Dryness sensing circuit and sensing method of dryness
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Solution Overview
Problem
Existing dryness sensing circuits in clothes dryers face challenges in accurately measuring dryness levels, particularly in the damp and very dry states, due to small variations in voltage signals and high resistance values, which affect measurement accuracy and noise interference.
Innovation Solution
A dryness sensing circuit is designed with a non-inverting amplifier, filter units, and a relay unit to adjust time constants and sensitivity, using high-input impedance operational amplifiers and optical elements to improve resolution and reduce noise, while allowing for voltage level adjustments and cost-effective single power supply operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electrode sensor with two metal plates is used to detect dryness degree, then the dryness level can be categorized into multiple levels, but the voltage signal variation is not great in very dry and damp levels, making it difficult to accurately measure dryness degree
Solution Approach 1:
The patent applies dynamics by making the filter resistor value changeable based on dryness level. The control unit adjusts the filter resistor value to be first value when dryness is first level (very dry), second value when dryness is second level (damp), and third value for intermediate levels. This dynamic adjustment optimizes the time constant for each dryness level, improving measurement precision across all categories while maintaining the multi-level adaptability of the electrode sensor.
2Device complexity
If a filter resistor with fixed value is used in the filter unit, then the circuit structure is simple, but the time constant cannot be optimized for different dryness levels, reducing measurement accuracy
Solution Approach 1:
The patent implements dynamics by replacing the fixed filter resistor with a variable filter resistor that can take different values (first, second, and third values) based on the detected dryness level. The control unit dynamically selects the appropriate resistor value to optimize the time constant for each specific dryness condition, thereby improving measurement accuracy without significantly complicating the overall circuit structure.
Solution Approach 2:
The patent applies parameter changes by modifying the filter resistor value parameter according to the dryness level. When the dryness level changes, the control unit adjusts the filter resistor value accordingly, which changes the time constant parameter of the filter unit. This parameter adaptation allows the system to maintain high measurement precision across varying operating conditions while keeping the circuit structure relatively simple.
3Object-affected harmful factors
If the filter resistor value is increased to improve time constant, then the noise filtering capability is enhanced, but the response time of dryness detection becomes slower
Solution Approach 1:
The patent resolves this contradiction through dynamics by making the filter resistor value adjustable rather than fixed. The control unit selects different resistor values based on the current dryness level: using larger values for better noise filtering when needed, and smaller values for faster response when rapid detection is required. This dynamic adjustment allows the system to optimize the balance between noise filtering and response time according to real-time operating conditions.
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
The solution enhances dryness measurement accuracy across all levels, particularly in the damp state, by optimizing time constants and sensitivity, minimizing noise, and reducing costs through the use of high-input impedance operational amplifiers and single power supply operational amplifiers.
Implementation Method 1
a filter capacitor (Cf) connected between the third node (N3) and the ground
Implementation Method 2
a non-inverting amplifier amplifying the first power supply voltage to output a first output voltage
Implementation Method 3
the electrode sensor 30 senses a dryness degree of clothes by using impedance generated both end of the electrode according to moisture containment of the dry target
Data Source
AI summary
A dryness sensing circuit and a dryness sensing method are provided. The dryness sensing circuit and the dryness sensing method set a time constant of a resistor and capacitor short for liquidity of dryness determination algorithm and minimize a noise effect of a power supply.