Importance

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Abstract

The present invention relates to an electrostatic capacity type encoder which includes a variable capacitance mechanism made on two dimensional planes, random time varying excitation generation system, interlaced fine & coarse cycles and digital signal processing unit. A variable capacitance mechanism which includes stationary and rotating disks facing each other and forming one or more variable capacitors. The transmit electrodes are split to two transmit phases and the receive electrodes to two receive phases, both can be implemented on two dimensional printed circuit boards without third dimension via interconnects. The combination of the 2 by 2 grid provides the four combinations required to detect both position and direction. Another configuration is made of electrostatic capacity type encoder which includes a first and second stationary disks and in between a third rotating disk, made either of a dielectric material with varying geometry or thickness or from a conductive patterns printed on a PCB. A time varying excitation system with no fundamental frequency is described to improve the robustness to external noise and omit the necessacity of excessive shielding. Interlacing mechanism is explained to put several different encoders channels on the same perimeter, minimizing encoder mechanical dimensions. To complete the sensor a digital signal processing unit is presented, where the capacitance value is converted to conventional encoder formats.

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First Claim