Capacitive Contactless Encoder Resists Wear
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Solution Overview
Problem
Mechanical encoders and switches fail due to wear and tear and contact oxidation, especially in outdoor environments, necessitating a more robust design.
Innovation Solution
A contactless rotary encoder based on a finite state machine with a capacitively coupled design, utilizing a mechanical rotary switch with conductive components and an integrated circuit to detect states without direct contact, ensuring reliability and immunity to environmental degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical contact is used in encoders, then the encoder can detect position and motion, but the moving parts experience wear and oxidation leading to failure
Solution Approach 1:
The patent replaces direct mechanical contact with capacitive coupling to detect rotor position. The stator contains conductive segments that form capacitors with corresponding conductive segments on the rotor through a dielectric barrier, eliminating mechanical contact while maintaining detection functionality. This substitution of mechanical contact with electrical field interaction resolves the wear and oxidation problems.
Solution Approach 2:
The patent introduces a dielectric material as an intermediary between the stator and rotor conductive segments. This dielectric barrier prevents direct contact between moving and stationary parts while still allowing capacitive coupling to occur, enabling position detection without mechanical contact. The intermediary protects against wear and oxidation by maintaining physical separation.
2Reliability
If contactless capacitive coupling is used, then wear and oxidation are eliminated, but device complexity increases
Solution Approach 1:
The conductive segments on both stator and rotor serve multiple functions: they form capacitive detectors for position sensing and simultaneously act as signal generators. This multi-functionality reduces the need for separate components, offsetting the added complexity of the contactless design with functional integration.
Solution Approach 2:
The encoder is divided into discrete conductive segments arranged on the stator and rotor, with each segment corresponding to a specific angular position. This segmentation allows for modular construction and simplifies the detection of multiple position states. The segmented structure makes the complex capacitive coupling system manageable and manufacturable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The contactless encoder provides high reliability and durability, resisting wear and oxidation, maintaining performance in harsh outdoor conditions with low power consumption and stable long-term operation.
Implementation Method 1
a first capacitor is formed from the central circular portions of the selector and the plate; a second capacitor is formed when the selector and a prescribed sector pad align or at least partially align
Data Source
AI summary
A contactless encoder is disclosed. The encoder comprises a selector configured to select one of a plurality of states associated with the encoder. The encoder furthermore comprises an integrated circuit comprising a finite state machine configured to detect a currently selected state by the selector and generate an output signal corresponding to the detected currently selected state, wherein the currently selected state is detected based on a capacitive coupling between the selector and a portion of the encoder associated with the currently selected state.