John Baird’s version of mechanical television
The promotional literature distributed by the Farnsworth Television
Corporation in the 1930s described Philo’s invention as electronic television. This was to distinguish Farnsworth’s totally electronic system from mechanical television. For while mechanical television was dependent on large, cumbersome revolving discs, or in some cases, rotating mirrored drums, Farnsworth’s electronic television system had no moving parts.
For a number of years, several inventors had tinkered with mechani-
cal television with only limited success.
In one version of mechanical television, an image was produced by a
neon tube that glowed red with varying intensity through a series of small square perforations in a spiral pattern on a spinning disc. The aluminum discs were about the size of an extra-large pizza and were used for both transmission and reception purposes.
The mechanical television system was problematic, to say the least.
A major difficulty was that the transmitting scanning disc had to be perfectly synchronized with the receiving disc. If the discs were out of sync, the resulting picture would range from extremely blurry to indistinguishable. And even when the discs were perfectly in sync (which wasn’t all that often), the image’s resolution was still very poor—thirty lines compared to Farnsworth’s initial sixty and later four-hundred-plus line image.
The image lines in mechanical television ran vertically (instead of horizontally as in the electronic system) and were slightly curved since they were generated by a large revolving disc.
The low image resolution of John Logie Baird’s mechanical television was a major disadvantage that led to the technology’s replacement by electronic television systems.
Another negative aspect of mechanical television was the size of the
televised image. For example, the 1939 Baird Televisor’s red and black
image was only half the size of a business card.
Mechanical television, in its crudest forms, had been around since
the mid-1880s. The Russian-German scientist Paul Gottlieb Nipkow is
credited with inventing the first mechanical television system in 1884.
Nipkow’s American counterpart, Charles Francis Jenkins, spent several
years improving the mechanical system and gave it the name “Radiovision.”