Robust rotary encoder for power tool

• Main Author: Lewerentz Jan Hans Tolly
• Format: Patent
• Language: English
• Published: 03.04.2018
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; MEASURING; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; PHYSICS; TARIFF METERING APPARATUS; TESTING

A displacement sensor for a power tool includes: a stator element, having a first conductive pattern, and a rotor element, having a second conductive pattern, for relative movement along a measurement path, wherein the first and second conductive patterns are mutually inductively coupled so that the first conductive pattern receives an excitation signal and the second conductive pattern generates an intermediate signal. The intermediate signal indicates relative displacement between the stator and rotor elements, wherein the excitation signal is a constant amplitude high-frequency signal. A signal processor circuit receives and processes a single phase receive signal corresponding to the intermediate signal to provide an output signal indicating relative displacement between the rotor and stator elements. A phase detector circuit processes the single phase receive signal to detect a phase difference between the receive signal and a reference signal corresponding to the excitation signal to provide the output signal.