Automatic Faucet Threshold Control for Detection Stability

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Solution Overview

Problem

Automatic water faucets with person-detecting sensors face challenges in balancing sensitivity and noise reduction, leading to unintended water shutoff during dishwashing and issues with water not shutting off after the task is completed, affecting user usability.

Innovation Solution

The automatic water faucet employs a threshold setting unit that adjusts detection thresholds based on the presence or absence of a detection object, broadening the detection range during use and narrowing it when finished, using hysteresis to prevent unwanted water supply and allow easy resumption without user intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the threshold for the person-detecting sensor is set relatively high to reduce noise influence, then the sensitivity to the detection object decreases and the water faucet shuts off more easily, but this causes unintended water shutoff during dishwashing

Engineering Contradiction:
Improvewater shutoff control reliabilityVSAvoidusability during dishwashing
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the threshold value changeable based on operational state. The control unit dynamically adjusts the threshold between a first threshold value (during active use) and a second threshold value (when inactive), allowing the system to adapt its sensitivity according to whether dishwashing is in progress, thus preventing unintended shutoff while maintaining noise reduction when not in use

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the threshold parameter of the person-detecting sensor based on detection history. When the sensor detects a detection object, the threshold is switched from the first value to the second value, and remains at the second value for a predetermined period even after detection stops, allowing flexible control of the parameter to balance reliability and usability

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the threshold for the person-detecting sensor is set lower to prevent unintended water shutoff, then the detection sensitivity increases, but this causes the water not to shut off even when dishwashing has been finished

Engineering Contradiction:
Improveusability during dishwashingVSAvoidwater shutoff control reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system dynamically adjusts the threshold based on whether a detection object is present. When detection occurs, the lower first threshold value is used to maintain water supply, while when detection stops, the system transitions to the higher second threshold value after a predetermined period, enabling automatic shutoff and preventing continuous water flow

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies preliminary action by setting a predetermined period during which the threshold remains at the second value after detection stops. This preliminary maintenance of the higher threshold prevents immediate re-detection and ensures reliable water shutoff, while still allowing for cases where the user may need to resume washing without manual intervention

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the detection range is broadened to reduce unintended water shutoff, then the likelihood of detection object leaving detection range decreases, but this increases the likelihood of erroneous detection

Engineering Contradiction:
Improvewater supply continuityVSAvoiddetection accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent dynamically controls the detection range by adjusting the threshold parameter. When a detection object is detected, the system switches to the first threshold value that corresponds to a broader detection range, ensuring continuous water supply. When detection stops, it transitions to the second threshold value with a narrower detection range, reducing erroneous detection while maintaining water supply continuity during active use

Inventive Principle:
Principle #15Dynamics

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 approach improves user usability by reducing unintended water shutoff during dishwashing and minimizing erroneous detections, ensuring water supply is controlled effectively and efficiently.

Implementation Method 1

detect light reflected from a detection object such as a user's hand or dishes placed in a sink

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

vary the threshold quantity for the sensor to receive light

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP3054057B1Automatic faucet
Publication Date: 2020.05.06 LIXIL CORP
  • EP3054057B1 patent drawingFigure 1
  • EP3054057B1 patent drawingFigure 2~3
  • EP3054057B1 patent drawingFigure 4

AI summary

An automatic water faucet includes: a water faucet; an imaging unit 26 provided in a water discharge port of the water faucet and that images light reflected from a measure-distance target; a distance measurement unit 32 that measures a distance from the imaging unit 26 to the measure-distance target based on image data captured by the imaging unit 26; a threshold setting unit 35 that sets a threshold for distance; a detection unit 34 that detects the measure-distance target as a detection object if the distance that the distance measurement unit 32 measures is shorter than the threshold set by the threshold setting unit 35; and a water supply control unit 33 that causes the water faucet to discharge water in response to the detection unit 34 detecting a detection object and causes the water faucet to stop supplying water in response to the detection unit 34 not detecting a detection object. The threshold setting unit 35 increases the threshold setting in response to the detection unit 34 detecting a detection object.