Rotation detecting device

• US 20060238190A1
• Filed: 04/04/2006
• Published: 10/26/2006
• Est. Priority Date: 04/21/2005
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ishio, Seiichiro
• Granted Patent: US 7,355,388 B2
• Time in Patent Office: Days
• US Class Current: 324/207.210
• CPC Class Codes: G01D 5/06 acting through a wall or enclosure, e.g. by bellows, by magnetic coupling
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A rotation detecting device detects rotation of a rotating object by means of a biasing permanent magnet and plural magnetoresistance sensors. The sensors are disposed along the rotation direction of the rotating object to convert magnetic vectors of a magnetic field to a plurality of sensor signals. A selection circuit is connected to the magnetoresistance sensors and selects one of the sensor signals whose magnitude is the largest.

Claims

1. A rotation detecting device for detecting rotation of a rotating object comprising:

a biasing permanent magnet for providing a biasing magnetic field that extends toward the rotation object;

a plurality of magnetoresistance sensors, disposed along the rotation direction of the rotating object in parallel with each other, for converting magnetic vectors of the magnetic field to a plurality of sensor signals; and

output means, connected to said magnetoresistance sensors, for outputting a rotation signal based on a selected signal that are selected from the sensor signals.

2. The rotation detecting device as claimed in claim 1, wherein the selected signal has a largest magnitude of the other sensor signals.

3. The rotation detecting device as claimed in claim 2, wherein:

each of said magnetoresistance sensors comprises a pair of magnetoresistance elements each of which is disposed to provide one of two component signals having phase reversed to the other, thereby providing a difference between the two component signals as one of the sensor signals

said output means includes a selection circuit for selecting as the selected signal from the sensor signals one of the sensor signals whose magnitude is the largest.

4. The rotation detecting device as claimed in claim 1 further comprising an elongated chip mount having surfaces that are perpendicular to the rotation axis of the rotating object, wherein said magnetoresistance sensors are fixed to said surfaces.

5. The rotation detecting device as claimed in claim 4, wherein said chip mount is a lead frame for transmitting the rotation signal.

6. The rotation detecting device as claimed in claim 4, further comprising a plurality of sensor chips fixed to said chip mount, wherein said magnetoresistance sensors are formed on the surfaces.

7. The rotation detecting device as claimed in claim 1, wherein:

said biasing permanent magnet has a hollow cylindrical shape; and

said magnetoresistance sensors are disposed inside said biasing permanent magnet.

8. The rotation detecting device as claimed in claim 7, further comprising a resinous mold member filled inside said biasing permanent magnet to cover said magnetoresistance sensors.

9. A rotation detecting device for providing a rotation signal relating to rotation of a rotating object via magnetic teeth formed around the periphery thereof, said rotation detecting device comprising:

a hollow cylindrical biasing permanent magnet magnetized to provide a biasing magnetic field toward the magnetic teeth of the rotation object;

a pair of magnetoresistance sensors, disposed inside said biasing permanent magnet in parallel with each other along the rotation direction of the rotating object, for providing a pair of sensor signals; and

means for selecting from the sensor signals one of the sensor signals whose magnitude is larger than the other.

10. The rotation device as claimed in claim 9, wherein each of said magnetoresistance sensors includes a pair of series-connected magnetoresistance elements each of which is disposed to provide a component signal having phase reversed to the other, thereby providing a difference between the two component signals as one of the sensor signals.

11. The rotation device as claimed in claim 10, wherein said means for selecting comprises a selection circuit connected to said magnetoresistance sensors.

12. A rotation detecting device for providing a rotation signal relating to rotation of a rotating object via magnetic teeth formed around the periphery thereof, said rotation detecting device comprising:

a hollow cylindrical biasing permanent magnet magnetized to provide a biasing magnetic field toward the magnetic teeth of the rotation object;

a pair of sensor chips, disposed inside said biasing permanent magnet in parallel with each other along the rotation direction of the rotating object, each of said sensor chips including a plurality of magnetoresistance sensors formed thereon at different positions in parallel to each other so that each sensor chip provides a pair of sensor signals; and

means for selecting from the sensor signals of said sensors formed at corresponding positions on the pair of sensor chips a selected pair of the sensor signals whose magnitude is larger than the other; and

means for calculating a difference between the selected pair of sensor signals.

13. The rotation detecting device as claimed in claim 12, wherein each of said magnetoresistance sensor comprises a pair of series-connected magnetoresistance elements, each of said magnetoresistance elements being disposed to provide a component signal having phase reversed to the other to provide a difference between the two component signals as one of the sensor signals.

14. A rotation detecting device for providing a rotation signal relating to rotation of a rotating object via magnetic teeth formed around the periphery thereof, said rotation detecting device comprising:

a hollow cylindrical biasing permanent magnet magnetized to provide a biasing magnetic field extending toward the magnetic teeth of the rotation object;

a plurality of magnetoresistance sensors, disposed inside said biasing permanent magnet in parallel with each other along the rotation direction of the rotating object, for providing a plurality sensor signals; and

means for selecting from the sensor signals one of the plurality of sensor signals whose magnitude is the largest.

15. The rotation detecting device as claimed in claim 14, wherein each of said magnetoresistance sensor comprises a pair of series-connected magnetoresistance elements, each of said magnetoresistance elements being disposed to provide a component signal having phase reversed to the other to provide a difference between the two component signals as one of the sensor signals.