Patent ID: 6896348
Filing Date: 2005-05-24
Classification: B41J

Abstract:
1. An ink jet printing apparatus based on a serial scan method which prints on a printing medium by using a print head formed with a plurality of nozzles through which ink can be ejected and selectively ejecting ink through the plurality of nozzles in said print head in accordance with dot patterns of dot matrices corresponding to respective gradation values, on the basis of image data converted into n values, where n≧3, using gradation patterns for a systematic dither method, the apparatus comprising: main scanning means for scanning said print head over said printing medium in a sub-scanning direction different from a direction in which said nozzles are arranged; conveying means for conveying said printing medium by a predetermined amount K, where K=a×L, wherein a is a natural number and L is . . . are arranged, or K=L/b, wherein b is a natural number, in the direction in which said nozzles are arranged, between a preceding scan and a next scan of the print head executed by said main scanning means; first changing means for shifting correspondences between the image data and said plurality of nozzles in the direction in which said nozzles are arranged; and second changing means for changing operated dot patterns so as to allow the selective use of a plurality of different dot patterns indicating the same gradation value.