In-Cell Touch Sensor Line Arrangement for Display Panel
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Solution Overview
Problem
In display devices with embedded touch sensors in a pixel array, the integration of sensor interconnection lines can lead to color deterioration and bright point defects due to parasitic capacitance and alignment layer damage from spacers.
Innovation Solution
A display device with a touch sensing unit that time-divides the frame period into display driving and touch sensor driving periods, with sensor interconnection lines arranged to avoid spacers and ensure equal sub-pixel distribution around them, minimizing parasitic capacitance effects and alignment layer damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensor interconnection lines are embedded in the pixel array, then the touch sensor can be integrated without increasing display panel thickness, but color deterioration occurs due to parasitic capacitance coupling with pixel electrodes and signal lines
Solution Approach 1:
The frame period is divided into distinct display driving period and touch sensor driving period, allowing separate optimization of each function without interference. This temporal segmentation eliminates parasitic capacitance effects on color display by ensuring sensor lines are inactive during pixel driving.
Solution Approach 2:
The sensor interconnection lines operate periodically during dedicated touch sensing intervals rather than continuously. This periodic activation reduces parasitic capacitance coupling with pixel electrodes during critical display periods, preventing color deterioration while maintaining touch functionality.
2Stability of the object's composition
If spacers are provided on sensor interconnection lines to maintain cell gap, then the liquid crystal layer spacing is maintained, but the alignment layer is raised and damaged by friction with spacers causing bright point defects
Solution Approach 1:
Spacers are extracted from locations where they would contact the alignment layer and instead placed only on data lines or in regions away from the alignment layer. This removes the harmful friction effect while preserving the cell gap maintenance function in critical areas.
Solution Approach 2:
The patent introduces a protective structure or modifies the spacer configuration to act as an intermediary that prevents direct contact between spacers and the alignment layer, thereby eliminating friction-induced damage while maintaining structural support.
3Device complexity
If sensor interconnection lines are embedded in pixel array, then in-cell touch sensor is achieved, but parasitic capacitance causes brightness changes in adjacent sub-pixels
Solution Approach 1:
The operating cycle is segmented into display period and touch sensing period, ensuring sensor interconnection lines are inactive during pixel voltage application. This temporal separation eliminates parasitic capacitance-induced brightness variations while maintaining in-cell integration.
Solution Approach 2:
The sensor interconnection lines dynamically switch between active and inactive states based on the operating period. During display periods, they remain inactive to prevent parasitic capacitance effects on sub-pixel brightness, while activating only during dedicated touch sensing intervals.
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
Prevents color deterioration and alignment layer damage, maintaining image quality by optimizing sensor interconnection line arrangements and ensuring equal brightness across sub-pixels.
Implementation Method 1
a touch sensor driver for applying a touch driving voltage for sensing touch to the plurality of touch electrodes via the plurality of sensor interconnection lines during the touch sensor driving period of the frame period
Implementation Method 2
the integration of sensor interconnection lines can lead to color deterioration and bright point defects due to parasitic capacitance
Data Source
AI summary
A touch sensing device comprises a display panel including a plurality of data lines and a plurality of sensor interconnection lines, the plurality of data lines connected to a plurality of pixels of the display panel, and the plurality of sensor interconnection lines connected to a plurality of touch electrodes of the display panel, each pixel including a plurality of sub-pixels that each display a distinct color. A pattern of sub-pixels is arranged in the display panel such that a same number of sub-pixels for each distinct color is arranged adjacent to a first side and adjacent to a second side of one or more of the plurality of sensor interconnection lines, each of the sub-pixels for each distinct color being adjacent to either the first side or the second side of a corresponding one of the sensor interconnection lines.