Estimation of Inkjet Printer Spur Gear Teeth Number from Pitch Data String of Limited Length

Abstract

In this paper, we investigate the feasibility of estimating the number of inkjet printer spur gear teeth from pitch data strings of limited length by maximum entropy spectral analysis. The purpose of this study is to improve the efficiency of inkjet printer model identification based on spur mark comparison in the field of forensic document analysis. Experiments were performed using two spur gears in different color inkjet printer models, and eight different lengths of pitch data strings--ranging from three to 10 times the number of spur gear teeth. The result for a data string longer than five times the number of teeth showed a proper estimation within a deviation of one tooth. However, the estimation failed for shorter data strings because the order in maximum entropy analysis was determined inappropriately. The presented results provide information on the number of spur gear teeth from shorter data strings than in a previous study.