DEVICE FOR RATIONALIZING IMAGE PICKUP TUBE BEAM FOCUS

• Main Authors: KATASE WATARU, NAKAGAKI SHINTARO, ICHIMURA HIROSHI, KITAMI KAORU, NEGISHI ICHIRO, OSADA MASARU, TAKANASHI RYOYU
• Format: Patent
• Language: English
• Published: 10.08.1989
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PICTORIAL COMMUNICATION, e.g. TELEVISION

PURPOSE:To constantly attain a rational focus by changing the focus electric pole voltage of a pickup tube by only a prescribed quantity corresponding to the generation period of a signal for a signal level detection and controlling the focus electric pole voltage in the direction of the enlargement of the level of an output signal. CONSTITUTION:A pattern for a signal generation for a signal level detection with prescribed repeated patterns is formed in the pickup tube PT and the focus electric pole voltage of the pickup tube PT is changed to a positive and a negative by a prescribed quantity against an initial value corresponding to the generation period of a signal for a signal level detection generated at specific intervals on a time axis. A first signal and a second signal to indicate the level of a pickup tube output signal are generated, when the first signal is greater than the second signal, the focus electric pole voltage is increased by a focus signal generation circuit FCSG, when the second signal is greater than the first signal, the focus electric pole voltage is decreased. Thus, the condition of a beam focus is constantly auto-controlled at an optimum condition.