| 摘要 |
PURPOSE:To attain the vertical incident electron beams to an image screen, by specifying the magnetic field directions of three deflecting coils to make vertical the electron beams to the image screen. CONSTITUTION:The incident electron beams are deflected by a former phase coil 21, and the resultant electron beams travel almost straightly in a magnetic field generated by an object lens main coil 22 whose magnetic field faces from the image screen to the incident point side, and digest the majority of a specific deflection amount. If only the object lens and the main coil 22 are used, the electron beams travel in the direction a and reach the image screen in a certain inclination. On the other hand, if only a latter phase coil 23 is used, the beams advance in the direction b by the lens and the latter phase coil 23, and reach the screen in another inclination different from that of a. By setting the a and the b in a specific condition, the both inclinations deny each other, and the beams are radiated vertically to the image screen.
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