Induction Cooker Infrared Sensor Differential Temperature Control
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Solution Overview
Problem
Existing induction heating cookers face challenges in accurately controlling temperature due to variations in reflectivity and emissivity of heated objects, leading to errors in temperature measurement and susceptibility to disturbance light and stains, which complicates the configuration and reduces accuracy.
Innovation Solution
An induction heating cooker with a simplified configuration using an infrared sensor that outputs a detection signal with a constant magnitude at lower temperatures and exponentially increasing magnitude at higher temperatures, featuring a storage unit to measure and store initial detection values, allowing for accurate temperature control by reducing the output or stopping heating when a predetermined increase in signal is reached, and incorporating a filter to minimize disturbance light influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the infrared sensor measures the absolute value of energy amount to calculate temperature, then temperature detection is achieved, but measurement precision deteriorates due to reflectivity differences of heated objects
Solution Approach 1:
The patent changes the detection parameter from absolute energy amount to differential energy amount (change量). By measuring the change in infrared energy before and after heating starts, the system eliminates the influence of object reflectivity differences, achieving consistent temperature measurement across different heated objects.
Solution Approach 2:
The system performs preliminary measurement of the initial infrared energy state before heating begins. This preliminary action establishes a baseline that is then used to calculate the differential change, allowing the system to compensate for variations in object properties and achieve accurate temperature measurement.
2Measurement precision
If two infrared detection elements are used to measure temperature without emissivity influence, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
Instead of using multiple detection elements with different spectral responses, the patent uses a single infrared detection element and changes the measurement parameter to differential energy change. This approach achieves emissivity-independent temperature measurement while maintaining simple device configuration.
Solution Approach 2:
The patent extracts only the necessary function of temperature measurement from complex multi-element systems. By using a single detection element and focusing on the differential change in energy rather than absolute values, the system achieves accurate temperature measurement without the complexity of multiple sensors.
3Reliability
If the infrared light incident region or heated object surface becomes stained, then measurement reliability deteriorates, but no simple solution exists to maintain accuracy
Solution Approach 1:
The patent measures the initial infrared energy state before heating and uses the differential change as the measurement parameter. This approach makes the measurement immune to stains on the incident region or object surface, as stains affect both the initial and subsequent measurements equally, canceling out in the differential calculation.
4Measurement precision
If disturbance light enters the infrared sensor, then measurement precision deteriorates, but adding filters increases device complexity
Solution Approach 1:
The patent uses differential measurement of infrared energy change rather than absolute energy measurement. This parameter change makes the system inherently resistant to disturbance light, as disturbance light contributes equally to both the initial and subsequent measurements, canceling out in the differential calculation without requiring additional filters.
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 enables accurate and responsive temperature control of heated objects with reduced influence from reflectivity and emissivity variations, and disturbance light, ensuring safe and efficient cooking performance.
Implementation Method 1
an infrared sensor that includes an infrared detection element provided on a lower side of the top plate to detect an amount of infrared light radiated from the heated object
Implementation Method 2
a heating coil operable to perform induction heating of an object to be heated placed on the top plate
Implementation Method 3
an induction heating cooker for performing induction heating of an object to be heated such as a pan or a flying pan using an electromagnetic induction heating coil
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An infrared sensor 26 includes an infrared detection element 26a which is provided on a lower side of a top plate 2 to detect an amount of infrared light radiated from a heated object 20 and an amplifier 26b operable to amplify a signal detected by the infrared detection element 26a. The infrared sensor 26 outputs an initial detection value having a substantially constant magnitude with respect to the temperature of the heated object 20 when the temperature of the heated object 20 is lower than a detection lower limit temperature, and outputs a detection signal having magnitude and rate of increase which become larger as the temperature of the heated object 20 becomes higher in the vicinity of a control temperature range in which the control unit 29 controls the output of the induction heating coils 21a and 21b to perform temperature control of the heated object 20. The control unit 29 includes a storage unit 29a operable to measure and store the initial detection value, and reduces the output of the induction heating coils 21a and 21b or stops the heating when an increased amount of the output value of the infrared sensor 26 with respect to the initial detection value stored in the storage unit 29a becomes greater than or equal to a predetermined value.