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    1. Architectural Lighting
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    White Tetra strips extend GELcore's range for channel letter lighting

    Sept. 27, 2004
    GELcore has added a white LED strip to its GE Tetra range for channel letter applications and has also extended the length of strips operated from a single power supply.
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    Lighting systems manufacturer GELcore recently added white to the range of colors for its GE Tetra product line, which is used as a replacement for neon in channel letters and other architectural lighting applications in markets such as retail, restaurants and hospitality.

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    Figure 1 Tetra systems consist of a strip of rugged LED modules connected by flexible, heavy duty wire to each other and to a power supply (figure 1). In channel letter applications, sign manufacturers typically install these systems into aluminum letter shapes with translucent vinyl facings (figure 2). With the addition of white , GELcore now sells strips with a range of 10 LED colors. "A customer will typically match the color of LEDs and the color of the facing or other enclosure to meet their corporate branding requirements both at night when the sign is lit and also during the day," said Mike DeMarco, Tetra product manager. Figure 3 shows an example of the Tetra product in use in channel letter signage.
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    Figure 2GELcore's white Tetra strip uses blue LED chips in combination with a proprietary GE phosphor. DeMarco says that the industry has had to wait a little longer for white due to technical developments that improved performance and reduced cost. The product has a color temperature around the value of 6500 K typical of white neon tubes with a phosphor coating, since it is easier for sign manufacturers to deal with colors similar to those currently available.

    Rugged design

    One of the principle advantages of LEDs compared with neon is ruggedness and durability, and Tetra has been designed to enhance these characteristics. The Tetra system uses square Piranha LED packages that snap into rugged modules, creating the sign industry's first patented LED design that does not use printed circuit boards. This eliminated the need for added electronic components such as resistors and capacitors. "We look at total potential failure points, and systems that eliminate PCBs and don't have solder points are much less likely to fail in a demanding environment such as an outdoor sign," explains DeMarco.

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    Figure 3Thermal management is achieved via a patented design that uses the connection of the electrical wire to the module to provide a thermal interface, as opposed to using large heat sinks or circuit boards. " This design allows us to underdrive the LEDs so there is less heat to dissipate, which also helps extend LED life," says DeMarco. "The electrical and mechanical connection to the wires provides more than adequate heat sinking."

    Longer runs

    Tetra strips are packaged in reel form and can be cut to any desired length. GELcore also sells splice connectors that allow simple and rapid connection of supply wires to the Tetra strips. Addressing the need for longer runs in some applications, the new GE Tetra XL is capable of operating up to 160 feet of LED lighting from a single 12 V power supply. "This has proved popular with installers and end-users, as it means there will be fewer building or wall penetrations, and installation can be quicker and easier," says DeMarco. "The power supply can be remotely mounted up to 150 feet from the installation, and fewer power supplies can be used in some situations."
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    Figure 4The ability to drive long runs of LEDs is achieved using a 3-wire series-parallel connection system (figure 4). In the standard Tetra system the LEDs are all connected in parallel, and if one of the LEDs fails then the rest stay illuminated. In Tetra XL, groups of 3-5 LEDs are connected in series, and if any LED fails the whole series goes out. "This trade-off is necessary to achieve longer runs," says DeMarco. "However, even losing a series of several LEDs would not be noticeable in many of the large signs used throughout North America, which often use several rows of LEDs." The Tetra XL is particularly appropriate for use as a light engine in the GE Tetra BT, an LED Border Tube system combining Tetra strips and power supplies with housings and lens reflectors . The product is used for exterior and interior border/contour lighting in applications such as petroleum stations and restaurants (figure 5).

    Comparison with neon

    As mentioned above, LED-based systems are much more robust than neon, not only when building the system but also during transportation and installation. Also, rather than replacing entire sections of neon signs, minor modifications can be made on site.

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    Figure 5Critically, LED systems consume about 20% of the power of equivalent neon installations, which combined with long lifetime (Tetra products have a 5-year warranty) results in significant cost savings. LEDs are also low voltage, and do not contain hazardous substances such as mercury found in some neon tubes.

    Another disadvantage of neon is that light is given off in all directions and a large amount is wasted. Although LED systems like Tetra have a much lower lumen output, the light is all directed at the channel letter face rather than at the back or sides of the channel.

    As with any LED system, cost is a major issue. "When end-users look at the complete installed cost, factors like lower labor costs during installation and a lack of breakages weigh heavily for LEDs," says DeMarco. "The cost equation is strongest for warmer colors, and red LED-based systems are virtually on a cost parity with neon."

    LED-based channel letter systems currently have around 5-6% of the market according to a recent survey, and experienced double-digit growth over the previous year. Most of this is for new construction, although DeMarco says that the Tetra system is very well suited for retrofit installations. As the volumes increase and LED prices continue to fall, the advantages of LEDs for this application will ensure that market penetration continues to grow rapidly.