A system (93) monitors the break-up phase of an electrostatic deflection continuous ink jet printer to identify phase instability likely to be caused by a partial blockage of the jet-forming device (17). It ignores alternations between adjacent phase positions and brief unrepeated periods of phase disruption. Preferably it ignores phase changes caused by changes in other operational parameters of the printer, such as variations in ink pressure. Monitoring may be done in the printer (99) or in an external system (93), (95).

A method for compensating for failed printing nozzles in an inkjet printing machine uses a computer to provide an increased ink drop volume of adjacent nozzles. All existing printing nozzles are measured regarding print failure and deviation of a printed dot beyond a specific threshold, so that the printing nozzles are marked either as functioning, failed, or printing a dot deviating in a direction transverse to the printing direction, and the results are saved on the computer. The computer hides all functioning printing nozzles and marks all remaining isolated printing nozzles as failed nozzles. The computer groups adjacent remaining printing nozzles by marking nozzles printing a dot deviating in a direction transverse to the printing direction as functioning printing nozzles contributing to the compensation or as failed printing nozzles in accordance with a rule, and the computer compensates for all printing nozzles having been marked as failed.

There is provided a liquid discharge apparatus including: a head having nozzles; a conveyer; and a controller. The controller is configured to carry out a conveyance process of conveying a recording medium in a conveyance direction, and a discharge process of discharging a liquid from the nozzles to the recording medium. The discharge process includes a plurality of discharge steps carried out to a unit area of the recording medium based on data obtained by decomposing an image data into complementary patterns. In at least one of the discharge steps corresponding to the unit area, a function of a discharge duty of the nozzles has an ascending portion or a descending portion. The controller is configured to carry out before the discharge process: a detection process of detecting a defect nozzle in the nozzles; and in a case that the defect nozzle is detected, a change process of changing the function.

A method of operating a printer analyzes a printed test pattern in a low-contrast printing configuration. The method includes forming a printed test pattern having a plurality of rows of negative marks on an image receiving member, each negative mark in the plurality of rows of negative marks being surrounded by ink from at least a portion of the plurality of inkjets. The method further includes generating scanned image data of the test pattern and identifying a plurality of locations in the cross-process direction for the negative marks in at least one row of negative marks in the scanned image data of the test pattern.

Inkjet printing equipment capable of measuring a droplet includes a process stage providing a processing space for a process substrate, a pair of guide members disposed on opposite sides of the process stage, a head unit discharging a droplet onto the process substrate, a first gripper moving along the pair of guide members and gripping a side portion of the process substrate, a second gripper configured to move along the guide members and gripping a measurement substrate onto which a droplet is discharged in order to inspect the head unit, and a droplet inspection unit inspecting a discharge state of the droplet discharged onto the measurement substrate and outputting information of whether the discharge state of the droplet is normal or abnormal.

An information processing system includes a storage portion that stores a learned model obtained by performing machine learning on a maintenance condition for a print head based on a data set in which ink flow path inside information indicating a state of an ink flow path of the print head, nozzle surface image information obtained by photographing a nozzle plate surface of the print head, and maintenance information of the print head are associated with each other, an acquisition portion that acquires the ink flow path inside information and the nozzle surface image information, and a processing portion that outputs the maintenance information based on the acquired ink flow path inside information, the acquired nozzle surface image information, and the learned model.

A three dimensional printer is configured to move at least one printhead from an area where the printhead is forming an object to a position opposite a shaft. The at least one printhead is operated to eject material onto the shaft and the shaft is rotated to enable a light sensor to generate signals indicative of a height of material at a plurality of positions on the shaft. The signals are compared to an expected height of material at each position to identify inoperative inkjets in the at least one printhead.

A liquid discharge apparatus includes a discharge head including a discharge surface formed with a plurality of discharge openings from which a liquid is discharged, a cap configured to be detachably attached to the discharge head and form a holding space for a cleaning liquid such that the cleaning liquid contacts the discharge surface, a supply portion configured to connect to the cap and to supply the cleaning liquid to the holding space, and an outlet portion configured to connect to the cap and to drain the cleaning liquid from the holding space. The supply portion is formed at a position facing the discharge surface. The outlet portion is formed at a position outside the supply portion in an inside-outside direction of the discharge surface.

A printhead maintenance module is configured as a replaceable unit. The module includes a frame, at least two rollers detachably mounted within the frame, at least two electric motors, a platen, an optical sensor, and a controller. Each electric motor is operatively connected to one of the rollers in a one-to-one correspondence. The controller is configured to operate one of the electric motors to rotate one of the rollers to move media from a position opposite a printhead where a test pattern is printed on the media to a position opposite the optical sensor, receive image data of the printed test pattern generated by the optical sensor, and identify inoperative ejectors with reference to the image data of the test pattern.

A maintenance device includes a plurality of heads that discharges liquid for printing. A cleaner selectively cleans the heads. A cleaning controller controls the cleaner. A determiner determines a cleaning time when the cleaner cleans one of the heads. An interruption-resumption controller controls the heads to interrupt printing at the cleaning time and resume printing when the cleaner finishes cleaning the one of the heads. The cleaning controller controls the cleaner to clean the one of the heads whenever the interruption-resumption controller controls the heads to interrupt printing at the cleaning time.