On-Display Touch Sensor Stack With Mesh Electrodes for Precise Detection
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Solution Overview
Problem
Current touch sensors, particularly capacitive touch screens, face challenges in accurately detecting the presence and location of touches or proximity within a touch-sensitive area due to limitations in electrode configurations and materials, which can affect capacitance measurement precision and user interaction.
Innovation Solution
The implementation of a capacitive touch sensor with an array of drive and sense electrodes on substrates, utilizing conductive materials like indium tin oxide (ITO) or fine lines of metal, and a mechanical stack comprising layers of optically clear adhesive and dielectric materials, allowing for precise capacitance measurement through mutual- or self-capacitance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electrode configurations and materials are used in capacitive touch screens, then manufacturing is simpler, but capacitance measurement precision deteriorates
Solution Approach 1:
The touch sensor is divided into multiple independent electrode layers (first electrode layer, second electrode layer, third electrode layer) with distinct functions. The first and second electrodes form capacitive nodes for touch detection, while the third electrode provides shielding. This segmentation allows each layer to be optimized for its specific function, improving measurement precision while managing complexity through modular design.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the first and second electrodes, and a shielding electrode (third electrode) is placed as an intermediary between the second electrode and the display. These intermediary elements isolate electrical interference, reduce parasitic capacitance, and improve the signal-to-noise ratio, thereby enhancing capacitance measurement precision.
2Illumination intensity
If transparent conductive materials like ITO are used, then optical transmissivity is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent employs composite material structures where transparent conductive materials (such as ITO) are combined with dielectric materials in layered configurations. This allows the system to maintain high optical transmissivity through the transparent conductive layers while the dielectric layers provide electrical isolation and structural support, enabling manufacturing through established thin-film deposition techniques.
Solution Approach 2:
The electrodes and dielectric layers are implemented as thin films that can be deposited using standard semiconductor manufacturing processes. This thin-film approach maintains optical transparency while enabling precise control of electrical properties, and the flexible layered structure accommodates integration with various display types without requiring complex manufacturing equipment.
3Measurement precision
If multiple electrode layers are added to improve touch detection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The touch sensor is divided into multiple independent electrode layers (first electrode layer, second electrode layer, third electrode layer) with distinct functions. The first and second electrodes form capacitive nodes for touch detection, while the third electrode provides shielding. This segmentation allows each layer to be optimized for its specific function, improving measurement precision while managing complexity through modular design.
Solution Approach 2:
The dielectric layer serves multiple functions simultaneously: it provides electrical isolation between conductive layers, acts as a mechanical support structure, and functions as part of the optical stack. The shielding electrode provides both electrical shielding and structural definition for the touch-sensitive area. This multi-functionality reduces the need for additional dedicated components, managing overall device complexity.
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 configuration enhances the accuracy of touch detection and location determination, enabling effective user interaction by improving capacitance measurement precision and maintaining high optical transmissivity, thus addressing the limitations of existing touch sensors.
Implementation Method 1
When an object touches or comes within proximity of the surface of the capacitive touch screen, a change in capacitance may occur within the touch screen at the location of the touch or proximity
Implementation Method 2
A capacitive touch screen may include an insulator coated with a substantially transparent conductor in a particular pattern
Data Source
AI summary
In one embodiment, an electronic display includes a display stack including one or more layers; and drive or sense electrodes of a touch sensor substantially disposed on one or more of the layers on or within the display stack. The drive or sense electrodes are made of a conductive mesh of conductive material.