US Patent No. 9,933,283

ROBUST ROTARY ENCODER FOR POWER TOOL


Patent No. 9,933,283
Issue Date April 03, 2018
Title Robust Rotary Encoder For Power Tool
Inventorship
Assignee ATLAS COPCO INDUSTRIAL TECHNIQUE AB, Stockholm (SE)

Claim of US Patent No. 9,933,283

1. A displacement sensor for a power tool, the displacement sensor comprising:a stator element and a rotor element configured for relative movement along a measurement path, said stator element having a first conductive pattern and said rotor element having a second conductive pattern, the first conductive pattern and the second conductive pattern being mutually inductively coupled, the first conductive pattern being configured to receive an excitation signal, the second conductive pattern being configured to generate an intermediate signal therein caused due to mutual induction between the first conductive pattern and the second conductive pattern, said intermediate signal being indicative of the relative displacement between the stator element and the rotor element, and the excitation signal being a high-frequency excitation signal having substantially constant amplitude, and
a single phase signal processor circuit configured to receive and process a single phase receive signal, corresponding to the intermediate signal received at the stator element, so as to provide an output signal indicative of the relative displacement between the rotor element and the stator element, the single phase signal processor circuit comprising a phase detector circuit configured to process the single phase receive signal in order to detect a phase difference between the single phase receive signal and a reference signal corresponding to the excitation signal so as to provide said output signal.