March/April 2008
From the largest televisions to the smallest cell phones, flat-panel displays are cornering the electronics marketplace. As consumers begin to discard these viewing devices, electronics processors must consider the benefits and potential challenges of recycling them.
By Betty Patton
From the question "What's on the tube?" to the popular online video site YouTube, people have long considered television and the cathode-ray tube—its traditional display technology—one and the same. That's rapidly changing, though, as flat-panel displays begin to overtake CRTs' decades-long domination of the television and computer-monitor market.
The boom in flat-screen televisions is in large part due to the U.S. Digital Transition and Public Safety Act's requirement that television broadcasters stop analog transmissions and replace them with digital ones by Feb. 17, 2009. To continue to receive broadcasts after that date, a television must contain a digital tuner or be connected to a converter box or a digital cable or satellite service. (Manufacturers began installing digital tuners in televisions around 2004. Most older TVs and some built between 2004 and March 2007 will need a converter.)
Many consumers will opt to replace older televisions rather than purchase a converter box. Though newer televisions of all varieties contain digital tuners, flat screens have become consumers' display of choice due to their compact design, light weight, higher resolution, and better clarity in both high- and low-light environments. Research advances in flat-screen technologies have led to lower production costs and lower prices, fueling the market. Experts predict that flat-panel displays will be 81 percent to 85 percent of the electronic display market by the end of this year and 94 percent or more of the market by 2013.
In addition to their use as televisions and laptop and desktop computer monitors, flat-panel displays are in cell phones, digital cameras, and other consumer electronics; industrial and medical monitoring equipment; and a list of other applications that continues to grow. As users begin to discard these products, electronics recyclers are wondering about their potential reuse, refurbishment, and recycling.
The Technology
Most flat screens use one of two technologies: liquid crystal display (about 85 percent of the market) or plasma screen (13 percent), with other technologies accounting for the remaining 2 percent. LCDs constitute the majority of computer monitors and nearly 50 percent of flat-screen televisions, typically the small- to medium-sized ones. LCDs also proliferate in handheld or battery-powered electronics because of their light weight and low energy use.
The LCD screens in today's consumer products are of the active-matrix, thin-film transistor variety, or TFT LCDs. They are constructed like an 11-layer sandwich in this order: polarizer, glass substrate, indium tin oxide, thin-film transistor, orientation film, liquid crystals, orientation film, indium tin oxide, color filter (in color devices), glass substrate, and polarizer. In most LCDs used for computer monitors, televisions, and other display devices, one or more fluorescent bulbs illuminates the LCD from behind.
LCD screens are steadily growing larger in terms of viewing area. The average desktop computer monitor has 6 percent more display area than it did in 2005; laptop and notebook computers have about 4 percent more display area. Until recently, manufacturers could use LCD technology only in screens measuring less than 40 inches diagonally. Now companies are creating displays of up to 108 inches across. As dimensions increase, though, so does the need for backlighting, thus larger units have more fluorescent bulbs.
Large-screen televisions, plus some industrial and medical monitoring applications, are more likely to use plasma technology. Compared with LCDs, plasma screens are heavier and use more energy. They're also more expensive, minimizing their appeal in the small- to medium-sized display market, but their prices are more competitive in the big-screen TV arena. Even so, with LCDs' advances in screen size, analysts predict plasma screens' market share in large-screen displays will slip to 7 percent by 2009.
Plasma displays require no external lighting—the illumination comes from phosphors that are electrically excited between two glass panels. (Plasma phosphors are identical to those in CRTs.) A plasma screen's layers are face glass plate, dielectric layer, transparent electrode, protection layer, RGB phosphors, dielectric layer, address line, and spacer.
Material Matters
Flat-screen displays contain many of the same materials as CRTs and other electronic products, with a few important exceptions. They all contain ferrous and nonferrous metals, plastic, glass, printed circuitboards, and wiring in quantities that vary greatly from product to product. In general, LCD and plasma monitors contain less glass and less lead than CRTs. LCD screens, by definition, contain liquid crystals. Color LCD screens also contain cold cathode fluorescent lamps, which—like all fluorescent lamps—contain a small amount of mercury. The amount of mercury varies by product size and model, according to the Electronic Industries Alliance: up to 5 milligrams in devices with small screens such as cameras and cell phones; up to 50 mg in a laptop computer, flat-screen computer monitor, or flat-screen television. (In comparison, an automobile mercury switch contains about 1 gram of mercury, which is 20 times that of a 50-mg LCD screen.)
As color LCD devices begin to appear in significant quantities in the recycling stream, the fluorescent lamps will pose a challenge to electronics processors. The lamps are small and fragile, and their location in a device varies from product to product. Because most shredders are not designed to contain mercury, recyclers must locate and carefully remove the lamps before the product enters the shredder, which is no easy task, and carefully package and transport them to a company that specializes in fluorescent lamp and mercury recycling.
The liquid crystals in LCDs are, for all practical purposes, not reclaimable with current technology. Separating them from the glass requires the extensive use of solvents, at an exorbitant expense, for the reclamation of a miniscule amount of crystals by weight. Further, each display device contains about 25 unique crystals out of a possible 300 on the market. To reuse them for their original purpose, recyclers would need to separate them by type or—because most of these liquid crystal "soups" are patented—by manufacturer.
Glass panels constitute 80 percent of the weight of an LCD display device, with the device's technology dictating what type of glass it contains. Smaller, monochromatic displays have soda-lime glass with a melting point of about 1,000 degrees C. Color monitors and televisions have borosilicate glass with a melting point of about 1,150 degrees C. Both kinds of glass are recyclable: Manufacturers can melt it, remove and discard the liquid crystals and other contaminants, and use the glass in ceramics. This glass can't be turned back into a flat-panel display, however.
Potentially more valuable than the glass in an LCD screen is the indium tin oxide sandwiched between the glass layers. Indium is a fairly rare metal extracted from zinc ores. As LCD-screen manufacturing grows, so does demand for indium, making its recovery all the more important. Sharp Electronics (Osaka, Japan) has developed a fairly simple method for extracting clean indium from LCD glass cullet.
Dismantling, Repairing, and Reselling
Repair, refurbishment, and demanufacturing don't seem to be high priorities in the design of flat-panel displays. Disassembly is labor-intensive and tool-intensive. Every manufacturer has a different assembly process and technique. The connectors holding the device together are small, and one monitor can have dozens of different screws and clips. Further, manufacturers glue many parts together for permanent adhesion.
A 2007 E-Scrap News survey of U.S. electronics processors confirmed that flat-panel display dismantling takes longer than CRT dismantling. On average, these handlers report CRT monitor dismantling takes them 9.2 minutes; LCD dismantling takes 12.8 minutes; and plasma-screen dismantling takes 13.4 minutes. The designed-in barriers to dismantling could make disassembly less attractive to recyclers compared with shredding flat-screen displays and using downstream techniques to separate the various commodities.
Opportunities for repair and refurbishment are few. The fluorescent lamp in a color LCD display is relatively easy to replace, but due to its long lifespan, it's rarely necessary. It's also possible to replace or repair the integrated circuit tabs. But the most common faulty components in an LCD are the display parts—the liquid crystals and the thin-film transistors—and the replacement cost of either one is prohibitive. Though plasma screens are not entering the waste stream in great numbers, they, too, have limited repair options.
Fortunately, the resale market for functioning flat-screen computer monitors appears strong. Further, their lighter weight makes them easier to handle and less expensive to transport compared with CRTs.
A Waiting Game
Electronics processors are probably seeing a trickle of flat-screen devices compared with CRTs, and it might still be several years before significant numbers of them hit the recycling stream. These products are too new to produce any solid lifespan data, but a 2007 report conducted for King County, Wash., estimates that LCD monitors will last 3.6 times longer than CRT monitors. For CRT monitors, the mean time between failures is 12,500 hours. In other words, if it were used 40 hours a week, a CRT would last an average of 6 years, whereas an LCD monitor would last nearly 22 years.
Failure is not the only reason consumers purchase a new computer monitor, however. In laptop computers and other portable electronics, the display is integrated into the product design, thus the display will get discarded when the device to which it's attached fails or when the consumer decides to upgrade. Further, manufacturers often sell desktop computers and display devices as a package. When a consumer decides to replace a central processing unit, a new monitor might come with it, putting functioning, used monitors in the recycling stream.
CRT monitors average four years of life with their first user and two and a half years with their second, according to a 1999 study by the National Safety Council (Itasca, Ill.). If LCD monitor usage is similar but 3.6 times longer, first users potentially could keep them more than 14 years. What's more likely, though, according to an International Association of Electronics Recyclers (Albany, N.Y.) study, is that users will dispose of them to upgrade to newer technology after six or seven years. When flat-screen monitors do get discarded, if their rapidly increasing sales figures are any guide, the volume that hits the recycling stream will increase quickly.
Televisions have a different ownership and use pattern. Many studies estimate that CRT-based televisions last about 15 years. Experts believe flat-panel televisions will have shorter lifespans, but how short they have yet to determine.
Coming Soon
Flat-panel displays will dominate the electronic display market for many years, but research and development in this arena is resulting in new products that will add to the complexity of managing the end-of-life material stream. Right now 2 percent of the flat-screen market consists of newcomer technologies including organic light-emitting diodes, field emission displays, light-emitting diode arrays, and surface-conduction electrometer displays. Many of these have rather narrow applications and are quite expensive to produce, limiting their use in consumer goods.
Closest to wide commercial use are organic light-emitting diode displays, which should turn up in televisions in the near future. OLED devices use electroluminescence to display information, allowing the development of flexible screens. Like LCDs, OLEDs contain indium tin oxide. Unlike LCDs, they don't need backlighting, so they don't contain fluorescent lamps or mercury. Their use of light-producing polymers could add complexity to the material separation process, though.
Ideally, greater public interest in electronics recycling will lead to flat-screen design improvements. The 2007 E-Scrap News survey asked electronics recyclers how manufacturers could better design their products for recycling. Their requests were simple: Make the construction more uniform and label what's in there. Use fewer screws and ones of a uniform size. Use fewer hazardous materials. Label the plastics by resin type, just like consumer containers are labeled. And, most important, make LCD lamps easier to remove by putting them in standard places. Manufacturers concerned about the end-of-life impact of their products can address these issues.
Recyclers still have plenty of questions about flat-panel displays' refurbishment opportunities, recycling potential, and material content. These devices are just arriving in the recycling stream, but they will assuredly continue to do so.
Betty Patton is president of Environmental Practices, a waste and recycling consulting firm based in Portland, Ore. This article is based on research sponsored by E-Scrap News.
From the largest televisions to the smallest cell phones, flat-panel displays are cornering the electronics marketplace. As consumers begin to discard these viewing devices, electronics processors must consider the benefits and potential challenges of recycling them.