Electric heating – Metal heating – By arc
Patent
1996-04-26
1998-09-15
Mills, Gregory L.
Electric heating
Metal heating
By arc
21912185, 338 32H, 338195, 296101, B23K 2600
Patent
active
058082735
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for adjusting a magneto-resistive sensor.
PRIOR ART
It is known to employ magneto-resistive sensors for the contactless detection of changes in state. For example, this can be an angle measurement of a rotatably seating element. A pseudo-Hall voltage is employed in connection with these magneto-resistive sensors, i.e., while a defined control current is applied to two current contacts of the sensor, the sensor is charged with a magnetic field located in the plane of the sensor by means of a permanent magnet rotating above the sensor, so that a pseudo-Hall voltage, which is proportional to the angle of the magnetization in respect to the flow direction of the control current, is present perpendicularly in respect to the flow direction. The pseudo-Hall voltage is affected by changing the direction of magnetization in respect to the direction of the current inside the magneto-resistive sensor, so that with a steady control current it is possible via the voltage signal to make deductions regarding the position of the magnet creating the magnetic field.
In the meantime it has become known to produce these magneto-resistive sensors from ferromagnetic thin films, in which a magnetically sensitive thin film of, for example, permalloy, is employed, whose output signals, which correspond to the pseudo-Hall voltage, are supplied to an electronic evaluation circuit. In this case the magneto-resistive sensors have a thin film of a binary NiFe alloy (permalloy) and have respectively one current contact on oppositely located long sides. Voltage contacts are provided on the sides of the magneto-resistive sensor extending perpendicularly with the current contacts, on which the already mentioned pseudo-Hall voltage can be picked up. Since in this case this pseudo-Hall voltage is a function of the current intensity of the applied control current and of the angle of magnetization in respect to the direction of the current, an exact symmetrical arrangement of the voltage contacts on the magneto-resistive sensor is important.
However, it is disadvantageous in connection with known production method by means of a mask layout that it is not possible to achieve an exact symmetrical arrangement of the voltage contacts. Caused by this asymmetry, so-called offset voltages occur in the picked-up pseudo-Hall voltage, which cause a distortion in the output signal and therefore a distortion of the measured result, for example the angular position of a rotating element. In this case the offset voltage contains an axial displacement in respect to the zero axis of a sine curve representing the pseudo-Hall voltage. A positive or a negative offset results, depending on the direction in which the asymmetry of the voltage contacts is formed. For compensating this offset it has already been proposed to embody one of the voltage contacts with two poles and to dispose an additional thick film potentiometer between them. It is intended to compensate for the negative or positive offset error by an appropriate adjustment of the potentiometer. However, it is disadvantageous in this connection that, besides the additional introduction of a thick film potentiometer, an additional temperature dependence of the entire magneto-resistive sensor is created, which in turn must be compensated by means of an elaborate temperature compensation.
SUMMARY AND ADVANTAGES OF THE INVENTION
The above mentioned problems of the prior art are generally overcome according to the invention by a process for adjusting a magneto-resistive sensor wherein the magneto-resistive sensor is charged with a homogeneous, definitely oriented magnetic field, a defined contral voltage is applied to its current contracts, and during the measurement of a pseudo-Hall voltage across the voltage contacts, at least one of the voltage contacts is trimmed, for example, with a laser beam.
In contrast to the above mentioned prior art problems the process for the adjustment of a magneto-resistive sensor according to the present invention offers the advantage
REFERENCES:
patent: 3046458 (1962-07-01), Basiago et al.
patent: 3162932 (1964-12-01), Wood et al.
patent: 3789311 (1974-01-01), Masuda
patent: 3947934 (1976-04-01), Olson
patent: 4259563 (1981-03-01), Madeley
patent: 4698522 (1987-10-01), Larsen et al.
"Sensors", vol. 5, Magnetic Sensors, Ed.: Boll und Overshott, VCH Verlag Weinheim (DE), 1989, pp. 367-369.
Petersen, Dipl.-Phys. August; "Drehzahlmessung mit magnetoresistiven Sensormodulen"; Elektronik, vol. 2, 1991, pp. 78-81.
Mech, Klaus et al; "Magnetfeldjager"; Elrad, vol. 10, 1993; pp. 48-51.
Taschenbuch Elektrotechnik, vol. 3, Edition 1, Carl Hanser Verlag Munchen, Vienna 1978, pp. 94-96.
Dukart Anton
Galster Rudolf
Gerlach Guenter
Jost Franz
Marx Klaus
Mills Gregory L.
Robert & Bosch GmbH
LandOfFree
Process for tuning a magneto-resistive sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for tuning a magneto-resistive sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for tuning a magneto-resistive sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-90799