Electronic compass system

• US 7,379,814 B2
• Filed: 08/21/2007
• Issued: 05/27/2008
• Est. Priority Date: 03/01/2002
• Status: Expired due to Term

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Bechtel, Jon H., Ockerse, Harold C., Bugno, Mark D.
• Primary Examiner(s): Beaulieu; Yonel
• Application Number:
  US11/842,481
• Publication Number:
  US 20070288166A1
• Time in Patent Office: 280 Days
• Field of Search: 701/224, 73/17.5, 73/17.6, 702 92- 93, 318647-648, 342/357.14, 333/61
• US Class Current: 701/224
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26
• CPC Class Codes: G01C 17/30 Earth-inductor compasses
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

An electronic compass system includes a magnetic sensor circuit having at least two sensing elements for sensing perpendicular components of the Earth'"'"'s magnetic field vector. A processing circuit is coupled to the sensor circuit to filter, process, and compute a heading. The processing circuit may determine whether too much noise is present in the output signals received from said magnetic sensor circuit as a function of the relative strength of the Earth'"'"'s magnetic field vector. The magnetic sensor circuit may include three magnetic field sensing elements contained in a common integrated package having a plurality of leads extending therefrom for mounting to a circuit board. The sensing elements need not be perpendicular to each other or parallel or perpendicular with the circuit board. The electronic compass system is particularly well suited for implementation in a vehicle rearview mirror assembly.

Claims

1. A rearview mirror assembly for a vehicle, comprising:

a mirror mounting structure configured to mounting to a vehicle and having a mirror housing;

a mirror mounted in said mirror housing;

a circuit board carried by said mirror mounting structure;

a magnetic sensor circuit mounted on said circuit board for sensing at least two components of the Earth'"'"'s magnetic field vector, and for generating output signals representing the at least two sensed components, wherein said magnetic sensor circuit includes three magnetic field sensing elements contained in a common integrated package having a plurality of leads extending therefrom for mounting to said circuit board; and

a processing circuit coupled to said magnetic sensor circuit for receiving the output signals from said magnetic sensor circuit, computing a heading of the vehicle as a function of the sensed components, and generating a heading signal representing the computed heading.

2. The rearview mirror assembly of claim 1, wherein said circuit board defines a plane corresponding to a mounting surface thereof, wherein each of said magnetic field sensing elements has an axis of sensitivity, and wherein at least one of said magnetic field sensing elements is positioned such that its axis of sensitivity is oriented in one of the following two orientations:

(a) non-perpendicular and non-parallel to the plane of said circuit board, and (b) non-perpendicular to the axis of sensitivity of another one of said at least two magnetic field sensing elements.

3. The rearview mirror assembly of claim 1, wherein said processing circuit is mounted on said circuit board, said circuit board includes a connector for connecting an electrical component, and said processing circuit is configured to communicate using at least two different signal formats associated with different types of electronic components, and wherein a particular signal format used by said processing circuit to communicate with the electrical component connected to said connector is selectable.

4. The electronic compass subassembly of claim 3, wherein said electronic component is a display driver circuit.

5. The electronic compass subassembly of claim 3, wherein said electronic component is mounted on a daughter circuit board, said circuit boards each comprising a connector that electrically couples said circuit boards.

6. The electronic compass subassembly of claim 3, wherein said electronic component is a vehicle bus interface circuit.

7. An electronic compass subassembly for a vehicle, comprising:

a circuit board including a connector for connecting an electrical component; and

a processing circuit mounted on said circuit board and electrically coupled to said connector for communicating with the electrical component, wherein said processing circuit is coupled to a magnetic sensor circuit for receiving output signals representing at least two components of the Earth'"'"'s magnetic field vector, computing a heading of the vehicle as a function of the sensed components, and generating a heading signal representing the computed heading,

wherein said processing circuit is configured to communicate using at least two different signal formats associated with different types of electronic components, and wherein a particular signal format used by said processing circuit to communicate with the electrical component connected to said connector is selectable.

8. The electronic compass subassembly of claim 7, wherein said electronic component is a display driver circuit.

9. The electronic compass subassembly of claim 8, wherein said display driver circuit is mounted on a daughter circuit board, said circuit boards each comprising a connector that electrically couples said circuit boards.

10. The electronic compass subassembly of claim 9, wherein said connector of said daughter circuit board has a connector configuration that is unique for the type of display driver circuit mounted thereon.

11. The electronic compass subassembly of claim 10, wherein said processing circuit automatically selects the particular signal format used to communicate with said display driver circuit based upon the connector configuration of the connector of said daughter circuit board.

12. The electronic compass subassembly of claim 7, wherein said electronic component is mounted on a daughter circuit board, said circuit boards each comprising a connector that electrically couples said circuit boards.

13. The electronic compass subassembly of claim 12, wherein said connector of said daughter circuit board has a connector configuration that is unique for the type of electronic component mounted thereon.

14. The electronic compass subassembly of claim 13, wherein said processing circuit automatically selects the particular signal format used to communicate with said electronic component based upon the connector configuration of the connector of said daughter circuit board.

15. The electronic compass subassembly of claim 7, wherein said electronic component is a vehicle bus interface circuit.

16. A method of mounting magnetic sensing elements on a circuit board, the method comprising:

mounting a first magnetic sensing element on a first portion of the circuit board;

mounting a second magnetic sensing element on a second portion of the circuit board;

bending the second portion of the circuit board to reorient the second magnetic sensing element relative to the first magnetic sensing element; and

securing the second portion of the circuit board relative to the first portion of the circuit board to retain the reoriented positions of the first and second magnetic sensing elements.

17. The method of claim 16 and further comprising mounting a third magnetic sensing element on the first portion of the circuit board.

18. The method of claim 17, wherein the third magnetic sensing element is mounted on the first portion of the circuit board substantially perpendicular to the first magnetic sensing element.

19. The method of claim 18, wherein the second magnetic sensing element is mounted on the second portion of the circuit board and reoriented so as to be substantially perpendicular to the first and third magnetic sensing elements.

20. The method of claim 16, wherein the second magnetic sensing element is mounted on the second portion of the circuit board and reoriented so as to be substantially perpendicular to the first magnetic sensing element.

21. The method of claim 16 and further comprising:

mounting a processing circuit on the circuit board;

electrically connecting the processing circuit to the magnetic sensing elements;

providing a connector on the circuit board for connecting an electrical component; and

configuring the processing circuit to communicate using at least two different signal formats associated with different types of electronic components, and wherein a particular signal format used by the processing circuit to communicate with the electrical component connected to the connector is selectable.