Liquid level induction device, biochemical analyzer and liquid level induction method

Abstract

The invention discloses a liquid level induction device, a biochemical analyzer and a liquid level induction method. The liquid level induction device comprises a sampling probe, a capacitance-to-digital converter and a signal processing device. The capacitance-to-digital converter is used for detecting a capacitance of the sampling probe and converting the capacitance to a digital value to be output, and the signal processing device is used for receiving the digital value, determining whether the sampling probe makes contact with a liquid level or not according to the digital value and outputting a liquid level induction signal to a motor control unit when it is determined that the sampling probe makes contact with the liquid level. Due to the fact that the only one capacitance-to-digital converter is adopted for replacing a converting circuit in the prior art, the problem that a simulation link is long and poor in interference rejection can be effectively solved, the circuit can be simplified, external disturbance can be lowered, and the reliability of the liquid level induction signal can be improved.

Description

technical field [0001] The invention relates to the technical field of measurement, in particular to a liquid level sensing device, a biochemical analyzer and a liquid level sensing method. Background technique [0002] The biochemical analyzer is used for in vitro quantitative detection of various body fluids, such as serum, urine, cerebrospinal cord, etc. Before analyzing body fluids, samples need to be taken. The sampling probe goes down in the sample container driven by the vertical motion motor through the sampling mechanism. When the needle tip touches the liquid level of the sample liquid, the vertical motion motor must decelerate and stop, so as to prevent the sampling probe from hitting the bottom of the sample container and causing damage, or inserting the sample container too deeply to suck the plasma below the serum to cause the needle to be blocked. After absorbing the body fluid, the sampling probe moves upwards and returns driven by the vertical movement motor...

AI Technical Summary

Problems solved by technology

[0006] 1. The analog link is lengthy, and the probe capacitor needs to pass through a capacitor-voltage converter, an analog-to-digital converter, and finally be calculated and processed by a signal processing device, and the capacitor-voltage converter is often composed of an oscillation and frequency division circuit, a phase-locked loop, Composed of discrete components such as amplification and shaping circuits and comparison circuits, the whole process has undergone multiple conversions, which is easily affected by external interference, resulting in decreased sensitivity and even malfunctions;

[0007] 2. The signal processing device often calculates the probe capacitance data by means of threshold value judgment and slope calculation, but abnormal conditions such as probe temperature drift, time drift, and probe hanging liquid will make the probe capacitance value abnormal, resulting in threshold Judgment unit failure, resulting in malfunction

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