Detecting probe liquid level detector and method

Abstract

The invention discloses a probe liquid level detection method and device, comprising the following steps: receiving a capacitance value signal output by a liquid suction probe; outputting a voltage signal corresponding to the capacitance value according to the change of the capacitance value; judging the current voltage signal Whether the voltage value of the voltage value is greater than the low threshold value, if so, calculate the slope of the adjacent voltage signal; judge whether the slope is greater than the slope threshold value, if yes, add 1 to the first liquid level mark counter, if not, add 1 to the first liquid level mark counter Subtracting 1; judging whether the value of the first liquid level flag counter is greater than or equal to the first set value, and if so, outputting a contact liquid level indication signal. The invention not only improves the detection sensitivity, but also enhances the working reliability.

Description

【Technical field】 [0001] The invention relates to a liquid level sensing device, in particular to a device and a method for detecting the liquid level of a sample in the sampling process of an automatic biochemical analyzer. 【Background technique】 [0002] The biochemical analyzer needs to take samples first when analyzing body fluids. The liquid suction probe is driven by the motor to go down in the test tube. When it touches the liquid surface, the motor must stop in order to prevent the needle tube from touching the bottom of the test tube and absorbing unnecessary body fluids. After absorbing the body fluid, the needle tube goes up and returns under the drive of the motor. Therefore, liquid level detection must be carried out during biochemical analysis. When the needle tube touches the liquid level, it is necessary to output a contact liquid level indication signal to the motor control unit, so as to control the motor to stop. Existing liquid level detection technologi...

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Problems solved by technology

[0006] However, this liquid level detection scheme is purely implemented by analog circuits. As long as the voltage value of the current voltage signal is greater than the set threshold, the contact liquid level indication signal will be output immediately. This scheme has poor anti-interference ability and is prone to interference and false detection. As a result, errors occur in the control of the stepping motor. In order to increase the reliability of the detection, that is, the anti-interference ability, it can only be realized by increasing the comparison threshold of the comparison circuit. However, simply increasing the comparison threshold will reduce the detection sensitivity on the one hand. On the one hand, it requires a large amount of reagents and samples

With the development of automatic biochemical analyzer technology and the requirements of environmental protection, laboratories are using less and less reagent volume and sample volume, which puts forward higher requirements for detection sensitivity. However, the existing liquid level detection scheme is especially Not suitable for liquid level detection of small amounts of liquids

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