Patent ID: 7175252
Filing Date: 2007-02-13
Classification: B41J

Abstract:
1. An ink jet printing apparatus to form an image on a print medium by ejecting ink onto the print medium from a plurality of nozzles arrayed in a print head, the printing apparatus comprising: recovery means to recover a normal ink ejection state of each nozzle in the print head; recovery operation determining means for dividing the nozzles into a plurality of blocks, the nozzles divided into the plurality of blocks forming a nozzle array, the plurality of blocks being divided in a length direction of the nozzle array, counting the number of ejections from the nozzles in each block and, based on the accumulated number of ejections for each block, determining whether or not to execute a recovery operation of said recovery means, wherein said recovery operation determining means determines to execute the recovery operation on the print head when at least one of the accumulated numbers of ejections for the individual blocks reaches a predetermined threshold; and accumulated ejection number correction means to correct by a weighting value the accumulated number of ejections counted for each block, wherein said recovery operation determining means compares the accumulated numbers of ejections corrected by said accumulated ejection number correction means with the predetermined threshold, and wherein said accumulated ejection number correction means increases the weighting value as the position of the associated nozzle block is farther away from an ink supply port of the print head and multiplies the accumulated number of ejections by the associated weighting value to correct the accumulated number of ejections.