Single-Layer TCO Touch Screen for Uniform Light Transmission
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Solution Overview
Problem
Capacitive touch screens face challenges with multiple light paths and non-uniform light transmission due to multiple layers of conductive material, leading to artifacts and alignment issues in touch screen assemblies.
Innovation Solution
A touch screen design featuring a single layer of optically transmissive conductive material positioned over all display pixels, with sensor elements rotated and skewed to align with pixel edges, reducing parasitic capacitance and eliminating alignment complexities, while using a thin insulative spacer to minimize capacitance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple layers of conductive material are used in the touch screen, then the sensing capability is improved, but light transmission uniformity deteriorates causing artifacts
Solution Approach 1:
The patent extracts and removes redundant layers of conductive material from the touch screen structure. By using only a single layer of transparent conductive oxide (TCO) instead of multiple layers, the invention eliminates the light transmission non-uniformity and artifacts caused by stacked conductive layers while maintaining adequate capacitance sensing capability through optimized electrode geometry and spacing.
2Measurement precision
If multiple layers of conductive material are stacked, then the capacitance sensing is enhanced, but alignment complexity increases
Solution Approach 1:
The invention removes the complex multi-layer conductive structure and replaces it with a single-layer TCO design. This extraction of redundant layers directly reduces alignment complexity between layers while preserving capacitance sensing functionality through improved electrode patterning and spacing optimization.
Solution Approach 2:
The patent merges the functionality of multiple conductive layers into a single integrated TCO layer. By combining the sensing and signaling functions that were previously distributed across multiple layers into one layer, the invention simplifies the overall structure and eliminates alignment issues between separate conductive layers.
3Ease of manufacture
If sensor elements are aligned with pixel columns, then the manufacturing is simplified, but parasitic capacitance increases
Solution Approach 1:
The patent introduces asymmetric positioning of sensor elements relative to the pixel grid. Instead of aligning sensor elements directly with pixel columns (symmetric arrangement), the invention offsets them to specific positions that minimize overlapping conductive areas, thereby reducing parasitic capacitance while maintaining manufacturability through adjusted patterning processes.
Solution Approach 2:
The invention applies local optimization to the sensor element positioning and geometry. By adjusting the local position, shape, and spacing of individual sensor elements or groups of elements, the patent minimizes parasitic capacitance in critical areas while maintaining overall manufacturing simplicity through standardized fabrication processes.
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
This design provides a consistent light path across the entire display, reducing artifacts and alignment issues, and maintains low parasitic capacitance for effective self- or mutual-capacitance sensing.
Implementation Method 1
a single layer of optically transmissive conductive material is positioned over substantially all of the pixels of the display to provide a more consistent light path for the entire display
Implementation Method 2
The capacitance detected by a capacitance sensor changes as a function of the proximity of a conductive object to the sensor
Implementation Method 3
using a thin insulative spacer to minimize capacitance increase
Data Source
AI summary
A touch screen is described. The touch screen is configured to have an array of conductive, optically transmissive sensor elements coupled to sensor circuitry. The sensor elements are disposed over a display to have a single layer of conductive, optically transmissive material positioned over pixels of the display.