Patent ID: 6943341

Claim:
A position measuring system, comprising: a scale comprising: an incremental graduation track of a defined incremental graduation period; and on at least one defined reference position, a reference marking field with a mean reference marking graduation period, wherein said mean reference marking graduation period differs from said incremental graduation period; a scanning unit movable with respect to said scale, said scanning unit comprising a plurality of scanning elements for generating scanning signals, wherein at least two phase-shifted incremental signals are generated as scanning signals; a first evaluation device arranged downstream of said scanning unit that determines a rough reference position from a maximum of resultant disturbance with said scanning signals at a defined relative position of said scale and said scanning unit; a second evaluation device arranged downstream of said scanning unit that determines a beat signal phase from a difference between a whole-number multiple of a reference pulse signal phase and a whole-number multiple of an incremental signal phase; and a third evaluation device arranged downstream of said first and second evaluation devices, which is suitable for unequivocally marking a beat signal period from said rough reference position and, if a defined phase position exists, to issue a fine reference position from said beat signal phase.