Cathode-ray tubes and valves for television receivers

The paper surveys the progress made in the design and manufacture of valves and cathode-ray tubes for television since the medium was first discovered. The survey is divided into three parts corresponding to three distinct stages in the development of valves, namely the pre-war period, the war-time standstill and the years since the war. In the earliest days most television valves were merely variations on existing types, but development of special valves soon began and was hastened by the adoption of our present transmitting system in 1937. Meanwhile, tube design had also progressed and 10¿12-in magnetically focused tubes were used in 1937. During the war little work was done on television tubes and valves. Service demands speeded the production of miniature and all-glass valves, but cathode-ray-tube technique benefited only indirectly from war-time experience and a fresh start was necessary in 1945. The duty of the valve industry at this time was to help to make television receivers reliable, efficient and cheap. Some methods of performing this task are discussed and the consequent demands on valve designers considered. New types of valve and tube are described in some detail. Turning from development to production, the paper describes advances in the mechanization of valve production which have led to the attainment of production speeds rivalling those of any other country. Mass-production methods have also been introduced into tube manufacture since the end of the war, and an account of current methods closes the third part of the paper. After a statistical survey of valve and tube production between 1935 and 1951 has been given, views on future trends in both production and design are put forward. It is concluded that the valve industry is in a healthy condition now and that there is reason for optimism about its future.