| 摘要 |
Apparatus, associated with a cathode ray tube (CRT), containing both an electrostatic focusing lens (110) and a magnetic focusing lens (118) for maintaining the focus of an electron beam, within the CRT at any location on a CRT screen. The apparatus applies a dynamic focusing voltage (120) to an electrostatic focus grid of an electron gun and applies a dynamic focusing current (136) to a magnetic focus coil. The focusing voltage and current vary in accordance with the position of the electron beam on the screen. As such, the electron beam remains focused upon the screen for all beam positions.
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