码盘偏心对叠栅条纹信号相位影响的理论分析

增量式光学编码器根据径向辐射光栅产生的叠栅条纹进行角度测量，两光栅码盘轴之间及其与系统转动轴之间的偏心和晃动，影响着编码器读头输出的叠栅条纹信号的相位，这给角度测量带来了一定的系统误差。根据光栅码盘产生叠栅条纹的基本理论，在改进计量光栅码盘理论模型的基础上，推导出码盘偏心情况下码盘读头输出的叠栅条纹信号相位的理论公式，对码盘偏心给叠栅条纹信号相位带来的偏差、增量式光学编码器光学设计原理及消除此由此带来的系统误差的技术原理进行了分析与讨论。

Theoretical Analysis on Phase of Moiré Fringes′Signal Affected by Shaft Eccentricity

Incremental optical encoder measures length and angle based on the principle of moiré fringes. The eccentricity and shaking of two disks′ axis may affect the phase of moiré fringes signal detected by encoder readout. This phase error may cause systematic error on angle measuring. According to the elementary theory of two grating disks forming moiré fringes, an improved model of optical encoder was proposed, and theoretical formula on phase of moiré fringes taking account of shaft eccentricity was deduced. This phase error caused by shaft eccentricity, the principle of designing incremental optical encoder and dispelling the systematic error were analyzed and discussed.