Patent ID: 6808253
Filing Date: 2004-10-26
Classification: B41J

Abstract:
A method of operating a page width ink jet printhead within a predetermined thermal range to print an image, said printhead comprising:an array of nozzles formed on a substrate, each nozzle including a nozzle opening, an associated displaceable thermal actuator for ejecting ink through said nozzle opening, an ink chamber and an activation unit for controlling operation of said actuator; at least one temperature sensor attached to said substrate for sensing the temperature of said substrate; a temperature determination unit connected to said at least one temperature sensor; and, an ink ejection drive unit coupled to said temperature determination unit and to said printhead; said method including the steps of: (a) sensing the temperature of said substrate with said at least one temperature sensor and said temperature determination unit; (b) said ink ejection drive unit determining if said temperature is below a predetermined threshold; (c) if said temperature is below said predetermined threshold, performing a preheating step of heating said actuators so that the printhead is heated to a temperature above said predetermined threshold; (d) controlling said preheating step such that said thermal actuators are heated by pulses of energy less than 160 nJ, which are insufficient to cause the ejection of ink from said printhead, ejection of one ink drop from one said nozzle requiring at least 160 nJ; and, (e) utilizing said printhead to print said image.