Development of a grating disk of a microrotary encoder for measurement of meshing accuracy of microgears

Grating disks of a microrotary encoder are developed to measure the rotational accuracy of microgears. In gear engagement, transmission error plays an important role to grasp the meshing performance of gear pairs. For measurement of transmission error of microgears, it is necessary to utilize a couple of microrotary encoders whose diameters are smaller than the reference diameter of microgears to be measured. The designed grating disk has a diameter of 1 mm, and the number of gratings is up to 1,000. It is manufactured with photo-lithography method on trial, and the grating patterns are successfully achieved homogeneously. The accuracy of the pitch and the line width is enough for realizing grating disks of a microrotary encoder.