3D Touch Knob Conductive Overlap for Bent-Surface Signal Continuity
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Solution Overview
Problem
Current methods for manufacturing three-dimensional touch knobs rely on expensive and unstable extensible transparent conductive films, while traditional metal oxide films are fragile and unsuitable for three-dimensional applications due to signal discontinuity at bent portions.
Innovation Solution
A three-dimensional touch knob design incorporating a transparent conductive metal oxide film touch sensor, an auxiliary conductive unit with high extensibility and low impedance, and an insulative transparent surface coating layer, which together maintain conductivity at bent portions and reduce material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If transparent metal oxide film (such as ITO) is used for the touch sensor, then material cost is reduced and material supply is increased, but the film is fragile and breaks at bent portions causing electric discontinuity
Solution Approach 1:
The patent changes the material parameter from traditional ITO to a zinc oxide-based transparent conductive film with specific compositional ratios ( ZnO:In2O3:SnO2 in ranges of 95-99.9:0.1-2:0.1-4.9 wt%). This compositional modification maintains electrical conductivity while improving mechanical flexibility and preventing breakage at bent portions, thus resolving the contradiction between material availability and signal transmission reliability.
Solution Approach 2:
The patent creates a composite transparent conductive film by combining zinc oxide with indium oxide and tin oxide in specific proportions. This composite material leverages the advantages of each component: zinc oxide provides mechanical flexibility and cost-effectiveness, while indium oxide and tin oxide contribute to electrical conductivity. The composite structure prevents the film from breaking at bent portions while maintaining low resistance, resolving the contradiction between material supply and signal continuity.
2Reliability
If extensible transparent conductive film is used for the touch sensor, then the film can be applied to three-dimensional surfaces without breaking, but the material is more expensive and has less sources of material supply
Solution Approach 1:
The patent modifies the compositional parameters of the transparent conductive film by using zinc oxide as the base material with specific ratios of indium oxide and tin oxide additives. This parameter change enables the film to achieve both extensibility for three-dimensional surfaces and adequate material supply from zinc oxide sources, while maintaining cost-effectiveness and signal transmission reliability.
3Shape
If extensible transparent conductive film is used for the touch sensor, then the film can be applied to three-dimensional surfaces, but mass production is too unstable to satisfy market demand
Solution Approach 1:
The patent optimizes the compositional parameters of the transparent conductive film (ZnO:In2O3:SnO2 ratios) to achieve a balance between extensibility for three-dimensional surfaces and manufacturing stability. The specific compositional range provides consistent material properties that enable stable mass production while maintaining the ability to cover three-dimensional surfaces effectively.
Data Source
AI summary
A touch knob includes a knob shell having a three-dimensional contour with a curved joint surface; an ITO touch sensor disposed on the knob shell; an auxiliary conductive unit with extensibility, connected on the touch sensor to form an overlapping area covering the joint surface, and the auxiliary conductive unit in the overlapping area having a conductive pattern corresponding to the touch sensor; and a surface coating layer having a three-dimensional contour corresponding to the knob shell and attached on both the touch sensor and the auxiliary conductive unit. An opaque mask surface is provided on an inner side of the surface coating layer. The mask surface cloaks the overlapping area.