Patent Number: 6,310,637

Title: Method of printing test pattern and printing apparatus for the same

Abstract: In a printer that allows dual-way printing, a test pattern is formed toadjust the print timing with a high accuracy, or more concretely toeliminate a deviation of dots created in the course of a main scan in abackward direction from dots created in the course of the main scan in aforward direction. The test pattern is based on a normal dither matrix.The test pattern includes a plurality of dots that are regularly arrangedboth in a main scanning direction and in a sub-scanning direction. Whenthe test pattern is printed at an appropriate timing, it is observed as asubstantially homogeneous state without unevenness of the density. In casethat the dot print timing is deviated, on the other hand, a deviation indot interval causes unevenness of the density. The deviation of the dotprint timing is accurately detected, based on the presence or thenon-presence of such unevenness of the density. When the interval of thedots is set equal to the interval that realizes a spatial frequency givinga high visual sensitivity, unevenness of the density is observable moreprominently. The deviation of the dot print timing may alternatively bedetected by taking advantage of a moire pattern, which is caused by anoverlap of an inspection pattern with oblique reference lines.

Inventors: Shimada; Kazumichi (Nagano-ken, JP), Liu; Sa (Nagano-ken, JP)

Assignee:

International Classification:

Expiration Date: 10/32013