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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/189,597, filed Jul. 7, 2015, entitled “DRUM CABLE DRIVE SYSTEM FOR SLIDING WINDOW SASH,” the disclosure of which is hereby incorporated by reference herein in its entirety. 
     
    
     INTRODUCTION 
       [0002]    Powered window systems may include a motor-driven cross shaft installed under a sill of the window which drives a loop of chain in both of the side pockets of the window. Such a system uses a sprocket aligned with the pocket on both sides. Another system type includes a motor-driven lead screw mounted on one side of the window. The lead screw drives a nut coupled to a linear bearing to which an arm is attached. The arm reaches to the middle of the check rail to apply the force to open the window. Both such systems suffer from high frictional forces and are often bulky, thus limiting their application. 
       SUMMARY 
       [0003]    In one aspect, the technology relates to: a system having: an operator; a drive shaft configured to rotate based on a rotation of the operator; a threaded drum translatably disposed on the drive shaft; and a cable wrapped about the threaded drum, such that a rotation of the drive shaft simultaneously (a) wraps a first portion of the cable about the threaded drum and (b) unwraps a second portion of the cable from the threaded drum. In an embodiment, an end of the first portion of the cable is connected to the threaded drum, and wherein an end of the second portion of the cable is connected to the threaded drum. In another embodiment, the system further includes a housing, wherein the threaded drum is disposed within the housing. In yet another embodiment, the system further includes a projection extending from the housing at least partially into the threaded drum, wherein the projection is fixed relative to the threaded drum. In still another embodiment, the projection extends from an interior of the housing. 
         [0004]    In another embodiment of the above aspect, the system further includes a plurality of alignment rollers configured to align the cable with a plurality of threads of the threaded drum. In an embodiment, the housing includes a first portion and a second portion detachably secured to the first portion, wherein the first portion and the second portion are both aligned substantially axially with the threaded drum. In another embodiment, the operator has a hand-crank. In yet another embodiment, the operator has a motor. In yet another embodiment, the system further includes an angular adapter connected to the operator and the drive shaft, wherein the operator and the drive shaft are not coaxial. 
         [0005]    In another aspect, the technology relates to a system having: a drive shaft includes an axis; a threaded drum translatably disposed along the axis; and a cable system at least partially disposed about the threaded drum, wherein the cable system is configured to be simultaneously payed out from the threaded drum and wrapped about the threaded drum, during a rotation of the threaded drum. In an embodiment, a first end of the cable system is payed out from the threaded drum while the second end of the cable system is wrapped about the threaded drum. In another embodiment, the cable system includes a first cable and a second cable. In yet another embodiment, the system further includes a bearing disposed at both ends of the drive shaft, wherein the drive shaft is rotatably engaged with the bearings. In still another embodiment, the system further includes a projection extending at least partially into the threaded drum, wherein the projection is fixed relative to the threaded drum. 
         [0006]    In another embodiment of the above aspect, the system further includes a base, wherein the projection and the bearings are connected to the base. In an embodiment, the system further includes a cover connected to the base. In another embodiment, the cable system is secured to the threaded drum at both ends of the cable system. In still another embodiment, the system further includes an operator. In another embodiment, the operator is at least one of a motor and a hand-crank. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    There are shown in the drawings, embodiments which are presently preferred, it being understood, however, that the technology is not limited to the precise arrangements and instrumentalities shown. 
           [0008]      FIG. 1A  depicts a front perspective view of a drive mechanism for a window. 
           [0009]      FIG. 1B  depicts a rear perspective view of the drive mechanism of  FIG. 1A . 
           [0010]      FIG. 2  depicts an exploded perspective view of the drive mechanism of  FIG. 1A . 
           [0011]      FIG. 3  depicts a schematic perspective view of corner bracket pulley system utilized in a drum drive system for a window. 
           [0012]      FIG. 4  depicts a roller support utilized in a drum drive system for a window. 
           [0013]      FIG. 5  depicts a schematic view of a drum drive system for a window. 
           [0014]      FIG. 6  depicts another schematic view of a drum drive system for a window. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The drive mechanisms, as well as the drum drive systems that incorporate such mechanisms, described herein can fit into a slender space and provide long travel cord or cable travel. A thin cord or cable can pass through very small pathways so the mechanism can be hidden inside a standard window frame, for example, at the top or bottom of the frame. In other examples, the drive mechanism may be installed on an exterior of the window frame, so as to be utilized in retrofit configurations. The cord loop allows a window sash to be lifted and lowered, or slid horizontally in certain applications, to force the movement of the sash overcoming friction or gravity as needed. In a single- or double-hung window, the cord loop passing through the head and both jambs allows attachment to both sides of the sash. This allows the sash to remain square in the frame throughout the travel. The drive mechanism may be used in windows that utilize balances or those that do not utilize balances. Examples of additional components used in conjunction with the drive mechanism, so as to produce a complete drive system, are also depicted below. 
         [0016]      FIG. 1  depicts a perspective view of a drive mechanism  100  for a window, while  FIG. 2  depicts an exploded perspective view of the drive mechanism  100 .  FIGS. 1 and 2  are described concurrently. The drive mechanism  100  includes a housing  102  that includes a base portion  102   a  and a cover portion  102   b . The base portion  102   a  is substantially elongate and includes an axis A defined by a U-shaped channel  114 . In another example, the axis A may be defined by two receivers present on bearings disposed at each end of the base portion  102   a . In such a case, the receivers would be configured to receive a drive shaft. In the depicted example, however, a drive shaft  108  is unsupported at both ends. A square drive shaft  108  is depicted, although other cross-sectional shapes are contemplated. The base portion  102   a  also defines one or more openings  110 , through which one or more cables are routed to raise and lower an associated window sash (as described below). The base portion  102   a  also includes a projection or spline  112  extending from the U-shaped channel  114  of the base portion  102   a . The projection  112  is configured to be disposed within threads  116  of a drum  118 , when that drum  118  is received on the drive shaft  108 . The drum  118  may define an axial opening  120  that is shaped to mate with the drive shaft  108 . In the depicted example of a square drive shaft  108 , the corresponding square axial opening  120  engages with the drive shaft  108 , such that the drum  118  rotates due to a corresponding rotation of the drive shaft  108 . In other examples, round drive shafts and axial openings may be utilized, with a locking set screw, for example, used to engage the drive shaft and the drum. Regardless, when the drum  118  is disposed on the drive shaft  108  and the drum  118  is received in the U-shaped channel  114 , the drive shaft  108  and drum  118  are axially aligned with axis A. A cover portion  102   b  may be clipped onto one or more splines  122  on the base portion  102   b , so as to protect the drum  118  and cable (not shown) from dirt and other contaminants. 
         [0017]    An end cap  124  may be secured to one end of the housing  102  so as to further limit intrusion of contaminants as well as provide an abutment against which the drive shaft may rotate. In this case, the end cap  124  includes a male projection  126  that mates with a female recess  128  in the base portion  102   a . Disposed at an opposite end of the base portion  102   a  in the depicted embodiment is an angular adapter  130 . The adapter  130  may be formed in two halves and also includes a male projection  132  that mates with a female recess  134  in the base portion  102   a . An angled gear system  104  is disposed in the adapter  130 , so as to transfer rotational motion of one shaft  136  to that of another shaft  138 , which ultimately drives the drive shaft  108 . Thus, an operator may be offset from the axis A and still operate the drive mechanism  100 . Different operators may be used, for example, a motor or a hand crank. In another example, the motor may also include a hand crank, should the window need to be operated in the event of a power outage. The motor may be powered by building power, solar power, battery power, and so on. In other examples, the operator (motorized or manual) may be aligned with the axis A, as required or desired for a particular application. In applications where the drive mechanism is disposed within the window frame or otherwise hidden, a motor aligned with the axis A may be particularly desirable to conserve space. 
         [0018]    A cord or cable system (not shown) is routed through or along the window frame and connected to the window (certain example cable routing configurations are depicted below). The cable system is connected at its ends to the threaded drum  118 , for example, at tie-offs  146 . Portions of the cable system are routed within the threads  116  of the drum  118 , thus enabling controlled winding and unwinding as the drum  118  rotates, without tangling of the cable system. During operation, as the drum  118  is rotated by either a motor or by hand, the cable system simultaneously winds onto and unwinds from the threaded drum  118 . The projection or spline  112  remains fixed within the threads  116  of the drum  118 . This causes the drum  118  to translate along the drive shaft  108  as the drum  118  rotates. This translation keeps the cable aligned with the openings  110  so as to smoothly pay out and take up cable during drum  118  rotation. The diameter and length of the drum  118  may be selected so as to pay out and take up the proper amount of cable so as to completely open and close an associated window sash. 
         [0019]    In order to properly route the cable system so as to reduce friction associated therewith, the drum drive systems depicted herein utilize pulleys and other roller supports disposed at various locations within and about a window frame. For example,  FIG. 3  depicts a schematic perspective view of corner bracket pulley system  300  utilized in a drum drive system for a window. The corner bracket pulley system  300  includes a body  302  that defines a plurality of channels  304  therein. Each channel  304  has disposed therein a roller  306  that is configured to rotate freely about a shared axle  308 . Each roller  306  accommodates a single length of cable or cord so as to smoothly change the direction of that cable or cord, while adding minimal friction to the system. For example, the corner bracket pulley system  300  may change the direction of the cable such that the cable enters the corner bracket pulley system  300  in a direction B and exits the corner bracket pulley system  300  in a direction C, about a 90° difference. The corner bracket pulley system  300  also defines one or more openings  310  so as to receive one or more fasteners that can secure the corner bracket pulley system  300  to a portion of the window frame. Typically, the corner bracket pulley system  300  is installed at corners of the window frame. 
         [0020]      FIG. 4  depicts a roller support  400  utilized in a drum drive system for a window. The roller support  400  includes a body  402  that defines a channel  404  therein. Roller supports with multiple parallel channels  404  may also be utilized. The channel  404  has disposed therein a roller  406  that is configured to rotate freely about an axle  408 . The roller  406  accommodates a single length of cable or cord so as to smoothly change the direction of that cable or cord, while adding minimal friction to the system. For example, the roller support  400  may change the direction of the cable such that the cable enters the roller support  400  in a direction B and exits the roller support  400  in a direction C, about a 90° difference. In another example, the roller support  400  may change the direction of the cable such that the cable enters the roller support  400  in a direction B and exits the roller support  400  in a direction D, about a 180° difference. Other, non-orthogonal changes in direction may be achieved with the roller support  400 , depending on the cable entry and exit locations. This versatility of the roller support  400  may enable the roller support  400  to be installed in a number of different locations about the window frame. 
         [0021]      FIG. 5  depicts a schematic view of a drive system  500  for a window. The window includes at least one sash  502  that may be operated by the drive system  500 . The sash  502  is linearly movable in a frame (depicted as fixed surfaces  504 ) to which a number of drive system  500  components are secured. For example, a drive mechanism  506 , such as that depicted in  FIGS. 1A-2  is installed above the header of the window frame  505 . Two corner bracket pulley systems  508  are depicted in upper corners of the window frame  504 , as are two roller supports  510  disposed proximate a lower portion of the frame  504 . Additionally, the single cable  512  is secured to anchors  514  on either side of the sash  502 . 
         [0022]    Here, the drive mechanism  506  includes a base  516  having end bearings  518 . In this case, a motor  520  rotates R a drive shaft  522  about which is translatably T disposed a threaded drum  524 . This drum  524  can be small in diameter and still pay out and take up the length of cable  512  needed to drive the window sash  502  through its full range of travel. The depicted drum  524  is drawn schematically only. As such, only a limited number of threads that do not contain cable are depicted. In a production model, the drum would be longer, with a greater number of open threads to receive cable while the drum rotates. The number and pitch of threads, drum diameter and length, number of cable wraps, and so on, may be selected as required or desired for a particular application. Two alignment rollers  526  are disposed proximate the base  516  so as to align the cable  512  with the threads  528  of the drum  524 . Cable tie-offs  530  are also depicted at ends of the drum  524 . A pay-out end of the cable  512  is secured at cable tie-off  530   a , and a take-up end of the cable  512  is secured at cable tie-off  530   b . The terms pay-out and take-up are relative terms used to explain the operation of the system  500 . A projection  532  is secured to the base  516  and penetrates the threads  528 . Arrows on the cable  512  depict one direction of travel upon rotation R of the drum  524 , so as to lift the sash  502 . An opposite rotation R of the shaft  522  reverses direction of the cable  512  so as to lower the sash  502 . 
         [0023]    During operation, as the motor  520  (or hand crank, in the case of a manual configuration) rotates R the drive shaft  522 , the drum  524  translates T back and forth along the shaft  522 , due to the fixed position of the projection  532 . As the drum  524  translates T, the take-up and pay-out points of the drum  524  remain aligned with the alignment rollers  526  that direct the path of the cable  512  moving to or from the drum  524 . The alignment rollers  526  are depicted fixed to the base  516 , generally proximate the projection  532 , but may be disposed elsewhere, as required or desired for a particular application of cable  512  routing configuration. The driven cable  512  loop runs across the head of the window and is routed by the corner bracket pulley systems  508  so as to run through both jambs. In certain examples, the corner bracket pulley systems  508  are integrated with a window balance that supports a non-powered sash. The cable  512  is routed around roller supports  510 . The cable  512  drives both sides of the sash  502 , thus ensuring that the sash  502  remains square in the frame  504 . 
         [0024]    The drum  524  can be either motor-driven, as depicted, or manual. The powered installation would be typically at the top of the unit near the middle of the top rail of the frame  504 . In other examples, the drive mechanism  506  can be installed at a bottom of the window, e.g., contained within the bottom rail. For a manual installation, the drum can be installed vertically, e.g., within, or surface mounted to, a side jamb of the window. A hand crank may penetrate the side jamb so as to be rotatable by a user. Other positions are contemplated. The thin configuration of the cable  512  allows it to be routed virtually anywhere within the window, regardless of drive mechanism  506  position. 
         [0025]      FIG. 6  depicts another schematic view of a drive system  600  for a window. The system  600  includes a number of components described above with regard to the system  500  depicted in  FIG. 5  that are numbered similarly. As such, certain of these components are not necessarily described further with regard to  FIG. 6 , but the operation thereof would be apparent to a person of skill in the art. As with the configuration of  FIG. 5 , the depicted drum  624  is drawn schematically only. As such, only a limited number of threads that do not contain cable are depicted. In a production model, the drum would be longer, with a greater number of open threads to receive cable while the drum rotates. The number and pitch of threads, drum diameter and length, number of cable wraps, and so on, may be selected as required or desired for a particular application. In this example, two cables  612   a ,  612   b  are utilized, with two take-up ends and two pay-out ends connected to the drum  624 . A pay-out end of the first cable  612   a  is secured at cable tie-off  630   a , and a take-up end of the first cable  612   a  is secured at cable tie-off  630   a ′. Similarly, a pay-out end of the second cable  612   b  is secured at cable tie-off  630   b , and a take-up end of the second cable  612   b  is secured at cable tie-off  630   b ′. The increased number of cables  612   a ,  612   b  necessitate the use of additional alignment rollers  626   a ,  626   a ′,  626   b ,  626   b ′. Again, the terms pay-out and take-up are relative terms used to explain the operation of the system  600 . Additionally, a hand-crank operator  620 ′ is utilized in the system  600 , although a motorized operator may also be utilized. 
         [0026]    While there have been described herein what are to be considered exemplary and preferred embodiments of the present technology, other modifications of the technology will become apparent to those skilled in the art from the teachings herein. The particular methods of manufacture and geometries disclosed herein are exemplary in nature and are not to be considered limiting. It is therefore desired to be secured in the appended claims all such modifications as fall within the spirit and scope of the technology. Accordingly, what is desired to be secured by Letters Patent is the technology as defined and differentiated in the following claims, and all equivalents.

Summary:
A threaded drum is rotated by a drive shaft. As the threaded drum rotates, part of a cable is wrapped around the drum, while at the same time, a second part of the cable is unwrapped from the drum. Rotation of the drive shaft is based on rotation of an operator.