Swath density control to improve print quality and extend printhead life in inkjet printers

A method of controlling average printing density over time in an inkjet printer having a printhead with a plurality of nozzles arranged in one or more columns to produce full-height print swath across a print medium, comprising the following steps:

• passing the printhead repeatedly across a print medium in individual swaths;
• firing individual nozzles repeatedly during each printhead swath to apply an ink pattern to the print medium;
• detecting a delay in receiving incoming print data prior to a particular swath;
• in response to detecting a delay in receiving incoming print data, using only a subset of the nozzles during said particular swath to produce a reduced-height swath with reduced print density, in order to maintain a uniform swath repetition rate.

A method of controlling average printing density over time in an inkjet printer having a printhead with a plurality of nozzles arranged in one or more columns to produce full-height print swath across a print medium, comprising the following steps:

• passing the printhead repeatedly across a print medium in individual swaths,
• firing individual nozzles repeatedly during each printhead swath to apply an ink pattern to the print medium;
• using only a subset of the nozzles during a particular swath to produce a reduced-height swath with reduced print density;
• monitoring actual swath dot density and peak temperature of the printhead during each printhead swath;
• repeatedly calculating a maximum permissible swath dot density in response to the monitoring step as a function of the actual swath dot density and peak temperature, wherein the maximum permissible swath dot density results in a peak printhead temperature that does not exceed a maximum permissible peak printhead temperature;
• limiting swath dot density to no greater than the maximum permissible swath dot density during individual printhead swaths.

A method of controlling average printing density over time in an inkjet printer having a printhead with a plurality of nozzles arranged in one or more columns to produce full-height print swath across a print medium, comprising the following steps:

• passing the printhead repeatedly across a print medium in individual swaths;
• firing individual nozzles repeatedly during each printhead swath to apply an ink pattern to the print medium;
• prior to a particular printhead swath, predicting whether the swath has a printhead density that would lower ink supplies to the nozzles to unacceptably low levels;
• if the printhead density of said particular printhead swath is predicted to lower ink supplies to the nozzles to unacceptably low levels, using only a subset of the nozzles during said particular swath to produce a reduced-height swath with reduced print density.

A method of controlling average printing density over time in an inkjet printer having a printhead with a plurality of nozzles arranged in one or more columns to produce full-height print swath across a print medium, comprising the following steps:

• passing the printhead repeatedly across a print medium in individual swaths;
• firing individual nozzles repeatedly during each printhead swath to apply an ink pattern to the print medium;
• calculating swath dot density prior to each swath;
• if the swath dot density of an upcoming swath is greater than a maximum permissible swath density, using only a subset of the nozzles during the upcoming swath to produce a reduced-height swath with reduced print density.

An inkjet printer that applies an ink pattern to a print medium, the printer comprising:

• control logic;
• a printhead that is responsive to the control logic to pass repeatedly across the print medium in individual swaths, the printhead having individual nozzles that are fired repeatedly during each printhead swath to apply an ink pattern to the print medium;
• the control logic being configured to perform steps comprising:
• calculating swath dot density prior to each swath;
• if the swath dot density of an upcoming swath is greater than a maximum permissible swath density, using only a subset of the nozzles during the upcoming swath to produce a reduced-height swath with reduced print density.

A method of controlling printhead temperature in an inkjet printhead having a plurality of nozzles, comprising the following steps:

• passing the printhead repeatedly across a print medium in individual swaths;
• firing individual nozzles repeatedly during each printhead swath to apply an ink pattern to the print medium;
• monitoring actual swath dot density and peak temperature of the printhead during each printhead swath;
• repeatedly calculating a maximum permissible swath dot density in response to the monitoring step as a function of the actual swath dot density and peak temperature, wherein the maximum permissible swath dot density results in a peak printhead temperature that does not exceed a maximum permissible peak printhead temperature;
• limiting swath dot density to no greater than the maximum permissible swath dot density during individual printhead swaths.

A method of controlling printhead temperature in an inkjet printhead having a plurality of nozzles, comprising the following steps:

• passing the printhead repeatedly across a print medium in individual swaths;
• firing individual nozzles repeatedly during each printhead swath to apply an ink pattern to the print medium;
• monitoring actual swath dot density and peak temperature of the printhead during each printhead swath;
• repeatedly calculating a maximum permissible swath dot density in response to the monitoring step as a function of the actual swath dot density and peak temperature, wherein the maximum permissible swath dot density results in a peak printhead temperature that does not exceed a maximum permissible peak printhead temperature;
• using only a subset of the individual nozzles during a particular printhead swath to limit swath dot density to no greater than the maximum permissible swath dot density.

An inkjet printer that applies an ink pattern to a print medium, the printer comprising:

• control logic;
• a printhead that is responsive to the control logic to pass repeatedly across the print medium in individual swaths, the printhead having individual nozzles that are fired repeatedly during each printhead swath to apply an ink pattern to the print medium;
• a temperature sensor associated with the printhead, the temperature sensor being operably connected to supply a printhead temperature measurement to the control logic;
• the control logic being configured to perform steps comprising:
• monitoring actual swath dot density and peak temperature of the printhead during each printhead swath;
• repeatedly calculating a maximum permissible swath dot density in response to the monitoring step as a function of the actual swath dot density and peak temperature, wherein the maximum permissible swath dot density results in a peak printhead temperature that does not exceed a maximum permissible peak printhead temperature;
• limiting swath dot density to no greater than the maximum permissible swath dot density during individual printhead swaths.