SCALE MEASURING DEVICE, METHOD FOR GENERATING POSITION INFORMATION, AND DEVICE WITH MULTI-AXIS STAGE

• US 20140049252A1
• Filed: 08/19/2013
• Published: 02/20/2014
• Est. Priority Date: 08/20/2012
• Status: Active Grant

• Current Assignee: DMG Mori Seiki Co., Ltd. (Dmg Mori Co., Ltd.)
• Original Assignee: MORI Seiki Company Limited
• Inventors: Taniguchi, Kayoko, Maruyama, Shigeaki, Kusumi, Masaaki
• Granted Patent: US 9,970,788 B2
• Time in Patent Office: Days
• US Class Current: 324/207.21
• CPC Class Codes: G01D 5/2053 by a movable non-ferromagnetic conductive element
• CPC Class Codes: G01D 5/2455 with incremental and absolute tracks on the same encoder

Abstract

A scale device includes a scale main body having at least two incremental tracks, at least two or more incremental signal detection heads for detecting incremental signals from the incremental tracks, and an operation processing unit that generates, based upon detection outputs by the two or more incremental signal detection heads, relative positional information in a measuring direction of a measuring axis and parallel movement amount information in a direction orthogonal to the measuring direction.

Claims

1. A scale device, comprising:

a scale main body having at least two incremental tracks;

at least two or more incremental signal detection heads for detecting incremental signals from the incremental tracks; and

an operation processing unit which based upon detection outputs by the two or more incremental signal detection heads, generates relative positional information in a measuring direction of a measuring axis and parallel movement amount information in a direction orthogonal to the measuring direction.

2. The scale device according to claim 1, wherein three or more of the incremental signal detection heads are installed, and based upon detection outputs by the three or more incremental signal detection heads, the operation processing unit generates movement amount information in directions of respective X, Y and Z axes and rotation angle information around the respective axes.

3. The scale device according to claim 1, wherein the measurement principle is magnetic, having a magnetic recording medium in which at least two incremental tracks are magnetically recorded and the incremental signal detection heads are magnetic detection heads.

4. The scale device according to claim 3, wherein the magnetic detection head is a tunnel Magneto-Resistance Effect element.

5. The scale device according to claim 1, further comprising:

a support mechanism for supporting the incremental signal detection heads by a single fulcrum so as to freely swing thereon, with each of the incremental signal detection heads being operated in a manner like a pendulum.

6. The scale device according to claim 1, wherein the scale main body is provided with an absolute track on which an absolute pattern is recorded and incremental tracks formed by recording incremental signal patterns in a manner so as to be inclined relative to a measuring direction on two sides of the absolute track, as well as a single absolute pattern detection head for detecting the absolute pattern from the absolute track of the scale main body and at least two incremental signal detection heads for detecting incremental signals from the incremental tracks, and

wherein the operation processing unit generates absolute positional information based upon a detection output by the absolute pattern detection head, and also generates relative positional information in a measuring direction of a measuring axis and parallel movement amount information in a direction orthogonal to the measuring direction based upon detection outputs by the at least two incremental signal detection heads located on the two incremental tracks formed with the absolute track being sandwiched therebetween.

7. The scale device according to claim 6, wherein at least three of the incremental signal detection heads are installed, and based upon detection outputs by two incremental signal detection heads located apart from each other in the measuring direction of a measuring axis on the incremental track, the operation processing unit generates parallel movement amount information in a direction orthogonal to the measuring direction and rotation angle information in yawing direction.

8. The scale device according to claim 7, wherein the operation processing unit further calculates distances between the at least three incremental signal detection heads and the scale based upon strength of signals detected by the incremental signal detection heads, and generates parallel movement amount information in a Z-direction and rolling and pitching angle information.

9. The scale device according to claim 7, wherein the operation processing unit further comprises a correction table in which changes relative to changes in the scale-to-head distance of detection outputs by the at least three incremental signal detection heads are preliminarily recorded.

10. The scale device according to claim 3, further comprising:

measuring means for measuring change information relative to a change in a scale-to-head distance of the detection output by the at least three incremental signal detection heads, after having been installed in a measurement-subject device; and

correction data recording means for writing correction data formed based upon the change information obtained by the measuring means in the correction table.

11. The scale device according to claim 3, wherein the measurement principle is magnetic, having a magnetic recording medium in which an absolute pattern and incremental signal patterns are magnetically recorded, and the absolute pattern detection head and the incremental signal detection heads are magnetic detection heads.

12. The scale device according to claim 11, wherein the incremental tracks are formed by magnetically recording incremental signal patterns on two sides of the absolute track in a manner so as to be inclined by 45 degrees in reversed directions relative to a measuring direction.

13. The scale device according to claim 11, wherein the magnetic detection head is a tunnel Magneto-Resistance Effect element.

14. A multiaxial stage device comprising:

a scale main body having an absolute track with an absolute pattern and incremental tracks formed by incremental signal patterns placed on two sides of the absolute track in a manner so as to be inclined by 45 degrees in reversed directions relative to a measuring direction, which is placed on each of axes; and

an operation processing unit which based upon a detection output by an absolute pattern detection head for detecting the absolute pattern from the absolute track of the scale main body of each of the axes, generates absolute positional information, and by detecting incremental signals by two or more incremental signal detection heads from the incremental tracks, based upon detection outputs by the two or more incremental signal detection heads located on two incremental tracks formed with the absolute track being sandwiched therebetween, generates relative positional information in a measuring direction on a measuring axis and parallel movement amount information in a direction orthogonal to the measuring direction so that positional information is obtained, with the positional data obtained from the scale main bodies of the respective axes being mutually supplemented.

15. The multiaxial stage device according to claim 14, wherein two or more of the scale main bodies are attached to an XY stage so that positional information is obtained, with the positional data obtained from the scale main bodies of the respective axes being mutually supplemented.

16. The multiaxial stage device according to claim 14, wherein three or more of the scale main bodies are attached to an XYZ stage so that positional information is obtained, with the positional data obtained from the scale main bodies of the respective axes being mutually supplemented.

17. The multiaxial stage device according to claim 14, further comprising:

alarm generation means for generating an alarm in the case when among positional data obtained from the scale main bodies of the respective axes, a displacement other than the displacement of the corresponding measuring axis exceeds a predetermined value.

18. The multiaxial stage device according to claim 14, wherein three or more of the incremental signal detection heads are installed, and based upon detection outputs by the three or more incremental signal detection heads, the operation processing unit generates movement amount information in directions of respective X, Y and Z axes and rotation angle information around the respective axes.

19. The multiaxial stage device according to claim 14, wherein at least three or more of the incremental signal detection heads are installed, and based upon detection outputs by two incremental signal detection heads located apart from each other in the measuring direction of a measuring axis on the incremental track, the operation processing unit generates parallel movement amount information in a direction orthogonal to the measuring direction and rotation angle information in yawing direction so that positional information is obtained, with the positional data obtained from the scale main bodies of the respective axes being mutually supplemented.

20. The scale device according to claim 18, wherein the measurement principle is magnetic, having a magnetic recording medium in which an absolute track with the absolute pattern and the at least two incremental tracks are magnetically recorded and the incremental signal detection head is a magnetic detection head.

21. The multiaxial stage device according to claim 18, wherein the magnetic detection head is a tunnel Magneto-Resistance Effect element.

22. A scale device, comprising:

a scale having an incremental track on which an incremental pattern is recorded;

an incremental signal detection head for detecting the incremental pattern; and

a correction table on which a relationship between the strength of the incremental signal detected by the incremental signal detection head and a distance between the scale and the incremental signal detection head has been preliminarily recorded.

23. The scale device according to claim 22, further comprising:

a correction table for correcting a relationship between the incremental signals in association with the distance between the scale and the incremental signal detection head and a movement distance in a measuring direction.

24. The scale device according to claim 22, further comprising:

a correction table in which changes relative to changes in the scale-to-head distance of detection outputs by the at least three incremental signal detection heads are preliminarily recorded,

wherein by using the correction table, distances between the at least three incremental signal detection heads and the scale are calculated based upon strength of signals detected by the incremental signal detection heads so that parallel movement amount information in a Z-direction and rolling and pitching angle information are generated.

25. The scale device according to claim 22, wherein the measurement principle is magnetic, having a magnetic recording medium in which the incremental pattern is magnetically recorded and the incremental signal detection head is a magnetic detection head.

26. A scale device, comprising:

a scale having an incremental track on which an incremental pattern is recorded;

an incremental signal detection head for detecting the incremental pattern; and

operation means for finding a relationship between the strength of the incremental signal detected by the incremental signal detection head and a distance between the scale and the incremental signal detection head.

27. A positional-information generation method for a scale device constituted by a scale having an incremental track on which an incremental pattern is recorded and an incremental signal detection head for detecting the incremental pattern, comprising the steps of:

by using a correction table on which a relationship between the strength of the incremental signal detected by the incremental signal detection head and a distance between the scale and the incremental signal detection head has been preliminarily recorded, based upon a detection output by the incremental signal detection head, generating relative positional information in a measuring direction on a measuring axis and positional information corresponding to a distance between the scale and the incremental signal detection head.

28. The positional-information generation method according to claim 27, further comprising the step of:

by using a correction table in which changes relative to changes in the scale-to-head distance of detection outputs by the at least three incremental signal detection heads have been preliminarily recorded, calculating a distance between each of the at least three incremental signal detection heads and the scale from the strength of signals detected by the incremental signal detection heads so as to generate parallel movement amount information in a Z-direction and rolling and pitching angle information.

29. The positional-information generation method according to claim 27, wherein the measurement principle is magnetic, having a magnetic recording medium on which the incremental pattern is magnetically recorded and the incremental signal detection head is a magnetic detection head.