Electron gun for colour cathode ray tube - compensates focusing strength of electron beam due to change in strength of main focusing lens using first dynamic quadrupole pre-focussing lens.

摘要

The electron gun includes a cathode (11a), a control electrode (12a) and a screen electrode (13a), which form a triode. First, second, third and fourth focusing electrodes (14a,15a,16a,17a) form two pre-focusing lenses. An end accelerating electrode (18a) forms a main focusing lens (300a). The pre-focusing lenses are synchronous with the deflection signal and the first includes a first and a second focusing lens (100a). The strength of the focusing of an electron beam is compensated after the influence of the change in the strength of the main focusing lens. ADVANTAGE - Light beam spot of good quality is formed over entire screen.