| 摘要 |
PURPOSE:To detect the relative movement displacement attaining a set value with good accuracy even in case the intervals of an optical grating are large by providing a displacement signal generating means, a reference mark signal generating means, the 1st intersection detecting means, the 2nd intersection detecting means and a position specifying means, etc. CONSTITUTION:The fixed optical grating 30 and the movable optical grating 34 are provided to the fixed side and the movable side of an object to be detected respectively and the displacement signal generator 66 generating a displacement signal Vx changing periodically with the relative displacement between the objects to be detected and the reference mark signal generator 70 generating a reference mark signal Vm changing almost in a straight line extending over 1/2 period of the signal Vx are provided. Further, the 1st comparator 68 comparing the signal Vx with the 1st reference signal and detecting the 1st intersection which is its intersection, the 2nd comparator 72 comparing the signal Vm with the 2nd reference signal and detecting the 2nd intersection which is its intersection and a position specifying circuit 76 making the 1st intersection after the set number counting from the 2nd intersection the origin where the relative movement displacement attains the set value are provided to form the titled detector. |
