Perimeter Touch Electrodes for Display Optical Uniformity
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Solution Overview
Problem
Conventional touch screens with electrodes overlaid on the display can compromise optical uniformity and increase manufacturing complexity, while existing perimeter touch electrode solutions may not efficiently integrate with display circuitry for accurate touch detection.
Innovation Solution
Implementing perimeter touch electrodes made of segmented frit metal around the display, coupled to touch sensing circuits via switching circuitry, which operates based on control signals shared with the display circuitry, allowing for self-capacitance and mutual-capacitance sensing without overlapping the display area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrodes are overlaid on the display to form a touch screen, then touch detection capability is improved, but optical uniformity deteriorates and manufacturing complexity increases
Solution Approach 1:
The touch electrode structure is extracted from the display area and relocated to the perimeter region. The perimeter touch electrodes are positioned outside the active display area, eliminating their visual impact on optical uniformity while preserving touch detection functionality through capacitive sensing of touches on the display surface.
Solution Approach 2:
The touch sensing function is transitioned from a two-dimensional overlay on the display surface to a perimeter-based configuration. By positioning electrodes along the edges and utilizing fringing electrical fields that extend toward the display center, the system achieves touch detection without compromising the visual area.
2Adaptability or versatility
If electrodes are overlaid on the display to form a touch screen, then touch detection capability is improved, but manufacturing complexity increases
Solution Approach 1:
The touch electrode fabrication process is merged with the existing display manufacturing process. The perimeter touch electrodes are formed using the same thin-film deposition and patterning techniques already employed for display circuitry, eliminating the need for separate overlay processes and reducing overall manufacturing complexity.
Solution Approach 2:
The display circuitry and control systems are designed to serve dual functions: driving the display and sensing touch inputs. The same control signals are used for both display operation and touch electrode actuation, reducing the need for separate dedicated touch sensing circuitry and simplifying the overall system architecture.
3Illumination intensity
If perimeter touch electrodes are used for touch detection, then optical uniformity is improved, but integration with display circuitry becomes more difficult
Solution Approach 1:
The perimeter touch electrodes are segmented into multiple discrete sections corresponding to different regions of the display. This segmentation allows independent control and sensing of different display areas, enabling precise touch location determination while simplifying the integration with display circuitry through modular signal handling.
Solution Approach 2:
The system implements feedback mechanisms where control signals sent to the perimeter touch electrodes generate capacitive responses that are measured and processed. This feedback loop enables accurate touch detection and position calculation, with the same control infrastructure being shared with display operations to reduce integration complexity.
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 enhances optical uniformity, reduces manufacturing complexity, and enables accurate touch detection on the display by utilizing perimeter touch electrodes that are integrated with the display circuitry for efficient sensing.
Implementation Method 1
capacitive-type touch sensing systems, fringing electrical fields used to detect touch can extend beyond the surface of the display
Data Source
AI summary
A touch screen may be formed from a display and perimeter touch electrodes. Touches detected at one or more of the perimeter touch electrodes can be imputed to touch on a region of the display of the touch screen adjacent to the perimeter touch electrodes. In some examples, the perimeter touch electrodes comprise segmented frit metal arranged around the perimeter of the display (e.g., frit metal used to encapsulate the display). In some examples, the perimeter touch electrodes can be coupled to one or more touch sensing circuits via switching circuitry. In some examples, the switching circuitry can be operated based on control signals shared with the display circuitry.