Optical Liquid Level Sensing With Meniscus Correction
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Solution Overview
Problem
Existing liquid level sensing technologies inaccurately determine the liquid surface due to the presence of a meniscus, leading to overestimation of the liquid level and potential clogging of dispensing probes.
Innovation Solution
A liquid level sensing apparatus that uses light emitters and photosensors to emit and detect light of different wavelengths, analyzing the change in transmitted light to accurately determine the liquid surface and correct for the meniscus effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light transmission detection is performed without considering meniscus, then detection process is simple, but liquid level detection accuracy deteriorates
Solution Approach 1:
The patent divides the light detection process into multiple segments by performing detection at multiple different positions along the light path. Instead of a single detection point, the system segments the detection into multiple measurements that collectively capture the meniscus effect, enabling accurate liquid level determination while maintaining operational simplicity.
Solution Approach 2:
The patent transitions from one-dimensional detection (single position) to multi-dimensional detection by measuring light transmission at multiple positions. This dimensional expansion allows the system to capture the curvature information of the meniscus and calculate the true liquid level through geometric relationships, resolving the accuracy-complexity contradiction.
2Measurement precision
If multiple light wavelengths are used to detect liquid surface, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent utilizes changes in light transmission parameters (intensity at different wavelengths) as the light passes through the liquid at different positions. By monitoring how transmission characteristics vary with position and wavelength, the system accurately determines liquid surface level and corrects for meniscus effects without requiring complex additional hardware.
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
Accurately determines the liquid level, preventing overestimation and reducing the risk of probe clogging, ensuring precise sample dispensing and minimizing waste.
Implementation Method 1
a light emitter that emits, from a side of a container containing liquid, light of wavelength components with different transmissivities between when light passes through the liquid and when light passes through air
Implementation Method 2
a photosensor that receives transmitted light resulting from light passing through the container after being emitted from the light emitter
Data Source
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AI summary
A liquid level sensing apparatus is provided to determine a position of a liquid level with higher accuracy in contemplation of meniscus. A light emitter, a photosensor and an analysis portion are included. From a side of a container containing liquid, the light emitter emits light of wavelength components with different transmissivities between when the light passes through the liquid and when the light passes through air. The photosensor receives transmitted light resulting from the light passing through the container after being emitted from the light emitter. The analysis portion analyzes transmitted light data on transmitted light at different positions in a vertical direction, the transmitted light data being acquired by the photosensor. The analysis portion detects a top face position of the liquid in the container and also corrects the top face position based on the amount of change in the amount of transmitted light between predetermined positions of the transmitted light data.