Touch Sensor Integrated Display Device with Planarization Layers
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Solution Overview
Problem
Conventional touch sensor integration in display devices leads to thickness and weight increases due to separate touch panels, and compromises in display quality when integrated within display pixels, particularly in IPS and FFS mode LCDs where electrodes control liquid crystal orientation.
Innovation Solution
The integration of touch sensor components within the display device's pixel structure, utilizing a configuration with storage capacitors and electrodes that operate both for display and touch sensing, where common electrode blocks are shared among pixels, and common signal lines are routed parallel to data lines to minimize thickness and prevent fringe field generation, allowing for efficient touch recognition without compromising display functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If touch sensor components are integrated within display pixels, then device thickness and weight are reduced, but display quality is compromised
Solution Approach 1:
The display panel is divided into distinct functional regions: pixel regions for display and touch sensor regions for touch sensing. This segmentation allows each region to be optimized for its specific function without compromising the other, enabling both high display quality and effective touch sensing in the same device
Solution Approach 2:
The touch sensor electrodes are arranged in multiple layers at different positions within the display panel structure. By utilizing the vertical dimension and creating overlapping electrode patterns in different layers, the patent achieves effective touch sensing without adding significant thickness or compromising display quality
2Area of stationary object
If common signal lines are routed across active area, then bezel size is reduced, but RC delays increase
Solution Approach 1:
The common signal lines are segmented into multiple sections, with each section serving a specific group of pixels. This segmentation allows for optimized routing paths that minimize total line length and reduce RC delays while still achieving compact bezel dimensions
Solution Approach 2:
Signal distribution is achieved through intermediary structures such as common electrode blocks that can be shared among multiple pixels. This intermediary approach reduces the need for extensive individual signal lines across the active area, thereby reducing RC delays while maintaining compact bezel size
3Ease of operation
If electrodes are provided on one side of liquid crystal layer for IPS/FFS mode, then liquid crystal orientation is controlled, but touch sensing accuracy at edges deteriorates
Solution Approach 1:
Additional touch sensor electrodes are introduced in layers positioned above and below the liquid crystal layer, creating a multi-layer electrode structure. This three-dimensional electrode arrangement ensures that touch sensing capability is maintained uniformly across the entire display area, including edges, without interfering with the liquid crystal orientation control mechanism
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 enables touch-sensing functionality with reduced bezel size, minimal RC delays, and no light leakage, maintaining display quality while reducing the device's thickness and weight, and improving touch-sensing accuracy at the edges.
Implementation Method 1
TO withstand the processes involved in fabricating the TFTs, the lower planarization layer may have higher thermal stability than the upper planarization layer
Implementation Method 2
a lower planarization layer is interposed between the common signal lines and the layer of TFTs. Also, an upper planarization layer is interposed between the layer of TFTs and the common electrode blocks
Implementation Method 3
changes in mutual capacitances generated between the touch-driving blocks and the touch-sensing blocks can be measured to identify user inputs
Data Source
AI summary
A touch sensor integrated display device includes a plurality of common electrode blocks serving as touch-sensing regions and/or touch-driving regions. Conductive lines connected to the common electrode blocks are placed under the common electrode blocks and the pixel electrodes of the pixels, and they are routed across the active area, directly toward an inactive area where drive-integrated circuits are located. The conductive lines are positioned under one or more planarization layers, and are connected to the corresponding common electrode blocks via one or more contact holes.