Patent ID: 6313857
Filing Date: 2001-11-06
Classification: B41J

Abstract:
A method for correcting density irregularity in image recording using a line head, comprising the steps of:printing a belt-like pattern at a pre-determined gradation value in a first main scanning direction which corresponds to a scanning direction of said line head;moving a line sensor relatively along said first main scanning direction while aligning a second main scanning direction, which corresponds to a scanning direction of said line sensor, with a subsidiary scanning direction, being substantially perpendicular to said first main scanning direction, to detect a printing-density value of said belt-like pattern;obtaining a correction condition for each pixel position based on detected said printing-density value and said predetermined-gradation value; andcorrecting image data for image recording on the basis of said correction condition, wherein:said belt-like pattern includes a plurality of belt-like pattern portions printed at least with two gradation values which are selected in proximity to said predetermined gradation value; andaverages of printing-density values are obtained from said plurality of belt-like pattern portions and said correction condition is set based on change ratios of said averages of printing-density values to said gradation values of the belt-like pattern portions.