Segmented Common Electrodes for Touch Sensor Integrated Display
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Solution Overview
Problem
Conventional touch screens with integrated touch sensors in display panels face issues with undesired parasitic capacitance and cross-talk, leading to unsatisfactory display quality, particularly in IPS and FFS mode LCDs, where pixel and common electrodes are on the same side.
Innovation Solution
The configuration includes segmented common electrodes forming touch driving and sensing channels, with separate metal layers for pixel and circuit TFTs, and strategically placed touch signal lines to reduce capacitance coupling and cross-talk, enhancing touch sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If touch sensor is integrated within the display panel using existing display components, then device complexity is reduced and thickness is decreased, but parasitic capacitance increases leading to reduced measurement precision
Solution Approach 1:
The common electrode is divided into multiple common electrode blocks that can be selectively electrically linked to form touch driving channels. This segmentation allows independent control of different regions, reducing parasitic capacitance interference in specific sensing areas while maintaining the integrated structure benefits.
Solution Approach 2:
The touch sensing function is extracted from the traditional separate touch panel and integrated into the display panel's common electrode structure. By reconfiguring existing display components to serve dual purposes, the patent eliminates the need for a separate touch panel while maintaining touch sensing capability.
2Ease of manufacture
If pixel electrode and common electrode are provided on the same side of liquid crystal layer for IPS/FFS mode, then ease of manufacture is improved, but cross-talk increases reducing measurement precision
Solution Approach 1:
The common electrode is segmented into multiple blocks that can be selectively activated. This allows the patent to maintain the simple IPS/FFS manufacturing structure while reducing cross-talk by deactivating certain common electrode blocks during touch sensing operations, thereby isolating sensing regions from display regions.
Solution Approach 2:
The patent employs periodic switching between display mode and touch sensing mode by selectively linking common electrode blocks. During touch sensing, specific common electrode blocks are activated while others are deactivated, creating periodic action that reduces continuous cross-talk interference while maintaining manufacturing simplicity.
3Measurement precision
If separate capacitive touch sensor panel is overlaid on display, then touch sensing accuracy is maintained, but device weight and thickness increase
Solution Approach 1:
The patent merges the touch sensor function with the display panel by configuring the common electrode to serve both display and touch sensing purposes. This integration eliminates the separate touch panel overlay, reducing device weight and thickness while maintaining touch sensing accuracy through selective electrode block activation.
Solution Approach 2:
The common electrode is designed to perform multiple functions: displaying images during normal operation and sensing touch inputs when configured as touch driving channels. This multi-functionality eliminates the need for separate touch panel components, reducing overall device weight and thickness.
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 improves touch sensing accuracy and reduces unwanted capacitance coupling, resulting in better display quality and touch input recognition, even at the edges of the panel.
Implementation Method 1
Touch input is recognized by change in capacitance when an object, such as a user's finger, touches the touch panel
Data Source
AI summary
A touch sensor integrated display device includes a plurality of common electrode blocks that defines a plurality of touch driving channels and a plurality of touch sensing channels. The touch driving channel is formed of a group of common electrode blocks electrically linked via a touch signal line placed under the layer of the common electrode blocks. The source/drain of the circuit TFTs provided in the non-display area is formed of the same metal layer of the touch signal line. The source/drain of the pixel TFTs provided in the display area is formed of a metal layer different from the metal layer of the touch signal line.