Importance

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Abstract

In an ink jet print head including a plurality of ejection openings arranged therein for ejecting an ink, with the head carrying out printing by moving in a scanning direction relative to a printing medium, an ejection failure is detected promptly and accurately and adhesion of the ink to an ejection face on which the ejection openings are formed is also detected, without affecting print operation sequences. To achieve this, the following operations are performed: While an ink jet print head is being relatively moved in the scanning direction, a light beam is supplied diagonally of an arrangement direction of the plurality of ejection openings and in a direction traversing a trace of the ejected ink. The ink is ejected through the plurality of ejection openings in accordance with predetermined data, and a manner of ink ejection from each of the plurality of ejection openings is detected based on how the ejected ink is blocking the light beam. Based on the detection contents, it is also determined whether or not the ink adheres to the ejection face.

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First Claim