SI24352A - The capacitive level detector medium - Google Patents

Abstract

The object of the invention is a capacitive media level detector, e.g. liquids at a coffee or similar apparatus. The capacitive detector allows by measuring 5 changes in the capacitance of the touch sensor caused by the change in quantity and consequently the height of the medium (water) in the reservoir, measuring the level of the medium without any intervention into the container itself or contact of the measuring sensor with a controlled medium. A 10 sensor (2) is attached to the wall of the container (1) (using glue or otherwise), which represents one electrode of the imaginary condenser. The second electrode represents the medium (water - dielectric) in the grounded housing of the container for the medium (water). Depending on the height of the medium in the container, the capacitance of the imaginary capacitor is also changing. The change in the capacitance of the imaginary capacitor is thus proportional to the change in the amount of the content of the medium in the container 1 and can be converted to the signal for displaying the quantity or the corresponding signal circuit (3). level media in the container. The higher the level of the media in the container, the greater the capacitance of the labeled capacitor.

Description

The subject of the invention is a capacitive media level detector, e.g. liquids - water in a coffee or similar apparatus. Capacitive detector enables measuring the change of capacitance of the touch sensor, which is caused by the change in the amount and consequently the height of the medium (liquid - water) in the container, to measure the level of the medium without interfering with the container itself. contact of the measuring sensor with a controlled medium. The capacitive level detector of the medium according to the invention, due to its construction design, also enables measurement in apparatus in which the media container is removable, or. portable. Such measurement enables the detection of a full, empty container, continuous measurement of the level of the medium in the container, as well as the detection of the presence of the container itself on the apparatus. The invention belongs to class H03K 17/96 of the international patent classification.

A technical problem that the present invention successfully solves is the construction and implementation of a capacitive media level detector in a coffee machine that allows indirect measurement of the media level without contacting the detector with the contents in the coffee machine container.

Solving the technical problem of detecting the level of the medium (liquid20 water) in the container can be carried out with a continuous meter, in which two electrodes are immersed in the medium in the container. Such a meter operates on the principle that the dielectricity of the medium and the air is different, so their mutual capacitance depends on the level of the medium in the container.

Similarly, the discrete principle of measurement works, where several different long electrodes are immersed in the medium in the vessel and the capacitance varies with the number of concluded electrodes, which represent individual discrete levels of levels.

As the conductivity of the media and thus their dielectricity varies with temperature, this must be taken into account in the measurement result or proper calibration performed. The accuracy of the measurement is also affected by the corrosion of the electrodes and the accumulation of dirt on them and on the inner wall of the container.

There is also an embodiment in which a cylindrical metal tube with insulation is inserted into the conductive medium where the electrode is inserted. The role of the dielectric is assumed by the medium and the air above it. Such a change in capacitance is caused by a level-dependent relationship between the two dielectrics. While the capacitance is also influenced by the level dependent change of the capacitor surface.

The discrete measurement principle works in the same way, but here we change the capacitance with respect to the number of concluded electrodes, which represent the individual discrete values of the levels.

From the patent documentation known solutions of devices for measuring the water level of the coffee machine. Patent Document AU2005100608A4

2o successfully resolves the detection of water level, unlike it, our solution according to the invention solves the non-invasive principle of measurement (the measuring method has no direct contact with the medium), as well as the fact that the measuring result represents a continuous value for us. Patent Document VV001 / 60221A1 and

US2010 / 0326282A1 successfully solves the use of a capacitive measuring method in a coffee machine, our solution according to the invention represents a simpler integration of the measuring electrode, making its position irrelevant. The metal strip (printed matter) can be mounted on the inside wall of the appliance and a clear signal about the water level in the container is obtained through the measuring and communication controller.

Patent Document DE102010034376A1 protects the idea of an invasive measuring method by capacitive measurement on a metal tank on a parallel line. Our idea of the invention is much simpler and less expensive and allows measuring the level without special adjustments of the container itself. In most cases, the operation of our method is enabled by plug & play.

The invention will be explained in more detail on the basis of an embodiment and figures, of which:

is Fig. 1 is a schematic view of a solution of a capacitive media level detector for a coffee or similar apparatus;

figure 2 block diagram of the measurement system.

The capacitive media level detector according to the invention uses the principle of capacitive contact sensor described in the basic embodiment in patent document WO 2013/004603. The capacitive contact sensor operates on the principle of detecting capacitance between the transmitting, receiving and sensing electrodes, which are interconnected capacitively. When touched, · · the mutual capacitance changes so that the capacitance of the touch is added to it. In this way, the change in capacitance can be used as a control signal for switching.

Figure 1 shows a schematic solution for implementing the operation of the capacitive sensor described above. A sensor 2 is attached to the wall of container 1 (by adhesive or otherwise), representing one electrode of an imaginary capacitor. Sensor 2 can be a metal strip or double sided. The second electrode is a medium (water-dielectric) in the earthed housing of the medium (water) container. Depending on the height of the medium in the io container, the capacitance of the imaginary capacitor also varies. The change in the capacitance of an imaginary capacitor is thus proportional to the change in the amount of media content in the container 1 and can be transformed into a signal for displaying the quantity or the corresponding signal circuit 3. the media level in the container. The higher the media level in the container, the greater the capacitance of the imaginary capacitor.

Figure 2 shows a block diagram of a measuring system that can be used with the capacitive sensor described above. The sensor 2, represented by a metal strip or double-sided printed matter, is attached to the container 1 in which the media level is to be measured. Measurement circuit 3 contains a capacitive voltage divider 4, a circuit 5 for digital data processing and a decoder 6. A capacitive voltage divider 4 measures the change in capacitance and adjusts it to us with useful information by digital signal processing. When passing the signal through the decoder 6, we also take into account the change in the average measured value, thus eliminating the effect of aging, i.e. the application of scale on the walls of container 1 and other changes in the physical quantities of the measured medium and the display on the output display 7.

Claims (5)

PATENT APPLICATIONS 1. Capacitive media level detector, characterized in that 5 that a sensor is attached to the wall of the container (1) 2), which represents one electrode of an imaginary capacitor, while the other electrode represents a medium (water-dielectric) in a grounded housing of a medium (water) container. io 2. Capacitive media level detector according to claim 1, characterized in that the sensor (2) of the container (1) is via a measuring circuit ( 3) connected to the display (7) to display the results. Capacitive media level detector according to claim 2, characterized in that the measuring circuit (3) comprises a capacitive voltage divider (4) for measuring the change in capacitance, a circuit (5) for digital signal processing and a decoder (6) to account for the change average 20 measured values and other changes in the physical quantities of the measured medium. Capacitive media level detector according to claims 1 to 3, characterized in that the capacitive detector measurement process comprises the following steps: installing the sensor (2) on the container (1), 5 measuring capacitance change with capacitive voltage divider (4), digital signal processing in the circuit (5), considering changes in average measured value and other changes in physical quantities of the measured medium by means of an io decoder (6) displaying the results on the output display (7).