Optical encoding device including an encoding disc having diffracting patterns

Patent metadata

Field	Value
Publication number	US-10247582-B2
Application number	US-201715414630-A
Country	US
Kind code	B2
Filing date	Jan 25, 2017
Priority date	Oct 21, 2016
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

An optical encoding device includes a light source module, an encoding disc, and a photodetector. The light source module emits a source beam. The encoding disc is disposed on a passing path of the source beam. The encoding disc has first diffracting patterns. The first diffracting patterns include a plurality of sets of first diffracting patterns arranged along a radial direction of the encoding disc. Each set of the first diffracting patterns includes a plurality kinds of first diffracting patterns having different pattern extending directions and different pattern periods. When the encoding disc is rotating, the first diffracting patterns in each set of first diffracting patterns enter the passing path of the source beam in sequence, to cause a diffraction and form diffracted beams having different angles. The photodetector receives the diffracted beams having the different angles.

First claim

What is claimed is:

1. An optical encoding device, comprising:
a light source module configured to emit a source beam;
an encoding disc disposed on a passing path of the source beam, wherein the encoding disc has a plurality of first diffracting patterns, and those first diffracting patterns include a plurality of sets of first diffracting patterns arranged along a radial direction of the encoding disc, each set of first diffracting patterns includes a plurality kinds of first diffracting patterns, the plurality kinds of first diffracting patterns comply with one of following conditions (a), (b), and (c):
condition (a): the plurality kinds of first diffracting patterns have different pattern extending directions when entering the passing path and different pattern periods;
condition (b): the plurality kinds of first diffracting patterns have same pattern extending directions when entering the passing path and different pattern periods;
condition (c): the plurality kinds of first diffracting patterns have different pattern extending directions when entering the passing path and same pattern periods,
wherein the pattern extending directions and the pattern periods of different sets of the first diffracting patterns are different from each other, wherein when the encoding disc is rotating, a plurality of first diffracting patterns in each set of first diffracting patterns enter the passing path of the source beam in sequence, so as to cause a diffraction and form a plurality of diffracted beams having different angles; and
a photodetector including a plurality of first light sensors to receive the plurality of diffracted beams having the different angles respectively.

2. The optical encoding device according to claim 1 , wherein the light source module is a laser emitter or a light emitting diode.

3. The optical encoding device according to claim 1 , further comprising a sensing circuit electrically connected to the photodetector, wherein the sensing circuit is configured to analyze a plurality of signals transmitted form the plurality of first light sensors, so as to obtain a rotating location of the encoding disc.

4. The optical encoding device according to claim 1 , wherein the encoding disc is a transparent encoding disc, and the source beam and the plurality of diffracted beams are on the opposite side of the encoding disc.

5. The optical encoding device according to claim 4 , further comprising a reflector disposed on the passing path of the source beam, to reflect the source beam from the light source module to the encoding disc.

6. The optical encoding device according to claim 1 , wherein the encoding disc is a non-transparent encoding disc, and the source beam and the plurality of diffracted beams are on a same side of the encoding disc.

7. The optical encoding device according to claim 6 , wherein a surface of the encoding disc is coated with a reflecting film.

8. The optical encoding device according to claim 1 , wherein a shape of a distribution area of each of the plurality of first diffracting patterns is chosen from a group consisting of square, rectangle, rhombus, circle, ellipse, triangle, and polygon.

9. The optical encoding device according to claim 1 , wherein each of the plurality of first light sensors is a photodiode or an avalanche photodiode.

10. The optical encoding device according to claim 1 , wherein the plurality of first light sensors form a sensing array module.

11. The optical encoding device according to claim 10 , wherein a way in which the plurality of first light sensors are arranged is chosen from a group consisting of a rectangle array, a trapezoid array, a fan-shaped distribution and an irregular distribution, or the plurality of first light sensors are arranged on multiple concentric reference circles, respectively.

12. The optical encoding device according to claim 1 , wherein the each of the plurality of first diffracting patterns is a diffracting grating pattern.

13. The optical encoding device according to claim 1 , further comprising at least one lenses disposed on the passing path of the source beam, to converge the source beam onto the encoding disc.

14. The optical encoding device according to claim 1 , further comprising at least one lenses disposed on the passing path of the plurality of diffracted beams, to converge the plurality of diffracted beams onto the photodetector.

15. The optical encoding device according to claim 1 , wherein the encoding disc further has a plurality of second diffracting patterns, those second diffracting patterns include at least one set of second diffracting patterns, those sets of first diffracting patterns and second diffracting patterns arranged along a radial direction of the encoding disc, and each of the second diffracting patterns includes a plurality of sub-diffracting patterns for respectively diffracting the source beam to form a plurality of diffracted beams having different angles, and the photodetector further comprises a plurality of second optical sensors for respectively receiving the plurality of diffracted beams from those sub-diffracting patterns.

16. The optical encoding device according to claim 15 , wherein the set of second diffracting patterns are disposed on a central area of those sets of first diffracting patterns in the radial direction.

17. The optical encoding device according to claim 15 , further comprising a sensing circuit electrically connected to the photodetector, wherein the sensing circuit analyzes a rotating location of the encoding disc according to a signal strength transmitted from those second optical sensors.

Assignees

• Ind Tech Res Inst

Inventors

• Chou Ming-Chieh
• Lee Chi-Hung
• Chen Ching-Chang
• Chen Yi-Cheng

Classifications

• G01D5/38

  by diffraction gratings · CPC title

• G01D5/3473 Primary

  Circular or rotary encoders · CPC title