Encoder, motor with encoder, and servo system

Patent metadata

Field	Value
Publication number	US-9436166-B2
Application number	US-201414532007-A
Country	US
Kind code	B2
Filing date	Nov 4, 2014
Priority date	Nov 5, 2013
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

An encoder includes a plurality of slit tracks, a point light source, a first to third light-receiving arrays. The plurality of slit tracks respectively comprises a plurality of reflection slits. The point light source emits diffusion light to the plurality of slit tracks. The first light-receiving array receives light reflected by the slit track comprising an incremental pattern. The second light-receiving array receives light reflected by the slit track comprising an incremental pattern longer in pitch than other incremental patterns, and is disposed at a position on a side of a direction where the point light source is disposed, than the first light-receiving array, The third light-receiving array receives light reflected by the slit track comprising an absolute pattern, and is disposed at a position on a side of a direction where the point light source is disposed, than the first light-receiving array.

First claim

What is claimed is:

1. An encoder, comprising:
a plurality of slit tracks that respectively comprise a plurality of reflection slits arranged along a measurement direction;
means for emitting diffusion light to the plurality of slit tracks;
first means for receiving light reflected by the slit track comprising an incremental pattern;
second means for receiving light reflected by the slit track comprising an incremental pattern longer in pitch than other incremental patterns, disposed at a position on a side of a direction where the means for emitting diffusion light is disposed, than the first means; and
third means for receiving light reflected by the slit track comprising an absolute pattern, disposed at a position on a side of a direction where the means for emitting diffusion light is disposed, than the first means.

2. An encoder, comprising:
a plurality of slit tracks that respectively comprise a plurality of reflection slits arranged along a measurement direction;
a point light source configured to emit diffusion light to the plurality of slit tracks;
a first light-receiving array configured to receive light reflected by the slit track comprising an incremental pattern;
a second light-receiving array that is configured to receive light reflected by the slit track comprising an incremental pattern longer in pitch than other incremental patterns, and is disposed at a position on a side of a direction where the point light source is disposed, than the first light-receiving array; and
a third light-receiving array that is configured to receive light reflected by the slit track comprising an absolute pattern, and is disposed at a position on a side of a direction where the point light source is disposed, than the first light-receiving array.

3. The encoder according to claim 2 , wherein:
the point light source is disposed between the arrays consisting of the second light-receiving array and the third light-receiving array, and the first light-receiving array.

4. The encoder according to claim 3 , wherein:
the measurement direction is a circumferential direction with a center axis as the center; and
the second light-receiving array, the third light-receiving array, and the point light source are disposed on the center axis side than the first light-receiving array.

5. The encoder according to claim 4 , wherein:
the point light source and the first to third light-receiving arrays are disposed in the order of the first light-receiving array, the point light source, the third light-receiving array, and the second light-receiving array, toward the center axis from an outer portion in a radial direction of a circle.

6. The encoder according to claim 5 , wherein:
the third light-receiving array is configured as a light-receiving array of two tracks disposed so as to be practically symmetrical, sandwiching the point light source.

7. The encoder according to claim 4 , wherein:
the point light source and the first to third light-receiving arrays are disposed in the order of the first light-receiving array, the point light source, the second light-receiving array, and the third light-receiving array, toward the center axis from an outer portion in a radial direction of a circle.

8. The encoder according to claim 7 , wherein:
the third light-receiving array is configured as a light-receiving array of two tracks disposed so as to be practically symmetrical, sandwiching the point light source.

9. The encoder according to claim 4 , wherein:
the third light-receiving array is configured as a light-receiving array of two tracks disposed so as to be practically symmetrical, sandwiching the point light source.

10. The encoder according to claim 3 , wherein:
the third light-receiving array is configured as a light-receiving array of two tracks disposed so as to be practically symmetrical, sandwiching the point light source.

11. The encoder according to claim 2 , wherein:
the third light-receiving array is configured as a light-receiving array of two tracks disposed so as to be practically symmetrical, sandwiching the point light source.

12. The encoder according to claim 2 , wherein:
the point light source is disposed between the second light-receiving array and the third light-receiving array.

13. The encoder according to claim 12 , wherein:
the measurement direction is a circumferential direction with a center axis as the center; and
the first light-receiving array is disposed on an outer portion of a circle in a radial direction than anyone of the second light-receiving array, the third light-receiving array, and the point light source.

14. The encoder according to claim 13 , wherein:
the point light source and the first to third light-receiving arrays are disposed in the order of the first light-receiving array, the second light-receiving array, the point light source, and the third light-receiving array, toward the center axis from an outer portion in a radial direction of a circle.

15. The encoder according to claim 13 , wherein:
the point light source and the first to third light-receiving arrays are disposed in the order of the first light-receiving array, the third light-receiving array, the point light source, and the second light-receiving array, toward the center axis from an outer portion in a radial direction of a circle.

16. A motor with an encoder, comprising:
a linear motor wherein a mover moves with respect to a stator, or a rotary motor wherein a rotor rotates with respect to a stator; and
the encoder according to claim 2 configured to detect at least one of a position and a velocity of the mover or the rotor.

17. A servo system comprising:
a linear motor wherein a mover moves with respect to a stator, or a rotary motor wherein a rotor rotates with respect to a stator;
the encoder according to claim 2 configured to detect at least one of a position and a velocity of the mover or the rotor; and
a controller configured to control the linear motor or the rotary motor based on a detection result of the encoder.

Assignees

• Yaskawa Electric Corp

Inventors

• Yoshida Yasushi
• Matsutani Yasuhiro
• Yoshidomi Shiro
• Takada Hiroshi
• Arinaga Yuji
• Murokita Ikuma
• Harada Masanobu
• Kondo Hiroki

Classifications

• H02K11/22

  Optical devices · CPC title

• G01D5/36

  Forming the light into pulses · CPC title

• G01D5/34792 Primary

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

• G05B1/04 Primary

  with sensing of the position of the pointer of a measuring instrument · CPC title