A thin film transistor liquid crystal display (TFT-LCD) is a variant of liquid crystal display (LCD) which uses thin film transistor (TFT) technology to improve image quality. TFT LCD is one type of active matrix LCD, though it is usually synonymous with LCD. It is used in televisions, flat panel displays and projectors.

Small liquid crystal displays as used in calculators and other devices have direct driven image elements – a voltage can be applied across one segment without interfering with other segments of the display. This is impractical for a large display with a large number of picture elements (pixels), since it would require millions of connections - top and bottom connections for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns which reduce the connection count from millions to thousands. If all the pixels in one row are driven with a positive voltage and all the pixels in one column are driven with a negative voltage, then the pixel at the intersection has the largest applied voltage and is switched. The problem with this solution is that all the pixels in the same column see a fraction of the applied voltage as do all the pixels in the same row, so although they are not switched completely, they do tend to darken. The solution to the problem is to supply each pixel with its own transistor switch which allows each pixel to be individually controlled. The low leakage current of the transistor prevents the voltage applied to the pixel from leaking away between refreshes to the display image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout of a TFT-LCD is very similar to that of a DRAM memory. However, rather than fabricating the transistors from silicon formed into a crystalline wafer, they are made from a thin film of silicon deposited on a glass panel. Transistors take up only a small fraction of the area of each pixel; the rest of the silicon film is etched away to allow light to pass through.

The silicon layer for TFT-LCDs is typically deposited using the PECVD process from a silane gas precursor to produce an amorphous silicon film. Polycrystalline silicon (frequently LTPS, low-temperature poly-Si) is sometimes used in displays requiring higher TFT performance. Examples include high-resolution displays, high-frequency displays or displays where performing some data processing on the display itself is desirable. Amorphous silicon-based TFTs have the lowest performance, polycrystalline silicon TFTs have higher performance (notably mobility), and single-crystal silicon transistors are the best performers.

The Airbus A380 is a double-deck, wide-body, four-engine airliner manufactured by the European corporation Airbus, an EADS subsidiary. The largest passenger airliner in the world, the A380 made its maiden flight on 27 April 2005 from Toulouse, France,[3] and made its first commercial flight on 25 October 2007 from Singapore to Sydney with Singapore Airlines. The aircraft was known as the Airbus A3XX during much of its development phase, but the nickname Superjumbo has since become associated with it.

The A380's upper deck extends along the entire length of the fuselage. This allows for a cabin with 50% more floor space than the next-largest airliner, the Boeing 747-400,[4] and provides seating for 525 people in standard three-class configuration[5][6] or up to 853 people in all economy class configuration.[7] The A380 is offered in passenger and freighter versions. The A380-800, the passenger model, is the largest passenger airliner in the world, but has a shorter fuselage than the Airbus A340-600 which is Airbus' next biggest passenger aeroplane. The A380-800F, the freighter model, is offered as one of the largest freight aircraft, with a listed payload capacity exceeded only by the Antonov An-225.[8] The A380-800 has a design range of 15,200 kilometres (8,200 nmi), sufficient to fly from New York to Hong Kong for example, and a cruising speed of Mach 0.85 (about 900 km/h or 560 mph at cruise altitude)

Development

Background

Airbus started the development of a very large airliner (termed Megaliner by Airbus in the early development stages) in the early 1990s, both to complete its own range of products and to break the dominance that Boeing had enjoyed in this market segment since the early 1970s with its 747. McDonnell Douglas pursued a similar strategy with its ultimately unsuccessful MD-12 design. As each manufacturer looked to build a successor to the 747, they knew there was room for only one new aircraft to be profitable in the 600 to 800 seat market segment. Each knew the risk of splitting such a niche market, as had been demonstrated by the simultaneous debut of the Lockheed L-1011 and the McDonnell Douglas DC-10: both planes met the market’s needs, but the market could profitably sustain only one model, eventually resulting in Lockheed's departure from the civil airliner business. In January 1993, Boeing and several companies in the Airbus consortium started a joint feasibility study of an aircraft known as the Very Large Commercial Transport (VLCT), aiming to form a partnership to share the limited market.

In June 1994, Airbus began developing its own very large airliner, designated the A3XX. Airbus considered several designs, including an odd side-by-side combination of two fuselages from the A340, which was Airbus’s largest jet at the time.[9] The A3XX was pitted against the VLCT study and Boeing’s own New Large Aircraft successor to the 747, which evolved into the 747X, a stretched version of the 747 with the fore body "hump" extended rearwards to accommodate more passengers. The joint VLCT effort ended in July 1996, and Boeing suspended the 747X program in January 1997. From 1997 to 2000, as the East Asian financial crisis darkened the market outlook, Airbus refined its design, targeting a 15 to 20 percent reduction in operating costs over the existing Boeing 747-400. The A3XX design converged on a double-decker layout that provided more passenger volume than a traditional single-deck design.

Design phase

On 19 December 2000, the supervisory board of newly restructured Airbus voted to launch a €8.8 billion program to build the A3XX, re-christened as the A380, with 55 orders from six launch customers. The A380 designation was a break from previous Airbus families, which had progressed sequentially from A300 to A340. It was chosen because the number 8 resembles the double-deck cross section, and is a lucky number in some Asian countries where the aircraft was being marketed.[9] The aircraft’s final configuration was frozen in early 2001, and manufacturing of the first A380 wing box component started on 23 January 2002. The development cost of the A380 had grown to €11 billion when the first aircraft was completed.

Boeing, meanwhile, resurrected the 747X programme several times before finally launching the 747-8 Intercontinental in November 2005 (with entry into service planned for 2009). Boeing chose to develop a derivative for the 400 to 500 seat market, instead of matching the A380's capacity.

Production

Major structural sections of the A380 are built in France, Germany, Spain, and the United Kingdom. Due to their size, they are brought to the assembly hall in Toulouse in France by surface transportation, rather than by the A300-600ST Beluga aircraft used for other Airbus models. Components of the A380 are provided by suppliers from around the world; the five largest contributors, by value, are Rolls-Royce, SAFRAN, United Technologies, General Electric, and Goodrich.[10]

The front and rear sections of the fuselage are loaded on an Airbus Roll-on/roll-off (RORO) ship, Ville de Bordeaux, in Hamburg in northern Germany, from where they are shipped to the United Kingdom.[11] The wings, which are manufactured at Filton in Bristol and Broughton in North Wales, are transported by barge to Mostyn docks, where the ship adds them to its cargo. In Saint-Nazaire in western France, the ship trades the fuselage sections from Hamburg for larger, assembled sections, some of which include the nose. The ship unloads in Bordeaux. Afterwards, the ship picks up the belly and tail sections by Construcciones Aeronáuticas SA in Cádiz in southern Spain, and delivers them to Bordeaux. From there, the A380 parts are transported by barge to Langon, and by oversize road convoys to the assembly hall in Toulouse.[12] New wider roads, canal systems and barges were developed to deliver the A380 parts. After assembly, the aircraft are flown to Hamburg, XFW to be furnished and painted. It takes 3,600 litres (950 gallons) of paint to cover the 3,100 m² (33,000 ft²) exterior of an A380.

Airbus sized the production facilities and supply chain for a production rate of four A380s per month.[11]

Testing

Five A380s were built for testing and demonstration purposes.[13]

The first A380, serial number MSN001 and registration F-WWOW, was unveiled at a ceremony in Toulouse on 18 January 2005. Its maiden flight took place at 8:29 UTC (10:29 a.m. local time) 27 April 2005. This plane, equipped with Trent 900 engines, flew from Toulouse Blagnac International Airport with a flight crew of six headed by chief test pilot Jacques Rosay. After successfully landing three hours and 54 minutes later, Rosay said flying the A380 had been “like handling a bicycle” .[14]

On 1 December 2005 the A380 achieved its maximum design speed of Mach 0.96 (versus normal cruising speed of Mach 0.85), in a shallow dive, completing the opening of the flight envelope.[13]

On 10 January 2006 the A380 made its first transatlantic flight to Medellín in Colombia, to test engine performance at a high altitude airport. It arrived in North America on 6 February, landing in Iqaluit, Nunavut in Canada for cold-weather testing.[15]

On 14 February 2006, during the destructive wing strength certification test on MSN5000, the test wing of the A380 failed at 145% of the limit load, short of the required 150% to meet the certification. Airbus announced modifications adding 30 kg to the wing to provide the required strength.[16]

On 26 March 2006 the A380 underwent evacuation certification in Hamburg in Germany. With 8 of the 16 exits blocked, 853 passengers and 20 crew left the aircraft in 78 seconds, less than the 90 seconds required by certification standards.[17]

Three days later, the A380 received European Aviation Safety Agency (EASA) and United States Federal Aviation Administration (FAA) approval to carry up to 853 passengers.[18]

The maiden flight of the first A380 using GP7200 engines - serial number MSN009 and registration F-WWEA - took place on 25 August 2006.

On 4 September 2006 the first full passenger-carrying flight test took place.[19] The aircraft flew from Toulouse with 474 Airbus employees on board, in the first of a series of flights to test passenger facilities and comfort.

In November 2006, a further series of route proving flights took place to demonstrate the aircraft's performance for 150 flight hours under typical airline operating conditions.

Airbus obtained type certificate for the A380-841 and A380-842 model from the EASA and FAA on 12 December 2006 in a joint ceremony at the company's French headquarters.[20][21] The A380-861 model obtained the type certificate 14 December 2007.[21]

As of February 2008, the five A380s in the test programme had logged over 4,565 hours during 1,364 flights, including route proving and demonstration flights.