Patent ID: 6550150
Filing Date: 2003-04-22
Classification: G01C,G01D

Abstract:
A surveying instrument which incorporates a magnetic incremental rotary encoder, comprising:a magnetic drum provided on an outer peripheral surface with a multi-pole magnetized layer having, a plurality of equally-divided magnetized divisions; and two magnetic sensors, each of which detects a magnetic field generated by said multi-pole magnetized layer said magnetic drum and said two magnetic sensors configured for relative rotation therebetween; wherein each of said two magnetic sensors detects a variation in said magnetic field due to the relative rotation between said magnetic drum and said magnetic sensors to measure an angle of said relative rotation; and wherein said two magnetic sensors are arranged so that said magnetic sensors are offset from each other to have a phase angle of an odd-numbered pitch angle therebetween and such that said two magnetic sensors are located on opposing sectors of said magnetic drum offset from each other by approximately 180 degrees about an axis of said magnetic drum.