Position-measuring device having four scanning units and two measuring graduations

Patent metadata

Field	Value
Publication number	US-11940304-B2
Application number	US-202117405065-A
Country	US
Kind code	B2
Filing date	Aug 18, 2021
Priority date	Aug 27, 2020
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

A position-measuring device includes a scale having first and second measuring graduations, which each include graduation structures that respectively extend parallel to first and second directions. A first scanning unit is associated with the first measuring graduation, and second and third scanning units are associated with the second measuring graduation. A fourth scanning unit is associated with the first or second measuring graduation. In the former case, a first straight connecting line running through scanning locations of the first and fourth scanning units and a second straight connecting line running through scanning locations of the second and third scanning units are parallel or form a predetermined angle therebetween that is not equal to a sum of the angles of the first and second directions. In the latter case, the scanning locations of the second, third and fourth scanning units do not lie on a common straight connecting line.

First claim

What is claimed is:

1. A position-measuring device, comprising:
a scale having a first measuring graduation and a second measuring graduation, the first measuring graduation including a series of graduation structures which each extend parallel to a first direction, the second measuring graduation including a series of graduation structures which each extend parallel to a second direction, the first and second directions extending at a respective angle different from 0° with respect to a longitudinal axis of the scale;
a first scanning unit associated with the first measuring graduation for scanning the first measuring graduation;
a second scanning unit associated with the second measuring graduation for scanning the second measuring graduation;
a third scanning unit associated with the second measuring graduation for scanning the second measuring graduation; and
a fourth scanning unit associated with the first measuring graduation for scanning the first measuring graduation, and
wherein a first straight connecting line running through centers of the first and fourth scanning units and a second straight connecting line running through centers of the second and third scanning units form a predetermined angle therebetween, the predetermined angle being not equal to a sum of the angle of the first direction and the angle of the second direction.

2. The position-measuring device as recited in claim 1 , wherein the position-measuring device has a scanning unit carrier disposed so as to be movable relative to the scale, the scanning unit carrier being configured to carry each of the scanning units.

3. The position-measuring device as recited in claim 2 , wherein the first and second measuring graduations and each of the scanning units are arranged and adapted such that a position of the scanning unit carrier relative to the scale can be determined in a first measurement direction and in two other degrees of freedom.

4. The position-measuring device as recited in claim 1 , wherein the angle of the first direction and the angle of the second direction are each in a range of 15° to 165°.

5. The position-measuring device as recited in claim 4 , wherein the angle of the first direction and the angle of the second direction are each in a range of 30° to 150°.

6. The position-measuring device as recited in claim 1 , wherein the angle of the first direction and the angle of the second direction are equal in magnitude.

7. The position-measuring device as recited in claim 6 , wherein the angle of the first direction and the angle of the second direction are each 45°.

8. The position-measuring device as recited in claim 1 , wherein the angle of the first direction is 90° and the angle of the second direction is 45°.

9. The position-measuring device as recited in claim 1 , wherein the first straight connecting line or the second straight connecting line is parallel to the longitudinal axis of the scale.

10. The position-measuring device as recited in claim 1 , wherein the predetermined angle differs by more than ±5°, ±10° or ±15° from the sum of the angle of the first direction and the angle of the second direction.

11. The position-measuring device as recited in claim 1 , wherein a perpendicular distance of the center of the fourth scanning unit from the second straight connecting line is greater than 2 mm, 1 mm, or 0.1 mm.

12. The position-measuring device as recited in claim 1 , wherein the graduation structures of the first measuring graduation and the graduation structures of the second measuring graduation are respectively arranged periodically along a first measurement direction.

13. The position-measuring device as recited in claim 1 , wherein the first and second measuring graduations are each absolute graduations.

14. The position-measuring device as recited in claim 1 , wherein the first and second measuring graduations are each optically scannable.

15. The position-measuring device as recited in claim 1 , wherein the predetermined angle is not equal to zero.

16. The position-measuring device as recited in claim 15 , wherein the predetermined angle is 15°.

17. The position-measuring device as recited in claim 1 , wherein the scanning units each include a scanning location that is a reference point for a position measurement and is located at the center of the respective scanning unit.

Assignees

• Heidenhain Gmbh Dr Johannes

Inventors

• Mitterleitner Josef
• Becker Thomas

Classifications

• G01D5/24438 Primary

  Special design of the sensing element or scale · CPC title

• G01D5/34707

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

• G01D5/34715

  Scale reading or illumination devices · CPC title

• G01D5/34746

  Linear encoders · CPC title

• G01D5/3473

  Circular or rotary encoders · CPC title