Appliance with capacitive humidity sensor
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Solution Overview
Problem
Existing laundry drying appliances lack precise humidity measurement methods, particularly when items are dried using an item support rack or located at the bottom portion of the drum, leading to inefficient drying processes and increased power consumption.
Innovation Solution
A capacitive humidity sensing system is implemented, featuring a sensing capacitor with a first and second electrical conductor, where the laundry treatment chamber forms part of the dielectric, and an extension member extends the first conductor within the chamber for improved capacitive coupling, allowing for accurate humidity measurement even when items are on a support rack or at the bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive humidity sensor is used to measure humidity of items located at the bottom portion of the drum or on a support rack, then the measurement precision is improved, but the device complexity increases due to the need for an extension member and capacitive coupling arrangement
Solution Approach 1:
The patent introduces an extension member as an intermediary element that extends the first conductor into the drum chamber. This extension member creates a capacitive coupling between the conductor and items located at the bottom portion or on support racks, enabling humidity measurement without direct contact. The extension member acts as a mediator that transmits the sensing function to distant locations while maintaining electrical isolation through capacitive coupling.
Solution Approach 2:
The patent transitions from direct electrical contact measurement to capacitive coupling measurement, effectively moving the sensing mechanism to a different dimensional approach. By using the extension member to create capacitive fields that penetrate through space to reach items on support racks or at the drum bottom, the system measures humidity in a previously inaccessible dimensional space without physical contact.
2Productivity
If the drying program duration is predetermined without humidity measurement, then the device complexity is reduced, but the productivity decreases due to excessive drying times and power consumption
Solution Approach 1:
The patent implements a feedback mechanism where the capacitive humidity sensor continuously monitors the humidity level of items during the drying process. The measured capacitance value, which correlates with humidity, is fed back to the control system, which then adjusts the drying program duration and parameters accordingly. This feedback loop enables the system to terminate drying as soon as the desired humidity level is achieved, eliminating unnecessary drying time and energy consumption.
Solution Approach 2:
The drying system uses its own operational data (humidity measurement via capacitive sensing) to automatically adjust and optimize its own drying process. The system serves itself by using the humidity information to determine when drying is complete, eliminating the need for external timing references or manual intervention, thereby improving productivity while maintaining reasonable device complexity.
3Measurement precision
If electrical conductivity measurement is used for humidity detection, then the measurement method is simple, but the measurement precision deteriorates when items are not in direct contact with the sensor
Solution Approach 1:
The patent replaces the mechanical contact-based electrical conductivity measurement system with a capacitive coupling-based measurement system. Instead of requiring physical contact between the sensor and the items, the system uses electrical fields that can penetrate through air and dielectric materials to detect humidity. This substitution of the measurement mechanism eliminates the need for mechanical contact while improving measurement precision for items on support racks or at the drum bottom.
Solution Approach 2:
The extension member serves as an intermediary that enables capacitive coupling between the conductor and items without direct contact. The capacitive field created by the extension member penetrates through the air gap and dielectric materials to reach items on support racks or at the drum bottom, allowing humidity measurement without physical contact while maintaining 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
This solution enhances the precision of humidity measurement, enabling more efficient drying processes by adapting the drying program based on real-time humidity levels, reducing energy consumption and improving drying performance for various types of laundry.
Implementation Method 1
measuring a capacitance of the capacitor... determining the humidity of the laundry mass according to the measured capacitance
Implementation Method 2
The permittivity of linen varies considerably according to the humidity thereof... the laundry mass acts as a dielectric
Data Source
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AI summary
A laundry appliance (100) is provided which comprises: a laundry treatment chamber (110) to receive items to be treated; a humidity measuring arrangement (710, 720, 740, 150) for measuring the humidity of at least one item to be treated (730) when located in the laundry treatment chamber (110), said humidity measuring arrangement (710, 720, 740, 150) comprising a sensing capacitor (710) comprising a first electrical conductor (710(1)); an extension member (740) arranged within the laundry treatment chamber for extending the first electrical conductor within the laundry treatment chamber, the extension member comprising an extension electrical conductor (745(1); 745(1)') and a coupling electrical conductor (745(2); 745(2)'), wherein the extension electrical conductor is electrically coupled to the first electrical conductor through a capacitive coupling established by means of the coupling electrical conductor.