Absolute position determination

Patent metadata

Field	Value
Publication number	US-10082409-B2
Application number	US-201615217570-A
Country	US
Kind code	B2
Filing date	Jul 22, 2016
Priority date	Jul 24, 2015
Publication date	Sep 25, 2018
Grant date	Sep 25, 2018

Abstract

Some embodiments of the invention relate to an absolute code scale of an angle or linear position encoder, which is composed of a first absolute code sequence having a first primary code period length, which is periodically continued, and at least one second absolute code sequence having a second primary code period length, which is periodically continued. The first and the at least one second absolute code sequence are codeword-foreign in relation to one another in this case.
Along the absolute code scale, in each case one section from the first and one section from the at least one second absolute code sequence are successively arranged alternately and in this case the absolute code sequences are each shifted in relation to one another in the different sections from the same absolute code sequence along this arrangement.

First claim

What is claimed is:

1. An absolute code scale of a position encoder, comprising:
a first absolute code sequence having a first primary code period length, which code sequence is periodically continued, and
at least one second absolute code sequence having a second primary code period length, which code sequence is periodically continued,
wherein the first absolute code sequence and the at least one second absolute code sequence have different codewords in relation to one another, and
wherein alternately one section from the first absolute code sequence and one section from the at least one second absolute code sequence are successively arranged along the absolute code scale, and
wherein, in the different sections from the same absolute code sequence, the absolute code sequences are shifted differently in relation to one another along this arrangement.

2. The absolute code scale according to claim 1 , wherein the absolute code sequences are phase-shifted by a different fraction of the primary period length of the absolute code sequence.

3. The absolute code scale according to claim 1 , wherein the absolute code scale comprises a linear position encoder or a rotational encoder.

4. The absolute code scale according to claim 1 , wherein:
the first absolute code sequence and the at least one second absolute code sequence are each a binary maximum length sequence, wherein the first absolute code sequence and the at least one second absolute code sequence are each a segmentation of a single maximum sequence into at least two fragments, the fragment lengths of which do not have any common divisors.

5. The absolute code scale according to claim 1 , wherein:
adjoining, successively arranged sections of the absolute code sequences are formed having different alignments of code marks which are coding the absolute code,
wherein in each case the first absolute code sequence is formed in the form of bar-marks having a first angle in relation to a longitudinal direction of the absolute code scale and the at least one second absolute code sequence is formed in the form of bar-marks having at least one second angle, which is different from the first, in relation to the longitudinal direction of the absolute code scale,
wherein the first sections and at least second sections are assignable to the first absolute code sequence or to the at least one second absolute code sequence, on basis of an affiliation of the read code.

6. The absolute code scale according to claim 5 , wherein:
the code value is formed in a relative ratio of two distances of a first and second code mark in relation to a geometrical distance between two of the code marks.

7. The absolute code scale according to claim 5 , wherein:
the code value is formed in a relative ratio of two widths a geometrical extent of one of the code marks in relation to a geometrical distance between two of the code marks.

8. The absolute linear measurement system according to claim 7 , wherein:
the code read unit has a plurality of absolute code read regions, which are arranged harmonically in relation to a segmentation of the successively arranged sections of the absolute code scale to be read out.

9. The absolute linear measurement system according to claim 7 , wherein:
the arrangement of the sensor elements of the code read unit is at least of equal length or longer than at least one length of the longest of the sections, plus two times a unique codeword length of the absolute code sequences.

10. The absolute code scale according to claim 1 , wherein:
an absolute position along the absolute code scale is ascertainable on basis of the shift of two sections of the same absolute code sequence in relation to one another.

11. The absolute code scale according to claim 1 , wherein:
it is formed by an arrangement of code marks on a code carrier, in which arrangement a code value of one of the code marks is formed on the basis of a ratio of a first geometrical property of the code mark in relative relationship to a second geometrical property of a second code mark,
wherein the code carrier is movable in relation to a code read unit and an absolute position of the read unit in relation to the code carrier is ascertainable using the code read unit on basis of an acquisition of a part of the number of the code marks.

12. The absolute code scale according to claim 1 , wherein:
the code marks are evaluated polyvalently with respect to a plurality of their geometrical properties in relationship to each other.

13. An absolute linear measurement system having an absolute code scale according to claim 1 , and
at least one contactless code read unit having a linear, substantially coherent arrangement, which is aligned substantially longitudinally to the absolute code scale, of a plurality of sensor elements,
wherein the code read unit is designed to acquire and evaluate the absolute code scale on the basis of physical characteristics of code marks of the absolute code scale.

14. The absolute linear measurement system according to claim 13 , wherein:
the plurality of sensor elements comprises optical sensor elements.

15. The absolute linear measurement system according to claim 13 , wherein:
the physical characteristics of code marks comprise an intensity.

16. A method for absolute coding of a code scale of a linear encoder or a rotational encoder, comprising:
providing a first absolute code sequence and a second absolute code sequence, which have different codewords in relation to one another,
providing periodic repetitions of the first and the second absolute code sequences, which are each offset in the code sequence direction, and
an alternating concatenating of sections from the respective offset first and second absolute code sequences,
wherein the sections are greater than or equal to the unique codeword length of the respective absolute code sequences.

17. A method for reading out an absolute-coded code scale of a linear encoder or rotational encoder, comprising:
acquiring a part of the code scale using a linear sensor array aligned at least substantially longitudinally in relation to the code scale,
evaluating a coding in the acquired part and assigning portions of the acquired part of the absolute-coded code scale to one of at least two different absolute code sequences that have different codewords, and
determining a relative location of at least two of the portions, which portions are assigned to the same absolute code sequence, on the basis of the codings in the portions, by an offset of the portions in relation to one another, and
utilizing the offset as an absolute-coded position information of the sensor array in relation to the code scale.

18. The method according to claim 17 , wherein, further comprising:
locating of the absolute-coded position information on basis of a determining of a location of at least one code mark which forms the coding, in relation to the sensor array.

19. The method according to claim 18 , wherein the location comprises a focal point location.

20. The method according to claim 17 , wherein:
the portions from different absolute code sequences are formed using code marks which have different known alignments in relation to a direction of the code scale, and
a recognition of a transverse offset is performed from a relative location of portions having different codings in relation to one another and on the basis of the known alignments thereof.

21. The method according to claim 17 , wherein:
an

Assignees

• Hexagon Technology Ct Gmbh

Inventors

• Jordil Pascal
• Fritsch Robert

Classifications

• G01D5/26 Primary

  characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light · CPC title

• G01D5/2497

  Absolute encoders (G01D5/2454 takes precedence) · CPC title

• G01D5/34792 Primary

  with only digital scales or both digital and incremental scales · CPC title

• G01D5/3473

  Circular or rotary encoders · CPC title

• G01D5/34746

  Linear encoders · CPC title