Method and device for distinguishing between a foam and/or liquid contacting
AssigneeTecan Trading AG
InventorsPhilipp Ott, Lars Kamm, Markus Schöni, Remo Keller, Paul Zbinden
Life of this patent
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Abstract
A method and device for distinguishing between a contacting of foam (2) or of liquid (1) in a liquid container (5) of a device (100) by employing a capacitively operating measuring device (M) having a sensor (3) which can be moved up and down in the liquid container (5), in which at least one output signal (sout(t)) is processed by the measuring device (M).
Claims15
Method for distinguishing between a contacting of foam (2) or of liquid (1) in a liquid container (5) of a device (100) by means of a capacitively operating measuring device (M) having a sensor (3) which can be moved up and down in the liquid container (5), wherein at least one output signal (sout(t)) is processed by the measuring device (M), the method comprising the following steps:
- a. executing an up or down movement (B) of the sensor (3) in the liquid container (5);
- b. applying an input signal (sin(t)) having a first frequency (f1) to the sensor (3);
- c. applying the input signal (sin(t)) having a second frequency (f2) to the sensor (3), where the second frequency (f2) and the first frequency (f1) are different;
- d. within the framework of a first process (P1)—evaluating the output signal (sout(t)) in order to detect a first jump (ΔX1) of the output signal (sout(t));
- e. within the framework of a second process (P2)—evaluating the output signal (sout(t)) in order to detect a second jump (ΔX2) of the output signal (sout(t)),
- f. comparing the first jump (ΔX1) with the second jump (ΔX2);
- g. outputting an identifier (Ks, Kf) which signals a contacting of the sensor (3) with foam (2) in the liquid container (5) if the comparison exceeds a specification, and which signals a contacting of the sensor (3) with liquid (1) in the liquid container (5) if the comparison does not exceed the specification.
Apparatus which is equipped with a capacitively operating measuring device (M) for distinguishing between a contacting of foam (2) or of liquid (1) in a liquid container (5), wherein the apparatus comprises a movable sensor (3), an input signal generator (E) and an evaluation circuit (A), wherein the input signal generator (E) is connectable in terms of circuitry to the sensor (3) or to the liquid container (5) and wherein the evaluation circuit (A) is connectable in terms of circuitry to the sensor (3) or to the liquid container (5) so that the output signal (sout(t)) is processable by the evaluation circuit (A), characterized in that the input signal generator (E)
- is configured to be able to determine the capacitance of the sensor (3) at a first frequency (f1) and at a second frequency (f2), where the second frequency (f2) and the first frequency (f1) are different,
- and in that the evaluation circuit (A)
- is configured to evaluate the output signal (sout(t)) in order to detect a first jump (ΔX1) of the output signal (sout(t)) and a second jump (ΔX2) of the output signal (sout(t));
- is configured to compare the first jump (ΔX1) with the second jump (ΔX2);
- is configured to output an identifier (Ks Kf) which signals a contacting of the sensor (3) with foam (2) in the liquid container (5) if the comparison exceeds a specification, and which signals a contacting of the sensor (3) with liquid (1) in the liquid container (5) if the comparison does not exceed the specification.
Dependencies are inferred from the claim text.