On-Cell Touch Screen Noise Reduction via Insulating Layer
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Solution Overview
Problem
On-cell type touch screens in LCD devices are vulnerable to noise from the liquid crystal panel's driving, degrading touch sensing performance and limiting design flexibility, while existing noise-reducing technologies are costly and not widely applicable.
Innovation Solution
The implementation of a touch screen design with first and second touch electrodes separated by an insulation means, such as an upper polarizing film, and tempered glass, where the first touch electrodes are broader and formed on the upper substrate, and the second touch electrodes are on the lower surface of the tempered glass, with specific intervals and area ratios to minimize noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If touch electrodes are formed close to the liquid crystal panel for compact design, then device thickness is reduced, but noise from liquid crystal driving degrades touch sensing performance
Solution Approach 1:
The patent introduces an insulating layer as an intermediary substance between the touch electrodes and the liquid crystal panel. This insulating layer acts as a mediator that blocks noise from the liquid crystal driving circuitry while allowing the touch electrodes to remain in close proximity to the panel for compact design. The insulating layer thus enables both compactness and reliable touch sensing by mediating the interaction between the electrodes and the noisy liquid crystal panel.
Solution Approach 2:
The patent extracts the noise source from the touch sensing system by separating the touch electrodes from the liquid crystal panel structure. By forming touch electrodes on a separate substrate and positioning them adjacent to (but not integrated with) the liquid crystal panel, the design extracts the harmful electromagnetic noise while maintaining the functional proximity needed for compact device thickness.
2Reliability
If additional noise-resistant components are added to reduce noise, then touch sensing performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies multi-functionality by using existing structural layers (such as the upper polarizing film or color filter layer) as the insulating layer for noise reduction. Instead of adding a dedicated noise-blocking component, the design makes an existing layer serve the additional function of electrical insulation and noise blocking, thereby improving touch sensing performance without increasing device complexity.
Solution Approach 2:
The patent merges the noise reduction function with the existing touch electrode substrate structure. By integrating the insulating function into the substrate or existing layers rather than adding separate components, the design combines multiple functions (structural support, electrical insulation, noise blocking) into a single integrated structure, reducing overall complexity.
Data Source
AI summary
Discussed is an LCD device including a touch screen which reduces the influence of noise applied to the touch screen by driving of a liquid crystal panel and thus leads to enhancement of the touch sensing performance. The LCD device includes a liquid crystal panel, a plurality of first touch electrodes, an insulation unit, a tempered glass, and a plurality of second touch electrodes. The liquid crystal panel includes a lower substrate and an upper substrate. The first touch electrodes are formed on the upper substrate for detecting a touch point in a first direction. The insulation unit is formed on the first touch electrodes. The tempered glass is formed on the insulation unit. The second touch electrodes are formed at a lower surface of the tempered glass for detecting a touch point in a second direction.