Clothes Dryer Dryness Detection Using a Thermopile Array Sensor
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Solution Overview
Problem
Traditional dryers face issues with inaccurate determination of clothing dryness due to sensor pollution, poor contact, and inability to differentiate between various clothing types, leading to energy wastage and inconvenience.
Innovation Solution
A dryer equipped with a thermopile array sensor that senses temperature distribution and average temperature of clothing without contact, using a signal processor to determine complete dryness and control the drying schedule.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a resistive humidity sensor is disposed within the cylinder to sense clothing humidity, then the drying schedule can be controlled automatically, but the sensor is apt to be polluted by cotton and cannot contact the clothing completely, resulting in false signals and energy waste
Solution Approach 1:
The patent replaces the mechanical contact-based resistive humidity sensor with a non-contact microwave sensor system. The microwave sensor transmits microwave signals through the cylinder wall to detect water content in clothing without physical contact, eliminating pollution issues and false signals while maintaining automatic drying control.
Solution Approach 2:
The patent introduces microwave signals as an intermediary to detect clothing moisture content. Instead of direct sensor-clothing contact, the microwave signals pass through the cylinder wall and interact with the clothing's water molecules, providing accurate detection without contamination.
2Reliability
If the drying time is extended to ensure complete drying, then all clothing can be dried thoroughly, but energy is wasted due to excessive drying
Solution Approach 1:
The patent implements a feedback control system where the microwave sensor continuously monitors clothing moisture content during drying. The controller receives real-time moisture data and dynamically adjusts the drying schedule, stopping the heater when moisture reaches a preset threshold, thereby preventing energy waste from over-drying while ensuring complete drying.
Solution Approach 2:
The drying system uses its own sensor data to automatically determine when drying is complete, eliminating the need for user estimation or extended fixed-time drying cycles. The system serves itself by making real-time decisions based on actual clothing moisture conditions.
3Measurement precision
If a plurality of resistive humidity sensors are disposed to improve detection accuracy, then more clothing areas can be monitored, but the device complexity increases and false signals still occur
Solution Approach 1:
The patent uses a single microwave sensor that can detect moisture content throughout the entire drum volume by transmitting signals through the cylinder wall. This single sensor performs the function that would otherwise require multiple contact sensors, reducing device complexity while maintaining or improving measurement precision.
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
Accurately determines clothing dryness, avoiding false signals and energy wastage, and enabling automatic shutdown of the drying process, thus optimizing energy consumption.
Implementation Method 1
The thermopile array sensor is used to sense an infrared light radiated from the clothing and output a sensing signal
Data Source
AI summary
A dryer includes a cylinder, a heater, a motor, a temperature sensor and a controller. The heater heats air and delivers the heated air into the cylinder. The motor is used to drive the cylinder to rotate. The temperature sensor includes a thermopile array sensor and a signal processor. The thermopile array sensor is used to sense an infrared light radiated from clothing and output a sensing signal. The signal processor is used to process the sensing signal to obtain at least one of a temperature distribution uniformity and an average temperature of the clothing, and output a control signal according to the at least one of the temperature distribution uniformity and the average temperature of the clothing. The controller determines to stop the drying schedule according to the control signal. The above-mentioned dryer can stop the drying schedule automatically, so as to save energy.