Determining the operating energy of a thermal ink jet printhead using an onboard thermal sense resistor

A method for operating a thermal ink jet printer including a printhead having ink firing resistors responsive to pulses provided to the printhead, the pulses having a voltage, a pulse width, and a pulse energy defined by the voltage and pulse width of a pulse, comprising the steps of:

• (A) applying to the printhead a sequence of pulse bursts of respective increasing pulse energies that span a predetermined pulse energy range, each pulse burst comprised of a plurality of pulses having a pulse energy that is associated with such pulse burst and is constant for all pulses in such burst, and each burst having a sufficient number of pulses to allow the printhead to achieve a steady state operating temperature at the pulse energy of the pulse burst;
• (B) sampling a steady state operating temperature of the printhead for each of the sequence of pulses bursts of different pulse energies to produce a set of temperature samples respectively associated with the increasing pulse energies;
• (C) analyzing the temperature samples to determine a turn on pulse energy from the temperature samples;
• and
• (D) operating the thermal ink jet printhead with a pulse energy that is greater than the turn on pulse energy and in a range that provides a desired print quality while avoiding premature failure of the heater resistors.