Back to results
US 6,724,187 B2Granted
Methods for eliminating error sources of magnetic sensors used for the measurement of coating thickness
AssigneeAutomation Hans Nix GmbH
InventorNorbert Nix
Life of this patent
Estimating the term…
Abstract
A method which compensates errors resulting from offset voltages and external magnetic fields when a magnetic sensor is used to measure coating thickness. The method also allows compensation of a temperature dependent change for output voltages of the magnetic sensor.
Claims8
A method for determining the thickness of a coating on a ferro-magnetic substrate using a device having a magnetic sensor element and a coil, the method comprising the steps:
- placing the device on the coated ferro-magnetic substrate;
- measuring a first output voltage of the magnetic sensor element generated by an external disturbing magnetic field incident on the magnetic sensor element;
- and
- generating a magnetic field by applying a direct current to the coil and measuring a second output voltage of the magnetic sensor elements;
- wherein
- the first voltage measured in the first step is subtracted from the second voltage measured in the second steps;
- to yield a difference, and
- the difference is used to determine the thickness of the coating on the ferro-magnetic substrate.
5 more elements
A method for determining the thickness of a coating on a ferro-magnetic substrate using a device having a magnetic sensor element and a coil, the method comprising the steps:
- placing the device on the coated ferro-magnetic substrate;
- generating a first output voltage U1 in the magnetic sensor element by a magnetic field B1, which is generated by a first current l1 in the coil, the first output voltage being dependent on the distance of the magnetic sensor element from the ferro-magnetic substrates, and on external disturbing magnetic field incident on the magnetic sensor element, wherein
- a control unit determines the first output voltage of the magnetic sensor element generated in the first generating step;
- a second current I2 passing through the coil and a resulting magnetic field B2 generates a second output voltage U2;
- the control unit determines the second output voltage of the magnetic sensor element generated in the second generating step;
- and
- an evaluation unit determines the coating thickness from a difference in the first and second output voltages.
4 more elements
Dependencies are inferred from the claim text.