Transparent Capacitive Touch Electrode Layout for Ghost-Point Reduction
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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 diagonal touchpads and vehicle applications, where single and dual touch recognition are common, and 'ghost points' can occur, restricting the design variety and increasing installation space.
Innovation Solution
An arrangement with an electrically insulating substrate featuring alternating, uniformly shaped conductive surfaces of two types, where surfaces of one type are connected in rows and the other in columns, allowing for a regular pattern with non-compliant areas that maintain minimum distance, enabling improved touch location resolution and accommodating symbols or orientation aids without compromising sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strictly regular pattern of electrode surfaces is used, then spatial resolution and touch detection accuracy are improved, but design variety is restricted and installation space is increased
Solution Approach 1:
The patent applies local quality by allowing geometric deviations from the regular pattern in specific local areas where symbols or orientation aids are needed, while maintaining the regular pattern in other areas. This enables design variety and space optimization without compromising overall spatial resolution, as the deviations are localized and do not affect the global electrode density and arrangement.
2Device complexity
If geometric deviations from regular pattern are introduced to accommodate symbols or orientation aids, then design variety and space utilization are improved, but spatial resolution and touch detection accuracy deteriorate
Solution Approach 1:
The patent introduces local geometric deviations in specific areas to accommodate symbols or orientation aids while maintaining the regular pattern elsewhere. This localized approach allows design variety without significantly impacting overall spatial resolution, as the deviations are confined to specific regions and do not affect the global electrode density.
Solution Approach 2:
The patent applies partial action by introducing geometric deviations only in the minimum necessary areas to accommodate symbols or orientation aids, rather than altering the entire electrode pattern. This partial modification maintains spatial resolution in the majority of the touchpad area while providing design flexibility where needed.
3Measurement precision
If electrode density is increased to improve spatial resolution, then touch detection accuracy is improved, but installation space and device dimensions are increased
Solution Approach 1:
The patent optimizes electrode density by adjusting parameters such as electrode size, spacing, and shape to achieve the required spatial resolution within the available installation space. By carefully tuning these parameters, the system maintains high touch detection accuracy without unnecessarily increasing the overall device dimensions.
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 configuration enhances multi-touch detection capabilities, maintains spatial resolution near non-compliant areas, and allows for a user-friendly, space-saving control surface design suitable for vehicles by compensating for geometric deviations and optimizing electrode density, thus reducing 'ghost points' and improving touch sensitivity.
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
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. If you touch the touchpad near an intersection, part of the mutual capacitance between row and column is coupled to the finger and the electrical capacitance of the intersection measured by the evaluation unit is reduced.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to 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 forming an essentially regular pattern due to their generic, regular surface structure and placement, wherein a region (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 area (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 an area 4a is arranged above a translucent substrate 5 or an area in the substrate 5 which is translucent.