A printer having a printhead configured to print to a print medium; a camera configured to photograph the print medium; a carriage configured to support and move the printhead and the camera; and a processor configured to print, by the printhead, on the print medium a first test pattern that is larger than an imaging area of the camera, photograph the first test pattern by the camera, and detect a printing defect based on a result of the photograph.

A printer having a printhead configured to print to a print medium; a camera configured to photograph the print medium; a carriage configured to support and move the printhead and the camera; and a processor configured to print, by the printhead, on the print medium a first test pattern that is larger than an imaging area of the camera, photograph the first test pattern by the camera, and detect a printing defect based on a result of the photograph.

A printing device comprising a printing head including a plurality of nozzles configured to discharge ink to a printing medium are arranged, and a control unit configured to control discharge of the ink. The printing head is configured to discharge the ink along with scanning that is a relative movement in a predetermined direction with respect to the printing medium, and in test printing for printing a TP on the printing medium, the control unit performs control such that the ink of a first discharge amount is discharged from the nozzles when a color difference between the TP and the printing medium is greater than a predetermined threshold value, and the ink of a second discharge amount that is greater than the first discharge amount is discharged when the color difference between the TP and the printing medium is equal to or smaller than the threshold value.

A printing device comprising a printing head including a plurality of nozzles configured to discharge ink to a printing medium are arranged, and a control unit configured to control discharge of the ink. The printing head is configured to discharge the ink along with scanning that is a relative movement in a predetermined direction with respect to the printing medium, and in test printing for printing a TP on the printing medium, the control unit performs control such that the ink of a first discharge amount is discharged from the nozzles when a color difference between the TP and the printing medium is greater than a predetermined threshold value, and the ink of a second discharge amount that is greater than the first discharge amount is discharged when the color difference between the TP and the printing medium is equal to or smaller than the threshold value.

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.

Examples describe a method in which first and second test patterns are printed onto a print medium. The first and second test patterns each vary in print density in opposing directions. A location is determined along the first and second test patterns having at least substantially equal visual density

A method for testing at least one nozzle of a multi-jet print head of an inkjet printer including a plurality of nozzles (4), at least one 1.sup.st and one 2.sup.nd deviation electrode (14a, 14b) for each jet, method in which: at least one jet is formed using the nozzle (9), at a drop formation frequency, an estimate is made of:

a cutoff frequency (Fc) of at least this jet, by variation of the jet formation frequency, at a constant jet velocity, or, at constant formation frequency of the drops from at least this jet, by variation of the jet velocity, the velocity at which the cutoff frequency (Fc) is equal to the formation frequency; this cutoff frequency (Fc) or this velocity is compared with a reference value and the functional or non-functional state of at least the nozzle is deduced.

The invention relates to a method for detecting the presence of a jet from a multi-jet print head of an inkjet printer comprising a plurality of nozzles (4), at least one 1.sup.st and one 2nd deviation electrode (14a, 14b) for each jet, in which: the inkjet is produced by one of the nozzles, at a frequency and is then charged by a voltage V.sub.THT at a frequency f.sub.THT, f.sub.THT not being an integer multiple or sub-multiple of f.sub.stim1; a jet charge signal is detected, derived from sampling, at frequency f.sub.stim1, of the voltage at frequency f.sub.THT, at least one spectral component of this signal being used to detect the presence of the jet.

An ejection malfunction nozzle detecting unit prints plural test patterns on a print sheet using a recording head, and detects ejection malfunction nozzles on the basis of scanned images of the plural test patterns. The plural test patterns are line-shaped or band-shaped images for which a correction process has been performed at plural nozzle positions with a predetermined period. The nozzle positions of the plural test patterns are specified with offset positions different from each other. Further, the ejection malfunction nozzle detecting unit (a) determines a test pattern that densities at periodical ejection malfunction positions have been corrected among the plural test patterns on the basis of density distributions of scanned image of the test patterns, and (b) stores as ejection malfunction nozzle data an offset position of the determined test pattern into a storage device.