Matrix Sensor Electrodes with Protrusions for Touch Sensing
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Solution Overview
Problem
Existing capacitive touch sensing devices face limitations in detecting the presence and motion of input objects, especially when objects are far from the surface, as they rely on compact electric fields that are not effective for distant object detection.
Innovation Solution
The implementation of a capacitive touch sensing device with a planar matrix array of sensor electrodes and a grid electrode system, where each sensor electrode has a unique routing trace and a geometric plan with protrusions, allowing for both absolute and transcapacitive sensing modes to determine positional information of input objects within a sensing region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transcapacitive sensing methods are used to detect multiple input objects and motion, then detection capability for multiple objects is improved, but effectiveness for detecting objects spaced from the surface deteriorates
Solution Approach 1:
The sensing device is segmented into multiple independently addressable sensor electrodes arranged in a matrix array, allowing individual electrodes to be selectively activated for absolute capacitance sensing. This segmentation enables the system to maintain compact electric fields for multi-object detection while using specific electrodes for distant object detection through absolute capacitance measurements.
Solution Approach 2:
The sensing device dynamically switches between transcapacitive sensing mode for detecting multiple close objects and absolute capacitance sensing mode for detecting distant objects. This dynamic operation allows the system to adapt its sensing method based on the detection requirements, maintaining effectiveness across different object distances.
2Reliability
If absolute capacitance sensing is used to detect single input object at distance, then detection effectiveness for distant objects is improved, but capability to detect multiple input objects deteriorates
Solution Approach 1:
The matrix array of sensor electrodes is segmented into groups that can be independently operated. Specific electrodes can be selected and activated for absolute capacitance sensing when distant objects need to be detected, while other electrodes maintain transcapacitive sensing capability for multiple object detection, allowing both functions to coexist.
Solution Approach 2:
Each sensor electrode in the matrix array is designed to perform multiple functions: it can operate in transcapacitive mode for detecting multiple close objects and in absolute capacitance mode for detecting distant objects. This multi-functionality allows a single sensing device to handle both detection scenarios effectively.
3Measurement precision
If sensor electrodes are arranged in planar matrix array with protrusions, then capacitive coupling accuracy is improved, but device complexity increases
Solution Approach 1:
The sensor electrodes feature localized protrusions at specific positions rather than uniform geometry across the entire electrode surface. These protrusions are strategically positioned to optimize capacitive coupling with input objects, providing enhanced sensing accuracy only where needed while keeping the rest of the electrode structure relatively simple.
Solution Approach 2:
The electrode geometry extends from a simple planar surface into the third dimension with protrusions that overlap with adjacent electrodes. This dimensional addition creates interdigitated overlapping regions that enhance capacitive coupling accuracy without significantly increasing the planar footprint of the device.
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 the detection of input objects, including multiple objects and those in motion, by improving capacitive coupling accuracy and reducing parasitic capacitance, enabling effective sensing even when objects are not in direct contact with the surface.
Implementation Method 1
an array of sensor electrodes to measure a change in capacitance indicative of the presence of an input object
Implementation Method 2
an input object near the sensor electrodes alters the electric field near the sensor electrodes, thus changing the measured capacitive coupling
Data Source
AI summary
Embodiments described herein include an input device, a display device having a capacitive sensing device, a processing system and a method for detecting presence of an input object using a capacitive sensing device. In one embodiment, an input device includes a plurality of sensor electrodes arranged in a planar matrix array. Each sensor electrode is coupled to unique routing trace and has an identical geometric plan form that is symmetrical about a center of area of the sensor electrode. The geometric plan form of each sensor electrode includes core and a plurality of protrusions extending outward from the core. The protrusions are configured to overlap with protrusions extending outward from each adjacent sensor electrode of the matrix array.