In-Cell Touch Panel Common Electrode Segmentation
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Solution Overview
Problem
Existing capacitive in cell touch panels require additional processes and materials, increasing production costs and complexity, and necessitate separate driving chips for touch and display functions, leading to potential interference and reduced image quality and touch accuracy.
Innovation Solution
A capacitive in cell touch panel design where the common electrode layer of the TFT array substrate is segmented into strip-shaped touch driving electrodes, allowing for time-sharing operation of touch and display functions, reducing the need for additional films and processes, and enabling integration of touch and display driving chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two layers of ITO electrodes are added on the TFT array substrate to form touch scanning lines and sensing lines, then touch functionality is achieved, but the structure of the TFT array substrate becomes complicated and production cost increases
Solution Approach 1:
The common electrode layer is designed to serve dual purposes: it functions as the common electrode for liquid crystal display and as the touch sensing electrode for capacitive touch detection. By making the common electrode layer extend across the entire display area and using it as both the common electrode and touch sensing electrode, the patent eliminates the need for separate touch sensing electrode layers, thereby reducing structural complexity while maintaining both display and touch functionalities
Solution Approach 2:
The patent combines the common electrode layer and touch sensing electrode into a single integrated structure. The common electrode layer is configured to extend across the entire display area and serves both as the common electrode for LCD operation and as the sensing electrode for touch detection, merging two previously separate functional layers into one
2Adaptability or versatility
If two driving chips are used simultaneously for touch driving and display driving, then both functions are achieved, but production cost increases
Solution Approach 1:
A single driving chip is designed to perform multiple functions by time-division multiplexing. The chip alternates between displaying image data and scanning touch signals during different time periods within each frame cycle, eliminating the need for separate touch and display driving chips while reducing production cost and system complexity
Solution Approach 2:
The driving chip operates in periodic cycles, alternating between image display mode and touch scanning mode. During each frame period, the chip first displays image data during the display period, then switches to scanning touch signals during the touch period, creating a periodic alternation between the two functions that allows one chip to handle both tasks
3Adaptability or versatility
If additional processes are added when manufacturing the TFT array substrate, then touch functionality is integrated, but production cost increases
Solution Approach 1:
The touch sensing electrode is merged with the common electrode layer, allowing both touch and display functions to be manufactured using the same existing TFT array substrate processes. This integration eliminates the need for additional touch-specific manufacturing processes while achieving full touch functionality
Solution Approach 2:
The common electrode layer is designed to fulfill dual roles, serving both as the common electrode for liquid crystal display operation and as the touch sensing electrode for capacitive touch detection. This multi-functional design allows the existing common electrode manufacturing process to produce a layer that performs both functions, eliminating the need for separate touch electrode manufacturing processes
4Reliability
If separate driving chips are used for touch and display, then functional independence is achieved, but image quality and touch accuracy are reduced due to interference
Solution Approach 1:
The single driving chip uses periodic time-division multiplexing to alternately perform display and touch scanning functions. During the display period, image data is written to pixel electrodes; during the touch period, scanning signals are applied to the common electrode for touch detection. This periodic separation in time eliminates signal interference between the two functions while maintaining functional integration
Solution Approach 2:
The frame period is segmented into distinct display period and touch period. By dividing the time domain into separate intervals for different functions, the patent eliminates signal interference that would occur if both functions operated simultaneously, thereby improving both image quality and touch accuracy while using a single integrated chip
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 simplifies the TFT array substrate structure, reduces production costs, increases efficiency, and improves image quality and touch accuracy by minimizing functional interference through time-sharing operation.
Implementation Method 1
a capacitive in cell touch panel, the touch sensing electrode and the touch driving electrode are used to form a capacitor
Implementation Method 2
when a human body contacts the touch panel, electric field of the human body will act on the inductive capacitor so that capacitance of the inductive capacitor will change
Implementation Method 3
capacitance of the inductive capacitor will change, which in turn change the voltage signal coupled from the touch sensing line
Data Source
Figure 1~2
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Figure 4
AI summary
The present invention discloses a capacitive in cell touch panel and display device, wherein touch sensing electrodes are provided on a color filter substrate, the whole common electrode layer of the TFT array substrate is segmented into a plurality of strip-shaped structures functioning as touch driving electrodes, and the touch driving electrodes are driven in a time-sharing manner to achieve the touch function and the display function in a time-sharing manner. Since in the touch panel according to the present invention, structure of the common electrode layer of the TFT array substrate is altered to form the touch driving electrodes, it is not necessary to add a new film on the existing TFT array substrate and only an additional process needs to be added to segment the whole common electrode layer into a plurality of strip-shaped structures, reducing the production cost and increasing the production efficiency.