CATHODE-RAY TUBE

Japanese Patent JPH05198275

A

PURPOSE: To lessen the interference effect by defining the window inside face as z=f(x, y) wherein x, y stand for coordinates obtained by dividing the long and the short axes X, Y by two and keeping a point coming off the axes in a specified relation in a CRT having a curved rectangular display window having the long and the short axes. CONSTITUTION: In the case the inside face of a display window is defined as z=f(x, y) in a coordinates system, the extent of the increase in Z direction at a point which comes off the coordinates can be calculated from secondary degree partial derivatives of respective standard coordinates; zxx =σ<2> z/σx<2> , zyy =σ<2> z/σy<2> , zxy =σ<2> z/(σxσy). In this case, if x>0, y>0, or x<0, y<0 sinxy=+1 and if x>0, y<0 or x<0, y>0, sinx =-1 and -(zxx zyy )<1/2>