Rotary Encoder Insulator Wear Reduction via Composite Fillers

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Solution Overview

Problem

Conventional rotary encoders face issues with wear of the insulating substrate due to its lower hardness compared to the metallic slider, leading to substrate wear and potential electrical characteristic changes.

Innovation Solution

Incorporating spherical silica and a fluororesin filler, such as polytetrafluoroethylene, into the insulating material to enhance the hardness and reduce friction, thereby minimizing wear on both the insulating substrate and the slider.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulating substrate is constituted of a resin, then the insulating substrate provides good electrical insulation, but the hardness of the insulating substrate becomes lower than hardness of the slider, causing wear of the insulating substrate

Engineering Contradiction:

Improveelectrical insulationVSAvoidhardness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The insulating substrate uses a composite material consisting of a resin base material combined with inorganic filler particles (such as silica, alumina, or titania). This composite structure provides both the electrical insulation properties of the resin and the enhanced hardness and wear resistance of the inorganic filler, resolving the contradiction between softness (for insulation) and hardness (for wear resistance).

Inventive Principle:

Principle #40Composite materials

2Reliability

If the insulating substrate is made softer for better insulation, then electrical insulation is improved, but wear of the insulating substrate increases when the slider slides on it

Engineering Contradiction:

Improveelectrical insulationVSAvoidwear of insulating substrate

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

By incorporating inorganic filler particles into the resin matrix, the insulating substrate achieves a balance where the resin provides electrical insulation while the inorganic filler minimizes wear. The filler particles are distributed throughout the resin to create a composite that resists wear from slider contact while maintaining insulating properties.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the physical and chemical parameters of the insulating substrate by controlling the type, size, and concentration of inorganic filler particles. By optimizing these parameters, the substrate achieves sufficient hardness to resist wear while maintaining the electrical insulation characteristics required for encoder operation.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a metallic slider is used for detection, then detection precision is improved, but the slider causes wear to the softer insulating substrate during sliding contact

Engineering Contradiction:

Improvedetection precisionVSAvoidwear of insulating substrate

Core Design Contradiction:

Measurement precisionVSLoss of substance

Solution Approach 1:

The insulating substrate is designed as a composite material with inorganic filler particles embedded in a resin matrix. This composite structure enables the substrate to withstand the sliding contact of metallic sliders without excessive wear, while the slider maintains its metallic properties for accurate electrical detection of the encoder pattern.

Inventive Principle:

Principle #40Composite materials

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 use of spherical silica and fluororesin filler effectively reduces wear on the insulating substrate and slider, improving sliding performance and extending the service life of the rotary encoder while maintaining reliable contact with the resistor portions.

Implementation Method 1

wear of the insulator portion is able to be reduced due to high hardness of the spherical silica included in the insulator portion

Methodology Applied

Scientific EffectHardness enhancement through spherical silica incorporation:

Implementation Method 2

sliding of the slider on one surface on which the slider of the insulator portion slides is good and a friction coefficient is reduced by the fluororesin filler of the insulator portion

Methodology Applied

Scientific EffectFriction reduction through fluororesin filler:

Data Source

PatentUS10832878B2Rotary encoder

Publication Date: 2020.11.10 MURATA MFG CO LTD

AI summary

A rotary encoder includes a shaft and an encoder mechanism that holds the shaft in a rotatably inserted state and detects a rotation direction and a rotation angle of the shaft. The encoder mechanism includes a substrate that rotatably holds the shaft, an insulator portion and a resistor portion provided on one surface of the substrate and alternately provided in the rotation direction of the shaft, a rotor attached to the shaft so as to be integrally rotatable with the shaft, and a slider that is attached to the rotor and alternately slidably contacts the insulator portion and the resistor portion by rotation of the shaft. The insulator portion includes a base material made of a resin, spherical silica, and a fluororesin filler.