An inkjet printing apparatus includes an ink jetting unit to jet ink to a substrate, a stage to movably support the substrate relative to the ink jetting unit, and a pair of air-conditioning units arranged at front and rear ends of the ink jetting unit in a direction in which the stage is moved, the air-conditioning units each including an air blowing unit and a suction unit.

A drop-on-demand printing method comprising performing the following steps in a printing head: discharging a first primary drop (x21A) of a first liquid to move along a first path; discharging a second primary drop (x21B) of a second liquid to move along a second path; controlling the flight of the first primary drop (x21A) and the second primary drop (x21B) to combine the first primary drop with the second primary drop into a combined drop (x22) at a connection point (x32) within a reaction chamber within the printing head so that a chemical reaction is initiated within a controlled environment of the reaction chamber between the first liquid of the first primary drop and the second liquid of the second primary drop; and controlling the flight of the combined drop (x22) at least by means of a stream of gas (x71A, x71B).

A valve comprises an orifice plate (1) having one or more orifices (4) through which a fluid may flow, and one or more piezo-electric elements (2). Each element (2) has a face positioned to contact the orifice plate at an orifice. Each element has a first state in which it abuts the plate to prevent flow of fluid through the associated orifice and a second state in which the face is spaced from the plate to allow flow through the associated orifice. A controller (50) selectively applies a first voltage to an elements to cause it to adopt the first state and applies a second voltage to the one or more elements to cause the elements to adopt the second state.

A valve comprises an orifice plate (1) having one or more orifices (4) through which a fluid may flow, and one or more piezo-electric elements (2). Each element (2) has a face positioned to contact the orifice plate at an orifice. Each element has a first state in which it abuts the plate to prevent flow of fluid through the associated orifice and a second state in which the face is spaced from the plate to allow flow through the associated orifice. A controller (50) selectively applies a first voltage to an elements to cause it to adopt the first state and applies a second voltage to the one or more elements to cause the elements to adopt the second state.

The jetting frequency of droplets of printing fluid from a nozzle of an electrohydrodynamic printer is increased by 50% or more over previous e-jet printers. The charging electrode is strategically arranged to locate layers of material in the gap between the electrode and an extraction surface to provide a breakdown voltage in the gap that is higher than that of air. By locating a tip of the charging electrode inside the ink nozzle, non-conductive printing fluid in the nozzle and/or a non-conductive nozzle wall can provide dielectric strength in the gap that is relatively high, thereby increasing the maximum voltage of the extraction field. The printer offers other advantages, even when there are no high breakdown voltage materials in the gap between the electrode and extraction surface.

The invention relates to a print head of a binary continuous jet printer comprising: means for producing a plurality of ink jets in a cavity, delimited by lateral walls, and by an upper wall and a lower wall, means for separating drops or sections of one or more of said jets intended for printing from drops or sections that do not serve for printing, a slot, which passes through the lower wall, enabling the exit of ink drops intended for printing, a gutter for recovering drops or sections not intended for printing, means for injecting gas into the cavity, and for making this gas circulate, in the cavity, to the means for producing a plurality of ink jets in said cavity, then to the gutter.

A valve comprises an orifice plate (1) having one or more orifices (4) through which a fluid may flow, and one or more piezo-electric elements (2). Each element (2) has a face positioned to contact the orifice plate at an orifice. Each element has a first state in which it abuts the plate to prevent flow of fluid through the associated orifice and a second state in which the face is spaced from the plate to allow flow through the associated orifice. A controller (50) selectively applies a first voltage to an elements to cause it to adopt the first state and applies a second voltage to the one or more elements to cause the elements to adopt the second state.

An electrohydrodynamic printer has a self-cleaning extractor that can cleaning itself during printing. The extractor can be in the form of a metal block or a metal rod along which a layer of cleaning fluid flows from a source of cleaning fluid to a collector. The surface of the extractor along which the cleaning fluid flows can be adjustable between horizontal and any other angle. The self-cleaning extractor eliminates the need to interrupt e-jet printing cycles to clean stray printing fluid from the extractor by continuously keeping the extractor clean during ink extraction and printing.