Touch Sensor Layout for Enlarged Active Area Displays
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Solution Overview
Problem
Designing compact displays with small form factors to maximize both display area and touch sensing region is challenging, particularly in wearable devices like smartwatches, as integrating touch sensing technology often requires trade-offs between these two areas.
Innovation Solution
Integrate a touch sensor between the cover layer and the pixel array, with touch trace routings disposed between the cover layer and pixels, allowing for an enlarged active area by positioning diodes and transistors to extend beyond the driving circuitry, thus maintaining a larger display area without reducing the space allocated to driving circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If touch sensing technology is integrated above a compact display in wearable devices, then the touch sensing region can be maximized, but the display area is reduced
Solution Approach 1:
The patent positions the light-emitting elements (diodes) in a third dimension above the driving circuitry plane, allowing them to extend beyond the traditional display boundaries. This vertical stacking approach enables the display area to exceed the area occupied by the driving circuitry without increasing the horizontal footprint, thereby maximizing both display and touch sensing regions within compact wearable form factors.
Solution Approach 2:
The patent implements a nested structure where the light-emitting elements are positioned above and extend beyond the driving circuitry, which is itself integrated within the compact display assembly. This nesting allows multiple functional layers to occupy overlapping spatial regions, enabling the display area to be enlarged without proportionally increasing the overall device footprint.
2Area of moving object
If the display area is enlarged by extending pixels beyond driving circuitry, then the active display area increases, but the layout complexity increases
Solution Approach 1:
The patent segments the display into distinct functional regions: a driving circuitry region containing the transistors and circuit elements, and an extended emitting region containing the light-emitting elements that protrude beyond the driving circuitry. This segmentation allows independent optimization of each region, simplifying the overall layout by clearly defining functional zones rather than requiring complex integrated patterns.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the display. The driving circuitry region maintains standard planar integration, while the extended emitting region features light-emitting elements positioned at elevated positions that extend beyond the driving circuitry boundaries. This local differentiation allows the display to achieve enlarged active area without imposing complex three-dimensional structures throughout the entire device.
Data Source
AI summary
This document describes systems and techniques directed to touch sensor integration with enlarged active area displays. In aspects, a display includes a cover layer, an array of pixels, and a plurality of transistors that control an electrical activation of one or more pixels of the array of pixels. The plurality of transistors define a smaller area than the array of pixels such that at least one pixel of the array of pixels extends beyond the area defined by the plurality of transistors and above driving circuitry (“extended emitting area”). Variable pixel and/or transistor densities can support the extended emitting area. A touch sensor is integrated between the cover layer and the array of pixels and is operatively coupled to one or more touch trace routings that are, at least partially, disposed between the cover layer and one or more pixels within the extended emitting area.