ASTIGMATIC ELECTION LENS, CATHODE-RAY TUBE HAVING SUCH A LENS, AND DEVICE HAVING SUCH A CATHODE-RAY TUBE

摘要

PHN. 8463 An electron lens having a controllable astigmatism and cathode-ray tube having such a lens. The electrode configuration is such that when the lens strength varies in one main direction the lens strength in the other main direction remains unvaried. This is accomplished with extra electrode means influencing the electric field in the gap between the electrodes of the lens, the electric field in the gap being inherently asymmetrical. Application of such a lens in particular in a colour television display tube having three beams in one plane in which the influence of the parastigmatic, self-converging deflection coil system on the focusing of the electron beams is compensated for.