Touch Sensor Circuit Merging Self and Mutual Capacitance
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Solution Overview
Problem
Current multi-touch sensing systems that combine mutual-capacitive and self-capacitive touch sensing are inefficient due to increased detection duration, affecting operation speed and accuracy, especially when environmental factors like humidity or screen contaminants are present.
Innovation Solution
A touch sensor circuit and method that simultaneously perform self-capacitive and mutual-capacitive sensing by charging a node between the two sensor circuits, allowing for concurrent detection and reducing overall sensing time through a control circuit that processes results from both sensing types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both mutual-capacitive and self-capacitive touch sensing are performed separately, then the accuracy of multi-touch sensing is improved and environmental affection is reduced, but the execution duration of touch sensing increases and operation efficiency becomes slower
Solution Approach 1:
The patent merges mutual-capacitive and self-capacitive sensing operations by charging a shared node between the two sensor circuits. The self-capacitive sensing is performed during the charging phase, while mutual-capacitive sensing is performed after the voltage reaches reference level, allowing both sensing types to complete within a single integrated cycle rather than separate executions.
Solution Approach 2:
The patent implements continuous sensing operations by eliminating idle time between sensing types. The self-capacitive sensing occurs continuously during the charging process, and the mutual-capacitive sensing immediately follows once the reference voltage is reached, creating an uninterrupted sensing sequence that maximizes resource utilization and minimizes total detection duration.
2Adaptability or versatility
If mutual-capacitive touch sensing is used, then multi-touch sensing capability is improved, but the sensing is easily affected by environment such as humidity, temperature, and screen contaminants
Solution Approach 1:
The patent employs a composite sensing approach that combines two different sensing methodologies (mutual-capacitive and self-capacitive) into a unified system. By fusing the results from both sensing types, the system leverages the multi-touch capability of mutual-capacitive sensing while using self-capacitive sensing to filter out environmental interference, creating a more robust detection system.
Solution Approach 2:
The patent implements feedback mechanisms where the control circuit processes results from both mutual-capacitive and self-capacitive sensing and uses this combined information to improve detection accuracy. The system continuously monitors environmental factors through self-capacitive sensing and adjusts the mutual-capacitive sensing results accordingly, compensating for environmental affections in real-time.
3Reliability
If self-capacitive touch sensing is used, then environmental affection is reduced, but multi-touch sensing capability is lost
Solution Approach 1:
The patent creates a universal sensing system where a single integrated circuit performs both self-capacitive and mutual-capacitive sensing functions. The shared node and control circuit are designed to support multiple sensing modes, allowing the system to automatically select or combine sensing types based on the operational requirements, thus achieving both environmental reliability and multi-touch capability within one system.
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 enhances multi-touch sensing accuracy, reduces environmental interference, and shortens detection duration, thereby improving the operational efficiency of touch sensing systems.
Implementation Method 1
Obtaining a voltage variation of a first capacitor by detecting the first capacitor by utilizing the self-capacitive sensor circuit
Implementation Method 2
Obtaining an output voltage of a second capacitor by detecting the second capacitor by utilizing the mutual-capacitive sensor circuit
Data Source
AI summary
A circuit for touch sensing includes a driving unit, a self-capacitive sensor circuit, a mutual-capacitive sensor circuit and a control circuit. The driving is configured to generate a driving signal. The self-capacitive sensor circuit is configured to generate a self-capacitance sensing result. The mutual-capacitive sensor circuit is configured to receive the driving signal in order to generate a mutual-capacitance sensing result when the voltage of a node between the self-capacitive sensor circuit and the mutual-capacitive sensor circuit reaches a reference voltage. The control circuit receives and computes the self-capacitance sensing result and the mutual-capacitance sensing result in order to generate a sensing result. By utilizing the circuit for touch sensing of present disclosure, the accuracy and the efficiency of touch sensing can be enhanced.