A modular wall panel system in which individual panels are constructed with a lightweight aluminum frame. In a preferred embodiment, the frame is substantially filled with a foam core material and decorative display surfaces are affixed to opposite sides thereof. One edge of each panel contains a plurality of ball-shaped connector pins, while the opposite edge has a plurality of connector slots having a diamond configuration. A similar panel placed adjacent to the first panel may be mated thereto by engagement of the connector pins with respective connector slots in the other panel. The pins/slots are shaped and sized so that the connector pin may enter/exit the connector slot at a wide region thereof but not in the apex region thereof. Secure coupling with fast assembly/disassembly is thereby achieved, without tools or detachable components.

BACKGROUND OF THE INVENTION 
     The present invention relates generally to a modular wall panel system and, more particularly, to a modular wall panel system which allows for interconnection of adjacent panels without the need for tools and/or detachable parts. 
     Exhibits and displays have found wide usage in today's business and marketing environment, particularly with respect to businesses that participate in conventions, trade shows, seminars and other such events. Also, static or mobile exhibits and displays are used in places such as museums and building lobbies. Due to the nature of these applications, such exhibits and displays are typically assembled and disassembled by a limited number of persons within a limited period of time at the exhibition site. Thus, a basic design requirement of such portable display devices is a minimization of weight and structural complexity, coupled with a maximization of durability and aesthetic appearance. In the extremely competitive sales environments in which trade show exhibits are commonly used, the owner is usually not willing to sacrifice durability or aesthetic appearance. 
     The conventional tradeshow exhibit is a semi-permanent reusable display designed for long-term usage. These are generally custom fabricated, and are durable, allowing for frequent reuse. For transport, the displays must be broken down into numerous component parts, which are then crated for shipping. In a typical installation, such assemblies must be received at a proper loading dock and assembled by the exhibit site personnel. Frequently, only venue employees are allowed to unload and construct the exhibit display. This can dramatically increase the costs of setting up a large exhibit. Such costs are based upon the manpower required to unload and assemble the exhibit display and the time required for doing so Light, easily assembled panels minimize such costs. 
     There is a need for lightweight, custom designed, durable, aesthetic display systems that may be easily assembled and disassembled at exhibit trade shows. The present invention is directed toward meeting this need. 
     SUMMARY OF THE INVENTION 
     The present invention provides a modular wall panel construction in which one edge of a panel contains a plurality of tapered connector pins and the opposite edge has a plurality of tapered connector slots which in certain embodiments have a “diamond” or a “V” configuration. Two such panels may be interconnected by engagement of the connector pins of one panel with respective connector slots in the other panel. The pins/slots are shaped and sized so as to cooperate to draw adjacent panels together edgewise as the panels are interconnected. Secure coupling with fast assembly/disassembly is thereby achieved, without tools or detachable components. 
     Other aspects of the present invention will be apparent from the following descriptions of preferred embodiments with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of an embodiment of a panel of the present invention. 
     FIG. 2 is a cross sectional view of the panel of FIG. 1 taken along plane  2 — 2  and viewed in the direction of the arrows. 
     FIG. 3 is a top plan view of the panel of FIG.  1 . 
     FIG. 4 is a left side elevational view of the panel of FIG.  1 . 
     FIG. 5 is an enlarged front elevational view of a connector pin of the panel of FIG.  1 . 
     FIG. 6 is an enlarged left side elevational view of a connector slot of the panel of FIG.  1 . 
     FIG. 7 is an enlarged front elevational view of the connector slot of FIG.  6 . 
     FIG. 8 is an enlarged front elevational view of a locator pin of the panel of FIG.  1 . 
     FIG. 9 is an enlarged left side elevational view of a locator slot of the panel of FIG.  1 . 
     FIG. 10 is an enlarged front elevational view of the locator slot of FIG.  9 . 
     FIG. 11 is an enlarged elevational view of the connector slot of FIG. 6 in which the connector pin of FIG. 5 is received in the locked position. 
     FIG. 12 is an elevational view of an embodiment of the present invention, showing connection between adjacent display panels. 
     FIG. 13 is a perspective view of another embodiment of a panel of the present invention. 
     FIG. 14 is a front elevational view of an embodiment of a male adapter plate for use with the panel of FIG.  13 . 
     FIG. 15 is a side elevational view of the male adapter plate of FIG.  14 . 
     FIG. 16 is a front elevational view of an embodiment of a female adapter plate for use with the panel of FIG.  13 . 
     FIG. 17 is a side elevational view of the female adapter plate of FIG.  15 . 
     FIG. 18 is an alternative embodiment of the connector slot of the left side of the panel of FIG. 1 or the female adapter plate of FIG.  16 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
     The present invention provides a modular panel wall system having individual wall panels that are light enough to be handled by a single person. The panels are approximately one half the thickness of conventional  4 ″ thick panels, which saves space during shipping. Even so, the panels of the present invention are rigid, aesthetic and durable. Furthermore, the modular wall panels of the present invention include a system for interconnecting adjacent panels that does not require any tools or separate parts to effect the connection. 
     Referring to FIG. 1, there is illustrated an embodiment of a wall panel of the present invention, indicated generally at  10 . Each of the panels  10  has a frame formed from vertical support members  12  and horizontal support members  14 . Both the vertical support members  12  and the horizontal support members  14  are formed from aluminum. In a preferred embodiment, the vertical support members  12  are formed from substantially square aluminum tubing having dimensions of 2″×2″. Also in a preferred embodiment, the horizontal support members  14  are formed from 2″×3″ aluminum U-channel members. The horizontal cross members  14  are affixed to the vertical support members  12  by any convenient means, such as by welding. The use of aluminum in the frame construction of the modular panel  10  results in a modular panel that is light and thin, yet strong and rigid. The horizontal support members  14  are formed from U-channel material rather than from full tubes in order to further decrease the weight of the finished unit and facilitate their use as wire channels for carrying electrical wires associated with the display. The placement of the horizontal support members  14  is illustrated in the cross sectional view of FIG.  2 . The configuration of the vertical support members  12  is more clearly illustrated in the plan view of FIG.  3 . 
     The right side of each modular wall panel  10  is provided with two tapered pins  16 , specifically, ball connector pins, located near the upper and lower ends thereof. Furthermore, a locator pin  18  is coupled to the right side of the wall panel  10  substantially in the middle of the right hand vertical support member  12 . Referring to FIG. 4, each wall panel  10  further includes two connector slots  20  formed in the left hand vertical support member  12  thereof at generally the same vertical locations as the ball connector pins  16 . A locator slot  22  is formed in the left hand vertical support member  12  at the same vertical location as the locator pin  18 . As described in greater detail hereinbelow, and as illustrated generally in FIG. 12, the ball connector pins  16  are designed to fit in locking engagement with the connector slots  20  of an adjacent wall panel  10 . In a typical case where adjacent panels are designed to rest directly on a level surface, the nominal position of a given pin is offset vertically from the center of a corresponding slot in order to facilitate such locking engagement when the panels are interconnected. Likewise, the locator pins  18  are designed to engage the locator slot  22  of an adjacent wall panel  10 , although the locator pin does not fit in locking engagement with the locator slot. The use of the pins and complementary slots in the embodiment of the present invention allows for adjacent wall panels  10  to be coupled to one another without the use of any tools and without requiring separate parts which may become separated from the wall panels  10 . Furthermore, the connector pin/connector slot arrangement of the present invention allows for extremely quick assembly and disassembly of the exhibit display, dramatically reducing the costs associated with these operations. 
     With reference to FIGS. 5-7 and  11 , the ball connector pin  16  and connector slot  20  engagement is illustrated in greater detail. The ball connector pin  16  is preferably formed from an aluminum spherical ball  24  and an aluminum spacer  26  that is generally disk shaped. One side of spacer  26  is flat to engage vertical support member  12  and the other side is concave to engage and mate with the surface of the spherical ball  24 . The ball  24  and spacer  26  each have a central bore  28  therethrough to receive and accommodate an alien head machine screw  30  that extends diametrically through the ball  24  and through the center of the spacer  26 . Ball connector pin  16  is joined to the vertical support member  12  by allen head machine screw  30  threadingly engaging a threaded insert  32  that is held in the vertical support member  12  by an interference fit with a mounting hole  34  formed for this purpose. The largest exterior dimension of the ball connector pin  16  is the diameter of the spherical ball  24 . The thickness of spacer  26  along the axis of the pin is about equal to the wall thickness of the vertical support member  12  having connector slot  20 . 
     The connector slot  20  is a tapered slot, specifically, a diamond-shaped slot, comprised of combined upper and lower triangular openings  36  joined at their bases and each defined by a pair of substantially straight side walls  40 , 42  and  44 , 46 , respectively, that converge toward oppositely extending upper and lower apexes  48 ,  50 . The center width of the diamond slot  20  is chosen to be larger than the diameter of the spherical ball  24  of the ball connector pin  16 . The ball connector pin  16  may be inserted through the center region of the diamond connector slot  20  until the spherical ball connector pin  16  lies substantially within the vertical support member  12 . At this point the ball connector pin  16  may be slid toward the upper or lower apexes  48 ,  50  wherein the spherical ball  24  of connector pin  16  is thereby locked within the connector slot  20 . If, for example, the pin in a first panel is nominally positioned below the center of its corresponding slot in an adjacent panel, the first panel is raised to allow insertion of the pin into the slot of the adjacent panel and the first panel is then lowered whereby the pin slides toward the lower apex  50 . Because the diameter of the spherical ball  24  of the ball connector pin  16  is larger than the converging width of the slot  20  toward the apexes  48 ,  50 , the ball connector pin  16  is prevented from exiting the connector slot  20  when it is arranged at either the upper or lower portion of slot  20 . Thus, the two adjacent wall panels  10  are effectively locked together once the ball connector pin  16  has been properly inserted into the connector slot  20 . FIG. 11 shows the position of the spherical ball  24  relative to connector slot  20  in the unlocked position (phantom lines) and the locked position (solid lines). 
     The spherical surface of ball  24 , adjacent spacer  26 , that faces vertical support member  12  diverges therefrom to form a cam surface that can engage the converging side walls  40 , 42  or  44 , 46  of connector slot  20  and draw adjacent panels  10  together as connector pin  16  is moved toward one apex  48  or the other apex  50  of slot  20 . Conversely, the spherical surface of ball  24 , adjacent spacer  26 , that faces vertical support member  12  can be said to taper toward support member  12 . The spherically curved surface of ball  24  interacting with the V-shape of one end of slot  20  causes a variable taper or wedging action that allows for easy initial alignment and engagement of the connector pin  16  and connector slot  20 , followed by a tight wedging action to hold adjacent panels  10  together. The angle of divergence of the spherical surface of ball  24  relative to vertical support member  12  decreases in the direction toward support member  12 , causing an increase in the wedging force against the side walls  40 , 42  or  44 , 46 . 
     Provision of mating ball connector pins  16 /connector slots  20  near the top and bottom of each modular wall panel  10  insures the panels  10  will be rigidly coupled together. Because both the ball connector pin  16  and the connector slot  20  are formed from similar aluminum materials, there is little if any appreciable wear on either member, virtually insuring the connector system of the present invention will outlast the useful life of the modular wall panel  10 . 
     As best illustrated in FIGS. 8-10, the locator pin  18  is formed from a generally cylindrical member  52  which is attached to the vertical support member  12  by an alien head machine screw  54 . The screw  54  threadingly engages a threaded insert  56  which is maintained in the vertical support member  12  by an interference fit with a mounting hole  58  formed therein for this purpose. The locator pin  18  has a constant diameter in a first portion  60  from its root through substantially about one half of its entire length, followed by a frusto-conical portion  62  that converges toward the free end of pin  18 . Furthermore, the locator slot  22  has substantially the same width throughout its entire length. The width of the locator slot  22  is chosen to be slightly larger than the width of the cylindrical portion  60  of the locator pin  18 . Therefore, the engagement of the locator pin  18  with the locator slot  22  does not result in any locking engagement between adjacent wall panels  10 . Rather, the locator pin  18 /locator slot  22  combination is provided merely as an alignment guide which facilitates the proper mating of the two ball connector pins  16  with their respective connector slots  20 . 
     It will be appreciated by those skilled in the art that the use of the specially shaped ball connector pin  16  and the connector slot  20  having a diamond shape allows for assembly and disassembly of adjacent wall panels  10 . For example, once the wall panels  40  are assembled, disassembly of the panels requires that one panel be raised vertically relative to its adjacent neighbor so that the ball connector pins  16  may be aligned with the wide center portion of the diamond connector slots  20  and removed therefrom. 
     As an alternative construction of panel  10 , another embodiment is formed from the same frame construction as the first embodiment wall panel  10 , and further includes the same ball connector pin  16 /connector slot  20  and locator pin  18 /locator slot  22  configuration. However, the spaces between adjacent horizontal support members  14  in the wall panel  10  are filled with 2″ thick cellulose foam material. The sections of foam are sized to substantially completely fill the space within the frame of the modular panel  10 , with the exception that the U-channels within the horizontal support members  14  remain unfilled. Both sides of the modular panel  10  are then covered with a decorative laminate material, such as plastic laminate commonly known in the art and manufactured by Formica®, Wilsonart®, etc. The outer laminate is coupled to the foam and/or frame of the modular panel  10  by any convenient means, such as a spray adhesive. 
     Because of the low density and high strength of the cellulose foam material, its addition to the structure of the modular panel  10  adds essentially no weight to the finished structure, however, it is very effective in providing rigidity to the entire structure. The foam material is especially useful in preventing deformation of the laminate material when subjected to forces perpendicular to its surface. Optionally, an elongate hole may be cut entirely through the modular panel  10  in order to provide a convenient hand hold for carrying the modular panel  10 . Because the modular panel  10  is light enough to be carried with one hand, the positioning of the hole substantially in the center of the modular panel  10  facilitates lifting and carrying of the panel. It will be appreciated by those skilled in the art that the hole will not be seen in the final constructed exhibit display if graphics or other materials are mounted onto the modular panel  10 , as is usually the case. 
     Referring now to FIGS. 13-17, there is illustrated an alternative embodiment of the present invention that is particularly suited for adapting a typical wood panel to utilize the ball connector pin and diamond connector slot arrangement discussed above with respect to panel  10 . FIG. 13 shows a typical nominal 1″×4″(¾″×3 ⅝″ actual dimensions) wood frame member  70  that would comprise one vertical support member of a typical wood panel. Such a panel can be adapted to incorporate the present invention by routing the face of the wood frame member  70  to form a recessed channel  72  preferably about 2″ wide, ⅛″ deep, and the height of the panel. A male adapter plate  74  or a female adapter plate  76 , either having a length substantially the same as the height of the panel, can be received and affixed within the recessed channel  72  so that the adapter plate  74  or  76  is flush with the original surface of frame member  70 . To effect this, the recessed channel  72  is routed to a depth substantially equal to the thickness of the adapter plate  74  or  76 . 
     With particular reference to FIGS. 14-15, a ⅛″×2″ male adapter plate  74  is shown. Connector pins  16   a  and locator pin  18   a  are affixed to adapter plate  74  in the same manner and in the same locations that connector pins  16  and  18  are affixed to vertical support member  12  as described above. In their configuration and construction, and manner of attachment to adapter plate  74 , connector pins  16   a  and locator pin  18   a  are substantially identical to the previously described connector pins  16  and locator pin  18 . 
     Referring now to FIGS. 16-17, a ⅛″×2″ female adapter plate  76  is shown. Connector slots  20   a  and locator slot  22   a  are formed in adapter plate  76  in the same manner and in the same locations that connector slots  20  and locator slot  22  are formed in vertical support member  12  as described above. In their configuration and construction, connector slots  20   a  and locator slot  22   a  are substantially identical to the previously described connector slots  20  and locator slot  22  in vertical support member  12 . Referring again to FIG. 13, because female, adapter plate  76  is backed by wood frame member  70 , recesses  78  are routed in the channel  72  of frame member  70  and aligned with connector slots  20   a  and locator slot  22   a  to provide clearance for the connector pins  16   a  and locator pin  18   a  to be received through female adapter plate  76 . 
     As shown in FIG. 18, an alternative embodiment of the present invention is shown that can be made substantially identical to any of the previously described embodiments except that the connector slots  20   b  are V-shaped at only one end, the opposite end of the slot being any shape that permits the ball connector pin  16  to pass through. The V-shaped end of the connector slot can be oriented upwardly or downwardly. If the V-shaped end of slot  20   b  is oriented downwardly as shown in FIG. 18, wherein the V-shaped end appears as an upright “V”, then the panel having the male connector pins  16   a  should be lifted relative to the other panel, the pins should be passed through the connector slots, and the panel with the connector pins  16   a  should be lowered to lock the panels together. If the V-shaped end of slot  20   b  is oriented upwardly, then the panel having the female connector slots  20   b  must be lifted relative to the other panel, the pins passed through the connector slots  20   b , and the first panel with the connector slots  20   b  should be lowered to lock the panels together. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.