| 摘要 |
<p>A deflection apparatus comprising a cathode ray tube produces a field gradient that reduces a tendency of a major axis of a beam spot to become elongated at each corner, at each end of a horizontal axis and at each end of a vertical axis of a display screen (22) relative to the beam spot at the center of the display screen. A beam spot stigmator (24) causes the beam spot to be substantially anastigmatic at each of the corners, the end of the horizontal axis and the end of the vertical axis of the display screen. In an embodiment of the invention, means (11) are provided for producing a first non-uniform field providing a lensing action containing a time varying field portion not produced by the deflection coils (10, 99), said means (11) comprising a quadrupole doublet.</p> |
