Position measuring device

• US 7,274,464 B2
• Filed: 10/16/2002
• Issued: 09/25/2007
• Est. Priority Date: 10/23/2001
• Status: Active Grant

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr Johannes Heidenhain GmbH
• Inventors: Holzapfel, Wolfgang, Seyfried, Volker, Tondorf, Sebastian, Braasch, Jan
• Primary Examiner(s): Toatley, Jr.; Gregory J.
• Assistant Examiner(s): CONNOLLY, PATRICK J
• Application Number:
  US10/493,153
• Publication Number:
  US 20050018205A1
• Time in Patent Office: 1,805 Days
• Field of Search: 356/488, 356/494, 356/499, 356/521, 356/486, 356/487, 356/493, 356/498, 356/508, 250/231.13, 250/237.G
• US Class Current: 356/508
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01B 2290/15 Cat eye, i.e. reflection always parallel to incoming beam
• CPC Class Codes: G01B 9/02029 Combination with non-interferometric systems, i.e. for measuring the object

Abstract

A position measuring device for detecting the spatial position of a movable element in relation to a base body, the device including a linear measuring device that measures a distance between a movable element and a base body and an angle-measuring apparatus that measures an angle between the movable element and the base body. A light source that directs light along a beam path, a detector within the beam path and a grating within the beam path between the light source and the detector. For measuring the angle, the beam path extends between the movable element and the base body so that an intensity strip pattern is created by illuminating the grating by the light source, whose position relative to the detector is a measure of the angle.

Claims

1. A position measuring device for detecting the spatial position of a movable element in relation to a base body, comprising:

a linear measuring device that measures a distance between a movable element and a base body;

a length-adjustable support connecting said movable element with said base body;

a joint, by which said support is seated, pivotable in all directions around a center of rotation, in said base body, wherein said linear measuring device measures said linear displacement along said support;

an angle-measuring apparatus that measures a pivoting angle between said support and said base body;

a light source that directs light along a beam path;

a detector within said beam path; and

a grating within said beam path between said light source and said detector, wherein for measuring said pivoting angle said beam path extends between said movable element and said base body so that an intensity strip pattern is created by illuminating said grating by said light source, whose position relative to said detector is a measure of said pivoting angle.

2. The position measuring device in accordance with claim 1, further comprising a second joint that is arranged between said support and said movable element, by which said movable element is seated, pivotable around a second center of rotation, on said support.

3. The position measuring device in accordance with claim 1, wherein said light source is arranged in said center of rotation.

4. The position measuring device in accordance with claim 1, wherein a center of light-sensitive elements of said detector is arranged in said center of rotation.

5. The position measuring device in accordance with claim 2, wherein said light source is arranged in said center of rotation, and a center of light-sensitive elements of said detector is arranged in said second center of rotation.

6. The position measuring device in accordance with claim 1, wherein said joint is a gimbal-mounted joint.

7. The position measuring device in accordance with claim 2, wherein said joint is a gimbal-mounted joint and said second joint is a gimbal-mounted joint.

8. The position measuring device in accordance with claim 1, wherein said joint is a magnetically prestressed ball joint.

9. The position measuring device in accordance with claim 1, wherein said joint is a magnetically prestressed ball joint and said second joint is a magnetically prestressed ball joint.

10. The position measuring device in accordance with claim 1, further comprising:

a scanning unit of said linear measuring device; and

wherein said support comprises;

a first telescoping element comprising a scale attached thereto;

a second telescoping element telescopically attached to said first telescoping element, wherein said scanning unit is fastened on said second telescoping element and said scanning unit scans said scale; and

a cover for said angle-measuring apparatus.

11. The position measuring device in accordance with claim 1, wherein said linear measuring device is an interferometer.

12. The position measuring device in accordance with claim 11, wherein said light is split into a first partial beam for said angle-measuring apparatus and a second partial beam for said linear measuring device.

13. The position measuring device in accordance with claim 1, wherein said grating is a two-dimensional cross grating that generates a two-dimensional intensity pattern, whose position in relation to said detector is a measure of said angle.

14. A position measuring system comprising:

a program-controlled machine comprising;

a base element; and

a movable portion that moves relative to said base;

a position measuring device comprising;

a linear measuring device that measures a distance between a movable element that is fixed to said base element and a base body that is fixed to said base element;

a length-adjustable support connecting said movable element with said base body;

a joint, by which said support is seated, pivotable in all directions around a center of rotation, in said base body, wherein said linear measuring device measures said linear displacement along said support.

an angle-measuring apparatus that measures a pivoting angle between said movable element and said support;

a light source that directs light along a beam path;

a detector within said beam path; and

a grating within said beam path between said light source and said detector, wherein for measuring said pivoting angle said beam path extends between said movable element and said base body so that an intensity strip pattern is created by illuminating said grating by said light source, whose position relative to said detector is a measure of said pivoting angle.

15. The position measuring system in accordance with claim 14, further comprising a second joint that is arranged between said support and said movable element, by which said movable element is seated, pivotable around a second center of rotation, on said support.

16. The position measuring system in accordance with claim 14, further comprising:

a scanning unit of said linear measuring device; and

wherein said support comprises;

a first telescoping element comprising a scale attached thereto;

a second telescoping element telescopically attached to said first telescoping element, wherein said scanning unit is fastened on said second telescoping element and said scanning unit scans said scale; and

a cover for said angle-measuring apparatus.

17. The position measuring system in accordance with claim 14, wherein said linear measuring device is an interferometer.

18. The position measuring system in accordance with claim 17, wherein said light is split into a first partial beam for said angle-measuring apparatus and a second partial beam for said linear measuring device.