Capacitance Sensor Noise Measurement Frequency Selection

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Solution Overview

Problem

Capacitance sensors in devices like laptops and touchscreen computers face challenges in accurately detecting user input due to electrical noise affecting the sense electrode.

Innovation Solution

The method involves taking noise measurements at different frequencies using a dedicated sense electrode and determining which frequency has lower noise, then taking capacitance measurements at that frequency to improve detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a capacitance sensor uses a sense electrode to detect user input, then the detection capability is enabled, but electrical noise on the sense electrode decreases measurement accuracy and precision

Engineering Contradiction:

Improvecapacitance measurement accuracyVSAvoidelectrical noise interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic action by taking multiple noise measurements at different frequencies (first frequency and second frequency) and using periodic sampling to capture noise characteristics. The system periodically switches between different measurement frequencies to identify and avoid noisy frequency bands, thereby improving capacitance measurement accuracy in noisy environments.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent changes the frequency parameter of the measurement signal to resolve noise interference. By measuring noise at different frequencies and selecting the frequency with lower noise for capacitance measurement, the system dynamically adjusts the operating frequency parameter to optimize measurement quality and reduce the harmful effects of electrical noise.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple noise measurements are taken at different frequencies, then noise reduction is achieved, but measurement time and processing complexity increase

Engineering Contradiction:

Improvenoise reduction qualityVSAvoidmeasurement cycle duration

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by taking noise measurements at different frequencies before performing the actual capacitance measurement. This preliminary noise characterization allows the system to pre-determine the optimal measurement frequency, preventing the need for repeated measurements and reducing overall measurement time while maintaining high precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system performs self-service by automatically selecting the optimal measurement frequency based on the noise characteristics it measures itself. The capacitance sensor autonomously evaluates noise at different frequencies and chooses the best frequency for subsequent measurements without external intervention, streamlining the process and reducing time loss.

Inventive Principle:

Principle #25Self-service

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 noise interference in capacitance measurements, enhancing the accuracy and precision of user input detection in capacitance sensors.

Implementation Method 1

A capacitance sensor generally detects input by applying a voltage to a transmit electrode in the capacitance sensor and measuring the change in the electric field on a sense electrode in the capacitance sensor

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

a capacitance sensor may be used to detect user input... measuring the change in the electric field... The sense electrode may be susceptible to electrical noise

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS12287940B2Noise measurements with a capacitance sensor

Publication Date: 2025.04.29 CIRQUE CORP

AI summary

Using a capacitance sensor may include taking a first noise measurement by imposing a first signal on a capacitance sensor, the first signal having a first frequency; taking a second noise measurement by imposing a second signal on the capacitance sensor, the second signal having a second frequency different than the first frequency; determining the measurement with the lower amount of noise between the first noise measurement and the second noise measurement; and taking a capacitance measurement by imposing a third signal on the capacitance sensor, the third signal having either the first frequency or the second frequency based, at least in part, on the frequency of the measurement with the lower amount of noise.