Dual-Sensor Airflow Switch Circuit for Electronic Cigarette Power Control

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Solution Overview

Problem

Existing electronic cigarettes fail to accurately detect and adjust the user's smoking process due to limitations in current switch mechanisms, such as microphone switches and key buttons, which do not reflect the true smoking action or adjust atomizing power effectively.

Innovation Solution

A switch control circuit with a sensing circuit comprising a heating part and two sensors, a controller, and a power supply system that detects temperature changes in airflow to determine voltage differentials, allowing for precise adjustment of atomizing power based on airflow variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a microphone switch is used to detect smoking actions, then the electronic cigarette can identify whether a smoking action exists, but it cannot measure the degree of capacitance change to reflect the true smoking process

Engineering Contradiction:
Improvesmoking action detection accuracyVSAvoidcapacitance change magnitude
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent divides the single sensor detection into two separate sensors (first sensor and second sensor) positioned at different locations. This segmentation allows the system to capture different aspects of the smoking action and compare them, thereby recovering the lost information about capacitance change magnitude that a single microphone switch cannot provide.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces temperature as an intermediary parameter between the capacitance change and the final detection result. By measuring temperature changes at two different points and calculating the voltage differential, the system indirectly captures the magnitude of the smoking action that the microphone switch alone cannot measure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a key button is used to control the electronic cigarette, then the user can manually initiate or adjust atomizing power, but it cannot automatically reflect the true smoking process

Engineering Contradiction:
Improvemanual controlVSAvoidsmoking action detection
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system uses the user's own smoking action (airflow) to automatically control the atomizing process. The two sensors detect the temperature changes caused by the user's breath, and the controller automatically adjusts the atomizing power based on the voltage differential, eliminating the need for manual key button operation while accurately reflecting the true smoking process.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent implements a feedback loop where the sensors continuously monitor the user's breathing pattern, the controller processes the voltage differential signal, and the atomizing power is adjusted in real-time based on this feedback. This closed-loop system automatically adapts to the user's smoking intensity without requiring manual intervention.

Inventive Principle:
Principle #23Feedback

3Device complexity

If traditional switch mechanisms are used, then the structure is simple, but condensation issues occur around the switch mechanisms

Engineering Contradiction:
Improveswitch mechanism structureVSAvoidcondensation
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical key button or microphone switch with a non-contact thermal sensing system. The two temperature sensors detect the user's breath through thermal changes in the air flow, eliminating the need for physical switches that are prone to condensation. This substitution removes the harmful condensation effect while maintaining detection functionality.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If the voltage differential is used to control atomizing power, then the atomizing power can be adjusted according to smoking intensity, but the system complexity increases

Engineering Contradiction:
Improveatomizing power adjustmentVSAvoidsensing circuit
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the two temperature sensors and their signal processing into an integrated sensing circuit that directly outputs the voltage differential. By merging the detection and processing functions into a unified circuit, the system achieves adaptable atomizing power control based on smoking intensity while minimizing the increase in overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

The solution accurately mimics the user's smoking action, enhancing the smoking experience by real-time adjustment of atomizing power, improving safety and reliability by avoiding condensation issues around traditional switch mechanisms.

Implementation Method 1

the heating part is disposed between the first sensor and the second sensor for conveying heat to the first sensor and the second sensor

Methodology Applied
Scientific EffectHeat convection: Convection

Implementation Method 2

the first sensor is configured for detecting a first voltage generated by change of temperatures when an air flow is flowing over the first sensor

Methodology Applied
Scientific EffectTemperature change detection: Temperature Gradient

Data Source

PatentEP3572775B1Switch control circuit and switch control method for electronic cigarette and electronic cigarette
Publication Date: 2025.04.02 SHENZHEN FIRST UNION TECH CO LTD
  • EP3572775B1 patent drawingFigure 1
  • EP3572775B1 patent drawingFigure 2
  • EP3572775B1 patent drawingFigure 3

AI summary

A switch control circuit and method for an electronic cigarette and the electronic cigarette are disclosed, the circuit includes a sensing circuit including a first sensor, a second sensor and a heating part disposed between the first sensor and the second sensor for conveying heat to the first sensor and the second sensor; the first sensor is for detecting a first voltage generated by change of temperatures when an air flow is flowing over the first sensor; the second sensor is configured for detecting a second voltage generated by change of temperatures when the air flow is flowing over the second sensor; and a controller coupled with a sensing circuit and stores a preset voltage threshold for receiving the first voltage and the second voltage, comparing a voltage differential of the first voltage and the second voltage with the preset voltage threshold, and outputting corresponding action signals based on comparison.