SYSTEM THAT OBTAINS A SWITCHING POINT WITH THE ENCODER IN A STATIC POSITION

• US 20100072988A1
• Filed: 09/22/2008
• Published: 03/25/2010
• Est. Priority Date: 09/22/2008
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hammerschmidt, Dirk, Ausserlechner, Udo
• Granted Patent: US 8,253,413 B2
• Time in Patent Office: Days
• US Class Current: 324/207.250
• CPC Class Codes: G01D 5/14 influencing the magnitude of a current or voltage
• CPC Class Codes: G01D 5/142 using Hall-effect devices measuring magnetic variables using Hall-effect or other galvanomagnetic devices G01R33/06
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/095 extraordinary magnetoresistance sensors
• CPC Class Codes: G01R 33/096 anisotropic magnetoresistance sensors
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• CPC Class Codes: H03M 1/202 by interpolation
• CPC Class Codes: H03M 1/28 with non-weighted coding

Abstract

A system including an encoder, multiple sensing elements and control logic. The encoder has a pole pitch and is configured to rotate in a direction of rotation. The multiple sensing elements are situated along the direction of rotation and span at least half the length of the pole pitch. The control logic is configured to receive signals from the multiple sensing elements based on the encoder in a static position and obtain a switching point based on the signals.

Claims

1. A system comprising:

an encoder having a pole pitch and configured to rotate in a direction of rotation;

multiple sensing elements situated along the direction of rotation and spanning at least half the length of the pole pitch; and

control logic configured to receive signals from the multiple sensing elements based on the encoder in a static position and obtain a switching point based on the signals.

2. The system of claim 1, wherein the encoder includes magnetic poles of substantially the same length in the direction of rotation around the circumference of the encoder.

3. The system of claim 1, wherein the encoder includes at least one of teeth of substantially the same length and holes of substantially the same length in the direction of rotation around the circumference of the encoder.

4. The system of claim 1, wherein the control logic is configured to adjust the switching point based on minimum and maximum signals obtained from the multiple sensing elements via rotation of the encoder.

5. The system of claim 1, wherein the encoder includes encoder segments and signal edges are provided based on the lengths of the encoder segments and the control logic is configured to add delays to the signal edges based on the lengths of the encoder segments to provide a corrected signal.

6. The system of claim 1, wherein the encoder includes encoder segments and signal edges are provided based on the lengths of the encoder segments and the control logic shifts a switching point spatial reference in the multiple sensing elements to provide a corrected signal.

7. The system of claim 1, wherein the control logic interpolates between the signals from adjacent sensing elements to provide a smaller pitch than the pitch between the adjacent sensing elements.

8. A system comprising:

an encoder having encoder segments of different lengths and configured to rotate in a direction of rotation;

multiple sensing elements situated along the direction of rotation and configured to provide a series of signals based on rotation of the encoder; and

control logic configured to receive the series of signals and provide subtics between a last signal in the series of signals and a first signal in a next series of signals.

9. The system of claim 8, wherein the control logic provides subtics based on the series of signals and measurement of velocity of the rotation of the encoder.

10. The system of claim 8, wherein the control logic provides subtics based on the series of signals and measurement of at least one of acceleration and change in acceleration of the rotation of the encoder.

11. The system of claim 8, wherein the control logic provides subtics based on the series of signals and averages of measurements of at least one of velocity, acceleration and change in acceleration of the rotation of the encoder.

12. The system of claim 8, wherein the control logic encodes an output signal including the subtics via one of manchester coding and multilevel coding.

13. A system comprising:

an encoder configured to rotate in a direction of rotation via an axis of rotation;

a sensor comprising;

a first sensing element; and

a second sensing element, wherein the first sensing element is situated radially further from the axis of rotation than the second sensing element.

14. The system of claim 13, wherein the first sensing element and the second sensing element are situated along the same radius from the axis of rotation.

15. The system of claim 13, comprising a third sensing element, wherein the third sensing element is situated radially further from the axis of rotation than the second sensing element.

16. The system of claim 13, wherein the encoder has a pole pitch and comprising:

pairs of sensing elements situated along the direction of rotation and including a first pair of sensing elements and a second pair of sensing elements spaced apart less than or equal to a quarter of the length of the pole pitch.

17. The system of claim 16, wherein one of the pairs of sensing elements includes the first sensing element and the second sensing element and another one of the pairs of sensing elements comprises:

a third sensing element; and

a fourth sensing element, wherein the third sensing element is situated radially further from the axis of rotation than the fourth sensing element.

18. A method of sensing comprising:

providing an encoder having a pole pitch and configured to rotate in a direction of rotation;

sensing the encoder along the direction of rotation via multiple sensing elements that span at least half the length of the pole pitch;

receiving signals from the multiple sensing elements with the encoder in a static position; and

obtaining a switching point based on the signals.

19. The method of claim 18, comprising:

adjusting the switching point based on minimum and maximum signals received from the multiple sensing elements via rotation of the encoder.

20. The method of claim 18, comprising:

receiving signal edges that are based on encoder segments; and

adding delays to the signal edges based on the lengths of the encoder segments to provide a corrected signal.

21. The method of claim 18, comprising:

receiving signal edges that are based on encoder segments; and

shifting a switching point spatial reference in the multiple sensing elements to provide a corrected signal.

22. The method of claim 18, comprising:

interpolating between the signals from adjacent sensing elements to provide a smaller pitch than the pitch between the adjacent sensing elements.

23. A method of sensing, comprising:

providing an encoder having encoder segments of different lengths;

rotating the encoder to provide a series of signals based on rotation of the encoder;

receiving the series of signals; and

providing subtics based on the series of signals and between a last signal in the series of signals and a first signal in a next series of signals.

24. The method of claim 23, wherein providing subtics comprises:

measuring at least one of velocity, acceleration and change in acceleration of the rotation of the encoder via the series of signals; and

providing subtics based on the measurement of at least one of velocity, acceleration and change in acceleration of the rotation of the encoder.

25. The method of claim 23, comprising:

encoding an output signal via one of manchester coding and multilevel coding.

26. A method of sensing comprising:

providing an encoder configured to rotate in a direction of rotation via an axis of rotation;

sensing via a first sensing element; and

sensing via a second sensing element that is radially closer to the axis of rotation than the first sensing element.

27. The method of claim 26, comprising:

sensing via pairs of sensing elements situated along the direction of rotation and including a first pair of sensing elements and a second pair of sensing elements spaced apart less than or equal to a quarter of the length of the pole pitch.

28. The method of claim 27, wherein sensing comprises:

sensing via one of the pairs of sensing elements that includes the first sensing element and the second sensing element; and

sensing via another one of the pairs of sensing elements that includes a third sensing element and a fourth sensing element that is radially closer to the axis of rotation than the third sensing element.