Optical Encoder Including Diffuser Members

• US 20160069713A1
• Filed: 09/01/2015
• Published: 03/10/2016
• Est. Priority Date: 09/09/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Holenarsipur, Prashanth S., Ruh, Richard
• Granted Patent: US 10,145,712 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/342 the sensed object being the obturating part
• CPC Class Codes: G01D 5/34715 Scale reading or illumination devices
• CPC Class Codes: G01D 5/3473 Circular or rotary encoders
• CPC Class Codes: G01D 5/34738 Axles; Driving or coupling means
• CPC Class Codes: G01D 5/35303 using a reference fibre, e.g. interferometric devices

Abstract

An optical encoder having diffuser members, and methods for detecting the rotational movement of the cylinder of the optical encoder are disclosed. The optical encoder may include a rotatable cylinder configured to reflect light. The rotatable cylinder may include an encoding pattern of alternating reflective stripes having distinct light-reflective properties. The optical encoder may also include a light source positioned adjacent the rotatable cylinder, and an array of optical sensors positioned adjacent the rotatable cylinder. The array of optical sensors may receive the reflected light from the rotatable cylinder. The optical encoder may include a diffuser member positioned on the rotatable cylinder, the light source, and the array of optical sensors.

Claims

1. An electronic device comprising:

a housing;

a crown coupled to the housing and configured to receive rotational input; and

an optical encoder positioned within the housing and comprising;

a rotatable cylinder in communication with the crown;

an encoding pattern formed on an outer surface of the rotatable cylinder, the encoding pattern comprising;

a group of light-reflective markings; and

a group of non-reflective markings interspersed with the group of light-reflective markings;

a light source positioned adjacent the rotatable cylinder and configured to provide a light beam to the outer surface of the rotatable cylinder; and

an array of optical sensors positioned adjacent the rotatable cylinder, the array of optical sensors configured to receive the light beam reflected from the rotatable cylinder,

wherein the light beam provided by the light source is widened in an axial direction along a length of the rotatable cylinder prior to being received by the array of optical sensors.

2. The electronic device of claim 1, wherein the optical encoder comprises a diffuser member configured to axially diffuse at least one of:

the light beam provided by the light source before being reflected, or

the light beam reflected by the rotatable cylinder.

3. The electronic device of claim 2, wherein the diffuser member is positioned on the rotatable cylinder and comprises:

at least one set of diffuser lenses positioned on the outer surface of the rotatable cylinder.

4. The electronic device of claim 3, wherein the at least one set of diffuser lenses is disposed along an entire length of the rotatable cylinder.

5. The electronic device of claim 3, wherein each of the at least one set of diffuser lenses comprises a concave lens.

6. The electronic device of claim 3, wherein each diffuser lens of the at least one set of diffuser lenses is positioned adjacent one another to form a scalloped pattern of diffuser lenses.

7. The electronic device of claim 3, wherein the at least one set of diffuser lenses is separated by a transitional portion of the rotatable cylinder, the transitional portion configured to diffuse the light beam.

8. The electronic device of claim 3, wherein the at least one set of diffuser lenses is disposed over a distinct light-reflective marking of the group of light-reflective markings.

9. The electronic device of claim 1, wherein the optical encoder comprises a wall member positioned between the light source and the array of optical sensors, the wall member configured to prevent at least one of:

the light beam from the light source from being directly exposed to the array of optical sensors, or

the light beam reflected from the rotatable cylinder from being reflected toward the light source.

10. An optical encoder for an electronic device, the optical encoder comprising:

a rotatable cylinder configured to reflect light, the rotatable cylinder comprising an encoding pattern of alternating reflective stripes having distinct light-reflective properties;

a light source positioned adjacent the rotatable cylinder;

an array of optical sensors positioned adjacent the rotatable cylinder, the array of optical sensors configured to receive reflected light from the rotatable cylinder; and

a diffuser member positioned on at least one of;

the rotatable cylinder;

the light source;

or

the array of optical sensors.

11. The optical encoder of claim 10, wherein the diffuser member is positioned on the light source and comprises a diffuser window covering at least a portion of the light source.

12. The optical encoder of claim 11, wherein the diffuser window is positioned between the light source and the rotatable cylinder.

13. The optical encoder of claim 11, wherein a light beam provided by the light source passes through the diffuser window to the rotatable cylinder.

14. The optical encoder of claim 10, wherein the diffuser member is positioned on the array of optical sensors and comprises a diffuser sheet disposed over at least a portion of the array of optical sensors.

15. The optical encoder of claim 14, wherein the reflected light from the rotatable cylinder is configured to pass through the diffuser sheet to the array of optical sensors.

16. The optical encoder of claim 14, wherein the diffuser sheet covers at least a portion of a surface of the array of optical sensors, the surface configured to receive the reflected light from the rotatable cylinder.

17. The optical encoder of claim 10, wherein the encoding pattern of alternating reflective stripes comprises:

a group of light colored-stripes reflecting light in a specular manner; and

a group of dark colored-stripes reflecting light in a diffusive manner.

18. A method of detecting rotational movement of a rotatable cylinder of an optical encoder, the method comprising:

emitting an emitted light beam, using a light source, toward the rotatable cylinder;

reflecting the emitted light beam off the rotatable cylinder to form a reflected light beam;

receiving the reflected light beam at an array of optical sensors; and

prior to receiving of the reflected light beam, axially diffusing at least one of the emitted light beam, or the reflected light beam using a diffuser member; and

estimating an amount of rotation of the rotatable cylinder based on the reflected light beam that is received at the array of optical sensors.

19. The method of claim 18, wherein estimating the amount of rotation of the rotatable cylinder comprises:

determining a first electrical output of each optical sensor of the array of optical sensors at a first time;

receiving rotational movement of the rotatable cylinder;

determining a second electrical output of each optical sensor of the array of optical sensors at a second time subsequent to the received rotational movement of the rotatable cylinder; and

computing the amount of rotation using the first electrical output and the second electrical output.

20. The method of claim 18, wherein axially diffusing the emitted light beam comprises passing the emitted light beam through a diffuser window covering at least a portion of the light source to spread the emitted light beam in an axial direction.

21. The method of claim 18, wherein axially diffusing the emitted light beam comprises passing the emitted light beam through a plurality of diffuser lenses disposed around an outer surface of the rotatable cylinder to spread the reflected light beam in the axial direction.

22. The method of claim 18, wherein axially diffusing the reflected light beam comprises passing the reflected light beam through a diffuser sheet disposed over at least a portion of the array of optical sensors to spread the reflected light beam in an axial direction.