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History
Main article: History of television
Television was not invented by a single person, but by several individuals and
one of them was John Logie Baird (JL Baird). The origins of what would become
today's television system can be traced back to the discovery of the
photoconductivity of the element selenium by Willoughby Smith in 1873, followed
by the work on the telectroscope and the invention of the scanning disk by Paul
Nipkow in 1884. All practical television systems use the fundamental idea of
scanning an image to produce a time series signal representation. That
representation is then transmitted to a device to reverse the scanning process.
The final device, the television (or TV set), relies on the human eye to
integrate the result into a coherent image.
A transistor-based portable television, typical of NTSC models of the late 1960s
and 1970sElectromechanical techniques were developed from the 1900s into the
1920s, progressing from the transmission of still photographs, to live still
duotone images, to moving duotone or silhouette images, with each step
increasing the sensitivity and speed of the scanning photoelectric cell. John
Logie Baird gave the world's first public demonstration of a working television
system that transmitted live moving images with tone graduation (grayscale) on
26 January 1926 at his laboratory in London, and built a complete experimental
broadcast system around his technology. Baird further demonstrated the world's
first color television transmission on 3 July 1928. Other prominent developers
of mechanical television included Charles Francis Jenkins, who demonstrated a
primitive television system in 1923, Frank Conrad who demonstrated a
movie-film-to-television converter at Westinghouse in 1928, and Frank Gray and
Herbert E. Ives at Bell Labs who demonstrated wired long-distance television in
1927 and two-way television in 1930. Camarena invented the "Chromoscopic adapter
for television equipment", an early color television transmission system. As it
is written in the patent: The invention relates to the transmission and
reception of colored pictures or images by wire or wireless. Even though the
invention was not already adaptable to standard television equipment then in
use; the invention was considered easy to adapt to any transmitter or receiver
of black and white television equipment. He applied for this patent the August
14, 1941 and obtained the patents for color television systems the September 15,
1942 (U.S. Patent 2296019), 1960 and 1962.
Color television systems were invented and patented even before black-and-white
television was working; see History of television for details.
Completely electronic television systems relied on the inventions of Philo
Taylor Farnsworth, Vladimir Zworykin and others to produce a system suitable for
mass distribution of television programming. Farnsworth gave the world's first
public demonstration of an all-electronic television system at the Franklin
Institute in Philadelphia on 25 August 1934. All modern television systems
derive directly from Farnsworth's model.
Regular broadcast programming occurred in the United States, the United Kingdom,
Germany, France, and the Soviet Union before World War II. The first regular
electronic television broadcasts began in Germany in 1935, using first an
electronic system with 180 lines, followed in 1937 with an improved system with
441 lines. The first regular public (i.e. not cable) television broadcasts with
a modern level of definition (240 or more lines) were made in England in 1936
from Alexandra Palace. Baird's mechanical 240-line system alternated with
EMI-Marconi's so-called "System A" with 405 lines; as this proved far more
reliable, Baird's system was dropped after four months. Regular network
broadcasting began in the United States in 1946, and television became common in
American homes by the middle 1950s. While North American over-the-air
broadcasting was originally free of direct marginal cost to the consumer (i.e.,
cost in excess of acquisition and upkeep of the hardware) and broadcasters were
compensated primarily by receipt of advertising revenue, increasingly United
States television consumers obtain their programming by subscription to cable
television systems or direct-to-home satellite transmissions. In the United
Kingdom, France, and most of the rest of Europe, on the other hand, operators of
television equipment must pay an annual license fee, which is usually used to
fund (wholely or partly) the appropriate national public service broadcaster/s
(e.g. British Broadcasting Corporation, France Télévisions, etc.).
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