Patent ID: 6938994

Claim:
A method of operating an ink jet printhead within a predetermined temperature range to print an image, said printhead comprising: an array of nozzles formed on a substrate, each nozzle including a nozzle opening, a displaceable thermal actuator for ejecting ink through said nozzle opening and an ink chamber; an activation unit for each nozzle 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 that are insufficient to cause the ejection of ink from said printhead; and, (e) utilizing said printhead to print said image once the temperature of said substrate reaches said predetermined threshold.