Laundry Dryness Sensing With Reversing Electrode Current
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Solution Overview
Problem
Existing methods for determining the degree of drying of laundry in domestic appliances are hindered by polarization voltage, which falsifies measurements and requires a dead time for correction, preventing rapid or instantaneous determination of dryness.
Innovation Solution
The use of alternating current with periodically changed direction through measuring electrodes in a domestic appliance, eliminating the need for polarization voltage correction and allowing for quick and accurate measurement of conductance or resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct current is used to measure conductance of laundry items, then the measurement can be performed continuously without dead time, but polarization voltage arises that falsifies the measured value
Solution Approach 1:
The patent applies periodic reversal of current direction through the measuring electrodes. Instead of using continuous direct current, the measurement current alternates direction periodically, which prevents the accumulation of polarization voltage at the electrode-laundry interfaces while still allowing continuous measurement without dead time. This resolves the contradiction by enabling both continuous measurement and accurate conductance determination.
2Measurement precision
If polarization voltage correction is performed by determining both conductance and polarization voltage, then measurement accuracy can be maintained, but a dead time of up to 10 seconds must elapse between measurements
Solution Approach 1:
The patent uses periodic current reversal to continuously counteract polarization voltage effects during the measurement process itself, eliminating the need for separate polarization voltage determination steps. This allows continuous measurement without requiring dead time for correction, thus resolving the time-accuracy tradeoff.
Solution Approach 2:
The measurement process maintains continuous current flow through the laundry items without interruption. The periodic reversal of current direction ensures that polarization effects are continuously managed while the measurement proceeds without停顿, eliminating the dead time required in previous methods.
3Measurement precision
If direct current flows through measuring electrodes and laundry items, then chemical reactions and galvanic effects occur causing polarization voltage, but interrupting current flow to eliminate polarization creates measurement delays
Solution Approach 1:
The patent implements periodic reversal of the measurement current direction, which prevents the buildup of polarization voltage and galvanic effects while maintaining continuous current flow. This allows accurate resistance measurements to be taken rapidly without interrupting the drying process, thus improving both measurement accuracy and drying efficiency.
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
Enables precise and rapid determination of the degree of dryness without polarization voltage interference, allowing for real-time monitoring and efficient drying processes.
Implementation Method 1
The degree of dryness of the laundry items can then be deduced from the conductance; the conductance is a measure of the degree of drying. The relationship applies that the lower the conductance or the greater the resistance of the laundry items, the drier the laundry items are.
Implementation Method 2
The degree of dryness of the laundry items can then be deduced from the conductance; the conductance is a measure of the degree of drying. The relationship applies that the lower the conductance or the greater the resistance of the laundry items, the drier the laundry items are.
Implementation Method 3
Due to the galvanic effects, a polarization voltage arises, which depends on the degree of drying of the laundry. This polarization voltage generally falsifies the measured value of the resistance of the laundry items.
Data Source
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AI summary
The invention relates to a household appliance 1 for drying laundry items 3, wherein the momentary level of dryness of the laundry items 3 is to be particularly reliably determined. A measuring device 5 is provided in the household appliance 1 for determining a measurement variable 4, Uw, correlated to the level of dryness of the laundry items 3. The measuring device 5 comprises two measurement electrodes 6, 7 spaced apart from each other and a circuit configuration 8 coupled to the measurement electrodes 6, 7, bringing about a current flow I through the measurement electrodes 6, 7, capturing an electrical laundry voltage drop Uw between the measurement electrodes 6, 7, and deriving the measurement variable 4, Uw, as a function thereof. A direction of the current flow I through the measurement electrodes 6, 7 is changed repeatedly. Galvanic effects at the measurement electrodes 6, 7 are thus prevented.