Patent ID: 7448715
Filing Date: 2008-11-11
Classification: B41J

Abstract:
1. An ink jet printer, comprising: an endless belt having a width; a driving device that rotates the endless belt; a print head having a plurality of ink jet nozzles arranged along the width of the endless belt; a first detector that measures a moving speed of the endless belt at a first position; a second detector that measures a moving speed of the endless belt at a second position separated from the first position along the width of the endless belt; a paper sensor for detecting a timing when an upper edge of a printing sheet is transported to a position facing the paper sensor; an ink discharge time determiner that determines ink discharge time for each ink jet nozzle based on a timing when the paper sensor detects the upper edge of the printing sheet, a position of the ink jet nozzle along the width of the endless belt, a difference between a value detected by the first detector and a value detected by the second detector, and a pattern to be printed; and a standard time determiner that determines standard time for each ink jet nozzle based on the position of the ink jet nozzle along the width of the endless belt and the difference between the value detected by the first detector and the value detected by the second detector, wherein the standard time is determined by the following equation: wherein the standard time for an ink jet nozzle is a timing when the upper edge of the print sheet arrives at a position below the ink jet nozzle, and wherein the ink discharge fine determiner determines the ink discharge time for each ink jet nozzle based on the standard time determine by the standard time determiner and the pattern to be printed.