Flux-gate sensor electrical drive method and circuit
First Claim
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1. A drive circuit for providing signals to a primary winding of a flux-gate-type magnetic sensor used in a vehicle compass system comprising:
- a microprocessor for providing first and second frequency electrical drive signals having periodic waveforms wherein said second frequency signals are harmonically related to said first frequency signals;
an electrical circuit coupled to said microprocessor for receiving said first frequency signals and including means for coupling an output of said electrical circuit to the primary winding of a flux-gate sensor, said electrical circuit providing an output signal which when applied to the primary winding of a flux-gate sensor causes saturation of the core of the flux-gate sensor at about midway of at least one half cycle of each period of said first frequency signals; and
detector means coupled to said microprocessor and to said sensor and responsive to said second frequency signals applied thereto from said microprocessor for detecting second frequency components of signals from said sensor which represents direction heading information for the compass.
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Abstract
An electrical drive dircuit for a flux-gate magnetic sensor used in a digital compass for a vehicle provides signals for application to the primary of a flux-gate sensor to assure the core is saturated at a predetermined time during each cycle of the drive signal.
82 Citations
25 Claims
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1. A drive circuit for providing signals to a primary winding of a flux-gate-type magnetic sensor used in a vehicle compass system comprising:
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a microprocessor for providing first and second frequency electrical drive signals having periodic waveforms wherein said second frequency signals are harmonically related to said first frequency signals; an electrical circuit coupled to said microprocessor for receiving said first frequency signals and including means for coupling an output of said electrical circuit to the primary winding of a flux-gate sensor, said electrical circuit providing an output signal which when applied to the primary winding of a flux-gate sensor causes saturation of the core of the flux-gate sensor at about midway of at least one half cycle of each period of said first frequency signals; and detector means coupled to said microprocessor and to said sensor and responsive to said second frequency signals applied thereto from said microprocessor for detecting second frequency components of signals from said sensor which represents direction heading information for the compass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electrical drive circuit for a flux-gate sensor used in a vehicle compass system comprising:
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a flux-gate sensor having a primary winding; a current shunting resistor coupled in parallel with said primary winding; a power supply having outputs providing a first output voltage, a second output voltage having a value less than said first voltage and a ground reference voltage, wherein one terminal of said primary winding is coupled to said voltage source to receive said second voltage therefrom; a source of periodic electrical drive signals; and controlled switch means having a control input terminal coupled to said source and three switch terminals, with a first terminal coupled to said ground reference, a second terminal coupled to said power supply to receive said first output voltage, and a third terminal coupled to a terminal of said primary winding opposite said one terminal thereof, said switch means responsive to said drive signals to provide current flow in alternate directions through said primary winding. - View Dependent Claims (12, 13, 14, 15)
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16. An electrical compass system for a vehicle comprising:
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a flux-gate sensor having a primary winding and a pair of orthogonally oriented secondary windings wound around a core; a source of first and second frequency signals with said second frequency signals having a harmonic relationship to said first signals and phase shifted with respect thereto; a drive circuit having an input coupled to said source and having an output coupled to said primary winding for providing periodic signals at said first frequency which saturate said core at about the mid-point of each half cycle of each period wherein said drive circuit comprises a current shunting resistor coupled in parallel with said primary winding, a power supply having outputs providing a first output voltage, a second output voltage having a value less than said first voltage and a ground reference voltage, wherein one terminal of said primary winding is coupled to said voltage source to receive said second voltage therefrom; and
controlled switch means having a control input terminal coupled to said source and three switch terminals, with a first terminal coupled to said ground reference, a second terminal coupled to said power supply to receive said first output voltage, and a third terminal coupled to a terminal of said primary winding opposite said one terminal thereof, said switch means responsive to said drive signals to provide current flow in alternate directions through said winding; andcircuit means coupled to said secondary windings and said source for processing signals from said secondary windings in predetermined timed relationship thereto to provide output signals representative of the direction of orientation of the flux-gate sensor with respect to the earth'"'"'s magnetic field; and display means coupled to said circuit means for displaying the heading of the vehicle in response to signals from said circuit means. - View Dependent Claims (17, 18, 19, 20, 21)
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22. An electrical compass system for a vehicle comprising:
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a flux-gate sensor having a primary winding and a pair of secondary windings; a microprocessor for providing first and second frequency signals with said second frequency signals having a predetermined frequency relationship to said first signals; a drive circuit having an input coupled to said microprocessor and having an output coupled to said primary winding for providing periodic drive signals to said primary winding at said first frequency; detector means coupled to said secondary windings and to said microprocessor and responsive to second frequency signals from said microprocessor for processing signals from said secondary windings in predetermined timed relationship to said first frequency signals to provide signals to at least one input terminal of said microprocessor such that said microprocessor provides output signals representative of the direction of orientation of the flux-gate sensor with respect to the earth'"'"'s magnetic field; and display means coupled to said microprocessor for displaying the heading of the vehicle in response to signals from said microprocessor. - View Dependent Claims (23, 24, 25)
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Specification