In-Cell Touch Display Pixel Pitch Reduction via Vertical Hole Alignment
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Solution Overview
Problem
In-cell type touch display devices face limitations in increasing resolution due to the presence of touch lines on the substrate, which restrict the reduction of pixel size and hence the number of pixels per area.
Innovation Solution
A touch display device design featuring a substrate with a thin film transistor, planarization layer, touch line, touch insulation layer, and touch electrode, where the planarization layer has a first hole corresponding to the drain electrode, and the touch insulation layer has a second hole with a first and second hole portion connected along a direction, allowing the touch electrode to contact the touch line through the second hole portion, thereby reducing pixel pitch and increasing resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If touch lines are provided on the substrate of the display panel in an in-cell type touch display device, then touch functionality is achieved, but the pixel size cannot be reduced further due to space constraints, limiting resolution increase
Solution Approach 1:
The patent utilizes the vertical dimension by stacking the touch electrode, touch line, and drain electrode in different layers along the thickness direction of the substrate. This three-dimensional arrangement allows touch components to occupy vertical space rather than horizontal pixel area, enabling pixel size reduction while maintaining touch functionality and achieving higher resolution
Solution Approach 2:
The touch electrode is positioned within the pixel region and nested above the drain electrode and touch line structure. The touch insulation layer with contact holes integrates the touch electrode connection with the underlying transistor structure, effectively nesting multiple functional elements within the pixel area to minimize space occupation
2Measurement precision
If the size of pixel is reduced to increase the number of pixels in the same area, then resolution is improved, but the area for touch lines and contact portions increases relative to pixel area, restricting further reduction
Solution Approach 1:
The touch line is integrated with the data line structure, and the touch electrode connection is merged with the transistor drain electrode connection. The touch insulation layer contact holes serve dual purposes of electrical connection for both the touch electrode and the underlying transistor elements, simplifying the overall layout and reducing the number of separate components needed
Solution Approach 2:
By moving touch components to different vertical layers, the patent eliminates the need for complex lateral routing of touch lines through pixel regions. The touch line can be routed in the horizontal direction at a different layer level, avoiding conflicts with pixel elements and simplifying the two-dimensional layout design
3Adaptability or versatility
If separate touch panel is attached to display panel, then touch functionality is achieved, but device thickness and complexity increase
Solution Approach 1:
The touch electrode, touch line, and associated insulation layers are integrated directly into the display panel substrate structure, merging the touch panel functions with the display panel fabrication process. This eliminates the need for a separate attached touch panel layer, reducing overall device thickness while maintaining full touch functionality
Solution Approach 2:
The substrate structure serves multiple functions simultaneously: it acts as both the display panel substrate and the touch panel substrate. The same layers that form the liquid crystal display also provide the touch sensing functionality, achieving multi-functionality within a single integrated structure
Data Source
AI summary
A touch display device includes a substrate; a thin film transistor over the substrate; a planarization layer over the thin film transistor; a touch line over the planarization layer; a touch insulation layer over the touch line; a touch electrode over the touch insulation layer; a pixel electrode over the touch electrode and connected to the thin film transistor, wherein the planarization layer has a first hole corresponding to a drain electrode of the thin film transistor, and the touch insulation layer has a second hole corresponding to the drain electrode, and wherein the second hole includes a first hole portion and a second hole portion connected to each other along a first direction, the first hole is disposed within the first hole portion, and the touch electrode is in contact with the touch line through the second hole portion.