METHOD AND DEVICE FOR COMPENSATING NONLINEAR MAGNIFICATION STRAIN IN PROJECTION TELEVISION SYSTEM

摘要

Means and method are disclosed for compensating for non-linear magnification distortion in projection television systems. The projection television system has a projection screen for displaying a light image cast thereon. The screen is spaced apart from at least one light projection means whose projection optical axis lies at a non-zero, acute- angle A with respect to the screen axis. The light projection means comprises cathode ray tube means having a cathodoluminescent screen on the inside surface of a face panel thereof whose axis is substantially parallel to the projection optical axis. Electron- beam generating means are disposed on the cathode ray tube electron-optical axis for forming an electron image on the cathodoluminescent screen which is converted to a visible image by the cathodoluminescent screen. Lens means on the projection optical axis provide for projecting on the projection screen the light image of the electron-formed visible image. The light image inherently has non-linear magnification distortion attributable to the location of the projection means off the projection screen axis.P PThe system is characterized according to one embodiment of the invention by the cathode ray tube electron-optical axis defining a non- zero, acute-angle B with respect to the axis of the cathodoluminescent screen. The value of the angle B and the orientation of the electron optical axis is selected according to the invention to cause the electron- formed visible image to have an orientation and a non-linear magnification distortion effective to substantially compensate for the off-axis-induced non-linear magnification distortion of the projected light image.