The invention describes a number of methods and apparatus for shortening the inter-message gap on a continuous inkjet printer. Included is a novel phase testing methodology.

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.

A compensation method includes determining position information of an abnormal nozzle of an inkjet head; acquiring printing parameters, determining first data corresponding to the abnormal nozzle, and based on the position information of the abnormal nozzle and the printing parameters, determining position information of a compensation nozzle for compensating the first data corresponding to the abnormal nozzle; and based on the printing parameters, acquiring second data of the compensation nozzle in a normal printing state which includes ink out data and ink holding data, determining an address of the ink holding data, and generating compensation data by writing the first data into the address of the ink holding data. A compensation device includes: an abnormal nozzle position determination module; a compensation nozzle position determination module; and a compensation data generation module. An inkjet printer includes: a controlling unit, an inkjet head unit, and a nozzle compensation unit.

A compensation method includes determining position information of an abnormal nozzle of an inkjet head; acquiring printing parameters, determining first data corresponding to the abnormal nozzle, and based on the position information of the abnormal nozzle and the printing parameters, determining position information of a compensation nozzle for compensating the first data corresponding to the abnormal nozzle; and based on the printing parameters, acquiring second data of the compensation nozzle in a normal printing state which includes ink out data and ink holding data, determining an address of the ink holding data, and generating compensation data by writing the first data into the address of the ink holding data. A compensation device includes: an abnormal nozzle position determination module; a compensation nozzle position determination module; and a compensation data generation module. An inkjet printer includes: a controlling unit, an inkjet head unit, and a nozzle compensation unit.

Certain examples described herein relate to color calibration. In certain cases, a plurality of test patches are printed with a printing system, the test patches corresponding to a set of initial color sample points and a set of test colors. Color properties of the printed test patches are measured. In certain examples, a gamut descriptor is identified from a plurality of gamut descriptors using the color properties of the test colors. Each gamut descriptor defines a set of up-sampling parameters for a particular color gamut. Measured color properties for the initial color sample points are up-sampled using the set of up-sampling parameters for the identified gamut descriptor to generate up-sampled data. In certain cases, the up-sampled data is used to generate a color mapping to be applied to print job data received by the printing system.

Certain examples described herein relate to color calibration. In certain cases, a plurality of test patches are printed with a printing system, the test patches corresponding to a set of initial color sample points and a set of test colors. Color properties of the printed test patches are measured. In certain examples, a gamut descriptor is identified from a plurality of gamut descriptors using the color properties of the test colors. Each gamut descriptor defines a set of up-sampling parameters for a particular color gamut. Measured color properties for the initial color sample points are up-sampled using the set of up-sampling parameters for the identified gamut descriptor to generate up-sampled data. In certain cases, the up-sampled data is used to generate a color mapping to be applied to print job data received by the printing system.

Image content is printed on a receiver medium using a continuous inkjet printer with a linear printhead. A plurality of segments of the linear printhead are designated at different cross-track positions. The linear printhead is translated relative to a receiver medium such that an initial segment of the linear printhead is aligned with a printing region on the receiver medium and the image content is printed using the initial segment of the linear printhead. When an image quality level of the printed image content is determined to fall below an acceptable level, the linear printhead is translated relative to the receiver medium such that a next segment of the linear printhead is aligned with the printing region and the image content using the next segment of the linear printhead.

Image content is printed on a receiver medium using a continuous inkjet printer with a linear printhead. A plurality of segments of the linear printhead are designated at different cross-track positions. The linear printhead is translated relative to a receiver medium such that an initial segment of the linear printhead is aligned with a printing region on the receiver medium and the image content is printed using the initial segment of the linear printhead. When an image quality level of the printed image content is determined to fall below an acceptable level, the linear printhead is translated relative to the receiver medium such that a next segment of the linear printhead is aligned with the printing region and the image content using the next segment of the linear printhead.

Provided are a method for operating a CIJ printer with an optical monitoring means (80) having the steps of generating a bitmap (90,180) of the printed image to be printed, sequential controlling of charge electrodes (25) and/or deflection electrodes (30) of the CIJ printer, in order to generate dots or groups of dots of the bitmap (90,190) by applying ink droplets (12) to a substrate (100) to be printed and thus to sequentially apply a real printed image (195) to the substrate (100), capturing the real printed image (195) applied to the substrate (100) with the optical monitoring means (80), and automated comparing of the bitmap (90,190) of the desired printed image and of the real printed image (195) which has been applied to the substrate (100) and has been captured with the optical monitoring means (80), wherein the bitmap (90,190) of the desired printed image and the real image applied to the substrate (100) are automatically compared either on the basis of rows or columns of the bitmap (90,190) or on the basis of components of rows or columns of the bitmap (90,190), a CIJ printer for carrying out such a method and a method for teaching-in an optical monitoring means (80) of such a CIJ printer.