The present invention is to provide, for each nozzle, a temperature sensor that detects a temperature change accompanying driving an ejection heater. In the temperature change, an inflection point appears when an ink is ejected normally. Then, calculated is a summation of absolute values of the differences...http://www.google.com/patents/US7963629?utm_source=gb-gplus-sharePatent US7963629 - Ejection status determining method for inkjet printing head
