Capacitance type displacement measuring instrument

A capacitance type displacement measuring instrument having two members movable relative to each other in a moving direction and carrying electrodes thereon, wherein a change in electric capacity between the electrodes due to a change in displacement between the two members is detected on the basis of a change in phase of a detection signal and a displacement value between said two members is measured from the change in the capacity, said measuring instrument comprising:

• an oscillator for generating an alternating current (AC) signal of a predetermined amplitude;
• a multiplexer for successively sampling the AC signal from said oscillator;
• transmitting electrodes provided on one of said members, said transmitting electrodes being arranged to correspond to at least one cycle of said AC signal at a predetermined pitch in the moving direction of said member, said AC signal being successively applied by said multiplexer to successive transmitting electrodes;
• a plurality of transfer electrodes provided on the other of said members, said transfer electrodes being arranged at a predetermined pitch differing from the predetermined pitch of said transmitting electrodes, part of said transfer electrodes being opposed to said transmitting electrodes;
• at least one pickup electrode provided on said one of said members and opposed to a remaining part of the transfer electrodes;
• and
• phase detecting means for detecting a change in phase of pickup signals of a substantially triangular waveform detected by said at least one pickup electrode.