Capacitive Touch Electrode Layout Around Apertures for Multi-Touch Accuracy
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Solution Overview
Problem
Projected-capacitive touch detection systems face limitations in multi-touch recognition and spatial resolution due to geometric deviations from a strictly regular electrode pattern, particularly in large touchpads and vehicle applications, where single and dual touch recognition are common, and 'ghost points' can occur, limiting the capability to accurately detect multiple touches.
Innovation Solution
An arrangement with an electrically insulating substrate featuring conductive surfaces of alternating types, where non-compliant surfaces are strategically positioned to maintain minimum distances and deformations, allowing for enhanced touch detection resolution and multi-touch capability while accommodating design features like symbols and orientation aids, using mutual capacitance principles and software compensation to maintain sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strictly regular electrode pattern is used, then touch detection resolution is maximized, but design flexibility and installation space are reduced
Solution Approach 1:
The patent applies local quality by allowing geometric deviations from the regular electrode pattern only in specific local areas where openings are present, while maintaining the regular pattern in other regions. This enables the electrode structure to accommodate design features like symbols and orientation aids without compromising overall touch detection resolution, as the regular pattern is preserved in areas where high resolution is critical.
2Adaptability or versatility
If electrode surfaces are deformed to accommodate openings, then design variety is improved, but touch detection resolution is disrupted
Solution Approach 1:
The patent implements local quality by deforming only those electrode surfaces that directly adjoin openings, while keeping all other electrode surfaces in the regular alternating pattern. This localized deformation approach allows design variety in areas with openings while preserving touch detection resolution in areas with the regular pattern.
Solution Approach 2:
The patent applies partial action by selectively deforming only the necessary electrode surfaces that are in direct contact with or adjacent to openings, rather than deforming the entire electrode structure. This minimizes the impact on overall touch detection resolution while still accommodating design features.
3Measurement precision
If a strictly regular pattern is maintained, then resolution capacity is optimized, but installation space and operational design are compromised
Solution Approach 1:
The patent uses local quality to maintain the regular alternating pattern in most areas to preserve resolution capacity, while allowing local deviations only where openings are present. This enables space-saving designs with symbols and orientation aids without significantly compromising overall touch detection resolution.
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 approach enables a user-friendly, space-saving, and clear control surface for vehicles by retaining touch detection resolution and sensitivity even with geometric deviations, allowing for accurate multi-touch detection and reduced 'ghost points', enhancing the operational design and user experience.
Implementation Method 1
Projected capacitive technology detects touch by measuring the electrical capacitance at each addressable electrode. When a finger or conductive stylus approaches an electrode, its electromagnetic field is disturbed and its electrical capacitance is altered.
Implementation Method 2
When a finger or conductive stylus approaches an electrode, its electromagnetic field is disturbed and its electrical capacitance is altered.
Implementation Method 3
Mutual capacitance is the intentional or unintentional electrical capacitance between two charged objects. With projected-capacitive touchpads (pcap touch), a mutual capacitance is deliberately built up between the elements of rows and columns in the vicinity of the individual intersections.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An arrangement for spatially resolved projected capacitive touch detection comprising an electrically insulating substrate (5) with several electrically conductive surfaces of the first type (1) and the second type (2) arranged side by side on the substrate, wherein the surfaces within a type regularly have a uniform surface structure, and wherein the surfaces of the first type (1) are electrically connected to each other to form several transmitting electrodes and the surfaces of the second type (2) are electrically connected to form several receiving electrodes, and are arranged essentially forming a regular pattern due to their generic, rule-compliant surface structure and placement, wherein a breakthrough (4) is formed in the substrate (5), wherein the receiving electrodes are connected column-wise and the transmitting electrodes are connected row-wise,that the surfaces of the first type (1) and the surfaces of the second type (2) are arranged alternately, that the surface of one type (6) is surrounded by several surfaces of the other type (7) maintaining a minimum distance (3), and that at least one first surface (1b, 2a) of the first type (1) or second type (2) adjacent to the opening (4) is provided, which is not designed in accordance with the rules with regard to its generic surface design and/or placement in such a way that the specified minimum distance (3) to at least two nearest adjacent surfaces (1a, 1a') of the other type is achieved, characterized in that the surfaces 1a, 2a, which are located around an opening 4, are designed in such a way that they are not specified by a surface deformation or a perimeter optimization, but have a shape outside the opening 4,which would correspond to the shape, in particular the contour, without any opening.