How Television Works?

From the moment first inventors came to conclusion that electrons can transfer data and audio, they quickly started forming ideas about system that would be able to record, transmit, receive and reproduce video images over large distances. For that purposes, many inventors of late 19th and early 20th century invested significant efforts, finally managing to create early prototypes of modern analogue television systems. With steady advances in technology and polarization of many types of television devices, television standards soon managed to put firm control over television space, enabling cheap and reliable sets to find their way into the homes of families in Europe and North America.

In its basic concept, analogue television represents transmission of analog broadcast data that holds in itself encoded audio and video signal that can be reproduced on a television set, with all appropriate brightness and color points of the image and sound waves of the original signal (or simply put, transferring electromagnetic waves into sound and light energy).

This type of concept was first introduced in mechanical television system that was held back by significant deficiencies in their picture quality. Pioneered by the German technician and inventor Paul Gottlieb Nipkow, mechanical television managed to remain in the center of television invention between 1880s and 1920s after it was replaced by fully electrical systems. This system used spinning disc with series of holes in spiral pattern that scanned the environment in front of it and recorded photons using photoelectric cell. On the reproduction end, picture was created with similar spinning disc that projected the scanlines that were created by modulated light source, usually neon tube. Mechanical television systems received steady stream of upgrades during the decades after initial introduction by Nipkow, most notably by Charles Francis Jenkins in 1920s and early 1930s in United States and John Logie Baird in England.

However, even with all the advances of mechanical television it still remained held back by slow refresh rates (which caused very noticeable flickering) and low resolution. The solution to those problems came with fully electrical television systems that used cathode-ray tube (CRT) to convert received data into precisely steered electrons that “wrote” image in vertical lines across surface coated with phosphor. Because this effect can be very fast and accurate, and phosphorus is an element that retains much of it light even after electron beam is no longer hitting it, television systems that used CRT could produce stable and consistent image with scan lines that are closely packed together, enabling creation of high resolution images.

Because of this clearly superior technology, CRT television systems became instantly popular all across the world, especially because they were relative clear to make and significantly easier to maintain than mechanical televisions. After more than 70 years, analogue television signals finally started being replaced with digital transmissions and newer display technologies (LCD, Plasma, OLED) in early years of 21st century, with the plans for majority of the world to adopt this advanced transmission and reproduction method before 2020.