Ink jet printer thermal control system

A thermal ink jet printer, comprising:

• a print head having a plurality of ejection nozzles from which droplets of ink may be ejected, and a thin film electrical resistance heater associated with each nozzle, the resistance heaters being deposited upon a substrate;
• a carriage that supports the print head and traverses it across a printing medium in a series of passes;
• a thin film temperature sensor deposited upon the same substrate as the thin film resistance heaters of the print head;
• and
• means for predicting the heat loading of the print head during a period of operation, prior to the commencement of the period of operation.

A thermal ink jet printer, comprising:

• a print head having a plurality of ejection nozzles from which droplets of ink may be ejected, and a thin film electrical resistance heater associated with each nozzle, the resistance heaters being deposited upon a substrate;
• a carriage that supports the print head and traverses it across a printing medium in a series of passes;
• a thin film temperature sensor deposited upon the same substrate as the thin film resistance heaters of the print head;
• means for predicting the heat loading of the ejector during a pass, prior to the initiation of the pass;
• and
• means for controlling the temperature of the print head responsive to the means for predicting.

A process for controlling the temperature of the ejector portion of the print head of a thermal ink jet printer, comprising the steps of:

• sensing the temperature of the ejector;
• predicting the future temperature of the ejector from the amount of printing to be accomplished by the ejector during a future period;
• and
• controlling the temperature of the ejector responsive to the prediction of future temperature so that the actual temperature of the ejector is maintained within an acceptable operating range.