Crown for an electronic watch

1. A wearable electronic device comprising:

a housing defining a side surface;

a transparent cover coupled to the housing;

a touchscreen display positioned below the cover;

a crown along the side surface of the housing and comprising a rotatable portion defining a sensing surface external to the housing; and

a rotation sensing system configured to sense a movement of the sensing surface as the rotatable portion of the crown is rotated.

2. The wearable electronic device of claim 1 , wherein:

the crown further comprises a non-rotatable portion positioned external to the housing; and

the rotation sensing system comprises a sensing element coupled to the non-rotatable portion of the crown.

3. The wearable electronic device of claim 1 , further comprising a force sensing system configured to detect a force input applied to the crown.

4. The wearable electronic device of claim 3 , further comprising:

a haptic actuator; and

a processing unit configured to cause the haptic actuator to produce a tactile output in response to a determination that the force input satisfies a force condition.

5. The wearable electronic device of claim 4 , wherein the haptic actuator is coupled to the non-rotatable portion of the crown.

6. The wearable electronic device of claim 1 , wherein the rotation sensing system comprises a sensing element coupled to the housing and configured to optically sense the movement of the sensing surface through an opening in the housing.

7. The wearable electronic device of claim 1 , wherein:

the crown further comprises a non-rotatable portion positioned external to the housing; and

the non-rotatable portion defines an exposed end surface of the crown.

8. An electronic watch comprising:

a housing;

a touchscreen display coupled to the housing;

a crown coupled to the housing and comprising:

a shaft member coupled to the housing and rotationally constrained relative to the housing; and

a rotatable member coupled to the shaft member and configured to rotate about the shaft member;

a rotation sensing system configured to detect a rotation of the rotatable member; and

a force sensing system configured to detect a force input applied to the crown.

9. The electronic watch of claim 8 , wherein:

the housing defines an opening; and

the shaft member extends through the opening and defines an exterior end surface of the crown.

10. The electronic watch of claim 9 , wherein the force input is applied to the exterior end surface of the crown.

11. The electronic watch of claim 8 , wherein the rotation sensing system comprises an optical sensor coupled to the shaft member and configured to detect the rotation of the rotatable member based on light reflected by the rotatable member.

12. The electronic watch of claim 11 , further comprising:

a processing unit within the housing; and

a conductive member extending through the shaft member and conductively coupling the optical sensor to the processing unit.

13. The electronic watch of claim 8 , wherein the force sensing system is configured to produce a signal that varies continuously in accordance with a magnitude of the force input.

14. The electronic watch of claim 8 , further comprising:

a haptic actuator; and

a processing unit configured to cause the haptic actuator to produce a tactile output in response to a determination that the force input satisfies a force condition.

15. A wearable electronic device comprising:

a housing;

a display at least partially within the housing;

a band coupled to the housing and configured to attach the wearable electronic device to a wearer;

a rotationally fixed crown extending from a side of the housing;

a first sensing system configured to detect a movement of a finger as the finger slides along a surface of the rotationally fixed crown; and

a second sensing system configured to detect a force resulting from an axial input applied to an end surface of the rotationally fixed crown.

16. The wearable electronic device of claim 15 , wherein the first sensing system comprises an optical sensing system positioned in the rotationally fixed crown and configured to detect the movement of the finger based at least in part on light reflected from the finger.

17. The wearable electronic device of claim 16 , further comprising:

a processing unit within the housing; and

a conductive member extending through the rotationally fixed crown and conductively coupling the optical sensing system to the processing unit.

18. The wearable electronic device of claim 15 , wherein the second sensing system comprises a force sensing system configured to produce a signal that varies continuously in accordance with a magnitude of the axial input.

19. The wearable electronic device of claim 15 , wherein the first sensing system comprises an optical sensing system positioned in the housing and configured to detect the movement of the finger based at least in part on light reflected from the finger.

20. The wearable electronic device of claim 15 , further comprising:

a haptic actuator; and

a processing unit configured to cause the haptic actuator to produce a tactile output in response to a determination that the axial input satisfies a force condition, the tactile output detectable at the end surface of the rotationally fixed crown.