A liquid level detecting circuit is pattern-printed on a board. The liquid level detecting circuit has a pair of discharge elements and an electrostatic capacitance change detecting circuit. One of the discharge elements is grounded, and the other of the discharge elements is connected to a pipetting probe and the electrostatic capacitance change detecting circuit. When an extraneous noise signal such as a noise signal caused by static electricity charged on the surface of a container is input through the pipetting probe while the pipetting probe is being moved toward the container containing a liquid the liquid surface of which is to be detected, the extraneous noise signal is discharged to the ground through the pair of discharge elements to suppress the transmission of the noise signal to be transmitted to the electrostatic capacitance change detecting circuit. An inductance placed between the other discharge element and the electrostatic capacitance change detecting circuit promotes the discharge of the noise signal.
An automatic analysis apparatus with a liquid level detection function includes a pipetting device for pipetting a liquid sample from a sample cup to a reaction container by using a pipetting probe that serves as a first capacitor electrode. A sample cup holding means serves as a second capacitor electrode having a ground potential. The conductor material is arranged along a direction in which the pipetting probe moves down for pipetting and is separate from the pipetting device. The conductor material has the same ground potential as that of the sample cup holding means and also serves as a second electrode whereby at any one time either of the sample cup holding means and the conductive material serves as a second capacitor electrode in combination with the first capacitor electrode. An a electrical detector is provided for detecting a change of electrode static capacitance between the pipetting probe and the sample cup holding means and between the pipetting probe and the conductive material as of level detection of the liquid sample. Measurement means are also provided for measuring an ingredient of the reaction container.
The invention concerns a liquid transfer device for an analysis apparatus with a liquid transfer cannula (5) and a capacitive liquid level detector to detect the immersion of the liquid transfer cannula (5) in an analysis liquid contained in a vessel. To reliably check if the liquid transfer cannula (5) is submerged in the analysis liquid or immersed for example in foam it is proposed additionally that resistance is measured by a measurement section (16) in the liquid transfer cannula (5).
The present disclosure generally relates to a capacitance sensing apparatus equipped with self-calibrating capacity and method of use thereof. The disclosure contemplates the determination using a secondary means of precise fluid levels according to five possible embodiments, and the use of the determined fluid level to recalibrate the capacitance sensing apparatus along its continuous analog level, namely, a variation of the thickness of the insulation of a capacitance sensing apparatus, the variation of the surface geometry of the capacitance sensing apparatus, the use of a dual-probe sensor including a probe with a varied surface geometry, the use of an electromagnetic sensor adjoining the capacitance sensor, and the variation of the electromechanical sensor to serve as a capacitance sensing apparatus. The disclosure also contemplates methods for using the sensing apparatus previously disclosed to measure a fluid level using a self-calibrating capacitance sensing apparatus. Finally, the present disclosure contemplates the use of an improved mathematical method associated with a variability measurement, such as an exponential smoothing method, to determining locally discrete changes in the variability measurement of the capacitance in order to determine a fixed fluid level.
The present disclosure generally relates to a capacitance sensing apparatus equipped with self-calibrating capacity and method of use thereof. The disclosure contemplates the determination using a secondary means of precise fluid levels according to five possible embodiments, and the use of the determined fluid level to recalibrate the capacitance sensing apparatus along its continuous analog level, namely, a variation of the thickness of the insulation of a capacitance sensing apparatus, the variation of the surface geometry of the capacitance sensing apparatus, the use of a dual-probe sensor including a probe with a varied surface geometry, the use of an electromagnetic sensor adjoining the capacitance sensor, and the variation of the electromechanical sensor to serve as a capacitance sensing apparatus. The disclosure also contemplates methods for using the sensing apparatus previously disclosed to measure a fluid level using a self-calibrating capacitance sensing apparatus. Finally, the present disclosure contemplates the use of an improved mathematical method associated with a variability measurement, such as an exponential smoothing method, to determining locally discrete changes in the variability measurement of the capacitance in order to determine a fixed fluid level.
