Dryer and controlling method thereof
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Solution Overview
Problem
Conventional dryers face inaccuracies in measuring drying rates due to impedance variations from different laundry types, risk of user shock from electrode sensors, and lack of malfunction detection, which can lead to overheating and potential fires.
Innovation Solution
A control method for dryers that uses a sensing circuit outputting pulse signals based on laundry contact, with a microprocessor determining drying rates and malfunctions, featuring a comparator and photocoupler to isolate high-power circuits and prevent user shock, and includes predetermined pulse counts for determining drying completion and malfunction detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a direct contact-type electrode sensor is used to measure drying rate, then the sensor can detect moisture content through impedance, but the measurement accuracy deteriorates due to impedance variation according to various kinds of laundry
Solution Approach 1:
The patent introduces a pulse signal generation circuit as an intermediary between the electrode sensor and the microcontroller. This circuit converts the continuous impedance signal into discrete pulse signals whose frequency corresponds to the drying rate, eliminating the direct impedance measurement and its associated accuracy issues with different laundry types.
Solution Approach 2:
The patent replaces the direct electrical impedance measurement system with a pulse frequency-based system. Instead of measuring impedance directly (which varies with laundry type), the system generates pulses at frequencies proportional to the drying rate, providing a more reliable and consistent measurement method.
2Ease of operation
If the electrode sensor is connected to the inverter circuit ground, then the sensing circuit can operate, but high voltage is supplied to the sensing circuit causing user shock risk
Solution Approach 1:
The patent segments the grounding system into two separate grounds: one for the high-power inverter circuit and another for the low-power sensing circuit. This segmentation isolates the sensing circuit from high voltage, eliminating the shock risk while maintaining proper operation of both circuits.
Solution Approach 2:
The patent introduces a separate ground reference as an intermediary for the sensing circuit, preventing direct connection between the high-voltage inverter ground and the low-voltage sensor ground. This intermediary ground structure maintains circuit operation while protecting users from electric shock.
3Device complexity
If no auxiliary malfunction sensing means is provided, then the device complexity is reduced, but the reliability deteriorates due to inability to detect malfunctions like motor lock or belt cutoff
Solution Approach 1:
The patent makes the pulse signal generation circuit multi-functional: it serves both to indicate drying rate (through pulse frequency) and to detect malfunctions (through pulse absence). This universal approach provides malfunction detection without adding separate auxiliary sensing means, maintaining simplicity while enhancing reliability.
Solution Approach 2:
The existing pulse signal generation circuit performs dual duties: measuring drying rate and detecting malfunctions. The system uses its own operational signals to monitor its own health, eliminating the need for separate malfunction detection hardware and achieving self-diagnostic capability.
4Measurement precision
If auxiliary accurate sensor and detection circuit are provided to improve drying rate measurement, then measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent designs the pulse signal generation circuit to serve multiple functions: it provides accurate drying rate measurement through pulse frequency while also enabling malfunction detection through pulse presence/absence monitoring. This multi-functionality achieves high measurement precision without increasing device complexity.
Solution Approach 2:
The system uses the same pulse signal circuit for both measurement and self-diagnosis functions. The circuit measures drying rate accurately and simultaneously monitors its own operational status, eliminating the need for separate auxiliary sensors and keeping the system simple while achieving high 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 provides accurate drying rate determination, reduces user safety risks, and enhances reliability by preventing overheating and potential fires through separate power circuits and effective malfunction detection.
Implementation Method 1
The electrode sensor 30 is formed of two metal plate that are parallel to sense a drying rate of fabric by using impedence, such that the detected drying rate is outputted as a voltage signal. The impedence is produced at both opposite ends of an electrode based on moisture content when the laundry contacts with both metal plates.
Implementation Method 2
a sensing circuit that outputs a pulse signal based on contact with the laundry; and a micom that controls the dryer
Data Source
AI summary
The present invention relates to a dryer and a controlling method of a dryer, which can sense whether there is a malfunction or can precisely sense a drying rate of laundry. A dryer comprising a drum that laundry is stored in and a heater that supplies hot air to the drum, the dryer includes a sensing circuit that outputs a pulse signal based on contact with the laundry; and a micom that controls the dryer, wherein the micom determines a drying rate of the laundry or whether there is a malfunction in the dryer based on the pulse signal outputted from the sensing circuit.