Vehicle compass circuit

• US 5,664,335 A
• Filed: 06/06/1995
• Issued: 09/09/1997
• Est. Priority Date: 06/06/1995
• Status: Expired due to Term

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Prince (Wellman Holdings, Inc.)
• Inventors: Geerlings, Steven L., Suman, Michael J.
• Primary Examiner(s): Bennett, G. Bradley
• Application Number:
  US08/467,624
• Time in Patent Office: 826 Days
• Field of Search: 33/355 R, 33/356, 33/357, 33/361, 340/438, 340/440, 340/425.5, 340/458, 340/457, 340/461
• US Class Current: 33/356
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

A compass circuit has a magnetic field sensor adapted to be positioned in a vehicle near a source of varying magnetic fields. A detector is coupled to the compass circuit for providing a signal applied to the compass circuit which responds for displaying the compass heading prior to the magnetic field disturbance to provide accurate heading information. In a preferred embodiment, the detector senses when a door is opened and the compass heading prior to the opening of the door is displayed.

Claims

1. A vehicle compass correction circuit for correcting for vehicle generated internal 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; and

a detector for providing signals representing the closure state of at least one vehicle closure member, said detector coupled to said compass circuit to provide such status information and wherein said compass circuit responds to said signals to display a vehicle heading unaffected by the opening of a vehicle closure member.

2. The electrical circuit as defined in claim 1 wherein said closure member is a door and said detector includes a courtesy light switch for actuation by a vehicle door.

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

4. A vehicle compass circuit for correcting for varying interfering magnetic fields generated by the use of a vehicle, said circuit comprising:

a magnetic field sensor for providing signals representative of the vehicle heading;

a display for displaying this vehicle heading;

a microcontroller coupled to said sensor and to said display for displaying direction indicating information detected by said magnetic field sensor; and

a source of signals coupled to said microcontroller to provide an indication that the vehicle'"'"'s internal magnetic field has changed without a change in vehicle heading, wherein said microcontroller responds to said signals to display the last heading prior to this change in the vehicle'"'"'s internal magnetic field.

5. The electrical circuit as defined in claim 4 wherein said source of signals comprises a detector circuit for detecting vehicle internal magnetic field changes.

6. The electrical circuit as defined in claim 5 wherein said detector circuit includes a door actuated switch.

7. The electrical circuit as defined in claim 4 wherein said source of signals comprises a courtesy light signal provided when a door is opened.

8. A vehicle compass including a circuit for correcting temporary changing levels of local magnetic field disturbances caused by operation of 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 detector providing signals identifying the magnetic field disturbance;

a display for displaying the detected vehicle heading; and

a microcontroller coupled to said sensor, to said detector and to said display and responsive to signals from said detector for displaying the last vehicle heading prior to a magnetic field disturbance.

9. The compass as defined in claim 8 wherein the source of magnetic field disturbance is movement of a vehicle door.

10. The compass as defined in claim 9 wherein said detector includes a door actuated switch.

11. A method of preventing erroneous electronic compass heading displays when a door of a vehicle is opened comprising:

providing an electronic compass for a vehicle;

detecting when a vehicle door has been opened; and

after the door is opened, displaying the last known vehicle heading prior to the vehicle door being opened.

12. The method as defined in claim 11 wherein said detecting step includes sensing the voltage of a door actuated courtesy lamp circuit.