Shield Electrode Noise Rejection in Resistive Touch Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current touch sensors face challenges in accurately detecting and characterizing force inputs on surfaces due to noise interference from external electronic components, which affects the reliability and precision of resistance data collection.
Innovation Solution
A system comprising a resistive touch sensor, a force-sensing layer, and a shield electrode, where the controller drives the shield electrode to a virtual reference potential during resistance scan cycles to reject noise, and processes resistance values into force touch images, while also using capacitance sensing to detect proximity and adjust sensitivity and scan resolution based on capacitance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistive touch sensor is used to detect force inputs, then force detection capability is provided, but noise interference from external electronic components reduces measurement accuracy
Solution Approach 1:
A shield electrode is introduced as an intermediary component between the resistive touch sensor and external electronic components. The shield electrode is driven to a virtual reference potential during resistance scan cycles to actively reject noise interference from external electronic components, thereby protecting the force detection process without requiring physical isolation or shielding structures.
Solution Approach 2:
The system dynamically changes the electrical potential parameter of the shield electrode to a virtual reference potential during resistance scan cycles. This parameter change enables the shield electrode to actively track and reject noise signals from external electronic components, improving force detection accuracy without adding physical complexity.
2Measurement precision
If resistive sensing is used for force detection, then force magnitude information is obtained, but capacitance variations from nearby objects cause false readings
Solution Approach 1:
The system merges resistive sensing and capacitive sensing techniques into a unified detection system. The controller simultaneously processes resistance values from the resistive touch sensor and capacitance values from the shield electrode, combining the advantages of both methods to distinguish between force-induced resistance changes and proximity-induced capacitance changes.
Solution Approach 2:
The system uses capacitance sensing as a feedback mechanism to detect object proximity. When capacitance variations indicate the presence of nearby objects, the controller adjusts its interpretation of resistance values accordingly, compensating for potential false readings and improving force measurement reliability.
3Measurement precision
If uniform scan resolution is used across the entire sensor surface, then comprehensive coverage is achieved, but processing time increases
Solution Approach 1:
The system dynamically adjusts scan resolution based on detected activity or regions of interest. Instead of uniformly scanning the entire sensor surface at high resolution, the controller adapts the scan resolution to focus computational resources on areas where force inputs are detected or where capacitance variations indicate object proximity, thereby reducing overall processing time while maintaining detection precision where needed.
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
The system effectively reduces noise interference, enhances the accuracy of force input detection, and improves the reliability of touch data collection by integrating resistive and capacitive sensing techniques, allowing for precise characterization of force inputs and object proximity.
Implementation Method 1
comprising a force-sensitive material exhibiting variations in local bulk resistance responsive to local variations in applied force
Implementation Method 2
a first shield electrode arranged over the force-sensitive material and electrically coupled to the substrate, wherein the controller is configured to drive the first shield electrode to a virtual reference potential during a resistance scan cycle
Implementation Method 3
reading a capacitance value of the first shield electrode, and to detect proximity of an object to the surface based on the capacitance value
Data Source
AI summary
One variation of a method for detecting and characterizing force inputs on a surface includes: during a resistance scan cycle of a sampling period, driving a shield electrode arranged over a resistive touch sensor to a reference potential and reading resistance values across sense electrode and drive electrode pairs in the resistive touch sensor; during a processing cycle of the sampling period, transforming the resistance values into a position and a magnitude of a force applied to a tactile surface over the shield electrode, releasing the shield electrode from the reference potential, reading a capacitance value of the shield electrode, and detecting proximity of an object to the tactile surface based on the capacitance value; and generating a touch image representing the position and the magnitude of the force on the tactile surface based on the proximity of the object to the tactile surface.