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lundi 19 mai 2014

Basic Overview Of TV Covers

By Minnie Whitley


Television is a box-shaped device that can receive television signals and turn them into moving images on a screen with audio to its speakers. The devices are built in a transparent and photosensitive cathode. Signals are transferred to the transmitter from which they are sent to the recipients. The signals may, among other things, be captured by an antenna, a satellite dish (if there is satellite TV covers), or cables.

Each frame contains 288 lines for a total of 576 lines per full view, hence the term 576i used for comparisons between different television systems. In order to reproduce the surface, it is equipped with red, green and blue dots arranged in groups of three, but with such a relative position that the entire screen is covered. There are then three electron guns in the display tube, one for each color.

If the electrons from the blue cannon hits a blue dot, this action lights up the pixel. If a red, a blue and a green dot are next to each other, it shines with a certain brightness which the eye perceives as white. By mixing the three colors, most colors are rendered. This is called additive color mixing.

In 1872, English telegraph worker Joseph May, discovered that it was possible to convert light into an electrical signal. German engineer Paul Nipkow, later invented the Nipkow disc, where images are read through a spiral of holes. This idea was later on employed by John Logie Baird from the UK and Charles Francis Jenkins from America to build the world's first television.

Another system uses a rotating mirror with multiple pages (four, six, eight and so on) and a number of angled mirrors behind. This system can display at very high resolution images of several hundred lines. In fact, laser printers use a similar system with a versatile rotating mirror.

Analog broadcasting via terrestrial transmitters ceased in some countries and has been transferred to digital transmission. In order to receive a broadcast from a terrestrial transmitter you require a digital TV tuner. There are three different types of analog color television system: PAL, SECAM and NTSC. PAL is used in most of Europe, Africa, China and Australia.

Televisions have mainly been used to entertain, inform and educate. They brought visual news and information to a broad audience, this created some major developments in aspects such as propaganda and mind manipulation, where sublime messages were often used in advertising.

A television or electronic camera is a device that electronically receives motion pictures which are then transmitted directly to a TV receiver or stored on various media such as magnetic tape, DVD or hard drive. A camera is used mainly by professional broadcasters and can be seen as a precursor to the camcorder.




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