Mechanical Television

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History

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Advertisement for Radiovision.
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Early Radiovision

In June of 1923 Charles Jenkins, an inventor from Dayton, Ohio, invented and transmitted the earliest moving images through a mechanical television system called Radiovision. He publicly performed his first transmission, from Anacosta, Virginia to Washington, D.C. in June of 1925. Jenkins Laboratories constructed a Radiovision transmitter, W3XK, in Washington D.C. The short-wave station began transmitting radiomovies across the Eastern U.S. on a regular basis by July 2, 1928. As far back as 1894, Jenkins had been promoting mechanical television when he published an article in the "Electrical Engineer” describing a method of electrically transmitting pictures. In 1920, at a meeting of the Society of Motion Picture Engineers, Jenkins introduced his prismatic rings, a device that replaced the shutter on a film projector and an important invention that Charles Jenkins would later use in his Radiovision system.

How It Works

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The transmitter had to be set in a studio in total darkness. Holes would be punched in a spiral disc would allow only light to be passed through these selective regions. The spinning disk would emit light bounced off of the subjects face from a light source within the transmitter onto a photoelectric cell that would convert the light image into electric signals. These would, in turn, be amplified and sent via radio waves to a receiver on the other end.

The receiver on the other end would convert these electric impulses into a sequence of bright flashes in a neon tube located within the receiver. A disc would rotate very rapidly in front of this tube and converted every small flash into a part of the overall image. The speed of the disc would make “persistence of vision” (when the brain retains an image for one tenth of a second after the eye perceives it) possible for the viewer. Originally the image was very scratchy and the picture had to be constantly adjusted. This made some technical knowledge a necessity thus shrinking the prospective demographic to a select few (mostly men) who knew how to operate these machines. There was also originally no audio to accompany the pictures. Sepreate radios had to be purchased, or used if the viewer already had one, and tuned into a seperate station that would supplement the noises and music for the show they were watching.

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Programming

Despite the limitations that the early, crude mechanical televisions presented, producers began to experiment with storytelling and programming. In 1928, the first television drama was produced. “The Queen’s Messenger”, shot on three cameras, was received on a General Electric Octagon set in Shenectady, New York. The play had two characters, with only the heads or the hands of the four actors visible at any one time. Two actors spoke the lines, while the other two acted as hand models. In 1931 The Radio Corporation of America (RCA) broadcast signals from The Empire State Building featuring the first television star, Felix The Cat.

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Images like these would be broadcast as the first programming attempting to tell a story


Demise

The main problem with the mechanical television was that there was no set standard for production of the actual sets as well as transmission and reception of signals. This being the case, signal strength ws always very weak and the unit itself required constant tuning to keep the picture relatively clear. The invention of the glass vacuum tube television both expanded the audience demographic because it required little to no picture fine tuning and made the mechanical television obsolete.

Works Cited

  • Jenkins, Charles F. Animated Pictures. New York: Arno P, 1898.
  • Jenkins, Charles F. Vision by Radio, Radio, Photographs, Radio Phonograms. Washington, D.C.: National Capital P, 1925.
  • N/A. "New Color Television". Science Newsletter, 1948.
  • Monfort, Ray A. A Brief History of Television for the Layman. Los Angeles: University of California P, 1949.
  • Reily, John W., and Frank V. Cantwell. Some Observations on the Social Effects of Television. Oxford UP, 1949.
  • All pictures taken from www.televisionexperimenters.com