Interleaving Capacitive Sense Array Layout for Stylus Accuracy
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Solution Overview
Problem
Capacitive touch-sensing systems face challenges in accurately detecting the presence and location of conductive objects, particularly narrow touch objects like passive styluses, due to limited spatial accuracy and sensitivity issues, especially when the sensor pitch is wider than the stylus tip, leading to dead zones and noise interference.
Innovation Solution
The implementation of capacitive-sense arrays with interleaving sense elements that extend dimensions beyond the sensor pitch, such as the double solid diamond (DSD) pattern, which enhances sensitivity and positional accuracy by creating wider signal profiles and reducing noise interference, allowing for precise detection of touch objects across a wider span.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sense elements with standard sensor pitch are used, then the device complexity remains low, but the measurement precision and sensitivity are insufficient for detecting narrow touch objects like passive styluses
Solution Approach 1:
The capacitive sense element is divided into multiple segments along its length, with each segment having a different sense element configuration. This segmentation allows each portion to detect touches at different positions along the electrode, improving overall measurement precision for narrow objects like styluses without requiring a completely complex new device architecture
Solution Approach 2:
Different portions of the capacitive sense element have different sense element configurations tailored to local detection needs. By varying the sense element pattern in different regions, the system achieves high measurement precision where needed while maintaining manageable device complexity through localized optimizations rather than global redesign
2Area of stationary object
If the sensor pitch is increased to cover wider areas, then the area of detection is improved, but the sensitivity to narrow touch objects decreases and dead zones are created
Solution Approach 1:
The patent extends the detection capability from a single sensor pitch dimension to multiple dimensions by incorporating sense elements that span across adjacent sensor pitches. This dimensional extension allows the system to maintain wide detection coverage while eliminating dead zones and improving sensitivity to narrow objects through multi-dimensional signal integration
Solution Approach 2:
Multiple sense elements from adjacent sensor pitches are merged to create an extended detection profile. By combining the signals from multiple sense elements that span across traditional pitch boundaries, the system achieves both wide area coverage and high sensitivity to narrow touch objects, eliminating the trade-off between coverage and precision
3Reliability
If traditional sense element patterns are used, then the ease of manufacture is maintained, but the reliability of touch detection for narrow objects is insufficient
Solution Approach 1:
The sense element pattern is segmented into repeating units that can be manufactured using standard fabrication processes. Each segment follows a manageable configuration that maintains ease of manufacture, while the overall pattern achieves high detection reliability through the coordinated operation of multiple segments
Solution Approach 2:
The sense element configuration uses periodic patterns that repeat at regular intervals along the capacitive electrode. This periodic structure maintains ease of manufacture by using repeating fabrication steps, while the specific periodic arrangement optimizes detection reliability for narrow touch objects through consistent signal characteristics across the electrode length
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 improves the sensitivity and accuracy of touch detection, enabling precise tracking of narrow objects like styluses and fingers, reducing positional errors, and eliminating dead zones, thus enhancing the performance of capacitive touchscreens in devices like tablets and smartphones.
Implementation Method 1
Capacitance sensing systems can sense electrical signals generated on electrodes that reflect changes in capacitance. Such changes in capacitance can indicate a touch event (i.e., the proximity of an object to particular electrodes).
Data Source
AI summary
Apparatuses and methods of sense arrays with interleaving sense elements are described. One capacitive-sense array includes a first electrode and a second electrode disposed adjacent to the first electrode in a first axis. The capacitive-sense array comprises a sensor pitch in the first axis. The first electrode includes a first sense element including a first shape and a first interleaving sense element that interleaves with a first portion and a second portion of the second electrode to extend a first dimension of the first electrode to be greater than the sensor pitch in the first axis. The second electrode includes a second sense element including the first shape and a second interleaving sense element that interleaves with a first portion and a second portion of the first electrode to extend a second dimension of the second electrode to be greater than the sensor pitch in the first axis.