Keiji KATAOKA

Ricoh Printing Systems, Ltd., 1060 Takeda, Hitachinaka, Ibaraki 312-8502, Japan

(Received October 31, 2007; Accepted June 10, 2008)

In the slant scanning method of multiple beams a misalignment of the slant angle causes a beam spacing error and pitch irregularities of scan lines called “banding”. This paper evaluates the pitch irregularities and tries to clarify the allowable beam spacing error. The following results are obtained: (1) The maximum spacing error of print lines is proportional to m/(dpi), where m is the number of multiple beams and dpi print dot density. (2) The noticeable limit of periodic variations of print density at low spatial frequency was presumed to be a visibility between 1 and 2% in experiments. (3) The allowable beam spacing error was calculated introducing the human eye spatial frequency response. (4) The banding simulation experiments by laser recording on the photographic paper on the XY stage showed good coincidence with the theoretical evaluations.

Key words: multiple beams, banding, pitch irregularity, slant scanning, laser printer