| 摘要 |
The electromagnetic screen can be of steel with a relative permeability much greater than 1, and extends past the picture screen towards the operator to an extent approx. equal to the distance between the top and bottom sides of the electromagnetic screen. Its wall thickness is less than 1 mm. Alternatively the electromagnetic screen can be of a material with a relative permeability approx. equal to 1 and a low resistance, e.g. copper or aluminium. Another form involves screens or cores with high relative permeability being positioned outside the picture tube deflection coils, and comprising iron powder or other material moulded in synthetic pulp so that electrical insulation between the powder granules is obtained. |
