Capacitive locating appliance having opposing electrodes

Patent metadata

Field	Value
Publication number	US-9470646-B2
Application number	US-201314388987-A
Country	US
Kind code	B2
Filing date	Feb 14, 2013
Priority date	Mar 29, 2012
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

A locating appliance for a capacitive detection of an object encloses in a medium. The locating appliance comprises a measurement electrode such that a first alternating current flows from the measurement electrode into the medium. The locating appliance further comprises a reception electrode where the measurement electrode forms a measurement capacitance with the reception electrode, where the measurement capacitance is based at least in part on the object. The locating appliance further comprises a reference electrode such that the reference electrode forms a reference capacitance with the reception electrode, where the reference capacitance is not based on the object. The locating appliance further comprises a first opposing electrode that is configured to introduce a first alternating current in the medium. The absolute value of the second alternating current corresponds to an absolute value of the first alternating current and is in antiphase with the second alternating current.

First claim

The invention claimed is:

1. A locating appliance for a capacitive detection of an object enclosed in a medium, the locating appliance comprising:
a measurement electrode configured to induce a first alternating current in the medium;
a first opposing electrode, the first opposing electrode being configured to induce a second alternating current in the medium that is in antiphase with the first alternating current, the second alternating current having an amplitude that corresponds to an amplitude of the first alternating current;
a reception electrode configured to form a measurement capacitance with the measurement electrode, the measurement capacitance being influenced by a presence of the object, the reception electrode being further configured to form a reference capacitance that is unaffected by the presence of the object.

2. The locating appliance as claimed in claim 1 , further comprising:
a reference electrode, the reference electrode being configured to induce a third alternating current in the medium,
wherein the reference capacitance is formed from the reference electrode and the reception electrode.

3. The locating appliance as claimed in claim 2 :
a first voltage source connected to the measurement electrode, the first voltage source being configured to drive the measurement electrode to induce the first alternating current in the medium;
a second voltage source connected to the first opposing electrode, the second voltage source being in antiphase with the first voltage source and configured to drive the first opposing electrode to induce the second alternating current in the medium; and
a third voltage source connected to the reference electrode, the third voltage source being in antiphase with the first voltage source and configured to drive the reference electrode to induce the third alternating current in the medium.

4. The locating appliance as claimed in claim 3 further comprising:
a first device configured to control second voltage source such that the amplitude of the second alternating current corresponds to the amplitude of the first alternating current.

5. The locating appliance as claimed in claim 3 further comprising:
a second opposing electrode, the second opposing electrode configured to induce a fourth alternating current in the medium that is in antiphase with the third alternating current, the fourth alternating current having an amplitude that corresponds to an amplitude of the third alternating current; and
a fourth voltage source connected to the second opposing electrode, the fourth voltage source being in antiphase with the third voltage source and configured to drive the second opposing electrode to induce the fourth alternating current in the medium.

6. The locating appliance as claimed in claim 5 further comprising:
a second device configured to control the fourth voltage source such that the amplitude of the fourth alternating current corresponds to the amplitude of the third alternating current.

7. The locating appliance as claimed in claim 5 further comprising:
a shielding electrode connected to a constant potential, the shielding electrode at least partially covering the measurement electrode, the reference electrode, the reception electrode, the first opposing electrode, and the second opposing electrode, the shielding electrode being positioned on a side of the locating appliance that is averted from the object,
wherein the measurement electrode, the reference electrode, the reception electrode, the first opposing electrode, and the second opposing electrode are arranged in a common plane.

8. The locating appliance as claimed in claim 3 further comprising:
a control device configured to control at least one of the first voltage source and the third voltage source to match a first influence of electrical fields from the measurement electrode on the reception electrode to a second influence of electric fields from the reference electrode on the reception electrode.

9. The locating appliance as claimed in claim 2 further comprising:
a plurality of first electrodes and a plurality of second electrodes, the measurement electrode, the reference electrode, and the reception electrode being surrounded by an alternating arrangement of the first electrodes and the second electrodes, the first electrodes of the alternating arrangement being electrically connected to the measurement electrode and the second electrodes of the alternating arrangement being electrically connected to the reference electrode.

10. The locating appliance as claimed in claim 1 , wherein the first opposing electrode forms a capacitance with the medium and is further configured to induce the second alternating current in the medium capacitively.

11. The locating appliance as claimed in claim 1 , wherein the first opposing electrode is resistively coupled to the medium and is further configured to induce the second alternating current in the medium resistively.

12. The locating appliance as claimed in claim 1 further comprising:
a bridge measurement circuit configured to detect the object based at least in part on a ratio between the measurement capacitance and the reference capacitance.

13. A locating appliance for a capacitive detection of an object enclosed in a medium, the locating appliance comprising:
a measurement electrode, the measurement electrode being driven by a first voltage source configured to induce a first alternating current in the medium;
a first opposing electrode, the first opposing electrode being driven by a second voltage source, the second voltage source being in antiphase with the first voltage source and configured to induce a second alternating current in the medium, the second alternating current having an amplitude that corresponds to an amplitude of the first alternating current;
a reference electrode, the reference electrode being driven by a third voltage source, the third voltage source being in antiphase with the first voltage source and configured to induce a third alternating current in the medium; and
a reception electrode configured to form a measurement capacitance with the measurement electrode and form a reference capacitance with the reference electrode, the measurement capacitance being influenced by a presence of the object, the reference capacitance being unaffected by the presence of the object.

Assignees

• Bosch Gmbh Robert

Inventors

• Zibold Tobias
• Albrecht Andrej

Classifications

• G01V3/088 Primary

  operating with electric fields (G01V3/082 takes precedence) · CPC title

• G01N27/22 Primary

  by investigating capacitance · CPC title