Herein is described a method involving a drop detector. The method may comprise: ejecting ink drops from the nozzles on a printhead toward a drop detector. A drop characteristic may then be determined from the drop detector for each ink-jet nozzle. Drop characteristics for the nozzles across the printhead may be collated into a data set, and compared with a predetermined data set for a printhead having predetermined print behaviour to determine if and how the data sets differ in terms of the pattern of drop characteristics across the printheads. If the data sets differ, a recovery strategy may be selected based how the data sets differ in terms of the pattern of drop characteristics across the printheads. A system and computer readable medium are also described herein.

Herein is described a method involving a drop detector. The method may comprise: ejecting ink drops from the nozzles on a printhead toward a drop detector. A drop characteristic may then be determined from the drop detector for each ink-jet nozzle. Drop characteristics for the nozzles across the printhead may be collated into a data set, and compared with a predetermined data set for a printhead having predetermined print behaviour to determine if and how the data sets differ in terms of the pattern of drop characteristics across the printheads. If the data sets differ, a recovery strategy may be selected based how the data sets differ in terms of the pattern of drop characteristics across the printheads. A system and computer readable medium are also described herein.

A print head for an inkjet printer includes a nozzle, a first electrode positioned to receive an ink droplet from the nozzle, a second electrode positioned to receive the ink droplet from the first electrode, and a controller configured to operate the first electrode to ionize the ink droplet and set a flight speed of the ink droplet. The controller is further configured to selectively activate the second electrode to deflect the ink droplet in response to the print head changing from a horizontal printing orientation to a vertical printing orientation.

Density of each pixel is specified from a test pattern for measurement of density distribution, a density profile indicating distribution of the specified density for each pixel is acquired, and a pixel region including a nozzle of interest having a certain density difference or more from surrounding pixels and pixels on both sides thereof is extracted as a nozzle region of interest from the acquired density profile. Filters B to E, other than a filter A to be applied for density smoothing processing of pixels that do not belong to the nozzle region of interest, are applied for the density smoothing processing of the pixels in the nozzle region of interest, to generate a profile of a density correction value for eliminating a density difference between respective pixels based on the density profile after the smoothing processing.

Density of each pixel is specified from a test pattern for measurement of density distribution, a density profile indicating distribution of the specified density for each pixel is acquired, and a pixel region including a nozzle of interest having a certain density difference or more from surrounding pixels and pixels on both sides thereof is extracted as a nozzle region of interest from the acquired density profile. Filters B to E, other than a filter A to be applied for density smoothing processing of pixels that do not belong to the nozzle region of interest, are applied for the density smoothing processing of the pixels in the nozzle region of interest, to generate a profile of a density correction value for eliminating a density difference between respective pixels based on the density profile after the smoothing processing.

There is disclosed a non-transitory machine-readable medium encoded with instructions executable by a processor and comprising instructions to: control print apparatus to print a test pattern 11 on a test region of a print medium 4; receive test data relating to the test pattern 11 printed on the print medium 4 from a sensor 8; analyse the test data with reference to baseline data to determine if the test pattern 11 satisfies a print quality criterion; output an instruction to operate the print apparatus in a first mode, in which a pre-printing treatment is not applied to the print medium, in response to determining that the test pattern 11 satisfies the print quality criterion, the pre-printing treatment comprising wiping a printing surface of the print medium with a wiper element 10, 20; and output an instruction to operate the print apparatus in a second mode, in which the pre-printing treatment is applied to the print medium 4, in response to determining that the test pattern 11 satisfies the print quality criterion.

There is disclosed a non-transitory machine-readable medium encoded with instructions executable by a processor and comprising instructions to: control print apparatus to print a test pattern 11 on a test region of a print medium 4; receive test data relating to the test pattern 11 printed on the print medium 4 from a sensor 8; analyse the test data with reference to baseline data to determine if the test pattern 11 satisfies a print quality criterion; output an instruction to operate the print apparatus in a first mode, in which a pre-printing treatment is not applied to the print medium, in response to determining that the test pattern 11 satisfies the print quality criterion, the pre-printing treatment comprising wiping a printing surface of the print medium with a wiper element 10, 20; and output an instruction to operate the print apparatus in a second mode, in which the pre-printing treatment is applied to the print medium 4, in response to determining that the test pattern 11 satisfies the print quality criterion.

A print head of an ink jet printer comprising: a cavity for the circulation of jets, delimited laterally by side walls, at least one nozzle for producing at least one ink jet in the cavity, at least one generator applying a charge to at least one ink jet, 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, a slot, open onto the exterior of the cavity, a 1.sup.st gutter for recovering drops or segments not intended for printing, a 2.sup.nd gutter for recovering drops or segments that are not deflected and not intended for printing, this 2.sup.nd gutter comprising an input slot and at least one suction channel, an actuator in order to actuate the 2.sup.nd gutter, a 1.sup.st detector to detect an electrical charge of drops recovered in the 2.sup.nd gutter for recovering when the latter is in a closed position and/or a detector to detect, without contact, the passing of charged drops when the 2.sup.nd gutter is in an open position.

A print head of an ink jet printer comprising: a cavity for the circulation of jets, delimited laterally by side walls, at least one nozzle for producing at least one ink jet in the cavity, at least one generator applying a charge to at least one ink jet, 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, a slot, open onto the exterior of the cavity, a 1.sup.st gutter for recovering drops or segments not intended for printing, a 2.sup.nd gutter for recovering drops or segments that are not deflected and not intended for printing, this 2.sup.nd gutter comprising an input slot and at least one suction channel, an actuator in order to actuate the 2.sup.nd gutter, a 1.sup.st detector to detect an electrical charge of drops recovered in the 2.sup.nd gutter for recovering when the latter is in a closed position and/or a detector to detect, without contact, the passing of charged drops when the 2.sup.nd gutter is in an open position.

There is provided a technology that enables reduction of an amount of data to be processed in testing a printed image printed on a printing medium. A printing apparatus includes a printing unit, a camera, and an image-data output unit. The printing unit is capable of printing plural categories of test patterns on the printing medium. The camera captures an image of a test pattern printed on the printing medium, and outputs acquired image data to the image-data output unit. The image-data output unit reduces an amount of data of the image data output from the camera, in accordance with the category of the test pattern, and outputs acquired image data to a test apparatus.