Electricity: measuring and testing – Magnetic – Displacement
Patent
1995-07-20
1997-07-22
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Displacement
324252, 338 32R, G01B 730, G01R 3309, G01D 516
Patent
active
056507216
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates generally to devices for detecting the angular position of an object, and more particularly to a device for detecting the angular position of an object relative to a preset zero position with a magnetoresistive (MR) sensor which has a constant reference axis plus contacts for supplying an electric current and is arranged in a magnetic field, where one magnetic field component (H or H.sub.g) of the magnetic field and the reference axis of the MR sensor can be rotated by an angle of rotation (.THETA. or .phi.) with respect to each other in a plane of rotation, where this angle of rotation has an unambiguous correlation with the angular position to be determined, and the electrical resistance of the MR sensor is an unambiguous function of this angle of rotation (.THETA. or .phi.). Such a device is disclosed, for example, in the Philips Technical Information Brochure TI 901228 "Properties and Applications of KMZ 10 Magnetic Field Sensors."
In one embodiment of this known device for measuring the angular position, a magnetoresistive barber-pole sensor is set up in the field of a rotationally mounted magnet.
Magnetoresistive sensors are composed in general of a thin layer of a magnetoresistive material which is magnetized in the plane of the layer. When the magnetization of the layer is rotated with respect to the direction of a measurement current flowing in the layer by a magnetic field which is to be measured, there is a change in resistance that may amount to several percent of the normal isotropic resistance and can be detected as a measurement signal. This effect is called anisotropic magnetoresistance or the anisotropic magnetoresistive effect (AMR). The customary magnetoresistive materials are ferromagnetic transition metals such as Nickel (Ni), iron (Fe), or Cobalt (Co) and alloys made with these metals. At least one rectangular strip that is made of the ferromagnetic NiFe alloy known commercially as Permalloy and is magnetized in its longitudinal direction is provided with the magnetoresistive barber-pole sensor used in the known angle measurement device. Several thin metal strips are arranged side by side on the Permalloy strip at an angle of 45.degree. to the longitudinal direction of the Permalloy strip. If voltage is now applied to the Permalloy strip in its longitudinal direction, an electric current is generated between the metal strips, where the direction of this current is essentially at an angle of .+-.45.degree. or .+-.135.degree., depending on the polarity of the voltage, to the magnetization of the Permalloy strip. An external magnetic field that is to be measured and has a component at right angles to the magnetization then rotates the magnetization of the Permalloy strip relative to the direction of the current which remains constant. This rotation causes a change in resistance that has an approximately linear dependence on the magnetic field. The characteristic curve of the resistance of such a barber-pole sensor is unambiguous and at least approximately linear for an angle range of approximately 90.degree., which may be selected between about +45.degree. to -45.degree. or about -45.degree. and +45.degree. for the angle between the magnetization and the measurement current.
The magnetic field of the rotatable magnet is thus provided both as a measurement field and as a supporting field to stabilize the sensor characteristic. Rotation of the magnet through an angle to be measured creates a change in the resistance signal of the barber-pole sensor. The measurement range of this angle-measuring device is limited to a maximum of .+-.90.degree. because the sensor has an unambiguous characteristic curve only in this angular range. Larger angles up to .+-.135.degree. can be achieved by using the supporting field of an additional magnet. Angles of up to almost .+-.180 degrees are feasible by using two sensors set up at right angles to one another and analyzing their measurement signals in the individual angle quadrants. Possible applica
REFERENCES:
patent: 4949039 (1990-08-01), Grunberg
patent: 5134533 (1992-07-01), Friedrich et al.
patent: 5159513 (1992-10-01), Dieny et al.
patent: 5287238 (1994-02-01), Baumgart et al.
patent: 5313186 (1994-05-01), Schuhl et al.
patent: 5462795 (1995-10-01), Shinjo et al.
Patent Abstracts of Japan, vol. 6, No. 95, 3 Jun. 1982 & JP-A-57027081.
IEEE Transactions on Magnetics, vol. MAG-22, No. 5, Sep. 1986, New York, US, pp. 394-396, Nelson et al.: Shear-Sensitive Magnetoresistive Robotic Tactile Sensor.
Physical Review Letters, vol. 61, No. 21, 21 Nov. 1988, pp. 2472-2475, M.N. Baibich et al.: Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices.
Journal of Magnetism and Magnetic Materials, North Holland, vol. 113, 1992, pp. 79-82, T. Okuyama et al.: vol. 113, 1992, pp. 79-82, T. Okuyama et al.: Magneto-transport phenomena of multilayered films with two magnetic components.
Technische Informationen (Technical Information) TI 901228 of the firm of Philips GmbH, Hamburg, DE: Eigenschaften und Anwendungen der Magnetfeldsensoren KMZ 10 (Characteristics and usages of Magnetic Field Sensors KMZ 10).
Berg Hugo Van Den
Schelter Wolfgang
Siemens Aktiengesellschaft
Strecker Gerard R.
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