An input pen assembly is provided which selectively cooperates with the screen of a cathode ray tube of a CRT display and the tablet of a tablet input device. The assembly automatically activates either one of the CRT display and the tablet input device in response to a change in the magnitude of a pressure...http://www.google.fr/patents/US4263592?utm_source=gb-gplus-shareBrevet US4263592 - Input pen assembly
