Geartooth sensor with means for selecting a threshold magnitude as a function of the average and minimum values of a signal of magnetic field strength
First Claim
1. A magnetic sensor, comprising:
- a permanent magnet;
a magnetically sensitive component disposed proximate said magnet;
first means, connected to said magnetically sensitive component, for providing a first output signal which is representative of the presence of a ferromagnetic member within a detection zone of said sensor;
second means, connected to said first providing means, for providing a second output signal which is representative of an average value of said first output signal over a first preselected period of time;
third means, connected to said first providing means, for providing a third output signal which is representative of a minimum value of said first output signal over a second period of time;
fourth means, connected to said second and third providing means, for providing a fourth output signal which is a function of the difference between said second and third output signals; and
fifth means, connected to said first and fourth providing means, for providing a fifth output signal which is representative of the difference between said first and fourth output signals.
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Accused Products
Abstract
A geartooth sensor is provided with a circuit which determined a threshold magnitude as a function of the minimum value of a first output signal from a magnetically sensitive component and an average output signal from a magnetic sensitive component. Circuitry is provided to determine the average signal. The minimum signal is then subtracted from the average signal and the resulting signal is doubled before being scaled by a predetermined fraction and then compared to the original output signal from the magnetically sensitive component. This circuit therefore determines a threshold signal as a function of both the minimum signal value and the average signal value and, in addition, enables the resulting signal to be scaled to a predetermined percentage of this difference for the purpose of selecting a threshold value that is most particularly suitable for a given application.
81 Citations
18 Claims
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1. A magnetic sensor, comprising:
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a permanent magnet; a magnetically sensitive component disposed proximate said magnet; first means, connected to said magnetically sensitive component, for providing a first output signal which is representative of the presence of a ferromagnetic member within a detection zone of said sensor; second means, connected to said first providing means, for providing a second output signal which is representative of an average value of said first output signal over a first preselected period of time; third means, connected to said first providing means, for providing a third output signal which is representative of a minimum value of said first output signal over a second period of time; fourth means, connected to said second and third providing means, for providing a fourth output signal which is a function of the difference between said second and third output signals; and fifth means, connected to said first and fourth providing means, for providing a fifth output signal which is representative of the difference between said first and fourth output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A magnetic sensor, comprising:
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a permanent magnet; a magnetically sensitive component disposed proximate said magnet; first means, connected to said magnetically sensitive component, for providing a first output signal which is representative of the presence of a ferromagnetic member within a detection zone of said sensor; second means, connected to said first providing means, for providing a second output signal which is representative of an average value of said first output signal over a first preselected period of time; third means, connected to said first providing means, for providing a third output signal which is representative of a minimum value of said first output signal over a second period of time; fourth means, connected to said second and third providing means, for providing a fourth output signal which is a function of the difference between said second and third output signals; and fifth means, connected to said first and fourth providing means, for providing a fifth output signal which is representative of the difference between said first and fourth output signals, said second providing means comprising means for amplifying said average value of said second output signal. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A magnetic sensor, comprising:
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a permanent magnet; a magnetically sensitive component disposed proximate said magnet; first means, connected to said magnetically sensitive component, for providing a first output signal which is representative of the presence of a ferromagnetic member within a detection zone of said sensor; second means, connected to said first providing means, for providing a second output signal which is representative of an average value of said first output signal over a first preselected period of time; third means, connected to said first providing means, for providing a third output signal which is representative of a minimum value of said first output signal over a second period of time; fourth means, connected to said second and third providing means, for providing a fourth output signal which is a function of the difference between said second and third output signals; and fifth means, connected to said first and fourth providing means, for providing a fifth output signal which is representative of the difference between said first and fourth output signals, said fourth output signal being generally equal to two times the difference between the average value of said first output signal and said third output signal. - View Dependent Claims (15, 16, 17, 18)
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Specification