Heater Resistance Monitoring for Aerosol Substrate Depletion

Solution Overview

Problem

Existing aerosol-generating systems face challenges in detecting aerosol substrate depletion, leading to overheating and poor aerosol quality, as they require raising the heater temperature to measure electrical resistance changes, which can result in undesirable aerosol properties and user experience.

Innovation Solution

An electrically operated aerosol-generating system with electric circuitry that monitors the first and second derivatives of electrical resistance to detect adverse conditions, such as substrate depletion, allowing for timely power regulation or indication to prevent overheating and ensure aerosol quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the heater temperature is raised to measure electrical resistance changes for detecting substrate depletion, then the detection capability is improved, but the aerosol quality deteriorates and user experience worsens

Engineering Contradiction:

Improvesubstrate depletion detection capabilityVSAvoidaerosol quality degradation

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection of substrate depletion by monitoring the first derivative of electrical resistance with respect to time during normal heating operation, before the heater temperature rises to levels that would degrade aerosol quality. This allows early warning and preventive action to be taken.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the conventional method of detecting substrate depletion through temperature-based resistance measurement with a method based on monitoring the rate of change of electrical resistance (first derivative). This substitution allows detection during normal heating without requiring temperature elevation that would harm aerosol quality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If the heater temperature is raised substantially to detect substrate depletion through electrical resistance changes, then the detection accuracy is improved, but the energy consumption increases and heating time is extended

Engineering Contradiction:

Improvesubstrate depletion detection accuracyVSAvoidheating energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary detection of substrate depletion by monitoring the first derivative of electrical resistance with respect to time during normal heating operation, before the heater temperature rises to levels that would degrade aerosol quality. This allows early warning and preventive action to be taken.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of raising the heater temperature substantially to detect substrate depletion, the system uses a partial approach by monitoring the rate of change of electrical resistance during normal heating. This partial measurement is sufficient to detect depletion without the excessive energy consumption of full temperature elevation.

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If the initial heater resistance is measured to detect substrate depletion, then the detection method is simplified, but the device complexity increases due to additional measurement requirements

Engineering Contradiction:

Improvedetection method simplicityVSAvoidinitial resistance detection requirement

Core Design Contradiction:

Device complexityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces the conventional method of detecting substrate depletion through temperature-based resistance measurement with a method based on monitoring the rate of change of electrical resistance (first derivative). This substitution allows detection during normal heating without requiring temperature elevation that would harm aerosol quality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system continuously monitors the electrical resistance of the heater element and calculates its first derivative with respect to time, providing real-time feedback on substrate depletion status. This feedback mechanism enables dynamic detection without requiring separate initial resistance measurements.

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

Enables rapid detection of substrate depletion before overheating occurs, preventing the creation of poor-quality aerosol and improving user experience by ensuring the system shuts down or alerts the user before aerosol properties degrade.

Implementation Method 1

an electrical heating element arranged to heat the aerosol-forming substrate to a target temperature

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

monitors a first derivative of electrical resistance of the heating element with respect to time

Methodology Applied

Scientific EffectElectrical resistance temperature dependence: Electrical Resistance

Data Source

PatentUS11864596B2Methods for detecting heater conditions in an aerosol-generating system

Publication Date: 2024.01.09 PHILIP MORRIS PRODUCTS SA

AI summary

An electrically operated aerosol-generating system is provided, including: a heating element configured to heat an aerosol-forming substrate proximate to the heating element; a power supply; and electric circuitry in communication with the element and the power supply, and configured to regulate the supply of power during a plurality of discrete heating cycles in response to user inputs, determine a maximum electrical resistance of the heating element during each heating cycle, calculate a rolling average value of the resistance for n preceding heating cycles, n being an integer greater than 1, compare the resistance with the calculated value, determine an adverse condition when the resistance is greater than the calculated value by more than a threshold value, the threshold value being stored in the memory, and control the power supplied based on whether there is the adverse condition or to provide an indication based on whether there is the adverse condition.