Ion current control head

An ion current control head for controlling ion current flying from an ion generation source to provide a pattern of charges on a dielectric medium through openings is arranged in a two-dimensional matrix array in a main scanning direction and a sub-scanning direction intersecting the main scanning direction, comprising:

• (a) first electrically insulating means;
• (b) first electrode means having a plurality of band-like segment electrodes arranged, as a parallel array, on a first plane along a first direction, and supported by the first electrically insulating means;
• (c) second electrode means having a plurality of band-like segment electrodes arranged, as a parallel array, on, a second plane spaced from the first electrode means in a direction to or from which the ion current flies, the band-like segment electrodes being arranged along a second direction different from the first direction and supported by the first, electrically insulating means;
• (d) second electrically insulating means;
• (e) a third electrode means having an undivided continuous electrode separated by the second, electrically insulating means from the, first and second electrode means in the direction to or from which the ion current flies, the third electrode being located on the ion generation source side as viewed from the first and second electrodes so that it faces the ion generation source;
• (f) ion current passage means having openings, each of the openings being located at those intersections of the segment electrodes in the first electrode means and the segment electrodes in the second electrode means, the openings piercing the first, second and third electrode means and being arranged as a two-dimension matrix relative to the main scanning direction and sub-scanning direction;
• and
• (g) control means for applying a first signal voltage across the third electrode means and one of the adjacent electrode means to control whether the ion current is flowed into the opening or suppressed relative to that opening and applying a second signal voltage across the segment electrode selected by the first electrode means and the segment electrode selected by the second electrode means to control whether ion current trapped in a corresponding opening is allowed to be passed or suppressed and for performing a matrix drive operation by the signal voltage applied to the respective electrode so that the ion current can be controlled.