Microwave Oven External Infrared Sensor Temperature Control

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Solution Overview

Problem

Domestic microwave ovens often fail to heat food items to the desired temperature due to users setting inadequate cooking times, and existing temperature-measuring devices are either inconvenient or complex.

Innovation Solution

A microwave oven with an external infrared temperature sensor that measures the initial temperature of food items before heating, allowing users to input the quantity and optionally the target temperature, with the control program automatically determining the appropriate power level and heating time for precise temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an internal temperature-measuring device is used to measure food temperature, then heating precision is improved, but device complexity increases

Engineering Contradiction:
Improvefood temperature measurement accuracyVSAvoidtemperature-measuring device complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The temperature sensor is extracted from the microwave cavity and relocated to the front panel of the microwave oven. This external positioning simplifies the device structure by eliminating the need for complex internal sensor mounting while maintaining measurement capability through non-contact infrared detection.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a mirror system as an intermediary to redirect infrared radiation from the food container to the external temperature sensor. This mediator enables the sensor to measure food temperature without being physically inside the microwave cavity, thus simplifying device complexity while preserving measurement precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If users manually monitor and adjust cooking time based on food temperature, then heating appropriateness is improved, but user time consumption increases

Engineering Contradiction:
Improveheating appropriatenessVSAvoiduser time consumption
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system implements automatic feedback control by continuously monitoring food temperature through the external sensor and adjusting the microwave heating power accordingly. The control program compares the measured temperature with the target temperature and automatically modifies heating parameters, eliminating the need for manual user intervention and ensuring reliable heating results.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The microwave oven performs self-monitoring and self-adjustment of heating parameters through the integrated temperature sensor and control program. The system independently determines when heating is complete and automatically manages the heating process, freeing the user from time-consuming manual monitoring and adjustment tasks.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If the temperature sensor is placed outside the microwave cavity, then device complexity is reduced, but measurement accessibility is improved

Engineering Contradiction:
Improvedevice construction simplicityVSAvoidfood temperature detection capability
Core Design Contradiction:
Ease of manufactureVSDifficulty of detecting and measuring

Solution Approach 1:

The patent transitions the temperature measurement from a three-dimensional internal contact measurement to a two-dimensional external non-contact measurement through the front panel. This dimensional change allows the sensor to detect food temperature from outside the microwave cavity, simplifying construction while maintaining measurement capability through infrared radiation detection.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

A mirror system serves as an intermediary to bridge the gap between the external sensor and the food container. The mirror redirects infrared radiation from the food to the sensor, enabling temperature detection from outside the cavity without compromising measurement accuracy, thus resolving the contradiction between ease of manufacture and measurement capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 simplifies the heating process by minimizing user involvement and ensuring food is heated to a consistent target temperature, particularly effective for baby bottles and other containers, with a simple construction and no need for a temperature sensor within the microwave cavity.

Implementation Method 1

The temperature sensor is suitably an infrared sensor, which determines the temperature of the food item to be heated by means of its emission of infrared radiation.

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 2

a microwave oven which has a comparatively simple construction, and in which an initial temperature of a food item to be heated is determined prior to the heating operation by means of a temperature sensor arranged outside of the cavity of the microwave oven

Methodology Applied
Scientific EffectMicrowave radiation: Microwave Radiation

Implementation Method 3

heating time is determined on the basis of the initial temperature, so that the food item is heated to a desired target temperature

Methodology Applied
Scientific EffectDielectric heating: Dielectric Heating

Data Source

PatentEP1928215B1Microwave oven
Publication Date: 2015.04.01 WHIRLPOOL CORP
  • EP1928215B1 patent drawingFigure 1~2
  • EP1928215B1 patent drawingFigure 3
  • EP1928215B1 patent drawing

AI summary

The present invention provides a microwave oven and a method of operating a microwave oven, which minimises user involvement when heating a food item to a desired target temperature. According to the invention, the initial temperature of the food item is measured prior to the heating process, and the required heating time is determined automatically based on the initial temperature, the target temperature, and the amount of food as entered by the user. In order to heat a food item to a desired target temperature, the user only needs to position a container for temperature measurement and enter the amount of food. In particular, the present invention is preferably adapted for heating of baby food, such as baby milk contained in a baby bottle, and in such case the target temperature is preferably preset to about 37°C.