| 摘要 |
A plurality of ejection openings of an ink-jet head are divided into four blocks and ink ejection is performed for each block. An output of a photosensor which depends upon a number of ejected ink droplets interrupting light at a photosensor is sampled. On a basis of the sensor output, judgement is made whether ejection failure is present of the relevant block. This in ejection openings process is performed sequentially for other blocks. By this, even when a given rate of error is present in detecting precision of the photosensor, since overall number of ejection openings for which the detection is made is smaller, the number of faulty ejection openings which cannot be detected can be made smaller.
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