Rotary encoder with shielded magnet

1. A rotary encoder, comprising:

a permanent magnet arrangement including at least one permanent magnet, which is rotatable with respect to a rotation axis;

a soft magnetic sleeve encompassing the rotation axis and thus the permanent magnet arrangement for shielding against external magnetic fields;

a shaft, which is rotatable with respect to a rotation axis and mechanically coupled to the permanent magnet arrangement to ensure a common rotation,

wherein the at least one permanent magnet includes a through-hole, which extends along the rotation axis, so that the permanent magnet fully extends around the rotation axis, and

wherein the soft magnetic sleeve is slipped over a longitudinally extending portion of the shaft, wherein the longitudinally extending portion has a uniform cross-section, and

wherein the shaft is adjoined to the permanent magnet arrangement; and

a magnetic field sensor to measure a magnetic field associated with the permanent magnet arrangement.

2. The rotary encoder of claim 1 , wherein the shaft includes a cavity, which extends into the shaft from a front side of the shaft along the rotation axis.

3. The rotary encoder of claim 2 , wherein the permanent magnet arrangement has an outer diameter and the cavity included in the shaft has an axial length equal to or greater than the outer diameter of the permanent magnet arrangement.

4. The rotary encoder of claim 1 , wherein the at least one permanent magnet is substantially rotationally symmetric with respect to the rotation axis.

5. The rotary encoder of claim 1 , wherein the permanent magnet arrangement is substantially symmetric with respect to a symmetry plane, to which the rotation axis is perpendicular.

6. The rotary encoder of claim 1 , wherein the permanent magnet arrangement has a centroid that is located within the through-hole at the rotation axis.

7. A rotary encoder, comprising:

a permanent magnet arrangement including at least one permanent magnet, which is rotatable with respect to a rotation axis;

a soft magnetic sleeve encompassing the rotation axis and thus the permanent magnet arrangement for shielding against external magnetic fields;

wherein the at least one permanent magnet includes a through-hole, which extends along the rotation axis, so that the permanent magnet fully extends around the rotation axis,

wherein the sleeve has a collar, which is inwardly bent to the rotation axis, and wherein a front side of the permanent magnet arrangement adjoins a back side of the collar, and

a magnetic field sensor to measure a magnetic field associated with the permanent magnet arrangement.

8. The rotary encoder of claim 7 , wherein the at least one permanent magnet is substantially rotationally symmetric with respect to the rotation axis.

9. The rotary encoder of claim 7 , wherein the permanent magnet arrangement is substantially symmetric with respect to a symmetry plane, to which the rotation axis is perpendicular.

10. A rotary encoder comprising:

a permanent magnet arrangement including at least one permanent magnet, which is rotatable with respect to a rotation axis and includes a through-hole, which extends along the rotation axis, so that the permanent magnet fully extends around the rotation axis;

a soft magnetic sleeve encompassing the rotation axis and thus the permanent magnet arrangement for shielding external magnetic fields;

a shaft, which is rotatable with respect to the rotation axis and adjoined to the permanent magnet arrangement to ensure a common rotation, and

a magnetic field sensor located within the through-hole on the rotation axis,

wherein the permanent magnet arrangement is substantially symmetric with respect to a symmetry plane, to which the rotation axis is perpendicular, and

wherein the magnetic field sensor is located at the intersection of the symmetry plane and the rotation axis.

11. The rotary encoder of claim 10 ,

wherein the permanent magnet arrangement has a centroid that is located within the through-hole, and

wherein the magnetic field sensor is located in the centroid.

12. The rotary encoder of claim 10 , wherein the at least one permanent magnet is substantially rotationally symmetric with respect to the rotation axis.

13. The rotary encoder of claim 10 , wherein the permanent magnet arrangement is substantially symmetric with respect to a symmetry plane, to which the rotation axis is perpendicular.

14. The rotary encoder of claim 10 , wherein the permanent magnet arrangement has a centroid that is located within the through-hole at the rotation axis.

15. The rotary encoder of claim 10 , wherein the magnetic field sensor includes one or more sensor elements included in one chip package.

16. The rotary encoder of claim 10 , wherein the soft magnetic sleeve is slipped over a longitudinally extending portion of the shaft, wherein the longitudinally extending portion has a uniform cross-section.