This paper discusses oscillation mechanism of a cleaning blade in a laser printer. Although this problem has been known for many years, the details of oscillation mechanism is not clarified, so we have not found out the fundamental solution yet. In order to clarify the mechanism, we direct our attention to a coupled-mode flutter model in multi degrees of freedom system, and then we formulate an equation of motion. Then, we verify a stability of the system and formulate equation of steady-state amplitude of unstable vibration due to a coupled mode flutter by nonlinear analysis of the system. Finally, we reveal a validity of our study by a comparison between an experiment and a numerical simulation of some modified blades.
