Touch Panel High-Low Resistance Segmentation for Static Discharge
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Solution Overview
Problem
In transverse-electric-field in-cell liquid crystal panels, static electricity can disturb the display by charging the second substrate and causing misalignment of liquid crystal molecules, and existing solutions require a conductive film with specific time constants that complicate touch detection sensitivity and static discharge.
Innovation Solution
A touch panel design featuring a first substrate with touch sensor electrodes and a second substrate with a liquid crystal layer and a color filter, where a high-resistance portion is disposed over the touch sensor electrodes and a low-resistance portion is connected to the high-resistance portion, allowing static charges to be quickly discharged through a conductive material to the reference potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive film with high time constant is used to cover the liquid crystal display element, then static electricity discharge is improved, but touch detection sensitivity deteriorates due to capacitance interference
Solution Approach 1:
The conductive film is segmented into two distinct regions: a high-resistance portion positioned over the touch sensor electrodes and a low-resistance portion positioned in the peripheral frame region. This segmentation allows each region to perform its specialized function independently, resolving the contradiction between static discharge capability and touch detection sensitivity.
Solution Approach 2:
Different resistance characteristics are assigned to different spatial locations of the conductive film. The high-resistance portion in the display region minimizes capacitance interference with touch electrodes, while the low-resistance portion in the frame region provides effective static electricity discharge paths. This local differentiation of properties resolves the technical contradiction.
2Object-affected harmful factors
If a conductive film covers the entire surface including touch electrodes, then static electricity protection is improved, but device complexity increases due to time constant requirements
Solution Approach 1:
The conductive film is divided into functionally distinct segments (high-resistance and low-resistance portions) with clearly defined spatial boundaries. This segmentation simplifies the overall design by allowing each segment to be optimized independently for its specific function, reducing the complexity of achieving both protection and detection goals simultaneously.
Solution Approach 2:
The conductive film exhibits spatially varying resistance properties, with high resistance in the display region and low resistance in the frame region. This local quality differentiation enables the film to provide both static electricity protection and touch detection functionality without requiring complex additional components or control mechanisms.
3Reliability
If the second substrate is charged with static electricity, then electrostatic protection is compromised, but liquid crystal alignment is disturbed causing display disturbances
Solution Approach 1:
The high-resistance portion of the conductive film acts as an intermediary layer between the touch sensor electrodes and the second substrate. It provides a controlled path for static electricity dissipation while maintaining electrical isolation that prevents direct interference with liquid crystal alignment, thus protecting both the electrostatic balance and display stability.
Solution Approach 2:
The resistance parameter of the conductive film is strategically varied across different regions. The high-resistance portion in the display region limits current flow to prevent liquid crystal disruption, while the low-resistance portion in the frame region facilitates static charge dissipation, thereby maintaining both electrostatic protection and display stability.
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 touch detection sensitivity while effectively suppressing static electricity-induced display disturbances, even in touch panels with limited or irregular shapes, without the need for a conductive film covering the entire surface.
Implementation Method 1
a high-resistance portion that is disposed over the touch sensor electrode, a low-resistance portion that is disposed on a periphery surrounding the high-resistance portion, that has resistance lower than resistance of the high-resistance portion
Implementation Method 2
a touch sensor electrode that outputs a detection signal based on change in capacitance
Data Source
AI summary
A touch panel includes a first substrate including a touch sensor electrode outputting a detection signal based on change in capacitance, and a pixel electrode, a second substrate disposed with a liquid crystal layer interposed between the second substrate and the first substrate and including a color filter, a high-resistance portion disposed over the touch sensor electrode, on an upper surface of the second substrate, a low-resistance portion disposed on a periphery surrounding the high-resistance portion on the upper surface of the second substrate, having resistance lower than resistance of the high-resistance portion, and connected to the high-resistance portion, and a conductive material connecting the low-resistance portion to a reference potential. The upper surface of the second substrate has a display region over the pixel electrode and a frame region on an outer side thereof. The touch sensor electrode is disposed beyond the display region to the frame region.