Sensing methods and systems for hall and/or MR sensors

• US 6,759,843 B2
• Filed: 11/15/2002
• Issued: 07/06/2004
• Est. Priority Date: 11/15/2002
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Furlong, Gregory R.
• Primary Examiner(s): Patidar, Jay
• Application Number:
  US10/295,746
• Publication Number:
  US 20040095129A1
• Time in Patent Office: 599 Days
• Field of Search: 324/207.12, 324/207.2, 324/207.21, 324/207.24, 324/207.25, 324/207.26, 324/251, 324/252, 338/32.R, 338/32.H, 327/510, 327/511
• US Class Current: 324/207.2
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

Magnetic sensing methods and systems are disclosed. A minimum magnetic signal output and a maximum magnetic signal output can be detected utilizing a sensor comprising a peak detector circuit associated with a filter averaging circuit and one or more magnetic elements (e.g., a Hall element and/or magnetoresistive bridge). An average magnetic signal output can then be determined utilizing the filter averaging circuit when a target begins to rotate in front of the sensor.

Claims

1. A magnetic sensing method, said method comprising the steps of:

detecting a minimum magnetic signal output and a maximum magnetic signal output utilizing a sensor comprising a peak detector circuit associated with a filter averaging circuit and at least one magnetic element thereof; and

determining an average magnetic signal output utilizing said filter averaging circuit when a target begins to rotate in front of said sensor, wherein said filter averaging circuit stabilizes when an area of a curve above said average magnetic signal output is equal to an area under said curve.

2. The method of claim 1 further comprising the step of:

automatically switching said sensor from a peak detector circuit mode to a filter averaging circuit mode at a specified frequency.

3. The method of claim 1 further comprising the step of:

establishing a sensor switching level approximately halfway between said minimum magnetic signal output and said maximum magnetic signal output.

4. The method of claim 1 wherein said at least one magnetic element comprises a Hall element.

5. The method of claim 1 wherein said at least one magnetic element comprises a magnetoresistive bridge.

6. The method of claim 1 further comprising the step of:

coupling said peak detector circuit with at least one biasing magnet.

7. The method of claim 1 wherein said sensor comprises a camshaft position sensor.

8. The method of claim 1 wherein said sensor comprises a crankshaft position sensor.

9. The method of claim 1 wherein said peak detector circuit comprises BICMOS circuitry.

10. The method of claim 1 wherein said filter averaging circuit comprises BICMOS circuitry.

11. A magnetic sensing system, comprising:

a sensor for detecting a minimum magnetic signal output and a maximum magnetic signal output, wherein said sensor comprises a peak detector circuit associated with a filter averaging circuit and at least one magnetic element thereof; and

a filter averaging circuit for determining an average magnetic signal output when a target begins to rotate in front of said sensor, wherein said filter averaging circuit stabilizes when an area of a curve above said average magnetic signal output is equal to an area under said curve.

12. The system of claim 11 further comprising:

switching mechanism for automatically switching said sensor from a peak detector circuit mode to a filter averaging circuit mode at a specified frequency.

13. The system of claim 11 further comprising the step of:

a sensor switching level established approximately halfway between said minimum magnetic signal output and said maximum magnetic signal output.

14. The system of claim 11 wherein said at least one magnetic element comprises a Hall element.

15. The system of claim 11 wherein said at least one magnetic element comprises a magnetoresistive bridge.

16. The system of claim 11 further comprising the step of:

coupling said peak detector circuit with at least one biasing magnet.

17. The system of claim 11 wherein said sensor comprises a camshaft position sensor.

18. The system of claim 11 wherein said sensor comprises a crankshaft position sensor.

19. The system of claim 11 wherein said peak detector circuit comprises BICMOS circuitry and wherein said filter averaging circuit comprises BICMOS circuitry.

20. A magnetic sensing system, comprising:

a sensor for detecting a minimum magnetic signal output and a maximum magnetic signal output, wherein said sensor comprises a peak detector circuit associated with a filter averaging circuit and at least one magnetic element thereof, such that said peak detector circuit comprises BICMOS circuitry and is coupled with at least one biasing magnet thereof;

a filter averaging circuit comprising BICMOS circuitry for determining an average magnetic signal output when a target begins to rotate in front of said sensor, wherein said filter averaging circuit stabilizes when an area of a curve above said average magnetic signal output is equal to an area under said curve; and

a switching mechanism for automatically switching said sensor from a peak detector circuit mode to a filter averaging circuit mode at a specified frequency, wherein a sensor switching level is established approximately halfway between said minimum magnetic signal output and said maximum magnetic signal output.