Abstract:
A scalable tiled display assembly that includes an array of independently addressed active-matrix organic light-emitting diode (OLED) display tiles cabled to a central control module. Each display tile includes a frame, a driver sub-module, and a flat ribbon cable for connecting the driver sub-module to the display tile. Furthermore, column and row drivers are integrated within each display tile for improved performance and minimal external connections. The invention further includes a method of forming a scalable tiled display system that includes the steps of assembling a plurality of display tile assemblies, determining the viewable area of the display, assembling an array of display tile assemblies according to the desired viewable area, and activating the scalable tiled display system.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a modular large-screen organic light-emitting diode (OLED) display. In particular, the invention relates to a scalable tiled display assembly for forming a large-area flat-panel display using modular display tiles.  
       BACKGROUND OF THE INVENTION  
       [0002]     OLED technology incorporates organic luminescent materials that produce intense light of a variety of colors when sandwiched between electrodes and subjected to a DC electric current. These OLED structures can be combined into the picture elements, or pixels, that comprise a display. OLEDs are also useful in a variety of applications as discrete light-emitting devices or as the active element of light-emitting arrays or displays, such as flat-panel displays in watches, telephones, laptop computers, pagers, cellular phones, calculators, and the like. To date, the use of light-emitting arrays or displays has been largely limited to small-screen applications, such as those mentioned above.  
         [0003]     Demands for large-screen display applications that possess higher quality and higher light output has led the industry to turn to alternative display technologies that may replace older light-emitting diode (LED) and liquid crystal displays (LCDs). For example, LCDs fail to provide the bright, high light output, larger viewing angles and speed requirements that the large-screen display market demands. By contrast, OLED technology promises bright, vivid colors in high resolution, high speed reaction and at wider viewing angles. However, the use of OLED technology in large-screen display applications, such as outdoor or indoor stadium displays, large marketing advertisement displays, and mass-public informational displays, is only beginning to emerge. Consequently, the market is now demanding larger displays that have the flexibility to customize display sizes.  
         [0004]     Modular or tiled displays are made from smaller modules or displays that are then combined into larger displays. These tiled displays are manufactured as a complete unit that can be further combined with other tiles to create displays of any size and shape. Two barriers to implementing the tiled approach have been: 1) eliminating the visibility of the seams between tiles; and 2) providing electrical access to the pixels. No practical tiled display system has yet been developed (video walls formed by abutting conventional cathode ray tube (CRT) displays are not considered tiled because of their wide separations between adjacent displays). Accordingly, there is a need for a scalable modular OLED display that is cost-effective, seamless, and is easy to assemble electrically and mechanically.  
         [0005]     An examplary tiled display is described in U.S. Pat. No. 5,644,327, entitled “Tessellated Electroluminescent Display having a Multilayer Ceramic Substrate.” The &#39;327 patent describes an electroluminescent display and a combination field emissive and electroluminescent display which are formed as tiles that may be joined together to provide a large-area display device. The exemplary tiles are formed using low-temperature cofired ceramic and metal structures consisting of multiple layers of ceramic circuit-board material laminated to a metal core. Driving circuitry for the displays is mounted on the back of the structures and vias are passed through the structure from the back to the front in order to make connection with the pixel electrodes on the front of the display device.  
         [0006]     Although the tiled display described in the &#39;327 patent provides a means for interconnecting tiles to create a large display system, the &#39;327 patent fails to provide a scalable modular OLED display that is easy to assemble and is low cost.  
         [0007]     It is therefore an object of the invention to provide a scalable modular OLED display that is cost-effective, seamless, and is easy to assemble electrically and mechanically.  
         [0008]     It is another object of this invention to provide a cost-effective way of forming an arbitrarily large flat-panel display.  
         [0009]     It is yet another object of this invention to provide an OLED display module that can be used as a component for easily scaling a flat-panel display to any size.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     The present invention is a scalable tiled display assembly for forming a large-area flat-panel display by using display tiles that are easily assembled in a modular fashion. The scalable tiled display assembly of the present invention is formed of an array of independently addressed display tiles that are assembled in a modular fashion to achieve a seamless large-area flat-panel display of any desired size. Additionally, column and row drivers are integrated within each display tile for improved performance and minimal external connections. Furthermore, the scalable large-area flat-panel display of the present invention is thin, light weight, and low cost. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1A  illustrates a front view of a display tile that has integrated column and row drivers in accordance with the invention;  
         [0012]      FIG. 1B  illustrates an expanded view of a column driver region of the display tile of the present invention;  
         [0013]      FIG. 2  illustrates a perspective view of a display tile assembly in accordance with the invention;  
         [0014]      FIG. 3  illustrates a front view of a tiled display that is scalable to any size by assembling an array of display tiles in accordance with the invention;  
         [0015]      FIG. 3B  is an end view of the tiled display of  FIG. 3A ;  
         [0016]      FIG. 4  illustrates a perspective view of a scalable tiled display system that is scalable to any size by assembling an array of display tile assemblies in accordance with the invention; and  
         [0017]      FIG. 5  illustrates a flow diagram of a method of forming a scalable tiled display system in accordance with the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]      FIG. 1A  illustrates a front view of a display tile  100  that has integrated column and row drivers. Display tile  100  is suitable for use in a modular flat-panel display in accordance with the invention. Display tile  100  is a thin (100-150 μm) flexible active matrix OLED display panel that is, for example, 10 to 12 inches square. Display tile  100  includes an active matrix region  110 , which includes electronic circuitry for an array of light-emitting devices, such as OLEDs. Display tile  100  is bounded by a first edge  112 , a second edge  114 , a third edge  116 , and a fourth edge  118 . Display tile  100  further includes a column driver region  120  along first edge  112  and a row driver region  122  along second edge  114 . Column driver region  120  includes integrated column drivers for receiving the display data. Row driver region  122  includes integrated row drivers for receiving the pulsed row signals, as is well known. The design of display tile  100  includes the integrated drivers, which allow for high performance drivers with regard to speed and current capability, as display tile  100  uses cadmium selenide (CdSe) for forming the electronic elements instead of the lower performance amorphous silicon used with LCDs. The integrated row and column drivers of column driver region  120  and row driver region  122  are formed with the same manufacturing process as active matrix region  110 .  
         [0019]      FIG. 1B  illustrates an expanded view of a column driver region  120  that further includes an exemplary arrangement of electrodes  124  along the outer edge of display tile  100  that allow for electrical connections to an associated exemplary arrangement of drivers  126  for driving active matrix region  110 . In like manner, row driver region  122  includes an arrangement of electrodes  124  and an arrangement of drivers  126 . There is one driver  126  associated with each row and column within active matrix region  110 . There is one electrode  124  associated with each driver  126 .  
         [0020]     With reference to  FIGS. 1A and 1B , the placement of column driver region  120  and row driver region  122  (with electrodes  124  and drivers  126 ) is not limited to two separate edges, respectively. Column driver region  120  and row driver region  122  may both be formed on a single edge only, for example. The width of column driver region  120  and row driver region  122  is any suitable dimension for providing a layout of electrodes  124  and drivers  126  that is practical for making connections to an external cable, for example.  
         [0021]      FIG. 2  illustrates a perspective view of a display tile assembly  200  in accordance with the invention. Display tile assembly  200  includes display tile  100  mounted atop a display tile frame  210 . Display tile frame  210  further includes multiple cable clearance slots  212  for feeding a cable (not shown) from a driver sub-module  214  to column driver region  120  and row driver region  122  of display tile  100 , for example, a cable clearance slot  212 a for feeding a cable (not shown) from driver sub-module  214  to column driver region  120  and a cable clearance slot  212 b for feeding a cable (not shown) from driver sub-module  214  to row driver region  122 . The individual conductors of the cables, such as standard flat ribbon cables, from driver sub-module  214  are electrically connected to electrodes  124  of column driver region  120  and row driver region  122  via soldering or clamping.  
         [0022]     Driver sub-module  214  provides a second set of active drivers as a signal distribution mechanism for addressing drivers  126  of column driver region  120  and row driver region  122  and, thus, provides the drive data and picture information to display tile  100 . Driver sub-module  214  also provides power and timing signals to its associated tile. Driver sub-module  214  is, for example, a standard printed circuit board with active driver devices. Driver sub-module  214  is located behind display tile  100  and is sized suitably small enough to fit within display tile frame  210 . Display tile frame  210  is formed of any suitable lightweight and rigid material, such as molded plastic or aluminum. Display tile frame  210  forms a physical cage of support for display tile  100  at the edges of display tile  100 .  
         [0023]      FIG. 3A  illustrates a front view of a tiled display  300  that is scalable to any size by assembling an array of display tiles  100  in accordance with the invention. For example,  FIG. 3A  shows a 2×2 arrangement of a display tile  100   a,  a display tile  100   b,  a display tile  100   c,  and a display tile  100   d.  Tiled display  300  is not limited to the 2×2 arrangement shown in  FIG. 3A . Tiled display  300  is scalable to any arbitrary number of display tiles  100  to form a large-area tiled display  300  of any desired dimension.  
         [0024]     In the example of  FIG. 3A , fourth edge  118   b  of display tile  100   b  overlaps row driver region  122   a  (not visible) at second edge  114   a  of display tile  100   a,  third edge  116   c  of display tile  100   c  overlaps column driver region  120   a  (not visible) at first edge  112   a  of display tile  100   a,  third edge  116   d  of display tile  100   d  overlaps column driver region  120   b  (not visible) at first edge  112   b  of display tile  100   b,  and fourth edge  118   d  of display tile  100   d  overlaps row driver region  122   c  (not visible) at second edge  114   c  of display tile  100   c.  As a result, only active matrix region  110  of each display tile  100  is visible and, thus, tiled display  300  appears as seamless to the viewer thereof.  
         [0025]      FIG. 3B  is an end view of tiled display  300  of  FIG. 3A . In this view, the overlap of fourth edge  118   b  of display tile  100   b  upon row driver region  122   a  (not visible) at second edge  114   a  of display tile  100   a  is evident. Additionally,  FIG. 3B  shows that tiled display  300  includes a plurality of ribbon cables  310 . For example, a ribbon cable  310   a  sandwiched between display tile  100   a  and display tile  100   b  that is mechanically and electrically connected to electrodes  124  (not visible) of display tile  100   a.  Likewise, a ribbon cable  310   b  is mechanically and electrically connected to electrodes  124  (not visible) of display tile  100   b.  Each display tile  100  is independently powered and addressed via its own ribbon cable  310 . The total thickness of tiled display  300  at the overlap area is in the range of 6 to 10 mils. Alternatively, the ribbon cable electrodes (i.e., electrodes  124 ) may be replaced by electrodes formed on the edge on the backside of each display tile  100 . This would allow ribbon cable  310  to come off the back of display tile  100 , rather than be sandwiched between one display tile  100  and the next, thereby reducing the total overlap thickness.  
         [0026]      FIG. 4  illustrates a perspective view of a scalable tiled display system  400  that is scalable to any size by assembling an array of display tile assemblies  200  in accordance with the invention. For example,  FIG. 4  shows a 2×2 arrangement of a display tile assembly  200   a,  a display tile assembly  200   b,  a display tile assembly  200   c,  and a display tile assembly  200   d.  Scalable tiled display system  400  further includes a central control module  410  that is electrically connected to the array of display tile assemblies  200  via a cable  412 . More specifically, cable  412  is representative of a bundle of cables that connect central control module  410  to/from all driver sub-modules  214  that are present within scalable tiled display system  400 . On one end each cable within the bundle represented by cable  412  is electrically connected to its associated driver sub-module  214  via soldering or a standard multi-pin cable connector. Similarly, the opposite end is electrically connected to the electronics of central control module  410  via a standard multi-pin cable connector. Central control module  410  serves as the central image processor. Central control module  410  controls the scanning and illumination of the pixels on each display tile  100 .  
         [0027]     A second set of ribbon cables  310  (not shown) connects each driver sub-module  214  to electrodes  124  of its respective display tile  100 . Cable  412  also handles the power distribution and timing signals to all driver sub-modules  214  and display tiles  100 . The structure of scalable tiled display system  400  forms physical cages of support (i.e., display tile frames  210 ) with the face of the individual display tiles  100  arranged seamlessly along a common visible plane, whereby all substructures and cables are hidden from view.  
         [0028]     In operation, central control module  410  addresses each driver sub-module  214  via cable  412  with their respective picture information, i.e., drive data, brightness, and picture information. Central control module  410  serves at the image processor that provides image data that is specific to each display tile  100 , based upon the physical location of each given display tile  100  within the overall scalable tiled display system  400  and, thus, each display tile  100  is independently addressed. Central control module  410  controls the scanning and illumination of the pixels on each display tile  100 . Each driver sub-module  214  then distributes the signals via ribbon cables  310  to its respective display tile,  100  and, thus, addresses its respective column driver region  120  and row driver region  122 . As is well known, row driver elements are excitable one at a time, while column drivers receive the picture data and then store it in local memory, which is then energized by the row gating signals.  
         [0029]      FIG. 5  illustrates a flow diagram of a method  500  of forming a scalable tiled display system  400  in accordance with the invention.  
         [0030]     At step  510 , a plurality of display tile assemblies  200  are formed by a flat-panel display manufacturer for use within a scalable tiled display system  400 . At step  512 , the flat-panel display manufacturer (or display system customer) determines the size of the viewable area of the display scalable tiled display system  400  and, thus, determines the required configuration of the array of display tile assemblies  200 . At step  514 , the flat-panel display manufacturer assembles the plurality of display tile assemblies  200  edge-to-edge, according to the configuration determined at step  512 . The flat-panel display manufacturer also connects all ribbon cables  310  between all driver sub-modules  214  and their respective display tiles  100  and connects cable  412  between all driver sub-modules  214  and central control module  410 , accordingly. At step  516 , the user activates scalable tiled display system  400  via central control module  410 , which supplies image data that is specific to each display tile  100 , based upon the physical location of each given display tile  100  within the overall scalable tiled display system  400  and, thus, each display tile  100  is independently addressed. Method  500  ends.  
         [0031]     Although the invention has been described in detail in connection with the exemplary embodiments, it should be understood that the invention is not limited to the above disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alternations, substitutions, or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Accordingly, the invention is not limited by the foregoing description or drawings, but is only limited by the scope of the appended claims.