Capacitive Touch Panel Height Determination via Electrode Segmentation
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Solution Overview
Problem
Current capacitive touch panels struggle to accurately and reliably determine the height of objects above the surface, particularly in projected capacitance sensor matrices, due to complexities and inaccuracies in existing methods such as triangulation and the influence of object size, conductivity, and resistance to ground.
Innovation Solution
The capacitive touch panel employs an electrode array with drive and sense electrodes arranged in pairs, where one sense electrode is closer to the drive electrodes, allowing for differential capacitive coupling measurements to determine object height independently of size and conductivity, using a controller to calculate the object's distance based on variations in capacitance ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation method is used to determine object height, then height determination capability is added, but computational complexity and processing time increase significantly
Solution Approach 1:
The touch sensor surface is divided into multiple sensing zones with different electrode configurations. Each zone has electrodes positioned at different distances from the surface, creating segmented measurement regions that independently detect height information without requiring complex full-surface triangulation calculations.
Solution Approach 2:
The patent changes the physical parameter of electrode positioning by placing electrodes at different distances from the touch sensor surface. This creates zones with different sensitivity profiles to object height, allowing height determination through simple capacitance ratio comparisons rather than complex computational triangulation.
2Measurement precision
If multiple sensing zones with different electrode distances are implemented, then height determination accuracy improves, but device structure becomes more complex
Solution Approach 1:
The electrode array serves multiple functions: it detects touch position, determines object height, and distinguishes between different object types (finger vs. stylus). By making the sensing zones multi-functional, the patent avoids adding separate dedicated height-sensing structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent adds height detection capability by utilizing the vertical dimension (distance from surface) through strategically positioned electrodes. Instead of adding complex computational algorithms to a 2D touch surface, the solution physically extends sensing into the 3D space above the surface through electrodes at different heights/distances.
3Device complexity
If conventional capacitance measurement is used, then device simplicity is maintained, but ability to detect multiple simultaneous touch events is lost
Solution Approach 1:
The touch sensing surface is segmented into multiple independent sensing zones, each capable of detecting touch events. This segmentation allows multiple simultaneous touch events to be detected independently while maintaining relatively simple construction within each zone, resolving the contradiction between simplicity and multi-touch capability.
Solution Approach 2:
The patent introduces intermediate sensing zones with specific electrode configurations that act as mediators between the simple surface capacitance method and complex projected capacitance systems. These intermediate zones enable multi-touch detection with reduced complexity by providing localized sensing capabilities without requiring full projected capacitance matrix implementation.
4Measurement precision
If high sensitivity is increased to detect objects at distance, then height detection capability improves, but false detection of non-contact objects increases
Solution Approach 1:
Different regions of the touch sensor have different electrode configurations and sensitivities. Zones closer to the surface have different detection thresholds than zones farther away, allowing the system to distinguish between objects in genuine contact and objects merely in proximity. This local differentiation of sensing characteristics improves reliability without sacrificing overall sensitivity.
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 provides a simpler and more accurate method for height determination, applicable to projected capacitance sensor matrices, offering reliable object height calculation without the computational intensity of previous methods, and effectively distinguishing between objects in close proximity and those at a distance.
Implementation Method 1
The respective electrodes of the first or second electrode group are arranged to form multiple capacitances over different coupling distances
Implementation Method 2
a first electrode group comprising at least two drive electrodes and at least one sense electrode
Implementation Method 3
a controller operatively coupled to the array of electrode elements, the controller configured to determine a distance of an object relative to the surface of the touch sensor based on variations in the multiple capacitances
Data Source
AI summary
A capacitive touch sensor includes a sensor substrate and an array of electrode elements formed over the sensor substrate. Each electrode element of the array includes at least one of a first electrode group comprising at least two drive electrodes and at least one sense electrode, or a second electrode group comprising at least two sense electrodes and at least one drive electrode. The respective electrodes of the first or second electrode group are arranged to form multiple capacitances over different coupling distances. A controller is operatively coupled to the array of electrode elements, the controller configured to determine a distance of an object relative to the surface of the touch sensor based on variations in the multiple capacitances.