Device and method for controlling an optical recognition unit with the help of a capacitive filling level measurement in liquid containers

Patent metadata

Field	Value
Publication number	US-11525727-B2
Application number	US-201917258596-A
Country	US
Kind code	B2
Filing date	Jul 9, 2019
Priority date	Jul 13, 2018
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

A device for controlling an optical recognition unit with the help of a capacitive filling level measurement in liquid containers having a sensor with a measuring electrode, a conductive base plate suitable for arranging at least one liquid container or a carrier unit having at least one receptacle for receiving a liquid container, a sensor electronics unit that is connected to the measuring electrode and the base plate adapted to determine a capacitance between the measuring electrode and base plate, an evaluation unit, and a control unit for controlling the optical recognition unit, is disclosed.

First claim

The invention claimed is:

1. A device for controlling an optical recognition unit with the help of a capacitive filling level measurement in liquid containers ( 1 ), comprising:
the optical recognition unit ( 14 ) with an optical sensor element;
a sensor ( 2 ) having a measurement electrode ( 3 );
a conductive base plate ( 4 ) suitable for arranging at least one liquid container ( 1 ) or a carrier unit ( 5 ) having at least one receptacle ( 6 ) for receiving a liquid container ( 1 );
a sensor electronic unit ( 7 ) which is connected to the measurement electrode ( 3 ) and the conductive base plate ( 4 ) and is adapted to determine a capacitance between the measurement electrode ( 3 ) and the conductive base plate ( 4 );
an evaluation unit (A); and
a control unit ( 15 ) for controlling the optical recognition unit ( 14 ),
wherein the measurement electrode ( 3 ) is arranged substantially perpendicularly to the conductive base plate ( 4 ), and
wherein the evaluation unit (A) is adapted to determine, based on the capacitance, at least one from the following list:

a filling level of the liquid container ( 1 ) or whether the liquid container ( 1 ) is empty and/or exceeds or is below a predetermined filling level;
whether a liquid container ( 1 ) is present in the at least one receptacle ( 6 );
different carrier units ( 5 ), such as carrier units ( 5 ) for differently sized liquid containers ( 1 );
different characteristics on a carrier unit ( 5 ), such as individual receptacles ( 6 ) or partitions between the receptacles ( 6 ),
and wherein the control unit ( 15 ) is connected to the sensor electronics unit ( 7 ) or the evaluation unit (A), and a control signal (sc) can be generated by the sensor electronics unit ( 7 ) or the evaluation unit (A) depending on the capacitance, and the optical recognition unit ( 14 ) is controllable depending on the control signal (sc).

2. The device according to claim 1 , wherein the measurement electrode ( 3 ) is arranged on a front side (V) of a sensor carrier ( 8 ) above a guard electrode ( 9 ).

3. The device according to claim 1 , wherein the measurement electrode ( 3 ) is arranged on a front side (V) of a sensor carrier ( 8 ) between a first and a second guard electrode ( 91 , 92 ).

4. The device according to claim 3 , wherein a third guard electrode ( 93 ) is arranged on a rear side (H) or an intermediate layer (Z) of the sensor carrier ( 8 ), wherein the third guard electrode ( 93 ) covers at least the measurement electrode ( 3 ).

5. The device according to claim 4 , wherein the measurement electrode ( 3 ) and the first and second guard electrode ( 91 , 92 ) are arranged between a first and a second ground electrode ( 101 , 102 ), and wherein the first and second ground electrode ( 101 , 102 ) are arranged between a fourth and a fifth guard electrode ( 94 , 95 ), wherein the first and second ground electrode ( 101 , 102 ) are electrically connected with the conductive base plate ( 4 ).

6. The device according to claim 1 , wherein the measurement electrode ( 3 ), the guard electrodes ( 91 , 92 , 93 , 94 , 95 ) and the ground electrodes ( 101 , 102 ) are designed in the form of strips and are aligned vertically and parallel to a longitudinal axis (a) of the liquid container ( 1 ) during operation of the device.

7. The device according to claim 6 , wherein the measuring electrode ( 3 ) has a width in the range from 80% to 100% of the diameter of the liquid container ( 1 ) and the first and second guard electrode ( 91 , 92 ).

8. The device according to claim 1 , wherein the sensor electronics unit ( 7 ) comprises a signal generator with which a signal (s) for exciting the measuring electrode ( 3 ) can be generated.

9. The device according to claim 8 , wherein the signal (s) for exciting the measuring electrode ( 3 ) is also used for exciting the guard electrodes ( 91 , 92 , 93 , 94 , 95 ), wherein the signal (s′) for exciting the guard electrodes ( 91 , 92 , 93 , 94 , 95 ) is of low impedance.

10. The device according to claim 2 , wherein the sensor carrier ( 8 ) is designed as a printed circuit board.

11. The device according to claim 10 , wherein the sensor electronics unit ( 7 ) is located on the same printed circuit board as the sensor ( 2 ), wherein the printed circuit board has at least two intermediate layers (Z) between the front side (V) and the rear side (H), wherein the measuring electrode ( 3 ) and the first and second guard electrode ( 91 , 92 ) as well as the first and second ground electrode ( 101 , 102 ) as well as the fourth and fifth guard electrode ( 94 , 95 ) are located on the front side (V) of the printed circuit board, the possible third guard electrode ( 93 ) is located on a first intermediate layer behind the front side (V), a ground surface ( 11 ) as shield is located on a second intermediate layer behind the first intermediate layer, wherein the shield is electrically connected with the first and second ground electrode ( 101 , 102 ), and conductor tracks for signal conduction of the sensor electronics unit ( 7 ) are located on the rear side (H) and possibly on one or more further intermediate layers between the rear side (H) and the ground surface ( 11 ).

12. A method for controlling an optical recognition unit with the help of a capacitive filling level measurement in liquid containers ( 1 ), comprising the steps of:
providing a conductive base plate ( 4 ), which is arranged horizontally, and a sensor ( 2 ) having a measurement electrode ( 3 ), which is arranged vertically, and a sensor electronic unit ( 7 ), which is connected to the measurement electrode ( 3 ) and the conductive base plate ( 4 );
arranging a liquid container ( 1 ) or a carrier unit ( 5 ) having at least one receptacle ( 6 ) for accommodating a liquid container ( 1 ) on the conductive base plate ( 4 ) next to the measurement electrode ( 3 );
exciting the measurement electrode ( 3 ) with a signal (s);
determining a measurement signal depending on a capacitance between the measurement electrode ( 3 ) and the conductive base plate ( 4 ); and
determining or recognizing, based on the measurement signal, at least one from the following list:
a filling level of the liquid container ( 1 ) or whether the liquid container ( 1 ) is empty and/or exceeds or is below a predetermined filling level;
whether a liquid container ( 1 ) is present in the at least one receptacle ( 6 );
which type of sample tube ( 1 ) is located in a particular receptacle ( 6 ) of the carrier unit ( 5 );
different characteristics on a carrier unit ( 5 ), such as individual receptacles ( 6 ) or partitions between the receptacles ( 6 );
what kind of carrier unit ( 5 ) it is, such as a carrier unit ( 5 ) adapted to receive sample tubes ( 1 ) of a certain size or maximum filling capacity;

controlling the optical recognition unit ( 14 ) based on the measurement signal.

13. The method according to claim 12 , further comprising the step of:
moving a carrier unit ( 5 ) with a plurality of receptacles ( 6 ) for accommodating sample tubes ( 1 ) in a horizontal direction past the measurement electrode ( 3 ),
wherein the determination of the measurement signal is carried out while moving the carrier unit ( 5 ) past the measurement electrode ( 3 ).

14. The method according to claim 12 , which allows to determine a presence of foam in the liquid container ( 1 ), further comprising the steps:
generating the signal for exciting the measuring electrode ( 3 ) with a first frequency;
generating the signal for exciting the measuring electrode ( 3 ) with a second frequency, wherein the first and second frequency are diffe

Assignees

• Tecan Trading Ag

Inventors

• Ott Philipp
• Frei Luca
• Dieterich Pascal

Classifications

• G01F23/268 Primary

  mounting arrangements of probes · CPC title

• G01F23/266 Primary

  measuring circuits therefor · CPC title

• G01F23/265

  for discrete levels · CPC title