Complementary linear magnetic position sensor
First Claim
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1. A complementary linear magnetic sensor for sensing the position of a structure along an axis of travel, said sensor comprising:
- first and second magnetic sensors mounted in a spaced relationship for providing respective first and second sensor outputs signals indicative of the strength of a magnetic field, said first and second magnetic sensors having respective first and second sensor active areas, and said sensors being connected in a complementary fashion so that said first and second signals are oppositely signed;
an elongated magnetic bar secured to said structure, said magnet bar comprising a single magnet extending along the extent of a range of travel over which said sensor is to measure position, said bar mounted at an angle with respect to said axis of travel and arranged to move with said structure, said magnet bar disposed for movement between said first and second sensor active areas, so that as said magnet bar traverses a range of movement, its position relative to said sensor active areas will shift, thereby transforming said magnet bar movement into a magnetic flux change to which said sensor active areas are responsive, and wherein over at least a portion of said range of movement, said sensor output signals change as a substantially linear function of the position of the magnet bar within the range of movement; and
processor circuitry responsive to said first and second output signals for determining the position of said structure along said axis.
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Abstract
Linear Hall effect magnetic sensor elements (52, 54) are used in a complementary fashion in a position sensor (50). The oppositely signed signal voltages of the sensor elements are amplified and fed into a microprocessor circuit (66). Deviations from the linearity can be compensated by lookup tables. Temperature changes can be measured and included into the compensation process.
47 Citations
17 Claims
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1. A complementary linear magnetic sensor for sensing the position of a structure along an axis of travel, said sensor comprising:
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first and second magnetic sensors mounted in a spaced relationship for providing respective first and second sensor outputs signals indicative of the strength of a magnetic field, said first and second magnetic sensors having respective first and second sensor active areas, and said sensors being connected in a complementary fashion so that said first and second signals are oppositely signed; an elongated magnetic bar secured to said structure, said magnet bar comprising a single magnet extending along the extent of a range of travel over which said sensor is to measure position, said bar mounted at an angle with respect to said axis of travel and arranged to move with said structure, said magnet bar disposed for movement between said first and second sensor active areas, so that as said magnet bar traverses a range of movement, its position relative to said sensor active areas will shift, thereby transforming said magnet bar movement into a magnetic flux change to which said sensor active areas are responsive, and wherein over at least a portion of said range of movement, said sensor output signals change as a substantially linear function of the position of the magnet bar within the range of movement; and processor circuitry responsive to said first and second output signals for determining the position of said structure along said axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A complementary linear magnetic position sensor for sensing the position of a structure along an axis of travel, said sensor comprising:
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first and second magnetic sensors mounted in a spaced relationship for providing respective first and second sensor output signals indicative of the strength of a magnetic field, said first and second sensors having respective first and sensor active areas; first and second magnet bars secured to said structure, said magnet bars being substantially the same and each comprising a single magnet extending along the extent of a range of travel over which said sensor is to measure position, said bars mounted at opposed angles with respect to said axis of travel and arranged to move with said structure, said magnet bars disposed for movement adjacent corresponding ones of said first and second sensor active areas so that said first and second signals are oppositely signed, and so that as said magnet bars traverse a range of movement, their respective positions relative to the first and second sensor active areas will shift, thereby transforming said magnet bar movement into magnetic flux changes to which said respective first and second sensor active areas are responsive, and wherein over at least a portion of said range of movement, said sensor output signals change as a substantially linear function of the position of the magnet bars within the range of movement; and processor circuitry responsive to said first and second outputs signals for determining a measured position of said structure. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification