Electrostatic capacity type encoder

Claim 1

An electrostatic capacity type encoder comprising: a rotary disk rotatingly secured to a rotary shaft of an encoder body; and a first stationary disk and a second stationary disk fixed to the encoder body facing in parallel to each other with said rotary disk arranged therebetween, a plurality of transmitting electrodes to which alternating currents from a source of electrical power with respective different phases are applied and said transmitting electrodes transmits a signal, wherein said transmitting electrodes are arranged on a flat surface of said first stationary disk at an equal distance therebetween along its circumference, a plurality of receiving electrodes for receiving said signal from the transmitting electrodes are provided on one side of said rotary disk facing said transmitting electrodes on the first stationary disk, a coupling electrode connected to said plurality of receiving electrodes for receiving said signal from said receiving electrodes is provided on the other side of the rotary disk, and an output electrode for receiving said signal from said coupling electrode is provided on one side of said second stationary disk facing said coupling electrode, whereby the amount of relative rotating displacement of said rotary disk to said first stationary disk is determined by a signal detector based on periodic variations in electrostatic capacity signals which are outputted from said output electrode.