Mutual capacitive touch sensing anomaly detection

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Solution Overview

Problem

Conventional threshold-based systems for mutual capacitive touch sensing are inadequate in detecting anomalies, as they may fail to distinguish between intentional and unintentional touch events and cannot accurately identify damage to sensor traces, requiring additional hardware and complex configurations.

Innovation Solution

A method involving a processor that measures capacitance changes by dynamically configuring ports to create and swap electric fields, allowing for the comparison of mutual capacitance changes under different configurations to determine anomaly likelihood without additional hardware, using a threshold-based system to differentiate between normal and anomalous operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional threshold-based systems are used for mutual capacitive touch sensing, then the system structure remains simple, but the system cannot accurately distinguish between intentional and unintentional touch events or detect trace damage

Engineering Contradiction:
Improveanomaly detection accuracyVSAvoidsystem configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system dynamically swaps the configuration of transmit and receive ports between different measurement cycles. In the first cycle, port 1 is configured as transmit and port 2 as receive; in the second cycle, their roles are reversed. This dynamic reconfiguration enables the system to detect anomalies by comparing capacitance measurements from different port assignments, improving reliability without adding hardware complexity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of the touch sensor by swapping port configurations between measurement cycles. This parameter change allows the same physical sensor to be measured from different electrical perspectives, enabling detection of trace damage and false touch events through comparison of the swapped configurations

Inventive Principle:
Principle #35Parameter changes

2Reliability

If additional hardware is added to detect sensor trace damage and distinguish touch events, then anomaly detection capability improves, but device complexity and cost increase

Engineering Contradiction:
Improvesensor anomaly detectionVSAvoidhardware requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The touch sensor system performs self-diagnosis by swapping its own port configurations and comparing measurements. The existing transmit and receive ports are reused in reversed roles, allowing the system to detect trace damage and anomalies using its own resources without requiring additional test hardware or external diagnostic equipment

Inventive Principle:
Principle #25Self-service

3Measurement precision

If port configurations are swapped to detect anomalies, then measurement precision for anomaly detection improves, but measurement time increases due to multiple measurements

Engineering Contradiction:
Improveanomaly detection precisionVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs periodic measurements by alternating between two port configurations in successive measurement cycles. The first cycle measures with port 1 as transmit and port 2 as receive, while the second cycle swaps them. This periodic action enables anomaly detection through comparison while maintaining efficient measurement timing through regular alternating patterns

Inventive Principle:
Principle #19Periodic action

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 effectively identifies anomalies in mutual capacitive touch sensors by analyzing differences in capacitance measurements from swapped port configurations, reducing false positives and detecting trace damage without requiring extra hardware, thus enhancing error detection in capacitive touch systems.

Implementation Method 1

a capacitive element can be formed by two conductive elements that can generate an electric field

Methodology Applied
Scientific EffectElectric field: Electric Field

Implementation Method 2

The mutual capacitance between the two conductive elements forming the capacitive element can change

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP4068631A1Mutual capacitive touch sensing anomaly detection
Publication Date: 2022.10.05 RENESAS ELECTRONICS CORP
  • EP4068631A1 patent drawingFigure 1
  • EP4068631A1 patent drawingFigure 2
  • EP4068631A1 patent drawingFigure 3A~3B

AI summary

Systems and methods for determining a likelihood of an occurrence of an anomaly in a sensor are described. A processor can receive a first measurement of a first capacitance change between a first port and a second port of a device connected to the sensor. The first measurement can be obtained in response to the first port being configured to perform a first function, and in response to the second port being configured to perform a second function. The processor can receive a second measurement of a second capacitance change between the first and second ports. The second measurement can be obtained in response to the first port being configured to perform the second function, and in response to the second port being configured to perform the first function. The processor can determine the likelihood of the occurrence of the anomaly based on the first and second measurements.