Reference Circuit for Liquid Level Detection Self-Testing
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Solution Overview
Problem
Existing laboratory devices face challenges in precisely detecting liquid levels due to small capacitance changes and interference from stray capacitances and crosstalk, requiring complex and time-consuming testing and calibration procedures.
Innovation Solution
A self-test method using a reference circuit that simulates liquid level detection, allowing for automatic testing without manual intervention, and capable of recognizing crosstalk and incorrect connections by altering the effective capacitance through a series circuit of capacitors and switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated circuits are used for liquid level detection with fine adaptation, then measurement precision is improved, but device complexity and testing requirements increase
Solution Approach 1:
The patent uses a reference circuit that copies the structure and electrical characteristics of the actual liquid level detection circuit. This reference circuit includes a capacitor that can be switched between different states to simulate the capacitance changes detected during liquid level measurement. By testing the reference circuit instead of the actual detection circuit, the patent simplifies testing while maintaining measurement precision requirements.
Solution Approach 2:
The reference circuit acts as an intermediary between the test device and the actual liquid level detection circuit. It provides a simplified interface for testing by simulating the electrical behavior of the detection circuit without requiring the complex physical setup of actual liquid containers and sensors. This intermediary allows standard test equipment to verify circuit functionality without direct access to the complex detection system.
2Reliability
If manual testing and calibration procedures are used, then testing thoroughness is improved, but productivity and testing time decrease
Solution Approach 1:
The reference circuit is designed to be self-testing through automatic switching between different capacitor states. The circuit can autonomously simulate various liquid level conditions by switching the reference capacitor, eliminating the need for manual intervention in the testing process. This self-service capability maintains thorough testing while significantly improving productivity.
Solution Approach 2:
The testing process uses periodic switching of the reference capacitor between different states to simulate various liquid level conditions. This periodic action allows the test device to systematically verify circuit response under different conditions in an automated sequence, improving both thoroughness and speed compared to manual testing.
3Adaptability or versatility
If high spatial compaction of components is implemented, then device integration is improved, but mutual influencing of adjacent measuring channels increases
Solution Approach 1:
The patent extracts the testing function from the actual measuring channels by using a separate reference circuit. This reference circuit is electrically isolated from the adjacent measuring channels, preventing crosstalk during testing. The reference circuit can be switched in and out of the testing path without interfering with or being interfered by neighboring channels, thus maintaining high device integration while eliminating harmful electromagnetic coupling.
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 simple and reliable testing of liquid level detection circuits, reducing testing time and effort while identifying potential issues such as crosstalk and faulty connections, ensuring precise and efficient operation of laboratory devices.
Implementation Method 1
The effective capacitance, which results depending on the laboratory device from the stray capacitances, electrical couplings by the feeler or the pipette tip 3, the conductivity of the liquid 1, and the crosstalk between adjacent measuring channels
Data Source
AI summary
The invention relates to devices for liquid level detection (LLD). It relates to a laboratory device having an electronic circuit for detecting a liquid level in a liquid container, a feeler, which can be advanced, and which is connected to an input side of the electronic circuit, and having a movement device, which allows the feeler to be advanced in the direction of the liquid in the liquid container. Upon the immersion of the feeler in the liquid, a capacitance change is caused in the electronic circuit, which triggers a signal in the circuit. The laboratory device comprises a reference circuit, which is connected to the input side of the circuit, and which specifies an effective capacitance on the input side of the circuit. A sequence controller is used, which causes the triggering of a test by the application of a control signal to the reference circuit, the control signal causing an increase of the effective capacitance through a switching procedure. The processing of the corresponding capacitance change is monitored by the sequence controller, for example.