Patent Abstract:
The present invention relates to a self-raising window covering and a control mechanism for the window covering. In particular, the window covering includes a drive unit, such as constant force spring, that is adapted to apply a substantially constant rotational force on the drive axle. A cord winding assembly is coaxially mounted on the drive axle, and includes at least one winding drum operatively connected to a second end of the raising cord and having a tapered portion, as well as a rotatable positioning member for moving the cord winding assembly laterally along the drive axle upon rotation of the positioning member. The cord winding assembly is adapted to translate the rotational force on the drive axle to a raising force on the raising cord, wherein the raising force is greater than a downward force exerted by the shade element and bottom rail throughout the range of opening and closing. A clutch member or locking member is also operatively connected with the axle and adapted to releasably lock the drive axle in a desired position.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. patent application Ser. No. 11/880,000, filed on Jul. 19, 2007, which is incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to a window covering that may be raised without the need to apply a force to either a control mechanism or the window covering itself as the window covering is opened. In particular, the present invention relates to a window covering having a control mechanism configured to exert an upward force on the light blocking element and bottom element that is of sufficient magnitude to raise the light blocking element and bottom rail without additional force being applied by the user during raising. The control mechanism selectively raises the window bottom element and portions of the window covering, and may be actuated by a downward force applied to the bottom element by the user. 
       BACKGROUND OF THE INVENTION 
       [0003]    Window shades and coverings are found in many applications and used to regulate the amount of light entering a room, and to provide aesthetic appeal to a decor. Such window shades and coverings take many forms, including roller shades, Roman shades, Venetian blinds, and cellular shades. Conventional cellular or pleated shades utilize cord locks or a transmission mechanism to raise, lower and position the window covering in a desired position. With window coverings utilizing a cord lock, cords run up through the folded fabric, across the inside of a head rail and exit through a locking mechanism. Other cellular shades include a transmission mechanism and a continuous loop cord that is pulled by a user to raise and lower the window shade. Roman shades and Venetian blinds also tend to include raising cords that are secured to a lower bar or bottom rail. 
         [0004]    There are some disadvantages to these designs. Cords present the potential hazard of a child getting caught in or strangled by the exposed control cord. Cords also tend to distract from the aesthetics of a window covering in that they extend along the face of the window covering and, when the window shade is opened, must either be wrapped on a hook or just left on the floor. With window coverings that utilize cord locks, the cords also experience substantial wear due to friction against surfaces as a result of raising and lowering of the window covering. 
         [0005]    Other window coverings include common roller shades, which operate in the absence of a cord. These roller shades include a wound torsion-spring retraction mechanism in combination with a clutch or locking mechanism mounted with a roller onto which the shade is rolled and collected. In operation, a roller shade is pulled down by a user to a desired location, where it is locked in place by the clutch or locking mechanism. To unlock and release the shade so that it may be raised, the user typically pulls on a bottom rail of the shade, extending the shade sufficiently to disengage the internal clutch or locking mechanism within. When the clutch or locking mechanism is disengaged and the user releases the shade, the shade is retracted using the torsion-spring driven retraction mechanism. Known roller shades, however, are only operable with flat shade material which rolls up neatly into a confined location. 
         [0006]    The mechanism utilized in such roller shades is not compatible with other window coverings, such as cellular shades, Venetian blinds, and Roman shades. As roller shades are raised, the amount of shade being lifted decreases such that a constant force torsional spring member is capable of applying the necessary winding or upward force throughout the opening range. By contrast, a similar lifting mechanism is typically unsuitable in cellular shades, Venetian blinds, and Roman shades. In these types of window coverings the light blocking material is typically gathered by raising a bottom member, such as a bottom rail, and increasing amounts of weight are gathered on the bottom member as the window covering is raised. The reason for this is that the shade material or light blocking element increasingly stacks on the bottom rail as the bottom rail rises, which increases the load on the lifting mechanism. 
         [0007]    In order to address this increasing weight, very strong torsional springs have been used to accommodate the maximum weight of the shade. One drawback to this approach, however, is that the rate at which the window covering is retracted may be too fast and uncontrolled. One attempt to address this problem is found in U.S. Pat. No. 6,666,252, issued to Welfonder. This patent teaches the use of a fluid brake to control the rate at which the raising cords are retracted throughout the raising process. Another approach that has been used is shown in U.S. Pat. No. 6,056,036, issued to Todd, which employs a mechanical friction member to continuously slow the rate of retraction. One problem with these approaches has been that the spring utilized exerts a force that is difficult for a user to overcome when attempting to lower the shade. Excessive pulling force by the user often results in damage to the window covering. 
         [0008]    Alternatively, variable force springs have been used. Such variable force springs are substantially more complicated in use and manufacture. 
         [0009]    Therefore, there is a need for a window covering raising mechanism for window coverings such as Venetian blinds, cellular shades and Roman shades that is self-raising and overcomes the foregoing problems. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention relates to a self-raising window covering and a control mechanism for the window covering. In particular, the window covering is a self-raising window covering that includes a head rail, a light blocking element, such as a cellular panel, blind slats, or Roman shade material, a bottom rail or bottom element, at least one raising cord operatively connected at a first end to the bottom rail or bottom element, and a control mechanism. The head rail may define an elongated channel wherein the control mechanism is disposed therein. In some embodiments, the control mechanism includes a drive shaft and a drive unit operatively connected with the drive shaft. The drive unit, which may be a constant force spring, is adapted to provide a substantially constant rotational force on the drive shaft. 
         [0011]    At least one translation member is also provided in co-axial relation with the drive shaft. Typically, the number of translation members will be the same as the number of raising cords. However, in some instances, the translation member may be adapted to raised multiple cords. The translation member preferably includes at least one winding drum operatively connected to a second end of the raising cord and having a tapered portion. The translation member also includes a rotatable positioning member for moving the translation member laterally along the drive shaft upon rotation of the positioning member. In a preferred embodiment, the positioning member is a threaded tubular member connected to the winding drum. The translation member is adapted to translate the rotational force on the drive shaft to a raising force on the raising cord, wherein the raising force is greater than a downward force exerted by the light blocking element and bottom rail throughout the range of opening and closing. In a preferred embodiment, the translation member is rotationally secured with the drive shaft by a hub member adapted to engage the translation member and the drive shaft. The hub member may be in a sliding relationship with the tapered portion of the translation member. 
         [0012]    A clutch or locking or actuating member is also operatively connected with the axle and adapted to releasably lock the drive shaft in a desired position. In a preferred embodiment, the clutch or locking or actuating member comprises a spring member adapted to releasably secure the position of the drive shaft when in a tightened condition and to permit rotation of the drive shaft when in a relaxed condition. A reciprocator may also be disposed annularly about the drive shaft and adapted to selectively hold the spring member in the tightened and relaxed positions. An annular collar may also be secured with the drive shaft and connected with the spring member. In some embodiments, it may also be desired to include a brake unit engageable with the translation member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view, partly in cutaway, of a preferred embodiment of a window covering according to the present invention; 
           [0014]      FIG. 2  is a exploded perspective view of the single spring coil drive unit of  FIG. 1 ; 
           [0015]      FIG. 3  is a side elevational cross section view of the single spring coil drive unit of  FIG. 1 ; 
           [0016]      FIG. 4  is a side elevational cross section view of an alternative single spring coil drive unit; 
           [0017]      FIG. 5  is a side elevational cross section view of a double spring drive unit; 
           [0018]      FIG. 6  is a side elevational cross section view of an alternative double spring drive unit; 
           [0019]      FIG. 7  is an exploded perspective view of the translation member of  FIG. 1 ; 
           [0020]      FIG. 8A  is a front elevational view of the window covering of  FIG. 1  in a closed position and with the head rail in cross section; 
           [0021]      FIG. 8B  is a front elevational view of the window covering of  FIG. 1  in a partially open position and with the head rail in cross section; 
           [0022]      FIG. 9A  is a perspective view of a preferred clutch member when the window covering is in a fully raised position; 
           [0023]      FIG. 9B  is a cross sectional view of the clutch member of  FIG. 9A ; 
           [0024]      FIG. 10A  is a perspective view of the clutch member of  FIG. 9A  as the user pulls down on the window covering; 
           [0025]      FIG. 10B  is a cross sectional view of the clutch member of  FIG. 10A ; 
           [0026]      FIG. 11A  is a perspective view of the clutch member of  FIG. 9A  as the user releases the window covering; 
           [0027]      FIG. 11B  is a cross sectional view of the clutch member of  FIG. 11A ; 
           [0028]      FIG. 12A  is a perspective view of the clutch member of  FIG. 9A  as the user pulls down on the window covering to release the clutch member; 
           [0029]      FIG. 12B  is a cross sectional view of the clutch member of  FIG. 12A ; 
           [0030]      FIG. 13A  is a perspective view of the clutch member of  FIG. 9A  as the window covering self-raises; 
           [0031]      FIG. 13B  is a cross sectional view of the clutch member of  FIG. 13A ; 
           [0032]      FIG. 14  is a perspective view of an alterative embodiment of a window covering according to the present invention with a deceleration member; 
           [0033]      FIG. 15A  is a side elevational cross section view of the deceleration member of  FIG. 14  disengaged from the translation member; 
           [0034]      FIG. 15B  is a side elevational cross section view of the deceleration member of  FIG. 14  engaging the translation member; and 
           [0035]      FIG. 15C  is a side elevational cross section view of the deceleration member of  FIG. 14  when the window covering is fully raised. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0036]    The invention disclosed herein is susceptible to embodiment in many different forms. Shown in the drawings and described in detail hereinbelow are preferred embodiments of the present invention. The present disclosure, however, is only an exemplification of the principles and features of the invention, and does not limit the invention to the illustrated embodiments. 
         [0037]    Referring to  FIG. 1 , an embodiment of a self-raising window covering  10  according to the present invention is shown. A head rail  12  defining a channel is provided. A pair of drive units, such as spring units  14  and  16  are coaxially mounted about a drive axle  18 . Also mounted on drive axle  16  are translation members  20  and  22 . Each of translation members  20  and  22  includes a frustoconical winding drum  24  and  26 , respectively. Raising cords  28  and  30 , which are shown as wound on winding drums  24  and  26 , are secured at an end to the winding drums  24  and  26 . Each of the translation members  20  and  22  further comprise a threaded tubular member  32 ,  34 . In this embodiment, a clutch or actuator  36  is also provided and co-axially mounted on the drive axle  18 . Each of these components is discussed in greater detail below. Window covering  10  further includes a light blocking element, such as cellular shade material  38  and a bottom member, such as bottom rail  40 . A relatively short length of cord  42  is also provided so that the user can pull down the window covering and, as will be discussed in further detail, release the clutch so that the window covering will retract itself. 
         [0038]    Referring to  FIG. 2 , a preferred embodiment of the spring unit  14  is shown. The spring unit  14  comprises a spring casing  42 , a spring axle  44 , a constant force coil spring  46  and a cover  48 . The coil spring  46  is secured with the spring axle  44 , and is secured within the casing  42  and cover  48 . With coil spring  46 , a first end  50  of the spring  46  is secured to the spring axle  44 , which is mounted on the drive axle  18  ( FIG. 1 ). In this preferred embodiment, the coil spring provides sufficient rotational force to the drive axle and winding drums to raise the light blocking element and bottom rail. Other alternative embodiments of suitable spring units are shown in  FIGS. 3-6 . 
         [0039]    For example, a spring unit  114  is shown in  FIG. 3  as including a spring axle  144  and a spring member  146 . The spring axle  144  is offset from the drive axle  118 . A first end  150  of the spring member  146  is secured with the spring axle  144  and a second end  152  is secured with the drive axle  118  to impart a rotational force thereon. Another example of a suitable spring unit is shown in  FIG. 4  as spring unit  214 . This example is similar to the embodiment shown in  FIG. 3  except that no spring axle is provided. Instead, a portion of spring member  246  coils about itself and an end  252  of the spring member  246  is secured to the drive axle  218 . Still other suitable embodiments of spring units are shown in  FIGS. 5 and 6 . In  FIG. 5 , spring unit  314  includes a double spring coil member  346  which is secured to a drive axle  318  and to spring axles  344  and  345 . In  FIG. 6 , a double spring coil member  446  is connected to drive axle  418 , but does not include spring axles. Although each of the embodiments shown utilize a spring as the driving mechanism for the drive unit, it should be understood that any suitable mechanism for imparting a rotational force on a drive axle may be utilized. 
         [0040]    Referring again to  FIG. 1 , the rotational force exerted upon a drive axle  18  causes the raising of the light blocking  38  by way of translation member  20  and  22 . Further details on a preferred embodiment of a translation member is provided with reference to  FIG. 7 . 
         [0041]    Translation member  20  is mounted co-axially with the drive shaft (not shown), and includes a winding drum  24  and a rotational positioning member, such as threaded tubular member  32 . The translation member  20  is preferably mounted to the drive axle by way of a hub member, such as adapter  60 . The winding drum  24  may be tapered and is preferably frustoconical in shape, and may include striations or grooves. An end of the raising cord (not shown) is secured towards the larger diameter end  62  of the winding drum  24  such that as the cord is wound, the raising cord is wrapped around increasingly narrower portions of the winding drum  24 . The translation member is mounted within the head rail  12  ( FIG. 1 ) by way of frame  64 , which includes rollers  66 . Rollers  66  engage threaded tubular member  32 , and are held in position by bracket  68 . 
         [0042]    Referring to  FIGS. 8A and 8B , the raising of the window covering is shown. When the window covering is fully closed, as shown in  FIG. 8A , the raising cord  28  is fully extended and connected to the winding drum  24  at a wider portion thereof. As the bottom rail rises, the threaded tubular member  32  causes the translation member to move laterally within the head rail  12  such that the raising cord extends substantially straight down from the winding drum  24 , as shown in  FIG. 8B . 
         [0043]    As the spring units  14  and  16  raise the bottom rail  40  and stack the light blocking element  38  on the bottom rail  40 , the total weight being raised increases. The load of the springs is described with reference to one of the spring units. The load of the spring unit  14  can be approximated as the force F relative to the drive axle as being equal to the product of the suspended weight W, which includes the weight of the bottom rail plus the amount of panel stacked thereon, by a winding radius R of the winding drum  24 . As the bottom rail rises, W increases while R decreases. Because of the tapered winding drum  24 , the force of the spring unit  14  translated to an upward force on the raising cord  28  will vary slightly so that the constant force spring  46  ( FIG. 2 ) can fully raise the bottom rail  40  and light blocking element  38 . In order to lower the window covering, a user exerts an approximately constant pulling force regardless of the position in height of the window covering. When the window covering is raised, the total weight stacked on the bottom rail is at its maximum. As the user pulls down on the bottom rail  40  or cord  42 , the contribution to the force needed to overcome the upward force of the spring units  14  and  16  from the weight of the bottom rail  40  and light blocking element  38  decreases. However, the effective pulling force is increased due to the greater moment arm. As such, the user does not need to exert as much force as would be required with a cylindrical winding drum. 
         [0044]    As discussed, the drive units are configured to provide a force sufficient to raise the bottom rail  40  and light blocking element  38  regardless of the current position of the window covering. Accordingly, a clutch member or actuator  36  is also provided in order to lock the window covering in a desired position. Clutch member  36  is mounted with the drive axle  18  and is configured to unlock the drive axle  18  as the user pulls down the bottom rail  40 , and to lock the drive axle  18  when the user releases the bottom rail  40  at the desired height. When the user pulls down slightly on the bottom rail again, the clutch disengages and allows the bottom rail  40  to be raised by the spring units  14  and  16 . Referring to  FIGS. 9A and 9B , the clutch member  36  includes a casing  70  with protrusions  72  and  74  projecting therefrom. A collar  76  rotating with the drive axle  18  is provided, which reciprocates axially along the drive axle  18 . A reciprocator  78  is co-axially mounted over collar  76  and is movable both rotatably and axially therewith. A spring  80  having a first end  82  and a second end  84  is provided between collar  76  and reciprocator  78 . 
         [0045]      FIGS. 9A and 9B  show the clutch  76  when the window covering  10  is in a fully raised position. Spring  80  is in a relaxed condition with second end  84  in an abutting relationship with protrusion  74 . As shown in  FIGS. 10A and 10B , when the user pulls on the bottom rail (not shown), a clockwise rotation (as shown) of the axle  18  and the collar  76  occurs and causes the second end  84  of the spring  80  to disengage from protrusion  74 . Spring  80  tightens on collar  76  such that rotation of the collar  76  brings reciprocator  78  into abutment with protrusion  72  through contact at second end  84  of the spring  80 . As the reciprocator  78  abuts against protrusion  72 , the spring  80  relaxes again such that drive axle  18  may continue to rotate as the user pulls on the bottom rail. Referring to  FIG. 11A and 11B , as the user releases the bottom rail at a desired height, spring  80  again tightens on collar  76 . The drive axle  18 , as urged by the spring units  14  and  16  ( FIG. 1 ), rotates receiprocator  78  in a counterclockwise direction to a locking position. In this locking position, the spring  80  tightens to stop rotation of the drive axle  18 . Referring to  FIGS. 12A and 12B , as the user pulls down slightly on the bottom rail, a resulting clockwise rotation of the drive axle  18  and collar  76  causes the reciprocator  78  to disengage from the locking position. When the user releases the bottom rail as shown in  FIGS. 13A and 13B , the spring units  14  and  16  cause the drive axle  18  to rotate in a counterclockwise direction to bring second end  84  of the spring  80  into engagement with protrusion  74 , and thereby loosening spring  80 , which permits drive axle  18  to continue rotating and fully opening the window covering. 
         [0046]    An alternative embodiment of the window covering according to the present invention is shown in  FIG. 14 . In most respects, this embodiment is the same as the ones previously discussed. Window covering  510  includes a head rail  512  having a pair of spring units  514  and  516  mounted with a drive axle  518  mounted therein. Translation members  520  and  522  are also provided. Raising cords  528  and  530  pass through light blocking element  538  and are connected with bottom rail  540 . In addition, a deceleration member  550  is provided. Deceleration members  550  is engageable with the translation member  522  to slow down the rise of the bottom rail as it approaches the head rail. 
         [0047]    The preferred embodiment of the deceleration member  520  is shown in  FIGS. 15A-15C . In the position of  FIG. 15A , the translation member is disengaged from the deceleration member  550 . As the winding cord  526  is wound on winding drum  24 , the translation member  522  moves towards the deceleration member  550 . As the translation member engages with the deceleration member  550  as shown in  FIG. 15B , the rotation of the winding drum  526  causes a plate  552  of the deceleration member to rotate. The plate  552  is operative connected to an axle sleeve  554 . Axle sleeve  554  is in contact with an oil liquid contained inside a housing  556  and is configured to provide rotational movement resistance within the oil liquid. For example, protrusions or fins may be provided on the axle sleeve  554 . The rate at which the bottom rail is raised by the spring units  514  and  516  is slowed as the bottom rail reaches the head rail so that the bottom rail more smoothly stops at a fully opened position. 
         [0048]    The foregoing descriptions are to be taken as illustrative, but not limiting. Still other variants within the spirit and scope of the present invention will readily present themselves to those skilled in the art.

Technology Classification (CPC): 4