Product Group Report: TFT Screens

Transcription

1 Product Group Report: TFT Screens An assessment of the remanufacture of Thin Film Technology (LCD) displays. Written by: John Morrell Date: 2006 (reissued May 2009) Page 1 of 15

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3 Contents 1 Overview 4 2 The product CRT Flat panel technologies 7 3 Remanufacturing issues 10 4 Markets 13 5 Environmental benefits 14 6 Conclusions 15 Page 3 of 15

4 1 Overview The growth of Liquid Crystal Display (LCD) and Plasma screens has been rapid over the last five years with the sales of flat screen out selling the tradition Cathode Ray Tube (CRT) screen computer monitor and TV s in CRT screens are rapidly in decline due to their size, weight and power consumption. CRT technology (the last of the initial electronic valve technology that has been superseded by the transistor in all other areas) was on the market mainly for TV s in the beginning, but with the growth of the computer PC market the CRT monitor has been developed with the latest screens being nearly, but not quite, flat. The truly flat screens have taken over from the CRT screens, although similar to look at, LCD and Plasma screens are technically different with Plasma screens mainly used on diagonal screen sizes over 45. This report is concentrating on stand-alone screens for TV s and monitors. LCD screens are widely used in any product that needs a visual display and can be seen in most electronic products from mobile phones to gaming machines. The growth in the TV market has continued and LCD monitors has revitalised a flagging computer market. LCD screens can be used as combined TV and computer monitors with the next development being HDTV and multi media systems that will continue the growth in new flat screen sales for the foreseeable future. Table 1 shows the static computer market in the UK and Table 2 the growing TV market. (Source Keynote) Table 1: Forecasted computer sales UK Sales ( M) 5,861 5,689 5,632 5,599 5,549 % Growth year/year 3% 1% 0.50% 1% Table 2: Forecasted TV sales UK Sales ( M) 1,700 1,750 1,900 % Growth year/year 3% 9% Currently there are a very few of either LCD or Plasma screens being removed from the marketplace and it will be sometime before significant numbers become available for remanufacture. Upgrading generally occurs as households move their main TVs into less communal spaces such as bedrooms. Historically, this has set the rate of replacement. Page 4 of 15

5 Even the older CRT screens are not being discarded as most are used as second/third TV in the home with high percentages of home have two or more TV s as shown in fig. 3 (source TGI BMRB International Ltd 2003). This is the biggest form of reuse with items of electrical / electronic equipment being recycled within the circle of family and friends. Table3: Number of TV s per home TV per home None 2.80% 1 TV 23.30% 2 TV's 36.60% 3+ TV's 37.70% The UK markets for remanufactured flat screens, both LCD and Plasma, being are active for both the home and office markets. Plasma screen prices are still high and likely to remain so, thus increasing attractiveness of remanufacture. LCD screen prices are dropping rapidly as volume and screen size increase. Monitors (up to 17 ) are already only viable if minimal remedial work is required. Towards the end of 2006 the first LCD monitor for under 100 on the high street was seen. In 2009 over 19 can be bought for less. Markets for CRT screens within the UK are negligible: The clear user advantages and lower powers make LCD more attractive even for whole remanufactured PC systems. Markets do exist for CRT monitors overseas in areas like Africa or Eastern Europe which CRT monitors are being sold as part of complete computer systems for 1.50 each. Remanufacture could not be sustained even at this price. Manufacturers like Hewlett Packard (HP) take a responsible view of returning products when customers upgrade their products and offer a trade in programme. Depending on the product there are either remanufactured as a complete unit, broken into components to be used as spares, with the rest recycled to minimise landfill. Dell operates similar services. The USA has a Pass it on programme sponsored by the leading computer companies. LCD screens are checked and sold at a reduced price to charities. There is also an ebay section called rethink which allows suppliers and customers to meet, but this is also based around the US market. 2 The product Although CRT screens are not viable for remanufacture, both Plasma and the larger LCD screens are to some extent viable. There are some technical issues Page 5 of 15

6 with both or them that limit the yield from returned units. The next section provides an overview of the technical makeup of each of the three types of screens: 2.1 CRT CRT screens are the most enduring form of vacuum valve technology that preceded today s semiconductor systems. They consist of a conical glass body, flattish at the base with a neck at the apex. The base (the screen surface) is coated internally with tricolour phosphors (for colour sets) which glow when struck by an electron beam which emanates from an electron gun in the neck. Figure 1 is a simplified representation. Electromagnets cause the beam to scan the front screen in rows to build up an image. Colour screens use three firing guns mounted in the neck, which are synchronised to activate only their pertinent phosphor. Figure 1: Cross-section of a CRT assembly Since the first screens were invented they have gotten bigger with higher resolution and clarity, but they are bulky, heavy and susceptible to screen burn (a persistent image on the screen when the beams have portrayed a fixed image, such as a logo, for a long period). The failure modes are either internal when gun or phosphor failure occurs which is impossible to correct; or externally due to coil failure. These are complex elements which do not justify replacement either. Disposal of CRTs poses a health risk due to the high lead content of the glass. Until 2006 the UK had been disposing of two million tubes requiring segregation. More recently, the industry has been scandalised due to the careless export dumping of EEE waste in developing countries exposing locals to unacceptable hazards. Page 6 of 15

7 2.2 Flat panel technologies Both LCD (or TFT) and plasma types are based on dividing up the screen into small dots of information called pixels. A standard number of pixels for a screen in 2006 was 720 pixels horizontally and 576 pixels vertically. Double this is common in Both LCD and Plasma screens have connector tabs along their horizontal and vertical sides that activate the pixels that make up the display. Figure 2 shows a connector tab with 50+ screen terminations. With the development of the better displays for both TV s and monitors the connector pitch is decreasing, making them more difficult to remove and replace. Figure 3: Flat screen connector tab (inset) and electronics Picture courtesy of the Calyx group In fact if remanufacturers wished to replace edge tabs it would have to be under clean room conditions. Today s technologies are not amenable to replacement because tabs stretch when heated. Similarly screen faults are irreparable even during manufacture. However, repair of ancilliaries such as power supply, backlight and PCB are possible. Figure 3 shows a typical flat screen set up. Page 7 of 15

8 Figure 3: Typical flat screen arrangement The advantages of LCD/Plasma screens over CRT screens are: Smaller footprint saving desk space. Lightweight. Less glare than most CRT screens. Less power consumption. No potential for harm from radiation. Smaller viewing angle to protect data. The disadvantages are: Small viewing angle making it difficult to share information. Built in speakers are inferior due to size. LCD LCD technology was first discovered in the 19 th century, but it took over 100 years before it was commercialised. LCDs comprise a sandwich of liquid crystal between two layers of coated and polarized glass (Figure 4). Applying a voltage causes the crystals to flip between polarized states. Under these conditions the sandwich becomes either transparent or opaque to a light the backlight which shines through (Figure 5). Scaled up to a display screen, the display comprises a matrix of pixels, each of which has can be activated by applying a voltage to the electrodes sited on the vertical and horizontal planes via the connection tabs fixed to the LCD screens to create the required picture or text. Figure 4: LCD basic structure Figure 5: LCD switching mechanism Page 8 of 15

9 In 2006 LCD screens were expensive compared to plasma over 40. In 2009, this is no longer the case, and LCDs are arguably the preferred option in low light conditions. LCDs are not subject to the phosphor burn-in effect. The only component that might wear out is the backlight, which can be replaced. Manufacturers claim between 50,000 to 75,000 hours of service for LCD s whereas plasma screens, even if looked after carefully, will only last around half that time. Page 9 of 15

10 Plasma Plasma screens were developed in the 1960 s and work by placing a high voltage across a low-pressure inert gas causing it to emit light (Figure 6). The gas ionises to plasma, emitting ultraviolet radiation that excites a phosphor coating. (This is a similar principle to a fluorescent lamp.) Like the LCD screens the screen is made up of pixels. However, because of the phosphor, like CRTs they are subject to screen burn-in. Figure 6: LCD switching mechanism 3 Remanufacturing issues The following issues with remanufacture have been discerned from discussions with remanufacturing companies: CRT CRT screens are now considered old technology in the UK. Monitors are virtually unsellable, the few outlets being schools and charities. TVs are still tradable through charities in their high street outlets, but the majority are retained within a family and recycled into bedrooms until they are broken and beyond remanufacture. CRT monitors are being collected by Social Enterprise companies and shipped as-seen overseas to developing countries in Eastern Europe and Africa. The price per unit is 1.50 with a few larger monitors going for 4.50, too low for remanufacturing! LCD/Plasma Plasma screens are sold new at a price that makes it viable to remanufacture (2006), but their novelty means that few are available to justify building a business based on it. The trend for TV s to be replaced and the old unit retained within the home will mean it will be 10 years (past 2010) before the marketplace Page 10 of 15

11 sees significant numbers of LCD or plasma screens coming for remanufacture. Although not widely advertised by manufacturers, early designs of plasma screen are very susceptible to screen burn and will most likely not be suitable for remanufacture. Approx 40% of flat screens returned is rejected due to screen damage and pixel failures. Screen damage is irreparable, but backlight failures and other electrical/electronic faults may be recoverable. In 2009, the price of LCDs per m 2 is falling rapidly, acting as a barrier to remanufacture. However, average screen size is increasing holding the value of a purchased unit. In 2009, an emergent technology is LED screens which offer even lower power and longer life with no issues associated with mercury in the fluorescent back-lights. It may be that the end-of-life LCD is a transient one! Testing is relative easy with TV s connected to a supply and signal generator and monitors connected to a computer system. Remanufacturing will be very dependant on recovery systems which prevent further damage once discarded. Figure 7 shows the basic process to remanufacture screens. At least 50% of incoming screens will be rejected as unsuitable. The process starts at the goods in area where the screen will be separated with CRT screens either sold overseas or recycled. The LCD and Plasma screens are inspected for damage and any severely damaged screens will also go for recycling. The screens that pass this stage will be tested. All screens with pixel faults with be recycled leaving those either working or with minor faults. The screens with minor faults will be repaired and sent for cleaning with the working screens. The screens discarded with screen faults can be scavenged for parts to repair other screens before they are recycled. Before the screens are cleaned and packed they must be PAT (Portable Appliance Test) tested for safety and earth faults and issued with a pass sticker. Logistics costs can have a large impact. Ideally remanufacture is close to sources and to customers and perhaps best suited to an integrated IT outsourcing unit. Figure 7: Remanufacturing process workflow Even if whole products cannot be remanufactured, there is also the opportunity to cannibalise and remanufacture sub-systems or components of the product to feed the after sales service sector; this is always looking for less expensive supplies of spare parts for customer machines. It forms a thriving market with Page 11 of 15

12 companies like Hewlett Packard having a dedicated operation in the Netherlands which is able to remanufacture up to 10,000 parts per month. Page 12 of 15

13 4 Markets The different types of screen are better suited to different applications, as shown in Table 4. Table 4: Display type and application CRT LCD Plasma TV TV TV Monitor Monitor Information Display Information Display Information Display Realistically, standard size remanufactured screens will be applicable mainly to the home and personal use markets. Business office use is unlikely due to bulk purchasing and standards; schools and other institutions are likewise on preset contracts, possibly PFI, and are commonly in receipt of grants for new purchase, or perhaps free issue. Taking each type of screen: CRT No market worth talking of. Perhaps some donation through charities. LCD Computer monitors can be sold as part of a system as long as the spec is relatively up to date. This will mean only return systems requiring very little repair with be viable for remanufacture. Remanufactured LCD TV s will be attractive to most market sectors, but with high price sensitivity. Plasma With the increase in size and performance of LCDs, the attractiveness of plasma is declining in the household market. A market might exist in cost-conscious buyers of public information displays: small retailers and the like. Major business users are almost certain to buy new. Screen burn-in will always be a concern. Page 13 of 15

14 5 Environmental benefits For simple repairs, the notional benefits of remanufacture are relatively straightforward, as shown in Figure 8. This report indicates that more complex repairs to screen construction are technically infeasible, and would most likely entail the bulk of the processing of new manufacture. An interesting issue with flat screens is that the manufacturing energy is on the whole higher than a CRT, largely due to the complex chemicals employed. Even though power per m 2 of display is lower than CRT, buyers are tending to up-size on replacement, negating these benefits. In reality, therefore, the case for replacing a well-functioning CRT is not clear cut! Figure 8: Impacts of manufacture and remanufacture The legacy issues of CRTs have been described previously, but LCDs are not problem-free. The back-lights contain a small amount of mercury and the liquid crystal (LC) itself is toxic. On the other hand the amounts are small and they do not attract a large degree of regulatory attention. However, there are prudent attempts to consider recycling and reuse strategies in advance of the growing waste stream. One project sponsored by the Technology Strategy Board has considered both theses approaches. One problem with LC is that the composition is bespoke to each manufacturer even each model for the application and balance of properties. It is not clear that a usable resource is available simply by pooling recovered liquids. Some downgrading of the application would be inevitable. Other approaches considered included slicing out displays to remove the edge tabs with replacement by a new tab to produce a screen-sized single pixel unit. These could then be mounted in an array to form a new mega-display suitable for public concerts and the like; other elements of the screen also represent a valuable resource, such as the conductive indium coating. Here, cost- and environmentally-effective recovery techniques will be key. 6 Conclusions There is likely to be only a small market for the remanufacture of flat panel displays, and it will be largely restricted to high value units. Repair may Page 14 of 15

15 be possible for a greater fraction, but the rapidly falling cost of new units acts against this. With these constraints, remanufacturers will have to operate with very low cost bases. Companies in the Social Enterprise area would most likely to able to make this work while commercial companies will find it hard without volume of good condition core. WEEE legislation could be tightened to encourage manufacturers to adopt product design policies that better enable reuse and cannibalisation. Océ in the Netherlands has used this model successful with a part remanufacture process line running next to their factory processing new products. Even if manufacturers are not able to progress to that level, they could use the returns from the field as a source of spares to maintain their products with their customers. It is likely that alternative approaches to remanufacture will be more relevant in this market. The TSB project demonstrating repurposing of old screens to produce single pixel displays is a creative approach to the problem. The issue in this case will be obtaining the volume of used units in a suitable condition for further use. In the short to medium term, the prospect of LED displays may make LCDs a transient phenomenon. LEDs do not contain the rare and hazardous substances of LCDs and are offering high intensities and contrast that could displace plasma. The technology is also compatible with existing silicon-based wafer technologies. Page 15 of 15