A recording element substrate includes a substrate, a plurality of energy generating elements arranged on the substrate to form an element row, a plurality of supply ports arranged along the element row to form a supply port row, and a plurality of supply paths extending from the plurality of supply ports along the thickness direction of the substrate, wherein a plurality of beam portions disposed between adjacent supply ports in the direction of the supply port row has a plurality of conductor layers in which a conductor layer including a power supply conductor connected to the energy generating elements and a conductor layer including a ground conductor connected to the energy generating elements, are stacked along the thickness direction of the substrate, and wherein at least one of the plurality of conductor layers is occupied by one power supply conductor or one ground conductor.

A device (20) for measuring the flow rate and the viscosity of ink sent to a print head (50) of an ink jet printer, comprising: a conduit (200), for supplying the print head (50), this conduit being provided with a 1.sup.st pressure (Pin) sensor (26) at a first end and a 2.sup.nd pressure (PHead) sensor (56) at a 2.sup.nd end, circuit or controller (26, 56) for measuring at least the pressure (PHead) of the 2.sup.nd pressure sensor (56) and the pressure difference (Pin−PHead) between the 1.sup.st pressure sensor (26) and the 2.sup.nd pressure sensor (56).

A device (20) for measuring the flow rate of ink sent to a print head of an ink jet printer, comprising: a restriction (22) of the diameter of the flow of ink, arranged in the path thereof, sensors (26, 28) for measuring the pressure difference (P.sub.in−P.sub.out), between the pressure of fluid upstream of the restriction (P.sub.in) and the pressure of ink downstream of the restriction (P.sub.out).

A print head of a continuous ink jet printer comprising: a cavity for the circulation of jets, delimited laterally by a 1.sup.st side wall and a 2.sup.nd side wall, both at least partially parallel to a direction of flow of the jets in the cavity, at least one nozzle for producing at least one ink jet in the cavity, at least one electrode for sorting drops or segments of one or several of the jets intended for printing from drops or segments that are not used for printing; an outlet slot, open onto the exterior of the cavity and allowing the exiting of the drops or segment of ink intended for printing, at least one gutter for recovering drops or segments not intended for printing, at least one spraying nozzle, arranged in the cavity, for projecting at least one cleaning fluid towards at least one inner portion of the cavity and a motor driving the at least one spraying nozzle in rotation about an axis (x), for example perpendicular to a direction of flow of the jets in the cavity; a supply circuit supplying at least the spraying nozzle with cleaning fluid.

According to some examples a substance displacement apparatus may comprise a gas ejection aperture and a deflector arm. The gas ejection aperture may be to direct gas towards a roller having a surface on which a substance is disposed. The deflector arm may be moveable between a first position in which gas is directed away from a target area on the surface of the roller, and a second position in which gas is directed towards the target area on the surface of the roller, thereby to displace at least some of the substance from the surface of the roller within the target area. A method and a print apparatus are also disclosed.

A method for operating a printhead of a continuous inkjet printer comprising: producing at least one ink jet in a cavity of the print head; electrostatically separating drops or sections of one or more of the jet intended for printing from drops or sections that do not serve for printing; exiting from the cavity drops or sections of ink intended for printing, through a slot open on the outside of the cavity; and circulating at least one flow of air along the outlet slot of the cavity in a direction essentially perpendicular to at least one jet of ink emitted by the printhead and intended for printing. The air having a water vapor pressure lower than the water vapor pressure defined by 100% relative humidity at the coldest temperature of the printer.

A method for operating a printhead of a continuous inkjet printer comprising: producing at least one ink jet in a cavity of the print head; electrostatically separating drops or sections of one or more of the jet intended for printing from drops or sections that do not serve for printing; exiting from the cavity drops or sections of ink intended for printing, through a slot open on the outside of the cavity; and circulating at least one flow of air along the outlet slot of the cavity in a direction essentially perpendicular to at least one jet of ink emitted by the printhead and intended for printing. The air having a water vapor pressure lower than the water vapor pressure defined by 100% relative humidity at the coldest temperature of the printer.

A method is provided for cleaning a print head, wherein the print head includes a cavity for the circulation of jets and at least one first spraying nozzle for projecting at least one cleaning fluid towards at least one inner portion of the cavity. The method includes the step of projecting, using the first spraying nozzle, several pulses of cleaning fluid towards the inside of the cavity.

A method is provided for cleaning a print head, wherein the print head includes a cavity for the circulation of jets and at least one first spraying nozzle for projecting at least one cleaning fluid towards at least one inner portion of the cavity. The method includes the step of projecting, using the first spraying nozzle, several pulses of cleaning fluid towards the inside of the cavity.

Systems and methods for industrial printing, e.g., using drop-on-demand (DOD) inkjet print heads, include, in at least one aspect, a printing device including: a print head including a print engine, including multiple nozzles, and circuitry to selectively eject ink through the multiple nozzles to form an image on a moving substrate, and to purge the ink through the multiple nozzles; and a printhead enclosure having an opening in front of the multiple nozzles to allow the selectively ejected ink to pass through the opening when the selectively ejected ink is ejected toward the moving substrate; wherein the printhead enclosure includes a hole placed away from the multiple nozzles; and wherein the printhead enclosure is configured to direct the ink that is purged through the multiple nozzles along an inside surface of the printhead enclosure to the hole through which the ink flows and exits the printhead enclosure.