Knock detection device and household appliance including the same
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Solution Overview
Problem
Existing knock detection systems for household appliances are unreliable due to interference from vibrations and noises, leading to false triggering and potential damage to the appliance.
Innovation Solution
A knock detection device comprising a proximity sensor, a sound sensor, and a signal processing unit, which uses a support structure to minimize interference and differentiate between user-generated knocks and appliance vibrations, allowing for reliable detection and response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sound sensor is used to detect knocking sounds, then the door can be opened by knocking, but vibrations and noises during appliance operation cause false triggering and unreliable detection
Solution Approach 1:
A proximity sensor is introduced as an intermediary device to detect whether the user is in proximity to the appliance before the sound sensor processes knocking sounds. This intermediary detection mechanism filters out false triggers from internal vibrations by verifying user presence first, thereby improving reliability while maintaining ease of operation.
2Measurement precision
If the sound sensor is placed close to the panel for sensitive detection, then knocking can be detected accurately, but the sensor is more affected by humidity and direct contact forces
Solution Approach 1:
The proximity sensor acts as a mediator that enables the sound sensor to be positioned optimally without direct contact with the panel. By detecting user proximity wirelessly, the system maintains detection sensitivity while eliminating harmful effects of humidity and contact forces on the sensor.
3Reliability
If a proximity sensor is added to filter out false triggers, then detection reliability improves, but device complexity increases
Solution Approach 1:
The proximity sensor and sound sensor are merged into an integrated detection system where the proximity sensor's output directly controls the signal processing of the sound sensor. This combination achieves improved reliability through coordinated detection while minimizing complexity by using a unified control architecture rather than separate independent systems.
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 provides a highly sensitive and reliable knock detection system that effectively avoids false triggering, ensuring accurate user input recognition and maintaining appliance functionality.
Implementation Method 1
a proximity sensor (1), at least one sound sensor (2)
Implementation Method 2
the sound sensor detects sound waves caused by knocking, and the sound waves cause the sound sensor to generate signals
Data Source
AI summary
A knock detection device includes a proximity sensor, at least one sound sensor, and a signal processing unit. The proximity sensor and the sound sensor are respectively electrically connected to the signal processing unit. The signal processing unit receives and/or processes the signal of the sound sensor according to the signal of the proximity sensor. A household appliance includes the knock detection device. The knock detection device is disposed inside the household appliance on the back side of a panel provided for knocking by a user.