Optical Turbidity Sensor Light Path for Foam-Resistant Washing
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Solution Overview
Problem
Optical sensors used in washing machines and dishwashers as turbidity sensors are susceptible to faults due to temporary decreases in sensor output signals caused by foreign particles and foam bubbles in the washing water, which result in noisy readings.
Innovation Solution
The optical sensor design features a light measurement path with a minimum cross-sectional area of 0.9 mm^2 between reflection surfaces, ensuring that light beams undergo total reflection, reducing the disturbing influence of particles and foam bubbles, and includes a sealed housing structure to protect electronic components from washing water, ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the light beam cross-sectional area is reduced to minimize sensor size, then the sensor compactness is improved, but the sensor output signal becomes more susceptible to noise from particles and foam bubbles
Solution Approach 1:
The patent specifies a minimum light beam cross-sectional area of 0.9 mm² as a critical parameter threshold. By maintaining the light beam area above this threshold, the sensor achieves adequate signal stability while keeping the overall sensor design compact. This parameter-based approach resolves the contradiction by establishing a quantitative boundary that prevents excessive noise susceptibility without requiring oversized sensor components.
2Reliability
If the light measurement path is made more robust against particles and foam, then the measurement reliability is improved, but the sensor housing and light path structure become more complex
Solution Approach 1:
The patent applies partial protection by implementing anti-interference measures specifically at critical sections of the light measurement path, particularly between the first and second reflection surfaces where the beam is most vulnerable. Rather than protecting the entire light path uniformly, the design focuses protection on the section where particles and foam bubbles have the greatest impact, achieving adequate measurement reliability without requiring complete redesign of the entire housing structure.
3Reliability
If the light beam cross-sectional area is increased to reduce noise influence, then the measurement stability is improved, but the sensor output signal intensity decreases
Solution Approach 1:
The patent establishes 0.9 mm² as an optimal parameter threshold that balances two opposing requirements: reducing noise susceptibility from particles and foam while maintaining adequate signal intensity. By setting this specific minimum area, the design achieves a compromise point where the light beam is sufficiently wide to minimize the relative impact of scattered particles and foam bubbles, yet not so wide as to excessively dilute the light intensity reaching the detector.
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 design minimizes the impact of particles and foam bubbles on the sensor output, providing a more stable and reliable turbidity measurement with reduced noise and protects the sensor's electronics from water ingress, enhancing its operational reliability.
Implementation Method 1
the light that reaches the light-receiving element, along the light measurement path, from the light-emitting element undergoing total reflection on the first reflection surface and on the second reflection surface
Data Source
AI summary
An optical sensor for use in a washing machine or dishwasher comprises a housing, a light-emitting element, a light-receiving element and a light-conducting structure, which is made from a transparent material, having a light entry point, a first reflection surface, a second reflection surface and a light exit point. A light measurement path runs from the light-emitting element, via the light entry point, the first reflection surface, the second reflection surface and the light exit point, to the light-receiving element wherein the light undergoes total reflection on the first reflection surface and on the second reflection surface and where a light beam that runs from the first reflection surface to the second reflection surface has a cross-sectional area of not less than 0.9 mm2.