Patent ID: 8733876
Filing Date: 2014-05-27
Classification: B41J

Abstract:
1. A printing apparatus comprising: a printhead including a heater configured to generate heat energy to discharge ink, and a temperature sensor configured to detect a temperature; a driving unit configured to drive said heater; a monitoring unit configured to monitor a temporal change in the temperature detected by said temperature sensor when said driving unit drives said heater; an extraction unit configured to, in a temperature dropping process in a driving period of said heater monitored by said monitoring unit, extract temperatures at a plurality of points of a predetermined time interval including a timing at which a feature point of the temporal change, in the temperature detected by said temperature sensor, which occurs when the ink is normally discharged by driving said heater, appears; an arithmetic unit configured to calculate a second derivative of the temperature extracted by said extraction unit with respect to time; an addition unit configured to acquire a total sum of values of second derivatives calculated by said arithmetic unit, which are weighted in accordance with an elapse of time; and a judgment unit configured to judge, based on a predetermined first threshold and the total sum acquired by said addition unit, whether normal discharge is obtained, or discharge failure has occurred.