Patent ID: 6942309

Claim:
A printing apparatus comprising: a printhead for ejecting ink from a plurality of sets of nozzles, the printhead comprising: a substrate; and a plurality of heaters arranged on the substrate for heating ink in the printhead to generate bubbles in the ink and eject the ink through corresponding nozzles; a data transducer for translating raw data into printing data; a counter for counting a total quantity of printing data value sent to each set of nozzles; a memory for storing the total quantity of printing data value corresponding to each set of nozzles; and a head driver circuit for generating printing signals and non-printing signals corresponding to each set of nozzles according to the printing data provided by the data transducer and the total quantity of printing data value stored in the memory, the printing signals controlling the heaters to generate sufficient heat energy to eject ink from the nozzles for printing data, and the non-printing signals controlling the heaters to generate heat energy that is not sufficient to eject ink from the nozzles for raising a temperature of the ink, the head driver circuit comprising: a signal generator for generating a plurality of printing signals and non-printing signals having unique energy values; a comparator for comparing the total quantity of printing data value stored in the memory with a plurality of reference values; and a selector circuit for selecting printing and non-printing signals generated by the signal generator to be sent to the corresponding set of nozzles based on the comparison results given by the comparator.