Apparatus and method for measuring humidity for dryer
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Solution Overview
Problem
Existing dryers face issues with inaccurate humidity sensing due to technical limitations of contact electrode sensors, leading to insufficient or excessive drying of clothes, necessitating a non-contact humidity sensor for improved accuracy and precision.
Innovation Solution
A capacitance measuring sensor with an active shield is used to measure humidity, where a processor applies a second signal with the same waveform and voltage to both the sensor and shield to remove noise and accurately measure humidity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contact electrode sensor is used to sense humidity, then the sensor can detect dry state through contact with cloth, but the measurement accuracy and precision are insufficient to capture the dry state as consumers perceive it
Solution Approach 1:
The patent replaces the contact electrode sensor (mechanical contact-based detection) with a capacitance sensor that measures humidity through electrical field interaction without physical contact. This substitution eliminates the technical limitations of contact sensors while achieving the desired measurement precision for detecting consumer-perceived dry states.
2Measurement precision
If a capacitance sensor is used to measure humidity non-contact, then measurement accuracy is improved, but noise interference from the dryer environment degrades signal quality
Solution Approach 1:
The patent introduces an active shield as an intermediary element between the capacitance sensor and the noisy dryer environment. The shield, driven at the same frequency and voltage as the sensor electrode, acts as a mediator that cancels out parasitic noise and electromagnetic interference, thereby preserving signal quality while maintaining the non-contact measurement advantage.
Solution Approach 2:
The active shield applies a preliminary counteracting signal that is 180° out-of-phase with the parasitic noise, neutralizing the harmful electromagnetic interference before it can corrupt the humidity measurement signal. This preemptive noise cancellation enables accurate capacitance-based humidity sensing in the electrically noisy dryer environment.
3Area of stationary object
If the capacitance sensor is exposed to the entire dryer interior, then the sensing range is maximized, but noise from areas outside the optimal measurement zone increases
Solution Approach 1:
The patent applies local quality by using the active shield to create a localized low-noise measurement zone around the capacitance sensor. The shield confines the electric field and sensing range to a specific area where humidity measurement is most critical, while blocking out parasitic noise from other regions of the dryer interior. This selective localization optimizes the signal-to-noise ratio in the measurement zone.
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 approach minimizes noise interference, allowing for precise humidity measurement and optimal sensing range adjustment, thereby ensuring accurate drying completion time determination.
Implementation Method 1
a capacitance measuring sensor configured to measure an amount of capacitance change that is changed due to humidity of an object to be dried
Implementation Method 2
a transducer comprising at least one planar capacitor with a thin coverlayer of material selected to maximize electric field coupling between cooperating capacitor electrodes
Implementation Method 3
a shield configured to shield noise generated in the dryer; and a processor electrically connected to the capacitance measuring sensor and the shield, wherein the processor is configured to: apply a second signal having the same waveform and the same voltage to the capacitance measuring sensor and the shield
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An apparatus and method for measuring humidity of an object to be dried in a dryer. The apparatus for measuring the humidity for the dryer includes a capacitance measuring sensor configured to measure an amount of capacitance change that is changed due to humidity of an object to be dried, which is put into the dryer; a shield configured to shield noise generated in the dryer; and a processor electrically connected to the capacitance measuring sensor and the shield, wherein the processor is configured to apply a second signal having the same waveform and the same voltage to the capacitance measuring sensor and the shield and acquire the amount of capacitance change, based on the first signal output from the capacitance measuring sensor so as to measure an amount of humidity change of the object to be dried.