Arrangement for measuring the angular position of an object

• US 20040160220A1
• Filed: 12/17/2003
• Published: 08/19/2004
• Est. Priority Date: 07/03/2001
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Wendt, Matthias
• Granted Patent: US 7,417,421 B2
• Time in Patent Office: Days
• US Class Current: 324/207.21
• CPC Class Codes: G01D 2205/73 Targets mounted eccentrically with respect to the axis of rotation
• CPC Class Codes: G01D 2205/777 Whorl-shaped profiles
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

Arrangement for measuring the angular position of an object, using planar magnetoresistive sensors (6, 9) through which an electric current flows and which are arranged in a magnetic field which is parallel to their respective planes, which magnetic field is generated by an arrangement of magnets (4, 14) rotatably journaled eccentrically on a shaft (11), the angular position of the shaft (11) corresponding to that of the object to be measured.

Claims

1. An arrangement for measuring the angular position of an object, using planar magnetoresistive sensors (6, 9) through which an electric current flows and which are arranged in a magnetic field which is parallel to a plane defined by their surface, which magnetic field is generated by an arrangement of magnets (4, 14) rotatably journaled on a shaft (11), the angular position of the shaft (11) corresponding to that of the object to be measured, characterized in that the rotationally symmetrical arrangement of magnets (4, 14) is eccentrically journaled with respect to the axis of symmetry.

3. An arrangement as claimed in claim 1 or 2, characterized in that the second magnetoresistive sensor (9) is arranged in a plane perpendicular to the plane of the first sensor (6).

4. An arrangement as claimed in claim 1, characterized in that the arrangement of magnets comprises a centrally arranged permanent magnet (4), an external ferromagnetic circuit (14) and an air gap (13) in between.

6. An arrangement as claimed in any one of the preceding claims, characterized in that the air gap of the arrangement of magnets is filled with a non-conducting material.

7. An arrangement as claimed in claim 1 or 2, characterized in that an annular magnetization in a permanent-magnetic material generates the field.

8. An arrangement as claimed in any one of the preceding claims, characterized in that the planes of the two planar magnetoresistive sensors (6, 9) are arranged parallel to the axis of rotation (11) of the object to be measured.

9. An arrangement as claimed in any one of the preceding claims, characterized in that the two magnetoresistive sensors (6, 9) are arranged on a common carrier plate (10) perpendicularly to said plate.

10. An arrangement as claimed in claim 9, characterized in that the carrier plate (10) is arranged perpendicularly to the axis of rotation (11) of the object to be measured.

11. An arrangement as claimed in any one of the preceding claims, characterized in that the magnetoresistive sensors (6, 9) form part of an integrated circuit (3).

12. An arrangement as claimed in any one of the preceding claims, characterized in that a magnetoresistive sensor (6, 9) comprises a Wheatstone bridge with four magnetoresistive resistors each.

13. An arrangement as claimed in any one of the preceding claims, characterized in that it is connected to an evaluation device.

2. An arrangement for measuring the angular position of an object, using planar magnetoresistive sensors (6, 9) through which an electric current flows and which are arranged in a magnetic field which is parallel to a plane defined by their surface, which magnetic field is generated by an arrangement of magnets (4, 14) rotatably journaled on a shaft (11), the angular position of the shaft (11) corresponding to that of the object to be measured, characterized in that the arrangement of magnets has an asymmetrical cross-section.

5. An arrangement as claimed in claim 2, characterized in that the permanent magnet (4) has a cam-shaped cross-section.