Apparatus and method for measuring rotational position

摘要

An apparatus and method for measuring the relative circumferential setting of at least two rotating elements of a machine for operating on a moving web are provided wherein a first of the elements serves as a measurement reference. An electric reference pulse is generated for each revolution of the first element, along with a train of clock pulses wherein each count corresponds to an increment of rotation. A marker pulse is generated for each revolution of the second element, and the count pulses generated subsequent to generation of a reference pulse and up to and simultaneous with generation of the next succeeding marker pulse are counted, thereby providing a relative rotational measurement. The count is retained in a memory until the next succeeding count is completed. A mechanism for making circumferential adjustments to the second element is provided, along with generator for generating adjustment pulses for each increment of adjustment, a number corresponding to the number of adjustment pulses being added to or subtracted from the count retained within the memory. The retained number as updated is displayed in an appropriate manner.