Automatic Analyzer Liquid Level Detection Using Electrostatic Capacity
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Solution Overview
Problem
Existing automatic analyzers face challenges in accurately detecting the liquid level in containers due to issues like contact with the container wall, bubbles, and static electricity, leading to erroneous readings and delays in clinical tests.
Innovation Solution
An automatic analyzer with a dispensing unit, oscillation circuit, detection unit, and multiple determination processors that analyze time-series oscillating frequency data to differentiate between proper liquid level detection and errors, determining the reason for gaps and providing accurate notifications for corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrostatic capacity system is used to detect liquid level, then detection speed is improved, but detection accuracy deteriorates due to erroneous detection from container wall contact, bubbles, or static electricity
Solution Approach 1:
The detection process is divided into multiple independent determination processors, each analyzing specific features of the electrostatic capacity waveform (such as slope, curvature, time characteristics) to separately evaluate different aspects of liquid level detection accuracy, reducing false positives from bubbles, static electricity, or container wall contact
Solution Approach 2:
The system uses the extracted features from electrostatic capacity waveform as feedback to continuously adjust and refine the determination of liquid level detection accuracy, comparing actual waveform characteristics against expected patterns to identify and correct erroneous detections in real-time
2Measurement precision
If multiple determination processors are added to improve detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Multiple determination processors are designed to analyze different features of the same electrostatic capacity waveform signal, allowing each processor to serve a specific analytical function while collectively achieving comprehensive detection accuracy improvement without requiring separate physical sensing systems
Solution Approach 2:
A feature extraction unit serves as an intermediary between the electrostatic capacity sensor and multiple determination processors, preprocessing the raw signal into standardized features that all processors can utilize, reducing overall system complexity by centralizing signal processing functions
3Ease of operation
If conventional electrostatic capacity detection is used, then ease of operation is maintained, but loss of information occurs due to inability to identify detection errors
Solution Approach 1:
The system automatically identifies and classifies detection errors (such as bubbles, static electricity interference, or container wall contact) through multiple determination processors, providing self-diagnostic information without requiring additional manual intervention or complex operational procedures from the user
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 system enables high-accuracy detection of liquid level errors, reducing the risk of incorrect sample concentration readings and minimizing test delays by identifying the cause of errors and providing recommended coping procedures.
Implementation Method 1
the electrostatic capacity between the suction unit (tip portion) of a dispensing probe and a surrounding portion (for example, the ground of the apparatus housing) is monitored, and a change in the electrostatic capacity is detected
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to an aspect of the present invention, there is provided an automatic analyzer that detects a liquid level by using an electrostatic capacity system. Feature values are extracted from time-series oscillating frequency data of an alternating current signal that is output by an oscillation circuit (4) in a period from a time point at which a dispensing probe (1a) starts moving downward till a time point at which a certain period of time has elapsed. On the basis of the feature values from the time-series oscillating frequency data, it is determined whether or not the liquid level in a container (2) has been detected properly, by using different methods. Whether a gap is present between the tip portion of the dispensing probe (1a) and the liquid level in the container (2) and a reason for the gap are determined from a combination of multiple determination results obtained by using the methods.