Linear Actuators for Use in Electronic Devices

• US 20170070131A1
• Filed: 09/08/2016
• Published: 03/09/2017
• Est. Priority Date: 09/08/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Garver, Alyssa J., Degner, Brett W., Narajowski, David H., Harley, Jonah A.
• Granted Patent: US 10,566,888 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02K 1/34 Reciprocating, oscillating or vibrating parts of the magnetic circuit
• CPC Class Codes: H02K 33/00 Motors with reciprocating, oscillating or vibrating magnet, armature or coil system arrangements for handling mechanical energy structurally associated with motors H02K7/00, e.g. H02K7/06
• CPC Class Codes: H02K 33/16 with polarised armatures moving in alternate directions by reversal or energisation of a single coil system
• CPC Class Codes: H02K 33/18 with coil systems moving upon intermittent or reversed energisation thereof by interaction with a fixed field system, e.g. permanent magnets
• CPC Class Codes: H02K 35/00 Generators with reciprocating, oscillating or vibrating coil system, magnet, armature or other part of the magnetic circuit arrangements for handling mechanical energy structurally associated with generators H02K7/00, e.g. H02K7/06
• CPC Class Codes: H02K 35/02 with moving magnets and stationary coil systems
• CPC Class Codes: H02K 7/08 Structural association with bearings

Abstract

Embodiments described herein may take the form of an electromagnetic actuator that produces a haptic output during operation. Generally, an electromagnetic coil is wrapped around a central magnet array. A shaft passes through the central magnet array, such that the central array may move along the shaft when the proper force is applied. When a current passes through the electromagnetic coil, the coil generates a magnetic field. The coil is stationary with respect to a housing of the actuator, while the central magnet array may move along the shaft within the housing. Thus, excitation of the coil exerts a force on the central magnet array, which moves in response to that force. The direction of the current through the coil determines the direction of the magnetic field and thus the motion of the central magnet array.

Claims

1. A haptic feedback system for an electronic device, comprising:

a magnet assembly;

a first shaft operably connected to the magnet assembly;

a second shaft operably connected to the magnet assembly;

a first spring surrounding the first shaft;

a second spring surrounding the second shaft; and

an electromagnetic structure operative to exert a motive force on the magnet assembly, whereby the magnet assembly, first shaft, and second shaft may translate in response to the motive force;

wherein

the electromagnetic structure encircles at least a portion of the magnet assembly when the magnet assembly is in a rest state.

2. The haptic feedback system of claim 1, wherein the magnet assembly comprises:

a series of magnets, each of the series of magnets having a polarity opposing that of adjacent magnets in the series;

a main mass adjacent a first side of the series of magnets; and

an end mass adjacent a second side of the series of magnets, the second side opposing the first side.

3. The haptic feedback system of claim 2, wherein:

the first shaft is received in the main mass; and

the second shaft is received in the end mass.

4. The haptic feedback system of claim 3, wherein:

the first spring abuts the main mass; and

the second spring abuts the end mass.

5. The haptic feedback system of claim 3, wherein the first and second shafts are configured to move when the electromagnetic structure is energized.

6. The haptic feedback system of claim 5, further comprising:

a first bearing receiving the first shaft;

a second bearing receiving the second shaft;

a first end cap into which the first shaft extends and affixed to the first bearing; and

a second end cap into which the second shaft extends and affixed to the second bearing;

wherein

the first shaft moves relative to the first bearing and the first end cap;

the second shaft moves relative to the second bearing and the second end cap; and

the first bearing, first end cap, second bearing, and second end cap are stationary.

7. The haptic feedback system of claim 6, wherein the first end cap and second end cap are affixed to the housing.

8. The haptic feedback system of claim 1, wherein:

the first spring defines a first spring end and a second spring end; and

the first spring end and second spring end have a zero degree angular offset between them.

9. A method for providing haptic feedback, comprising:

energizing multiple coils surrounding a set of magnets;

moving the set of magnets in a first direction in response to energizing the multiple coils, thereby compressing a first spring;

moving a first shaft in the first direction;

de-energizing multiple coils;

expanding the first spring, thereby returning the set of magnets to an initial magnet position and the first shaft to an initial shaft position;

moving the set of magnets in a second direction, thereby compressing a second spring;

moving a second shaft in the second direction; and

expanding the second spring, thereby returning the set of magnets to the initial magnet position and the second shaft to a second initial shaft position.

10. The method of claim 9, wherein:

the first shaft moves in the first direction through a first bearing;

the second shaft moves in the second direction through a second bearing; and

the first shaft, first bearing, second shaft, and second bearing cooperate to constrain the set of magnet to a linear motion.

11. The method of claim 10, further comprising maintaining the first bearing and second bearing stationary with respect to a housing while the set of magnets moves in the first direction and the second direction.

12. The method of claim 9, wherein:

the operation of moving the set of magnets in the first direction comprises moving the set of magnets along a set of rails.

13. The method of claim 12, wherein the set of rails cooperates with the first and second shaft to constrain the set of magnets to a linear motion.

14. An actuator for an electronic device, comprising:

a housing;

multiple magnets;

a set of spacers, each of the spacers in the set separating two magnets of the multiple magnets;

a group of coils surrounding a portion of the multiple magnets;

a main mass affixed to a first magnet of the multiple magnets;

an end mass affixed to a second magnet of the multiple magnets;

a first shaft received within, and extending from, the main mass;

a second shaft received within, and extending from, the end mass;

a first bearing encircling the first shaft;

a second bearing encircling the second shaft;

a first end cap affixed to the housing and defining a first aperture;

a second end cap affixed to the housing and defining a second aperture;

a first spring around the first shaft and constrained by the first end cap and the main mass;

a second spring around the second shaft and constrained by the second end cap and the second mass; and

guide rails configured to constrain a motion of the multiple magnets, main mass, and end mass;

wherein

the multiple magnets, main mass, and end mass are configured to move along the guide rails.

15. The actuator of claim 14, wherein:

the first shaft extends into a first void defined by the first end cap; and

the second shaft extends into a second void defined by the second end cap.

16. The actuator of claim 14, wherein:

the guide rails encompass exterior edges of the multiple magnets; and

the guide rails pass through the main mass.

17. The actuator of claim 16, wherein the guide rails are C-shaped.

18. The actuator of claim 14, further comprising a set of stabilization magnets adjacent opposing sidewalls of the housing.

19. The actuator of claim 14, wherein the first and second springs are wound oppositely from one another.

20. The actuator of claim 19, wherein the first spring is configured to counter torque from the second spring, and vice versa.