Flexible Input Device Electrode Bending Reliability
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Solution Overview
Problem
ITO and metal electrodes used in translucent input devices tend to crack or experience conduction failure when bent, making it difficult to maintain translucency and conductivity, especially at bent portions.
Innovation Solution
The use of a flexible conductive member with a covering material, such as a resin-based material, and an optical adhesive layer to mitigate tensile stress and cohesion forces, allowing the electrodes to bend with the base material without compromising translucency and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO or metal is used as translucent electrode or lead wire, then translucency and conductivity are achieved, but cracks or conduction failure occur when bent
Solution Approach 1:
The patent uses a composite structure consisting of a flexible conductive member (such as conductive polymer or metal nanowire) covered by a covering material (resin-based material). This composite structure combines the flexibility of the flexible conductive member with the protective properties of the covering material, allowing the electrode to bend without cracking while maintaining translucency and conductivity.
2Strength
If easy-to-bend material such as conductive polymer or metal nanowire is used, then flexibility is improved, but translucency and conductivity are lowered
Solution Approach 1:
The patent employs a composite material system where the flexible conductive member provides flexibility while the covering material maintains translucency and protects conductivity. This composite approach allows the use of flexible materials like conductive polymer or metal nanowire without sacrificing the required optical and electrical properties, as the covering material compensates for any degradation.
3Illumination intensity
If wire thickness is reduced to improve translucency, then translucency is improved, but wire becomes more susceptible to breakage when bent
Solution Approach 1:
The patent uses a composite structure where the thin flexible conductive member (optimized for translucency) is protected by the covering material. The covering material acts as a protective layer that prevents the thin wire from breaking during bending, allowing the wire to be made thinner for improved translucency without compromising reliability.
Solution Approach 2:
The covering material serves as a protective layer applied beforehand to cushion and protect the thin flexible conductive member from mechanical stress during bending. This prior protection prevents cracks in the thin wire while maintaining the desired translucency.
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
Enables the bending of wires with the base material while maintaining translucency and conductivity, reducing the likelihood of cracks and conduction failures at bent portions.
Implementation Method 1
a cohesion force is generated in the covering material according to this external force. This cohesion force is exerted so as to mitigate the tensile stress generated in the flexible conductive member
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
As an input device for which a structure in the vicinity of a bent portion was improved so that wires can be bent together with a base material without impairing translucency and conductivity, an input device 1 is provided that has: a base material 11 having translucency and flexibility; a plurality of first electrode parts 21 having translucency, the plurality of first electrode parts 21 being arranged in a sensing region OR on the base material 11 in a first direction; a plurality of second electrode parts 31 having translucency, the plurality of second electrode parts 31 being arranged in the sensing region OR on the base material 11 in a second direction crossing the first direction; and a plurality of lead wires 14 that are electrically continuous to the plurality of first electrode parts 21 and the plurality of second electrode parts 31, the plurality of lead wires 14 extending from the sensing region OR on the base material 11 to a peripheral region SR outside the sensing region OR. A bent portion BR is provided in the peripheral region SR on the base material 11. The lead wire 14 has a flexible laminated body 15 provided on the bent portion BR. A covering material 51 is included that is provided so as to cover at least part of the flexible laminated body 15 provided on the bent portion BR.