Sensing system for measuring a parameter
First Claim
1. A sensing system for measuring a parameter, comprising:
- a hall element;
means for establishing, in said hall element, a first magnetic flux having a magnitude which is a function of the parameter to be measured,said hall element thereby producing a hall voltage having a polarity and an amplitude determined by the first magnetic flux;
a polarity detector, coupled to said hall element, for developing an output voltage of a polarity determined by that of the hall voltage;
an integrator for integrating the output voltage of said polarity detector;
cancelling means for establishing, in said hall element and in response to the integrator output voltage, a second magnetic flux of equal magnitude but of opposite direction relative to the first magnetic flux, the net flux in said hall element, and the resulting hall voltage, thereby tending to become zero;
and means, included in said cancelling means, for producing a control voltage which is proportional to and represents the measured parameter.
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Accused Products
Abstract
A parameter, such as the current flowing through a conductor, is measured by initially passing an energizing magnetic flux through a hall element to produce a hall voltage proportional to the sensed parameter. To eliminate temperature, aging and non-linear effects normally associated with a hall element, the amplitude of the hall voltage is effectively ignored and only its polarity is detected and employed to control the operation of an integrator to develop a cancelling current to establish an equal, but opposite direction, cancelling flux in the hall element. With a zero net flux, the integrator will hold the cancelling current at the level required to balance out and cancel the initial energizing flux. Since the cancelling current needed to null the energizing flux will be proportional to that flux, the current may be used to produce a control voltage to represent the measured parameter.
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Citations
13 Claims
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1. A sensing system for measuring a parameter, comprising:
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a hall element; means for establishing, in said hall element, a first magnetic flux having a magnitude which is a function of the parameter to be measured, said hall element thereby producing a hall voltage having a polarity and an amplitude determined by the first magnetic flux; a polarity detector, coupled to said hall element, for developing an output voltage of a polarity determined by that of the hall voltage; an integrator for integrating the output voltage of said polarity detector; cancelling means for establishing, in said hall element and in response to the integrator output voltage, a second magnetic flux of equal magnitude but of opposite direction relative to the first magnetic flux, the net flux in said hall element, and the resulting hall voltage, thereby tending to become zero; and means, included in said cancelling means, for producing a control voltage which is proportional to and represents the measured parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification