TN Display Panel with Through-Substrate Touch Sensing
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Solution Overview
Problem
Existing liquid crystal display panels with touch control functions in twisted nematic (TN) mode face challenges as the capacitance change incurred by touch is shielded by the liquid crystal capacitance generated during display, making touch sensing structures inapplicable.
Innovation Solution
A display panel design with electrodes on two opposite sides of a liquid crystal layer, utilizing spacers and bridge pads to enable reliable touch control by ensuring the capacitance change is not shielded during display, allowing for both liquid crystal driving and touch sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a touch sensing structure is used in TN mode display panels, then touch control function is enabled, but the capacitance change is shielded by liquid crystal capacitance making sensing ineffective
Solution Approach 1:
The patent transitions from in-plane capacitance sensing to through-substrate capacitance sensing by placing electrodes on opposite sides of the liquid crystal layer. This dimensional change allows the sensing electric field to penetrate through the liquid crystal layer rather than being confined within the same plane, thereby avoiding the shielding effect of liquid crystal capacitance and enabling effective touch detection in TN mode displays.
Solution Approach 2:
The patent introduces a transparent conductive oxide layer as an intermediary sensing electrode between the liquid crystal layer and the touch surface. This intermediary layer enables capacitance change detection without directly interfering with the liquid crystal driving electrodes, allowing touch sensing to function effectively while maintaining display performance in TN mode panels.
2Productivity
If electrodes are disposed on two opposite sides of liquid crystal layer for display driving, then liquid crystal driving is effective, but touch sensing becomes difficult due to capacitance shielding
Solution Approach 1:
The patent segments the electrode system into distinct functional layers: display driving electrodes on the first substrate and touch sensing electrodes on the second substrate. This segmentation allows each electrode system to perform its specific function independently without interfering with the other, enabling both effective liquid crystal display driving and reliable touch control functionality in TN mode panels.
Solution Approach 2:
The patent creates a multi-functional electrode structure where the first substrate electrodes serve display driving functions while the second substrate electrodes provide touch sensing capabilities. This universal design enables the display panel to simultaneously achieve effective liquid crystal driving and reliable touch control, making the panel adaptable to both display and interaction requirements.
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
Enables reliable touch control functionality while maintaining effective liquid crystal display performance by using spacers and bridge pads to connect electrodes, ensuring capacitance changes are not obstructed by liquid crystal capacitance.
Implementation Method 1
The liquid crystal layer is disposed between the first substrate and the second substrate... perform liquid crystal driving in a twisted nematic (TN) mode
Implementation Method 2
the location is detected by sensing the capacitance change between each set of pixel electrode and common electrode on the same substrate
Data Source
AI summary
A display panel, including a first substrate, a second substrate, a liquid crystal layer, multiple data lines, multiple scan lines, multiple touch signal lines, multiple pixel structures, multiple bridge pads, multiple electrode patterns, and multiple first spacers. The liquid crystal layer is disposed between the first substrate and the second substrate. The bridge pads are disposed on the first substrate and are electrically connected to the touch signal lines respectively. The electrode patterns are respectively arranged on the second substrate at intervals along a first direction and a second direction, and overlap the pixel electrodes of the pixel structures. The first spacers are disposed on the second substrate and respectively abut on the bridge pads along a stacking direction of the first substrate and the second substrate. Each of the electrode patterns covers one of the first spacers to be electrically connected to one of the bridge pads.