Rotary encoder for determining the angular position between two rotating components

1. A rotary encoder ( 1 ) for detecting the angular position of a first shaft ( 24 ), with a first mark ( 5 ) which is rotatable with the first shaft ( 24 ), in relation to a second shaft ( 21 ) rotating in a fixed ratio to the first shaft ( 24 ), said second shaft ( 21 ) including a second mark ( 3 ) which is rotatable with the second shaft ( 21 ), said rotary encoder comprising:

an angular position detector, configured for detecting the angular position of the second shaft ( 21 ) and a coincidence of angle of rotation detector, configured for detecting a coincidence of the angle of rotation of the first mark ( 5 ) in relation to the second mark ( 3 ), wherein said coincidence of angle of rotation detector includes a sensor, wherein one of the first mark ( 5 ) and the second mark ( 3 ) is said sensor, and wherein said sensor is configured for detecting a presence and/or proximity of the other of said first mark ( 5 ) or second mark ( 3 ) in relation to said sensor.

2. The rotary encoder according to claim 1 , characterised in that the angular position detector for detecting the angular position of the second shaft ( 21 ) comprises a third mark ( 2 ) which is rotatable with the second shaft ( 21 ) and a fixed position fourth mark ( 4 ), and wherein the rotary encoder further includes an evaluator ( 25 ), responsive to at least said fixed position fourth mark ( 4 ), and configured for detecting a passage of the third mark ( 2 ) through a vicinity of the fourth mark ( 4 ).

3. The rotary encoder according to claim 2 , characterised in that the fixed position fourth mark ( 4 ) is a sensor ( 8 ) and the third mark ( 2 ) is configured to be detected by the sensor ( 8 ), and wherein the output from the sensor ( 8 ) is a periodic function of an angle of rotation of the second shaft ( 21 ), and wherein a base period of the periodic function corresponds to one rotation of the second shaft ( 21 ).

4. The rotary encoder according to claim 1 , characterised in that the angular position detector for detecting the angular position of the second shaft ( 21 ) comprises an absolute encoder.

5. The rotary encoder according to claim 1 , characterised in that the first and second shafts ( 24 , 21 ) are rotatably coupled by means of a gear ( 31 ).

6. The rotary encoder according to claim 5 , characterised in that the gear ( 31 ) is a form-fitting gear.

7. The rotary encoder according to claim 5 , characterised in that the gear ( 31 ) is a reduction gear.

8. The rotary encoder according to claim 5 , characterised in that the gear ( 31 ) is a ring gear.

9. The rotary encoder according to claim 5 , characterised in that the first and second shafts ( 24 , 21 ) are coaxially aligned and have end faces, arranged opposite one another, on which the first mark and the second mark ( 5 , 3 ) are arranged respectively.

10. The rotary encoder according to claim 3 , characterised in that the output from the sensor ( 8 ) is the periodic function of the angle of rotation (ω 1 ) of the second shaft ( 21 ), and wherein one rotation of the second shaft ( 21 ) corresponds to |i−1|base periods of the function.

11. The rotary encoder according to claim 1 , further including an evaluator ( 25 ) configured for coincidence of angle of rotation detector, and for receiving a passage signal (S D ) from a passage detector, said passage detector configured for detecting a passage of the third mark ( 2 ) through a vicinity of the fourth mark ( 4 ), and wherein said evaluator ( 25 ) is configured for determining an angle position of said first shaft ( 24 ) and said second shaft ( 21 ) on the basis of an angle of rotation (α, β) covered between reception of the coincidence signal (S K ) and reception of the passage signal (S D ).

12. The rotary encoder according to claim 1 , further including a sensor ( 11 , 14 ) for detecting a relative angle of rotation of the first and/or the second shaft ( 21 , 24 ).

13. A robot ( 100 ) with a rotary encoder ( 1 ) according to claim 5 , characterised in that the robot ( 100 ) comprises at least two arm sections ( 101 - 109 ) which can be swivelled relative to one another, one arm section of which is connected in a rotationally fixed manner to the first shaft ( 24 ) and the other arm section being connected in a rotationally fixed manner to a housing ( 20 ) of the gear ( 31 ).

14. The rotary encoder according to claim 1 , characterised in that, one of the first mark and the second mark ( 5 , 3 ) is a magnet ( 7 ) and the other one of the first mark and the second mark ( 3 , 5 ) is said sensor, said sensor comprising a magnetic field sensor ( 9 ).

15. A method for detecting the angular position of a first shaft ( 24 ) which is coupled via a gear ( 31 ) to a second shaft ( 21 ), so that one rotation of the first shaft ( 24 ) corresponds to i rotations of the second shaft ( 21 ), said method comprising the steps of:

rotating the first and second shafts ( 21 , 24 );

detecting a passage of a third mark ( 2 ) rotating with the second shaft ( 21 ) through a reference position;

detecting a coincidence of angle of rotation between a second mark ( 3 ) rotating with the second shaft ( 21 ) and a first mark ( 5 ) rotating with the first shaft ( 24 ), wherein one of the first and second marks ( 5 , 3 ) is a sensor configured for detecting a presence and/or proximity of the other of the first and second marks ( 5 , 3 ) in relation to said sensor;

determining an angle of rotation (α, β) covered between the passage though the reference position and the coincidence of angle of rotation; and

determining the angular position on the basis of the angle of rotation (α, β) covered.