Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
  • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
  • G01D5/142—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
  • G01D5/145—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields

Definitions

• the invention relates to an angle sensor comprising at least one flat magnetoresistive sensor element, each of which has:
• an angle sensor which comprises a combination of a first sensor element assigned to the first supply voltage or to the first supply current and a second sensor element assigned to the second supply voltage or the second supply current.
• the direction of the drop in the first supply voltage or of the flow of the first supply current is rotated or offset by a defined angle, for example by about 45 degrees, with respect to the direction of the drop in the second supply voltage or of the flow of the second supply current.
• Sensor elements of the described type which are designed not with meandering conductor strips but rather with closed, flat conductor structures which comprise e.g. rectangular or circular layers of the material Permalloy applied to a silicon substrate, are characterized by a very low ohmic resistance. Typical resistance values lie in the region of a few Ohms. It has been found that these resistance values thus come to lie in a value range which lies close to the value range of the resistance values of the leads to the flat conductor structures for supplying the supply voltages or supply currents, that is to say close to the value range of the lead resistances of the bond connections to the actual sensor structure.
• the resistance values of the leads to the flat conductor structures thus have an appreciable influence on the supply voltages acting on the flat conductor structures or on the flow of the supply currents.
• the voltage losses which occur along these lead resistances during operation considerably falsify the measurement result and thus have a significant influence on the quality of the measurement signal that is produced, said signal being intended to be an indication of the angle of the field lines of a magnetic field acting on the angle sensor relative to the angle sensor.
• the object of the invention is to avoid the above-described defects in an angle sensor of the type mentioned above.
• this object is achieved in that at least the first supply terminal or one of the first supply terminals and at least the second supply terminal or one of the second supply terminals of at least one of the sensor elements is coupled to a power source for supplying an impressed supply voltage to the at least one sensor element.
• the angle sensor according to the invention is designed with two flat magnetoresistive sensor elements, each of which has a first and a second supply terminal and also two tapping electrodes, and the magnetoresistive sensor elements are arranged in a series connection with one another and with their common power source via their supply terminals.
• This ensures that the two sensor elements are fed the same supply current, so that the ratio of the amplitudes of the measurement signals output by the sensor elements no longer depends on variations in the current intensity of this supply current.
• the influence of the lead resistances on the tapping electrodes which also exists in principle, is reduced to a negligible level by virtue of a measurement circuit with high-ohmic inputs.
• the magnetoresistive sensor elements are advantageously of at least substantially the same geometric shape and size.
• the magnetoresistive sensor elements, with respect to the plane of their flat dimension are furthermore arranged at least substantially parallel and in this plane with respect to one another and in a manner rotated by a predefined angle with respect to one another.
• the predefined angle of the rotated arrangement of the magnetoresistive sensor elements with respect to one another corresponds to at least almost 45°.
• the sensor element is or the sensor elements are advantageously designed as sensors which are based on the principle of the anisotropic magnetoresistive effect, so-called A[nisotropic]M[agneto]R[esistive] sensors.
• Fig. 1 shows an example of a schematic circuit diagram comprising two magnetoresistive sensor elements which according to the invention are connected to one another and to their common power source via their supply terminals.
• Fig. 2 shows an example of a schematic circuit diagram of an angle sensor in the configuration according to the invention, with an evaluation device for angle measurement.
• Fig. 1 schematically shows a first flat magnetoresistive sensor element 1 and a second flat magnetoresistive sensor element 2 of an angle sensor.
• Their magnetoresistive, current-conducting layers which are preferably made of Permalloy, have a circular contour.
• the magnetoresistive sensor elements 1, 2 are preferably designed as AMR sensor elements.
• the first sensor element 1 is provided with a first 10 and a second supply terminal 11. Via the supply terminals 10, 11, the first sensor element can be acted on by a supply voltage or a supply current.
• a drop in the supply voltage in a direction along the flat dimension of the first sensor element 1, said direction being shown schematically and being denoted by the reference UVl is produced in the first sensor element 1; this direction UVl is also the direction of the flow of the supply current in the first sensor element 1.
• the second sensor element 2 is provided with a first 20 and a second supply terminal 21 via which it can be acted on by a supply voltage and a supply current.
• the first sensor element 1 is furthermore provided with a first 12 and a second tapping electrode 13, via which a first measurement voltage UMl is tapped off from the first sensor element 1 during operation.
• the second sensor element 2 is provided with a first 22 and a second tapping electrode 23, via which a second measurement voltage UM2 is tapped off from the second sensor element 2 during operation.
• the measurement voltages UMl, UM2 are shown schematically as arrows in Fig. 1.
• the sensor elements 1 and 2 are connected in a series connection with one another and with a common power source 30, said series connection being arranged in the illustrated example between a voltage source terminal 31 and ground 32.
• a first terminal of the power source 30 is connected to the voltage source terminal 31 and a second terminal of the power source 30 is connected to the first supply terminal 10 of the first magnetoresistive sensor element 1.
• the second supply terminal 11 of the first magnetoresistive sensor element 1 is connected to the first supply terminal 20 of the second magnetoresistive sensor element 2 via a connecting line 33, and the second supply terminal 21 of the second magnetoresistive sensor element 2 is connected to ground 32.
• a common current which is denoted IS in Fig. 1 is passed through both sensor elements 1 and 2 during operation.
• Fig. 2 schematically shows an example of embodiment of the use of an angle sensor with two sensor elements 1, 2 for angle measurement. Elements of the drawing which correspond to Fig. 1 are again provided with the same references.
• a first and a second measurement voltage input 41 and 42 of an evaluation device 40 are connected to the first and second tapping electrode 12 and 13 of the first magnetoresistive sensor element 1 in order to supply the first measurement voltage UMl to the evaluation device 40.
• a third and a fourth measurement voltage input 43 and 44 of the evaluation device 40 are connected to the first and second tapping electrode 22 and 23 of the second magnetoresistive sensor element 2 in order to supply the second measurement voltage UM2 to the evaluation device 40.
• the measurement voltage inputs 41, 42, 43, 44 are designed to be high-ohmic, so that the sensor elements are not appreciably loaded at the tapping electrodes and thus no signal falsifications occur.
• the measurement voltages UMl, UM2 are processed in the manner described in said application to form an output signal which is output during operation at an output 45, said output signal forming an output signal of an angle measurement system comprising the angle sensors 1, 2 and the evaluation device 40.
• This output signal is an information item regarding the angle, with respect to the angle sensor, of the component of the field lines of a magnetic field acting on the angle sensor which runs in the plane of the flat dimension of the sensor elements 1, 2. This component of the field lines is shown schematically in Fig. 2 by an arrow bearing the reference H.
• H component of the field lines of a magnetic field acting on the angle sensor which runs in the plane of the flat dimension of the sensor elements IS common current through the sensor elements UMl first measurement voltage, tapped off via the first and second tapping electrode of the first sensor element UM2 second measurement voltage, tapped off via the first and second tapping electrode of the second sensor element UVl direction of the drop in the supply voltage or of the flow of the supply current along the flat dimension of the first sensor element UV2 direction of the drop in the supply voltage or of the flow of the supply current along the flat dimension of the second sensor element

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Magnetic Variables (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

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• 2006
  • 2006-01-13 JP JP2007550912A patent/JP2008527370A/ja not_active Withdrawn
  • 2006-01-13 EP EP06701784A patent/EP1842032A1/en not_active Withdrawn
  • 2006-01-13 CN CNA2006800025977A patent/CN101151509A/zh active Pending
  • 2006-01-13 WO PCT/IB2006/050123 patent/WO2006077508A1/en active Application Filing

Non-Patent Citations (1)

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