Solid state compass

• US 4,373,271 A
• Filed: 12/11/1980
• Issued: 02/15/1983
• Est. Priority Date: 12/11/1980
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Nitz, Larry T.
• Primary Examiner(s): Martin, Jr., William D.
• Application Number:
  US06/215,268
• Time in Patent Office: 796 Days
• Field of Search: 324/251, 324/240, 324/247, 324/246, 324/260, 33/361, 33/362
• US Class Current: 33/361
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26

Abstract

The magnetic field strengths in two perpendicularly oriented ferromagnetic core members are converted to voltages and summed to form a composite field strength voltage. The core members are mounted in a vehicle and the slope polarity and amplitude of the composite field strength voltage are used to determine the heading of the vehicle.

Claims

1. A motor vehicle compass comprising:

perpendicularly oriented ferromagnetic core members mounted in a predetermined relationship with respect to the heading of said vehicle;

sensing means associated with each of said core members for providing an electrical signal determined as a function of the magnetic field strength therein, the magnetic field strength in said core members varying as a function of the orientation of said core members relative to the earth'"'"'s magnetic field;

means responsive to said sensing means for summing said electrical signals to form a composite field intensity signal;

means responsive to the relative magnitudes of said electrical signals and to the amplitude of said composite signal for developing a direction signal indicative of the heading of the vehicle; and

means responsive to said direction signal for visually displaying the heading of the vehicle.

2. A motor vehicle compass comprising:

perpendicularly oriented ferromagnetic core members mounted in a predetermined relationship with respect to the heading of said vehicle;

means for establishing a reference magnetic field in each of said core members;

sensing means associated with each of said core members including a Hall Effect device for providing an electrical voltage determined in accordance with the magnetic field strength in a respective core member, the magnetic field strength in said core member varying as a function of the alignment of said core member relative to the earth'"'"'s magnetic field;

means responsive to said sensing means for summing said electrical voltages to form a composite voltage;

means responsive to the relative magnitudes of said electrical voltages and to the amplitude of said composite voltage for developing a direction signal indicative of the heading of the vehicle; and

means responsive to said direction signal for displaying the heading of the vehicle.

3. A vehicle compass comprising:

perpendicularly oriented ferromagnetic core members mounted in a predetermined relationship with respect to the heading of said vehicle;

sensing means associated with each of said core members for providing an electrical signal determined as a function of the magnetic field strength therein, the magnetic field strength in said core members varying as a function of the alignment of said core members relative to the earth'"'"'s magnetic field;

means responsive to said sensing means for summing said electrical signals to form a composite field intensity signal;

means for retrieving a previously determined direction signal as a function of the amplitude of said composite signal;

means responsive to the relative magnitudes of said electrical signals for developing a slope signal indicative of the slope polarity of said composite signal;

means for decoding said slope signal and said direction signal to develop a heading signal, said slope signal being used to resolve ambiguity in said direction signal; and

means responsive to said heading signal for displaying the heading of the vehicle.