Position-Sensitive IR Sensor for Lavatory Faucet Hand Detection
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Solution Overview
Problem
Intensity-based infrared sensors used in electronic faucet activation systems struggle to accurately distinguish between static and dynamic situations near a sink, leading to inconsistent water flow control.
Innovation Solution
A position-sensitive infrared sensor system that detects distance and movement, allowing for more precise control of water flow by calibrating turn-on and turn-off thresholds based on sensor readings, enabling better discrimination between different scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intensity-based IR sensors are used to detect hand presence, then the system can detect the presence of hands or objects under the spout, but the system cannot easily discriminate between various scenarios such as hand entering sink, water stream, hands washing, and static objects
Solution Approach 1:
The patent transitions from intensity-based detection (one-dimensional) to position-sensitive detection (two-dimensional spatial information). The position-sensitive IR sensor detects not only the presence but also the spatial location of reflected IR energy, providing dimensional information that enables discrimination between different scenarios such as hands entering sink versus water stream versus static objects.
Solution Approach 2:
The patent changes the detection parameter from IR energy intensity to IR energy reflection position. This parameter change allows the system to distinguish between different objects and scenarios based on their spatial reflection characteristics rather than just intensity, thereby improving scenario discrimination capability.
2Ease of operation
If the water stream is turned on frequently to accommodate various scenarios, then user convenience is improved, but water waste increases
Solution Approach 1:
The position-sensitive IR sensor provides continuous feedback about the spatial position of objects in the sink area. The controller uses this feedback to make intelligent decisions about when to turn the water stream on or off, turning it on only when hands are detected entering the sink or reaching toward the spout, and turning it off when hands leave the area or when only static objects are present.
Solution Approach 2:
The system turns on the water stream in anticipation when hands enter the sink bowl or reach toward the spout, before the user actually needs water. This preliminary action ensures water is available when needed while avoiding unnecessary activation by waiting for definitive hand-washing intent.
3Loss of substance
If the water stream is turned off quickly to conserve water, then water waste is reduced, but the system may turn off before the user finishes washing
Solution Approach 1:
The system continuously monitors the position-sensitive IR sensor feedback during the water flow period. As long as hands remain in the sink area or reach toward the spout, the feedback maintains the water stream on. The water stream is turned off only when the feedback indicates hands have left the sink area or stopped reaching toward the spout, ensuring the user completes washing without unnecessary interruptions.
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 position-sensitive infrared sensor system improves the accuracy of water flow control by effectively differentiating between various situations, reducing false activations and enabling quicker responses, while also allowing the faucet to remain on longer when objects are in the water stream.
Implementation Method 1
emitting infrared energy from the PSD infrared sensor and toward the stream of liquid; sensing a first position of the infrared energy after the infrared energy has been reflected back to the sensor
Implementation Method 2
sensing a first position of the infrared energy after the infrared energy has been reflected back to the sensor from the stream of liquid
Data Source
AI summary
A method of controlling a flow of liquid includes calibrating a PSD infrared sensor associated with the spout. The calibrating includes turning on the spout to thereby dispense a stream of liquid from the spout and into a stream space; emitting infrared energy from the PSD infrared sensor and toward the stream of liquid; sensing a first position of the infrared energy after the infrared energy has been reflected back to the sensor from the stream of liquid; storing first information based upon the first position of the reflected infrared energy; turning off the spout to thereby inhibit the liquid from being dispensed from the spout; sensing a second position of the infrared energy after the infrared energy has been reflected back to the sensor from an object that is fixed relative to the sensor; and storing second information based upon the second position of the reflected infrared energy. Infrared energy is emitted from the PSD infrared sensor and toward the stream space. A third position of the infrared energy after the infrared energy has been reflected back to the sensor is sensed. The spout is controlled dependent upon the first information, the second information and the third position.