Abstract: A piezoelectric ink jet printing module has a semiconductive material on a surface of a piezoelectric element of the module.

Abstract: A piezoelectric ink jet printing module has a semiconductive material on a surface of a piezoelectric element of the module.

Abstract: A piezoelectric ink jet printing module has a semiconductive material on a surface of a piezoelectric element of the module.

Abstract: In the embodiments of the simplified ink jet head described in the specification, a carbon body is formed with ink passages, such as internal passages extending through a carbon plate, pressure chambers on one side of a carbon plate, flow-through passages on the other side of the same plate and ink supply passages, and a piezoelectric plate is affixed to the pressure chamber side of the carbon plate by a thin layer of epoxy adhesive. The piezoelectric plate may have a conductive coating on one side which is photo-etched to produce an electrode pattern corresponding to the pattern of the pressure chambers in the carbon plate. An orifice plate may have specially profiled orifice openings to assure axial projection of drops and may be affixed by a thin layer of epoxy adhesive to a carbon plate having orifice passages supplying ink from the pressure chambers to the orifices.

Abstract: In the embodiments of the simplified ink jet head described in the specification, a carbon body is formed with ink passages, such as internal passages extending through a carbon plate, pressure chambers on one side of a carbon plate, flowthrough passages on the other side of the same plate and ink supply passages, and a piezoelectric plate is affixed to the pressure chamber side of the carbon plate by a thin layer of epoxy adhesive. In one alternative embodiment, an ink jet head assembly contains two separate carbon pressure chamber plates, a carbon manifold plate and a carbon collar to retain the carbon plates in an assembly.

Abstract: In the embodiments of the simplified ink jet head described in the specification, a carbon body is formed with ink passages, such as internal passages extending through a carbon plate, pressure chambers on one side of a carbon plate, flowthrough passages on the other side of the same plate and ink supply passages, and a piezoelectric plate is affixed to the pressure chamber side of the carbon plate by a thin layer of epoxy adhesive. The piezoelectric plate may have a conductive coating on one side which is photoetched to produce an electrode pattern corresponding to the pattern of the pressure chambers in the carbon plate. An orifice plate may have specially profiled orifice openings to assure axial projection of drops and may be affixed by a thin layer of epoxy adhesive to a carbon plate having orifice passages supplying ink from the pressure chambers to the orifices.

Abstract: In the ink jet printing system described in the specification, a hot melt ink jet printhead having two ink reservoirs is coupled through an ink supply line to a remote hot melt ink supply and a temperature controller is arranged to control the temperatures of the ink in the remote ink supply, the supply line, the ink reservoirs in the printhead and passages leading from the reservoirs to the ink jet orifices at selected temperature levels to inhibit high-temperature degradation of the ink while permitting the ink to be jetted at the desired jetting temperature. In addition, a pressure control system controls the pressure of the ink in the printhead at one or more selected levels to permit the printhead to be used at different orientations and to permit purging of air bubbles and contaminants from the orifice passageways and to supply a relatively high vacuum to a deaerator in the printhead to extract dissolved air from the ink.

Abstract: A single pass ink jet printer includes a plurality of ink jet modules arranged in adjacent rows extending across the width of the surface of an object which is moved with respect to the printer. The modules are mounted on and joined to a manifold which is mounted in a support frame. Ink is supplied to the manifold through an opening in the frame and the manifold distributes the ink to corresponding openings in the ink jet modules where it is directed to arrays of ink pressure chambers and to an outlet which communicates with a corresponding return passage in the manifold leading back to the ink supply. As a result, ink is circulated continuously through all of the ink jet modules, thereby maintaining pigment in suspension in a pigmented ink. An ink supply is removably connected to the printhead through quick-disconnect couplings and, to prevent contamination of the ink in the printhead, filters are provided in the ink supply and at the inlet to the printhead.

Abstract: In the ink jet head described in the specification, a reservoir body contains three ink reservoirs and a vacuum reservoir and a cover plate at the front of the reservoir body provides passages to supply ink from the ink reservoirs to an ink jet array from which ink is selectively ejected in response to electrical signals. Air-permeable, ink-impermeable membranes in a lung plate adjacent to the cover plate provide one wall of the ink passages, and the opposite sides of the membranes communicate with the vacuum reservoir. The reservoir body is made of a heat-conductive material and is removably received in an insulating housing containing a cartridge heater which supplies heat to the bottom of the reservoir body.

Abstract: In the simplified ink jet head described in the specification, a tubular member made of air-permeable, ink-permeable material which is closed at one end and connected at the other end to a source of subatmospheric pressure is inserted into an ink passage in the ink jet head to extract dissolved air through the material of the tubular member from a surrounding body of ink in the ink passage.

Abstract: In the representative embodiments disclosed in the specification, an ink jet system includes a carriage for driving an ink jet head having a reservoir containing ink in a reciprocating motion and a counter for counting ink drops ejected through orifices in the ink jet head, and a nonvolatile memory for storing a number corresponding to the number of drops ejected and for generating a signal to terminate operation of the head or to produce a warning signal or to permit completion of printing of a sheet being printed when the number in the memory reaches a selected value. The ink jet head, which is removable from the system, has a refillable reservoir and, to prevent unauthorized refilling, a security arrangement utilizing a special code or a fuse is provided.

Abstract: In the embodiments of the simplified ink jet head described in the specification an orifice plate has specially profiled orifice openings to assure axial projection of drops when ink is supplied from an asymmetric ink path leading to the orifice. For this purpose the orifice includes cylindrical ink inlet and outlet portions with the ink outlet portion having a smaller diameter and a shorter length than the inlet portion and a tapered conical portion joining the ink inlet portion and the ink outlet portion. Preferably, the diameter of the inlet portion is no more than about twice the diameter of the outlet portion.

Abstract: In the embodiments described in the specification, a ceramic piezoelectric plate is polarized by compressing the plate between electrode plates with intervening slightly conductive rubber sheets or by applying electric charge from a corona discharge device to one surface of the plate while the opposite surface is grounded until the applied charge is sufficient to create a breakdown.

Abstract: An ink jet head has a reservoir containing hot melt ink and an orifice plate with orifices, along with passages leading from the reservoir to the orifices to conduct ink thereto. The ink jet head includes a heater to melt the ink in the reservoir, along with a further heater to heat air in the airspace above the ink in the reservoir, and the reservoir has a sealable vent which is sealed by a sealing element at a maintenance station so that heating of the air increases the pressure in the reservoir to cause purging, an absorbent member being provided at the maintenance station adjacent to the orifice plate to trap ink ejected during purging.

Abstract: In the embodiments disclosed in the specification, a mounting arrangement for a replaceable ink jet head on a reciprocating carriage includes corresponding mounting pads on a rearwardly-facing surface of the carriage and on a forwardly-facing surface of the ink jet head and resilient electrical contacts on a rearwardly-facing surface of the ink jet head. In one embodiment, a clamp arrangement engages the rearwardly-facing surface of the ink jet head and includes a plurality of electrical contacts for engaging the electrical contacts on the rearwardly-facing surface of the ink jet head.

Abstract: In the ink jet printing system described in the specification, a hot melt ink jet printhead having two ink reservoirs is coupled through an ink supply line to a remote hot melt ink supply and a temperature controller is arranged to control the temperatures of the ink in the remote ink supply, the supply line, the ink reservoirs in the printhead and passages leading from the reservoirs to the ink jet orifices at selected temperature levels to inhibit high-temperature degradation of the ink while permitting the ink to be jetted at the desired jetting temperature. In addition, a pressure control system controls the pressure of the ink in the printhead at one or more selected levels to permit the printhead to be used at different orientations and to permit purging of air bubbles and contaminants from the orifice passageways and to supply a relatively high vacuum to a deaerator in the printhead to extract dissolved air from the ink.

Abstract: In the representative ink supply system described in the specification, continuous circulation of ink in an ink jet head is accomplished by providing two reservoirs connected to each ink jet orifice through corresponding passages so that ink flows continuously from a high-level reservoir past the orifice to a low-level reservoir. The difference between the levels of ink in the reservoirs is maintained relatively constant by inertial pumping during reciprocal motion of the ink jet head or by pressure transfer of ink from one reservoir to the other reservoir. Cross-flow purging of air or debris from the ink jet head is effected by covering the ink jet orifices and applying air pressure to one reservoir to cause ink and any trapped air or debris to flow from the head to the other reservoir. A pump responsive to reciprocal motion of the ink jet head generates a positive air pressure which is applied during purging and a negative air pressure which is applied to a deaerator for removing dissolved air from the ink.

Abstract: In the embodiment of the hot melt ink supply unit described in the specification, a block of solid hot melt ink has a peripheral surface formed with a key configuration and a handle is removably connected to the block by a threaded projection. After insertion of the block into a correspondingly keyed opening in a heated reservoir, the handle is turned to separate the handle portion from the block of solid ink. A container provided with a removable seal encloses the block of solid ink and handle to protect the ink from contamination.

Abstract: In the embodiment of the hot melt ink supply unit described in the specification, a block of solid hot melt ink has a peripheral surface formed with a key configuration and a handle is removably connected to the block by a threaded projection. After insertion of the block into a correspondingly keyed opening in a heated reservoir, the handle is turned to separate the handle portion from the block of solid ink. A container provided with a removable seal encloses the block of solid ink and handle to protect the ink from contamination.

Abstract: In the particular embodiment of a device for removing dissolved gas from ink described in the specification, an elongated ink path leading to an ink jet head is formed between two permeable fluorine-containing membranes. The membranes are backed by air plenums which contain support members to hold the membranes in position. Reduced pressure is applied to the plenums to extract dissolved gas from the ink in the ink path without accumulating scum on the membrane surfaces. Increased pressure can also be applied to the plenums to eject ink from the ink jet head for purging. Within the ink jet head, ink is circulated convectively from the orifice to the deaerating path even when the jet is not jetting ink.