Washing Machine Reed Sensor Circuit for Door Magnetization Errors
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Solution Overview
Problem
Existing washing machine sensors face reliability issues due to prolonged magnetization when the door is closed, leading to potential errors in detecting door opening/closing states, which can affect the operation of the drum and overall washing machine functionality.
Innovation Solution
A plurality of reed sensors are strategically disposed to react to a single magnet, connected in series, and mounted on a circuit board with varying working distances to ensure simultaneous and accurate detection of door states, preventing errors and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single reed sensor is used to detect door state, then the device complexity is low, but the reliability of detection is insufficient
Solution Approach 1:
The patent divides the detection function into multiple independent reed sensors (first reed sensor and second reed sensor) positioned at different locations. Each sensor independently detects the door state, and their outputs are logically combined to determine the final door state, thereby improving reliability through distributed detection points
Solution Approach 2:
The patent combines the detection results of multiple reed sensors through logical operations in the control unit. The control unit processes signals from both sensors and determines door state based on the combined output, merging individual sensor data into a unified reliable detection result
2Reliability
If multiple reed sensors are positioned at different distances from the magnet, then the detection coverage is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent assigns different functional roles to sensors at different positions: the first reed sensor is positioned closer to the magnet for primary detection, while the second reed sensor is positioned farther away to detect door opening states. Each sensor's position is optimized for its specific detection function, allowing varied positioning without requiring uniform high-precision placement
Solution Approach 2:
The patent incorporates a magnetic shield between the magnet and the second reed sensor to control magnetic field distribution. This shield prevents excessive magnetic field strength from affecting the second sensor, allowing it to be positioned farther away while maintaining reliable detection, thus reducing positioning precision requirements
3Measurement precision
If reed sensors are positioned closer to the magnet, then the detection sensitivity is high, but the magnetization duration is prolonged causing errors
Solution Approach 1:
The patent uses the periodic opening and closing of the door to modulate the magnetic field exposure of the reed sensors. When the door closes, the magnet approaches the sensors periodically, generating detectable signal changes. This periodic action allows sensitive detection while the transient nature of magnetization prevents prolonged exposure errors
Solution Approach 2:
The magnetic shield is positioned to protect the second reed sensor from excessive magnetic field strength. By attenuating the magnetic field before it reaches the second sensor, the shield prevents prolonged or excessive magnetization that could cause detection errors, while still allowing the first sensor to operate at optimal sensitivity
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 ensures reliable and simultaneous detection of door opening/closing states, preventing errors and improving the washing machine's operational control by using multiple reed sensors connected in series to react to a single magnet, thus enhancing the reliability and efficiency of the door state detection system.
Implementation Method 1
at least one magnet provided in one of the door or the main body; and a plurality of reed sensors provided in the other of the door or the main body and configured to react to the at least one magnet
Data Source
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AI summary
A distance sensor and a washing machine including the distance sensor are provided. The washing machine may include a main body (50) having a laundry loading hole formed therein, a door (30) coupled to the main body (50), at a position corresponding to the laundry loading hole, and a plurality of reed sensors (100, 200). The door (30) may include a magnet (37) disposed therein. The plurality of reed sensors (100, 200) provided in the main body (50) and react to the magnet (37) provided in the door (30) to determine an open/closed state of the door (30).