Abstract:
A mounting assembly including a housing for a roller operated system, such as a projection screen system, which facilitates installation in a building in stages to reduce the risk of damage to system components. The housing includes longitudinally extending lipped projections along its top wall. Attachment lugs of brackets that support the roller on which a sheet, such as a projection screen, is windable are adapted to engage the lipped projections and enable the brackets to be mounted to the housing at selected longitudinal locations to allow for positioning adjustments of the roller. The vertical side walls of the housing also are each constructed with a projecting lip adapted to engage an upstanding hook of the bottom closure panel to thereby enable the closure panel to be mounted to either of the side walls of the housing. A method of installing a roller operated system is also disclosed.

Description:
This application is a divisional of U.S. application Ser. No. 08/859,027, filed May 20, 1997, now U.S. Pat. No. 6,137,629. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention pertains to roller operated systems, and, in particular, to mounting assemblies for rollers of such systems. 
     Projection screen systems in numerous forms are gaining frequent application in a variety of venues, including conference rooms in office buildings and home entertainment systems. Many such systems include an electrical motor that powers the raising and lowering of the screen relative to a housing that holds the screen mounting roller. The projection screen either winds on the roller or unwinds from the roller depending on the direction of rotation of the motor. Projection screen systems of this type frequently are completely installed into a building or structure at one time. During this installation process, an electrician is required to hardwire a power conduit within the structure to the projection screen system. The electrician then electrically connects the exposed wire leads of the power cord extending from the motor to this power conduit, and manipulates these electrical connections into a junction box mounted within the housing. One shortcoming of this one time system installation process is that the installed projection screen may be subjected to dust, dirt and other risks of damage that are inherent in being located in a construction zone for potentially long periods of time. However, installing the projection screen housing to the structure during a first stage of construction and then the projection screen during a subsequent stage of construction may be cost prohibitive. In particular, hiring an electrician to return to the building to wire the motor to the power conduit already installed by an electrician during building construction may increase installation costs appreciably. 
     Another shortcoming of many projection screen systems is the difficulty or inconvenience of properly positioning the projection screen within a room in which it is to be viewed. On occasion, whether it be due to an incorrect measurement during installation or a properly performed installation into a room that is subsequently altered before construction is finished, a person who lowers the screen for use may discover the screen to be off-center or improperly positioned within the room. For projection screen systems that support the screen mounting roller at the housing end caps, longitudinal adjustments of the screen may require the entire housing be moved to adjust the projection screen positioning. Other known systems of the type that employ roller mounting brackets that are attached with screws to the housing do allow the position of the roller to be adjusted without moving the system housing. However, this adjustment operation, as well as the process of initially installing the screen mounting roller, may be awkward and difficult for an installer to perform. In particular, this process requires the installer to hold the roller mounting brackets in place, typically above his or her head, while the brackets are initially attached, or detached and reattached in situations where a change in screen positioning is desired. 
     Another problem with some projection screen systems is that their construction frequently leaves little margin for error in the installation process. For example, if the housing is initially installed backwards with the wrong part of the housing facing into the room in which the projection screen is to be used, the housing must be removed, turned around and reinstalled. In addition, on occasion when the fully assembled system is operated and the screen is lowered, it may be discovered that the projection screen is too close to the wall to clear any artwork displayed on that wall. Even if that projection screen was installed to roll off the back of the roller within the housing, the roller typically is not capable of being quickly removed and reinstalled to allow the screen to roll off the front edge of the roller. This shortcoming is because the closure panel that partially blocks off the underside opening of the housing may not be readily installable to the back wall of the housing instead of the front wall where the panel was initially installed. Thus, it would be desirable to provide a system that overcomes these and other shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention provides a roller operated system, such as a projection screen system, that is installable in two stages such that portions of the system may be installed at different times during construction. A housing and roller mounting brackets are provided that are cooperatively shaped to enable the brackets to be temporarily installed to the housing without fasteners, as well as enable the brackets to be moved along the length of the housing to adjust the position of the roller. The housing is further designed in conjunction with the bottom closure panel to allow the panel to be attached to either the forward or rearward side wall of the housing, thereby affording the system the capability to be modified to meet the requirements of a given application. 
     In one form thereof, the present invention provides a mounting assembly for a projection screen windable on a roller including a housing and a plurality of roller holding brackets. The housing includes a plurality of walls and defines an interior volume for installation of the roller. The housing also includes at least one attachment lip overlaying a portion of one of the plurality of walls, wherein the attachment lip is in spaced apart relationship with the wall portion to define an insertion space. Each of the roller holding brackets includes at least one attachment lug complementarily structured for engagement with the at least one attachment lip. Each of the brackets is rotatable between first and second orientations, wherein each of the at least one attachment lug is structured and arranged to reside within the insertion space and engage the at least one attachment lip to mount its respective bracket to the housing when that bracket is arranged in the first orientation, and wherein each of the at least one attachment lug is structured and arranged to be clear of the insertion space and disengaged from the at least one attachment lip to permit removal of its respective bracket from the housing when that bracket is arranged in the second orientation. 
     In still another form thereof, the present invention provides a housing for a projection screen system including a projection screen windable on a roller. The housing includes a longitudinally extending first side wall, a longitudinally extending second side wall in spaced apart relationship with the first side wall, and a top member interconnecting the first and second side walls. The top member, the first side wall and the second side wall define an interior volume in which the roller is positionable. The housing also includes a longitudinally extending bottom closure panel sized to partially block a bottom facing opening between the first and second side walls and provide a gap for passage of the projection screen unwinding from the roller, wherein the closure panel includes an attachment module. Each of the bottom portions of the first and second side walls includes an attachment member complementarily structured for engagement with the closure panel attachment module, whereby the closure panel is removably mountable to either of the first and second side walls. 
     One advantage of the present invention is that it allows the housing of a projection screen system and the roller mounted projection screen to be installed at different stages of construction without requiring the installer of the screen to possess any electrical wiring expertise. 
     Another advantage of the present invention is that the roller mounted projection screen can be moved longitudinally to the left and to the right after installation has initially been made to properly locate the screen. 
     Still another advantage of the present invention is that the roller mounting brackets may be temporarily secured to the housing without additional fasteners to facilitate screen installation. 
     Still another advantage of the present invention is that the housing allows mounting of a bottom closure panel on either the front or back housing sides so as to provide suitable openings permitting the projection screen to roll off either the front or back of the roller. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above mentioned and other advantages and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a fragmentary front view of an assembled projection screen system of the present invention, wherein the system is partially shown in longitudinal cross-section and wherein the bottom closure panel is not shown; 
     FIG. 2 is a fragmentary bottom view of the projection screen system of FIG. 1, wherein the junction box cover, the electrical circuitry extending from the motor and within the junction box, and the weighted bottom portion of the projection screen have been removed for purposes of illustration; 
     FIG. 3 is a cross-sectional end view, taken along line  3 — 3  of FIG. 1, of the projection screen system of FIG. 1, wherein the bottom closure panel is shown installed; 
     FIG. 4 is a cross-sectional end view, taken along line  4 — 4  of FIG. 1, of the projection screen system of FIG. 1, wherein the bottom closure panel is shown installed, wherein the plug and socket connectors of the electrical circuitry are abstractly shown without their associated wiring, and wherein the roller and projection screen are not shown in cross-section; 
     FIG. 5 is a cross-sectional end view, taken along line  5 — 5  of FIG. 1, of the projection screen system of FIG. 1, wherein the bottom closure panel is shown installed, and wherein the plug and socket connectors of the electrical circuitry are abstractly shown without their associated wiring; 
     FIGS. 6A and 6B are side and top views of the motor end roller mounting bracket removed from the remainder of the projection screen system of FIG. 1; and 
     FIGS. 7 and 8 are similar cross-sectional end views diagrammatically showing a bottom closure panel mounted on different side walls of the housing and with the projection screen unwinding from different sides of the roller. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent an embodiment of the invention, the drawings are not necessarily to scale and certain features may be exaggerated or omitted in some of the drawings in order to better illustrate and explain the present invention. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 1-5, there are shown various views of an exemplary embodiment of a projection screen system, generally designated  10 , of the present invention in a screen storage arrangement. System  10  includes a protective housing  12  formed of a top wall or panel  14  having opposite side edge portions from which downwardly extend side wall  16  and side wall  18 . The shown orthogonal configuration of side walls  16  and  18  with respect to top wall  14  results in housing  12  having an inverted square U-shaped configuration, but other wall arrangements may be utilized in alternate embodiments. Housing  12  is fabricated from a lightweight and strong material such as aluminum. Housing  12  is preferably formed in one-piece in an extrusion process, but may be formed in alternate fashions, such as by rigidly interconnecting separate panels or plates. Along its longitudinal length that extends from end  20  to end  21 , housing  12  is uniformly configured, and therefore the shapes of the housing shown in FIGS. 3-5 are representative rather than merely coincidentally similar. In the shown embodiment, housing  12  is symmetrical about a vertical plane longitudinally extending through line  164  shown in FIG. 3, and therefore housing  12  may be installed such that either side wall  16  or side wall  18  is the front wall (i.e. the housing wall closer to the center of the room in which projection screen system  10  is to be viewed). 
     Housing side wall  16  includes a pair of screw channels  23 , and side wall  18  includes a pair of screw channels  24 . End cap  27  is attached to housing  12  by four screws  29  that insert into screw channels  23  and  24  and closes off the end of the interior volume defined by housing  12 . End cap  28  is similar attached with screws  30  to cap the opposite housing end. End caps  27  and  28  are formed of a high strength material, such as steel. End caps  27 ,  28  respectively include upper flanges  33 ,  34  that each include two apertures as shown in dotted lines in FIG.  2 . The apertured flanges  33 ,  34  may be attached to a support member of a structure in which projection screen system  10  is to be installed with any of a variety of conventional fasteners, such as threaded rods with locking nuts and wires as indicated in FIG. 1 at  36  and  37 , respectively. Housing  12  may alternatively be directly attached to the support member by fasteners that extend through a housing wall, such as top wall  14 . 
     Installed within the interior volume  38  formed by walls  14 ,  16  and  18  is a junction box, generally designated  40 , that furnishes a protected compartment for the electrical connections between projection screen system  10  and a conduit to the installation structure&#39;s power supply. Junction box  40  includes vertical side flanges  42  and  43  and a bottom facing horizontal flange  44  that substantially span the entire horizontal space between side walls  16  and  18 . Self-tapping screws  46  and  47  that fit through tabs  49 ,  50  horizontally extending from box flanges  42 ,  43  insert into a screw channel  52  formed into housing top wall  14  to mount junction box  40  to housing  12 . Junction box  40  may be manufactured by orthogonally bending a suitably sized and shaped single piece of sheet metal into the shown configuration. 
     Junction box  40  is positioned directly below an entry hole  55  in housing top wall  14  through which an electrical conduit (not shown) connected to a structure&#39;s power supply can be inserted. Bottom flange  44  includes a rectangular opening  57  which allows access to the interior or contents of box  40 . A junction box cover plate  59 , shown in dashed lines in FIG. 2, is attached to bottom flange  44  with not shown screws that insert through four holes  60  in flange  44 . A second opening  62  adapted to installably receive a power connector is also provided through bottom flange  44 . 
     Mounted to junction box  40  and positioned within the interior of box  40  is a power connector abstractly shown in FIG. 1 at  64 . Connector  64  includes a socket portion  65  from which extend four wire leads  67 . Socket portion  65  snap fits into flange opening  62  during installation so as to permit its connection with a complementary power connector in a convenient fashion and without removing cover plate  59 . Socket portion  65  includes hollows or sockets within its body that receive projecting plugs of a plug portion of a power connector. In the shown embodiment in which four wire leads  67  are employed, socket portion  65  includes four separate plug receiving sockets. Wire leads  67 , with the use of wire nuts (not shown), are attached to the end of the electrical conduit (not shown) hardwired into the building. A quick disconnect power connector external to junction box  40  is shown at  70  and includes a plug portion  72  from which project individual plugs insertable into the sockets of power connector  64 . Power connector  70  is circuited with a power cord  74  connected to screen motor  76 . Power connectors  64  and  70  may be readily mated together as described further below to operatively circuit motor  76  to the building&#39;s electrical power supply. One suitable type of power connector is available from AMP Incorporated of Harrisburg, Pa. as Universal Mate-N-Lok Connectors. Other styles of plug/socket connectors, as well as other types of connectors readily connectable without handling of potentially hot wiring, may be substituted for the shown connectors  64  and  70  within the scope of the invention. 
     As shown in FIG. 3, downwardly projecting from top wall  14  are two L-shaped projections or interactive members, generally designated  80  and  84 , that extend the longitudinal length of housing  12  and allow for the adjustable attachment of a projection screen assembly to housing  12 . Projection  80  includes a vertically projecting flange  81  that terminates with a horizontally extending lip portion  82  pointing toward the middle of top wall  14 . The upper surface of lip portion  82  is spaced from the region of top wall  14  which it overlays to provide an insertion space for bracket mounting as described below. Projection  84  is a mirror image of projection  80  and includes flange  85  and lip portion  86 , which points toward lip portion  82 . Projections  80  and  84  are integrally formed with top wall  14 , but in alternate embodiments may be provided on side walls  16  and  18 , such as if a roller is to be mounted to that side wall. Differently shaped projections, such as slat-shaped flanges that are inclined relative to top wall  14 , may be substituted for the L-shaped projections shown. In addition, the insertion spaces defined by projections  80  and  84  may be provided by recesses provided in the housing walls within the scope of the invention. 
     A projection screen assembly that may be readily mounted to housing  12  subsequent to the installation of housing  12  in a building is generally designated  100  and includes brackets  102  and  104  directly attachable to housing  12 . FIGS. 6A and 6B are further described as showing views of bracket  102 , but this shown bracket configuration enables its use as either bracket  102  or  104 , which simplifies manufacture and assembly. Bracket  102  includes an attachment flange  106  from which downwardly extends support flange  108 . Four tapped holes  107  through flange  106  receive set screws  116  (See FIG.  1 ). The end regions  110  and  112  of flange  106  serve as attachment lugs or interactive members. Attachment lugs  110 ,  112  have a thickness insertable into the space between top wall  14  and the lip portions  82  and  86  of lipped projections  80  and  84 . Attachment lugs  110  and  112  further are sized such that the distance from the outward edge of attachment lug  110  to the outward edge of attachment lug  112 , as measured in a direction perpendicular to a roller when installed to bracket  102 , is greater than the distance between the tips of lip portions  82  and  86  but less than the distance between flanges  81  and  85 . Diagonally opposite or catercorner portions  113  and  114  of attachment lugs  110  and  112  are rounded such that the diagonal length therebetween is less than the distance between flanges  81  and  85  to allow a rotational bracket installation described further below. Support flange  108  includes horizontally spaced apertures  115 , vertically spaced apertures  119 , and a central aperture  121 . Apertures  119  and  121  are not used in bracket  102 , but when a bracket shaped as shown in FIGS. 6A and 6B is used as bracket  104 , such apertures respectively receive dampener mounting screws and an idler shaft as described further below. Bracket  104  is configured identical to bracket  102  and generally includes an attachment flange  117  and support flange  118  (See FIG.  1 ). 
     Although configured as an outwardly extending and coplanar continuation of bracket flange  106  in the illustrated embodiment, attachment lugs  110  and  112  may be differently configured within the scope of the present invention. In alternate embodiments, for example, lugs  110  and  112  may be provided as tabs projecting from support flange  108 , or as movable members shiftable along attachment flange  106 . 
     Operationally supported by bracket  102  is the electric motor  76  connected to power cord  74 . The rotatable output shaft of motor  76  is operationally attached to a cylindrical roller  120  in a well known fashion. Motor  76  includes a square stud (not shown) that projects from the motor housing and inserts into a square throughbore provided in a finned insert (not shown) made of aluminum molded into dampener  128 . The finned insert engages the motor housing stud to prevent relative rotation therebetween. Sound dampener  128  is formed of thermoplastic rubber and includes two laterally extending projections  130  into which are integrally molded T-nuts  132 . A pair of screws  134  extend through apertures  115  in support flange  108  and engage the internal threads of T-nuts  132  to mount dampener  128  to bracket flange  108 . 
     Shown wound around roller  120  and unwindable therefrom upon roller revolution is a sheet of fabric  122  that serves as a projection screen. Projection screen  122  is shown in FIGS. 1-5 in a retracted position fully stored within the protective housing  12 . As is conventional when used as a front projection screen, one surface of fabric sheet  122  is of the type of material on which images may be projected for viewing, and the opposite surface is formed of an opaque material. The lower end of fabric sheet  122  is looped and secured around a dowel abstractly indicated at  126 . Dowel  126  serves as a suspended weight that causes screen  122  to descend in a relatively planar configuration as it unwinds from roller  120 . 
     At the end of roller  120  opposite the end to which motor  76  is attached, an idler shaft  137  is fixed to roller  120  to be rotatable therewith. Idler shaft  137  extends through a flanged nylon bushing  139  mounted within thermoplastic rubber dampener  141 , and through a central aperture (corresponding to aperture  121  through support flange  108 ) in support flange  118 . Slipped over the end of idler shaft  137  is a washer  143 , and spring clip  145  attaches around shaft  137  to prevent shaft  137  from being axially withdrawn through flange  118 . Two screws  147 ,  149  insert through vertically spaced holes through flange  118  to threadedly engage T-nuts (not shown) integrally molded into dampener  141  to mount dampener  141  to flange  118 . 
     With particular reference to FIG. 3, a lipped projection  154  projects inwardly from an interior surface  153  of an outwardly offset lower region  152  of housing side wall  16 . A second lipped projection  156  projects from surface  153  below projection  154 . Lipped projections  154  and  156  extend the longitudinal length of side wall  16 . The outwardly offset lower region  158  of housing side wall  18  similar includes lipped projections  160  and  162 , which are mirror images of projections  154  and  156 . 
     A bottom closure panel  166  made of aluminum that extends the entire longitudinal length of housing  12  and which has a uniform cross-section along its length includes an attachment member  168  comprising hook end  170 . Closure panel  166  is sized narrower than the space or opening between side walls  16  and  18  such that when attached to either side wall  16  or side wall  18 , closure panel  166  defines a slot shaped gap  172  with the side wall to which it is not attached. The projection screen  122  can be lowered and raised through this gap  172  during system operation. 
     Hook end  170  fits over the upturned lip of lipped projection  154  as shown in FIG. 3 to mount closure panel  166  to side wall  16 . The lip of lipped projection  156  provides an enlarged bearing surface against which the side surface of attachment member  168  abuts when installed. An upstanding longitudinal rib  174  stiffens panel  166  to resist panel bowing. Nub  176  that laterally extends from rib  174  and a longitudinally extending L-shaped rib  178  define a channel  180 . Not shown brackets insertable into channel  180  at opposite ends of panel  166  include upstanding leaf spring portions with longitudinally projecting pins. Apertures (not shown) on end caps  27  and  28  receive the pins of the leaf spring portions when closure panel  166  is installed to line up the panel housing and prevent panel sag. 
     Attachment member  168  may be used to attach to either lipped projection  154  or  160  due to the projections complementary structure with member  168 . Other detachable, interconnecting structures, including housing recesses or apertures that releasably receive prongs of the closure panel, may be employed within the scope of the invention. 
     Referring now to FIGS. 7 and 8, the installation adaptability afforded by the configuration of the housing and closure panel of projection screen system  10  is further illustrated. FIG. 7 diagrammatically shows projection screen  122  unwinding from roller  120  installed within housing  12  and passing through gap  172 . As closure panel  166  is mounted to side wall  16 , gap  172  is provided between the edge of panel  166  and side wall  18 . Depending on the requirements of a user of system  10 , the viewing surface of screen  122  may be furnished on either surface  183  or surface  184 . In screens fabricated with only one surface being a viewing surface, the direction that surface faces is controlled by the manner in which screen  122  is wrapped around roller  120 . In the diagrammatic view of FIG. 8, closure panel  166  is mounted to side wall  18  and consequently projection screen  122  unwinding from roller  120  passes through gap  172  formed between the edge of panel  166  and side wall  16 . The viewing direction of screen  122  in FIG. 8 may be from either side. 
     The structure of projection screen system  10  will be further understood in view of the following explanation of its installation and operation. A first stage of installation typically involves mounting an assembly including housing  12  to the structure, such as to a beam above the room in which system  10  is intended to be used. After end caps  27  and  28  and junction box  40  are preinstalled or fastened to the housing ends and top wall  14 , respectively, end caps  27 ,  28  may be used to mount this screen assembly to the structure. At this stage of installation, the remainder of projection screen system  10  is not installed within housing  12 . For example, roller  120  with projection screen  122 , as well as roller mounting brackets  102  and  104 , have yet to be installed, and for that matter may be safely held in storage at another location where it is clear of the risk of damage from the construction site environment. After housing  12  is secured to the structure, an electrical conduit is routed through entry hole  55  and into junction box  40 . After an electrician removes cover plate  59  and electrically interconnects lead wires  67  to the appropriate wires of the electrical conduit, socket portion  65  is snap fit into opening  62  of junction box  40  and cover plate  59  is fastened to flange  44 . 
     Projection screen assembly  100  is subsequently installed to the previously installed housing assembly. This installation step, which may occur immediately after housing  12  installation but normally is delayed until construction of the building is essentially complete, begins with roller mounting brackets  102  and  104  separated from roller  120 . Roller bracket  102  is manipulated by an installer such that attachment flange  106  rests substantially flush with the interior surface of housing top wall  14  between lipped projections  80  and  84 . Due to the span of attachment lugs  110  and  112  being larger than the gap between lip portions  82  and  86 , to so manipulate bracket  102  an installer must arrange bracket  102  in a rotational orientation different from the installed arrangement shown in FIG. 1, such as about a forty-five degree rotation counter-clockwise from the perspective of a FIG. 2 viewer therefrom. As bracket  102  is then rotated (in a clockwise direction from the perspective of a FIG. 2 viewer) while being held at the same elevation, attachment lugs  110 ,  112  are rotated into the insertion spaces between top wall  14  and lip portions  82  and  86 . The truncated corner portions  113  and  114  do not engage the flanges of the lipped projections and thereby do not prevent this rotational insertion of the attachment lugs  110  and  112 . The underside of attachment lugs  110  and  112  abut the upper surfaces of lips  82  and  86  to prevent bracket  102  from falling out from housing  12 . 
     After bracket  104  is mounted to housing  12  in a similar fashion, namely by first positioning it in a rotational offset arrangement and rotating it such that the attachment lugs of its attachment flange insert and engage the attachment lips  82  and  86 , the roller  120  and its associated mounting accessories may be installed between the mounted brackets. The longitudinal position of roller  120  may be adjusted along the length of housing  12  by sliding brackets  102  and  104  within the channel defined between projections  80  and  84 . When the proper longitudinal positioning of screen  122  has been achieved, the set screws through the attachment flanges of each of the roller mounting brackets may be tightened to lock brackets  102  and  104 , and thereby lock screen  122  in its longitudinal position. 
     Next, an operator may take the power connector  70  attached to power cord  74  and simply plug it into the exposed socket portion  65  of power connector  64 . It will be appreciated that no electrician is required for this plug insertion, but rather a person with minimal mechanical aptitude may complete the circuiting of electrical motor  76  with the power supply. 
     The next installation step is to mount bottom closure panel  166 . An installer may simply maneuver closure panel  166  such that hook end  170  fits over lip projection  154 . This positioning may be performed by tilting upward the end of the panel opposite attachment member  168  and then lowering it after the hooking process is complete. After the closure panel has been manipulated such that the brackets mounted in channell  80  engage the apertures of end caps  27  and  28 , installation is complete. Subsequent operation of motor  76  allows roller  120  to revolve, which in turn causes projection screen  122  to unwind therefrom and pass down through gap  172  to a lowered position where an image can be projected on its surface for viewing. Motor  76  is reversible to wind screen  122  around roller  120  to raise screen  122 . 
     It will be recognized that if an installer wishes to have the screen unwind from the opposite side of roller  120 , the screen assembly may be flipped and the closure panel  166  mounted to lipped projection  160 . Housing  12  need not be removed from its installed position to achieve this modification. 
     While this invention has been shown and described as having multiple designs, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.