Clothes Dryer Pulse-Width Dryness Detection by Resistance Sensing
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Solution Overview
Problem
Automatic dryers face challenges in accurately determining the dryness of clothes, leading to potential over-drying, which can damage delicate items and waste energy, as existing systems rely on humidity monitoring which may not accurately assess the moisture content.
Innovation Solution
A method involving two conductors in the dryer bin that transmit an electric current and use a pulse generator circuit to determine the resistance of the clothes, with a microcontroller analyzing pulses to determine when the clothes are dry, ensuring the drying cycle is terminated appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If humidity monitoring is used to determine dryness, then the drying cycle can be automated, but the measurement precision of moisture content is insufficient
Solution Approach 1:
The patent replaces the mechanical/physical humidity sensing system with an electrical resistance measurement system. Two conductors are positioned in the dryer bin to transmit electric current through the clothes, and a pulse generator circuit measures the resistance. This electrical substitution provides more precise moisture content measurement compared to traditional humidity monitoring of exhaust air.
2Measurement precision
If the drying cycle continues longer to ensure clothes are dry, then measurement precision improves, but loss of energy increases and object-affected harmful factors worsen
Solution Approach 1:
The patent implements a feedback control system where the pulse generator circuit continuously monitors the resistance between conductors, and the microcontroller adjusts the drying cycle based on real-time moisture content measurements. When the resistance indicates sufficient dryness, the system automatically terminates the cycle, preventing energy waste from over-drying while maintaining accurate dryness detection.
3Reliability
If the drying cycle is extended to ensure complete dryness, then reliability of dryness achievement improves, but object-affected harmful factors increase due to damage to delicate clothing
Solution Approach 1:
The patent replaces indirect humidity monitoring with direct electrical resistance measurement through the clothes, providing accurate real-time feedback on actual moisture content. This enables reliable dryness detection without extending the drying cycle unnecessarily, thereby protecting delicate clothing from damage while achieving complete dryness.
4Measurement precision
If resistance-based detection is implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement function needed for dryness detection - the resistance measurement between two conductors. By removing unnecessary components of traditional humidity monitoring systems and focusing solely on electrical resistance measurement, the system achieves high measurement precision while keeping the detection circuit relatively simple and manageable.
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 accurately detects the dryness of clothes, preventing over-drying and energy wastage by reliably terminating the drying cycle when the clothes reach the desired level of dryness, thus extending the dryer's lifespan and protecting delicate items.
Implementation Method 1
the clothing acts as a conductor having a resistance value that varies with the moisture content of the clothes
Data Source
AI summary
A device and method are provided for detecting a root moisture content of clothing in a clothes dryer. The dryer has two conducting bars situated in the dryer bin. A pulse generator circuit is coupled to the conducting bars. A microcontroller is coupled to an output of the pulse generator circuit. The pulse generator circuit generates a pulse when wet clothing contacts the conducting bars in the dryer bin. The microcontroller receives the pulses and counts the pulses that are longer than a threshold length. The microcontroller issues a termination signal based on the number of counted pulses.