Hybrid Urinal Sensor Combining Conductivity and Microwave Detection
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Solution Overview
Problem
Conventional sensing technologies for automatic urinal flushing, such as infrared, conductive, and microwave sensors, face issues like material non-detection due to low reflectivity, resource wastage, energy inefficiency, and incorrect flushing timing, which affect user convenience and environmental sustainability.
Innovation Solution
A hidden sensing device combining a conduction sensor for urine detection and a microwave sensor controlled by an MCU, where the conduction sensor informs the MCU to activate the microwave sensor for human presence detection, allowing intelligent water control based on urine conductivity and reducing energy consumption by adjusting detection frequencies and sensor ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional infrared sensor is used for automatic detection, then the urinal can detect human presence, but materials with low reflectivity (dark clothing, hair) cannot be detected reliably
Solution Approach 1:
The patent combines infrared sensor and conductive sensor into a hybrid detection system. The infrared sensor detects human presence generally, while the conductive sensor specifically detects urine presence through conductivity changes in the trap. This merging allows reliable detection across different materials (including dark clothing) while maintaining specificity for urine detection.
Solution Approach 2:
The conductive sensor acts as an intermediary that provides additional detection capability. Instead of relying solely on infrared reflection (which fails for dark materials), the conductive sensor measures electrical conductivity changes in the trap caused by urine presence, providing a complementary detection mechanism that overcomes the limitations of infrared reflection.
2Extent of automation
If conventional infrared sensor flushes after detecting user departure, then the urinal can be flushed automatically, but water is wasted when user stands for extended periods (prostatitis)
Solution Approach 1:
The conductive sensor provides continuous feedback about urine presence in the trap. The system only initiates flushing after confirming both human presence (infrared) and urine presence (conductive sensor). This feedback mechanism prevents premature flushing during extended user presence while maintaining automatic flushing capability when urine is detected and user departs.
Solution Approach 2:
The conductive sensor performs preliminary detection of urine presence before triggering the flushing sequence. By first confirming urine presence through conductivity measurement, the system ensures that flushing is only initiated when necessary, preventing water waste during extended user presence without compromising automatic flushing functionality.
3Ease of manufacture
If conductive sensor is used to detect urine presence, then no inductive window is needed and low-reflectivity materials are detected accurately, but flushing timing becomes inaccurate when user stands for longer periods
Solution Approach 1:
The patent merges conductive sensor (for urine detection) with infrared sensor (for human presence detection). This combination maintains the installation simplicity of conductive sensors while adding the timing accuracy of infrared sensors. The infrared sensor provides departure detection that triggers flushing only when the user actually leaves, preventing premature flushing during extended presence.
4Measurement precision
If microwave sensor with Fourier operation is used, then accurate urine length and user presence can be detected, but energy consumption becomes too high for battery operation
Solution Approach 1:
The patent uses partial action by employing simpler sensors (infrared and conductive) rather than the more complex microwave sensor with Fourier operation. The infrared sensor provides sufficient human presence detection, and the conductive sensor provides adequate urine detection. This partial approach achieves the necessary detection precision while dramatically reducing energy consumption for battery operation.
Solution Approach 2:
The patent replaces the energy-intensive microwave sensor with more energy-efficient battery-operable sensors. The infrared and conductive sensors consume significantly less power, enabling the system to operate reliably on battery power without excessive energy consumption, while still achieving the required detection accuracy for automatic flushing.
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 reliable, energy-efficient, and water-saving automatic flushing by accurately detecting human presence and urine quantity, minimizing false triggers and optimizing water usage while reducing energy expenditure.
Implementation Method 1
conduction sensor technology came out, which can detect the change in conductivity of the water in the trap of the urinal. Based on the different conductivity of urine and tap water, once urine is coming, the electrode of the conduction sensor will touch the urine, and then the detected conductivity will change.
Implementation Method 2
a urinal based on the technology of microwave sensor appeared. It applies Fourier operation to the microwave sensing signals to get the frequency spectrum of the human being and his urine
Data Source
AI summary
A hidden sensing device and its urinal are disclosed. The hidden sensing device, which is attached on some sanitary installations, comprises a conductivity sensor for detecting urine and a Micro-programmed Control Unit (MCU) for processing signals, wherein said conductivity sensor has electrodes extending into urine. The device further includes a microwave sensor controlled by the MCU to detect human's movements. When the conductivity sensor has detected urine, the MCU will turn on the microwave sensor to detect the human's presence or departure.