主权项 |
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; an extraction unit configured to, in a temperature dropping process in a driving period of said heater detected by said temperature sensor, extract temperatures at a plurality of points of a predetermined time interval including a timing at which a feature point of a 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 in respect to time; an acquisition unit configured to acquire a first total sum of absolute values of differences between a predetermined addition threshold and second derivatives in the predetermined time interval and a second total sum of absolute values of differences between the predetermined addition threshold and the second derivatives up to a predetermined time within the predetermined time interval, based on second derivatives calculated by said arithmetic unit; and a judgment unit configured to judge, based on a predetermined first threshold used for judging normal discharge and a predetermined second threshold for judging discharge failure, from the first total sum acquired by said acquisition unit, whether normal discharge or discharge failure has occurred, and further judge, based on a predetermined third threshold, from the second total sum acquired by said acquisition unit, whether normal discharge or discharge failure has occurred, in a case where neither normal discharge nor discharge failure is judged. |