TOP PAGE > P5 Television: The Long-Held Dream

The Long-Held Dream

1875  Carey develops a television that transmits signals over parallel circuits
1876 Bell invents the telephone (patent for telephone transmitter granted)
1877 Edison invents the phonograph
1877 Sawyer develops a television that transmits signals over single wire
1884 Invention of Nipkow disk
1888 Hertz proves the existence of electromagnetic waves
1895 Lumière brothers popularize cinematography
1895 Edison enters the motion picture business
1895 Marconi conducts successful wireless communications experiment
1897 Braun invents Braun tube
1898 Tokyo-Osaka long-distance telephone service begins

In the 20th Century, television, a long-held dream of humankind, became a reality. The advent of TV spurned a new, information-rich environment that revealed the interconnectedness of the world, and brought people across the globe closer together. The impetus was humankind's desire for "Tele-Vision" (to see from afar), an enduring dream from ancient times. Researchers in the technological fields were able to fulfill this dream.

1843 Image Transmission Via Division/Scanning

In the Predawn of the Century of the Moving Image

The latter half of the 19th century saw a new media boom similar in scope and significance to the one occurring now. Pioneers in all the scientific fields dedicated themselves to realizing humankind's dreams.

One important discovery related to basic television imaging technology was the discovery of selenium in 1817. Selenium's photoelectric properties, discovered in 1873 by Willoughby Smith and Joseph May of Great Britain, laid the foundation for the development of television.

Image Scanning, Division, and Reproduction

In the area of image transmission, the most significant development was image division/scanning, which "makes it possible to reconstruct an image that has been divided/scanned for transmission as a signal". The concept of scanning was advanced by Great Britain's Alexander Bain in 1843, and is considered to be the first in television technology. However, Bain's concept of scanning applied to still picture transmission only, and was incapable of transmitting moving images. Present-day television systems transmit what appear to be moving images by sending successive still images of a scene, with each image transmitted within the persistence of th previous image. For example, in a movie, the images are shown at a rate of 24 still pictures (or frames) per second. At this rate, the visual area of the brain interprets successive still images as continuous movement.

The Basis for Current TV System

Knowing the theory and principles involved does not necessarily make it easier to develop - or even to popularize - a practical model.

It was G.R. Carey of the United States, in 1875, who first proposed a television system that utilized the photoelectric phenomenon. This system used multiple photoelectric transducers (which convert light into electricity) and luminous devices (which convert electricity into light) in the display, connecting these in pairs (parallel connection).

In 1877, W.E. Sawyer of Great Britain proposed a system called a serial TV system, which transmits the individual pixel signals of an image in sequence at high speed, instead of transmitting all the pixel signals from a camera at once. The pixel signals transmitted to a receiver via a single transmission line are then reconstructed by reversing the procedure. This idea was the basis for principles used in present-day TV systems.

In 1884, Bain's scanning concept was realized mechanically using the "Nipkow disk", developed by Paul Nipkow of Germany. In 1925, John Logie Baird of Great Britain constructed a mechanical television. However, this system was limited in its image resolution.

On the side of receiver technology, Karl Ferdinand Braun of Germany invented the Braun tube (cathode-ray tube) in 1897. Louis and Auguste Lumière of France developed "cinematography" in 1895, combining a camera, cineprojector, and developing machine. Around the same time, Edison and others in the United States began to see the potential in this new medium, leading to the birth of the motion picture industry.

It was not until the 20th century that these methods of film recording and reproduction developed into the capture and transmission of images by electricity.