Effect of shaft eccentricity on measurement signal of optical encoder

According to the measurement principle of Moire fringe, this paper explains the features of Moire fringe and analyzes the impact of eccentricity on signal. The breadth of fringe will change when the eccentricity of the optical encoder gratings changes. The fringe broadens when the eccentricity becomes smaller, and duty factor is bigger. When the eccentricity becomes greater, the fringe and the duty factor go the opposite way. The ranges of duty factor of the output signal are compared by measuring three kinds of optical encoders.