Ionographic printhead gating control for controlling charge density image defects due to surface velocity variations

Claim 1

In an ionographic imaging device, including a source of ions, means for moving ions in a stream towards a moving imaging surface to create a pattern of charge thereon, modulation means to modulate the stream of ions in imagewise fashion to form intelligible charge patterns on the imaging surface, and means for controlling an amount of charge deposited at any given position on the imaging surface, independent of movement of the imaging surface, comprising: means for detecting incremental motion of the imaging surface, and producing a signal indicative thereof; a gating electrode supported adjacent a path of the stream of ions; a voltage source, connected to said gating electrode, and operating between two conditions to drive said gating electrode to produce either a field allowing passage of the stream of ions past the gating electrode, or a field blocking passage of the stream of ions past the gating electrode by varying a magnitude of the field; means for controlling said voltage source responsive to said incremental motion detecting means, to produce a field allowing passage of the stream of ions past said gating electrode for a predetermined time after receipt of said signal; current sensing means, supported adjacent the path of the stream of ions, downstream from said gating electrode, for sensing an amount of ion flow; feedback means for altering operation of said voltage source controlling means, in accordance with the amount of ion flow past said current sensing means.