Patent ID: 7548326

Claim:
A method of adjusting an image recording apparatus that comprises a recording material supply section for supplying sheets of recording material, a conveyer device for conveying the recording material along a transport path, a recording device for recording an image on the recording material as being conveyed, and a skew correction device for correcting skew of the recording material on said transport path so as to make a leading edge of each sheet of the recording material be parallel to a main scan direction that is a widthwise direction of said transport path, said method comprising steps of: supplying first and second sheets of recording material from said recording material supplying section, said first and second sheets being different in length in a sub scan direction that is a lengthwise direction of said transport path; recording a test pattern on said first and second sheets of recording material by said recording device, to produce first and second test prints, said test pattern having a first line that is defined to be parallel to said sub scan direction; measuring distances from one side of each of said test prints to two different points of said first line as recorded on each of said test prints; calculating a skew degree of each of said first and second test prints from said measured two distances; calculating skew characteristics of each of said first and second sheets of recording material from said skew degrees of said first and second test prints, said skew characteristics being dependent upon a location of said recording material supply section and the lengths in the sub scan direction of said first and second sheets; and adjusting, based on the calculated skew characteristics, correction parameters for said skew correction device to correct skew of recording materials supplied from said recording material supply section; wherein said test pattern comprises a plural number of second lines defined to be parallel to the main scan direction, and a third line that is symmetrical to said first line about a referential line connecting center points of said second lines to each other, and said method further comprises steps of: calculating a variation of a print starting position in the main scan direction based on a difference between a distance from the one side edge to said first line and a distance from opposite side edge to said third line with respect to either of said test prints; and adjusting the print starting position in the main scan direction by controlling said recording device based on the calculated variation of the print starting position in the main scan direction.