Display Device Common Electrode Touch Sensing Aperture Ratio
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Solution Overview
Problem
The integration of both capacitive and photo touch sensors in touch screen in-cell type display devices leads to a decrease in aperture ratio, compromising touch sensitivity and display quality.
Innovation Solution
A display device design that incorporates a common electrode for both display driving and touch sensing, with photo touch sensors connected to sensing lines adjacent to the common electrodes, allowing for efficient touch detection without reducing the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both photo touch sensor and capacitive touch sensor are integrated in the touch screen in-cell type display device, then touch sensitivity is improved, but aperture ratio decreases
Solution Approach 1:
The display device divides the touch sensing function into two separate sensor systems: photo touch sensors that detect light changes and capacitive touch sensors that detect capacitance changes. This segmentation allows each sensor type to be optimized for its specific function while sharing the common electrode structure, thereby improving overall touch sensitivity without requiring additional pixel areas.
Solution Approach 2:
The common electrode serves multiple functions: it acts as both the capacitive touch sensor electrode and the reference electrode for photo touch sensors. By making the common electrode universal, the patent eliminates the need for separate electrode structures for each sensor type, thus maintaining high aperture ratio while enabling dual sensor integration.
2Measurement precision
If photo touch sensor is integrated in the pixel area, then touch sensing capability is enhanced, but display quality deteriorates due to reduced aperture ratio
Solution Approach 1:
The patent merges the photo touch sensor structure with the existing display electrode structure. The photo touch sensor shares the common electrode and transparent electrode layers with the display function, combining touch sensing and light transmission functions into a single integrated structure. This merging eliminates the need for separate pixel areas for touch sensors, maintaining display quality while enabling touch sensing.
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 design enhances touch sensitivity and maintains high display quality by allowing for simultaneous touch sensing and display driving without occupying pixel areas, thus minimizing the decrease in aperture ratio.
Implementation Method 1
The photo touch sensor can recognize a touch based on the intensity of light
Implementation Method 2
The capacitive touch sensor can recognize a touch based on a variation of capacitance
Implementation Method 3
common electrodes configured to generate an electric field with pixel electrodes when applied with a common voltage during a display driving period
Data Source
AI summary
A display device having an open area and a non-open area surrounding the open area includes a pixel electrode and a common electrode disposed in the open area; a gate line disposed to extend in a first direction in the non-open area surrounding the open area and transmitting a gate signal to the pixel electrode; a data line disposed to extend in a second direction in the non-open area and transmitting a data signal to the pixel electrode; a plurality of sensing lines disposed in the non-open area and transmitting a common voltage or a touch scan signal to the common electrode; and a photo touch sensor disposed in the non-open area and electrically connected to one of the plurality of sensing lines.