Optical Sensor for Detergent Category Detection in Washing Machines
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Solution Overview
Problem
Domestic laundry-washing appliances lack the ability to accurately detect the chemical category of detergents used, leading to potential damage from mismatched detergent types and wash programs, as existing sensors only differentiate between powdered and liquid detergents or detect turbidity without identifying chemical properties.
Innovation Solution
An optical sensor with a measuring device that determines the spectral transmission signature of the washing liquid, categorizing detergents based on chemical properties by comparing measured values to reference signatures, and controlling the wash operation accordingly, distinguishing between heavy-duty, color, and mild detergents through specific wavelength measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing sensors (turbidity sensors) are used to detect detergent type, then the sensor can differentiate between powdered and liquid detergents or detect turbidity, but it cannot identify the chemical properties or category of the detergent
Solution Approach 1:
The patent applies parameter changes by measuring light transmission at multiple different wavelengths (spectral transmission signature) rather than a single wavelength. Different detergent categories (heavy-duty, color, mild) have distinct spectral transmission characteristics at various wavelengths, allowing the sensor to identify chemical properties by analyzing how the detergent solution transmits light across the spectrum. This transforms the measurement approach from simple turbidity detection to multi-parameter spectral analysis.
Solution Approach 2:
The patent uses light as an intermediary substance to detect detergent chemical properties. By passing light through the detergent solution and analyzing the spectral transmission signature, the system indirectly identifies detergent categories without direct chemical interaction. This intermediary approach enables chemical property detection while maintaining sensor system simplicity.
2Reliability
If detergent category is not accurately detected, then the appliance cannot control wash programs appropriately, but implementing accurate detection increases device complexity
Solution Approach 1:
The patent measures light transmission at multiple wavelengths to capture the spectral transmission signature of the detergent solution. Each detergent category (heavy-duty with optical brighteners, color detergent, mild detergent) exhibits characteristic absorption and transmission patterns at different wavelengths. By analyzing these spectral parameters, the system reliably identifies detergent categories and matches appropriate wash programs, ensuring textile protection without requiring complex chemical analysis devices.
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
Enables accurate detergent categorization, preventing damage to textiles by ensuring appropriate wash programs are selected and optimizing detergent dosing, thereby enhancing cleaning effectiveness and safety.
Implementation Method 1
optical measuring device which serves to obtain measured values which are representative of a spectral transmission signature of a washing liquid
Data Source
AI summary
A domestic laundry-washing appliance including an optical measuring device for obtaining measured values which are representative of a spectral transmission signature of a washing liquid used during operation of the laundry-washing appliance for cleaning textiles, and a control device which is adapted to categorise a cleaning agent contained in the washing liquid in respect of its chemical properties on the basis of the spectral transmission signature obtained, and to control the operation of the laundry-washing appliance in dependence on the categorisation result. The categorisation result can indicate, for example, a distinction between a heavy-duty detergent containing bleach and another bleach-free detergent.