Patent ID: 6452320
Filing Date: 2002-09-17
Classification: H01J

Abstract:
A main lens of an electron gun of a cathode ray tube, the main lens for receiving an electron beam emitted by the electron gun, the lens focusing the electron beam along a focal axes incident to a display surface, comprising:a grid electrode positioned substantially orthogonally with respect to the focal axis, the grid electrode including at least one aperture for focussing the electron beam, the aperture being centered about the focal axis and having a shape expressed by the equation (1): (xa)2n+(yb)2n=1(1)where x and y define respective horizontal and vertical axis locations in the Cartesian coordinate system where 1where a and b define respective horizontal and vertical axis half-widths of the aperture and the exponent n determines a deviance of the aperture from ellipticity, whereby the shape of the at least one aperture diminishes focal aberrations of the lens.