Rotation detecting device

• US 20060097717A1
• Filed: 11/01/2005
• Published: 05/11/2006
• Est. Priority Date: 11/02/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kato, Yukihiro, Tokuhara, Minoru
• Granted Patent: US 7,253,613 B2
• Time in Patent Office: Days
• US Class Current: 324/207.25
• CPC Class Codes: G01D 18/001 Calibrating encoders
• CPC Class Codes: G01D 3/022 having an ideal characteristic, map or correction data stored in a digital memory
• 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: G01D 5/2448 Correction of gain, threshold, offset or phase control
• CPC Class Codes: G01P 3/487 delivered by rotating magnets

Abstract

A rotation detecting device for detecting a rotating object includes a housing having a bearing and an mounting surface, a rotor member having magnetic peripheral portion and a rotary shaft that is supported by the bearing, a biasing permanent magnet for providing magnetic field around the mounting surface and the magnetic peripheral portion, an IC sensor chip including plural magnetic sensor elements disposed on the mounting surface to provide a sensing signal related to change in magnetic field around the sensor elements, and an IC signal processing chip that provides a rotation signal according to the sensing signal. In this device, the bearing and the mounting surface are integrally formed into the housing at a prescribed distance to secure an unchanged air gap distance.

Claims

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

a housing having a bearing and an mounting surface;

a rotor member having magnetic peripheral portion and a rotary shaft that is connectable to the rotating object and is supported by the bearing;

a biasing permanent magnet for providing magnetic field around said mounting surface and the magnetic peripheral portion;

a semiconductor chip, including plural magnetic sensor elements disposed on said mounting surface, for providing a sensing signal related to change in magnetic field around it;

means for providing a rotation signal according to the sensing signal,

wherein the bearing and the mounting surface are integrally formed with said housing at a prescribed distance.

2. The rotation detecting device as claimed in claim 1, wherein said semiconductor chip further comprises a signal processing circuit that includes a nonvolatile memory for storing adjusting data to adjust a variation of the sensing signal caused by the prescribed distance.

6. The rotation detecting device as claimed in claim 2, wherein said conductor chip further comprises a data-input terminal extending from the nonvolatile memory for inputting data from outside after said conductor chip is mounted on the mounting surface.

7. The rotation detecting device as claimed in claim 1 wherein said housing is made of resinous material.

3. The rotation detecting device as claimed in claim 3, wherein the magnetic sensor element comprises a magnetoresistance element.

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

the magnetic peripheral portion comprises a gear-teeth type member; and

the mounting surface is formed perpendicular to the rotary shaft on an imaginary plane extending through the axially middle portion of the rotor member.

5. The rotation detecting device as claimed in claim 4, wherein said biasing permanent magnet has a cylindrical shape surrounding the semiconductor chip.

8. A rotation detecting device for detecting a rotating object comprising:

a pair of magnetic sensor units disposed to apart from each other at a first pitch to provide magnetic vector detection signals;

a biasing permanent magnet;

a rotor member having first means for changing magnetic field around said pair of magnetic sensor units, said means having a plurality of members on the periphery of said rotor member each of which is disposed at second pitch from another to face said magnetic sensor units at a close distance; and

second means for comparing the detection signals with a threshold level to provide a binary signal, wherein the first pitch is equal to the second pitch.

9. The rotation detecting device for detecting a rotation object as in claim 8, further comprising an offset adjusting circuit for removing an offset component included in the magnetic vector detecting signals.

10. The rotation detecting device as in claim 9, wherein said offset adjusting circuit comprises a coupling capacitor and voltage dividing resistors.

11. The rotation detecting device as claimed in claim 8, further comprising a differential amplifier connected to said pair of magnetic sensor units.

12. The rotation detecting device as claimed in claim 8, wherein the first means comprises a gear type magnetic rotor having a plurality of teeth on the periphery thereof.

13. The rotation detecting device as claimed in claim 8, wherein the first means comprises a magnetic member having a plurality of magnetic poles of a permanent magnet.

14. The rotation detecting device as claimed in claim 8, wherein said magnetic sensor unit comprises a magnetoresistance element.

15. The rotation detecting device as claimed in claim 8, wherein said magnetic sensor unit comprises a hall element.