Patent Publication Number: US-7901213-B1

Title: Erasable marker screen assembly

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/796,825, filed May 2, 2006, the entire contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present invention relates to erasable marker boards. 
     Erasable marker boards or whiteboards are often used in classrooms, offices, conference rooms, etc. Typically, the marker boards include a smooth, white surface that can be written on using a dry erase marker. The marker boards can be erased using a dry eraser. 
     SUMMARY 
     Typical marker boards are generally rigid and are fixed to a wall such that the marker board is immobile. It is desirable for a marker board to be mobile so that the user can take the marker board to a different office, classroom, conference room, etc. Furthermore, it can be desirable to selectively hide or cover the information written on the marker board. Typically marker boards have been supplied within cabinets or doors in order to cover the marker board when the user desires. However, these solutions limit the mobility of the marker board. Therefore, it is desirable to create a marker board assembly that is both mobile and able to cover or hide the information written on the marker board. 
     In one embodiment, the invention provides an erasable marker screen assembly that includes a marker screen, a housing, and a rolling mechanism configured to roll the marker screen within the housing. 
     In another embodiment, the invention provides a marker screen assembly that includes a housing, a first screen stored within the housing and movable to an extended position, and a second marker screen stored with the housing and movable to an extended position. The second marker screen has a writing surface designed to be repeatably written upon and erased and is configured to overlay at least a portion of the first screen when both the first and second screens are in the extended position. 
     In yet another embodiment, the invention provides a marker screen assembly that includes a first housing, a first screen stored within the first housing and movable to an extended position, and a second housing adjacent to the first screen. The marker screen assembly also includes a second marker screen stored within the second housing and movable to an extended position. The second marker screen has a writing surface designed to be repeatably written upon and erased and is configured to overlay at least a portion of the first screen when both the first and second screens are in the extended position. 
     In still another embodiment, the invention provides a portable marker screen assembly that includes a housing sized and configured to be carried by a user, and a coupling member connected to the housing and configured to removably couple the housing to a surface. The portable marker screen assembly also includes a marker screen stored within the housing and movable to an extended position. The marker screen has a writing surface designed to be repeatably written upon and erased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an erasable marker screen assembly embodying the present invention. 
         FIG. 1   a  is an enlarged view of a portion of the marker screen assembly of  FIG. 1 . 
         FIG. 2  is another front perspective view of the marker screen assembly of  FIG. 1 . 
         FIG. 2   a  is an enlarged portion of  FIG. 2  showing an integral marker holder. 
         FIG. 3  is yet another front perspective view of the marker screen assembly of  FIG. 1 . 
         FIG. 3   a  is an enlarged portion of  FIG. 3  showing a coupling member of the marker screen assembly. 
         FIG. 4  is a rear perspective view of the marker screen assembly of  FIG. 1 . 
         FIG. 4   a  is an enlarged portion of  FIG. 4  showing the coupling member of the marker screen assembly. 
         FIG. 4   b  is an enlarged portion of  FIG. 4  showing the interface between the marker screen and the housing of the marker screen assembly. 
         FIG. 5  is a side view of the marker screen assembly of  FIG. 1 . 
         FIG. 6  is a front view of the marker screen assembly of  FIG. 1 . 
         FIG. 7  is another side view of the marker screen assembly of  FIG. 1 . 
         FIG. 8  is a bottom view of the marker screen assembly of  FIG. 1 . 
         FIG. 9  is yet another front perspective view of the marker screen assembly of  FIG. 1  showing the marker screen extended from the housing. 
         FIG. 10  is a front perspective view of the marker screen assembly of  FIG. 1  showing the marker screen retracted within the housing. 
         FIG. 11  is a perspective view showing one application of the erasable marker screen assembly of  FIG. 1  with the marker screen retracted within the housing. 
         FIG. 12  is a perspective view of the marker screen assembly of  FIG. 11  showing the screen extended a first length from the housing. 
         FIG. 13  is a perspective view of the marker screen assembly of  FIG. 11  showing the screen extended a second length from the housing. 
         FIG. 14  is front perspective view of an alternative construction of a marker screen assembly showing the marker screen extended from the housing. 
         FIGS. 15   a - 15   d  show various embodiments of the marker screen assembly of  FIG. 14  with the marker screen retracted within the housing. 
         FIGS. 16-17  illustrate one application of the marker screen assembly of  FIGS. 1 and 14 . 
         FIGS. 18-21  illustrate yet another alternative construction of a marker screen assembly. 
         FIGS. 22-26  illustrate yet another alternative construction of a marker screen assembly. 
         FIGS. 27-29  illustrate yet another alternative construction of a marker screen assembly. 
         FIG. 30  is an exploded view of yet another alternative construction of a marker screen assembly. 
         FIG. 31   a  is a side view of the marker screen assembly of  FIG. 30  showing marker screens extended from housings. 
         FIG. 31   b  is a side view of the marker screen assembly of  FIG. 30  showing the marker screens retracted within the housings. 
         FIG. 31   c  is a side view of the marker screen assembly of  FIG. 31   b , where the marker screen assembly includes a shroud. 
     
    
    
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and coupled “coupled” are not restricted to physical or mechanical connections or couplings. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an erasable marker screen assembly  20  that includes a housing  22  and a retractable screen  24  that is stored within the housing  20 . The illustrated housing  22  is a generally tubular member with end caps  26 . In other constructions, the housing  22  can have a plurality of generally flat sides (i.e., rectangular, pentagonal, hexagonal, etc.) or may take other suitable shapes. 
     The illustrated housing  22  includes a recess  28  that stores or retains a marker  30  or other suitable writing instrument. In other constructions the housing  22  can include additional recesses or holders for writing instruments, erasers, pointers, other office supplies and the like. The housing  22  can also include a strap, handle  31  (shown only in  FIG. 1 ), or other suitable carrying member that facilitates transporting the marker screen assembly  20 . 
     Referring to  FIGS. 2 and 4 , the illustrated housing  22  further includes coupling members  32 . The coupling members  32  can be any suitable member that couples the erasable marker screen assembly  20  to a surface such as a wall (i.e., drywall, cubical wall, glass wall, etc.), window, ceiling, chalkboard, existing dry erase board, or any other suitable surface. The coupling members  32  can include suction cups, magnets, brackets, hooks, adhesives, VELCRO, apertures, and the like. In other constructions, the coupling members  32  can be configured to couple the marker screen assembly  20  to a folding stand, easel, and the like. 
     Some of the coupling members  32  described above (e.g., suction cups, magnets) generally facilitate removably coupling the marker screen assembly  20  to a surface, stand, etc., such that the marker screen assembly  20  is easily portable or mobile, and do not require any permanent alteration or addition to the mounting surface (e.g., receiving brackets, nail/screw holes, etc.). In other constructions, the coupling members can be configured to more permanently mount the marker screen assembly  20  to a wall, window, within or to a ceiling, and the like. 
     Referring to  FIGS. 3 and 4 , the erasable marker screen  24  includes a writing surface  34  and a writing surface support member or backing  38 . In the illustrated construction the writing surface  34  is a generally smooth and glossy surface that can be written on using the marker  30  and then erased. In other constructions, the writing surface can be a lenticular surface that can be written on and then erased. The writing surface  34  can be applied to the support member/backing  38  in any suitable manner (e.g., laminating, spray coating, other coating processes, etc.), or can be integrally formed with the support member/backing  38 . 
     The marker  30  can be any suitable marker such as a dry erase marker, permanent marker, wet erase marker, and the like. In one construction, the marker  30  is a marker or pen that has a leuco dye or similar system, but no dry erase oils. When such a marker is used on the writing surface  34 , it works and looks like a standard dry erase marker or pen. However, the marker can only be erased with a wet eraser. A standard dry eraser, dry cloth, or the user&#39;s finger will not erase the writing. Such a marker is advantageous for use with the illustrated marker screen  24  that retracts into the housing  22  because the writing from a typical dry erase marker may smudge or smear when the marker screen  24  is rolled within the housing  22  (discussed below). 
     It should be understood that a typical dry erase marker can be used with the erasable marker screen assembly  20  and the writing surface  24 . Other constructions of the marker screen assembly  20  may include features that prevent smearing and smudging of writing created with a typical dry erase marker or pen when the marker screen is retracted within the housing  22 . 
     The wet erase marker described above is just one possible construction of a wet erase marker and other types of wet erase markers or pens can be utilized with the writing surface  24  of the erasable marker screen assembly  20 . For example, the marker or pen may include a die that is only erasable with an amine-water eraser or similar, and not a dry eraser. Such an eraser may utilize a solvent that decolorizes the marker die so that the die disappears rather than smudges. In other constructions, the marker may combine a solvent that decolorizes the marker die and alternative dry erase oils that partially polymerize the marker die on contact with air. Such a marker would provide the experience and functionality of a dry erase marker, but the ink gains permanence upon standing and the marker would not be erasable with a typical dry eraser, dry cloth, the user&#39;s finger, etc. 
     Referring to  FIGS. 3 and 4 , the illustrated writing surface  34  is formed on a flexible sheet  42  that can be rolled within the housing  22 . The sheet  42  is coupled to the writing surface support member  38 . The writing surface support member  38  can be any suitable member that provides rigidity to the sheet  42  and the writing surface  34  while still being able to roll within the housing  22 . In one construction, the support member  38  can be an inflatable air bladder. In such constructions, the erasable marker screen assembly  20  may include a fan, blower, etc. that inflates the bladder after at least a portion of the sheet  42  has been removed from the housing  22 . The user can then deflate the bladder when the user desires to roll the sheet  42  and the surface support member  38  within the housing  34 . 
     In other constructions, the writing surface support member  38  can be formed from a plastic or thin metal material and constructed to be selectively rollable or ridged. In such constructions, the user can deflect the marker screen  24  causing the surface support member  38  to be either slightly concave or slightly convex. As viewed from the writing surface  34 , when the surface support member is slightly concave it can be rolled, and when the surface support member is slightly convex it is rigid. 
     In yet other constructions, the writing surface support member  38  can be a generally thin sheet that is not substantially rigid or can be integral with the flexible sheet  42 . In such constructions, the marker screen assembly  20  can utilize a wall, chalkboard, or any underlying surface to provide support for the writing surface  34 . 
     Referring to  FIG. 1 , the erasable marker screen  24  further includes a first end portion  46  and a second end portion (not visible) that is retained within the housing  22 . In the illustrated construction, a handle  50  is coupled to the first end portion  46  of the marker screen  24 . The illustrated handle  50  extends along the entire width of the first end portion  46  to provide support and rigidity to the first end portion  46  of the marker screen  24 , although this need not be the case in alternative embodiments. While not illustrated, the handle  50  could include an aperture to facilitate grasping and/or to help secure the screen  24  in the extended position. 
     Referring to  FIGS. 1 and 1   a , one or more coupling members  54  are coupled to the handle  50  of the marker screen  24 . The coupling members  54  can be any suitable member that couples the marker screen  24  to a surface such as a wall, window, ceiling, chalkboard, existing dry erase board, or any other suitable surface. Similar to the coupling members  32  of the housing  22  ( FIG. 2 ), the coupling members  54  of the marker screen  24  can include suction cups, magnets, brackets, hooks, adhesives, VELCRO, apertures, and the like. In other constructions, the coupling members  54  can be configured to couple the marker screen assembly  20  to a folding stand, easel, and the like. 
     While not illustrated, the marker screen assembly  20  includes a rolling mechanism within the housing  22  that is operable to roll the marker screen  24  around a shaft that is also within the housing  22 . These types of rolling mechanisms are known in the art and typically include a rotational spring that biases and rotates the shaft. A clutch can be incorporated to hold the marker screen  24  in extended positions or allow the user to selectively retract the marker screen  24  within the housing  22 . Somewhat similar mechanisms can be found in window shades, projector screens, and the like. 
     Referring to  FIG. 1 , while the illustrated marker screen assembly  20  includes a single writing surface  34 , in other constructions the marker screen assembly  20  can include multiple writing surfaces. For example, in one construction, such as the marker screen assembly of  FIGS. 18-21  (discussed below), the marker screen assembly  20  includes a second marker screen that is extendable from the housing to cover all or a portion of the illustrated writing surface  34 . The second marker screen can include attachment members  536  ( FIG. 31   a ), such as clips, clamp, hooks, magnets apertures, and the like to couple the second screen in an extended position to the first marker screen  24  (e.g., to the handle  50  or a portion of the perimeter of the first screen  24 ). 
     In one construction, the second screen is translucent or transparent such that the writing or images on the first screen  24  are visible through the second screen, as shown in  FIGS. 27-29 . The user can write on the second screen, similar to the first screen  24 , to overlay writing or images on the second screen with writing or images on the first screen  24 . In yet other constructions, the marker screen assembly  20  can include any suitable number of screens similar to the first screen  24  or the second screen described above. In addition, the additional marker screens can have different lengths and/or widths than the first marker screen  24  and each other. 
     The marker screen assembly  20  can include additional rolling mechanisms so that each of the additional screens can be independently extended from or retracted within the housing  22 . The configuration of the housing  22  can vary accordingly. 
     It should be understood that the marker screen assembly  20  of  FIGS. 1-13  is just one possible size of the marker screen assembly  20 . In other embodiments, the marker screen assembly  20  can be made in any suitable size. For example, smaller versions of the marker screen assembly  20  can be sized to fit within purse, backpacks, binders, etc. Larger versions of the marker screen assembly  20  can be made for larger classrooms, conference rooms, offices, etc. 
     Referring to  FIGS. 11 and 12 , in operation, the user couples the marker screen assembly  20  to a surface  58  using the coupling members  32  of the housing  22 . The user grabs the handle  50  of the marker screen  24 , which is biased into the retracted position ( FIG. 11 ), and pulls the screen  24  to extend at least a portion of the screen  24  from the housing  22 . As illustrated in  FIGS. 12 and 13 , the user can extend the screen  24  to any suitable length. The clutch of the rolling mechanism can hold the marker screen  24  in the extended position at any length desired by the user. If the support member  38  can be inflated or otherwise manipulated to add rigidity to the writing surface  34 , the user can next take such action. 
     Then, the user utilizes the coupling members  54  of the marker screen  24  ( FIG. 3 ) and handle  50  to couple the marker screen  24  to the surface  58 . 
     While the illustrated screen  24  of the marker screen assembly  20  opens or extends from the user&#39;s left to right, in other embodiments the screen can extend in any direction with respect to the user. For example, the marker screen assembly  20  can be mounted such that the screen extends upwards, downwards, left to right, right to left, diagonally, etc. 
     With the screen  24  at least partially extended from the housing  22 , the user can write on the writing surface  34 , generally indicated by a line  62 , using the marker  30 . When the user has finished writing they can erase the writing or retract the screen back within the housing  22  ( FIG. 11 ) prior to erasing the writing. 
     The user may desire to retract the screen  24  within the housing  22  without erasing the writing. For example, in some situations the user may not want to reveal or disclose information on the writing surface  34 . Therefore, when desired, the user can retract the screen  24  within housing  22 . Similarly, the user may want to leave the writing or information on the screen  24  so that the writing can be displayed again at a later time, possibly in a different location. As discussed above, the marker  30  that is only erasable using a wet eraser reduces smudging or smearing of the writing when the screen  24  is retracted within the housing  22 . 
     As illustrated in  FIG. 11 , the user can retract the marker screen  24  to within the housing  22 . Then, the user can decouple the marker screen assembly  20  from the surface  58  to allow the user to easily move the writing assembly  20  to a different location (i.e., another room, building, etc.). In some embodiments a locking mechanism can be included to lock the screen  24  inside the housing  22 . Any suitable locking configurations (e.g., key locks, combination locks, push button locks, etc.) can be used. 
       FIGS. 16 and 17  illustrate possible applications of the erasable marker screen assembly  20 . In the illustrated applications, the marker screen assemblies  20  are coupled to glass walls  64 . Glass walls, similar to the glass walls  64  of  FIGS. 16 and 17 , have become more common in office buildings. Generally, it can be difficult or unsightly to mount standard dry erase marker boards to a glass wall. However, the marker screen assembly  20  provides a convenient solution for attaching a marker screen or board to a glass wall. Furthermore, the marker screen assemblies  20  can be easily removed from the glass walls  64 . 
     While operation of the marker screen assembly  20  was described with reference to a single marker screen assembly, it should be understood that multiple marker screen assemblies can be utilized. For example, the user can arrange two marker screen assemblies  20  such that both screens extend to couple the handles  50  together to hold the marker screens in the extended or open position. Of course, other configuration of multiple marker screen assemblies can also be utilized. 
       FIG. 14  illustrates an alternative construction of the erasable marker screen assembly  20  of  FIGS. 1-13 . The erasable marker screen assembly  120  of  FIGS. 14-15   d  is generally the same as the writing assembly  20 . Therefore, like components have been given like reference numbers plus one hundred, and only the general differences between the erasable marker screen assemblies  20  and  120  will be discussed below. 
     With continued reference to  FIG. 14 , the erasable marker screen assembly  120  includes the housing  122 . The housing  122  includes a door  168  that grants access to an integral storage compartment  170 . The storage compartment  170  can be used to store a stand for the marker screen assembly  120 , erasers  174 , markers  130 , pens, other office supplies, and the like. 
     In operation, the user can open the door  168  of the housing  122  and use an inner surface of the door  168  as a tray to conveniently support markers  130 , erasers  174 , pens, other office supplies and the like. 
     Referring to  FIG. 15   a , the user can close the door  168  to enclose the storage compartment  170 . While  FIG. 15   a  illustrates the door  168  in the closed position when the marker screen  124  is in the retracted positions, the door  168  can also be closed when the marker screen  124  is in the extended position.  FIGS. 15   a - 15   d  illustrate various embodiments of an outer surface of the door  168  and the housing  122 . 
       FIGS. 18-21  illustrate yet another alternative construction of the erasable marker screen assembly  20  of  FIGS. 1-13 . The erasable marker screen assembly  220  of  FIGS. 18-21  is generally the same as the writing assembly  20 . Therefore, like components have been given like reference numbers plus two hundred, and only the general differences between the erasable marker screen assembly  220  and the erasable marker screen assemblies  20  and  120  will be discussed below. 
       FIG. 18  illustrates the marker screen assembly  220  that includes the first screen  224  and a second screen  276  that can overlay or cover the first screen  224 . The illustrated second screen  276  includes a handle  278  that is generally the same as the handle  250  of the first screen  224 . 
     Referring to  FIG. 19 , writing, graphs, images, and the like can be placed on the writing surface  234  of the first screen  224 . Referring to  FIG. 20 , the user can pull the second screen  276  across a portion of the first screen  224  to overlay or cover the first screen  224 . As illustrated in  FIG. 20 , the second screen  276  can be extended to only partially cover the first screen  224 , or, as illustrated in  FIG. 21 , the second screen  276  is extendable to fully cover the first screen  224 . Furthermore, the second screen  276  includes a writing surface  280  that is generally identical to the writing surface  234  of the first screen  224 . In other constructions, the writing surface  280  of the second screen  276  can be generally translucent or transparent such that images on first screen  224  are visible through the second screen  276 . In such constructions, the user can write on the writing surface  280  of the second screen  276  to highlight or overlay images on the first screen  224 . 
       FIGS. 22-26  illustrate yet another alternative construction of the erasable marker screen assembly  20  of  FIGS. 1-13 . The erasable marker screen assembly  320  of  FIGS. 22-26  is generally the same as the writing assembly  20 . Therefore, like components have been given like reference numbers plus three hundred, and only the general differences between the erasable marker screen assembly  320  and the erasable marker screen assemblies  20 ,  120 , and  220  will be discussed below. 
     Referring to  FIGS. 22 and 23 , the erasable marker screen assembly  320  includes the housing  322 , which is a first housing, and a second housing  382 . In one construction, the rolling mechanism that rolls the first screen  324  is within the first housing  322 . The second housing  382  is coupled to the first end portion  346  of the first screen  324 , and a rolling mechanism that rolls the second screen  376  is located within the second housing  382 . In alternative constructions, rolling mechanisms are located in both the first and second housings  322 ,  382  to roll the first screen  324 . Therefore, approximately half of the first screen  324  retracts into the first housing  322  while the other half retracts into the second housing  382 . 
     Referring to  FIG. 23 , in operation, the user separates or pulls apart the first and second housings  322 ,  382  to extend or open the first screen  324 . Referring to  FIGS. 24-26 , the user can then operate the second screen  376  as described above with regard to  FIGS. 1-13  and  18 - 21 . 
       FIGS. 27-29  illustrate yet another alternative construction of the erasable marker screen assembly  20  of  FIGS. 1-13 . The erasable marker screen assembly  420  of  FIGS. 27-29  is generally the same as the writing assembly  320 . Therefore, like components have been given like reference numbers plus 100, and only the general differences between the erasable marker screen assembly  420  and the erasable marker screen assemblies  20 ,  120 ,  220 , and  320  will be discussed below. 
     Referring to  FIGS. 27-29 , the erasable marker screen assembly  420  includes the first housing  422 , the first screen  424  partially received within the first housing  422 , and the second housing  482  coupled to the first end  446  of the first screen  424 . In the illustrated construction, the second screen  478  is a translucent or transparent screen. The translucent second screen  478  allows writing or images on the first screen  424  to remain visible through the second screen  478 , while also allowing a user to add additional writing or images on the second screen  478  without disturbing or altering the writing or images on the first screen  424 . 
       FIGS. 30-31   b  illustrate yet another alternative construction of the erasable marker screen assembly  20  of  FIGS. 1-13 . The erasable marker screen assembly  520  of  FIGS. 30-31   b  is generally the same as the writing assembly  20 . Therefore, like components have been given like reference numbers plus 500, and only the general differences between the erasable marker screen assembly  520  and the erasable marker screen assemblies  20 ,  120 ,  220 ,  320 , and  420  will be discussed below. 
     Referring to  FIG. 30 , the erasable marker screen assembly  520  includes the first screen  524  coupled to a first rolling mechanism  584  of the first housing  522  and the second screen  578  coupled to a second rolling mechanism  586  of the second housing  582 . In the illustrated construction, the second screen  578  is opaque, but in other constructions the second screen  578  may be translucent or transparent. The second housing  582  couples to the first screen  524  adjacent to the first housing  522  with brackets  588  ( FIGS. 31   a  and  31   b ), although other suitable coupling elements may be used. In some constructions, such as the construction shown in  FIG. 31   c , a shroud  589  or other suitable structure may at least partially surround, interconnect, or unitize the first and second housings  522 ,  582  to provide an ornamental or aesthetic cover (i.e., a single housing) and/or to render the marker screen assembly  520  a modular or unitized assembly. 
     As shown in  FIG. 30 , the first screen  524  includes the handle  550  and a border  590 . The handle  550  is coupled to an opposite end of the first screen  524  than the first housing  522  and is configured to hold markers, erasers, office supplies, or the like. 
     The border  590  may be, for example, a printed border of a solid color or the border may include a decorative design. The border  590  delineates the edge of the writing surface  534  to help a user identify where the writing surface  534  ends and where the surrounding surface (e.g., the wall) begins. 
     Referring to  FIGS. 31A and 31B , the first and second screens  524 ,  578  are movable between an extended position ( FIG. 31A ) and a retracted position ( FIG. 31B ). The first screen  524  is movable to the extended position while the second screen  578  is retracted such that a user may write and/or draw on the first screen  524 . The second screen  578  may then be moved to the extended position to overlay at least a portion of the first screen  524  such that a user may continue to write and/or draw over or on top of the first screen  524 . In the illustrated construction, the handle  550  of the first screen  524  inhibits the second screen  578  from moving to the extended position when the first screen  524  is in the retracted position. However, in other constructions, the handle  550  may be configured to allow the second screen  578  to move to the extended position when the first screen  524  is in the retracted position. When the user is finished writing, the user may move the first and second screens  524 ,  578  to the retracted position to hide the writing on the screens  524 ,  578  or to make the marker screen assembly  520  more suitable for transport. 
     The above discussion and the accompanying figures describe various features and embodiments of the invention. However, those skilled in the art will understand that numerous other combinations and modifications of the above features and embodiments can be made while still falling within the scope of the invention. 
     Various features of the invention are set forth in the following claims.