Linear encoder

• US 8,234,792 B2
• Filed: 09/28/2010
• Issued: 08/07/2012
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Schenk, Oliver, Reith, Andreas
• Primary Examiner(s): FULTON, CHRISTOPHER W
• Application Number:
  US12/924,446
• Publication Number:
  US 20110072676A1
• Time in Patent Office: 679 Days
• Field of Search: 337/07, 337/06
• US Class Current: 33/706
• CPC Class Codes: G01D 2205/50 Grounding or electrostatically shielding a position sensor or encoder
• CPC Class Codes: G01D 5/34761 Protection devices, e.g. caps; Blowing devices
• CPC Class Codes: G01D 5/34769 Sealing means

Abstract

A linear encoder that includes a housing having: an elongated hollow profile section including a first face end and a second face end; a cap disposed on the first face end; and a seal which is disposed in sealing fashion between the hollow profile section and the cap, wherein the seal includes an electrically conductive connecting element. The linear encoder further includes a scale made of electrically nonconductive material, wherein the scale is disposed inside the housing and the scale includes a measuring graduation that is scannable by a scanning unit, which is movable in a measurement direction relative to the housing. The linear encoder includes a shunt made of electrically conductive material, wherein the shunt is mounted on the scale and extends in the measurement direction and wherein the electrically conductive connecting element is configured so as to establish an electrical connection between the shunt and at least one of the hollow profile section and the cap.

Claims

1. A linear encoder comprising:

a housing comprising;

an elongated hollow profile section comprising a first face end and a second face end;

a cap disposed on said first face end; and

a seal which is disposed in sealing fashion between said hollow profile section and said cap, wherein said seal comprises an electrically conductive connecting element;

a scale made of electrically nonconductive material, wherein said scale is disposed inside said housing and said scale comprises a measuring graduation that is scannable by a scanning unit, which is movable in a measurement direction relative to said housing;

a shunt made of electrically conductive material, wherein said shunt is mounted on said scale and extends in said measurement direction; and

wherein said electrically conductive connecting element comprises an electrically conductive elastomer and said electrically conductive connecting element is configured so as to establish an electrical connection between said shunt and at least one of said hollow profile section and said cap.

2. The linear encoder as defined by claim 1, wherein said electrically conductive connecting element is integrally formed onto said seal, and wherein said electrically conductive connecting element and said seal together comprise an electrically conductive elastomer.

3. The linear encoder as defined by claim 2, wherein said seal is embodied in plate-like fashion and rests on a face end of the hollow profile section and furthermore has at least one protrusion, which forms said electrically conductive connecting element and resiliently contacts said shunt.

4. The linear encoder as defined by claim 2, wherein said shunt is an electrically conductive layer applied to said scale.

5. The linear encoder as defined by claim 1, wherein said seal is embodied in plate-like fashion and rests on a face end of the hollow profile section and furthermore has at least one protrusion, which forms said electrically conductive connecting element and resiliently contacts said shunt.

6. The linear encoder as defined by claim 1, wherein said shunt is an electrically conductive layer applied to said scale.

7. The linear encoder as defined by claim 1, wherein said measuring graduation comprises markings of electrically conductive material, spaced apart from one another in said measurement direction, which are connected electrically conductively to one another via an electrically conductive layer that forms said shunt, and said connecting element contacts said coating.

8. The linear encoder as defined by claim 7, wherein said scale comprises a transparent material on which said markings are applied.

9. The linear encoder as defined by claim 1, wherein said scale comprises a transparent material on which said measuring graduation is applied in the form of opaque markings.

10. A linear encoder comprising:

a scanning unit;

a housing comprising;

an elongated hollow profile section comprising a first face end and a second face end;

a cap disposed on said first face end; and

a seal which is disposed in sealing fashion between said hollow profile section and said cap, wherein said seal comprises an electrically conductive connecting element;

a scanning unit disposed inside said housing and which is movable in a measurement direction relative to said housing;

a scale made of electrically nonconductive material, wherein said scale is disposed inside said housing and said scale comprises a measuring graduation that is scannable by said scanning unit;

a shunt made of electrically conductive material, wherein said shunt is mounted on said scale and extends in said measurement direction; and

wherein said electrically conductive connecting element comprises an electrically conductive elastomer and said electrically conductive connecting element is configured so as to establish an electrical connection between said shunt and at least one of said hollow profile section and said cap.

11. The linear encoder as defined by claim 10, wherein said electrically conductive connecting element is integrally formed onto said seal, and wherein said electrically conductive connecting element and said seal together comprise an electrically conductive elastomer.

12. The linear encoder as defined by claim 11, wherein said seal is embodied in plate-like fashion and rests on a face end of the hollow profile section and furthermore has at least one protrusion, which forms said electrically conductive connecting element and resiliently contacts said shunt.

13. The linear encoder as defined by claim 11, wherein said shunt is an electrically conductive layer applied to said scale.

14. The linear encoder as defined by claim 10, wherein said seal is embodied in plate-like fashion and rests on a face end of the hollow profile section and furthermore has at least one protrusion, which forms said electrically conductive connecting element and resiliently contacts said shunt.

15. The linear encoder as defined by claim 10, wherein said shunt is an electrically conductive layer applied to said scale.

16. The linear encoder as defined by claim 10, wherein said measuring graduation comprises markings of electrically conductive material, spaced apart from one another in said measurement direction, which are connected electrically conductively to one another via an electrically conductive layer that forms said shunt, and said connecting element contacts said coating.

17. The linear encoder as defined by claim 16, wherein said scale comprises a transparent material on which said markings are applied.

18. The linear encoder as defined by claim 10, wherein said scale comprises a transparent material on which said measuring graduation is applied in the form of opaque markings.

19. The linear encoder as defined by claim 10, wherein the scanning unit is secured to an attachment which extends through said seal.