PCAP Touchscreen Electrode Layout for Optical Uniformity
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Solution Overview
Problem
Commercial touchscreens often exhibit optical discontinuities due to variations in the placement and proximity of transparent conductive electrodes, making them difficult to manufacture in large quantities while maintaining both optical and electronic performance.
Innovation Solution
The use of floating transparent conductive islands between electrode layers in touchscreen designs, which minimizes optical discontinuities by filling gaps and ensuring a uniform appearance, and edge correction techniques to adjust mutual capacitances, allowing for uniform electrostatic fields and efficient touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transparent conductive electrodes are placed to form electrode patterns, then touch detection function is achieved, but optical discontinuities occur making the screen appearance non-uniform
Solution Approach 1:
A transparent conductive film is introduced as an intermediary layer between the electrode patterns and the display. This film fills the gaps between electrode patterns and provides a continuous optical surface, eliminating the non-uniform appearance while preserving the touch detection function of the electrode patterns below.
Solution Approach 2:
The transparent conductive film is designed with optical properties that allow light to pass through uniformly, creating an optically continuous surface that masks the discontinuous electrode patterns beneath. The film's transparency and uniformity compensate for the gaps in the electrode structure.
2Measurement precision
If electrode patterns are made more dense to improve touch sensitivity, then touch detection precision improves, but optical discontinuities become more visible
Solution Approach 1:
The transparent conductive film serves as a mediating layer that allows the electrode patterns to be denser for improved touch sensitivity while the film itself provides the uniform optical surface. The film decouples the optical appearance from the electrode density, allowing optimization of touch detection without compromising visual uniformity.
3Illumination intensity
If multiple layers of transparent conductive material are used to fill gaps, then optical uniformity improves, but device complexity increases
Solution Approach 1:
Instead of adding multiple complex layers to fill gaps, the invention extracts the optical uniformity function into a single transparent conductive film layer. This film performs the gap-filling function alone, eliminating the need for multiple layered structures and simplifying the overall device architecture.
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 solution effectively reduces the perception of optical discontinuities and enhances touch sensitivity by maintaining uniform mutual capacitance values, compatible with screen printing processes for cost-effective large-scale production.
Implementation Method 1
The touchscreen system detects a presence and/or a location of a touch from an operator... edge correction techniques adjust mutual capacitances to ensure consistent electrostatic fields
Implementation Method 2
edge correction techniques adjust mutual capacitances to ensure consistent electrostatic fields, thereby improving both the visual and operational aspects of the touchscreen
Data Source
AI summary
Various configurations and arrangements for touchscreens are disclosed to accommodate for one or more optical discontinuities that can be present within these touchscreens. When the one or more optical discontinuities are present, these configurations and arrangements of the touchscreens present a single layer of transparent conductive material that can be difficult to perceive by a human eye when viewing the touchscreens. Additionally, various edge correction techniques are disclosed to adjust mutual capacitances along a perimeter of the touchscreens. These edge correction techniques adjust mutual capacitances such that the values of the mutual capacitances are substantially uniform throughout.