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The present invention is directed to a large scale display and more particularly to the LED modules, segments and support structure for a large scale LED display.
Large scale displays on the order of 10×20 ft. or 40×60 ft. are known to employ a net formed of intersecting cables to structurally support a number of pixel units as shown in Temple U.S. Patent Application Publication No. US 2006/0039142 A1. Because of its flexible nature, this net display may be supported on curved or irregular surfaces as well as flat surfaces. However, this net display is so flexible that the pixel units can twist about the cables, impairing the visibility of the pixels. Moreover, the horizontal cables of the net flex so that the pixel units become misaligned resulting in distortions in the displayed image. The pixel units of this net display include a housing for a circuit board that supports a cluster of red, green and blue LEDs wherein a potting material seals the circuit board from the environment. U.S. patent Yoksza et al. U.S. Pat. No. 5,410,328 shows similar pixel modules for a large scale LED display wherein each module is individually removable from the display by removing a few screws or twisting the module. One wall of the housing of the pixel module in Yoksza et al. extends beyond the LEDs so as to provide a sunshade for the module. Another LED module for a display, as shown in U.S. patent Simon et al. U.S. Pat. No. 4,887,074, uses a heat sinking potting compound in contact with the circuit board supporting the LEDs and heat spreader plates to dissipate heat from the module housing.
In accordance with the present invention, the disadvantages of prior art large scale LED displays have been overcome. The LED display system of the present invention includes a novel support structure for a number of LED modules wherein the support structure is sufficiently flexible so that the display can conform to curved or irregular surfaces and yet the support structure has sufficient structural integrity to prevent twisting and sagging of the LED modules, preventing misalignment of the modules so that a distortion free image can be displayed.
In accordance with one feature of the present invention, the display includes a plurality of LED modules wherein each LED module includes a module housing that supports a plurality of color LEDs. The support structure for the LED modules includes a first pair of parallel cables; a first set of rigid links, extending between the cables of the first cable pair; a second pair of parallel cables, the cables of the second cable pair being parallel to the cables of the first cable pair; and a second set of rigid links extending between the cables of the second cable pair wherein each of the LED modules is mounted on one cable of the first cable pair and one cable of the second cable pair.
In accordance with another feature of the present invention, the rigid links are H-shaped links that are over-molded onto a pair of cables. The links are such that they locate the position of the LED modules along the cables.
In accordance with another feature of the present invention, the support structure includes a plurality of plates wherein the plates are mounted on one cable of the first cable pair adjacent to at least one rigid link of the first set and on one cable of the second cable pair adjacent to at least one link of the second set wherein a LED module is removably mounted on a plate.
In accordance with still a further feature of the present invention, a LED module for a display includes at least two red LEDs; two green LEDs; two blue LEDs; a circuit board on which the LEDs are mounted and an over-molded housing encasing the circuit board, the LEDs protruding from a front surface of the housing and the front surface of the housing including a plurality of heat sink fins.
In accordance with another feature of the present invention, a LED display comprises a plurality of linear segments of LED modules in each of a plurality of columns or rows of the display, each LED module having a housing supporting a plurality of multi-color LEDs and each segment including a plurality of LED modules coupled together so that the LED modules of a segment are removable from the display only as a group and each segment of LED modules is removable from the display independent of the LED modules of another segment. In this embodiment the LED display may include individual LED modules that are connected between segments of LED modules.
In accordance with another feature of the present invention, a segment of LED modules for use in a display comprises a first electrical connector fixedly attached to a first end of the segment; a second electrical connector fixedly attached to a second end of the segment; a plurality of spaced LED modules connected between the first electrical connector and the second electrical connector, the spaced LED modules being connected end-to-end by at least one cable capable of carrying power and/or data to each of the LED modules; and a further cable connected directly between the first connector and the second connector for carrying data directly between the first and second connectors.
These and other advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.
A large scale LED display 10 in accordance with the present invention, as shown in
Each pixel of the display 10 is generated by a module 12 or 14 having two red LEDs 16, two blue LEDs 18 and two green LEDs 20 mounted in a respective housing of the modules 12 or 14 as shown in
There are two types of pixel modules employed in the display 10, master LED modules 12 and slave LED modules 14. Each master module is associated with a group of slave modules in a segment 24 of the display. Although
The support structure for each of the LED modules 12 and 14 of the display 10, as shown in
In a preferred embodiment, the links 28, 34, 38 are H-shaped links that are over-molded onto the cables of each cable pair. More specifically, the two cables of a cable pair are placed in a mold into which plastic is injected around the cable to form the rigid H-shaped links connecting the two cables of a pair. A reel to reel molding process is employed in which the over-molded links are indexed through the mold and the previously molded links are used to datum and position the subsequent links. The molding process ensures that the spacing between the links along the length of the cables is constant. The H-shaped links are used to precisely and easily locate the LED modules along the lengths of the cables so that the spacing between the LED modules in a column and the spacing between the LED modules in a row of the display 10 remains constant. Moreover, the H-shaped links provide structural integrity to the cable support structure of the display 10 to prevent sagging and misalignment of the LED modules when the display is in use. It is noted that the cables are preferably steel cables that are of a gauge sufficient to bear the load of all of the LED modules in a column of the display 10.
More particularly, as depicted in
Both the master LED modules 12 and the slave LED modules 14 are removably mounted on the respective back plates 42 and 44 so that the individual master LED modules 12 and/or a slave module segment 54 can be removed and replaced after the display 10 is installed. As seen in
As seen in
The master LED module connected to the slave LED module segment 54 via the connector 56 provides data and power to the slave LED modules 14 of the segment 54 via the ribbon connector 60. A LVDS cable 88 that extends from the first electrical connector 56 and the second electrical connector 58 provides a direct electrical connection between a pair of master LED modules 12 and 12′ of adjacent segments 24 in a column of the display 10 to allow the master LED modules of adjacent segments in a column to communicate directly as discussed in detail in the copending patent application Ser. No. ______ entitled “Data And Power Distribution System And Method For A Large Scale Display,” filed concurrently herewith and incorporated herein by reference. Adjacent master LED modules 12 and 12″ in a row of the display 10 communicate directly via a flex cable 90. In a preferred embodiment, the flex cable 90 overlies a H-link 34 connecting the support cables 32 and 30 as depicted in
Each of the slave LED modules 14 includes a housing 100 that is over-molded about the slave module printed circuit board 102 on which the LEDs of the module are mounted and about a portion of the ribbon cables 60 connected to the printed circuit board 102 by a IDC connector 104. Each slave LED module is connected to the ribbon cable in a common-bus manner so that a failure of any connection does not affect the other slave modules. In order to over-mold the housings of the slave LED modules 14, a string of, for example, fifteen printed circuit boards 102 supporting the LEDs for respective slave modules are placed in a mold wherein the fifteen printed circuit boards are connected by respective ribbon connectors 60 in a string. Thereafter, a thermoset or thermoplastic resin is injected into the mold to form a casing or housing 100 about the printed circuit boards 102 and ribbon connectors 104. The over-molded housing of the LED modules provides extremely robust modules that can withstand harsh outdoor weather. Prior to injecting the resin to form the housing 100 of the slave LED modules 14, a flash memory contained on the circuit board 102 is programmed with the address of the slave LED module. For a slave module segment 54 having fifteen slave LED modules, the slave modules will have an address of 1 to 15 starting in sequence with the slave LED module that is closest to the electrical connector 56 to be attached to the master LED module that will control the slave modules in a segment 24 of the display. It is noted that, while the printed circuit boards are in the molding fixture, the electronics on the boards 102 can be tested prior to over-molding. It is noted, that the mold for the slave LED module housings supports the printed circuit board 102 for the LEDs at a 10° angle from the back surface 106 of the housing. As such, when the slave LED module segment 54 is mounted vertically, the LEDs are angled downward by 10° for better viewing of the pixels generated by the slave modules when the display is in use. It should be appreciated, however, that the angle of the LEDs can be 0° to 20° where the LEDs are angled up, down or to the side depending upon the use of the display.
Each of the housings 100 for the slave LED modules 14 has integrally formed heat sink fins on a front surface of the housing between a first column 112 of red, green and blue LEDs and a second column 114 of red, green and blue LEDs. Placing the heat sink fins 108 between the LEDs of the module, which are actuated to form a single pixel, does not interfere with the light generated by the LEDs to form the pixel. It is noted, in a preferred embodiment, the LEDs in the first column have an order of red, green and blue; whereas the LEDs in the second column have an order of green, blue and red so as to provide better color mixing to generate the various colors of a pixel.
Each of the housings 100 for the slave LED modules 14 also has integrally formed sunshades 110 that project outwardly above each of the LEDs 16, 18 and 20. It is noted, that in an alternate embodiment that does not have the heat sink fins 108 on the front surface of the housing 100, one sunshade 110 may be positioned above each row of LEDs. The sunshades 110 as well as the black or dark resin used to form the housing 100 of the LEDs enhances the contrast or conspicuity of the pixels generated by the modules 14 when the display 10 is used outdoors.
As shown in
The housing 124 for each of the master LED modules is over-molded about the master module printed circuit boards 126 and 128. The LEDs 16, 18 and 20 for the master module 12 are mounted on the printed circuit board 126 which is similar to the printed circuit board 102 of the slave LED modules for controlling the illumination of the LEDs of a module. The printed circuit board 128 of the master LED module includes additional circuitry for controlling the functions of the master LED module that are unique thereto, such as extracting the data intended for the master module and its associated slave LED modules in a segment 24 of the display as described in the co-pending patent application Ser. No. ______, entitled “Data and Power Distribution System And Method For A Large Scale Display,” filed concurrently herewith and incorporated herein by reference. In a preferred embodiment, the printed circuit board 126 is soldered to the circuit board 128 at a 10° angle so that when the boards 126 and 128 are placed in the mold for the master LED module housing 124, the LEDs 16, 18 and 20 will be at a 10° angle to the back surface 130 of the module 12 as described above for the LEDs of the slave module 14.
The front surface of the housing 124 for each of the master LED modules 12 is the same as the front surface of the housing 100 for the slave LED modules 110 so that both types of modules have the same LED order, the same heat sink fins 108 and the same sunshades 110, providing a uniform appearance of pixels throughout the display regardless of whether they are generated by a master or a slave module. However, the sides and the back surface 130 of the master LED module housing 124 are different than those of the housing 100 for the slave modules 102. In particular, the sides 129 and 131 of the master module housing 124 are formed with projections 132 having apertures 134 therein for the screws 78 that attach the master LED module 12 to the back plate 42 of the master LED module. The back surface 130 of the master LED module housing 124 includes a number of integrally formed heat sinks 136 so as to further aid in the heat dissipation of the master module. It is noted that the housings for the master LED modules as well as the housings for the slave LED modules are over-molded with a thermally conductive resin. The resin conducts heat away from components and the geometry of the housing spreads the heat and provides a maximized surface area for heat transfer. Moreover, the back plate 42 is thermally and electrically connected to the ground plane on the master LED module's printed circuit board to allow the back plate 42 to act as an additional and independent heat sink for the master LED module.
The back surface 130 of the housing 124 of the master LED module 12 is also formed with two pairs of grooves 138 and 140 through which power cable connectors 142 and 144 extend. When power cables 118 and 120 are seated in the grooves 138 and 140 of the housing 124, the prongs of the connectors 142 and 144, pierce the rubber insulation of the power cables so as to make electrical contact with the cables. The power cables are continuous and the insulation piercing connectors 142 and 144 are formed with sharp prongs to minimize the force required to penetrate the rubber insulation on the cables. The preferred insulation is a thermoplastic elastomer because of its resilience and toughness. This insulation tends to close around the penetrating prongs forming a seal. It is noted that when the screws 78 that attach a master LED module 12 to a back plate 42 are tightened, the prongs of the connectors 142 and 143 are driven into the power cables. A redundant set of power connections are provided for the master LED modules so that there are two positive and two neutral connections spread apart as far as possible such that the system is tolerant to a connection failure. The master LED module 12 also includes Z-axis connectors 148 and 150 surrounded by elastomeric pads 152. These connectors are commercially available flexible connectors that are designed to conduct along a single Z-axis. The back plate 42 compresses the Z-axis connector between contacts on the printed circuit board 128 and contacts on the flex circuit 90. The flex circuit 90 is designed as a stripline circuit with conductors and conductor spacing adjusted to achieve the desired impedance (75 ohms). The stripline configuration also provides shielding for the data conductors. The Z-axis connectors connect to the flex cables 90 so as to allow adjacent master LED modules 12 in a row of a display panel to communicate directly as discussed above.
In accordance with a preferred embodiment of the present invention, the display 10 is arranged in a number of panels for easy deployment. Each panel, may have, for example, sixteen columns wherein a full height panel has 480 rows, although, each of the display panels can have any height and width desired. The support cables, 24, 26, 30, 32, 36 and 40 for the LED modules of each display panel are attached to a steel bar 60 wherein each of the steel bars 160 of a display 10 are clamped together to support the multiple display panels forming the display 10. The steel bar 160 is then attached to a support structure 162 which is used to hoist the display 10 on to a support structure such as a building or frame. Each of the display panels forming the display 10 includes a data hub 164 that provides the video data to the display panel of the display 10. Power to the display panel 10 may also be provided to the display 10 through the data hubs 164 so that the data hubs can monitor the power supply. Details of the data hubs and power hubs for the display 10 are disclosed in the co-pending patent application Ser. No. ______, entitled “Data And Power Distribution System And Method For A Large Scale Display,” filed concurrently herewith and incorporated herein by reference.
The large scale LED display of the present invention is extremely robust, readily repairable and suitable for outdoor as well as indoor use. Many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as described hereinabove.
The present application is related to co-pending patent applications U.S. Ser. No. ______ entitled “Data And Power Distribution System and Method For A Large Scale Display;” U.S. Ser. No. ______ entitled “Enumeration System And Method For A LED Display;” and U.S. Ser. No. ______ entitled “Large Scale LED Display System,” each filed concurrently herewith.