Capacitor-coupled ohmic resistance position sensor

An apparatus for measuring position of a target member comprising in combination:

• a) at least a pair of elongated members disposed in a parallel relationship therebetween, wherein at least one of the pair of elongated members has a high ohmic resistance per unit length of the elongated member;
• b) a target member providing a capacitive electrical coupling between the pair of elongated members and disposed simultaneously adjacent to the pair of elongated members in a relationship allowing movement of the target member relative to and following a length of the combination of the pair of elongated members, wherein the target member capacitively couples two alternating electrical signals respectively flowing through the pair of elongated members;
• c) means for supplying a first alternating electrical signal oscillating at a frequency to at least one of two opposite extremities of one of the pair of elongated members;
• d) means for taking off a second alternating electrical signal oscillating at said a frequency and associated with the first alternating electrical signal from one extremity of the other of the pair of elongated members located on one side of the target member;
• e) means for measuring amplitude of the first alternating electrical signal and amplitude of the second alternating electrical signal;
• and
• f) means for determining position of the target member with respect to a reference section stationary relative to the pair of elongated members as a function of the amplitudes of the first and second alternating electrical signal.