Position measuring apparatus

专利名称：Position measuring apparatus发明人：Akihiko Morishita,Osami Eda申请号：US08/249269申请日：19940525公开号：US05414516A公开日：19950509

摘要：A position measuring apparatus for obtaining position information by

processing a first and second sinusoidal signals with the phase difference of 90° obtainedby a detecting device in accordance with change of a position, comprises an adding andsubtracting device for generating a third sinusoidal signal by subtracting the secondsinusoidal signal from the first sinusoidal signal and a fourth sinusoidal signal by addingthe first and second sinusoidal signals, a maximum and minimum measuring device formeasuring respective maximum and minimum values of the first to fourth sinusoidalsignals, a processing device for calculating amplitudes and offsets of the respective firstand second sinusoidal signals based on the maximum and minimum values of the first andsecond sinusoidal signals measured by the maximum and minimum measuring device,obtaining fifth and sixth sunusoidal signals by standardizing the first and secondsinusoidal signals based on the obtained amplitudes and offsets, forming a seventhsinusoidal signal by subtracting the sixth sinusoidal signal from the fifth sinusoidal signaland an eighth sinusoidal signal by adding the fifth and sixth sinusoidal signals, correctingthe ratio of the seventh sinusoidal signal to the eighth sinusoidal signal based on theratio between respective amplitudes of the seventh and eighth sinusoidal signalsobtained by the use of the maximum and minimum values of the third and fourth

sinusoidal signals measured by the maximum and minimum measuring device, andobtaining the position information from the corrected value.

申请人：NIKON CORPORATION

代理机构：Shapiro and Shapiro

更多信息请下载全文后查看