Touch Sensor Electrodes with Blackened Side Surfaces
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Solution Overview
Problem
Capacitive touch sensors with metal electrodes face challenges in minimizing visibility and resistance while maintaining high sensitivity and light transmission, especially as they increase in size, due to the reflective nature of metal and the need for smaller wire widths to reduce visibility.
Innovation Solution
A touch sensor substrate with electrodes featuring a blackened layer on their side surfaces and at least one of their top or bottom surfaces, achieved through black sulfide or black substitution treatments, which suppresses reflective luster and maintains low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal electrodes are used to maintain low resistance, then electrical conductivity is improved, but visibility and light transmission are worsened due to reflective luster
Solution Approach 1:
The patent applies a black colored coating layer on the metal electrode to change its appearance from reflective to non-reflective. This color change suppresses the reflective luster of the metal electrode, reducing visibility while maintaining the underlying metal's electrical conductivity. The black coating absorbs light rather than reflecting it, thereby improving light transmission characteristics.
Solution Approach 2:
The patent creates a composite structure combining metal material (for conductivity) with a black coating material (for light absorption). This composite approach allows the electrode to simultaneously achieve low electrical resistance through the metal core while minimizing visibility through the light-absorbing black coating layer on the surface.
2Object-affected harmful factors
If wire width is reduced to minimize visibility, then aesthetic appearance is improved, but electrical resistance increases and sensitivity decreases
Solution Approach 1:
By applying a black coating to the electrode surface, the patent allows the use of sufficiently wide wire dimensions to maintain low electrical resistance while the black coloration minimizes visual perception of the electrode width. The coating makes the electrode less visible regardless of its actual physical dimensions.
Solution Approach 2:
The patent changes the optical parameters of the electrode surface through coating application, transforming it from a reflective surface to a light-absorbing surface. This parameter change in optical properties allows the electrode to be less visible while maintaining adequate physical dimensions for low electrical resistance.
3Illumination intensity
If transparent conductive material is used to improve light transmission, then transparency is improved, but electrical resistance increases and sensitivity decreases
Solution Approach 1:
The patent employs a composite electrode structure with a metal core providing low electrical resistance and a black coating layer providing light absorption. This composite design eliminates the need to choose between transparent materials (which have high resistance) and metal materials (which block light), as the black coating actually improves light transmission by reducing reflection.
4Object-affected harmful factors
If black coating is applied to reduce visibility, then aesthetic appearance is improved, but electrical resistance may increase
Solution Approach 1:
The patent specifies that the black coating should have a surface resistivity of less than 10000 Ω/square, and preferably less than 1000 Ω/square. This controlled electrical property of the coating ensures that while visibility is reduced through black coloration, the increase in electrical resistance remains within acceptable limits for touch sensor operation.
Solution Approach 2:
The patent carefully controls the electrical resistance parameter of the black coating layer, specifying that its surface resistivity should be less than 10000 Ω/square. This parameter control allows the coating to provide sufficient light absorption and visibility reduction while maintaining adequate electrical conductivity for touch sensor functionality.
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 blackened layer reduces the visibility and resistance of the electrodes, ensuring minimal impact on sensitivity and light transmission, while maintaining a surface resistivity of less than 1 Ω/square and reflectivity below 20% in visible wavelengths.
Implementation Method 1
achieved through black sulfide or black substitution treatments
Implementation Method 2
achieved through black sulfide or black substitution treatments
Data Source
AI summary
A touch sensor substrate including a base material having a first surface, and electrodes each having a bottom surface positioned on the first surface, a top surface opposite to the bottom surface, and side surfaces connecting the bottom and top surfaces, each of the electrodes having a blackened layer formed on the side surfaces and at least one of the bottom and top surfaces. The blackened layer has a surface resistivity of less than 1 Ω/square.