Dual-Sensor Capacitance Module for Temperature-Stable Wear Detection

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Solution Overview

Problem

Capacitance detection in electronic devices is affected by temperature changes, leading to incorrect detection of device wear or removal states, as temperature drift can mimic or overpower the changes caused by human proximity.

Innovation Solution

A capacitance detection module with a first and second sensing unit, where the second sensing unit does not directly touch human skin, allowing the detecting circuit to differentiate between capacitance changes caused by temperature and human touch, thereby accurately determining the device's wear state by analyzing the capacitance values of both units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single sensing unit is used for capacitance detection, then the device structure is simple, but the detection accuracy is poor due to temperature drift affecting the capacitance value

Engineering Contradiction:

Improvesensing unit structureVSAvoidcapacitance detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The sensing module is divided into two independent sensing units: a first sensing unit that detects both temperature drift and human touch effects, and a second sensing unit that detects only temperature drift. By segmenting the sensing function, the patent enables differential measurement to eliminate temperature drift interference while maintaining detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second sensing unit acts as an intermediary that measures only the temperature drift component. Its output serves as a reference signal that is subtracted from the first sensing unit's output, thereby mediating the elimination of temperature drift effects and isolating the human touch detection signal.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If capacitance detection is performed without temperature compensation, then the detection circuit is simple, but the reliability is poor due to false detection caused by temperature drift

Engineering Contradiction:

Improvedetection circuitVSAvoidwear state detection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The detection circuit uses the output from the second sensing unit as feedback to compensate for temperature drift effects. The capacitance value from the second sensing unit is subtracted from the first sensing unit's capacitance value, creating a temperature-compensated detection signal that improves reliability by eliminating false detections.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If only one sensing unit is used, then the manufacturing cost is low, but the detection stability is poor under temperature changes

Engineering Contradiction:

Improvemanufacturing costVSAvoidcapacitance value stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the operational parameters by measuring capacitance values from two different sensing units under the same temperature conditions. By subtracting the capacitance difference between the two units, the system compensates for temperature-induced parameter changes and maintains stable detection performance.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively mitigates the impact of temperature on capacitance detection, enabling accurate determination of device wear or removal states by isolating the effects of temperature and human proximity, thus improving the reliability of capacitance-based sensing systems.

Implementation Method 1

the self-capacitance between them also changes. The self-capacitance refers to the capacitance value between the sensor 13 and the ground unit 14

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the temperature may cause the dielectric layer 15 and the sensor 13 on the sensing module 11 to expand or contract. The effect of temperature on the capacitance value could be called temperature drift

Methodology Applied

Scientific EffectTemperature drift: Thermal Expansion

Data Source

PatentUS11448675B2Capacitance detection module, method and electronic device

Publication Date: 2022.09.20 SHENZHEN GOODIX TECH CO LTD

AI summary

The present application provides a capacitance detection module, a method and an electronic device, including: a sensing module and detecting circuit; a first sensing unit is disposed on the first surface of the sensing module, and a second sensing unit is disposed on the second surface of the sensing module; the first sensing unit and the second sensing unit are respectively connected to the detecting circuit; the detecting circuit is configured to determine, according to the capacitance value of the first sensing unit and the capacitance value of the second sensing unit, the wearing state of the user to the device having the capacitance detection module. Thereby the problem that the capacitance detection is affected by temperature is avoided.