| 摘要 |
PURPOSE:To make it possible to realize the driving function with one D/A convertor by allocating sample and hold circuit to respective deflection electrode, thereby employing the D/A convertor with time division. CONSTITUTION:Drive amplifiers 2a to 2h and sample and hold circuits 3a to 3h are allocated to respective deflection electrodes of an octopole electrostatic deflector 1, and the deta per respective deflection electrodes are selected by a data-selector under the control of a multiplex control logic to be converted into an analog by a D/A convertor 4, and then sampled and holded in the sample and hold circuit in response to the data pass. Said operations are successively performed in respective deflection electrodes, to supply a voltage to respective deflection electrodes of the octpole deflector 1. Therefore, it is possible to independently supply an arbitrary voltage to eight piecies of the deflection electrodes by one D/A convertor. With this constitution, since the voltage is supplied to all of the deflection electrodes by one D/A convertor, the gains of D/A conversion by respective channels are completed.
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