Improvement of asymmetrical speed signal for high frequency optical encoder

In order to improve the symmetry of a square wave corresponding to sinusoidal signals for a high frequency optical encoder, this paper studies the non-orthogonality of the signal width and the square wave from the high precision incremental optical encoder with a tenth harmanic generation and 3 240 gratings. The solution method to asymmetrical square signals is analyzed through reducing the proportion of high frequency signals in sinusoidal signals. The experimental results show that this method can solve the non-orthogonality of square wave in a slow measuring speed, and improve the asymmetry of square wave width. The rate of asymmetrical square wave is less than 4% that is expected.