Sensor device to record speed and motion direction of an object, especially rotational speed and direction of a rotating object

• US 20010009367A1
• Filed: 02/22/2001
• Published: 07/26/2001
• Est. Priority Date: 02/26/1999
• Status: Abandoned Application

• Current Assignee: Dieter Seitzer, Klemens Gintner
• Original Assignee: Dieter Seitzer, Klemens Gintner
• Inventors: Gintner, Klemens, Seitzer, Dieter
• Application Number:
  US09/790,842
• Publication Number:
  US 20010009367A1
• Time in Patent Office: Days
• US Class Current: 324/207.21
• CPC Class Codes: G01P 13/045 with speed indication
• CPC Class Codes: G01P 3/487 delivered by rotating magnets

Abstract

A sensor device to record the speed and motion direction of an object, especially rotational speed and direction of a rotating object, based on the magnetoresistive effect, is provided with a magnetic field generator (2, 15) coupled to object (1), which generates a locally and time-defined varying reference magnetic field (H), with two magnetic field sensors (SE1, SE2) made of a magnetoresistive material, which are positioned at a stipulated spacing (Δy) from each other relative to magnetic field generator (2, 15) so that they are traversed by magnetic field components (H₁, H₂) of the reference field (H) that are phase shifted relative to each other, in which the phase shift ΔΦ is not equal to an integer multiple of 90°, and with a signal processing circuit (5), which records the magnetoresistive resistance (R_MR1, R_MR2) of the magnetic field sensors (SE1, SE2) dependent on the magnetic field components (H₁, H₂) in the magnetic field sensors (SE1, SE2) and generates from it electrical signals representative of the rotation speed and direction (U_s).

Claims

1. Sensor device for determination of speed and motion direction of an object, especially rotational speed and direction of a rotating object based on the magnetoresistive effect with

a magnetic field generator (2, 15) coupled to the object (1), which generates a locally and time-defined varying reference magnetic field (H),

two magnetic field sensors (SE1, SE2) made of a magnetoresistive material, which are positioned at a stipulated spacing (Δ

y) relative to each other relative to magnetic field generators (2, 15) so that they are traversed by magnetic field components (H₁, H₂) of reference field (H) that are phase shifted relative to each other, in which the phase shift (Δ

Φ

) is not equal to a whole number multiple of 90°

, and

a signal processing circuit (5), which determines the magnetoresistive resistance (R_MR1, R_MR2) of magnetic field sensors (SE1, SE2) dependent on the magnetic field components (H₁, H₂) in the magnetic field sensors (SE1, SE2) and generates from it electrical signals (U_s) representative of the speed and motion direction, especially rotational speed and direction of object (1), characterized by the fact that the signal processing circuit (5) has a voltage difference formation circuit (6) to form the difference (U_d) of the magnetic field-dependent voltages (U₁, U₂) diminishing on the magnetic field sensors (SE1, SE2) and a digitization circuit (8) connected after the voltage difference formation circuit (6) for the difference voltage (U_d), in which the pulse duty factor of the digital signal (U_s) generated by the digitization circuit (8) is evaluable by an evaluation circuit as a criterion for rotational direction (D1, D2) of object (1).

2. Sensor device according to

claim 1

, in which the magnetic field generator is a multipole wheel (2) with alternating magnetic poles (N, S) that generate an essentially sinusoidally varying magnetic field (H) around the wheel periphery.

3. Sensor device according to

claim 1

, in which the magnetic field generator is a generator wheel (15) rotating in the field of a permanent magnet (16) with a profiling (14) that varies the magnetic field (H).

4. Sensor device according to one of the

claims 1

to

3

, in which the two mag-netic sensors (SE1, SE2) are positioned essentially parallel on a common chip carrier (3).

5. Sensor device according to one of the

claims 1

to

4

, in which the two magnetic field sensors (SE1, SE2) traversed by a constant current (I_MR) are electrically connected in series.

6. Sensor device according to one of the

claims 1

to

5

, in which a switchable current source (9) for signal transmission in the two-conductor technique, controlled by the digital signal (U_s) of digitization circuit (8) is connected after signal processing circuit (5).

7. Sensor device according to one of the

claims 1

to

6

, in which the magnetic field sensors (SE1, SE2) are arranged with the signal processing circuit (5) on a common chip carrier (3).

8. Sensor device especially according to one of the

claims 1

to

7

, in which each maagnetic field sensor (SE1, SE2) is provided with a current conductor (A11, A12) to conduct an auxiliary current (I_k1, I_k2), which generates in the corresponding magnetic field sensor (SE1, SE2) a constant magnetic field (H_Ik1, H_Ik2) superimposed on the magnetic field (H) being determined.

9. Sensor device according to

claim 8

, in which the current conductor (A11, A12) is arranged loop-like to generate the constant magnetic field.

10. Sensor device according to one of the

claims 1

to

9

, in which the magnetic field generator (2′

) is provided with opposite magnetic poles (N1, N2, N3;

S1, S2, S3) to recognize the absolute position of generator (2′

).

11. Sensor device especially according to one of the

claims 1

to

10

, in which the magnetic field sensors (SE1, SE2) determine the signal trend during passage of a magnetic pole (N) of magnetic field generator (17) with high time resolution to recognize the absolute position of generator (17).

12. Sensor device according to

claim 11

, in which the magnetic field generator includes a single permanent magnet (17).