Moving-coil haptic actuator for electronic devices

• US 10,032,550 B1
• Filed: 03/30/2017
• Issued: 07/24/2018
• Est. Priority Date: 03/30/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhang, Zhipeng, Koch, Richard H.
• Primary Examiner(s): Haughton, Anthony
• Application Number:
  US15/474,638
• Time in Patent Office: 481 Days
• Field of Search: 36167955, 36167956, 36167921-6793
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user
• CPC Class Codes: H01F 2007/185 with armature position measurement
• CPC Class Codes: H01F 7/064 Circuit arrangements for actuating electromagnets circuit arrangements for obtaining special operating characteristics H01F7/18; driving circuits for electromagnets making use of a switching regulator H01H47/325
• CPC Class Codes: H01F 7/066 Electromagnets with movable winding
• CPC Class Codes: H01F 7/1646 Armatures or stationary parts of magnetic circuit having permanent magnet

Abstract

A haptic actuator features magnets coupled to an enclosure and a movable mass with a conduction loop coupled to the enclosure via one or more movement elastic members. One or more conduction elastic members may be used to transmit signals to the conduction loop to cause the movable mass to move bilinearly relative to the enclosure and the magnets. The magnets may consist of a Halbach array to direct magnetic flux toward the conduction loop and away from other device components. Ferrofluid may be included between one or more of the magnets and the conduction loop to act as a damper in the system to improve haptic feedback. Closed loop control, such as back EMF, capacitive sensing, and magnetic sensing, may be included to improve system response.

Claims

1. An electronic device comprising:

a device casing;

a display coupled to the device casing;

an actuator coupled to the device casing and for providing haptic feedback through the device casing, the actuator comprising;

an enclosure that forms an interior volume;

a magnet attached to the enclosure, the magnet configured to generate a first magnetic field in the interior volume;

a movable mass disposed in the interior volume, the movable mass configured to oscillate within the interior volume along a longitudinal axis of the enclosure;

a conduction loop affixed to the movable mass and operative to generate a second magnetic field in response to an electromagnetic signal;

a movement elastic member disposed between the movable mass and the enclosure and configured to exert a force on the movable mass, the force varying with a position of the movable mass; and

a conduction elastic member coupled to the enclosure and the conduction loop, the conduction elastic member configured to convey the electromagnetic signal; and

a controller coupled to the conduction loop by the conduction elastic member and configured to initiate the electromagnetic signal to the conduction loop.

2. The electronic device of claim 1, wherein:

the magnet is a first magnet;

the movement elastic member is a first movement elastic member;

the conduction elastic member is a first conduction elastic member; and

the actuator further comprises;

a second magnet attached to the enclosure, the movable mass located between the first magnet and the second magnet, the second magnet configured to generate a third magnetic field in the interior volume;

a second conduction elastic member coupled to the enclosure and the conduction loop;

a first contact attached to the enclosure and the first conduction elastic member, the first contact configured to constrain an end of the first conduction elastic member;

a second contact attached to the enclosure and the second conduction elastic member, the second contact configured to constrain an end of the second conduction elastic member;

a second movement elastic member disposed between the movable mass and the enclosure;

further wherein;

the first movement elastic member is a first flexure spring connected to a first connection location of the movable mass, the first connection location offset from the longitudinal axis in a first direction;

the second movement elastic member is a second flexure spring connected to a second connection location of the movable mass, the second connection location offset from the longitudinal axis in a second direction, the second direction different from the first direction;

the first conduction elastic member is a first beehive spring connected to a third connection location of the movable mass, the third connection location offset from the longitudinal axis;

the second conduction elastic member is a second beehive spring connected to a fourth connection location of the movable mass, the fourth connection location offset from the longitudinal axis;

the conduction loop comprises two rounded rectangular coils; and

the first and second conduction elastic members expand and contract as the movable mass moves.

3. The electronic device of claim 1, wherein the magnet comprises a Halbach array.

4. The electronic device of claim 1, wherein the movable mass comprises a first portion disposed within a second portion, the first portion thinner than a second portion.

5. The electronic device of claim 1, wherein the movement elastic member has a spring force between 0.5 and 3 N/mm.

6. The electronic device of claim 5, wherein the conduction elastic member has a spring force between 0.001-0.01 N/mm.

7. The electronic device of claim 1, wherein the actuator further comprises a ferrofluid disposed between the first magnet and the movable mass.

8. An actuator for providing haptic feedback in an electronic device, the actuator comprising:

an enclosure defining a first side and a second side opposite the first side;

a first magnet coupled to the first side of the enclosure;

a second magnet coupled to the second side of the enclosure;

a movable mass disposed between the first and second magnets;

a conduction loop connected to the movable mass;

a first movement elastic member attached to the enclosure and to a first connection location of the movable mass;

a second movement elastic member attached to the enclosure and to a second connection location of the movable mass; and

a conduction elastic member physically coupled to the enclosure and to the movable mass, the conduction elastic member electrically coupled to the conduction loop.

9. The actuator of claim 8, wherein the first and second movement elastic members comprise at least one of a flexure spring, a leaf spring, or a coil spring.

10. The actuator of claim 8, wherein a reaction force of the movement elastic member is between 100 and 1000 times greater than a spring force of the conduction elastic member.

11. The actuator of claim 8, wherein a density of the movable mass is greater than 15 grams per cubic centimeter.

12. The actuator of claim 8, wherein:

the conduction elastic member is a first conduction elastic member; and

the actuator further comprises;

a second conduction elastic member coupled to the enclosure and the movable mass;

wherein

the second conduction elastic member is electrically coupled to the conduction loop.

13. The actuator of claim 12, wherein:

the enclosure has a longitudinal axis;

the first connection location is offset from the longitudinal axis in a first direction; and

the second connection location is offset from the longitudinal axis in a second direction, the second direction different from the first direction.

14. The actuator of claim 13, wherein:

the first conduction elastic member is connected to a third connection location of the movable mass, the third connection location offset from the longitudinal axis in a third direction, the third direction different from the first direction; and

the second conduction elastic member is connected to a fourth connection location of the movable mass, the fourth connection location offset from the longitudinal axis in a fourth direction, the fourth direction different from the second direction.

15. The actuator of claim 8, wherein the conduction elastic member is one of a flexure spring, a leaf spring, or a coil spring.

16. A method for operating an actuator to provide haptic output to an electronic device, the method comprising:

transmitting a drive signal to a conduction loop of the actuator, thereby causing the conduction loop and a movable body within the actuator to oscillate;

receiving, at a controller, feedback data indicating a position of the movable body within an enclosure of the actuator;

generating, by the controller and based on the feedback data, a signal for providing a haptic output via the actuator;

transmitting the signal to the conduction loop;

receiving second feedback data indicating a second position of the movable body; and

verifying, with the second feedback data, that the haptic output matches a desired haptic output.

17. The method of claim 16, wherein verifying that the haptic output matches the desired haptic output using the second feedback data comprises comparing at least one of a determined position, a determined velocity, or a determined acceleration with one or more expected values.

18. The method of claim 16, wherein the drive signal generates, by the conduction loop, a magnetic field that interacts with one or more additional magnetic fields, thereby causing the movable body within the actuator to oscillate.

19. The method of claim 16, wherein the second position of the movable body indicates unwanted motion of the movable body.

20. The method of claim 19, further comprising:

generating a corrective signal to mitigate the unwanted motion of the movable body; and

transmitting the signal to the conduction loop.