Display Device Touch Sensor Routing for Reduced Dead Space
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Solution Overview
Problem
As display devices with increased resolution and touch sensors have more lines in the non-display region, this leads to an increase in the area of the dead space and reduced flexibility in bending or folding the device, as the number of sensing lines and pads increases, making it difficult to minimize the non-display region effectively.
Innovation Solution
The display device incorporates a second and fourth sensing line pattern that extend inside the encapsulation region, with a third sensing line pattern connecting them, allowing for a reduction in the number of lines in the bent region and decreasing the number of touch sensor pads and dead space area, thereby enhancing the flexibility of the device by reducing the width of the additional region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensing lines is increased to achieve higher resolution and touch sensor functionality, then the sensing capability is improved, but the area of the non-display region and dead space increases
Solution Approach 1:
The sensing lines are configured to extend in multiple directions (first direction along encapsulation layer, second direction underneath encapsulation layer, third direction perpendicular to both) to create a three-dimensional routing path. This multi-dimensional approach allows sensing lines to connect sensing electrodes to pads without increasing the two-dimensional footprint of the non-display region, effectively resolving the contradiction between sensing capability and dead space area.
Solution Approach 2:
The sensing lines are nested underneath the encapsulation layer in the second direction, with the lower side of the encapsulation layer serving as a protective cover. This nesting configuration allows sensing lines to be routed through the depth dimension rather than occupying additional horizontal space, reducing the dead space area while maintaining touch sensing functionality.
2Measurement precision
If the number of sensing lines and pads is increased to improve touch sensor resolution, then the sensing precision is improved, but the flexibility for bending or folding the device is reduced
Solution Approach 1:
The sensing lines route through the third dimension (underneath the encapsulation layer) to connect sensing electrodes to pads. This vertical routing approach concentrates the line integration in the depth direction rather than spreading lines across the bending surface, allowing the device to maintain flexibility for bending or folding while supporting high-resolution touch sensing with multiple sensing lines.
3Adaptability or versatility
If the sensing lines are routed extensively in the non-display region to connect all sensing electrodes, then the touch sensor coverage is improved, then the dead space area increases
Solution Approach 1:
Sensing lines are nested underneath the encapsulation layer, utilizing the space between the encapsulation layer and substrate. This configuration allows comprehensive touch sensor coverage with multiple sensing lines while minimizing the horizontal footprint, as the lines occupy the vertical space rather than expanding the dead space area in the planar dimension.
Solution Approach 2:
The sensing line routing transitions from two-dimensional horizontal routing to three-dimensional routing by extending underneath the encapsulation layer. This enables comprehensive sensor coverage to be achieved with reduced dead space area, as the routing occurs in the depth dimension rather than consuming additional horizontal space in the non-display region.
Data Source
AI summary
A display device includes a display panel that includes a substrate, a pixel disposed on the substrate, and an encapsulation layer that covers the pixel, and a touch sensor disposed on the display panel. The touch sensor includes sensing electrodes disposed on the encapsulation layer, and sensing lines respectively connected to the sensing electrodes. Each of the sensing lines includes a first sensing line pattern that extends onto the substrate, a second sensing line pattern connected to the first sensing line pattern outside of the encapsulation region, the second sensing line pattern including a first connection part and a second connection part, and a third sensing line pattern connected to the second connection part of the second sensing line pattern at a lower side of the encapsulation layer.