Method and apparatus for selecting ink ejection nozzles in multi-chip print heads

A method for controlling a micro-fluid ejection head comprising at least a first heater chip and a second heater chip, each having an array of nozzles from which ink is ejected in raster lines to form a printed image, where the first and second heater chips are disposed in a staggered overlapping arrangement such that a number of the nozzles of the first heater chip are substantially aligned with a corresponding number of the nozzles of the second heater chip in an overlapping region comprising N number of sub-regions, the method comprising:

• (a) determining a difference in temperature between a temperature of the first heater chip and a temperature of the second heater chip, where the temperatures of the first and second heater chips are determined based at least in part on density of image data for a previous raster line of the printed image and density of image data for a current raster line of the printed image;
• (b) based on the difference in temperature, determining a first percentage of nozzles in each sub-region of the first heater chip to be used in printing a first portion of the printed image;
• (c) based at least in part on the difference in temperature, determining a second percentage of nozzles in each sub-region of the second heater chip to be used in printing a second portion of the printed image;
• (d) based at least in part on the first percentage, selecting particular nozzles in each sub-region of the first heater chip to be used in printing the first portion of the printed image;
• (e) based at least in part on the second percentage, selecting particular nozzles in each sub-region of the second heater chip to be used in printing the second portion of the printed image, where the second nozzle of the second heater chip are not aligned with the selected nozzles of the first heater chip;
• and
• (f) printing at least the first and second portions of the printed image using the selected nozzles of the first heater chip and the selected nozzles of the second heater chip.

An inkjet printer for receiving print data from a host computer and for generating a printed image based on the print data, the inkjet printer comprising:

• a wide-swath micro-fluid ejection head comprising:
• a first heater chip having an array of nozzles from which ink is ejected in raster lines to form a first portion of the printed image;
• and
• a second heater chip having an array of nozzles from which ink is ejected in raster lines to form a second portion of the printed image, the second heater chip disposed in relation to the first heater chip in a staggered overlapping arrangement such that a number of the nozzles of the first heater chip are substantially aligned with a corresponding number of the nozzles of the second heater chip in an overlapping region comprising N number of sub-regions;
• means for determining a difference in temperature between a temperature of the first heater chip and a temperature of the second heater chip, wherein the temperatures of the first and second heater chips are determined based at least in part on density of image data for a previous raster line of the printed image and density of image data for a current raster line of the printed image;
• means for determining a first percentage of nozzles in each sub-region of the first heater chip to be used in printing a first portion of the printed image, where the first percentage is determined based at least in part on the difference in temperature;
• means for determining a second percentage of nozzles in each sub-region of the second heater chip to be used in printing a second portion of the printed image, where the second percentage is determined based at least in part on the difference in temperature;
• means for selecting nozzles in each sub-region of the first heater chip to be used in printing the first portion of the printed image, where the nozzles are selected based at least in part on the first percentage;
• and
• means for selecting nozzles in each sub-region of the second heater chip to be used in printing the second portion of the printed image, where the selected nozzles of the second heater chip are not aligned with the second nozzles of the first heater chip, and where the nozzles are selected based at least in part on the second percentage.

A method for controlling a micro-fluid ejection head comprising at least a first heater chip and a second heater chip, each having an array of nozzles from which ink is ejected in raster lines to form a printed image, where the first and second heater chips are disposed in a staggered overlapping arrangement such that a number of the nozzles of the first heater chip are substantially aligned with a corresponding number of the nozzles of the second heater chip in an overlapping region, the method comprising:

• (a) determining a difference in temperature between a temperature of the first heater chip and a temperature of the second heater chip;
• (b) based at least in part on the difference in temperature, determining a first number of nozzles of the first heater chip to be used in a print operation;
• (c) based at least in part on the difference in temperature, determining a second number of nozzles in of the second heater chip to be used in the print operation;
• and
• (d) performing the print operation using the first number of nozzles the first heater chip and the second number of nozzles of the second heater chip.