Abstract:
An adjustable display panel having one or more individual sign elements slidably mounted between partitioning elements attached laterally to the frame. In one embodiment, a plurality of partitioning elements are magnetically attached to the frame using a series of apertures in the frame. The partitioning elements each include a sliding track or groove for slidably receiving one edge of the sign elements therein. A removable stop element is provided on at least one side of the frame to permit easy access to the sign elements in order to facilitate modification or replacement thereof. The sign elements of the present invention further comprise a front and rear portion, these portions being separable from one another. The front portion of the sign element, which contains graphic images or writing, may be separated from the rear portion and replaced. Additionally, the rear portion of each sign element includes one or more pockets having alphanumeric inserts which are readable through apertures in the front portion of the sign element, these inserts also being replaceable.

Description:
This is a continuation of applicant Ser. No. 08/984,439, filed Dec. 3, 1997 now U.S. Pat. No. 6,003,258. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to signs and more particularly, to an improved, adjustable display panel for back-lighted signs. 
     2. Description of the Related Art 
     Back-lighted signs are frequently used for advertising and promotion. Generally, in a back-lighted sign, an opaque message and/or picture is secured within a display panel. The display panel is typically mounted to a housing which includes a front wall, a rear wall, a top wall, a bottom wall and two side walls, wherein the top, bottom and side walls are peripherally joined to the front and rear walls, thereby defining a cavity within the housing. The front wall typically includes an aperture therein so that a light mounted within the cavity may shine through the aperture and illuminate a display panel attached to the front wall. The light illuminates the display panel and accentuates the message/picture on the display panel during the day and illuminates the message/picture at night. 
     Back-lighted signs, of the type described above, are typically found above counters in fast food restaurants. Often, such signs consist of a number of display panels with each panel displaying a different category of menu items and corresponding prices. For example, one panel may list hot sandwiches, with another panel for cold sandwiches, and yet another panel may list beverages and desserts. A display panel may also display a photographic reproduction of a food item being offered for sale in order to create customer interest. 
     Because display areas vary from restaurant to restaurant, and because of a need to create a distinctive appearing sign for different restaurants, modular sign systems have been devised. Such sign systems are typically created by attaching side-by-side a number of square, or rectangular, sign modules, each having a housing which contains lightbulbs for illuminating a translucent display panel attached to a front wall of the housing. Such rectangular modules can be combined horizontally or vertically, or in a two-dimensional array to form different sized and shaped sign assemblies. An example of such a modular sign system is disclosed in U.S. Pat. No. 5,379,540 to Howard, entitled “MODULAR SIGN SYSTEM.” 
     However, even with the above-described modular sign system, within a single given sign module, the display cannot easily be changed. Typically, within each display panel a specified number of image slides and/or photographic gels (referred to as “sign elements” herein) are inserted into a frame which surrounds a specified number of display windows, each configured to hold an individual sign element. For each of these display panels, the number of display windows and the size of each display window is fixed, or at the very least, extremely cumbersome to alter. Therefore, within a single given sign module, the number of items that may be displayed is not easily changed. Additionally, if one desires to change the size of a particular sign element, the old display panel must be replaced by a new display panel having a display window which matches the size of the desired sign element, or the frame of the display panel must be completely dismantled and reconfigured to provide the appropriately sized display window. These prior art display panels are not designed and constructed to be altered after the first time they have been assembled. Therefore, changing the configuration of the display windows within these display panels is tedious and time consuming. 
     One example of a prior art display panel is illustrated and disclosed in U.S. Pat. No. 4,277,904 to Leuthesser, entitled, “Back Lighted Sign Frame.” Leuthesser discloses a frame which surrounds a specified number of display windows, each display window capable of displaying a desired advertisement or other image therein. Multiple display windows may be created by dividing a particular display window with a partitioning member. However, once this display panel is created, it is not designed to be altered. Leuthesser discloses that each partition member is secured to the frame by means of tabs which extend longitudinally outwardly from each end of the partitioning member to be inserted into slots located on the frame. Leuthesser further discloses “suitable glue or other adhesive applied to the tabs to secure the [partitioning] member in the proper position . . .” However, even without glue or adhesive, in order to remove a particular partitioning member from the frame of the display panel disclosed by Leuthesser, one must flex and/or bend the partitioning member so as to dislodge the tabs attached to the ends of the partitioning member from their respective slots. This process often results in bent, broken, or otherwise damaged partitioning members and, additionally, is a clumsy and tedious process to undertake. Furthermore, the process of removing the partitioning members sometimes causes damage to the peripheral frame itself. 
     Therefore, prior art display panels do not provide a fully satisfactory method or system for adjusting the display panel so as to receive and display different sizes and/or numbers of sign elements. Therefore, there is a need to provide an adjustable display panel which may be quickly and easily modified so as to be able to accommodate different sizes and/or numbers of sign elements, as menu items change, for example. 
     Another deficiency of prior art display panels relates to the sign elements themselves. These sign elements are typically sheets of plastic material which are die cut and stamped into a desired geometirc configuration and have printed onto them a desired logo, name, message, etc. The sign elements are typically translucent such that they may be illuminated by a light source which shines light onto the backside of the sign element. Prior art sign elements typically consist of a front piece which is a rectangular-shaped plastic sheet having an image printed thereon. The front piece is permanently attached to a back piece which is a congruently shaped plastic sheet typically having a white, or off-white, color. Typically, the front piece includes multiple windows cut therein for allowing alphanumeric characters to be displayed therethrough. Pockets are formed between the first and second pieces at positions corresponding to the windows cut in the front piece. The pockets are typically formed by placing strips of double-sided adhesive tape between the front piece and back piece such that a pocket is defined between two adjacent strips which are laterally positioned across the width of the front and back pieces. The thickness of the double sided adhesive tape and the space between adjacent strips define the geometry of a respective pocket. 
     In order to display a price for a menu item, for example, numerical inserts are inserted into the pockets, and each numeral printed on an insert is visible through a respective window cut in the front piece. If the price of that particular menu item is changed, it is a relatively simple matter to replace the numerical inserts with new numerical inserts. However, if a new menu item, altogether, is desired to be displayed within a particular display window, the entire sign element which displays the old menu item must be replaced with a new sign element which illustrates the new menu item. This is not cost effective because both the front and back pieces of the sign element must be discarded, and additionally, the pockets formed between the front and back pieces are also wasted. Although the formation of the pockets is not expensive in terms of materials required, it does require extra manufacturing time and processing to form the pockets, which significantly adds to the manufacturing cost for each sign element. On the other hand, the printing and cutting of only the front piece is a relatively simple process and may be performed automatically by any one of a number of well-known printing machines. 
     Therefore, when a sign element is to be changed, it is desirable to be able to replace only the front piece of the sign element while retaining the back piece and the pockets for further use. This would not only decrease the amount of wasted materials (e.g., plastic sheeting) to less than one half of previous amounts, but, additionally, would save a significant amount of manufacturing steps and processing time which would otherwise be required to form pockets between the front and back pieces of a sign element. 
     SUMMARY OF THE INVENTION 
     The invention addresses the above and other needs by providing an adjustable display panel assembly in which a display window may be easily and adjustably partitioned into various desired configurations so as to accommodate a desired number of sign elements of varying sizes and shapes. Therefore, the display panel assembly of the invention may be easily and repeatedly modified to provide different configurations of displays such that new messages, menu items, images, etc. of varying sizes and dimensions may be implemented in the display panel assembly, without changing the overall size of the display panel. Additionally, the invention provides an improved sign element to be used in the adjustable display panel, wherein a front piece is removably attached to a back piece, such that when an old menu item, for example, is to be replaced with a new one, only the front piece of the sign element need be replaced. 
     In a first aspect of the invention, an improved display panel having a frame and adjustable partitioning elements is provided. In one embodiment, the frame is of a unitary construction having a series of apertures located longitudinally therein, and constructed of a ferrous material such that magnet elements located on each of the aforementioned partitioning elements are received by and fit within respective apertures in the frame, the magnet elements being attracted to the ferrous frame. Individual sign elements are received within grooves or tracks located on each of the partitioning elements such that each individual sign element may slide in and out of the display panel, thereby facilitating easy removal and alteration. The partitioning elements may also be easily moved to other apertures within the frame to accommodate sign elements of varying sizes. 
     In a second aspect of the invention, an improved display panel cover is disclosed which is substantially conformal with the display panel frame and which allows rapid removal and reattachment. In one embodiment, the cover is fabricated from a transparent, flexible material sized to fit within a recess in the aforementioned frame. The cover further includes a plurality of magnetic strips around its periphery which allow the cover to be held in a fixed position relative to the ferrous frame, yet the same time be easily removed. 
     In a third aspect of the invention, an improved sign element is disclosed for use within the display panel described herein, or other types of backlighted display panels requiring individual sign elements. In one embodiment, the sign element includes a front piece having a window cut therein, and a substantially transparent back piece with an insert pocket for holding an alphanumeric insert which shows through the window in the front piece when the front and back pieces are mated together. The front and back pieces are removably mounted to one another such that both the front piece (typically carrying an image or lettering next to the window) and the insert may be readily removed and altered or replaced. 
     In a fourth aspect of the invention, methods of fabricating the aforementioned display panel, removable cover, and sign elements are also disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a front view of one embodiment of a display panel assembly in accordance with the invention. 
     FIG. 2 is a perspective view of the display panel assembly of FIG. 1 as it is being attached to a housing for a back-lighted sign system having a light source for illuminating the panel display attached to a front wall of the housing. 
     FIG. 3A illustrates a top view of a die-cut piece of sheet metal which forms the frame of the display panel of FIG. 1 in accordance with one embodiment of the invention. 
     FIG. 3B illustrates the die-cut piece of sheet metal of FIG. 3A after it has been bent and/or folded to form desired peripheral flanged edges in accordance with one embodiment of the invention. 
     FIG. 4 illustrates a top view of the frame formed as shown in FIG. 3B after thin strips of steel sheeting have been attached to the internal peripheral ledges of the frame in accordance with one embodiment of the invention. 
     FIG. 5 illustrates a front view of a transparent cover panel which mates with the frame of FIG. 4 in accordance with one embodiment of the invention. 
     FIG. 6 illustrates a perspective view of the transparent cover panel of FIG. 5 as it is being attached to the frame of FIG.  4 . 
     FIG. 7 illustrates a back view of the transparent cover panel of FIG. 5 which illustrates magnetic strips attached to peripheral areas of the transparent cover panel so as to magnetically attach the transparent cover panel to the steel strips which are attached to the frame of FIG.  4 . 
     FIG. 8 illustrates a top view of the transparent cover panel after it has been attached flushed with the frame of FIG. 4 in accordance with one embodiment of the invention. 
     FIG. 9 is a back-side view of the frame assembly of FIG. 4 in accordance with one embodiment of the invention. 
     FIG. 10 is a top view, taken along lines  10 — 10  of FIG. 9, of the frame assembly of FIG.  9 . 
     FIG. 11 is a cross-sectional, side view, taken along lines  11 — 11 , of the frame assembly of FIG.  9 . 
     FIG. 12 is the cross-sectional, side view of FIG. 11, additionally having a slide, or photo gel, positioned within channels formed by top and bottom retention members attached to the back-side of the frame, in accordance with one embodiment of the invention. 
     FIG. 13 is a back-side view of the display panel assembly of FIG. 12 having a photo gel positioned within the assembly and locking strips attached to the back-side of the frame in order to lock the photo gel in position within the assembly, in accordance with one embodiment of the invention. 
     FIG. 14 illustrates a front view of the display panel assembly of FIG. 13, having a photo gel of fast-foot menu items displayed therein, in accordance with one embodiment of the invention. 
     FIG. 15 is a back-side view of an adjustable display panel assembly in accordance with one embodiment of the invention. 
     FIG. 16 illustrates a side view, when looking toward the direction of line  16 — 16  of FIG. 15, of two partitioning bars having a slide, or photo gel, positioned within respective channels of each partitioning bar, in accordance with one embodiment of the invention. 
     FIG. 17 illustrates an elevated side view of a partitioning bar in accordance with one embodiment of the invention. 
     FIG. 18 illustrates a close-up, elevated, side view of the mating configuration of one end of the partitioning bar of FIG. 17 with the frame assembly of the panel display assembly of FIG. 15, in accordance with one embodiment of the invention. 
     FIG. 19 illustrates a top view of a locking strip as it is positioned onto the frame of the display panel assembly, in accordance with one embodiment of the invention. 
     FIG. 20 illustrates a cross-sectional side view, taken along lines  20 — 20 , of the locking strip of FIG. 19 as it is attached to the frame in order to prevent a slide from sliding out of the panel display, in accordance with one embodiment of the invention. 
     FIG. 21 illustrates an improved sign element which may be used in the display panel, in accordance with one embodiment of the invention. 
     FIG. 22 illustrates double-sided adhesive strips which are attached to a back piece of the sign element of FIG. 21, in order to form pockets, in accordance with one embodiment of the invention. 
     FIG. 23 illustrates a piece of die-cut plastic sheeting, having windows cut therein, for forming pockets which are attached to the back piece of the slide assembly of FIG.  21 . 
     FIG. 24 shows the completed pocket assembly after the die-cut plastic sheeting of FIG. 23 has been attached to the back piece of the sign element by means of the double-sided adhesive strips of FIG. 22, in accordance with one embodiment of the invention. 
     FIG. 25 illustrates a top view, taken along lines  25 — 25 , of the pocket assembly of FIG.  24 . 
     FIG. 26 illustrates numerical inserts being inserted into the pockets formed on the back piece of the sign element of FIG. 21, in accordance with one embodiment of the invention. 
     FIG. 27 illustrates a front view of the sign element of FIG. 21 after the front piece has been attached to the back piece and numerical inserts have been inserted into respective pockets formed on the back piece, in accordance with one embodiment of the invention. 
     FIG. 28 illustrates a portion of a sign element where alphanumeric inserts are displayed through windows cut in a front piece of the sign element and wherein light radiates outwardly from the peripheral edges of the windows so as to create a “halo” effect. 
     FIG. 29 illustrates a size relationship between a front window cut into a front piece of a sign element and a pocket window cut into a pocket attached to a back piece of the sign element, the size relationship being configured to eliminate the “halo” effect illustrated in FIG. 28, in accordance with one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention is described in detail below with reference to the Figures, wherein like elements are referenced with like numerals throughout. 
     Referring to FIG. 1, a display panel assembly  100 , in accordance with one embodiment of the invention, is illustrated. The display panel  100  includes a peripheral frame  102  which provides a support structure that surrounds sign elements  104 . The sign elements  104  are commonly called slides, or photo gels, and are typically made from a translucent plastic which when radiated with light from a light source from behind, provides an illuminated advertisement or message which is quite aesthetically pleasing. The sign elements  104  typically include lettering and/or numbers  106  which are either printed or die-cut, or stamped, into the sign element  104 . When illuminated from behind, these alphanumeric characters  106  typically radiate a light of a different color from that of the rest of the sign element  104 , thereby accentuating the alphanumeric characters  106 . The display panel assembly  100  further includes removable and adjustable partitioning elements  108  which partition the display area into two or more display areas, each capable of holding and displaying a unique sign element  104 . 
     FIG. 2 illustrates a perspective view of the display panel assembly  100  of FIG. 1 as it is being installed into a back-lighted sign assembly  150 . As shown in FIG. 2, the back-lighted sign assembly  150  includes a housing  160  for holding light sources  170  therein. Typically, these light sources are fluorescent light bulbs which are well-known in the art. The housing  160  has an open front face which has a perimeter of similar geometrical dimensions as the perimeter of the frame  102  of the display panel  100 , thereby allowing the display panel  100  to properly mate with the housing  160  such that the display panel  100  properly fits over the open cavity/face of the housing  160 . The display panel  100  may be secured, or attached, to the housing  160  by any means which is well-known in the art. The back-lighted sign assembly  150  further includes an electrical cord  180  having an electrical plug  190  for insertion into an electrical power outlet (not shown). 
     FIG. 3A illustrates one embodiment of the frame  102  of FIG. 1 as it appears after a certain number of manufacturing process steps have been performed. As shown in FIG. 3A, the frame  102  includes a substantially square, or rectangular, sheet of metal, which has been cut into a specified geometrical shape and pattern. The frame  102  includes a square, or rectangular, display window  204  which has been cut in the center or internal region of the metal sheeting  202 . In one embodiment, the metal sheeting  202  is an aluminum sheet having a specified thickness. However, the invention is not limited to any particular type of sheeting, metal or otherwise, and other types of sheeting or materials such as steel, plastics, etc., may be used in accordance with the invention. The sheeting  202  is cut such that flange elements  206  are formed along the left and right perimeters, and the bottom perimeter of the frame  102 . 
     As shown in FIG. 3A, the sheeting  202  has multiple partitioning apertures  208  cut adjacent to the left and right internal perimeter edge of the frame  102 . The functionality and purpose of these multiple partitioning apertures  208  are described in further detail below with respect to FIGS. 15-18. The sheeting  202  is also cut such that a rectangular corner section is cut away from the bottom left and right corners as shown by reference numerals  209 . The purpose of these cut-away corner sections  209  is to allow the flange elements  206  to be folded over, along the dashed lines shown so as to provide a flanged perimeter, or edge, of the frame  102 . The flanged edge reinforces the strength and support provided by the frame as the thickness along the flanged edge regions is twice that of the rest of the frame. As discussed in further detail below, the flanged edges  206  also provide a boundary for a transparent cover panel (not shown) which attaches to the front face of the frame  102 . 
     FIG. 3B illustrates a front view of the frame  102  after the flange elements  206  have been folded, as described above, in order to form the flanged edge/perimeter of the frame  102 . As can be seen from FIG. 3B, the flange perimeter portions  206  are of twice the thickness as the rest of the sheeting  202 , and therefore, are raised above the rest of the sheeting  202  by an amount equal to the thickness of the sheeting. Therefore, the raised flanged edges  206  surround ledge portions  207  which define the internal perimetric regions of the frame  102 . It is further appreciated that the flanged edges  206  of the frame  102  increase the strength and durability of the frame  102 . 
     FIG. 4 illustrates the frame  102  of FIG. 3B after strips of steel sheeting  210  have been attached to the interior ledges  207  of the frame  102 . The purpose of the steel sheet strips  210  is to provide a means for magnetically holding a transparent cover panel  250  as illustrated in FIG.  5 . The steel strips  210  may be attached to the ledge portions  207  by any means which is well-known in the art, such as, for example, double-sided adhesive tape, glue, etc. The transparent cover panel  250 , as illustrated in FIG. 5, includes a transparent sheet of plastic, or other suitable transparent material, which is cut in a shape and size which corresponds to the internal perimetric boundaries formed by the flanged portions  206  of the frame  102 , as illustrated in FIG.  4 . The transparent cover panel  250  also includes a perimetric border  254  which is either printed, painted or otherwise formed around the perimeter of the plastic sheet material  252 , thereby forming a colored border for the transparent cover panel  250 . Typically, the perimetric border  254  is printed such that it is of a matching color as the frame  102  so as to provide an appearance of continuity between the frame and the transparent cover panel. The perimetric border  254  may also be formed by means of applying tape to the perimeter of the plastic sheeting  252 . In one embodiment, the width of the perimetric border  254  corresponds to the width of the ledge portions  207  formed on the frame  102  as described above. 
     Referring to FIG. 6, a perspective view of the frame  102  and the transparent cover panel  250  as it is being attached to the frame  102  is illustrated. As shown in FIG. 6, the transparent cover panel  250  mates with the frame  102  such that the geometry of the outside perimeter of the transparent cover panel  250  substantially corresponds to the outside perimeter geometry of the ledge portions  207 , defined by the raised flanged edges  206  on a top edge of the metal sheeting  202 , of the frame  102 . 
     FIG. 7 illustrates a back-side view of the transparent cover panel in which magnetic elements are attached to the border areas  254  of the cover panel  250 . In one embodiment, the magnetic elements  256  are thin strips of flexible ferric magnetic material made from a rubber compound mixed with various chemicals having magnetic properties, such as ferrite and strongium, for example. Such types of flexible ferric magnets are well-known in the art and are manufactured by companies such as Magnet Source, Inc. of Denver, Colo., for example. In one embodiment, the magnetic elements  256  are attached to the border areas  254  by means of a double-sided adhesive tape, glue, or other attaching means which is well-known in the art. The magnetic elements  256  serve to hold a transparent cover panel flush against the ledge portions  207  of the frame  102 . FIG. 8 illustrates a top view of the transparent cover panel  250  after it has been magnetically attached to the frame  102 . 
     As illustrated in FIG. 8, after the transparent cover panel  250  has been magnetically attached to the frame  102 , the cover panel  250  is flush with the flanged borders  206  so as to provide an appearance that the cover panel  250  and the frame  102  are a single, unitary piece. 
     FIG. 9 illustrates a back-side view of the frame  102  in accordance with one embodiment of the invention. The frame  102  includes top and bottom retention members  302  and  304 , respectively, attached to the top boundary portion of the frame  102  and the bottom boundary portion of the frame  102 , respectively. The frame  102  further includes partitioning apertures  208  formed along the internal perimetric borders of the vertical ledge portions  207   b  and  207   d  of the frame  102 . Although the partitioning apertures  208  are illustrated as square or rectangular apertures, they are not limited to this configuration. Any desired geometric configuration may be used in accordance with the invention. 
     FIG. 10 illustrates a top view, taken along lines  10 — 10  of the frame  102  of FIG. 9 having the top retention member  302  attached thereto by a double-sided adhesive tape  306 . In one embodiment, the double-sided adhesive tape  306  is of a specified thickness so as to provide a specified spacing  308 , or channel  308 , between the top retention member  302  and the back-side of the frame  102 . 
     FIG. 11 shows a side-view of the frame assembly  102 , taken along lines  11 — 11  of FIG.  9 . As shown in FIG. 11, the frame assembly  102  has a top retention member  302  attached to the back side of a top ledge  207   a  by means of a double-sided adhesive tape  306 . The double-sided adhesive tape  306  is of a specified thickness so as to provide a channel  308  which serves to hold an edge of a slide or photo gel, as will be described in further detail below with respect to FIG. 12,  13  and  14 . FIG. 11 also illustrates the bottom retention member  304  attached to a bottom ledge portion  207   c  by means of double-sided adhesive tape  306 . As described above, the thickness of the double-sided adhesive tape  306  is of a specified value so as to provide a channel  308  for receiving therein an edge of a slide or photo gel (i.e., sign element). The ledge portion  207   d  and its corresponding flanged border  206  are also illustrated in FIG.  11 . Referring again to FIG. 9, the geometric relationship between the ledge portions  207   a,    207   b,    207   c  and  207   d  is clearly shown. In the side view of FIG. 11, the horizontal ledge elements  207   a  and  207   c  extend outwardly from the page and the vertical ledge portion  207   d  and its flanged border  206  are further back in the page and attach to the far ends of the horizontal ledge portions  207   a  and  207   c.    
     Referring to FIG. 12, the side view of the frame assembly  102 , as shown in FIG. 11, is illustrated with a photographic gel sign element  402  inserted at the back-side of the frame  102  such that the sign element  402  is held within channels  308  formed between the back-side of the sheeting  202  of the frame  102  and the top and bottom retention members  302  and  304 , respectively. 
     FIG. 13 illustrates a back-side view of the display panel assembly  100  after a single large sign element  402  has been inserted into the display panel  100 . The sign element  402 , otherwise known as a slide or a photo gel, is retained within channels  308  (FIG. 12) formed between the top and bottom retention members  302  and  304 , respectively, and the back-side of the sheeting  202  of the frame  102  of the display panel assembly  100 . The display panel assembly  100  also includes a first slide stop element  404  and a second slide stop element  406 . The purpose and function of the slide stop elements  404  and  406  is to prevent the sign element  402  from sliding either to the left or to the right as indicated by the double arrows  408 . The slide stop elements  404  and  406  are attached to the back-side of the left and right vertical ledge portions  207  of the frame  102 , respectively. In one embodiment, the slide stop element  406  is permanently attached to the back-side of the frame  202 , and is made from a rubber foam material which has been laminated with a plastic sheeting on its top surface. The purpose of the slide stop element  406  is to limit the motion of the sign element  402  from sliding past the slide stop element  406 , and therefore, any suitable material which is rigid and durable enough to prevent such sliding of the sign element  402  may be used in accordance with the invention. The slide stop element  406  may be permanently attached to the back-side of the frame  202  by means of a double-sided adhesive tape, glue, or any other means which is well-known in the art. 
     In one embodiment, the slide stop element  404 , on the other hand, is removably attached to the back-side of the frame  202 . When the slide stop element  404  is removed, the sign element  402  may be slid into the display panel assembly  100  within the channels  308  (FIG.  12 ). After the sign element  402  has been slid into place, the slide stop element  404  may then be attached to the back-side of the frame  202  so as to prevent the sign element  402  from sliding to the left as shown by directional arrows  408 . In one embodiment, the slide stop element  404  is made from a flexible ferric magnetic strip having a polycarbonate surface material attached thereto. The flexible ferric magnetic strip is commercially available from Magnet Source, Inc., of Denver, Colo., for example. The flexible, magnetic slide stop element  404  may be attached to the back-side of the frame  202  by means of a thin steel strip  308  which is permanently attached to the back-side of the frame  202 , as illustrated in FIG.  13 . The flexible, magnetized polycarbonate slide stop element  404  is magnetically attracted to the steel strip  409 , and therefore, magnetically adheres to the back-side of the frame  202 . 
     FIG. 14 illustrates a front view of the display panel assembly  100  after the sign element  402  is positioned within the display panel assembly  100 , as described above with reference to FIGS. 12-13. The transparent cover panel  250  is also shown covering the front surface of the sign element  402 . As also shown in FIG. 14, the flanged borders ledges  206  provide a means for supporting and aligning the transparent cover panel  250  such that it is properly held and oriented with respect to the frame  102  (FIG. 6) of the display panel assembly  100 . 
     FIG. 15 illustrates a back-side view of the display panel assembly  100  of the invention, wherein the display area  104  is partitioned into four separate display areas  104   a - 104   d  by partitioning elements  502 . The display panel assembly  100  includes the top and bottom retention members  302  and  304 , respectively, slide stop elements  404  and  406 , and partitioning apertures  208  which are stamped, or die-cut, into the sheet  202  of the frame  102  (FIG.  3 A), as described above. 
     Referring to FIG. 16, a cross-sectional side view when looking toward a direction corresponding to line  16 — 16  of FIG. 15, is illustrated. Two partitioning elements  502  support and hold a sign element  104   c  within channels  504  formed within the partition elements  502  as illustrated in FIG.  16 . Each of the partitioning elements  502  are attached to the frame assembly  102  (FIG. 9) by means of magnet elements  506  which are attached to each end of each partitioning element  502 . The magnet elements  506  fit into the partitioning apertures  208 , as described in further detail below with respect to FIG.  18 . Slide channels  504  are on each side of the partitioning element  502  and run longitudinally along the length of the partitioning elements  502 . Therefore, each partitioning element  502  can serve to provide a slide channel  504  for two sign elements  104  on either side of the partitioning element  502 . 
     Referring to FIG. 17, each slide channel  504  runs longitudinally and parallel to the length of the partitioning element  502 . The partitioning element  502  further includes lateral indentations or grooves  508  near each end of the partitioning element  502 . The indentations  508  define a locking member  507  at each end of the partitioning element  502 . Attached to the bottom surface of each locking member  507  is a magnet element  506 . Referring once again to FIG. 16, it is seen that the magnet element  506  is lodged into the locking member  507  by means of a beveled channel in locking member  507  which receives a bevel shaped magnet element  506 , thereby securely holding the magnet element  506  within the locking member  507 . In one embodiment, to further increase the adhesion between the magnet element  506  and the locking member  507 , the magnet element  506  is glued into the beveled channel of the locking member  507 , using any suitable glue which is well-known in the art. 
     Referring to FIG. 18, a close-up view of how the locking element  507  of the partitioning element  502  mates with the partitioning aperture  208  of the frame sheeting  202 , is illustrated. As shown in FIG. 18, the locking member  507  locks into a partitioning aperture  208 . It is desirable for the dimensions of the locking member  507  to correspond to the dimensions of the partitioning aperture  208  so as to be “form-fitted” therein such that each time the partitioning element  502  is inserted into a particular partitioning aperture  208 , the orientation and alignment of the partitioning element  502  will remain essentially constant. In other words, the partitioning element  502 , after it has been placed in a partitioning aperture  208  should not be able to “jiggle” or shift its position, thereby providing uniform positioning of the partitioning elements  502  with respect to each partitioning aperture  208 . As the locking member  507  fits into partitioning aperture  208 , the lateral indentation  508  formed on the bottom side of the partitioning element  502  form fits with the portion of the frame  102  formed between the aperture  208  and the internal perimeter of the frame  102  (FIGS.  3 A- 3 B). After the partitioning element  502  has been locked into position, as described above, it is held in its respective position by means of magnet element  506  which is magnetically attracted to the strip of steel sheeting  210  which is attached to the front surface of the frame  102 , as described above with reference to FIG.  4 . The slide stop element  404  prevents a slide or photo gel from sliding out of the slide channels  504  after the partitioning element  502  has been locked into place as described above. 
     FIG. 19 illustrates one embodiment of a detachable slide stop element  404  in accordance with the invention. The removable slide stop  404  may be made from a flexible, magnetic polycarbonate material, or other suitable material that may be magnetized, or it may be a more rigid element such as a strip of magnetized metal, rubber, plastic, etc. The invention is not limited to the type of material which may be used to provide the slide stop  404 . As illustrated in FIG. 19, the slide stop  404  includes multiple retention flaps  405  which are spaced and configured so as to extend between the spacings of adjacent partitioning apertures  208 . In this way, the slide stop  404  not only prevents a slide or photo gel  104  from sliding out of the channels (not shown) of the partitioning elements  502 , but also provides additional support and stability by holding and securing the end of the slide  104  underneath the retention flaps  405 . 
     FIG. 20 illustrates a cross-sectional view, taken along lines  20 — 20  of FIG. 19, of the slide stop  404  with the retention flap  405  engaged with one end of a slide  104  so as to provide support and stability to the end of the slide  104 . The slide stop  404  is removably attached to the back side of the metal sheet  202  of the frame  102  by a thin strip of steel sheeting  408 , or other suitable type of sheeting having magnetic properties capable of attracting the magnetized slide stop  404 . 
     FIG. 21 illustrates one embodiment of a sign element  600 , otherwise known as a slide  600 , which may be used in accordance with the present invention. The slide  600  includes a front piece  602  having alphanumeric characters  604  stamped, printed, or otherwise illustrated on the front piece  602 . The front piece  602  also has one or more windows  606  cut or stamped in the front piece  602 . As described in further detail below, these windows  606  allow numerical price values to be illustrated therethrough. The slide  600  also includes a back piece  608 , which is typically made of a plastic material of opaque coloring, designed to illuminate a white light when radiated from behind by a light source  170  (FIG.  2 ). The back piece  608  also has one or more pockets  610  having windows  612  therein for holding and displaying numerical inserts, or other types of symbols. The pockets  610  are typically made from a clear plastic material which is adhesively attached to the back piece  608 . The windows  612  are stamped, or die-cut into a plastic sheet material which forms the outer surface of the pockets  610 . 
     Referring to FIG. 22, a first process step of forming the pocket  610  is illustrated. One of the first steps is to apply strips of double-sided adhesive tape  614  laterally across the width of the back slide piece  608 . 
     FIG. 23 illustrates a rectangular piece of die-cut plastic sheet material  616  having windows  612  cut therein which forms the front surface of the pockets  610 . 
     FIG. 24 illustrates the pockets  610  after the die-cut sheet material  616  has been attached to the back piece  608  by means of the double-sided adhesive strips  614  which are illustrated by dashed lines indicating that they are under the plastic sheet material  616 . 
     FIG. 25 shows a top view, taken along lines  25 — 25  of FIG. 24 which illustrates the pockets  610  formed between the back piece  608  and the plastic sheet material  616  which is attached to the back piece  608  by means of double-sided adhesive strips  614 . The thickness of the adhesive strips  614  is chosen so as to provide a specified spacing between the sheeting material  616  and the back piece  608 , thereby providing a pocket of the specified dimensions. It is also appreciated that the spacing between adjacent strips of double-sided adhesive tape  614  defines the width of each pocket  610 . 
     FIG. 26 illustrates numerical inserts  618  which may be inserted into the pocket  610 , and removed from the pockets  610  as desired. Therefore, the pockets  610  allow easy interchangeability of characters such as numerical inserts  618  if, for example, a price change of a specific menu item is desired. 
     FIG. 27 illustrates the slide  600  after the front piece  602  has been attached to the back piece  608 . Typically, the characters  604  and numerals are clear so as to show through to the opaque coloring of the back piece  608 . However, any color combination of the characters and the rest of the slide background may be implemented. When illuminated from behind, the characters are typically accentuated because of their contrasting color with the rest of the background of the slide  600 , thereby providing an attractive and accentuated advertisement. 
     In one embodiment, the windows  606  which are cut in the front piece  602  are cut so as to be slightly smaller than the pocket windows  612  cut in the plastic sheeting  616 . The reason for this is to eliminate a “halo” effect caused by light diffusing through the clear plastic sheeting  616  and radiating outwardly from the internal, peripheral edges which define the pocket windows  612 . 
     This phenomenon is illustrated in FIG.  28 . When the sign element  600  is illuminated from behind, light diffuses through the back piece  608  (FIG. 25) and through the clear plastic sheeting  616 . Some of the diffused light radiates outwardly from the internal, peripheral edges of the windows  612  cut in the plastic sheeting  616 . This may cause a “halo” or ring of light to surround an insert  618  (FIG. 26) displayed through the window  606  of the front piece  602 . Such a halo obscures the contrast between the numerical insert  618  and the rest of the background of the sign element  600  and, additionally, detrimentally affects the overall aesthetic appearance of the sign element  600 . Therefore, it is extremely desirable to eliminate this halo effect. 
     As mentioned above, to reduce or eliminate the “halo” effect, in one embodiment, the front piece  602  is manufactured such that the windows  606  in the front piece  602  are cut slightly smaller than the pocket windows  612  which are cut in the plastic sheeting  616  which forms the pockets  610 . As one “rule of thumb,” the windows  606  in the front piece  602  should be cut such that after the front piece  602  is properly aligned with the back piece  608 , each internal peripheral edge of the front piece window  606  should be “inside” a corresponding internal peripheral edge of a pocket window  612  by a distance of three times the thickness of the plastic sheeting  616 . Therefore, if the plastic sheeting  616  is 5 mils ({fraction (5/1000)} inches) thick, each internal peripheral edge of the front piece window  606  should be 15 mils inside the corresponding internal peripheral edge of the pocket window  612 . 
     Referring to FIG. 29, the geometric relationship between the front piece window  606  and the pocket window  612  is illustrated. The internal peripheral edges of the front piece window  606  is illustrated by lines  650  and the internal peripheral edges of the pocket window  612  is illustrated by the dashed lines  652 . The dashed lines  652  indicate that the larger pocket window  612  is located behind the front piece window  606  and that the internal peripheral edges  652  of the pocket window  612  would normally not be visible due to the front piece  602 . As shown in FIG. 29, the internal peripheral edges  650  of the front piece window  606  are “inside” the internal peripheral edges  652  of the pocket window  612  by distances specified by A—A, B—B, C—C and D—D. Taking our “rule of thumb” described above, if the thickness of the plastic sheeting  616  (FIG. 23) in which the pocket window  612  is cut, is 5 mils, the distances A—A, B—B, C—C and D—D should be approximately 15 mils. In this way, any light which diffuses outwardly from the internal peripheral edges  652  of the pocket window  612  is blocked or obscured by internal, peripheral areas of the front piece window  606 , thereby eliminating the “halo” effect. 
     The above described “rule of thumb” significantly reduces, or eliminates, the “halo” effect. However, the invention is not limited to the above-described size ratios between the front piece windows  606  and the pocket windows  612 . For example, the front piece windows may be cut larger or smaller as that described above, depending on different types of materials that may be used which could impact the “halo” effect, the intensity of the back-light, the relative, overall size of the front piece windows and the pocket windows, the thickness of the plastic sheeting  616  (FIG.  23 ), etc. The general inventive aspect of manufacturing is that the front piece window  606  should be cut smaller than a corresponding pocket window  612  such that the internal peripheral edges  652  of the pocket window  612  is obscured from view so as to substantially, or completely, eliminate the halo effect. 
     One advantage of the sign element  600 , or slide  600 , as described above is that, after the correct dimensions are determined, the front piece  602  is easily manufactured by die-cutting and printing relatively inexpensive plastic sheet material. Therefore, if a menu item is desired to be changed, or a new menu item is desired to be advertised, it is a relatively simple matter to cut and print a new front piece  602  which illustrates the desired new menu item or product, or message. In contrast, the back piece  608  along with its corresponding pockets  610  is more difficult to manufacture, and thus, more costly. Therefore, it is desirable to be able to reuse the back piece  608  when a new menu item, for example, is to be displayed. 
     In accordance with the invention, in order to change the slide assembly  600  to illustrate a new menu item, product, or message, only the front piece  602 , which is relatively inexpensive to manufacture, need be replaced. The pricing is easily modified as described above with reference to FIG.  26 . Therefore, the only materials that need be replaced is the front piece  602 , and possibly the numerical inserts  618  (FIG. 26) in order to completely change a particular sign element, or slide  600 . This not only results in a savings of over 50% of the cost in terms of materials but also a significant amount of manufacturing time and cost expended to produce the back piece  608  and the corresponding pockets  610  is saved for each slide  600 . 
     In one embodiment, the front piece  602  is attached to the back piece  608  by means of a double-sided transfer tape which is well-known in the art. The double-sided transfer tape has one side which has a permanent adhesive and another side that has a temporary adhesive. The permanent adhesive side is attached to the back piece  608  while the temporary adhesive side is facing the front piece  602  and sticks to the front piece  602  when the front piece  602  is attached to the back piece  608 . However, any method of removably attaching the front piece  602  to the back piece  608 , such as a weak glue, “Velcro,” etc., may be used in accordance with the invention. 
     The foregoing describes an adjustable display panel assembly in which a display window may be easily and adjustably partitioned into various desired configurations so as to accommodate a desired number of sign elements of varying sizes and shapes. Therefore, the display panel assembly of the invention may be easily and repeatedly modified to provide different configurations of displays such that new messages, menu items, images, etc. of varying sizes and dimensions may be implemented in the display panel assembly, without changing the overall size of the display panel. Additionally, the invention provides an improved sign element to be used in the adjustable display panel, wherein a front piece is removably attached to a back piece, such that when an old menu item, for example, is to be replaced with a new one, only the front piece of the sign element need be replaced. 
     The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.