Liquid Surface Inspection Device for Bubble Detection

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Solution Overview

Problem

Existing liquid surface condition detectors face challenges in accurately detecting bubbles on the surface of liquids with light-colored or highly diluted samples, and those containing components like grease, due to issues with spectral absorption and computation-intensive methods, leading to increased costs and processing times.

Innovation Solution

A liquid surface condition detector using ring lighting and a camera to capture color information from the liquid surface, employing image processing techniques such as effective zone setting, hue-based pixel counting, and brightness gradient calculation to differentiate between liquid surface reflections and bubble reflections, allowing for accurate bubble detection without relying on expensive illumination or excessive computation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If visible light illumination is used to detect bubbles through mirror surface reflection, then the cost of illumination is low, but the detection accuracy fails for light-colored or highly diluted samples with slight spectral absorption

Engineering Contradiction:
Improvecost of illuminationVSAvoiddetection accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent changes the illumination wavelength from visible light to ultraviolet light (wavelength 300-400nm). This parameter change enables effective bubble detection in light-colored and highly diluted samples because UV light provides sufficient contrast through reflection differences, maintaining detection accuracy without requiring expensive illumination systems.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If multiple image processing techniques (histogram evaluation, FFT evaluation, Hough transformation) are used to detect bubbles, then the detection capability is enhanced, but the computation time and hardware cost increase enormously

Engineering Contradiction:
Improvebubble detection capabilityVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential feature for bubble detection - the mirror surface reflection characteristic - and uses simple pixel counting and ratio calculation to identify bubbles. This extraction approach maintains effective bubble detection capability while eliminating the need for computationally intensive techniques like histogram evaluation, FFT evaluation, and Hough transformation, thereby significantly reducing processing time and hardware requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If the dispense probe is inserted deeper into the liquid to ensure proper suction, then the suction reliability is improved, but the liquid adhesion to the probe wall increases causing contamination

Engineering Contradiction:
Improvesuction reliabilityVSAvoidliquid adhesion and contamination
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent implements feedback control by detecting the liquid surface position using UV illumination and mirror surface reflection characteristics before the dispense probe insertion. The detection unit provides real-time feedback on the liquid surface height, allowing the dispense probe to be inserted to the optimal depth - deep enough to ensure proper suction contact but not so deep as to cause excessive liquid adhesion and contamination. This feedback mechanism maintains suction reliability while minimizing contamination.

Inventive Principle:
Principle #23Feedback

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 the accuracy of bubble detection on various liquid substances at a low cost, reducing contamination risks and processing time, while maintaining reliability and efficiency in automatic analyzers.

Implementation Method 1

illumination is applied from above to the object of inspection and in which an image of the liquid surface is taken through imaging by a color camera. Then, reflection (mirror surface reflection) of the illumination on the liquid surface is extracted

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

reflection (mirror surface reflection) of the illumination on the liquid surface is extracted by utilizing hue information indicating a difference in the ratios of the spectral components of light

Methodology Applied
Scientific EffectMirror surface reflection: Reflection

Data Source

PatentEP3252476B1Liquid surface inspection device, automated analysis device, and processing device
Publication Date: 2024.10.30 HITACHI HIGH TECH CORP
  • EP3252476B1 patent drawingFigure 1
  • EP3252476B1 patent drawingFigure 2
  • EP3252476B1 patent drawingFigure 3

AI summary

Provided are a liquid surface inspection device, an automated analysis device, and a liquid surface inspection method with which instances of contamination can be minimized and the accuracy of the manner in which the surface conditions, such as bubbles or the like, of a liquid substance are detected can be enhanced. The device has: a light illumination unit 102 for illuminating a container 101 holding a liquid substance 1010, as well as the surface of the liquid substance 1010, with light; an image capture unit 103 for acquiring a video image having at least color information and brightness information of light from the container 101 and the liquid substance 1010 which are illuminated by the light illumination unit 102; and a detection unit 104 for using the color information and brightness information in the video image captured by the image capture unit 103 to detect the condition of the liquid surface.