Encoder and sensor system having plural sensors and encoder elements for determining relative positions

Patent metadata

Field	Value
Publication number	US-9638550-B2
Application number	US-201514625318-A
Country	US
Kind code	B2
Filing date	Feb 18, 2015
Priority date	Feb 18, 2014
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

System for determining relative positions comprising an encoder having encoder elements, and a sensor unit having a first sensor and at least one second sensor. The sensor unit and the encoder are movable relative to one another and their position relative to one another is determinable by the system. The first sensor and second sensor have a sensor distance with respect to one another. The sensor furthermore has a component composed of a dimensionally stable and aging-resistant material having a coefficient of thermal expansion which, in terms of absolute value, is in a range of 0 to 5·10 −6 K −1 . The sensor distance is determinable highly precisely by the component by virtue of the component serving for the positional fixing of the sensors or by virtue of the component having a scale with the aid of which the sensor distance can be measured.

First claim

What is claimed is:

1. A system for determining relative positions comprising an encoder having encoder elements and an electronic sensor unit, wherein:
the sensor unit and encoder are movable relative to one another in a direction (E) of extent; and
the sensor unit has a first sensor and at least one further, second sensor, wherein the first sensor and the second sensor have with respect to one another a sensor distance (d) in the direction (E) of extent, said sensor distance being dimensioned in such a way that at least one encoder element is detectable by the first sensor and at least one other encoder element is detectable by the second sensor,
wherein the system has a component serving as a reference and produced from a dimensionally stable and aging-resistant material having a coefficient of thermal expansion having an absolute value in a range of 0 to at most 5×10 −6 K −1 , wherein the sensor distance (d) is determinable highly precisely by using the component.

2. The system according to claim 1 , wherein:
the component has a scale, which extends in the direction (E) of extent and defines a highly precise reference length, wherein the reference length has a relative error in the region of at most 5×10 −6 .

3. The system according to claim 1 , wherein:
the component has a scale, which extends in the direction (E) of extent and defines a highly precise reference length, wherein the reference length has a relative error in the region of at most 1×10 −6 .

4. The system according to claim 1 , wherein:
the component has a scale, which extends in the direction (E) of extent and defines a highly precise reference length, wherein the reference length has a relative error in the region of at most 5 ×10 −7 .

5. The system according to claim 2 , wherein:
the length of the scale in the direction (E) of extent is equal to the reference length, wherein the scale is arranged in such a way that, for the highly precise determination of the sensor distance (d), one scale end is detectable by the first sensor and the second scale end is detectable by the second sensor.

6. The system according to claim 1 , wherein:
the component has a scale and the scale has a position code having code elements in the direction (E) of extent and the distance between code elements serves as the reference length, wherein the component is arranged in such a manner that the code elements of the position code of the component are detectable by the first sensor and by the second sensor and the encoder with its encoder elements is arranged in such a manner that the encoder elements are also detectable by the first sensor and by the second sensor;
wherein the position code with the code elements is configured in such a way that in one step, for the highly precise determination of the sensor distance at least one code element is detectable by the first sensor and at least one other code element is detectable by the second sensor.

7. The system according to claim 1 , wherein:
the component for the highly precise determination of the sensor distance (d) serves as a substrate which fixes the first sensor and the second sensor in terms of their position with respect to one another in a manner spaced apart from one another, the dimensions of the component or the sensor distance (d) being determined highly precisely with a relative error in the region of at most 5×10 −6 , by the manufacturer before incorporation of the sensor unit, and the dimensions of the component or the sensor distance (d) measured by the manufacturer are stored in a control and evaluation unit of the system for further calculations in connection with determining relative positions.

8. The system according to claim 1 , wherein:
the component is arranged on the sensor unit and, at least a part of the component is arranged between the sensors and the encoder.

9. The system according to claim 1 , wherein:
the first sensor and the second sensor bear laterally on the component and the sensor unit has a spring and/or clamping device, by which the first sensor and the second sensor have spring force applied to them in the direction of the component and they are kept pressed against the component and/or the sensors are fixed to the component by that side by which they bear laterally on the component.

10. The system according to claim 1 , wherein:
the first sensor is divided into a first zone (zl) and a second zone (z 2 ) and the second sensor is divided into a first zone (zl) and a second zone (z 2 ), wherein the first zone (zl) of each sensor is designed for detecting encoder elements and the second zone (z 2 ) of each sensor is fixed to the component.

11. The system according to Claim 6 , wherein:
the component is arranged at one end of the encoder.

12. The system according to claim 1 , wherein:
the system has a thermometer for determining the temperature of the component and/or of the sensors,
further information about the thermal expansion behavior of the component and/or of the sensors depending on the temperature is stored in a control and evaluation unit of the system,
and the control and evaluation unit is programmed in such a way that the sensor distance (d) is also determined with the aid of the thermometer-determinable temperature of the component and/or the sensors and with the aid of the information stored in the control and evaluation unit.

13. The system according to claim 1 , wherein:
the sensor distance (d) is in the range of 1 mm to 100 mm.

14. The system according to claim 1 , wherein:
the sensor distance (d) is in the range of 5 mm to 50 mm.

15. The system according to claim 1 , wherein:
the sensor distance (d) is in the range of 10 mm to 30 mm.

16. The system according to claim 1 , wherein:
the sensor distance (d) is in the range of 20 mm ±2 mm.

17. The system according to claim 1 , wherein:
the system is designed for the optoelectronic, inductive-electronic or capacitive-electronic determination of relative positions.

18. The system according to claim 1 , wherein:
the coefficient of thermal expansion of the dimensionally stable and aging-resistant material does not exceed the absolute value of 5×10 −6 K −1 , at least within a temperature range of 253K to 343K.

19. The system according to claim 1 , wherein:
the coefficient of thermal expansion of the dimensionally stable and aging-resistant material does not exceed the absolute value of 5×10 −6 K −1 , at least within a temperature range of 288K to 303K.

20. The system according to claim 1 , wherein:
the coefficient of thermal expansion of the dimensionally stable and aging-resistant material does not exceed the absolute value of 5×10 −6 K −1 , at least within a temperature range of 291K to 295K.

21. The system according to claim 1 , wherein:
the sensor distance (d) is defined independently of the distance between encoder elements or groups of encoder elements.

22. The system according to claim 1 , wherein:
the system is designed as a linear encoder system.

23. A method for highly precisely determining a sensor distance between a first sensor and a second sensor, the first sensor and second sensor being to sensors,
the two sensors are arranged in a fixed relative position to each other,
the two sensors being part of a system for determining relative positions by moving the two sensors commonly relative to an encoder having encoder elements, whereby the first sensor detects a first encoder element and the second sen

Assignees

• Hexagon Technology Ct Gmbh

Inventors

• Vokinger Urs
• Lippuner Heinz
• Amann Werner
• Siercks Knut

Classifications

• G01D5/34707 Primary

  Scales; Discs, e.g. fixation, fabrication, compensation · CPC title

• G01D5/34746 Primary

  Linear encoders · CPC title