Patent Publication Number: US-7913730-B2

Title: Modular raised wall paneling system and method of manufacture

Description:
RELATED PATENT APPLICATIONS 
     This application is a divisional application of U.S. Pat. No. 7,185,469, issued on Mar. 6, 2007, Ser. No. 10/389,497, filed on Mar. 14, 2003, entitled MODULAR RAISED WALL PANELING SYSTEM and has the same inventor in common. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a raised wall paneling system and more particularly, to a modular raised wall paneling system and method of manufacture that is economical, labor non-intensive, and can be easily constructed for a variety of room configurations and dimensions. 
     Conventionally, raised panel walls are often used for internal rooms of dwelling houses, office suites, and other similar arrangements, to enhance the appearance of a room. At one time, such walls were formed from solid wood sheets having raised panels that added to the aesthetic appeal of the wall. Unfortunately, the material cost of creating a solid wood wall is substantial and an extensive amount of labor is required to manufacture and install the wall. Accordingly, building contractors have looked for substituting conventional solid wood raised walls with more cost effective products. 
     As a substitute for conventional solid wood raised walls it has become common to form raised walls using preassembled raised paneling systems that are typically manufactured in panel sections formed from sheets of material such as particle board or medium density fiber board. Such panel sections can then be assembled together, usually at the location of installation, to form a wall having the appearance of a wall formed of solid wood. The raised panels and side portions of the wall are typically formed by cutting and assembling frame members into a raised panel member that is then secured to the panel section with nails, screws, or an equivalent mounting means. Such a method of manufacture, however, is still substantially expensive because it requires several precise machining and assembly operations. In addition, such raised panels also have a tendency to respond readily to the humidity and temperature conditions of the surrounding air by either contracting or expanding. This often results in causing panel separation thus reducing the overall aesthetic appeal of the paneled wall. 
     In recent years, installing a raised wall paneling system has also become popular for home improvement projects. Unfortunately, another problem associated with conventional preassembled raised wall paneling systems is that each system must be sized and cut to enable the individual panels to precisely fit along the wall on which it is to be installed. Further, such panels should fit together in such a manner as to minimize the formation of unsightly seams or joints between the individual panel sections. A raised wall paneling system must also be able to accommodate windows, doors and the like while providing an aesthetic appealing appearance. This requires a substantial amount of skilled carpentry labor to ensure the system&#39;s proper installation and fit. Accordingly, the installation requirements of conventional raised wall paneling systems are often beyond the ability of many individuals. 
     It is therefore apparent that there is a need for a raised wall paneling system that gives the appearance of solid wood paneling thereby enhancing the appearance of a room, that is relatively inexpensive, that can react to changes in climatic conditions without detracting from its aesthetic appearance, that can be easily sized to fit specific room geometry, and which is relatively easy to manufacture and install requiring a minimum amount of labor or required skill. A need also exist for a method of manufacturing and supplying a raised wall paneling system that is economical, produces a paneling system that precisely fits along the wall on which it is to be installed, minimizes unsightly seams, and can be easy installed with a minimum amount of labor and skill. 
     SUMMARY OF THE INVENTION 
     The present invention is a new and novel raised wall paneling system, and more specifically, the present invention is a new and novel modular raised wall paneling system and method of manufacture that is economical, labor non-intensive, and can be easily constructed for a variety of room configurations and dimensions. The modular raised wall paneling system of the present invention comprises a plurality of individual panel sections having a joint there between, wherein a panel section includes a recess portion creating the appearance of a raised panel. In a preferred embodiment of the invention the panel sections include along opposed longitudinal edges an interlocking means for interlocking the individual panel sections together. In a preferred embodiment of the invention, the interlocking means comprises a tongue and a groove, such that the panel sections can be disposed in parallel side-by-side mating relationship so that the tongue of one panel section is received in the groove of an adjacent panel section. 
     In another preferred embodiment of the invention the individual panel sections are secured together by an attaching means. 
     In another preferred embodiment of the invention the modular raised wall paneling system includes a horizontal rail and vertical stiles. 
     In another preferred embodiment of the invention the modular raised wall paneling system includes along opposed horizontal edges a second interlocking means for interlocking individual vertically aligned panel sections together. In a preferred embodiment of the invention, the second interlocking means comprises a tongue and a groove such that the panel sections can be disposed in parallel side-by-side mating relationship such that the tongue of one panel section is received in the groove of an adjacent panel section. 
     In another preferred embodiment of the invention the modular raised wall paneling system is formed from a group of materials consisting of pressed wood, particle board, medium density fiber board, plywood, laminated wood, and plastic. 
     In another preferred embodiment of the invention the modular raised wall paneling system includes instructions identifying the location of the individual panel sections in relation to each other. 
     In another preferred embodiment of the invention the modular raised wall paneling system includes a panel section having a milled recess portion. 
     In another preferred embodiment of the invention the modular raised wall paneling system is constructed by the method comprising the steps of measuring the room to be paneled, calculating the number and dimensions of panel sections for the modular raised wall system, and calculating the dimensions of each raised wall panel. 
     In another preferred embodiment of the invention the method of constructing the modular raised wall system includes the step of forming each raised wall panel by applying a milling process to the panel section. 
     In another preferred embodiment of the invention the method of constructing the modular raised wall system includes the step of forming a tongue and a groove along opposed lateral edges of each panel section. 
     In another preferred embodiment of the invention the method of constructing the modular raised wall system includes placing an order using the Internet and providing measurements of the room to be paneled. 
     In another preferred embodiment of the invention the method of constructing the modular raised wall system includes identifying each panel section and its relationship to the other panel sections forming the modular wall system. 
     These and other objects and advantages of the invention will be apparent from the following drawings and detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To provide a more complete understanding of the present invention and further features and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a partial perspective view of the modular raised wall paneling system of the present invention showing a plurality of individual panels mounted along a wall; 
         FIG. 2  is a front, top, and bottom views of a pair of individual panels forming the modular raised wall paneling system of  FIG. 1 ; 
         FIG. 3  is an exploded front, top, and bottom views of a pair of individual panels and a vertical end casing of the modular raised wall paneling system of  FIG. 1 ; 
         FIG. 4  is a front view of the pair of individual panels and the vertical end casing of  FIG. 3  shown in an assembled condition; 
         FIG. 5  is a top view taken along line  5 - 5  of  FIG. 3  illustrating a preferred interlocking means of the raised wall paneling system comprising a tongue and a groove formed along opposed longitudinal edges that form an abutting joint between individual wall panels; 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 3  illustrating the tongue and groove opposed longitudinal edges forming an abutting joint between individual wall panels; 
         FIG. 7  is an enlarged view of the attachment means of the raised wall paneling system of  FIG. 1  that is used for drawing, securing and holding the individual paneling sections together; 
         FIG. 8  is another enlarged view of the attachment means of  FIG. 7  showing placement within a slot; 
         FIG. 9  is a schematic representation of an apparatus for designing the modular raised wall paneling system of the present invention; 
         FIG. 10  is a flow diagram of a preferred embodiment of the apparatus for performing the method of designing a modular paneling system of the present invention having a computer system for implementing the system software incorporated therein; 
         FIG. 11  is a schematic representation showing the zoning for use in designing the modular raised wall paneling system of the present invention; 
         FIG. 12  is a perspective view of a computer controlled milling machine for performing the method of manufacturing the modular paneling system of the present invention; 
         FIG. 13  is a continuation of the flow diagram of  FIG. 10 ; 
         FIG. 14  is a side sectional view taken along section  14 - 14  of  FIG. 2  showing the recessed periphery of a raised wall panel; 
         FIG. 15  is a schematic representation of a horizontal spindle of the computer controlled milling machine of  FIG. 12 ; 
         FIG. 16  is a schematic representation of a vertical spindle of the computer controlled milling machine of  FIG. 12 ; 
         FIG. 17  is a schematic representation of a horizontal spindle of the computer controlled milling machine of  FIG. 12 ; 
         FIG. 18  is a side view of a section of the beveled portion of a raised wall panel being formed using prior art tooling; and 
         FIG. 19  is a perspective view of the beveled portion of a raised wall panel formed from the prior art tooling of  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a new and novel paneling system and more specifically to a modular raised wall paneling system and a method of manufacture. In describing the preferred embodiments of the invention, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
     Referring to  FIGS. 1 through 4 , the modular raised wall paneling system  100  of the present invention is shown having a plurality of individual panel sections  102  mounted along one or more surfaces such as a wall W or a ceiling C. As shown, each panel section  102  preferably extends from the floor F to the ceiling C. In a preferred embodiment of the invention, the modular raised wall paneling system  100  further includes a top rail  104  and a base rail  106  installed horizontally across the upper  105  and lower  107  edges respectively of individual panel sections  102 , and a first end stile  108  and a second end stile  110 . Other accessories can be provided, such as a decorative cap  112  and a shoe  114  installed horizontally across the upper and lower edges of the top rail  104  and the base rail  106  respectively, and a chair rail molding  116  that extends horizontally across the panel sections  102 . Preferably, the medium used in the manufacture of the individual panel sections  102  is a fiberboard due to its dimensional stability. It should be understood, however, that other materials such as pressed wood, particle board, plywood, laminated wood, plastic, or any other suitable material may also be used. The panel sections  102  are partially finished with an acrylic coat of paint or in a wood veneer. The rails  104 ,  106  and  116  and accessories are typically formed from wood, plastic, particle board, or can be formed from some other conventional material suitable for use for wall moldings. 
     As shown in  FIGS. 2 and 14 , each panel section  102  includes at least one raised wall panel  118  which preferably is generally rectangular in shape and comprises a planar face  120  and a recess periphery  122  having an inner step portion  124  and an outer step portion  126  and a planar portion  128  there between. Preferably, as shown, the planar portion  128  is sloped or beveled outwardly from the inner step portion  124  to the outer step portion  126  and together cooperate with the planar face  120  to give the appearance of a conventional solid wood raised wall panel. It should be understood that while the raised wall panel  118  is preferably rectangular in shape, other geometric shapes may also be utilized. 
     As illustrated in  FIGS. 3 through 6 , each individual panel section  102  includes along opposed vertically extending longitudinal edges an interlocking means  129 . In a preferred embodiment of the invention, the interlocking means  129  comprises a tongue  130  and a groove  132  such that the individual panel sections  102  can be placed in parallel side-by-side relationship where the tongue  130  of one panel section  102   a  is received in and mated in the groove  132  of an adjacent panel section  102   b . As shown, the first end stile  108  includes an outer butt end  134  for placing at the end or against a corner of the surface to be paneled and an inner groove end  136  that is adapted for mating with the tongue  130  of the first panel section  102 . The second end stile  110  includes an outer butt end  138  for placing at the other opposite end of the surface to the paneled and an inner tongue end  140  that is adapted for mating with the groove of the last panel section  102 . As shown, as assembled, the edges of tongue  130  of one panel section  102   a  is horizontally positioned such that when mated with the groove  132  of an adjacent panel section  102   b  the panel section  102   b  forms a vertical stile  142  that runs between the raised wall panels  118  and forms the outer seam  144  of a raised wall panel  118 . In this way, seams  144  formed between any two mated panel sections and between the end stiles and the corresponding panel sections will run along the outer edge of the raised wall panels and are therefore partially hidden or camouflaged thereby minimizing the appearance of the seams  144 . While the vertically extending longitudinal edges  145  are provided with an interlocking means  129 , such as a tongue or groove, it should be understood that the horizontally extending longitudinal edges  105  and  107  may also be provided with a second interlocking means (not shown), such as a tongue and groove, to allow additional panel sections to be placed vertically side-by-side relationship for paneling larger surfaces such as a room with a high ceiling. 
     As illustrated in  FIGS. 5 and 6 , in a preferred embodiment of the invention, the tongue  130  and the groove  132  of each panel section  102  are beveled thereby making them more durable and less susceptible to damage during shipping and installation. It should also be understood that by beveling the edges  146  of the tongue  130  and the groove  132 , results in a joint that is more rigid and stronger than a straight cut joint thereby reducing the necessity of having a wall stud to be positioned behind the joint. In addition, beveling the joint reduces the need to accurately align the tongue  130  with the groove  132  during installation thereby making assembly of the modular raised wall paneling system  100  significantly easier. 
     As illustrated in  FIGS. 4 ,  7  and  8 , in order to provide additional support, individual panel sections  102  are drawn and secured together by a plurality of attaching means  148 . In a preferred embodiment of the invention, as illustrated, the attachment means  148  comprises a conventional joint fastener, such as a ball and screw fastener sold by Knape &amp; Vogt as KV Deluxe Tite-Joint Fastener KV-516. As shown, the attachment means  148  is inserted within aligned slots  150  of adjacent panel sections  102  that are contoured for receiving the attachment means  148  such that when tightened the attachment means  148  operates to draw together, secure and hold the panel sections  102  together. It should be understood, that other types of attachment means may be utilized that can be inserted within slots contoured to receive the particular attachment means and which operate to draw together and secure the individual panel sections together. As shown in  FIG. 1 , the individual panel sections  102  can then be attached to a surface, such as a wall W or a ceiling C, by securing means (not shown) such as nails, screws, staples, glue, and the like. It should be understood that the securing means should be applied horizontally along the upper and lower edges of panel sections  102  where the rails are positioned such that the securing means can be hidden by the top rail  104 , base rail  106 , and chair rail  116 , respectively. The rails  104 ,  106  and  116 , as well as any decorative cap  112  and shoe  114  are preferably applied by glue. It should be understood, however, that other convention methods, such as the use of finishing nail or screws may also be used to attach the rails or other accessories to the panel sections  102 . 
     Referring to  FIGS. 1 ,  9  and  10 , a preferred embodiment of the apparatus  200  for manufacturing the modular raised wall paneling system  100  of the present invention is shown and comprises a visualization and modification device (VMSPD)  202  having a central processing unit  204  used to implement the system software  206  of the VMSPD  202 . The central processing unit  204  includes a memory  208  and may be electronically coupled to other devices, such as a suitable input device  210 , like a keypad, touch screen, mouse, cursor, voice recognition unit, or any other suitable input device that can accept information, and one or more suitable output devices  212 , such as a computer or electronic display device, printer, projection device, and the like. It should be understood that the VMSPD  202  can include any combination of the above components, or any number of different components, peripherals, and other devices. Preferably, the central processing unit  204  operates under the control of an operating system, such as the WINDOWS™ operating system developed by Microsoft Corporation or the Macintosh™ operating system developed by Apple Computer Corporation. It should be understood, however, that other operating systems could be utilized to implement the system software  206  of the VMSPD  202  of the present invention. 
     The system software  206  is a user or a computer-readable medium having user or computer-readable instructions for performing the method of manufacturing the raised wall paneling system  100  of the present invention. Preferably, the system software  206  is an interactive, menu and event driven system that uses prompt, dialog, and entry windows to guide a user to enter information. As used herein, the term “software” refers to any form of programmed machine-readable language or instructions (e.g., object code) that, when loaded or otherwise installed, provides operating instructions to a machine capable of reading those instructions, such as a computer. The system software  206  of the present invention can be stored or reside on, as well as be loaded or installed from, one or more floppy disks, CD ROM disks, hard disks or any other form of suitable non-volatile electronic storage media. The system software  206  can also be installed by downloading or other form of remote transmission, such as by using Local or Wide Area Network (LAN or WAN)-based, Internet-based, web-based or other remote downloading or transmission methods. 
     Referring to  FIG. 10  a flowchart illustrating the structured methodology and design of the system software  206  used for implementing the method of the present invention is shown. Referring also to  FIGS. 1 ,  2 ,  9  and  11 , upon entering the system software  206  (step  300 ), the system software  206  operates by directing the operator to enter the dimensions, preferably using the metric system, of the surface(s) to be paneled including the location and size of all door, window, and other openings (or surfaces to be paneled around) and jamb sizes of the wall or walls to be paneled by using the input device  210  of the VMSPD  202 . The system software  206  then operates (step  302 ) to break the surface(s) to be paneled into one or more zones, identified herein in this example as  152   a ,  152   b ,  152   c ,  152   d ,  152   e  and  152   f . Each zone is determined by the size of the raised wall panel  118  to be used on the individual panel section  102 . For example, in order to maintain the architectural integrity of the modular raised wall paneling system  100  and the overall appearance of the room, the preferred size of raised wall panels  154  and  156  positioned below and above a window WI, respectively, or a raised wall panel  158  above a door D, or raised wall panels  160  formed along a smaller section of the wall W may be smaller than the raised wall panels positioned along the remaining wall. Accordingly, in this example six zones would be identified, one zone  152   a  would be created covering the area to one side of the window WI, one zone  152   b  covering the area above the window WI, one zone  152   c  covering the area below the window WI, one zone  152   d  covering the area between the window WI and the door D, one zone  152   e  covering the area above the door D, and one zone  152   f  covering the area along between the door D and the edge of the wall W. The system software  206  then operates to calculate the number of equal sized panel sections for each zone (step  304 ). If two zones perpendicularly intersect, such as when two walls intersect, the system software  206  operates to subtract the thickness of the medium being used from the dimension from one of the intersecting panel sections to ensure that the appearance of the stile at the intersection will be consistent with all of the other stiles thereby maintaining the architectural integrity of the finished installed paneling system. 
     In a preferred embodiment of the invention, only the individual raised wall panels will vary in size while the widths of the rails and stiles will remain constant. Preferably, the number of wall panel sections is calculated based on the minimum number of wall panel sections required and the width of the medium. For example, standard sizes for panel medium is typically four-foot (4′ or 1.22 m) or five-foot (5′ or 1.52 m) in width and eight-feet (8′ or 2.44 m) or ten-feet (10′ or 3.05 m) in height. For a medium having a thickness of 0.75 inches (1.91 cm) and for a wall having a length of fourteen feet (14′ or 4.27 m) could be covered using four standard four-foot medium panels each being 3.5 feet (1.07 m) long or three standard five-foot medium panels each being 4.67 feet (1.42 m) long. 
     After the system software  206  has calculated the number of equal sized panel sections for each zone, the system software  206  then directs the operator (step  306 ) to either modify the selected zones and panel sizing (step  308 ) using the input device  210  or to accept the selected zones and panel sizing (step  310 ). If the sizing of the modular raised wall paneling system is to be modified or the desired individual panel sizes are to be modified, the modifications can be made to the sizing using conventional computer aided design methods or in the form of sizing modifications by inputting measurement information or from using previously supplied sizing information stored in the memory  208 . The system software  206  then operates to generate a new paneling system design (step  312 ). In a preferred embodiment of the invention, an image (not shown) is produced (step  314 ) showing the modular raised wall paneling system and displayed on the output device  212 . The operator can then accept the modified sizing (step  316 ) using the input device  210  or can make additional modifications. 
     After the operator has accepted the sizing and the appearance of the raised wall paneling system to be installed, the system software  206  directs (step  318 ) the operator to store the sizing information in the memory  208  of the VMSPD  202  or in a separate paneling storage bank, such as on one or more floppy disks, CD ROM disks, hard disks or any other form of suitable non-volatile electronic storage media (step  320 ), or to dump the sizing information (step  322 ). If the operator decides to dump the sizing information, the system software  206  directs the operator to either end the program (step  326 ) or to input new surface dimensions (step  308 ) and begin the process over. If the operator decides to store the sizing information, a final design can be stored and printed (step  328 ) using the output device  212  or another output device, such as a conventional printing device, at a remote location. 
     As shown in  FIGS. 9 ,  11 ,  12  and  13 , after the final design of the raised wall paneling system has been selected, the operator can then direct the system software  206  to transfer the information to a conventional numerically controlled cutting machine  400  (step  330 ). The cutting machine  400  of the present invention is shown comprising a stationary surface  402 ; a first tool head  404  and a second tool head  406  mounted to a control slide  408  for horizontally moving the tool heads  404  and  406  with respect to the stationary surface  402 ; a tool head support  410  for vertically moving the tool heads  404  and  406  with respect to the stationary surface  402 ; a horizontal spindle  412  mounted to the tool head  404 ; and a vertical spindle  414  mounted to the tool head  406 , and a numerical controller  416  for controlling the movements of the control slide  408  and the tool head support  410  to control the position of the spindles  412  and  414 . One such numerically controlled cutting machine is manufactured and sold by the Thermwood Corporation of Dale, Ind. After the numerically controlled cutting machine  400  has been provided with instructions from the central processing unit  204 , the individual panel sections are cut into their proper dimensions (step  332 ). The edges of the cut panel sections are then cut (step  334 ) with an interlocking means, as previously described, such that the individual panel sections when assembled can be secured together as previously described herein, and the slots for receiving the attachment means, as previously described, are formed. 
     After the edges of a panel section  102  have been cut with the interlocking means, the panel section  102  is placed in position to be milled (step  336 ). As shown in  FIGS. 2 ,  12  through  17 , depending on the particular stage of operation, the spindle used can be a horizontal spindle  412  ( FIG. 15 ) or one of several vertical spindles  414  ( FIGS. 16 and 17 ). As illustrated, the individual panel sections  102  are first milled (step  338 ) using the horizontal spindle  412  that operates to mill out the beveled portion  128  of the recess periphery  122  of each raised wall panel  118 . As shown in  FIGS. 18 and 19 , a recess periphery  122  cut area produced by a vertical spindle  418  will result in forming a relatively horizontal space  420  along the recess periphery  122 . Such spacing  420  is often undesirable and will often detract from the overall appearance of the raised wall paneling system  100 . It has been found that the use of a horizontal spindle will significantly reduce or eliminate the horizontal space  420  thereby enhancing the overall appearance of the assembled modular raised wall paneling system  100 . The inner step portion  124  and the outer step portion  126  of the raised wall panel  118  are then milled using a vertical spindle  414  (step  340 ). In order to reduce the rounding of the corners, a series of vertical spindles, such as shown in  FIGS. 16 and 17 , having sequentially reduced cutting diameters are used in overlapping cutting relationship to minimize the rounding of the corners and give the raised wall panel  118  the appearance of having square corners (step  342 ). The finished panel sections  102 , together with assembly instructions (not shown) and all previously described attachment means and accessories, can then be shipped to the customer location (step  342 ) for assembly and installation. 
     In another preferred embodiment of the invention, the method of manufacturing a raised wall paneling system further comprising the step of selecting the particular paneling system to be manufactured and storing the sizing information in the memory  208  of the VMSPD  202  which can be done from a remote location  220  ( FIG. 9 ) such as by the customer using an Internet based input system. 
     It should now be understood that the raised wall paneling system and the method of manufacture of the present invention permits manufactures to allow for flexibility and customization. For example, a typical fourteen-foot (4.27 m) wall could be laid out with four panels having a width of 3½ feet each. The system software of the present invention, however, allows the operator to design a paneling system having five panels; one panel of four feet, two panels of three feet each, and two panels of two feet each. 
     It should also be understood that customers can also input room dimensions, such as by means of the Internet. Based on the room or wall measurements and location of all doors, windows, and the like, a paneling system can be manufactured as described herein above. The modular raised wall paneling system is then sent to the customer. The customer, using the instructions that identify each panel section and their relationship to one and another can easily constructed the modular raised wall paneling system. It should now be apparent to those skilled in the art that the present invention provides a modular raised wall paneling system that is relatively easy to manufacture and install and requires a minimum amount of labor or required skill. 
     It should also be understood that unlike manufacturing processes that use only vertical spindles where the cut on one side of the vortex is also cut on the other side, the use of a horizontal spindle in the manufacture of the modular raised wall paneling system of the present invention allows the use of different spindles to create a substantial number of panel peripheries having various profiles. 
     Accordingly the modular raised wall paneling system and the method of manufacture of the present invention provides an apparatus and a method of manufacture that easily and economically provides a modular raised wall paneling system that has the appearance of a conventional solid wood systems, that enhances the appearance of a surface, such as a wall or ceiling, that is relatively inexpensive, that can react to changes in climatic conditions without detracting from its aesthetic appearance, that can be easily sized to fit specific room geometry, and which is relatively easy to manufacture and install requiring a minimum amount of labor or required skill. It should also now be apparent that the method of manufacturing and supplying the modular raised wall paneling system of the present invention is economical, produces a paneling system that precisely fits along the surface on which it is to be installed, minimizes unsightly seams, and can be easy installed with a minimum amount of labor and skill. 
     While the method and apparatus described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to the precise method and apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.