Vehicle compass correction circuit

Claim 2

A vehicle compass correction circuit for correcting for vehicle generated varying interfering magnetic fields comprising: a vehicle accessory providing a varying magnetic field of an intensity sufficient to cause a compass display error; a compass circuit including a magnetic field sensor and display for displaying direction indicating information detected by said magnetic field sensor; and a source of correction signals coupled to said compass circuit to provide correction signal information corresponding to vehicle generated magnetic field disturbances from said vehicle accessory, wherein said compass circuit responds to said correction signals to display a corrected heading corresponding to a heading unaffected by the vehicle accessory generated magnetic field disturbance.

Claim 3

The electrical circuit as defined in claim 1 wherein said source of correction signals comprises a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbances and an output terminal.

Claim 4

The electrical circuit as defined in claim 2 wherein said compass circuit includes a microcontroller having a data input terminal coupled to said output terminal of said detector for receiving correction signals therefrom.

Claim 5

A vehicle compass correction circuit for correcting for vehicle generated varying interfering magnetic fields comprising: a compass circuit including a magnetic field sensor and display for displaying direction indicating information detected by said magnetic field sensor; a source of correction signals coupled to said compass circuit to provide correction signal information corresponding to vehicle generated magnetic field disturbances, said source of correction signals comprises a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbances and an output terminal, wherein said compass circuit includes a microcontroller having a data input terminal coupled to said output terminal of said detector for receiving correction signals therefrom and responds to said correction signals to display a corrected heading corresponding to a heading unaffected by the vehicle generated magnetic field disturbance; and a fan motor for a vehicle HVAC system and an electrical control for varying the current through said fan motor and wherein said input terminal of said detector circuit is coupled to said fan motor.

Claim 6

A vehicle compass correction circuit for correcting for vehicle generated varying interfering magnetic fields comprising: a compass circuit including a magnetic field sensor and display for displaying direction indicating information detected by said magnetic field sensor; a source of correction signals coupled to said compass circuit to provide correction signal information corresponding to vehicle generated magnetic field disturbances, said source of correction signals comprises a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbances and an output terminal, wherein said compass circuit includes a microcontroller having a data input terminal coupled to said output terminal of said detector for receiving correction signals therefrom and responds to said correction signals to display a corrected heading corresponding to a heading unaffected by the vehicle generated magnetic field disturbance; and a fan motor for a vehicle HVAC system and an electrical control for varying the current through said fan motor and wherein said input terminal of said detector circuit is coupled to said fan motor.

Claim 7

The electrical circuit as defined in claim 4 wherein said detector circuit includes a voltage divider coupled from said input terminal to said output terminal for scaling the voltage applied to said input terminal.

Claim 8

The electrical circuit as defined in claim 5 wherein said detector circuit further includes a clamping circuit coupled to said output terminal for limiting the voltage applied to said microcontroller from said detector circuit.

Claim 9

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a vehicle accessory which generates a varying magnetic field which interferes with the compass display accuracy; a magnetic field sensor for providing signals representative of the vehicle heading; a microcontroller coupled to said sensor and to a display for displaying direction indicating information detected by said magnetic field sensor; and a source of correction signals coupled to said microcontroller to provide correction signal information corresponding to vehicle generated magnetic field disturbances caused by said accessory, wherein said microcontroller responds to said correction signals to display the correct heading.

Claim 10

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a vehicle accessory which generates a varying magnetic field which interferes with the compass display accuracy; a magnetic field sensor for providing signals representative of the vehicle heading; a microcontroller coupled to said sensor and to a display for displaying direction indicating information detected by said magnetic field sensor; and a source of correction signals coupled to said microcontroller to provide correction signal information corresponding to vehicle generated magnetic field disturbances caused by said accessory, wherein said microcontroller responds to said correction signals to display the correct heading.

Claim 11

The electrical circuit as defined in claim 7 wherein said source of correction signals comprises a detector circuit having an input terminal for coupling to said vehicle accessory which generates magnetic field disturbances.

Claim 12

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a magnetic field sensor for providing signals representative of the vehicle heading; a microcontroller coupled to said sensor and to a display for displaying direction indicating information detected by said magnetic field sensor; and a source of correction signals coupled to said microcontroller to provide correction signal information corresponding to vehicle generated magnetic field disturbances, wherein said source of correction signals comprises a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbance, and wherein said microcontroller responds to said correction signals to display the correct heading, and wherein the vehicle accessory comprises a fan motor for a vehicle HVAC system and an electrical control for varying the current through said fan motor and wherein said input terminal of said detector circuit is coupled to said fan motor.

Claim 13

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a magnetic field sensor for providing signals representative of the vehicle heading; a microcontroller coupled to said sensor and to a display for displaying direction indicating information detected by said magnetic field sensor; and a source of correction signals coupled to said microcontroller to provide correction signal information corresponding to vehicle generated magnetic field disturbances, wherein said source of correction signals comprises a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbance, and wherein said microcontroller responds to said correction signals to display the correct heading, and wherein the vehicle accessory comprises a fan motor for a vehicle HVAC system and an electrical control for varying the current through said fan motor and wherein said input terminal of said detector circuit is coupled to said fan motor.

Claim 14

The electrical circuit as defined in claim 9 wherein said detector circuit includes an output terminal coupled to said microcontroller and a voltage divider coupled from said input terminal to said output terminal for scaling the voltage applied to said input terminal.

Claim 15

The electrical circuit as defined in claim 10 wherein said detector circuit further includes a clamping circuit coupled to said output terminal for limiting the voltage applied to said microcontroller from said detector circuit.

Claim 16

The electrical circuit as defined in claim 11 wherein said voltage divider includes an integrator circuit.

Claim 17

A vehicle compass including a circuit for correcting for different levels of local magnetic field disturbances caused by operation of electrical accessories in the vehicle, said compass comprising: an electrical accessory which generates a varying magnetic field disturbance; a magnetic field sensor for positioning in the vehicle in proximity to a source of varying magnetic field disturbance caused by said accessory; a source of correction signals identifying the magnetic field disturbance; a display for displaying the detected vehicle heading; and a microcontroller coupled to said sensor and to said source and display and responsive to said correction signals for accurately displaying the vehicle heading for different magnetic field disturbances.

Claim 18

A vehicle compass including a circuit for correcting for different levels of local magnetic field disturbances caused by operation of electrical accessories in the vehicle, said compass comprising: an electrical accessory which generates a varying magnetic field disturbance; a magnetic field sensor for positioning in the vehicle in proximity to a source of varying magnetic field disturbance caused by said accessory; a source of correction signals identifying the magnetic field disturbance; a display for displaying the detected vehicle heading; and a microcontroller coupled to said sensor and to said source and display and responsive to said correction signals for accurately displaying the vehicle heading for different magnetic field disturbances.

Claim 19

A vehicle compass including a circuit for correcting for different levels of local magnetic field disturbances caused by operation of electrical accessories in the vehicle, said compass comprising: a magnetic field sensor for positioning in the vehicle in proximity to a source of varying magnetic field disturbance; a source of correction signals identifying the magnetic field disturbance; a display for displaying the detected vehicle heading; and a microcontroller coupled to said sensor and to said source and display and responsive to said correction signals for accurately displaying the vehicle heading for different magnetic field disturbances, wherein the source of magnetic field disturbance is a multi-speed fan motor and wherein said source of correction signals comprises a detector circuit coupled to said fan motor.

Claim 20

A vehicle compass including a circuit for correcting for different levels of local magnetic field disturbances caused by operation of electrical accessories in the vehicle, said compass comprising: a magnetic field sensor for positioning in the vehicle in proximity to a source of varying magnetic field disturbance; a source of correction signals identifying the magnetic field disturbance; a display for displaying the detected vehicle heading; and a microcontroller coupled to said sensor and to said source and display and responsive to said correction signals for accurately displaying the vehicle heading for different magnetic field disturbances, wherein the source of magnetic field disturbance is a multi-speed fan motor and wherein said source of correction signals comprises a detector circuit coupled to said fan motor.

Claim 21

The compass as defined in claim 14 wherein said detector circuit includes a voltage divider coupled to said fan motor for scaling the voltage applied to said microcontroller.

Claim 22

The compass as defined in claim 15 wherein said detector circuit further includes a clamping circuit for limiting the voltage applied to said microcontroller from said detector circuit.

Claim 23

The compass as defined in claim 16 wherein said voltage divider includes an integrator circuit.

Claim 24

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a vehicle accessory generating a varying magnetic field; a magnetic field sensor for providing signals representative of the vehicle heading; a circuit for providing signals representative of the operation of said accessory which causes dynamic field interference; a speed sensor; a microcontroller coupled to said magnetic field and speed sensors, to said circuit, and to a display for displaying direction indicating information detected by said magnetic field sensor; said microcontroller detecting a predetermined vehicle velocity and detecting changes in the sensed magnetic fields due to changes in the operational state of the vehicle accessory to provide correction signal information corresponding to vehicle generated magnetic field disturbances, wherein said microcontroller responds to said correction signals to provide signals to the display for displaying the corrected heading.

Claim 25

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a vehicle accessory generating a varying magnetic field; a magnetic field sensor for providing signals representative of the vehicle heading; a circuit for providing signals representative of the operation of said accessory which causes dynamic field interference; a speed sensor; a microcontroller coupled to said magnetic field and speed sensors, to said circuit, and to a display for displaying direction indicating information detected by said magnetic field sensor; said microcontroller detecting a predetermined vehicle velocity and detecting changes in the sensed magnetic fields due to changes in the operational state of the vehicle accessory to provide correction signal information corresponding to vehicle generated magnetic field disturbances, wherein said microcontroller responds to said correction signals to provide signals to the display for displaying the corrected heading.

Claim 26

The electrical circuit as defined in claim 18 wherein said predetermined vehicle velocity is zero.

Claim 27

The electrical circuit as defined in claim 19 wherein said source of correction signals comprises a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbances.

Claim 28

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a magnetic field sensor for providing signals representative of the vehicle heading; a circuit for providing signals representative of the operation of an accessory which causes dynamic field interference, said circuit comprising a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbances, wherein the vehicle accessory comprises a fan motor for a vehicle HVAC system and an electrical control for varying the current through said fan motor and wherein said input terminal of said detector circuit is coupled to said fan motor; a speed sensor; and a microcontroller coupled to said magnetic field and speed sensors, to said circuit, and to a display for displaying direction indicating information detected by said magnetic field sensor; said microcontroller detecting zero vehicle velocity and detecting changes in the sensed magnetic fields due to changes in the operational state of said fan motor to provide correction signal information corresponding to vehicle generated magnetic field disturbances, wherein said microcontroller responds to said correction signals to provide signals to the display for displaying the corrected heading.

Claim 29

A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of vehicle accessories, said circuit comprising: a magnetic field sensor for providing signals representative of the vehicle heading; a circuit for providing signals representative of the operation of an accessory which causes dynamic field interference, said circuit comprising a detector circuit having an input terminal for coupling to a vehicle accessory providing internal magnetic field disturbances, wherein the vehicle accessory comprises a fan motor for a vehicle HVAC system and an electrical control for varying the current through said fan motor and wherein said input terminal of said detector circuit is coupled to said fan motor; a speed sensor; and a microcontroller coupled to said magnetic field and speed sensors, to said circuit, and to a display for displaying direction indicating information detected by said magnetic field sensor; said microcontroller detecting zero vehicle velocity and detecting changes in the sensed magnetic fields due to changes in the operational state of said fan motor to provide correction signal information corresponding to vehicle generated magnetic field disturbances, wherein said microcontroller responds to said correction signals to provide signals to the display for displaying the corrected heading.

Claim 30

The electrical circuit as defined in claim 21 wherein said detector circuit includes an output terminal coupled to said microcontroller and a voltage divider coupled from said input terminal to said output terminal for scaling the voltage applied to said input terminal.

Claim 31

The electrical circuit as defined in claim 22 wherein said detector circuit further includes a clamping circuit coupled to said output terminal for limiting the voltage applied to said microcontroller from said detector circuit.