RECTANGULAR-COORDINATE MEASURING APPARATUS HAVING IMPROVED INTERPOLATING CIRCUIT

摘要

PURPOSE: To improve an orthogonal coordinate measuring instrument incorporating an interpolation circuit and an interpolation method for measured values, having an optical displacement converter which transmits a quadrature phase analog output signal when the read head of the orthogonal coordinate measuring instrument traverses a fixed lattice. CONSTITUTION: An interpolation circuit converts an analog signal to a binary digital signal and reads an interpolation binary digital signal value sent to a read-only memory 38 and corresponding to a combination of digitalized output signals of the read head 22, using a high-speed A/D conveter 34. The interpolation signal value corresponds to the proportion of between-lines spaces which are traversed by the read head. The running count of transfers of most important bits of the interpolation signal value is maintained, and a signal value corresponding to the total of complete between-lines spaces traversed is obtained. The count of transfers and the interpolation signal, when combined, produce a signal corresponding to a between-lines and within-line total distance traversed by the read head.