Touch Sensor Charge Imbalance Compensation
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Solution Overview
Problem
Capacitive touch sensors with non-rectangular sensor arrays face challenges in differential signal processing due to uneven numbers of sensor nodes, leading to charge imbalances and reduced signal path gain.
Innovation Solution
A touch controller apparatus with a capacitance-to-voltage converter, signal balancing circuit, and analog-to-digital converter that adds a balancing signal to the input signal to compensate for the number of sensor nodes, generating a balanced input signal to improve differential signal processing and reduce charge imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If differential signal processing is used in capacitive touch sensors with non-rectangular sensor arrays, then signal processing capability is improved, but charge imbalances occur due to uneven numbers of sensor nodes
Solution Approach 1:
The patent applies preliminary action by adding a balancing signal to the input signal before processing. The balancing signal is generated based on the number of sensor nodes and is added in advance to compensate for charge imbalances, ensuring that the differential signal processing operates on balanced signals from the outset.
Solution Approach 2:
The patent changes the parameter of the input signal by adding a balancing signal with specific magnitude and phase characteristics. The balancing signal's parameters are adjusted based on the number of sensor nodes present, transforming the unbalanced input signal into a balanced signal suitable for differential processing.
2Adaptability or versatility
If sensor arrays with varying numbers of sensor nodes are used to achieve non-rectangular shapes, then adaptability is improved, but signal path gain is reduced due to charge imbalances
Solution Approach 1:
The patent maintains adaptability for non-rectangular sensor arrays by dynamically adjusting the balancing signal parameters based on the actual number of sensor nodes. This parameter adjustment compensates for charge imbalances, preserving signal path gain while allowing flexible sensor array configurations.
Solution Approach 2:
The system uses feedback by determining the actual number of sensor nodes and using this information to generate an appropriate balancing signal. This feedback loop ensures that the balancing signal is optimized for the specific sensor array configuration, maintaining signal path gain across different shapes.
3Measurement precision
If charge imbalance compensation is applied through signal balancing circuitry, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent improves measurement precision by changing the parameters of the input signal through adding a balancing signal. The balancing signal's magnitude and phase are adjusted based on sensor node count, enabling accurate touch sensing measurements while using relatively simple circuit implementation.
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 solution effectively adjusts the input signal to mimic a balanced layout, enhancing differential signal processing and reducing charge imbalances in non-rectangular sensor arrays, thereby improving the accuracy and reliability of touch sensing measurements.
Implementation Method 1
a capacitance-to-voltage converter coupled with the connector to generate a voltage signal indicative of an associated mutual capacitance of the receiver electrode
Data Source
AI summary
A process includes receiving an associated input signal via a receiver electrode of a sensor array, the associated input signal indicative of an associated mutual capacitance of the receiver electrode; adding a balancing signal to the associated input signal to generate a balanced input signal at least partially responsive to a number of sensor nodes at the receiver electrode; generating a voltage signal indicative of the associated mutual capacitance of the receiver electrode at least partially responsive to a balanced input signal; and generating a digital value representative of the voltage signal.