| 摘要 |
PURPOSE:To obtain a wider deflection area without increasing DAC resolving power by a method wherein, when the deflection data of the deflecting pole which is not present on the X-axis and Y-axis is divided into the amount of data proportionate to each deflection pole, the dividing data is increased 1/a(a>1) times, it is increased b(b>1, for example) times after D/A conversion so that it is brought within the limit of resolving power of a digital-analog convertion (DAC), and it is applied to the deflection electrode. CONSTITUTION:The eight deflecting poles 81-88 of a scanning deflector 8 are concentrically arranged leaving equal intervals with the optical axis of an electron beam as the center point, and they are formed completely in the same shape. When the deflection data xc and xy are given, the data of-(xd+yd)/2, -yd, (xd-yd)/2, xd, (xd+yd)/2, yd, -(xd-yd)/2, and -xd are D/A-converted on a DAC 11 for deflection through a deflection data dividing circuit 12 and a multiplying device 13. They are increased 2-1/2 times by an amplifier 14, and the voltage corresponding to -(xd+yd)/2<1-2>, -yd, (xd-yd)/2<1-2>, xd, (xd+yd)/2<1-2>, yd, -(xd-yd)/2<1-2>, -xd is applied to the deflecting pole 8.
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