Geared haptic feedback element
A thin haptic feedback element suitable to provide a perceivable single pulse haptic feedback including an electromagnetic coil, a permanent magnet or other magnetic field source rotatably coupled to an eccentric mass through a torque-increasing drive train. The haptic feedback element may rapidly accelerate and decelerate the eccentric mass to produce a perceivable haptic feedback.
1. A haptic feedback element comprising:
an electromagnetic coil having a core;
a magnetic field source rotatable about a first axis, the magnetic field source positioned proximate the core;
a first gear fixedly coupled to the magnetic field source;
a second gear rotatably coupled to the first gear, the second gear rotatable about a second axis; and
a mass element fixedly coupled to the second gear positioned eccentrically to the second axis; wherein
a first angular displacement of the first gear causes a second angular displacement in the second gear.
2. The haptic feedback element of claim 1 , wherein the first angular displacement is greater than one but less than ten times the second angular displacement.
3. The haptic feedback element of claim 1 , wherein the first angular displacement is ten times or greater the second angular displacement.
4. The haptic feedback element of claim 1 , wherein the electromagnetic coil operates in at least an operation mode and a brake mode.
5. The haptic feedback element of claim 4 , wherein the operation mode comprises an alternating a magnetic field through the core.
6. The haptic feedback element of claim 4 , wherein the brake mode comprises one of fixing a magnetic field through the electromagnetic coil, reversing a magnetic field through the electromagnetic coil, and alternating a magnetic field within the electromagnetic coil.
7. The haptic feedback element of claim 1 , wherein the magnetic field source comprises a permanent magnet.
8. The haptic feedback element of claim 1 , further comprising a third gear that rotatably couples the first gear to the second gear.
9. The haptic feedback element of claim 1 , wherein the eccentric mass is metal.
10. A method of providing haptic feedback comprising:
receiving a request for haptic feedback;
providing current of a first polarity to an electromagnetic coil magnetically proximate a rotatable magnetic field source;
providing current of a second polarity to the electromagnetic coil; and
applying a braking current to the electromagnetic coil that causes an eccentric mass rotatably coupled to the rotatable magnetic field source to decelerate.
11. The method of claim 10 , wherein the operations of providing a current of a first polarity and providing a current of a second polarity repeat a selected number of times prior to the operation of applying a braking current.
12. The method of claim 11 , wherein the selected number of repetitions is determined based on an angle of rotation of the eccentric mass.
13. The method of claim 12 , wherein the angle of rotation of the eccentric mass is one tenth of the angle of rotation of rotatable magnetic field source.
14. The method of claim 10 , wherein the rotatable coupling between the rotatable magnetic field source and the eccentric mass comprises at least a first gear.
15. The method of claim 12 , wherein the angle of rotation of the eccentric mass is determined at least in part by a magnetic field sensor.
16. The method of claim 12 , wherein the angle of rotation of the eccentric mass is greater than one tenth of the angle of rotation of rotatable magnetic field source.
17. A haptic feedback element comprising:
a single-phase stepping motor with a drive axis;
a first gear fixedly coupled to the drive axis;
a second gear rotatably coupled to the first gear, the second gear rotatable about an axis of rotation;
a mass element fixedly coupled to the second gear positioned eccentrically to axis of rotation; and
a commutator configured to operate the single-phase stepping motor synchronously.
18. The haptic feedback element of claim 17 , wherein a first angular displacement of the first gear causes a second angular displacement in the second gear.
19. The haptic feedback element of claim 18 , wherein the first angular displacement is greater than one but less than ten times the second angular displacement.
20. The haptic feedback element of claim 17 , wherein a first diameter of the first gear is less than a second diameter of the second gear.