Optical encoder for detecting rotational and axial movement

• US 10,190,891 B1
• Filed: 07/16/2014
• Issued: 01/29/2019
• Est. Priority Date: 07/16/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Rothkopf, Fletcher R., Holenarsipur, Prashanth S., Ely, Colin M.
• Primary Examiner(s): Le, Que T
• Assistant Examiner(s): Bennett, Jennifer
• Application Number:
  US14/333,416
• Time in Patent Office: 1,658 Days
• Field of Search: 2502311, 25023113, 25023114, 25023116, 25023117, 356615, 356616, 356617, 356622, 356620, 33 1 N, 33 1 M, 33 1 L, 33 1 PT, 341 11, 341 13, 341 14
• CPC Class Codes: G01D 5/3473 Circular or rotary encoders
• CPC Class Codes: G01D 5/34746 Linear encoders
• CPC Class Codes: G01D 5/34792 with only digital scales or both digital and incremental scales
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: G01P 3/486 delivered by photo-electric detectors
• CPC Class Codes: G01P 3/50 for measuring linear speed G01P3/56 takes precedence

Abstract

Embodiments of the present disclosure provide an optical encoder for an electronic device. The optical encoder comprises an elongated shaft having an encoding pattern made up of axial markings and radial markings. The encoding pattern may be disposed around a circumference of the elongated shaft. The optical encoder also includes an optical sensor. In embodiments, the optical sensor includes an emitter and a photodiode array. The emitter causes light to shine on the encoding pattern. The encoding pattern reflects the light back to the photodiode array and the photodiode array determines movement of the shaft based on the reflected light.

Claims

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

an elongated shaft;

a crown attached to a first end of the elongated shaft;

a set of surface forms disposed on the shaft, the set of surface forms created as a byproduct of forming the shaft;

an optical sensor comprising a light emitter configured to emit light towards the set of surface forms;

a plurality of photodiodes arranged in an array and configured to receive diffusively reflected light from the set of surface forms; and

a processor operably connected to the plurality of photodiodes;

wherein;

a rotational movement of the elongated shaft changes the diffusely reflected light;

a translational movement of the elongated shaft changes the diffusely reflected light;

changes in the diffusely reflected light produce changes in an output of the plurality of photodiodes;

the processor is configured to analyze changes in the output of the plurality of photodiodes and determine a direction of rotation of the elongated shaft when the elongated shaft is rotated;

the processor is configured to analyze changes in the output of the plurality of photodiodes and determine a direction of translation of the elongated shaft when the elongated shaft is translated; and

the processor is configured to analyze changes in the output of the plurality of photodiodes and determine the direction of rotation and the direction of translation when the elongated shaft is rotated and translated.

2. The optical encoder of claim 1, wherein a portion of the optical sensor is radially aligned with respect to the elongated shaft.

3. The optical encoder of claim 1, further comprising a plurality of markings on the elongated shaft, wherein a first set of the plurality of markings comprises a light marking and wherein a second set of the plurality of markings comprises a dark marking.

4. The optical encoder of claim 3, wherein the plurality of markings alternate along the elongated shaft between a dark marking and a light marking.

5. The optical encoder of claim 1, further comprising a sealed portion disposed around the elongated shaft.

6. The optical encoder of claim 1, wherein the optical sensor is divided into quadrants.

7. The optical encoder of claim 1, further comprising a switch.

8. The optical encoder of claim 7, wherein the switch is configured to provide a mechanical feel.

9. The optical encoder of claim 1, wherein the plurality of photodiodes are arranged in at least two arrays.

10. The optical encoder of claim 3, wherein the dark marking causes diffuse reflection of the emitted light, and the light marking causes specular reflection of the emitted light.

11. The optical encoder for an electronic device of claim 1, wherein the emitted light is received at the plurality of photodiodes without passing through an intervening structure.

12. The optical encoder of claim 1, wherein:

the processor is configured to use multiple sequential samples of the output of the plurality of photodiodes to detect a speed of the rotational movement of the elongated shaft; and

the processor is configured to use the multiple sequential samples of the output of the plurality of photodiodes to detect a speed of the translational movement of the elongated shaft.

13. An electronic device comprising:

a processor;

a memory; and

an optical encoder, wherein the optical encoder comprises;

an elongated shaft having a plurality of markings formed as a byproduct of machining the elongated shaft and disposed around a circumference of the elongated shaft;

a crown attached to a first end of the elongated shaft;

a light emitter configured to emit light towards the elongated shaft; and

an array of photodiodes configured to receive diffusively reflected light from the elongated shaft;

wherein;

rotational and translational movements of the elongated shaft each produce changes in reception by the array of photodiodes of the diffusely reflected light from the plurality of markings;

an output from the array of photodiodes changes in response to the changes in reception of the diffusely reflected light; and

multiple sequential samples of the output from the array of photodiodes are compared by the processor to determine directions of the rotational and translational movements of the elongated shaft.

14. The electronic device of claim 13, wherein the light emitter is a laser diode light source.

15. The electronic device of claim 13, further comprising a sealing component disposed around the elongated shaft.

16. The electronic device of claim 15, wherein the sealing component comprises a transmissive window.

17. The electronic device of claim 16, wherein the transmissive window enables light from the light emitter to pass through and reflect off of the plurality of marking.

18. The electronic device of claim 13, further comprising a mechanical switch, wherein the mechanical switch is configured to be actuated by the elongated shaft.

19. The electronic device of claim 13, wherein the elongated shaft includes an encoding pattern comprising a plurality of colored strips helically extending along the shaft.

20. The electronic device of claim 13, wherein the emitted light that is reflected from the elongated shaft is received at the array of photodiodes without passing through an intervening structure.

21. A method for detecting a movement of a shaft contained within a housing of an electronic device, the method comprising:

causing a light source to emit light toward a circumference of the shaft, wherein;

the shaft includes encoding forms formed as a byproduct of a machining operation carried out on the shaft;

a crown is attached to a first end of the shaft; and

at least a portion of the encoding forms causes the light emitted from the light source to be diffusely reflected off of the shaft;

while the shaft undergoes the movement, receiving the diffusely reflected light at a photodiode array, wherein;

the movement of the shaft includes rotational movement of the shaft and translational movement of the shaft; and

the movement of the shaft changes the diffusely reflected light to produce a change in an output current of at least one photodiode in the photodiode array;

for the at least one photodiode in the photodiode array, comparing an output current at a first time period to an output current at a second time period; and

determining a direction of the rotational movement of the shaft and a direction of the translational movement of the shaft based on the comparison.

22. The method for detecting movement of a shaft of claim 21, wherein the emitted light that is reflected from the shaft is received at the photodiode array without passing through an intervening structure.