Allwebco Web Templates · Build your own toolbar · Accept Credit Cards · Audio, Fonts, Clipart
powered by
bravenet.com
|
|
Electronic
television
|
An American family watching television in the 1950s.Although the discoveries of Nipkow, Rosing, Baird and others were extraordinary, little of their technology is used in modern television. By 1934, all electromechanical television systems were outmoded, although electromechanical broadcasts continued on some stations until 1939.
A.A. Campbell-Swinton wrote a letter to Nature on the 18 June 1908 describing his concept of electronic television using the cathode ray tube, which had been invented in 1897 by the German physicist and Nobel prize winner Karl Ferdinand Braun. He proposed using an electron beam in both the camera and the receiver, which could be steered electronically to produce moving pictures. He lectured on the subject in 1911 and displayed circuit diagrams, but no one, including Swinton, knew how to realize the design. Although his system was never built, the cathode ray tube did come to be used to display images in almost all television sets and computer monitors until the invention of the LCD panel.
A fully electronic system was first achieved by Philo Taylor Farnsworth on September 7, 1927, although the low-resolution, light-insensitive camera tube limited the image to a plate of glass painted black, with a straight line etched across it, rotated in front of a bright carbon arc lamp. Seven years later, on August 25, 1934, at the Franklin Institute in Philadelphia, Farnsworth gave the world's first public demonstration of a working, all-electronic television system, with 220 lines per picture, 30 pictures per second. Over a three week period, vaudeville acts, athletic and sports demonstrations, politicians, and hundreds of ordinary citizens were captured on Farnsworth's cameras in the open air and simultaneously shown on his receiving sets.
Farnsworth, a Mormon farm boy from Rigby, Idaho, first envisioned his system at age 14. He discussed the idea with his high school chemistry teacher, who could think of no reason why it would not work (Farnsworth would later credit this teacher, Justin Tolman, as providing key insights into his invention). He continued to pursue the idea at Brigham Young Academy (now Brigham Young University). At age 21, he demonstrated a working system at his own laboratory in San Francisco. His breakthrough freed television from reliance on spinning discs and other mechanical parts. All modern picture tube televisions descend directly from his design.
Vladimir Kosma Zworykin is also sometimes cited as the father of electronic television because of his invention of the iconoscope in 1923 and his invention of the kinescope in 1929. His design was one of the first to demonstrate a television system with all the features of modern picture tubes. His previous work with Rosing on electromechanical television gave him key insights into how to produce such a system, but his (and RCA's) claim to being its original inventor was largely invalidated by three facts: a) Zworykin's 1923 patent presented an incomplete design, incapable of working in its given form (it was not until 1933 that Zworykin achieved a working implementation), b) the 1923 patent application was not granted until 1938, and not until it had been seriously revised, and c) courts eventually found that RCA was in violation of the television design patented by Philo Taylor Farnsworth, whose lab Zworykin had visited while working on his designs for RCA.
The controversy over whether it was first Farnsworth or Zworykin who invented modern television is still hotly debated today. Some of this debate stems from the fact that while Farnsworth appears to have gotten there first as an inventor, RCA brought television sets to market before Farnsworth, and it was RCA employees who first wrote the history of television. Even though Farnsworth eventually won the legal battle over this issue, he was never able to fully capitalize financially on his invention.
Home Page1 Page2
Page3 Page4 Page5
motorcycle sun glasses
bravenet.com