| 摘要 |
PURPOSE:To match the axes accurately in short time by providing means for producing two-dimensional scanning signal and means for producing sawtooth wave of longer period to be lapped over the exciting current of electron lens for focusing the electron flux. CONSTITUTION:Two-dimensional scanning signal overlapping means 19 will produce sawtooth wave which is lapped over X and Y direction tilt control signals 161, 162. Means 20 for overlapping sawtooth wave having long period will produce sawtooth wave (having plural frames in single period) which is lapped over the output signal from electron leans control signal generator 18 for focusing the electron flux. Consequently, two-dimensional scanning signal is lapped over any one of the shift control or tilt control while at the sametime, a sawtooth signal having different period is lapped over the electron lens thus to adjust the elements where two-dimensional scanning signal is not overlapped while functioning two elements which will vibrate periodically. |
