Capacitive Sense Array Passive Touch Detection via Noise Signal Coupling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Capacitance sensing systems face errors in touch detection due to noise signals, such as charger noise and display noise, which can result in incorrect touch location, false touches, and missed touches, and existing noise suppression techniques are insufficient, costly, or increase power consumption.

Innovation Solution

The system employs passive touch detection using capacitive coupling of noise signals to detect touches by scanning electrodes along axes, determining signal measurements, and comparing them to thresholds to infer touch locations, and selectively uses either passive touch detection or mutual capacitance touch detection based on noise signal characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If noise suppression techniques are applied to reduce charger noise and display noise, then touch detection accuracy is improved, but system cost and power consumption increase

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent converts noise signals from harmful factors into useful detection signals. By using the noise signal capacitive coupling effect, the system detects touches through the noise signal's capacitive changes rather than traditional active sensing, thereby reducing power consumption while maintaining detection accuracy.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system uses the existing noise signal in the environment to perform touch detection without requiring additional active sensing components. The noise signal serves dual purposes: it is both the disturbance to be suppressed and the signal used for detection, eliminating the need for separate high-power active sensing mechanisms.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If noise suppression techniques are applied to reduce charger noise and display noise, then touch detection accuracy is improved, but system cost increases

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The existing capacitive sense array serves multiple functions: it detects touches using noise signal capacitive coupling and can potentially detect stylus tips using mutual capacitance. This multi-functionality eliminates the need for separate dedicated detection circuits for different touch types, reducing system complexity and cost.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If passive touch detection is used to reduce errors in touch position detection, then false and missed touches are reduced, but the system must selectively use detection modes based on noise characteristics

Engineering Contradiction:

Improvetouch position detection accuracyVSAvoiddetection mode selection complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system dynamically switches between passive touch detection mode (using noise signal capacitive coupling) and mutual capacitance detection mode (for stylus tip detection) based on real-time noise signal characteristics. This dynamic adaptation allows the system to maintain high reliability by selecting the optimal detection mode for current operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from noise signal analysis to determine which detection mode to employ. By continuously monitoring noise signal characteristics, the system can identify when passive detection is appropriate versus when mutual capacitance detection is needed, ensuring accurate touch position detection while managing complexity through intelligent mode selection.

Inventive Principle:

Principle #23Feedback

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 reduces errors in touch position detection, such as false and missed touches, by effectively utilizing noise signals to determine touch locations without increasing power consumption or costs.

Implementation Method 1

A capacitance sensing system may include a processing device and an array of one or more capacitive sense electrodes of a capacitive sense array. The capacitance detected of the capacitive sense array by a processing device may change as a function of the proximity of a touch object to the capacitive sense array.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The system employs passive touch detection using capacitive coupling of noise signals to detect touches

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS12124657B2Passive touch detection for capacitive sense array

Publication Date: 2024.10.22 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

A processing device scans a capacitive sense array to determine a characteristic of a noise signal. A processing device further detects a location of a touch proximate to the capacitive sense array by a passive touch object using a first mode of capacitance touch detection. The first mode of capacitive touch detection uses a capacitive coupling of the noise signal to the capacitive sense array through the passive touch object to detect the touch.