Shielding Electrodes Reduce Parasitic Capacitance in Touch Sensor Displays
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Solution Overview
Problem
Existing touch sensor technologies for display devices face challenges in reducing device thickness and increasing sensitivity, with add-on type sensors increasing thickness and on-cell type sensors being limited by parasitic capacitance from touch driving and sensing electrodes.
Innovation Solution
A touch sensor integrated type display device is designed with touch driving and sensing electrodes formed as components of the display device, utilizing a common electrode for liquid crystal driving and incorporating shielding electrodes to reduce parasitic capacitance and thickness, allowing for integrated formation without separate electrode layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If add-on type touch sensor is mounted on display device, then touch sensing function is added, but thickness of display device increases
Solution Approach 1:
The patent merges the touch sensor electrodes with the display device electrodes by forming touch driving electrodes and touch sensing electrodes on the same substrate as the display electrodes. This integration eliminates the need for separate add-on touch sensor layers, thereby adding touch sensing functionality while avoiding increase in device thickness.
Solution Approach 2:
The patent makes the display electrodes serve dual functions: as display electrodes for image rendering and as touch sensor electrodes for touch detection. The first electrodes serve both as common electrodes for liquid crystal driving and as touch driving electrodes, while the second electrodes serve both as pixel electrodes and as touch sensing electrodes, achieving multi-functionality without additional layers.
2Length of stationary object
If on-cell type touch sensor is formed on glass substrate, then thickness is reduced compared to add-on type, but parasitic capacitance increases due to touch driving electrode layer and touch sensing electrode layer
Solution Approach 1:
The patent extracts and eliminates the parasitic capacitance problem by strategically positioning shielding electrodes between the touch driving electrodes and touch sensing electrodes. The shielding electrodes are connected to a reference potential, which shields the sensing electrodes from electric field interference generated by the driving electrodes, thereby reducing parasitic capacitance effects.
Solution Approach 2:
The shielding electrodes act as an intermediary element between the touch driving electrodes and touch sensing electrodes. These shielding electrodes, being electrically connected to a reference potential, mediate the electric field interaction by blocking or reducing the direct coupling between driving and sensing electrodes, thus reducing parasitic capacitance.
3Measurement precision
If touch driving electrodes and touch sensing electrodes are added as separate layers, then touch sensitivity is improved, but device thickness increases
Solution Approach 1:
The patent combines the formation of touch electrodes with the formation of display electrodes in the same manufacturing process. The touch driving electrodes and touch sensing electrodes are formed on the same substrate as the display common electrode and pixel electrodes respectively, using the same transparent conductive material and processing steps, thereby achieving touch sensitivity without additional thickness.
Solution Approach 2:
The patent assigns multiple functions to existing electrode layers: the first electrodes serve as both common electrodes for display and touch driving electrodes, while the second electrodes serve as both pixel electrodes for display and touch sensing electrodes. This multi-functionality approach enables touch sensitivity enhancement without requiring separate dedicated touch electrode layers.
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 solution reduces the thickness of the display device and increases touch sensitivity by minimizing the change in capacitance generated by touch events, while also reducing the influence of electric fields on liquid crystals, thereby enhancing display performance.
Implementation Method 1
a shielding electrode formed between each first electrode and each second electrode
Implementation Method 2
capacitance generated by touch driving electrodes
Data Source
AI summary
A touch sensor integrated type display device includes a plurality of gate lines and a plurality of data lines which are formed to cross over each other; a plurality of pixel electrodes respectively formed in areas defined by crossings of the plurality of gate lines and the plurality of data lines; a plurality of first electrodes, each of which is formed between the pixel electrodes and in parallel with the gate line, the pixel electrodes being adjacent to each other with the gate line interposed therebetween; a plurality of second electrodes formed in parallel with the data lines, at least a portion of each of the plurality of second electrodes overlapping the pixel electrode; and a shielding electrode formed between each first electrode and each second electrode.