Print head element, print head and ionographic printing apparatus

An ionographic printing apparatus comprising the following elements:

• A) an ionographic imaging station comprising a print head 313 facing an electrostatic charge receiving member comprising an electrically insulating layer for receiving at one side thereof a latent electrostatic charge image, said electrically insulating layer being present in an electric field for attracting ions onto said side, said print head comprising print head elements having:
• 1) a means for introducing an ionisable gas or gas mixture into a channel of each print head element,
• 2) a driver electrode,
• 3) a control electrode,
• 4) a dielectric body keeping said driver electrode and control electrode separate,
• 5) means for applying an alternating voltage between said driver electrode and control electrode, said voltage being effective for the ionization of said gas or gas mixture in said channel in an ion generation region between said driver electrode and control electrode,
• 6) a modulation electrode being separate from said control electrode by dielectric material,
• 7) means for applying a direct current voltage between said modulation electrode and control electrode to either block said ions in said channel or to allow the flow of said ions out from said channel,
• B) a development station for developing said charge image by means of toner particles so as to obtain a visible toner image,
• C) a transfer zone wherein said toner image can be transferred onto an intermediate toner image receiving member or directly onto a final substrate, and
• D) a cleaning station for removing residual toner particles, and
• E) a station for removing residual electrostatic charges, and
• F) a fixing station for fixing said transferred toner image onto said final substrate wherein:
• (i) said channel is a tubular channel having at one end, at the side of the driver electrode, an inlet opening for receiving said ionisable gas or gas mixture,
• (ii) said driver electrode is a planar electrode surrounding said tubular channel,
• (iii) said driver electrode is embedded in dielectric material of said dielectric body, whereas said control electrode has a border area defining part of said tubular channel so as to make contact with said ionisable gas or gas mixture, and
• (iv) said modulation electrode at the other end of said tubular channel 201 has an aperture allowing said flow out of ions from said tubular channel.

A method for placing an electrostatic charge pattern resulting from pattern-wise projection of ions onto a dielectric substrate comprising the steps of:

• A) introducing into a channel of print head elements part of an ionographic print head an ionisable gas or gas mixture,
• B) producing said ions in said channels by an alternating voltage applied between a driver electrode and a neighbouring control electrode, both said electrodes being separated by a dielectric body,
• C) modulating a stream of ions by either blocking or allowing said ions to leave said channels using a modulation electrode at the output side of said channels,
• D) electrostatically attracting ions that are allowed to leave said channels towards said dielectric substrate,
• wherein:
• (i) said ionisable gas or gas mixture is introduced into a tubular channel of each of 5 said print head elements,
• (ii) an alternating voltage being effective for the ionization of said gas or gas mixture is applied between said driver electrode and control electrode, the driver electrode surrounding tubular channel and being embedded in said dielectric body, the control electrode having a border area defining part of 1 o tubular channel for contact with said ionisable gas or gas mixture, and
• (iii) said ions are accelerated out of said tubular channel through an aperture of its modulation electrode by means of a direct current voltage between said modulation electrode and an electrode backing said dielectric substrate.