Capacitive Humidity Sensor with Extension Conductor for Laundry Drying
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Solution Overview
Problem
Existing laundry drying appliances without humidity measuring arrangements often require users to set drying programs based on duration, leading to inefficient power consumption and suboptimal drying results, as current humidity measurement methods, such as impedance measurement, are not precise, especially when items are placed on support racks or at the bottom of the drum.
Innovation Solution
A laundry appliance equipped with a capacitive humidity measuring arrangement that includes a sensing capacitor with a first and second electrical conductor, where the laundry treatment chamber forms part of the dielectric, and an extension member to extend the first conductor within the drum, allowing for improved penetration and precision in humidity measurement, especially when items are on a support rack or at the bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance measurement method is used for humidity detection, then the measurement can be performed, but the measurement precision is insufficient especially when items are placed on support racks or at the bottom of the drum
Solution Approach 1:
The patent introduces a capacitive sensor as an intermediary measurement device that indirectly measures humidity through capacitance changes rather than direct impedance measurement. The sensor comprises a conductive plate forming one electrode and a reference potential plane forming the other electrode, with the air and items acting as the dielectric medium. This intermediary capacitive measurement approach overcomes the limitations of direct impedance measurement when items are positioned on support racks or at the bottom of the drum.
Solution Approach 2:
The patent replaces the traditional impedance measurement method with a capacitive sensing mechanism. Instead of measuring electrical impedance directly through contact with the items, the system uses a capacitive sensor that detects changes in capacitance caused by humidity-induced changes in the dielectric properties of the air and items. This substitution enables accurate measurement regardless of item position on support racks or drum bottom.
2Ease of operation
If drying program duration is predetermined without humidity measurement, then the appliance operation is simple, but the power consumption is excessive and drying results are suboptimal
Solution Approach 1:
The patent implements a feedback control system where the capacitive humidity sensor continuously monitors the humidity level in the drying chamber and provides real-time information to the control unit. The control unit adjusts the drying program parameters (temperature, airflow, duration) based on the measured humidity, enabling dynamic optimization of power consumption while maintaining simple user operation through automatic program selection and adjustment.
3Measurement precision
If capacitive sensor with extended conductor is used, then the measurement precision for items on support racks is improved, but the device complexity increases
Solution Approach 1:
The patent designs the capacitive sensor with a conductive plate that can serve multiple functions: it acts as one electrode of the capacitor, provides structural support for the sensor assembly, and can be integrated with existing sensor mounting structures in the drying chamber. The reference potential plane is formed using existing conductive surfaces in the chamber, eliminating the need for separate reference electrodes and reducing overall device complexity.
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 provides more accurate humidity measurement, enabling better control of the drying process, reducing power consumption, and improving drying efficiency for items placed on support racks or at the bottom of the drum, which were previously challenging for existing methods.
Implementation Method 1
measuring a capacitance of the capacitor
Implementation Method 2
The permittivity of linen varies considerably according to the humidity thereof
Data Source
AI summary
A laundry appliance having: a treatment chamber; and a humidity measuring arrangement for measuring the humidity of at least one item to be treated. The humidity measuring arrangement has a sensing capacitor and a capacitance sensing unit for measuring a capacitance of the sensing capacitor and obtaining an indication of the humidity of the item to be treated according to the measured capacitance. The sensing capacitor has first and second electrical conductors and a dielectric. A volume of the chamber forms part of the dielectric. The appliance has an extension member configured to be positioned within the chamber for extending the first electrical conductor within the laundry treatment chamber. The extension member has an extension conductor and a coupling conductor, and the extension conductor can be electrically coupled to the first electrical conductor through a capacitive coupling via the coupling electrical conductor.