| 摘要 |
471,103. Cathode-ray tubes. MANIFOLD, M. BOWMAN-. Nov. 27, 1935, No. 32945. [Class 39 (i)] Electromagnetic deflecting coils for a cathode-ray tube are arranged to prevent " pin-cushion " distortion when the radius of curvature of the screen is less than the distance from the screen to the centre of the deflection region ; for this purpose the coils are so arranged that lines of force due to those producing deflection in one direction, are curved towards the centre of the region. Fig. 2 shows an arrangement of coils A, A<1>, B, B<1> for producing deflection in one direction, and coils C, C<1>, D, D<1> for producing deflection at right-angles to the first, arranged with a magnetic yoke Y having projecting poles 1, 2, 3, 4 the lines joining opposite poles being at 45‹ to the direction of deflection. The yoke and poles may be omitted, but the coils should still be arranged so that those producing deflection in one direction should be nearer to each other than to those producing deflection in the direction at right-angles thereto. As the deflection increases more rapidly the greater it is, the currents should increase more slowly as they become greater. |
