Inductive Redundant Touch Switch Without Fixed Stroke

Solution Overview

Problem

Existing duplicated switches require a fixed stroke, limiting their application in touch-sensitive devices like keyboards and operation boards, where they restrict operability and design flexibility.

Innovation Solution

A duplicated touch switch utilizing induction-type proximity sensors with LC oscillation circuits, which detect changes in distance to metal pieces, allowing for touch detection without a fixed stroke and enabling redundancy in switch systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a duplicated switch uses a fixed stroke structure, then reliability and safety are improved through redundancy, but operability and design flexibility are restricted

Engineering Contradiction:

Improveswitch reliabilityVSAvoidoperability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the traditional mechanical stroke-based switch system with a touch switch system using induction-type proximity sensors. The sensor detects the approach of a metal piece (fingertip) through electromagnetic induction, eliminating the need for mechanical stroke and contact pressure. This substitution maintains reliability through redundant sensor systems while dramatically improving operability and design flexibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the detection parameter from mechanical displacement (fixed stroke) to electromagnetic induction field changes. The proximity sensor detects changes in the electromagnetic field caused by the approach of conductive objects, allowing touch detection without fixed mechanical stroke. This parameter change enables flexible design while maintaining reliable redundant operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a duplicated switch uses a fixed stroke structure, then reliability and safety are improved through redundancy, but design flexibility is restricted

Engineering Contradiction:

Improveswitch reliabilityVSAvoiddesign flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the traditional mechanical stroke-based switch system with a touch switch system using induction-type proximity sensors. The sensor detects the approach of a metal piece (fingertip) through electromagnetic induction, eliminating the need for mechanical stroke and contact pressure. This substitution maintains reliability through redundant sensor systems while dramatically improving operability and design flexibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the detection parameter from mechanical displacement (fixed stroke) to electromagnetic induction field changes. The proximity sensor detects changes in the electromagnetic field caused by the approach of conductive objects, allowing touch detection without fixed mechanical stroke. This parameter change enables flexible design while maintaining reliable redundant operation.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a duplicated switch uses traditional contact structure, then reliability is achieved through redundant contacts, but the device area increases

Engineering Contradiction:

Improveswitch reliabilityVSAvoidswitch area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the functions of multiple redundant switches into a single integrated touch input section. The proximity sensors and metal piece are positioned such that a single touch action can simultaneously activate multiple redundant detection points. This merging reduces the overall device area while maintaining reliability through redundant sensor systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention transitions from a two-dimensional planar arrangement of separate switch contacts to a three-dimensional configuration where the metal piece moves through space toward the sensor. The detection occurs in the vertical dimension (distance change) rather than requiring lateral separation of multiple contacts, thereby reducing the footprint area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

Improves operability and design flexibility of touch-sensitive devices by ensuring reliable operation even if one switch system fails, while reducing the area required for the touch input section.

Implementation Method 1

an induction-type proximity sensor 10 which has an LC oscillation circuit 12, 13 and senses a change in an oscillation state of the LC oscillation circuit when a metal piece 30 is brought into proximity to, but not in contact with, the LC oscillation circuit

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10439609B2Redundant touch switch using induction proximity sensors

Publication Date: 2019.10.08 FANUC LTD

AI summary

A touch switch includes a touch input section, a metal piece provided to the touch input section at a surface thereof, and at least two induction-type proximity sensors so provided as to face the metal piece. The induction-type proximity sensors are arranged in parallel to each other and each have an LC oscillation circuit that output signals that changes in accordance with the distance to the metal piece. A duplicated touch switch that requires no stroke and achieves switch duplication is thus provided.