Patent ID: 7204347

Claim:
A position detecting device for detecting the position of an object ( 12 ) movable along a predetermined path of movement, comprising: a signal transmission medium ( 13 ) extending along the path of movement; a signal generator ( 15 ) movable together with said movable object ( 12 ), by means of which a signal can be coupled into the signal transmission medium ( 13 ) at a coupling location thereof changing in accordance with the movement of said signal generator ( 15 ); at least one signal receiver ( 29 , 33 ) at an extraction location in an end portion of said path of movement, by means of which the signal can be extracted from the signal transmission medium ( 13 ); a signal propagation time measuring means ( 35 , 37 ) adapted to determine the signal propagation time between coupling location and extraction location by evaluating the signal extracted at the extraction location; and a processing means ( 45 ) adapted to derive from the signal propagation time ascertained a position signal indicating the instantaneous position of the object ( 12 ) along the path of movement; wherein the signal generator ( 15 ) is designed to deliver a periodically repeating signal pulse sequence ( FIG. 2 ) in which the time intervals between consecutive signal pulses are different for each pair of consecutive signal pulses, the period duration of the repetitive signal pulse sequence is greater than the maximum signal propagation time with maximum distance between coupling location and extraction location, and the time intervals between consecutive signal pulses are shorter than the maximum signal propagation time.