Lighttable screen for 55 inch tv driver#

In 1937, both Philips and HMV put on display at the Radiolympia show in London, television sets that had a screen size of 25 inches based on the same MS11 Philips/Mullard tube. The early white phosphors were not as efficient as later offerings and these early televisions had to be watched in subdued lighting. The accelerating voltage used for these tubes was very low by later standards and even a twelve inch tube only ran from a 5000 volt supply. This necessitated a tube that was relatively long for its screen size. However, because the tube face had to be convex to provide resistance to air pressure, this mitigated the problem but only if the apparent deflection centre was more or less at the centre of curvature of the screen. The ability to correct the deflection signals for aberrations in tube geometry had not yet been developed, and it was necessary to make tubes that were relatively long compared with their screen size to minimise distortion.

Lighttable screen for 55 inch tv driver#

The principal driver for the British government's move was to establish cathode ray tube production facilities which it believed would be vital if the anticipated World War 2 was to materialise. In 1936, the British government persuaded the British Broadcasting Corporation to launch a public high definition (for the era ) television broadcasting service. Twelve inch tubes could be manufactured, but these were so long that they had to be mounted vertically and viewed via an angled mirror in the top of the cabinet. The largest practical tube that could be made that was capable of being mounted horizontally in a television cabinet of acceptable depth was around nine inches. Since the tube had to contain a very high vacuum, the glass was under considerable stress, together with the low deflection angle of CRTs of the era, the practical size of CRTs without increasing their depth was limited.

It relied on conventional glass blowing methods largely unchanged in centuries. Background and History Necessity Ĭathode ray tube technology was very limited in the early days of television.