Water quality sensor
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Solution Overview
Problem
Existing turbidity sensors in washing appliances suffer from reduced resolution and misjudgment in turbidity ranges of 2000-4000 NTU, leading to incorrect wash cycle selection, resulting in wastage of water and electricity or inadequate cleaning.
Innovation Solution
A water quality sensor with a dual light path system, utilizing a light emitting element and two light receiving elements on opposite surfaces of a circuit board, where one path transmits light directly and the other receives scattered light, enabling accurate turbidity calculation through inverse and proportional voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a light transmission structure with one light emitting element and one light receiving element is used, then the device complexity is reduced and manufacturing cost is lowered, but the measurement precision deteriorates in turbidity ranges of 2000-4000 NTU due to reduced voltage difference resolution
Solution Approach 1:
The sensing module is segmented into two independent detection paths: a light transmission path with a first light receiving element and a scattered light path with a second light receiving element. Each path uses the same light emitting element but detects different light properties, allowing the system to overcome the limitations of a single detection method across different turbidity ranges
Solution Approach 2:
The light emitting element serves multiple functions by being shared between two different detection paths. The same light source is used for both transmission detection and scattered light detection, making the component universal and avoiding the need for separate light sources for each detection method
2Device complexity
If the light emitting element and light receiving element are positioned on the same surface of the circuit board, then the device complexity is reduced, but the measurement precision deteriorates because scattered light cannot be effectively detected
Solution Approach 1:
The second light receiving element is positioned on the opposite surface of the circuit board relative to the light emitting element, creating a three-dimensional detection geometry. This dimensional change allows the sensor to detect scattered light at different angles and effectively measure turbidity through multiple optical paths
3Device complexity
If only one light receiving element is used to reduce device complexity, then the manufacturing cost is lowered, but the reliability deteriorates due to misjudgment in high turbidity ranges leading to incorrect wash cycle selection
Solution Approach 1:
The system uses feedback from two different detection paths to make a reliable determination of wash cycle requirements. By comparing results from both the light transmission path and scattered light path, the system can accurately determine when to switch between different light receiving elements, ensuring reliable wash cycle selection across all turbidity ranges
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
Enhances turbidity measurement accuracy, preventing incorrect wash cycle selection and optimizing water and energy usage by distinguishing between different turbidity levels effectively.
Implementation Method 1
the light emitting element and the first light receiving element belong to a light transmission structure, so that when washing water flows through a first light path, the output voltage difference of the first light receiving element is inversely proportional to the turbidity
Implementation Method 2
the second light receiving element is provided on an opposing second surface of the circuit board and used to receive the scattered light of the impurity particles in the water flow irradiated by the light signal on the first light path
Data Source
AI summary
A water quality sensor includes a housing that defining a channel between a first light-transmission portion and a second light-transmission portion thereof, and a sensing module including a circuit board mounted in the housing, a light emitting element provided on a first surface of the circuit board and disposed in the first light-transmission portion, a first light receiving element provided on the first surface of the circuit board and disposed in the second light-transmission portion and a second light receiving element provided on an opposing second surface of the circuit board. The light emitting element transmits light signal to the first light receiving element through the channel to form a first light path. The second light receiving element receives scattered light of impurity particles in the water flow irradiated by the light signal on the first light path and forms a second light path.