Television
As Television or Television set (originally also Remote clay/tone cinema or that Telehor the television becomes colloquially often also as Flicker crate designated.
The rendition of the pictures takes place usually on one Screen. The use of Projectors as television is uncommon, but possible. Also with its Monitor can by means of one TV map as televisions function. The rendition of the tones become Loudspeaker used, which can lie also outside of the actual equipment.
One differentiates Colour television set, the pictures in to represent can and Black-and-white television, which can represent only gray tone pictures. The latters have today only little meaning, can transmissions in color however likewise evaluate and to their abilities represent accordingly.
World-wide have themselves for that similar Television various different with different Picture resolution established, which are named single letters from A to N; in addition still the three different come Ink transferStandards , and NTSC. In the German-speaking countries the television standards become B for for the moment VHFTransmitter and G for UHFTransmitter as well as the PAL standard for the ink transfer use; in summary one speaks of PAL B/G. With Digital television these standard differences are not except the picture resolution any longer of importance.
With the so-called 100-Hz-Fernsehern becomes that 1. Half-image each picture stored, and then only with that 2. Half-image together represented; afterwards both are again repeated, during already the 1. Half-image of the next picture is received. In the final result each picture is thus shown twice, thus flickering is reduced substantially. With fast moved pictures however a quite aufwaendige digital rework of the pictures is in the equipment necessary (so-called Deinterlacing), over Artifacts to avoid by the in such a way changed timing of the image representation; of favorable 100-Hz-Geraeten this is often not carried out.
The television is served nowadays almost exclusively over IRRemote maintenance. With a frequently existing Hotel mode can certain adjustment possibilities be blocked.
Television types
The following screen types are used as televisions:
- Cathode ray tube screen (Tube television)
- Liquid crystal screen (LCD television)
- Plasma panel
- Back projection terminal
- Video projector
So far television became so mentioned under the term Tube television understood, whereby itself the term Tube on the main construction unit, those Cathode ray tube refers. This is also often called Braun tube (after its inventor of that Cathode (a gluehwendel similarly as in conventional bulbs) extracted at the back of the television by means of high voltage and to in front lying the far Anode to be accelerated.
The high voltage at the anode becomes by a so-called Zeilentrafo produced and amounts to depending upon sceen size 20.000 to 30.000 . This tension can be very easily deadly and continues to exist also after switching off still several-day-long, why work requires special caution on the inside from tube televisions also from otherwise experienced electrical amateur handicraftsmen.
The anode has a hole, by which the electrons can travel through. They become by the magnetic fields of the vertical and horizontal Deflection coils a certain pixel then there diverted and meet a fluorescent layer on the back that Ground-glass plate, whereby it to a flash comes; depending upon the quantity of electrons precipitates this more brightly or more darkly.
Normally the electron beam is driven line by line from left to the right and above downward over the screen and results in in such a way from the different brightness the picture. The repeating rate of a complete procedure (z.B. the screen layout) becomes in (cycles per second) indicated (100 cycles per second = 100 times per second).
With color television sets there are three easily against each other transferred cathodes for the three Basic colours Red, green and blue; one Mask in form of a fine metal lattice scarcely behind the ground-glass plate it ensures in this case for the fact that the electrons of each cathode can meet only points of fluorescence of "their" color. The remaining electrons remain hanging in the mask. The fluorescent layer consists in this case of small points next to one another of the three basic colours, how one can recognize easily, if one near-goes close to the screen.
These conventional televisions are replaced today increasingly from flat picture televisions, which essentially on that PanelTechniques LCD and Plasma are based. Accordingly one speaks of a LCD television or a plasma television.
These new flat picture televisions have disadvantages in principle opposite the tube television. So
- none leaves itself more comparable to the used television picture with them Schwarzwert represent, therefore only a dark grey is possible, instead of genuine black
- is that Color area (number of representable colors) limited, the result is Blaesse of the picture,
- are it shown with fast movements every now and then Nachzieheffekte or Movement artifacts,
- if plasma televisions use very much river, can flicker and age faster than other televisions,
- a usually easy is, with back projection televisions a usually strong dependence of the picture impression with LCD televisions (Brightness, Contrast, for highly soluble television, which is not yet common so far only in Europe. HDTV able Tube television there are in Germany (April 2004) from JVC and Samsung, over further future models at present exists rumors. With Sharp already the first manufacturer stopped the production of tube televisions. Other one, z. B. Panasonic, tube televisions made their model pallet smaller within the product range substantially. Other manufacturers such as Samsung and Philips, develop however new, flatter picture tubes, in order to relate the largest advantage of flat screens at least something.
The image quality and the correct picture adjustment of televisions leave themselves by Test patterns judge.
See also
Web on the left of
- pictures, videos or audio files - Yearly work physics - television engineering
- From the unit receiver to the bag colour television set: Television and colour television set from the initial at the beginning of the television
- Evaluation and purchase criteria for (tubes -) Television
- Reparaturtipps for televisions
