The Flat Screen has been the standard television and computer monitor display since the early Caroline Era. Introduced by Sinclair in the form of a battery powered pocket television in 1983, the following year saw a larger "wall screen" model which could be hung on a wall like a picture, and the year after, quadruple versions were introduced which were able to display HDTV pictures. This provided a big boost to the newly introduced high definition versions of the television channels in countries which used the 1250-line system such as the British Isles, Low Countries and Germany, and was particularly important for the HD-only channels BBC3 and the OBA channel. Before their invention, high-definition television sets were either very large or projection sets, which in either case were very expensive and therefore unpopular.
The original flat screen television had a bent cathode ray tube with an electron gun projecting to one side. A transparent electrostatically-charged plate is used to reflect the beam at right angles to its original path, enabling sets to be made thinner than the older design of CRT. The wall screen version consists of four tubes joined together with the electron guns projecting above and below the screens, doubling the resolution in both dimensions. The smaller, single-gun form is still used for computer displays. In the second decade of the Caroline Era, additional innovations enabled the tubes to be made flatter.
Without the introduction of wall screens, HDTV would probably not have taken off. Because they were much cheaper than the larger sets used before, many more people bought them and they frequently became the main type of television, though the lower resolution flat screens were still used in portable sets. Another influential factor, which took a while to filter through, was that the aspect ratio was 16:9 rather than 4:3, so programmes began to be produced in wide screen and films could be seen and broadcast without using pan-and-scan or the letterbox format. Portable and pocket televisions also used the 16:9 ratio but still used the older system.
Microcomputers use lower resolution flat screen display systems, built into the case rather than separately. This necessitates certain form factors because of the electron gun projecting from one side of the screen. This is normally accommodated in the case containing the system board, which is often U-shaped so that the tube can be slotted into place "inside" the computer without adding to the thickness. This is used in laptops particularly, though these also have LEDs. Microcomputer displays are green and black, and are also used to view electronic newspapers and as videophones. However, microcomputers can also be connected to wall screens. EReaders also use flat CRTs.
Rival display technologies
Where space or power consumption is at a premium, LEDs are used instead. For a short period, LCDs were used, but suffer from their small viewing angle and size and lack of intrinsic illumination. They are also quite fragile and can't display colour.