偏转对电子束上屏束径的影响

Research of Deflection Defocusing in Electron Optical System

彩色显像管中，电子束经偏转系统偏转后在屏的边角处的尺寸比中心部分尺寸大。为了解决偏转散焦，日本松下公司推出了ＤＡＦ枪。然而随着ＨＤＴＶ的发展，电子束束流和偏转角都越来越大，此时仅靠调节动态聚焦电压不能完全补偿过聚焦以及大束流下空间电荷效应的影响。本文研究了大束流、大偏转角情况下造成偏转散焦的原因，提出在调节动态聚焦电压的同时适当改变电子束进入主聚焦透镜的入射角，从而改善电子束经偏转后的上屏质量。

The spot size at the edge of color picture screen is larger than the size that at the center. To copy with this problem, some experts proposed the dynamic astigmatism and focus (DAF)gun. However,the size of electron beam deflected to the edge of screen with large current still increases because of the effects of space charge and over-focus. This paper studies the reasons influencing deflection defocusing, and proposes a new way to improve the quality of electron beam deflected to the edge of screen. In the new method, incident angle varies with the deflection angle, so radius of deflected beam can be decreased while space charge effects and over-focus are taken account in. It is shown the size of deflected beam decreased 15% by the new method.