I have read that although manufacturing of TV sets came to a complete halt for the war effort, TV research and design continued unabated at RCA & DuMont. The image orthicon tube & camera were developed during the war, and were first demonstrated in 1944. These companies wanted to be ready to roll TV sets off the production lines at the earliest opportunity. DuMont began manufacturing the first postwar set late in 1945, beating RCA to market.