ABSOLUTE ENCODER

• US 20200132507A1
• Filed: 06/28/2018
• Published: 04/30/2020
• Est. Priority Date: 07/04/2017
• Status: Active Grant

• Current Assignee: Minebea Mitsumi, Inc.
• Original Assignee: Minebea Mitsumi, Inc.
• Inventors: OSADA, Yasuo
• Granted Patent: US 11,365,984 B2
• Time in Patent Office: Days
• CPC Class Codes: G01D 2205/26 Details of encoders or position sensors specially adapted to detect rotation beyond a full turn of 360°, e.g. multi-rotation
• CPC Class Codes: G01D 2205/28 The target being driven in rotation by additional gears
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence
• CPC Class Codes: G01D 5/14 influencing the magnitude of a current or voltage
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

The present invention provides an absolute encoder suitable for reduction in thickness. An absolute encoder, for determining a rotation amount of a main spindle that rotates a plurality of revolutions, includes a first drive gear configured to rotate in accordance with rotation of the main spindle; a first driven gear that engages with the first drive gear; a second drive gear configured to rotate in accordance with rotation of the first driven gear; a second driven gear that engages with the second drive gear; and an angular sensor configured to detect a rotation angle at which a second rotating body is rotated in accordance with rotation of the second driven gear.

Claims

1. An absolute encoder for determining a rotation amount of a main spindle that rotates a plurality of revolutions, the absolute encoder comprising;

a first drive gear configured to rotate in accordance with rotation of the main spindle;

a first driven gear that engages with the first drive gear;

a second drive gear configured to rotate in accordance with rotation of the first driven gear;

a second driven gear that engages with the second drive gear; and

an angular sensor configured to detect a rotation angle at which a second rotating body is rotated in accordance with rotation of the second driven gear.

2. The absolute encoder according to claim 1, further comprising another angular sensor configured to detect a rotation angle at which the main spindle is rotated.

3. The absolute encoder according to claim 1, further comprising:

a third drive gear configured to rotate in accordance with rotation of the first driven gear;

a third driven gear that engages with the third drive gear; and

a separate angular sensor configured to detect a rotation angle at which a third rotating body is rotated in accordance with rotation of the third driven gear.

4. The absolute encoder according to claim 3, further comprising an intermediate rotating body including the second drive gear and the third drive gear,

wherein each of the second drive gear and the third drive gear is a worm gear,

wherein each of the second driven gear and the third driven gear is a worm wheel, and

wherein, in a direction of an axial line of rotation of the intermediate rotating body, a direction of a reaction force applied to the intermediate rotating body due to rotation of the second drive gear is set to be opposite to a direction of a reaction force applied to the intermediate rotating body due to rotation of the third drive gear.

5. The absolute encoder according to claim 1, wherein the first drive gear is a worm gear,

wherein the first driven gear is a worm wheel, and

wherein an outer diameter of the first driven gear is set to be smaller than an outer diameter of the first drive gear.

11. The absolute encoder according to claim 2, further comprising:

a third drive gear configured to rotate in accordance with rotation of the first driven gear;

a third driven gear that engages with the third drive gear; and

a separate angular sensor configured to detect a rotation angle at which a third rotating body is rotated in accordance with rotation of the third driven gear.

12. The absolute encoder according to claim 2, wherein the first drive gear is a worm gear,

wherein the first driven gear is a worm wheel, and

wherein an outer diameter of the first driven gear is set to be smaller than an outer diameter of the first drive gear.

13. The absolute encoder according to claim 3, wherein the first drive gear is a worm gear,

wherein the first driven gear is a worm wheel, and

wherein an outer diameter of the first driven gear is set to be smaller than an outer diameter of the first drive gear.

14. The absolute encoder according to claim 4, wherein the first drive gear is a worm gear,

wherein the first driven gear is a worm wheel, and

wherein an outer diameter of the first driven gear is set to be smaller than an outer diameter of the first drive gear.

6. An absolute encoder for determining a rotation amount of a main spindle that rotates a plurality of revolutions, the absolute encoder comprising;

an intermediate rotating body configured to rotate at a first reduction ratio, in accordance with rotation of the main spindle;

a second rotating body configured to rotate at a second reduction ratio, in accordance with rotation of the intermediate rotating body; and

an angular sensor configured to detect a rotation angle at which the second rotating body is rotated, and

wherein an axial line of rotation of the main spindle is skew with respect to an axial line of rotation of the intermediate rotating body, and is set to be parallel to an axial line of rotation of the second rotating body.

7. The absolute encoder according to claim 6, further comprising another angular sensor configured to detect a rotation angle at which the main spindle is rotated.

8. The absolute encoder according to claim 6, further comprising:

a third rotating body of which an axial line of rotation is parallel to the axial line of rotation of the main spindle, the third rotating body being configured to rotate at a third reduction ratio, in accordance with rotation of the intermediate rotating body; and

a separate angular sensor configured to detect a rotation angle at which the third rotating body is rotated.

9. The absolute encoder according to claim 6, further comprising a housing including an outer wall section, the outer wall section being disposed on a side opposite the main spindle with respect to the intermediate rotating body,

wherein, in a plan view, the axial line of rotation of the intermediate rotating body is inclined at an angle in a range of from 5°

to 30°

with respect to a direction of extension of the outer wall section.

15. The absolute encoder according to claim 7, further comprising:

a third rotating body of which an axial line of rotation is parallel to the axial line of rotation of the main spindle, the third rotating body being configured to rotate at a third reduction ratio, in accordance with rotation of the intermediate rotating body; and

a separate angular sensor configured to detect a rotation angle at which the third rotating body is rotated.

16. The absolute encoder according to claim 7, further comprising a housing including an outer wall section, the outer wall section being disposed on a side opposite the main spindle with respect to the intermediate rotating body,

wherein, in a plan view, the axial line of rotation of the intermediate rotating body is inclined at an angle in a range of from 5°

to 30°

with respect to a direction of extension of the outer wall section.

17. The absolute encoder according to claim 8, further comprising a housing including an outer wall section, the outer wall section being disposed on a side opposite the main spindle with respect to the intermediate rotating body,

wherein, in a plan view, the axial line of rotation of the intermediate rotating body is inclined at an angle in a range of from 5°

to 30°

with respect to a direction of extension of the outer wall section.

10. An absolute encoder for determining a rotation amount of a main spindle that rotates a plurality of revolutions, the absolute encoder comprising;

a reduction mechanism including a worm speed-changing mechanism, the reduction mechanism being configured to rotate a magnet in accordance with rotation of the main spindle; and

an angular sensor configured to detect a rotation angle at which the magnet is rotated, in accordance with magnetic poles of the magnet,

wherein an axial line of rotation of the main spindle is parallel to an axial line of rotation of the magnet.