The inventive concept provides an inkjet printing method. The inkjet printing method for discharging an ink on a substrate using a head having a plurality of nozzles formed thereon includes determining a grade of nozzles by measuring a discharge performance of the nozzles, which is a grading step; selecting a use nozzle that can participate in printing the substrate among the nozzles based on the grade determined at the grading step, which is a nozzle selecting step; and discharging the ink on the substrate using at least one nozzle among use nozzles, which is a printing step.

A liquid ejection apparatus includes a liquid ejection head having a nozzle face in which a plurality of nozzles is opened, the plurality of nozzles ejecting liquid as a droplet, a cleaning unit configured to clean the nozzle face, an information receiving unit configured to receive input of a cleaning information that is information related to a frequency of cleaning of the nozzle face by the cleaning unit, and a controller configured to instruct the cleaning unit to perform the cleaning in accordance with the cleaning information.

A liquid discharging apparatus includes: a first storage which stores liquid; a first detector which detects an amount of the liquid in the first storage; a communication hole communicating the first storage and outside; a semipermeable membrane arranged to cover the communication hole; a head unit having at least one nozzle which discharges the liquid supplied from the first storage; a liquid flow channel which communicates the first storage and the head unit; a cap which seals the nozzle of the head unit; a cap movement mechanism which moves the cap; an electrode arranged in the cap and on which the liquid discharged from the nozzle is landed; a second detector connected electrically to the electrode; a suction mechanism which sucks the liquid and gas inside the cap; a waste liquid storage which stores the liquid sucked from inside of the cap by the suction mechanism; and a controller.

A cap device includes a cap, an accommodation member, and a cover. The cap covers a nozzle surface of a liquid ejection head. The accommodation member is accommodated in the cap and is fixed to the cap. The accommodation member has a conductivity and receives a voltage that generates a potential difference between the liquid ejection head and the accommodation member. The accommodation member includes a first portion and a second portion connected with each other. The cover covers the second portion of the accommodation member, and has a surface that is co-planar with a surface of the first portion. The cover has a conductivity and receives a voltage that generates a potential difference between the liquid ejection head and the cover.

A liquid ejection head has a nozzle. A controller is configured to: control the liquid ejection head to perform inspection driving, the inspection driving being driving the liquid ejection head to eject liquid from the nozzle for determining whether the nozzle is an abnormal nozzle having an abnormality in ejection of liquid; acquire a determination signal outputted from the signal output device, the determination signal indicating whether the nozzle is the abnormal nozzle; acquire a non-driving signal outputted from the signal output device when the inspection driving is not performed by the liquid ejection head; generate a differential signal by superposing the determination signal and the non-driving signal, the differential signal being a signal indicating a difference between a value of the determination signal and a value of the non-driving signal at each timing; and determine whether the nozzle is the abnormal nozzle based on the differential signal.

A determination signal indicates whether each of a plurality of nozzles of a liquid ejection head is an abnormal nozzle. A controller stores, in a memory, information on a nozzle determined to be the abnormal nozzle among the plurality of nozzles; in response to receiving a particular signal and determining that the memory does not store abnormality flag information and that the number of the abnormal nozzle stored in the memory is larger than a first threshold value, control a recovery device to perform a recovery operation; and in response to receiving the particular signal and determining that the memory stores the abnormality flag information and that the number of the abnormal nozzle is larger than a second threshold value, control the recovery device to perform the recovery operation. The second threshold value is smaller than the first threshold value.

A printing apparatus includes a printing head that includes a plurality of nozzles, each of which ejects an ink pushed out from a pressure chamber by driving of an actuator, a display unit, a detector that generates a residual vibration in the pressure chamber by imparting, to the actuator, a predetermined drive signal that prevents the nozzle from ejecting the ink, and, based on the residual vibration, performs, for each of the plurality of nozzles, defective nozzle detection processing of detecting a defective nozzle having ejection failure, and a display control unit that causes the display unit to display defective nozzle information including a position, in the printing head, of the defective nozzle detected by the detector.

There is provided a liquid discharge apparatus including: a liquid discharge head having a nozzle; an electrode facing the nozzle; a power supply which generates a potential difference between the liquid discharge head and the electrode; a first output unit which outputs a first signal in accordance with an electric change in a case that the liquid discharge head is caused to perform inspection driving; a low-pass filter; a second output unit; a high-pass filter; a third output unit; and a controller. The controller executes determination as to whether or not the liquid is normally discharged from the nozzle, based on the first signal; and determination as to whether or not a short circuit occurs between the liquid discharge head and the electrode, based on a second signal output from the second output unit and a third signal output from the third output unit.

A failure time estimation device includes: a memory configured to store a machine-learned model obtained by performing machine learning using teaching data associating printer information including at least one of operation history of a printer, state information indicating a current state, and a print result image indicating a print result with failure time of the printer; and a controller configured to obtain the printer information and estimate the failure time of the printer using the obtained printer information and the machine-learned model.

To enable highly accurate density unevenness correction while suppressing a reduction in productivity in printing accompanying correction value calculation for density unevenness correction. Based on an image obtained by scanning a chart including patches having uniform density for each tone value, a density characteristic of each nozzle is acquired. A non-ejectable nozzle that cannot eject ink normally is detected by analyzing a pattern for detecting the non-ejectable nozzle in the image obtained by scanning the chart. At the time of acquiring the density characteristic, the density characteristic is acquired based on a density measured value of an area of the image, which corresponds to a nozzle that is not detected as the non-ejectable nozzle.