Cathod ray tubes in Televisions

 

William crock and J.J Thomsan discovered electron in 1875. Instrument used in this experiment called Cathod rays tube are gas discharge tube 

it is made up of glass tube. It has two metallic electrodes connected to a source of high voltage electrode connected to negative terminal of battery is called cathode and that connected to positive terminal of battery is called anode flourocent screen is fitted to recorded flourosence or glow. A vacuum pump is connected to tube which decrease pressure inside the tube which allows gas to polarizes when high voltage applied gas inside the tube start ionizing glow produced inside the tube travel from anode towards Cathode these rays are called cathode rays and tube is called cathode tube, latter on during studying properties of these rays scientist realize that these are very small particles instead of rays and these particles named elecron.

These type of Cathod ray tube (CRT) with slightly modifications used in television computer and computer monitor screens.

Televisions working principle are based on CRT

Basic working principle in Televisions are cathode ray tube.

The cathode ray tube (CRT) in a TV is a glass vacuum tube. The inner surface of the screen is coated with tiny phosphor dots that emit light in the three primary colors (red, green, and blue). These phosphor dots glow when struck by an electron beam, resulting in the images we see on screen. The electron beam is a focused stream of electrons pouring off an electrode to which negative voltage is being supplied.

The electrons emitted from the so-called electron gun strike the phosphor dots, causing them to glow. Deflection coils that create magnetic fields are used to enable the electron beam to strike any phosphor dot on the screen.

In LCD and LED TVs instead of Cathod ray tube produce images by using liquid crystals to either transmit or block light.

Differences between LCD and LED TVs are back lighting only basic principle is based on liquid crystal system in both LCDs and LEDs, but in Televisions basic working principle is based on the Cathode ray tube.

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