In-cell Touch LCD Virtual Electrodes for Transmissivity
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Solution Overview
Problem
Conventional in-cell mutual capacitance touch screens suffer from non-uniform transmissivity distribution and reduced display performance due to minimized drive and sense electrodes, leading to parasitic capacitances and noise interference, which impede accurate touch detection.
Innovation Solution
The introduction of virtual electrodes in the same layer as drive and sense electrodes, interconnected by bridges, fills the blank areas and reduces parasitic capacitances, ensuring uniform transmissivity and enhanced screen brightness while maintaining sufficient mutual capacitance for touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area of drive electrodes and sense electrodes is reduced to lower parasitic capacitances, then parasitic capacitances between electrodes are reduced, but transmissivity becomes non-uniform and display performance degrades
Solution Approach 1:
The electrode structure is segmented into drive electrodes, sense electrodes, and virtual electrodes. The virtual electrodes are placed in the blank areas between drive and sense electrodes, dividing the electrode system into functional segments that serve different purposes: drive/sense electrodes for touch detection and virtual electrodes for transmissivity compensation.
Solution Approach 2:
Different regions of the electrode structure are assigned different qualities and functions. Drive electrodes and sense electrodes are optimized for touch sensing with minimal area to reduce parasitic capacitance, while virtual electrodes are strategically placed in blank areas to compensate for transmissivity non-uniformity, giving each region its optimal local quality.
2Device complexity
If drive electrodes and sense electrodes are placed at very short distance from other electrodes to achieve in-cell integration, then device integration is improved, but parasitic capacitances and noise increase
Solution Approach 1:
Virtual electrodes act as intermediary elements between the drive/sense electrodes and other electrodes (common electrodes, pixel electrodes). These intermediary virtual electrodes help manage the electromagnetic field distribution and reduce the direct parasitic coupling between touch electrodes and other electrodes, thereby mitigating noise while maintaining in-cell integration.
Solution Approach 2:
The patent converts the harmful effect of close electrode proximity (which generates parasitic capacitance and noise) into a benefit by strategically placing virtual electrodes in the blank areas. These virtual electrodes, while close to other electrodes, are designed to compensate for transmissivity non-uniformity and actually reduce the net parasitic capacitance effect through their specific configuration and connection to the common electrode.
3Reliability
If blank areas are left in the touch sense electrode structure to minimize electrode area, then parasitic capacitance is reduced, but transmissivity distribution becomes non-uniform
Solution Approach 1:
The virtual electrodes perform multiple functions simultaneously: they fill the blank areas to improve transmissivity uniformity, they are connected to the common electrode to reduce parasitic capacitance effects, and they help stabilize the electrostatic field. This multi-functionality allows a single structural element to address multiple previously conflicting requirements.
Solution Approach 2:
The patent merges the functions of transmissivity compensation and parasitic capacitance reduction into a single integrated electrode system. The virtual electrodes are combined with the common electrode connection, so that the same structural feature (virtual electrodes in blank areas) achieves both transmissivity uniformity and parasitic capacitance reduction when properly connected.
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 achieves better transmissivity and higher screen brightness by uniformly distributing transmissivity and reducing parasitic capacitances, allowing for accurate and timely touch detection while eliminating electrostatic effects caused by object contact.
Implementation Method 1
a plurality of virtual electrodes are further disposed in the remaining area other than the drive electrodes and the sense electrodes... achieves better transmissivity and higher screen brightness by uniformly distributing transmissivity
Implementation Method 2
there are parasitic capacitances between the drive electrodes in the in-cell mutual capacitance touch screen and the other electrodes (e.g., the common electrodes), and between the sense electrodes in the in-cell mutual capacitance touch screen and the other electrodes (e.g., the common electrodes)... reduces parasitic capacitances
Implementation Method 3
a plurality of drive electrodes and a plurality of sense electrodes intersecting each other and having mutual capacitances formed between them... maintaining sufficient mutual capacitance for touch detection
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C
AI summary
The invention discloses a touch sensor, an in-cell touch liquid crystal display panel and a liquid crystal display, where the touch sensor includes a plurality of drive electrodes and a plurality of sense electrodes intersecting each other and having mutual capacitances formed between them ; and a plurality of virtual electrodes is disposed in a remaining area other than an area occupied by the drive electrodes and the sense electrodes, and wherein the virtual electrodes are located in a same layer as the drive electrodes and the sense electrodes. The liquid crystal display panel with an in-cell touch screen according to this technical solution has better transmissivity and high screen brightness; and together with reduced parasitic capacitances between the touch sensor and the other electrodes in the liquid crystal panel than the drive electrodes and the sense electrodes, sufficiently large mutual capacitances can be obtained for detection of a touch sense signal while electrostatic effects caused by a touch of the liquid crystal display panel by an object (e.g., a finger) are eliminated.