Adaptive Turbidity Sensor Control for Dishwasher Wash Liquid
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Solution Overview
Problem
Existing turbidity sensors have limited accuracy and operating ranges due to the characteristics of typical transmittance-turbidity curves and the limitations of light-sensitive elements, leading to inaccurate measurements at high and low turbidity values.
Innovation Solution
A turbidity sensor with a variable light source and controller that adjusts the radiant intensity based on measured light intensity, using threshold values to extend the operating range and improve accuracy by selecting from predetermined intensity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed intensity light source is used in the turbidity sensor, then the device structure is simple, but the measurement accuracy deteriorates at high and low turbidity values due to saturation and noise limitations of the light-sensitive element
Solution Approach 1:
The patent applies the dynamics principle by making the light source intensity variable rather than fixed. The controller dynamically adjusts the radiant intensity of the light source based on the measured light intensity from the light-sensitive element, allowing the system to adapt to different turbidity conditions. This resolves the contradiction by enabling accurate measurements across a wide turbidity range while managing complexity through automated control based on feedback signals.
Solution Approach 2:
The patent applies parameter changes by varying the radiant intensity parameter of the light source. The controller selects from multiple predetermined intensity levels to optimize the light intensity for different turbidity conditions. This prevents saturation at low turbidity and ensures sufficient signal above noise threshold at high turbidity, thereby improving measurement accuracy without requiring a completely complex system design.
2Measurement precision
If the radiant intensity of the light source is increased to improve signal strength, then the measurement sensitivity improves, but the light-sensitive element saturates at low turbidity values reducing measurement accuracy
Solution Approach 1:
The patent applies feedback by using the output signal from the light-sensitive element to control the radiant intensity of the light source. The controller continuously monitors the measured light intensity and adjusts the light source intensity accordingly. This feedback mechanism ensures that the light intensity is optimized for each measurement condition, preventing saturation while maintaining sufficient signal strength, thereby improving both sensitivity and reliability.
Solution Approach 2:
The system dynamically adjusts the light source intensity based on real-time measurement conditions. By making the light intensity variable and controllable, the system can adapt to prevent saturation at low turbidity while maintaining sensitivity. This dynamic adjustment resolves the contradiction between improving signal strength and avoiding saturation, enhancing both measurement precision and reliability.
3Reliability
If the radiant intensity of the light source is decreased to avoid saturation, then the light-sensitive element operates within its linear range, but the signal becomes drowned in noise at high turbidity values
Solution Approach 1:
The feedback mechanism allows the controller to monitor the measured light intensity and adjust the light source radiant intensity accordingly. When turbidity is high and the signal is weak, the controller increases the light source intensity to maintain signal strength above the noise threshold. This resolves the contradiction by ensuring reliable measurements at low turbidity while maintaining detection capability at high turbidity through adaptive intensity control.
Solution Approach 2:
The patent changes the radiant intensity parameter of the light source based on measurement conditions. By selecting from multiple predetermined intensity levels, the system can increase intensity when needed to overcome noise at high turbidity while maintaining appropriate intensity levels for reliable operation at low turbidity. This parameter adjustment resolves the contradiction between avoiding saturation and maintaining signal detection capability.
4Adaptability or versatility
If a single light intensity level is used to simplify the control system, then the device complexity is reduced, but the operating range of the sensor is limited
Solution Approach 1:
The patent applies parameter changes by implementing multiple predetermined radiant intensity levels for the light source. This allows the sensor to adapt to a wider range of turbidity conditions by selecting the appropriate intensity level. The controller automatically manages these multiple levels based on feedback from the light-sensitive element, extending the operating range while keeping the control system manageable through automated selection rather than manual complexity.
Solution Approach 2:
The light source is designed to perform multiple functions by operating at different intensity levels. A single light source structure achieves what would otherwise require multiple light sources, providing both low-intensity operation for low turbidity and high-intensity operation for high turbidity. This multi-functionality extends the measurement range while avoiding the complexity of multiple separate light source systems.
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 sensor achieves improved accuracy and a wider operating range by dynamically adjusting the light intensity, reducing error sensitivity and extending the measurement range beyond the limitations of traditional sensors.
Implementation Method 1
a light source for emitting light, the light having a radiant intensity which is variable... light emitted from the light source propagates through a fluid on its way to the light sensitive element
Implementation Method 2
a light-sensitive element for receiving light emitted from the light source... the light-sensitive element is configured to measure the radiant intensity of light received at the light-sensitive element
Implementation Method 3
the controller is configured to adjust, by selecting one intensity level out of a plurality of predetermined intensity levels, the radiant intensity of the light emitted by the light source in dependence of the measured radiant intensity of light received at the light-sensitive element
Data Source
AI summary
A turbidity sensor for use in a machine for washing articles, e.g., a washing machine (400). The turbidity sensor comprises a light source (210) for emitting light. The emitted light has a radiant intensity which is variable. The sensor further comprises a light-sensitive element (220) for receiving light emitted from the light source (210). The light source (211) and the light-sensitive element (220) are positioned relative to each other so that, when the light source (210) is in operation, light emitted from the light source (210) can propagate through a washing liquid contained in the washing machine (400) on its way to the light sensitive element (220). The light-sensitive element (220) is configured to measure the radiant intensity of light received at the light-sensitive element (221). Furthermore, the sensor comprises a controller (230) which is communicatively coupled to the light source (210) and the light-sensitive element (220). The controller (230) is configured to adjust the radiant intensity of the light emitted by the light source (210) in dependence of the measured radiant intensity of light received at the light-sensitive element (220).