| 摘要 |
PURPOSE:To suppress positive trilemma in a picture area when used in combination with a frame aberration correcting coil by connecting in parallel a pair of raster distortion correcting coils with each of which a single diode is connected in series in such a manner that their respective diodes are facing in opposite directions. CONSTITUTION:A vertical deflection current flows through an upper coil 6 only when a specific voltage + V0 or over is retained. Thus, when this voltage level is not retained, no pin-cushion type magnetic field is generated by the coil 6, causing only the barrel distortion of diametrical magnetic field to be weakened with the resulting reduced positive trilemma (intersection of R and B beams) in the upper half of a picture area 1. Also, a vertical deflection current flows through a lower coil 8 only when a diode connected in opposite direction stays ON i.e., -V0 or less is retained, causing positive trilemma to be reduced in the lower half of the area I. With voltage level being +V0 or over, an element 5 is activated and a pin-cushion magnetic field is produced, making it possible to correct pin-cushion distortion in the upper portion of the raster and negative trilemma in an upper picture area II. With voltage level being -V0 or less, an element 7 is activated for correction in a similar manner. The continuity time for the coils 6, 7 is established through selecting of characteristics of the elements 6, 7, series count, and value of a resistance 9. |
