding part  172  with the strop structure  177 B, the sliding part  172  may have a protrusion  172 A (better shown in  FIG.  12   ) eccentric from the rotation axis  144  that is provided at one end of the sliding part  172 , which may contact and engage the strop structure  177 B to stop the intermediate rail  106  at its highest position. 
     On the other hand, a contact between the sliding part  168  and the sliding part  172  can prevent the sliding part  168  from sliding in the direction A 2 , which can stop the bottom rail  104  at a suitable distance from the intermediate rail  106  and prevent an upward displacement of the bottom part  104  that would undesirably push the intermediate rail  106  upward. The contact between the sliding part  168  and the sliding part  172  can also prevent the sliding part  172  from sliding in the direction A 1 , which can stop the intermediate rail  106  at a suitable distance from the bottom rail  104  and prevent a downward displacement of the intermediate rail  106  that would undesirably push the bottom part  104  downward. For facilitating an engagement between the sliding parts  168  and  172 , the sliding part  168  may have a protrusion  168 B (better shown in  FIG.  11   ) eccentric from the rotation axis  144  that is provided at another end of the sliding part  168  opposite to that of the protrusion  168 A, and the sliding part  172  may have a protrusion  172 B (better shown in  FIG.  8   ) eccentric from the rotation axis  144  that is provided at another end of the sliding part  172  opposite to that of the protrusion  172 A. The contact between the sliding part  168  and the sliding part  172  may be achieved via an engagement of the protrusion  168 B with the protrusion  172 B. 
     Referring to  FIGS.  8  and  9   , the extension part  170  can be provided for extending the course of the sliding part  168  (and thus the vertical course of the bottom part  104 ), wherein the sliding part  168  can be rotationally coupled to the rotary axle  130  via the extension part  170 . According to an example of construction, the rotary axle  130  can have a coupling portion  178 , and the extension part  170  can be respectively connected slidably with the sliding part  168  and the coupling portion  178  of the rotary axle  130 . The coupling portion  178  can be connected with an end of the rotary axle  130  for facilitating the assembly of the extension part  170 , and is rotatable in unison with the rotary axle  130 . For example, the end of the rotary axle  130  can be received in an opening  178 A provided in the coupling portion  178  so as to rotationally couple the coupling portion  178  to the rotary axle  130 . According to another example of construction, the coupling portion  178  may be formed integrally with the rotary axle  130 . 
     According to an example of construction, the sliding part  168 , the extension part  170  and the coupling portion  178  can be telescopically connected with one another. For example, the sliding part  168  can have a hollow interior  168 H in which a portion of the extension part  170  having a matching shape is slidably disposed, and the extension part  170  can have a hollow interior  170 H in which a portion of the coupling portion  178  having a matching shape is slidably disposed. With the construction described herein, the sliding part  168  and the extension part  170  can rotate in unison along with the coupling portion  178  and the rotary axle  130  about the rotation axis  144 , and meanwhile slide along the rotation axis  144  relative to each other and the coupling portion  178  of the rotary axle  130 . For example, the extension part  170  is slidable relative to the coupling portion  178  along the rotation axis  144  of the rotary axle  130  in the directions A 1  and A 2 , and the sliding part  168  is slidable relative to the extension part  170  and the coupling portion  178  along the rotation axis  144  of the rotary axle  130  in the directions A 1  and A 2 . 
     Referring to  FIGS.  8 ,  9  and  11   , an engagement structure may be provided for allowing the extension part  170  to slide along with the sliding part  168  in the directions A 1  and A 2  for retraction and extension relative to the coupling portion  178 . For example, this engagement structure may include two protrusions  168 C and  168 D provided on the sliding part  168  axially distant from each other, and a flange provided at one end of the extension part  170  that defines two opposite flange surfaces  170 C and  170 D. The sliding part  168  and the extension part  170  can slide in unison in the direction A 1  relative to the coupling portion  178  with the protrusion  168 C in contact with the flange surface  170 C, and the protrusion  168 C can be displaced away from the flange surface  170 C when the sliding part  168  slides in the direction A 2  relative to the extension part  170  and the coupling portion  178 . Moreover, the sliding part  168  and the extension part  170  can slide in unison in the direction A 2  relative to the coupling portion  178  with the protrusion  168 D in contact with the flange surface  170 D, and the protrusion  168 D can be displaced away from the flange surface  170 D when the sliding part  168  slides in the direction A 1  relative to the extension part  170  and the coupling portion  178 . 
     Referring to  FIGS.  8  and  9   , the extension part  174  can be likewise provided for extending the course of the sliding part  172  (and thus the vertical course of the intermediate rail  106 ), wherein the sliding part  172  can be rotationally coupled to the rotary axle  136  via the extension part  174 . According to an example of construction, the rotary axle  136  can have a coupling portion  180 , and the extension part  174  can be respectively connected slidably with the sliding part  172  and the coupling portion  180  of the rotary axle  136 . The coupling portion  180  can be connected with an end of the rotary axle  136  for facilitating the assembly of the extension part  174 , and is rotatable in unison with the rotary axle  136 . For example, the end of the rotary axle  136  can be received in an opening  180 A provided in the coupling portion  180  so as to rotationally couple the coupling portion  180  to the rotary axle  136 . According to another example of construction, the coupling portion  180  may be formed integrally with the rotary axle  136 . 
     According to an example of construction, the sliding part  172 , the extension part  174  and the coupling portion  180  can be telescopically connected with one another. For example, the sliding part  172  can have a hollow interior  172 H in which a portion of the extension part  174  having a matching shape is slidably disposed, and the extension part  174  can have a hollow interior  174 H in which a portion of the coupling portion  180  having a matching shape is slidably disposed. With the construction described herein, the sliding part  172  and the extension part  174  can rotate in unison along with the coupling portion  180  and the rotary axle  136  about the rotation axis  144 , and meanwhile slide along the rotation axis  144  relative to each other and the coupling portion  180  of the rotary axle  136 . For example, the extension part  174  is slidable relative to the coupling portion  180  along the rotation axis  144  of the rotary axle  136  in the directions A 1  and A 2 , and the sliding part  172  is slidable relative to the extension part  174  and the coupling portion  180  along the rotation axis  144  of the rotary axle  136  in the directions A 1  and A 2 . 
     An engagement structure may be provided for allowing the extension part  174  to slide along with the sliding part  172  in the directions A 1  and A 2  for retraction and extension relative to the coupling portion  180 . For example, this engagement structure may include two protrusions  172 C and  172 D provided on the sliding part  172  axially distant from each other, and a flange provided at one end of the extension part  174  that defines two opposite flange surfaces  174 C and  174 D. The sliding part  172  and the extension part  174  can slide in unison in the direction A 2  relative to the coupling portion  180  with the protrusion  172 C in contact with the flange surface  174 C, and the protrusion  172 C can be displaced away from the flange surface  174 C when the sliding part  172  slides in the direction A 1  relative to the extension part  174  and the coupling portion  180 . Moreover, the sliding part  172  and the extension part  174  can slide in unison in the direction A 1  relative to the coupling portion  180  with the protrusion  172 D in contact with the flange surface  174 D, and the protrusion  172 D can be displaced away from the flange surface  174 D when the sliding part  172  slides in the direction A 2  relative to the extension part  174  and the coupling portion  180 . 
     In conjunction with  FIGS.  1 - 12   ,  FIGS.  13 - 15    are cross-sectional views illustrating exemplary operation of the limiting mechanism  142 . Referring to  FIG.  13   , the limiting mechanism  142  is shown in a state where the bottom part  104  and the intermediate rail  106  are fully raised as shown in  FIG.  3   . The sliding part  172  can be adjacent to (with or without contacting) the stop structure  177 B (better shown in  FIG.  10   ) of the mount support  166 , the extension part  174  can be substantially retracted inside the sliding part  172 , and the coupling portion  180  of the rotary axle  136  can be substantially received inside the extending part  174 . Moreover, the sliding part  168  can be in contact with the sliding part  172 , and the extension part  170  can be extended relative to the sliding part  168  and the coupling portion  178  of the rotary axle  130 . 
     Referring to  FIGS.  1 ,  8 ,  9  and  14   , while the intermediate rail  106  remains stationary, the operating member  146  of the control module  134  can be operated to lower the bottom part  104  for expanding the shading structure  108 . As a result, the rotary axle  130  rotates in a direction that causes the sliding part  168  to concurrently rotate about the rotation axis  144  and slide in the direction A 1  away from the sliding part  172 . This movement of the sliding part  168  can result in the extension part  170  being rotated about the rotation axis  144  and gradually received inside the sliding part  168 . As the sliding part  168  slides in the direction A 1 , the protrusion  168 C of the sliding part  168  may contact the flange surface  170 C of the extension part  170  so that the sliding part  168  can urge the extension part  170  to slide in unison in the direction A 1  relative to the coupling portion  178  of the rotary axle  130 . Accordingly, the coupling portion  178  can be gradually received inside the extension part  170 . Once the bottom part  104  reaches a desired position, the user can release the operating member  146  of the control module  134 , and the sliding part  168  and the extension part  170  can accordingly stop moving. In case the bottom part  104  is lowered to a lowest position, the sliding part  168  can slide in the direction A 1  until the protrusion  168 A of the sliding part  168  engages the stop structure  177 A for stopping the sliding part  168 . When the bottom part  104  is in the lowest position, the sliding part  168  and the extension part  170  can be positioned as shown in  FIG.  14   , wherein the coupling portion  178  of the rotary axle  130  can be substantially received inside the extension part  170  and the extension part  170  can be substantially received inside the sliding part  168 . 
     Referring to  FIGS.  2 ,  8 ,  9  and  15   , while the bottom part  104  remains in a lowered position relative to the head rail  102 , the operating member  164  of the control module  140  can be operated for lowering the intermediate rail  106 . As a result, the rotary axle  136  rotates in a direction that causes the sliding part  172  to concurrently rotate about the rotation axis  144  and slide in the direction A 1  toward the sliding part  168 . This movement of the sliding part  172  can result in the extension part  174  being rotated about the rotation axis  144  and extended outside the sliding part  172 . As the sliding part  172  slides in the direction A 1 , the protrusion  172 D of the sliding part  172  may contact the flange surface  174 D of the extension part  174  so that the sliding part  172  can urge the extension part  174  to slide in unison in the direction A 1  relative to the coupling portion  180  of the rotary axle  136 . Accordingly, the coupling portion  180  gradually extends outside the extension part  174 . Once the intermediate rail  106  reaches a desired position, the user can release the operating member  164  of the control module  140 , and the sliding part  172  and the extension part  174  can accordingly stop moving. In case the intermediate rail  106  is lowered to a lowest position adjacent to the bottom part  104 , the sliding part  172  can slide in the direction A 1  until the protrusion  172 B of the sliding part  172  engages the protrusion  168 B of the sliding part  168  for stopping the sliding part  172 . Assuming that the bottom part  104  is in its lowest position relative to the head rail  102  and the intermediate rail  106  is lowered to its lowest position adjacent to the bottom part  104 , the sliding part  168 , the extension part  170 , the sliding part  172  and the extension part  174  can be positioned as shown in  FIG.  15   . In this configuration, the coupling portion  180  of the rotary axle  136  can be substantially extended outside the extension part  174  and the extension part  174  can be substantially extended outside the sliding part  172 , which is in contact with the sliding part  168 . 
     In case the bottom part  104  is to be raised for collapsing the shading structure  108 , the operating member  146  of the control module  134  can be operated to cause the rotary axle  130  to rotate in a direction that displaces the sliding part  168  in the direction A 2  toward the sliding part  172 . The sliding part  168  may concurrently rotate about the rotation axis  144  and slide in the direction A 2  until the protrusion  168 B of the sliding part  168  engages the protrusion  172 B of the sliding part  172 . Owing to the locking action exerted by the control module  140  on the rotary axle  136 , the sliding part  172  can be held in position and consequently prevent the sliding part  168  from further sliding in the direction A 2 . Further upward displacement of the bottom part  104  can thus be prevented. Accordingly, the limiting mechanism  142  can prevent undesirable upward displacement of the intermediate rail  106  caused by a rise of the bottom part  104 . 
     When the bottom part  104  is to be fully raised, a user first has to raise the intermediate rail  106  until it is positioned adjacent to the head rail  102 , which displaces the sliding part  172  in the direction A 2 . Then the operating member  146  of the control module  134  can be operated for raising the bottom part  104 . Accordingly, the sliding part  168  can slide in the direction A 2  until the sliding part  168  contacts the sliding part  172 , which can stop the bottom part  104  in the fully raised position. 
     In conjunction with  FIGS.  1 - 3   ,  FIGS.  16  and  17    are respectively an exploded view and a partial cross-sectional view illustrating a variant construction of the limiting mechanism  142  that may be applied in the actuating system  110  of the window shade  100 . Referring to  FIGS.  16  and  17   , the limiting mechanism  142  can likewise include the two sliding parts  168  and  172 , but does not have the extension parts  170  and  174  of the previous embodiment. Like previously described, the sliding part  168  has a threaded portion  169  engaged with the threaded portion  176  of the mount support  166  and is movably linked to the rotary axle  130  so that a rotation of the rotary axle  130  causes the sliding part  168  to slide along the rotation axis  144  relative to the mount support  166 . The sliding part  172  has a threaded portion  173  engaged with the threaded portion  176  of the mount support  166  and is movably linked to the rotary axle  136  so that a rotation of the rotary axle  136  causes the sliding part  172  to slide along the rotation axis  144  relative to the mount support  166 . 
     In the embodiment of  FIGS.  16  and  17   , the sliding parts  168  and  172  can be respectively mounted directly on the rotary axles  130  and  136 . For example, the sliding part  168  can have a hollow interior  168 K in which a portion of the rotary axle  130  having a matching shape is slidably disposed, whereby the sliding part  168  can rotate along with the rotary axle  130  about the rotation axis  144  and meanwhile slide along the rotation axis  144  relative to the rotary axle  130 . Likewise, the sliding part  172  can have a hollow interior  172 K in which a portion of the rotary axle  136  having a matching shape is slidably disposed, whereby the sliding part  172  can rotate along with the rotary axle  136  about the rotation axis  144  and meanwhile slide along the rotation axis  144  relative to the rotary axle  136 . 
     In conjunction with  FIGS.  1 - 3   ,  FIGS.  18 - 20    are cross-sectional views illustrating exemplary operation of the limiting mechanism  142  shown in  FIGS.  16  and  17   . Referring to  FIGS.  16 - 20   , the sliding parts  168  and  172  of the limiting mechanism  142  can operate similar to the previous embodiment. In  FIG.  18   , the limiting mechanism  142  is shown in a state where the bottom rail  104  and the intermediate rail  106  are fully raised such as shown in  FIG.  3   , wherein the protrusion  168 B of the sliding part  168  can be in contact with the protrusion  172 B of the sliding part  172 . 
     Referring to  FIGS.  1  and  19   , while the intermediate rail  106  remains stationary, the operating member  146  of the control module  134  can be operated to lower the bottom part  104  for expanding the shading structure  108 . As a result, the rotary axle  130  rotates in a direction that causes the sliding part  168  to concurrently rotate about the rotation axis  144  and slide on the rotary axle  130  in the direction A 1  away from the sliding part  172 . Once the bottom part  104  reaches a desired position, the user can release the operating member  146  of the control module  134 , and the sliding part  168  can accordingly stop moving. In case the bottom part  104  is lowered to a lowest position, the sliding part  168  can slide in the direction A 1  until the protrusion  168 A of the sliding part  168  engages the stop structure  177 A for stopping the sliding part  168  as shown in  FIG.  19   . 
     Referring to  FIGS.  2  and  20   , while the bottom part  104  remains in a lowered position relative to the head rail  102 , the operating member  164  of the control module  140  can be operated for lowering the intermediate rail  106 . As a result, the rotary axle  136  rotates in a direction that causes the sliding part  172  to concurrently rotate about the rotation axis  144  and slide on the rotary axle  136  in the direction A 1  toward the sliding part  168 . Once the intermediate rail  106  reaches a desired position, the user can release the operating member  164  of the control module  140 , and the sliding part  172  can accordingly stop moving. In case the intermediate rail  106  is lowered to a lowest position adjacent to the bottom part  104 , the sliding part  172  can slide in the direction A 1  until the protrusion  172 B of the sliding part  172  engages the protrusion  168 B of the sliding part  168  for stopping the sliding part  172 , as shown in  FIG.  20   . Like the previous embodiment, the limiting mechanism  142  shown in  FIGS.  16 - 20    can prevent undesirable upward displacement of the intermediate rail  106  caused by a rise of the bottom part  104 . 
     In conjunction with  FIGS.  1 - 3   ,  FIGS.  21  and  22    are respectively an exploded view and a cross-sectional view illustrating another variant construction of the limiting mechanism  142 . Referring to  FIGS.  21  and  22   , the limiting mechanism  142  can likewise include the two sliding parts  168  and  172 , but does not have the extension parts  170  and  174  of the embodiment shown in  FIGS.  8  and  9   . In the embodiment of  FIGS.  21  and  22   , the mount support  166  can be exemplarily a bracket, and can have two threaded portions  176 A and  176 B axially apart from each other. The threaded portions  176 A and  176 B can be exemplarily formed on circular or arcuate surfaces having an axis substantially coaxial to the rotation axis  144 . According to an example of construction, the threaded portions  176 A and  176 B can be respectively provided in two opposite sidewalls of the mount support  166 . The sliding part  168  has a threaded portion  169  engaged with the threaded portion  176 A of the mount support  166  and is movably linked to the rotary axle  130  so that a rotation of the rotary axle  130  causes the sliding part  168  to slide along the rotation axis  144  relative to the mount support  166 . The sliding part  172  has a threaded portion  173  engaged with the threaded portion  176 B of the mount support  166  and is movably linked to the rotary axle  136  so that a rotation of the rotary axle  136  causes the sliding part  172  to slide along the rotation axis  144  relative to the mount support  166 . 
     Referring to  FIGS.  21  and  22   , the sliding parts  168  and  172  can be respectively mounted directly on the rotary axles  130  and  136 . For example, the sliding part  168  can have a hollow interior  168 K in which a portion of the rotary axle  130  having a matching shape is slidably disposed, whereby the sliding part  168  can rotate along with the rotary axle  130  about the rotation axis  144  and meanwhile slide along the rotation axis  144  relative to the rotary axle  130 . Likewise, the sliding part  172  can have a hollow interior  172 K in which a portion of the rotary axle  136  having a matching shape is slidably disposed, whereby the sliding part  172  can rotate along with the rotary axle  136  about the rotation axis  144  and meanwhile slide along the rotation axis  144  relative to the rotary axle  136 . For a compact assembly, the sliding part  168  can have a channel  168 N adapted to receive at least partially the sliding part  172 . The protrusion  168 B can be provided at an end of the channel  168 N, and the protrusion  172 B can be provided at an end of the sliding part  172  that can be received in the channel  168 N. 
     In conjunction with  FIGS.  1 - 3   ,  FIGS.  23 - 25    are cross-sectional views illustrating exemplary operation of the limiting mechanism  142  shown in  FIGS.  21  and  22   . In  FIG.  23   , the limiting mechanism  142  is shown in a state where the bottom rail  104  and the intermediate rail  106  are fully raised such as shown in  FIG.  3   , wherein the sliding part  172  is received at least partially inside the channel  168 N of the sliding part  168  and the protrusion  168 B of the sliding part  168  is in contact with the protrusion  172 B of the sliding part  172  inside the channel  168 B. 
     Referring to  FIGS.  1  and  24   , while the intermediate rail  106  remains stationary, the operating member  146  of the control module  134  can be operated to lower the bottom part  104  for expanding the shading structure  108 . As a result, the rotary axle  130  rotates in a direction that causes the sliding part  168  to concurrently rotate about the rotation axis  144  and slide on the rotary axle  130  in the direction A 1 . Once the bottom part  104  reaches a desired position, the user can release the operating member  146  of the control module  134 , and the sliding part  168  can accordingly stop moving. In case the bottom part  104  is lowered to a lowest position, the sliding part  168  can slide in the direction A 1  until the protrusion  168 A of the sliding part  168  engages the stop structure  177 A of the mount support  166  for stopping the sliding part  168  as shown in  FIG.  24   . 
     Referring to  FIGS.  2  and  25   , while the bottom part  104  remains in a lowered position relative to the head rail  102 , the operating member  164  of the control module  140  can be operated for lowering the intermediate rail  106 . As a result, the rotary axle  136  rotates in a direction that causes the sliding part  172  to concurrently rotate about the rotation axis  144  and slide on the rotary axle  136  in the direction A 1 . As the sliding part  172  slides in the direction A 1 , the sliding part  172  can travel inside the channel  168 N of the sliding part  168 . Once the intermediate rail  106  reaches a desired position, the user can release the operating member  164  of the control module  140 , and the sliding part  172  can accordingly stop moving. In case the intermediate rail  106  is lowered to a lowest position adjacent to the bottom part  104 , the sliding part  172  can slide in the direction A 1  until the protrusion  172 B of the sliding part  172  engages the protrusion  168 B of the sliding part  168  for stopping the sliding part  172 , as shown in  FIG.  25   . Like the previous embodiments, the limiting mechanism  142  shown in  FIGS.  21 - 25    can prevent undesirable upward displacement of the intermediate rail  106  caused by a rise of the bottom part  104 . 
     Advantages of the structures described herein include the ability to provide a window shade that has an actuating system operable to independently displace a bottom part and an intermediate rail for setting the window shade to a desired configuration. Moreover, the actuating system can have a limiting mechanism that can prevent undesirable upward displacement of the intermediate rail caused by a rise of the bottom part and undesirable downward displacement of the bottom part caused by a downward displacement of the intermediate rail. Therefore undesirable interaction between the bottom part and the intermediate rail can be prevented during operation, which may ensure reliable operation of the control modules respectively coupled to the bottom part and the intermediate rail. 
     Realizations of the structures have been described only in the context of particular embodiments. These embodiments are meant to be illustrative and not limiting. Many variations, modifications, additions, and improvements are possible. Accordingly, plural instances may be provided for components described herein as a single instance. Structures and functionality presented as discrete components in the exemplary configurations may be implemented as a combined structure or component. These and other variations, modifications, additions, and improvements may fall within the scope of the claims that follow.