Capacitive sensor for measuring the level of a substance in a tank

A capacitive sensor for measuring a level of a substance in a tank, comprising:

• a motherboard with a plurality of layers including one or more areas of components comprising measuring electrodes, an electronic signal conditioning circuit, and tracks for connecting the measuring electrodes to the electronic signal conditioning circuit, a first layer of the plurality of layers comprising an area including the measuring electrodes, wherein the measuring electrodes are linearly distributed and the tracks for connecting the measuring electrodes to the electronic signal conditioning circuit:
• each comprise the same shape and length, and;
• are surrounded by a guard plate and at least one shielding plate, each of the guard plate and the at least one shielding plate made of a conductive material, the guard plate being configured to be subjected to a guard voltage substantially equal to a measuring voltage of the measuring electrodes to prevent coupling between the tracks that may influence a capacitance measured by each of the measuring electrodes, and the at least one shielding plate being connected to ground for the electromagnetic shielding of the tracks, and
• wherein the plurality of layers further comprise a second layer comprising a shielding plate of the at least one shielding plate and a third layer comprising the guard plate as well as the tracks for connecting the measuring electrodes to the electronic signal conditioning circuit, wherein each track is inserted into a corresponding elongated window made on the guard plate, wherein the first layer and the second layer are outer layers of the motherboard, and wherein the third layer is arranged between the first layer and the second layer.

A capacitive sensor for measuring a level of a substance in a tank, comprising:

• a motherboard with a plurality of layers including one or more areas of components comprising measuring electrodes, an electronic signal conditioning circuit, and tracks for connecting the measuring electrodes to the electronic signal conditioning circuit,
• a first layer of the plurality of layers comprising an area including the measuring electrodes, wherein the measuring electrodes are linearly distributed and the tracks for connecting the measuring electrodes to the electronic signal conditioning circuit:
• each comprise the same shape and length, and;
• are surrounded by a guard plate and at least one shielding plate, each of the guard plate and the at least one shielding plate made of a conductive material, the guard plate being configured to be subjected to a guard voltage substantially equal to a measuring voltage of the measuring electrodes to prevent coupling between the tracks that may influence a capacitance measured by each of the measuring electrodes, and the at least one shielding plate being connected to ground for the electromagnetic shielding of the tracks, and
• wherein the electronic signal conditioning circuit is configured to measure the capacitance of the each of the measuring electrodes at the measuring voltage by connecting all the measuring electrodes to one and the same voltage.