Abstract:
An LED visual display apparatus includes a plurality of LED pixels arranged in a generally rectangular array and each having a substantially identical construction. A controller controls groups of the LEDs to produce virtual pixels. In some instances, the construction of each LED pixel consists of 6 to 9 LEDs, inclusive, includes a plurality of red LEDs, a plurality of green LEDs and at least one blue LED, and has more red LEDs than green LEDs. In some instances, the array includes rows of LEDs that consist only of green and blue LEDs which define a repeating green-green-blue pattern. In some instances, the array includes rows of LEDs that consist only of red and green LEDs which define a repeating red-red-green pattern.

Description:
[0001]     This application claims the priority under 35 U.S.C. §119(e) of co-pending U.S. Provisional Application No. 60/610,291, filed on Sep. 16, 2004 and incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates generally to LED (light emitting diode) display modules and, more particularly, to pixel designs within LED display modules.  
       BACKGROUND OF THE INVENTION  
       [0003]     LED display modules are conventionally used in visual display applications, such as advertising billboards, stadium scoreboards, etc. A typical LED display module includes a generally rectangular array of LED pixels, each pixel including a plurality of LEDs positioned in a desired arrangement relative to one another. Conventional display modules can include, for example, 640 LEDs, and conventional billboards can include, for example, from 100 to as many as several thousand display modules.  
         [0004]      FIGS. 1-6  (and corresponding color  FIGS. 1A-6A ) illustrate in plan view conventional examples of LED pixel structure designs.  FIG. 1  illustrates an eight pixel-by-eight pixel portion of a rectangular array of LED pixels that can be provided on a display module. Each LED pixel P 1  includes a red LED R, a green LED G, and a blue LED B. The pixel structure illustrated in  FIG. 1  is a basic pattern with no resolution enhancement.  
         [0005]      FIGS. 2-6  each illustrate four pixel-by-four pixel portions of generally rectangular LED pixel arrays. All pixels in a given array have the same LED pixel structure design. Each pixel P 2  in  FIG. 2  includes two red LEDs R 1  and R 2 , a green LED G and a blue LED B. Each pixel P 3  of  FIG. 3  includes two red LEDs R 1  and R 2 , two green LEDs G 1  and G 2 , and a blue LED B. Each pixel P 4  of  FIG. 4  includes two red LEDs R 1  and R 2 , two green LEDs G 1  and G 2 , and two blue LEDs B 1  and B 2 . Each pixel P 5  of  FIG. 5  includes four red LEDs R 1 -R 4 , four green LEDs G 1 -G 4 , and two blue LEDs B 1  and B 2 . Each pixel P 6  of  FIG. 6  includes eight red LEDs R 1 -R 8 , four green LEDs G 1 -G 4 , and two blue LEDs B 1  and B 2 .  
         [0006]     Each of the pixel arrangements in  FIGS. 2-6  has associated therewith a characteristic known as pitch, that is, the distance between the geometric centers of adjacent pixels (horizontally and vertically). Examples of typical pitch values in conventional arrangements include 25.4 mm, 38.1 mm and 50.8 mm. Resolution, brightness and other visual characteristics of the pixel arrangements of  FIGS. 2-6  are determined by the pitch and by the various combinations of the number, color and placement of the LEDs within the individual pixel designs.  
         [0007]     In  FIGS. 2-6 , the pixels P 2 -P 6  are shown enclosed in dark-lined square boundary lines. These square boundary lines are shown to enclose a geometric area sufficient to accommodate sixteen conventional LEDs arranged in a four-by-four square array.  
         [0008]     As illustrated at VP 2  in  FIG. 2 , VP 3  in  FIG. 3 , VP 4  in  FIG. 4 , VP 5  in  FIG. 5  and VP 6  in  FIG. 6 , it is known in the art to control the LEDs of an LED pixel array such that one or more LEDs from a single pixel is (are) shared by two or more “virtual pixels”. The centers of such virtual pixels are closer together than the centers of the “physical pixels” P 2 -P 6 . This creates a perceived pitch (or a virtual pitch) that is less than the actual physical pitch or distance between the centers of the physical pixels.  
         [0009]     Taking as an example the virtual pixel boundary framework as conceptually illustrated at VP 2  of  FIG. 2 , the virtual pixels defined by this boundary framework VP 2  have a virtual pitch, illustrated diagrammatically at  200 , that is substantially smaller than the physical pitch of the actual physical pixels P 2 , illustrated diagrammatically at  201 . Each virtual pixel illustrated in  FIG. 2  shares four LEDs with other neighboring virtual pixels. For example, the virtual pixel  20  shares four LEDs with eight virtual pixels  21 - 28  which immediately surround the virtual pixel  20 . Each LED of a given physical pixel P 2  in  FIG. 2  is shared four ways among various virtual pixels. The virtual pixel boundary frameworks VP 3 -VP 6  of  FIGS. 3-6 , respectively, illustrate other schemes for sharing LEDs to create virtual pixels whose virtual pitch is less than the physical pitch of the corresponding physical pixels P 3 -P 6 .  
         [0010]     As mentioned above, the number, color and placement of LEDs within a physical pixel, together with the pitch of the pixel array, affect the various visual characteristics of the pixel array. When LED sharing is used to create virtual pixels as described above, the design of the physical pixels can affect virtual pixel design, and vice-versa.  
         [0011]     It is therefore desirable to provide LED pixel arrays with pixel structure designs that produce desired visual quality and which may also be controlled to produce virtual pixels that provide a desired enhancement in visual quality.  
       SUMMARY OF THE INVENTION  
       [0012]     Exemplary embodiments of the present invention provide an LED visual display apparatus including a plurality of LED pixels that each have a substantially identical construction, including at least one each of red, green and blue LEDs. A support structure supports the LED pixels in a generally rectangular array. A controller controls groups of the LEDs to produce virtual pixels.  
         [0013]     In some embodiments, the construction of each LED pixel consists of a number of LEDs in a range from 6 to 9, inclusive, includes a plurality of red LEDs, a plurality of green LEDs and at least one blue LED, and has more red LEDs than green LEDs.  
         [0014]     In some embodiments, the generally rectangular array includes a plurality of rows of LEDs, and each of the rows consists only of green and blue LEDs that define a repeating pattern of three adjacent LEDs arranged such that a first green LED is followed by a second green LED adjacent to the first green LED, and the second green LED is followed by an adjacent blue LED.  
         [0015]     In some embodiments, the generally rectangular array includes a plurality of rows of LEDs, and each of the rows consists only of red and green LEDs that define a repeating pattern of three adjacent LEDs arranged such that a first red LED is followed by a second red LED adjacent to the first red LED, and the second red LED is followed by an adjacent green LED.  
         [0016]     Before undertaking the Detailed Description of the Invention, it may be advantageous to set forth a definition of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, coupled to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; the term “memory” means any storage device, combination of storage devices, or part thereof whether centralized or distributed, whether locally or remotely; and the terms “controller,” “processor” and “allocator” mean any device, system or part thereof that controls at least one operation, such a device, system or part thereof may be implemented in hardware, firmware or software, or some combination of at least two of the same.  
         [0017]     It should be noted that the functionality associated with any particular controller or allocator may be centralized or distributed, whether locally or remotely. In particular, a controller or allocator may comprise one or more data processors, and associated input/output devices and memory that execute one or more application programs and/or an operating system program.  
         [0018]     Additional definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior uses, as well as to future uses, of such defined words and phrases.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, and in which:  
         [0020]      FIG. 1  illustrates an LED pixel array according to the prior art.  
         [0021]      FIGS. 2-6  illustrate various LED pixel arrays including virtual pixel arrays through LED sharing according to the prior art.  
         [0022]      FIGS. 1A-6A  are respective color versions of  FIGS. 1-6 .  
         [0023]      FIGS. 7-14  illustrate LED pixel arrays including virtual pixel arrays through LED sharing according to various exemplary embodiments of the invention.  
         [0024]      FIGS. 7A-14A  are respective color versions of  FIGS. 7-14 .  
         [0025]      FIG. 15  diagrammatically illustrates an LED display module according to exemplary embodiments of the invention.  
         [0026]      FIG. 16  diagrammatically illustrates an LED billboard apparatus according to exemplary embodiments of the invention.  
     
    
     DETAILED DESCRIPTION  
       [0027]      FIGS. 1 through 16 , discussed herein, and the various embodiments used to describe the principles of the present invention in this patent document, are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably arranged LED sign apparatus.  
         [0028]      FIGS. 7-14  (and corresponding color  FIGS. 7A-14A ) illustrate portions of generally rectangular LED pixel arrays that include corresponding virtual pixel arrays through LED sharing according to various exemplary embodiments of the invention. In any given one of  FIGS. 7-14 , the illustrated pixel array portion is a four pixel-by-four pixel square, and each of the pixels has the same LED arrangement.  
         [0029]     In  FIG. 7 , pixel P 7  in the array includes basically the same red, green and blue LEDs as in the basic arrangement of prior art  FIG. 1 . However, due to the positioning of the LEDs, it is possible to display a higher resolution than when, as in  FIG. 1 , the red, green and blue LEDs are clustered as a triplet and mapped as a single point. The virtual pixel boundary framework VP 7  illustrates the definition of virtual pixels through LED sharing. In the example of  FIG. 7 , each of the red, green and blue LEDs of a given pixel is shared among four virtual pixels as illustrated by the virtual pixel boundary framework VP 7 . The example of  FIG. 7  exhibits a resolution enhancement factor (REF) of 1.35. The REF quantifies the perceived image enhancement provided by the virtual pixel array. If REF=1, there is no resolution enhancement, and the virtual pitch is equal to the physical pitch. If REF=2, this is the maximum possible resolution enhancement, and the virtual pitch is half of the physical pitch, meaning that the virtual resolution is twice the physical resolution.  
         [0030]     Each pixel P 8  in the array of  FIG. 8  includes three red LEDs R 1 -R 3 , two green LEDs G 1  and G 2 , and one blue LED B, arranged as shown. The virtual pixel boundary framework VP 8  shows that, for a given pixel, each of the red and blue LEDs is shared by four virtual pixels, and each green LED is shared by two virtual pixels. For the embodiment of  FIG. 8 , REF=1.75.  
         [0031]     In the arrangement of  FIG. 9 , each pixel P 9  includes four red LEDs R 1 -R 4 , two green LEDs G 1  and G 2 , and one blue LED B, arranged as shown. The virtual pixel boundary framework VP 9  shows that, for a given pixel, each red LED is located generally at the center of a corresponding virtual pixel and is not shared between virtual pixels, each blue LED is shared by four virtual pixels, and each green LED is shared by two virtual pixels. In the embodiment of  FIG. 9 , REF=1.85.  
         [0032]     Each pixel P 10  in the array of  FIG. 10  includes four red LEDs R 1 -R 4 , two green LEDs G 1  and G 2 , and one blue LED B, arranged as shown. The virtual pixel boundary framework VP 10  shows that, for a given pixel, each red LED is located generally at the center of a corresponding virtual pixel and is not shared by virtual pixels, and that each of the green and blue LEDs is shared by four virtual pixels. In the embodiment of  FIG. 10 , REF=1.85.  
         [0033]     Each pixel P 11  in the array of  FIG. 11  includes three red LEDs R 1 -R 3 , three green LEDs G 1 -G 3 , and two blue LEDs B 1  and B 2 , arranged as shown. The virtual pixel boundary framework VP 11  shows that, for a given pixel, the red LEDs R 2  and R 3 , and the green LEDs G 1  and G 2  are shared by two virtual pixels, and that each of the remaining LEDs R 1 , G 3 , B 1  and B 2  is shared by four virtual pixels. In the embodiment of  FIG. 11 , REF=1.8.  
         [0034]     Each pixel P 12  in the array of  FIG. 12  includes four red LEDs R 1 -R 4 , two green LEDs G 1  and G 2 , and two blue LEDs B 1  and B 2 , arranged as shown. The virtual pixel boundary framework VP 12  shows that, for a given pixel, each of the red LEDs R 1 -R 4  is located generally at the center of a corresponding virtual pixel and is not shared by virtual pixels, and that each of the remaining LEDs G 1 , G 2 , B 1 , and B 2  is shared by two virtual pixels. In the embodiment of  FIG. 12 , REF=1.9.  
         [0035]     Each pixel P 13  in the array of  FIG. 13  includes four red LEDs R 1 -R 4 , three green LEDs G 1 -G 3  and two blue LEDs B 1  and B 2 , arranged as shown. The virtual pixel boundary framework VP 13  shows that, for a given pixel, each of the red LEDs R 1 -R 4  is located generally at the center of a corresponding virtual pixel and is not shared by virtual pixels, blue LEDs B 1  and B 2  and green LEDs G 2  and G 3  are each shared by two virtual pixels, and green LED G 1  is shared by four virtual pixels. In the embodiment of  FIG. 13 , REF=1.8.  
         [0036]     Each pixel P 14  in the array of  FIG. 14  includes four red LEDs R 1 -R 4 , four green LEDs G 1 -G 4 , and two blue LEDs B 1  and B 2 , arranged as shown. The virtual pixel boundary framework VP 14  shows that, for a given pixel, each green LED is located generally at the center of a virtual pixel, each red LED is shared by two virtual pixels, and each blue LED is shared by two virtual pixels. In the embodiment of  FIG. 14 , REF=2.0.  
         [0037]     Referring again to the embodiments of  FIGS. 8, 9  and  13 , each of these embodiments includes a plurality of rows of LEDs that define a repeating red-red-green pattern. This can be seen in the LED rows  81  extending left-to-right in  FIG. 8 , in the LED rows  91  and  97  extending from top-to-bottom in  FIG. 9 , and in the LED rows  131  extending from top-to-bottom in  FIG. 13 . In each of these embodiments, the aforementioned red-red-green pattern is repeated along the row, and the pattern is defined by sets of three consecutively adjacent LEDs. In this context, any two LEDs are considered to be adjacent in a given row if there is no other LED interposed between those two LEDs. The red-red-green pattern is illustrated at  82 - 84  in  FIG. 8 , at  92 - 94  in  FIG. 9 , and at  132 - 134  in  FIG. 13 . Note that in  FIGS. 9 and 13  there are two red-red-green rows in each top-to-bottom LED pixel row.  
         [0038]     The embodiment of  FIG. 14  includes a plurality of rows of LEDs that define a repeating green-green-blue pattern that is generally similar to the red-red-green pattern described above with respect to  FIGS. 8, 9  and  13 . This green-green-blue pattern can be seen in the LED rows  141  and  147  extending left-to-right in  FIG. 14 . The green-green-blue pattern is repeated along the row, and the pattern is defined by sets of three consecutively adjacent LEDs. As described above, any two LEDs are considered to be adjacent in a given row if there is no other LED interposed between those two LEDs. The green-green-blue pattern is illustrated at  142 - 144  in  FIG. 14 . Note that there are two green-green-blue rows ( 141  and  147 ) in each left-to-right LED pixel row of  FIG. 14 .  
         [0039]     The embodiments of  FIGS. 8, 9 ,  10  and  13  each include rows that consist only of green LEDs. Examples of all green LED rows are indicated at  95  and  105  in  FIGS. 9 and 10 , respectively. Two different all green LED rows are shown at  85  and  87  in  FIG. 8 , and at  135  and  136  in  FIG. 13 .  
         [0040]     In each of the embodiments of  FIGS. 8, 9 ,  10 ,  12  and  13 , the LED pixel construction includes more red LEDs than green LEDs. The LED pixels P 8  of  FIG. 8  each include six LEDs, three of which are red and two of which are green. The LED pixels P 9  of  FIG. 9  each include seven LEDs, four of which are red and two of which are green. The LED pixels P 10  of  FIG. 10  each include seven LEDs, four of which are red and two of which are green. The LED pixels P 12  of  FIG. 12  each include eight LEDs, four of which are red and two of which are green. The LED pixels P 13  of  FIG. 13  each include nine LEDs, four of which are red and three of which are green.  
         [0041]     The embodiments of  FIGS. 8, 9 ,  10  and  12  include rows that consist entirely of red LEDs. Examples of such all red LED rows are illustrated at  86 ,  96 ,  106  and  126  in  FIGS. 8, 9 ,  10  and  12 , respectively. In addition, the embodiment of  FIG. 10  includes all red LED rows extending in both the left-to-right and the top-to-bottom directions. The top-to-bottom all red LED rows in  FIG. 10  are designated at  107 .  
         [0042]      FIG. 15  diagrammatically illustrates an LED display module according to exemplary embodiments of the invention. The LED display module  150  includes a support panel  151  which supports thereon a plurality of LED pixels  152  arranged in a generally rectangular array. In various embodiments, the LED pixel structure illustrated generally at  152  can be any one of the LED pixel structure designs illustrated at P 7 -P 14  in  FIGS. 7-14 , respectively.  
         [0043]      FIG. 16  diagrammatically illustrates an LED billboard apparatus according to exemplary embodiments of the invention. The LED billboard  160  includes a plurality of LED display modules  150 , such as described above with respect to  FIG. 15 . A billboard structure  161  supports the LED display modules  150  in a generally rectangular array. Other embodiments support the display modules  150  in other array shapes. An LED control system  162  is coupled to the LEDs of the LED display modules  150 , and is responsive to data and control inputs  163  and  164  for controlling operation of the LEDs in the various LED display modules. The LED control system  162  can control the LEDs appropriately to implement virtual pixel arrays such as those described above.  
         [0044]     The foregoing has outlined the features and technical advantages of the present invention so that those skilled in the art may understand the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiments disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.