How Does a Television Work

just as a radio and a telephone are devices for converting acoustic energy into electrical and vice versa, the television receives wirelessly transmitted electromagnetic waves and converts them into acoustic and light energy for viewing. Although the initial inspiration for the television existed as early as the 1830s, when inventor Michael Faraday demonstrated the relationship between light and electricity, the television did not become practical for mass-production until more than a century later - in the 1940s. The history of the television is marked by a series of devices that were progressively more effective at sending or receiving wireless electronic patterns containing light and sound information.

The first "televisions", like the first computers, made use of mechanical media to store information. In 1883, German engineer Paul Nipkow introduced a device using a rotating scanning disk that was perforated with small holes in a spiral pattern. Images could be "broken down" through the use of a sensitize photocell placed behind the spinning disk. The photocell then transmitted the image as a series of electrical impulses to a receiver, where the electricity could again be converted into light and shined through an identical spinning disk, which reconstituted the initial image - but at a very poor level of resolution. Many variants and imitations of this mechanical TV system were invented and used by hobbyists and electronics enthusiasts throughout the next quarter-century. Incremental improvements occurred, but the mechanical television primarily remained a curiosity impractical for mass use.

The modern television was only made possible with the scientific advances of the early 1900s, which included significant developments in radio, x-rays, and physics. Wireless transmission of sound became possible with the invention of the radio at the turn of the century. But the critical component necessary for the high-fidelity projection of reconstituted light information was the cathode-ray tube, originally used to produce x-rays for medical purposes. In 1906, Karl Braun found that manipulating the electron stream of the cathode-ray tube with a magnetic field was possible. Less than a year later, it was suggested that the cathode-ray tube be used as a receiving device for images. Russian scientist Boris Rosing quickly created such a cathode-ray tube and encouraged further development of the technology.

Rosing's student, Vladimir K. Zworykin, migrated to the United States after WWI and created the "iconoscope", a device that scanned an image with an electron beam and converted it into electronic signals for transmission. To minimize the amount of data needing to be sent, he fed the image through a "mosaic" - a plate covered with microscopic photosensitive dots we now know as "pixels". The information was then broadcasted and received by a device that ran the process in reverse, using the cathode-ray tube to project images far more quickly and effectively than the mechanical televisions of the past. The first incarnation of the modern TV was born. It was successfully demonstrated in a public context in 1929.

The next two decades saw a series of advances that made TV easy and practical. Televisions did not begin to enter the family home until the late 40s and early 50s. NBC of New York was the first broadcaster to utilize the new technology. Technological improvements in 1945 resulted in the familiar black-and-white television. Color television arrived in 1953. Basic television technology has not changed substantially until recently, with the introduction of HDTV (High Definition Television). Today the average American watches between two and six hours of television per day.