Abstract:
There is provided a light emitting assembly for a backlighted sign. The assembly may include first and second light emitting units configured to emit light in corresponding first and second directions into edges of first and second adjacent light guide plates. The assembly may also include a third light emitting unit configured to emit light in a direction substantially transverse to the first and second directions into a backlightable sign panel. Light emitting units are slidably insertable and slidably removable.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to illuminated signs such as backlighted signs having an information or visual content bearing front panel with translucent and/or transparent portions through which backlighting may be perceived. The present invention relates to configurations and layouts of backlighting elements for such signs. 
     2. Description of the Related Art 
     Generally a sign or advertisement board may be formed by printing characters and/or images or attaching printed material on the surface of a metallic plate or a synthetic resin plate. However, such advertisement boards have low visual recognition in daytime and worse visual recognition at night and in snowy, rainy and foggy weather conditions, such that an observer, such as a vehicle driver or passenger, cannot easily recognize the sign&#39;s information content. 
     With reference to  FIGS. 1A and 1B , a conventional backlighted illuminated advertisement board  40  may have one or more light guide plates  10  and light emitting diode (LED) units  20  installed behind a sign panel  50 . LED units  20  are affixed to direct light into the edge of an adjacent light guide plate  10  which redirects the light into its surface and sign panel  50  so that the light may be transmitted through transparent or translucent portions of sign panel  50  and observed by an observer. In this way, visibility and recognition of information content of board  40  is possible in bad weather and at night. 
     However, such conventional boards suffer from uneven illumination in which light does not reach central portions, especially with larger advertisement boards. For example, area  55  of sign panel  50 , not positioned directly above a light guide plate, may not receive the same amount of backlighting as the remainder of sign panel  50 . Observers are unable to recognize the visual content of such portions of conventional advertisement boards. Such conventional signs may also have a visible dark seam corresponding to the location of adjacent light guide plates. Moreover, the conventional board is not constructed for ease of replacement of LED units. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a light emitting structure for an illuminated sign which overcomes the problems encountered in the conventional art. 
     It is another object of the present invention to provide a light emitting structure for a backlighted sign which is capable of uniformly emitting light to all portions of a sign panel by providing interior light emitting units capable of emitting light in a T-shape, upwardly into a center portion and laterally into one or more light guide plates, so that it is possible to more fully illuminate the information on the sign and render it recognizable to observers. 
     In addition, light emitting units according to the present invention may be slidably insertable and slidably removable between a frame and a light guide plate or between light guide plates, so that light emitting units may be easily exchanged when damaged or needing maintenance. 
     In accordance with an embodiment of the invention, there is provided a light emitting assembly for a backlighted sign. The assembly includes first and second light emitting units configured to emit light in corresponding first and second directions into edges of first and second adjacent light guide plates and a third light emitting unit configured to emit light in a direction substantially transverse to the first and second directions and into a backlightable sign panel. 
     In some embodiments, the light emitting assembly may include the first adjacent light guide plate and the second adjacent light guide plate. In some embodiments, at least one of the first, second and third light emitting units comprises light emitting diodes. In some embodiments, at least one of the first, second and third light emitting units is slidably insertable into the assembly. In some embodiments, the light emitting assembly includes transparent molding disposed on at least one of the light emitting units, the molding arranged to prevent water ingress upon electrical components of the light emitting unit and being composed of transparent epoxy or a silicone-based compound. In some embodiments, a light emitting unit comprises a heat sink and the transparent molding is disposed therein. In some embodiments, the heat sink has a U-shaped profile. 
     In some embodiments, the light emitting assembly includes a heat sink with a substantially U-shaped profile. The first and second light emitting units are disposed on opposite sides of the heat sink and, for any given cross-section, are oriented to direct light in opposite directions. The third light emitting unit is disposed within the heat sink and is oriented to direct light toward the opening of the heat sink. In some embodiments, the light emitting assembly further includes a transparent cover disposed along the sides and over the opening of the heat sink with a substantially U-shaped profile, the transparent cover being configured to transmit light emitted from the third light emitting unit. 
     According to yet other embodiments, there is provided a backlighted sign having the light emitting assembly discussed above, first and second adjacent light guide plates, and a backlightable visual content panel. Light emitting units have installed positions in which they are disposed between the first and second adjacent light guide plates and behind the backlightable visual content panel and are slidably insertable and slidably removable from the installed position. The backlighted sign may further comprise a frame and one or more edge light emitting assemblies configured and arranged to emit light into at least one edge of the first and/or second adjacent light guide plates. 
     The above and other aspects and embodiments are described below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. In the drawings, like reference numbers indicate identical or functionally similar elements. 
         FIGS. 1A and 1B  illustrate a perspective view and detail insets and a sectional view, respectively, of a prior art illuminated sign apparatus. 
         FIG. 2  illustrates a perspective view and detail insets of an illuminated sign apparatus in accordance with embodiments of the invention. 
         FIG. 3  illustrates a detailed sectional view of the illuminated sign apparatus of  FIG. 2  in accordance with embodiments of the invention. 
         FIG. 4  illustrates an exploded perspective view of a detail inset of the illuminated sign apparatus of  FIG. 2  in accordance with embodiments of the invention. 
         FIGS. 5 and 6  illustrate alternate embodiments of sign apparatuses in accordance with embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 2 , according to an embodiment of the present invention, a structure for a backlighted sign  99  is provided. The structure may include a frame  100 , light emitting unit insertion areas  700  with light emitting units  735  inserted therethrough, light guide plates  300  and visual content sheet  500  disposed on surfaces of light guide plates  300 . Light guide plates  300  may be configured to direct light from an edge thereof to a surface thereof. 
     In one embodiment, frame  100  is made of a metallic material or a reinforced plastic material for preventing the frame from being damaged by means of an external impact. The size of frame  100  is generally dependent on the size of the sign to be manufactured. 
     One or more light guide plates  300  are disposed in the interior of the frame  100  and are configured to direct light incident on one or more edges thereof from light emitting units  735  to a surface of light guide plate  300 , so that the visibility of the information of visual content sheet  500  is enhanced. The number of light guide plates  300  for a particular backlighted sign is determinable by the size of visual content sheet  500 , the brightness of light emitting units  735 , the efficiency of light guide plates  300  and the desired brightness of board  99 . Space is maintained between adjacent light guide plates  300  and between a light guide plate  300  and frame  100  so that light emitting units  735  may be slidably inserted and slidably removed through light emitting unit insertion areas  700 . In  FIG. 2 , the right-edge light emitting unit  735  is slidable on axis X and is shown partially inserted. 
     Visual content sheet  500  is disposed on the surfaces of light guide plates  300 . Visual content sheet  500  may be an advertisement sheet. Visual content sheet  500  may include variously transparent and/or translucent portions in one or more colors, such that the portions form images and characters having visual information content. Visual content sheet  500  is preferably made of a transparent synthetic resin. 
     Light emitting units  735  may be positioned along a sign edge as shown in detail  710  and/or in interior areas as shown in detail  730 . Light emitting units  735  comprise one or more light sources such as light emitting diodes (LEDs) and may also include one or more heat sinks as further discussed below. As shown in detail  710 , at an edge portion of the backlighted sign, e.g., adjacent to frame  100 , a light emitting unit  735  may be arranged to direct light into a light guide plate  300  to redirect light to a surface of the light guide plate  300  for backlighting visual content sheet  500 . As further illustrated in detail  730 , in an interior portion of the backlighted sign, e.g., between neighboring light guide plates  300 , interior light emitting units  735  are configured to emit light both into adjacent light guide plates  300  and into visual content sheet  500 . 
     With reference to  FIG. 3 , light sources  735  may comprise a substrate  735 - 1  and one or more light emitters  735 - 3 , molded by a transparent epoxy  735 - 5  or a silicon material of a certain length in order to prevent electric leakage resulting from moisture ingress, e.g., from rain water or condensation. Light emitters  735 - 3  may comprise one or more LEDs. Light emitters  735 - 3 , substrate  735 - 1  and epoxy  735 - 5  may be disposed in a heat radiating channel  735 - 7 . Heat radiating channel  735 - 7  may comprise one or more fins for dissipating heat and may be constructed of aluminum or other heat conductive materials. Heat radiating channel  735 - 7  may have a U-shaped profile. 
     As illustrated in detail  730  in  FIGS. 3 and 4 , interior light emitting insertion areas  700  may include U-shaped heat radiating plate  731 , light sources  735  and transparent cover  737 . Interior light emitting units  735  are disposed to emit light into edges of adjacent light guide plates  300  and in a generally transverse direction into visual content sheet  500 . Transparent cover  737  may cover the open portion of heat radiating plate  731  and be positioned at a connection portion of adjoining light guide plates  300 . 
     Since they are slidably insertable and slidably removable between frame  100  and light guide plate  300  or between light guide plates  300 , ease of assembly is facilitated and light emitting units  735  can also be easily exchanged when damaged or requiring maintenance. 
     Side light emitting units  735  as illustrated in detail  710  may emit light at a sign edge portion and, as shown in detail  730 , interior light emitting unit  735  may emit light from an interior area of the sign. Thus, in accordance with embodiments of the invention, seamless and/or uniform backlighting is provided to visual content sheet  500  so that the informational content is perceivable under various environmental conditions. 
     With reference to  FIG. 5 , a backlighted sign  98  is provided. Backlighted sign  98  has a similar constitution to backlighted sign  99  with frame  100 , one or more light guide plates  300 , one or more slidably insertable light emitting units  735 , one or more light emitting unit insertion areas  700  and visual content sheet  500 . Backlighted sign  98 , however, is triangle-shaped. With reference to  FIG. 6 , a backlighted sign  97  is provided. Backlighted sign  97  has a similar constitution to backlighted signs  98  and  99  with frame  100 , one or more light guide plates  300 , one or more slidably insertable light emitting units  735 , one or more light emitting unit insertion areas  700  and visual content sheet  500 . Backlighted sign  97 , however, is octagon-shaped. Backlighted signs  97  and  98  may comprise multiple light emitting units  735  disposed along one or more edges thereof. Optionally, backlighted signs  97  and  98  may have light emitting units  735  disposed in an interior region (not shown), in a manner similar to that illustrated in  FIG. 3 . 
     Thus, according to embodiments of the invention, it is possible to uniformly and/or seamlessly backlight an arbitrarily large visual content sheet  500  so information thereon may be easily recognized. 
     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. For example, the present invention is not limited to signs having rectangular, triangular or octagonal shapes. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments.