Touchscreen Sensor EMI Shielding via Filtered Conductor Grid
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Solution Overview
Problem
Touchscreen displays, particularly in aircraft systems, face electromagnetic interference (EMI) issues due to the lack of EMI shielding on the display surface, which can disrupt internal components and reduce touch sensor accuracy, and transparent conductive layers like ITO are expensive and affect optical transmission.
Innovation Solution
A network of filters is coupled to the grid of conductors in the touchscreen sensor, allowing a specific touchscreen sensor frequency band to pass through while filtering out EMI frequencies and grounding them to the display chassis, eliminating the need for a transparent conductive layer and reducing material and labor costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transparent conductive layer (ITO) is applied across the display surface to provide EMI shielding, then EMI protection is improved, but cost increases and optical transmission decreases
Solution Approach 1:
The patent extracts the EMI shielding function from the transparent conductive layer (ITO) and implements it through a different mechanism: using the touchscreen sensor conductor grid combined with filters and grounding. This removes the need for the expensive ITO layer while maintaining EMI protection through the filter-grounding system that directs EMI to ground.
Solution Approach 2:
The touchscreen sensor conductor grid is given multiple functions: it serves as both the touch detection sensor and as part of the EMI shielding system when combined with filters and grounding. This multi-functional approach eliminates the need for separate EMI shielding layers.
2Object-affected harmful factors
If a transparent conductive layer (ITO) is applied across the display surface to provide EMI shielding, then EMI protection is improved, but optical transmission decreases
Solution Approach 1:
The patent removes the transparent conductive layer (ITO) from the display stack while extracting its EMI shielding function and implementing it through the touchscreen sensor grid with filters and grounding. This maintains optical transmission by eliminating the ITO layer that would otherwise block light.
Solution Approach 2:
The patent changes the approach to EMI shielding from using a continuous transparent conductive layer to using a grid structure with filters. This parameter change in the shielding mechanism allows optical transmission to pass through the grid openings while EMI is blocked by the conductive elements and filtered.
3Object-affected harmful factors
If a transparent conductive layer (ITO) is applied across the display surface to provide EMI shielding, then EMI protection is improved, but touch sensor accuracy decreases
Solution Approach 1:
The patent removes the transparent conductive layer that was interfering with touch sensor accuracy and extracts the EMI shielding function to be provided by the sensor's own conductor grid combined with filters and grounding. This eliminates the source of accuracy degradation while maintaining EMI protection.
Solution Approach 2:
The touchscreen sensor system serves itself by using its own conductor grid, combined with filters and grounding, to provide EMI shielding. This self-service approach eliminates the need for external ITO layers that would interfere with sensor performance.
4Object-affected harmful factors
If filters are coupled to the conductor grid and grounded to shield EMI, then EMI protection is improved, but device complexity increases
Solution Approach 1:
The patent merges the EMI filtering function with the existing touchscreen sensor conductor grid structure. The filters are integrated into the sensor architecture and grounded to the chassis, combining multiple functions (touch sensing and EMI shielding) into a unified system rather than adding separate shielding layers.
Solution Approach 2:
The conductor grid serves multiple functions: touch detection and EMI shielding when combined with filters and grounding. This multi-functionality reduces the need for additional separate components and simplifies the overall system architecture.
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 effectively shields the display surface from EMI, maintains touch sensor accuracy, and improves optical transmission without the need for expensive transparent conductive layers, thereby reducing costs and enhancing performance.
Implementation Method 1
Each of the filters may be configured to allow a touchscreen sensor frequency band of interest to pass through said filter such that the touchscreen sensor is configured to detect touches. Each of the filters may be configured to filter out electromagnetic interference (EMI) on frequencies other than the touchscreen sensor frequency band of interest and to ground the EMI to the display chassis.
Implementation Method 2
The touchscreen sensor and the filters may form an EMI shield across the display surface of the touchscreen display.
Data Source
AI summary
A touchscreen display may include display chassis, a touchscreen sensor, and filters. The touchscreen sensor may include row conductors and column conductors spanning a display surface. Each of the filters may be coupled to one of the row conductors or the column conductors such that the row conductors and the column conductors are coupled to the filters. Each of the filters may be grounded to the display chassis. Each of the plurality of filters may be configured to allow a touchscreen sensor frequency band of interest to pass through said filter such that the touchscreen sensor is configured to detect touches. Each of the filters may be configured to filter out electromagnetic interference (EMI) on frequencies other than the touchscreen sensor frequency band of interest and to ground the EMI to the display chassis. The touchscreen sensor and the filters may form an EMI shield across the display surface.