Coordinate measuring machine with improved interpolation circuit.

摘要

An interpolation circuit and process is described incorporated into a coordinate measuring machine having optical displacement transducers generating quadrature analog output signals as a reading head traverses past a stationary grating. The interpolation circuit and process use high speed A/D converters to convert the analog signals to binary digital form, each combination of digitized signals applied to a read only memory to cause read out of a previously computed and stored interpolation binary digital signal value corresponding to the combination of digitized reading head output signals, the interpolation signal values correspond to the proportion of interline space traversed by the reading head. A running count of the transitions of the most significant bits of the interpolation signal value is also maintained to obtain a signal value corresponding to the total of intraline complete spaces traversed. The transition count and interpolation signals are combined to provide a signal corresponding to the total intraline and interline distance traversed by the reading head. <IMAGE>