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You are an expert at summarizing long articles. Proceed to summarize the following text: 
[0001]    The present application is a Continuation-In-Part of an earlier application Ser. No. 12/564,806, filing date Sep. 22, 2009, by the same inventors, and incorporate the prior disclosure of the earlier application, with additional disclosure of new matters introduced and claimed herein. 
     
    
     FIELD AND BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to window curtain containing Roman shade, using a controllable refraction device for up-down release/retract of the Roman shade. 
         [0003]    Window curtains are made for functional usages of blocking sunlight, or creating privacy space, and for decorative purpose of adding visual attractiveness to households. Depending on consumer likings and preferences, quite a number of styles and variation of window curtains/shades are commercially available. Traditional fabric curtains, plastic or wood mini-blinds, Roman shades, vertical blinds, etc, are all the commonly seen choices. 
         [0004]    Present invention provides a roller-shade based Roman shade, where the pull-up and extend-down setting between the front surface (the fold-accordion side of the Roman shade) and the rolling spool screen can have different steps, resulting in the “opaqueness” of the complete curtain to be within consumer&#39;s control. 
         [0005]    The multi-step engagement mechanism of present application can be applied to either a fix-string type traditional Roman shade, or a more modern “cordless” type of Roman shade with a roller spool serving as the pull-down and retracting-up control. 
         [0006]    The description of present invention is based upon a “cordless” type Roman shade having a roller spool in the back side. However, it should be understood that the traditional “corded” type Roman shade can equally benefit from the multi-step construction of present application. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0007]    Present invention teaches to make a Roman shade window curtain where a retraction device (a rolling spool) is used at the back side to retract/unfold the shade, and there are multiple places of engagement between the bottom point of the rolling spool screen and the front fabric. 
         [0008]    As such, consumers have the choice of controlling the total thickness of a window curtain, by setting the different bottom position of the roller spool screen relative to the front fabric screen, creating a user-oriented “day-and-night” selections, where the bottom position is engaged to the bottom portion of the front Roman shade fabric, very least amount of light would be allowed, whereas if the bottom position of the rolling spool screen is engaged to the upper portion of the front Roman shade fabric, the overall opaqueness of the window shade will be reduced and allowing more light to come in. 
         [0009]    The description of present invention is based upon a “cordless” type Roman shade having a roller spool in the back side. However, it should be understood that the traditional “corded” type Roman shade can equally benefit from the multi-step construction of present application. And the disclosure and claimed scope of present application is thus not limited to the “cordless” construction. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the preferred embodiments of the invention and together with the description, serve to explain the principles of the invention. 
           [0011]    A brief description of the drawings is as follows: 
           [0012]      FIG. 1  shows an overall operation view of the sliding and locking mechanism, when the two sliding tubes are not placed towards the two sides, allowing the rolling spool to travel up and down, until a desired point is reached where the sliding tubes can be moved to two sides and to engage the bottom beam to the desired vertical points on the Roman shade fabric. 
           [0013]      FIG. 2  shows the sliding tubes moved to the sides and engaging the auxiliary rods, allowing the rolling spool to retract the whole window curtain up, at the point of engagement. 
           [0014]      FIG. 3  shows the connection between the Roman shade (the accordion wavy formation on the front fabric) and the rolling spool curtain, where the rolling spool curtain can move up and down in the gap created between the auxiliary rod and the delineating rod at each of the fold lines. 
           [0015]      FIG. 4  provides a side view of the rolling spool curtain engaged to the front Roman shade fabric. 
           [0016]      FIG. 5  shows the structure of bottom beam, where the rigid piece is wrapped inside a round tube. 
           [0017]      FIG. 6  shows the detailed structure of the bottom beam, with side view shown in  FIG. 6   b.    
           [0018]      FIG. 7  shows the assembly parts of rigid piece, round tube and sliding tube. 
           [0019]      FIG. 8  shows the assembly parts of round tube and sliding tube.  8   a  shows the sliding tube, with an inside ridge shown by dotted line, which will be assembled into the bottom opening of round tube. Both round tube and sliding tube has congruent top openings, to accommodate the connection between the rigid piece to the lower end of rolling spool curtain, as shown in  8   c.    
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    As shown herein, the Roman curtain  20  of present invention consists primarily of a front side Roman shade  40  (i.e. the shade made to have a accordion wavy style that people see) and a back side rolling spool screen  52 . 
         [0021]    Said rolling spool screen  52  can be extended down from and be retracted back up into a rolling spool  50  which is located inside a head rail, or mounted to the head rail in the event that a piece of wood or other material is used as a head rail to reduce cost. The rolling spool  50  and the connection of the Roman shade along with the rolling spool screen to the head rail is disclosed in the inventor&#39;s prior disclosure, other than helping to explain the novelty points of present application, do not form the claimed invention of present application and need no further disclosure herein. 
         [0022]    Front side Roman shade  40  forms the resulting wavy Roman shade where the fold lines serve as the places for the “waves” to be formed, when the curtain  20  is pulled up. 
         [0023]    Each fold line is shown by a position-delineating device  42  where a delineating rod  421  clips a horizontal segment of the shade  40  into a horizontal fold line, which is then attached to a corresponding auxiliary rod  425  by a double-pronged hook  422 . 
         [0024]    See  FIG. 3  for the structural implementation of the horizontal fold line formed on the Roman shade surface. 
         [0025]    Auxiliary rod  425  does not go the full length from one side of the curtain  20  to the other side. Only partial length is needed for auxiliary rod  425  to serve as an “engaging” point for the sliding tube  565  (explained later) to get wedged to. The middle portion along the horizontal linear direction of the pair of auxiliary rod  425  provides for the room to allow the bottom beam  560  to go up and down as user desired, for purpose of setting the desired thickness (combining 2 layers of fabric from the Roman shade in the front and the rolling spool screen in the back) of a window curtain 
         [0026]    A horizontal trough  420  is formed on said position-delineating rod  421 , for receiving a small portion of fabric curtain  41  and getting that small horizontal stretch of the fabric curtain  41  tucked into the trough  420 . Said double-pronged hook  422  has a first open trough  423  and second open trough  424 , located opposite of each other, so that when they are used at the two ends (left and right ends) of delineating rod  421 , with the first open trough  423  clamping to the delineating rod  421 . 
         [0027]    The pair of second open troughs  424  (on the double-pronged hooks  422 ) similarly clamp the auxiliary rod  425 , forming a gap  426  (between auxiliary rod  425  and delineating rod  421 ) allowing rolling spool screen  52  to travel up and down as desired. 
         [0028]    On  FIG. 3 , the same mechanical structure for a second (and lower) fold line of delineating device  44 , with parts number of  441 ,  442 ,  443  and  444 , etc., work in the same way as the  42  delineating device and requires no more disclosure herein. 
         [0029]    Auxiliary rod  425  is a partial length rigid structure that goes from the two sides of the curtain  20  towards the middle, as shown in the figures. As such, the rolling spool screen  52  is placed inside the gap  426  created between the delineating rod  421  and auxiliary rod  425 , while the auxiliary rod  425  is connected to the delineating rod  421  by the two double-pronged hook  422  on the two sides of the curtain  20 . 
         [0030]    The front shade  40  has its top affixed to a horizontal head rail  5 , so that the fabric  41  would naturally drape down. 
         [0031]    Inside head rail  5 , there is a rolling spool  50 , used to provide the up-down movements of the rolling spool screen  52 . 
         [0032]    A bottom beam  560  horizontally forms the low-end of said rolling spool screen  52 . 
         [0033]    Referring to  FIGS. 5 and 6 , the bottom beam  560  is made up of a horizontal rigid tab piece  561  and a round tube  562  with a top opening  563  to accommodate the connection from the rigid tab piece  561  to the lower end of the rolling spool screen  52 . 
         [0034]    The external diameter size of the bottom beam  560  will be such that it is slightly smaller than the gap  426  formed between auxiliary rod  425  and delineating rod  421 , allowing bottom beam  560  to travel through the gap  426  (unless the sliding tubes  565  are pushed to two sides) up and down, for purpose of choosing the desired point of engaging the bottom beam  560  to a selected fold line of the Roman shade  40 . 
         [0035]    Said rigid piece  561 , when viewed from the side, appeared to have a semi-hook structure, as shown in  FIG. 6   b . The round tube  562 , as shown in  FIG. 6   b , has a bottom opening  564 , for purpose of receiving a sliding tube  565 , as explained later. 
         [0036]    Two sliding locking tubes  565  are placed around the outside surface of round tube  562 , allowing the sliding motion of the tubes  565  to go from the two ends (shown as blackened pieces) in  FIG. 2(   iv ) to the location towards the middle of the bottom beam  560  (shown as blackened pieces) in  FIG. 1  ( iv ). 
         [0037]    The locking tubes  565 , as shown in  FIG. 8   a , has a top opening  593  along the length of the tube body and an inside ridge  594  (shown as dotted line, since it is actually not visible when looking at it from the outside of the locking tube  565 ), so that locking tubes  565  are placed snugly on the outside of round tube  562 . 
         [0038]      FIG. 8   b  shows the round tube  562 . 
         [0039]      FIG. 8   c  shows locking tube  565  having been placed around the outside of round tube  562 , with the inside ridge  594  slidably wedged into the bottom opening  565 , allowing the sliding motion of locking tube  565  relative to the round tube  562 . 
         [0040]    The top opening  593  is aligned with the top opening  563  of the round tube  562 , to accommodate the connection of rolling spool screen to the rigid piece  561  of the bottom beam  560 . 
         [0041]    When the locking tubes  565  are kept at the left and right extremities of the bottom beam  560 , the rolling spool  50  will be able to roll up the fabric curtain  41  of the roman shade  40 , at the point where the locking tubes  565  wedged into the gap  426  between the delineating rod  421  and auxiliary rod  425 . 
         [0042]    The size (referring to external diameter of locking tube  565 ) will be made to be bigger than the gap  426 , so that when said locking tubes  565  are pushed to the left and right side extremities of the bottom beam  560 , they will get wedged into gap  426 , instead of going through the gap. 
         [0043]    When the locking tubes  565  are slid towards the middle of the bottom beam  560 , the rolling spool  50  and screen  52  can then move up and down, independent of the fabric curtain  41 , due to the fact that the rolling spool  50  is “disengaged” from the fabric curtain  41  of the Roman shade. 
         [0044]    Consequently, there will be the ability for the multi-step control of the location where the rolling spool screen  52  can be ‘engaged’ to the fabric screen  41 , for purpose of controlling how much fabric curtain is left below the point of the bottom beam  560 .

Summary:
Present invention teaches to make a Roman shade window curtain where a sliding locking mechanism is provided at the bottom beam of the rolling spool at the back side of the Roman shade, where the engaging positions between the rolling spool bottom beam and the pair of auxiliary rods can be set according to user preference, by sliding the locking tubes towards the middle to move the engaging point up and down, and by sliding the licking tubes to the left and right extremities for engaging the bottom to the desired fold line on the Roman shade.