In the print position adjustment procedure when performing bidirectional printing by using a first head and a second head, patterns (A) and (B) are printed to adjust the print positions of the first and second heads relative to each other in each of the forward and backward directions. A pattern (C)...http://www.google.com.tw/patents/US6334720?utm_source=gb-gplus-share專利 US6334720 - Printing apparatus and method for correcting print positions
