 The earliest version of the CRT was known as the "Braun tube", invented by the German physicist Ferdinand Braun in 1897.It was a cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen.The first cathode-ray tube to use a hot cathode was developed by John Bertrand Johnson (who gave his name to the term Johnson noise) and Harry Weiner Weinhart of Western Electric, and became a commercial product in 1922.