Force Sensing of Inputs Through Strain Analysis

• US 20160041672A1
• Filed: 03/15/2013
• Published: 02/11/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hoen, Storrs T., Christophy, Miguel C., Teil, Romain A., Filiz, Sinan, Babiarz, Kristina A., Katiyar, Vivek
• Granted Patent: US 9,952,703 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04144 using an array of force sensing means position sensing using the local deformation of sensor cells G06F3/0447
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

An electronic device having a force sensor that determines a measure of applied force from a user contacting a cover glass element through the use of strain probes.

Claims

1. An electronic device, comprising

a frame at least partially enclosing an interior of the electronic device, the frame having an open end;

a cover glass covering the open end of the frame, the cover glass movably connected to the frame to allow movement of the cover glass in response to one or more forces applied to an external surface of the cover glass;

a plurality of strain probes arranged to output a plurality of strain signals responsive to the force applied to the cover glass; and

a force processing module configured to at least calculate an amount of force applied to the cover glass based on the plurality of stain signals.

2. The electronic device of claim 1, further comprising

an array of sensing elements arranged to output a plurality of sense signals that indicate a location on the cover glass of one or more touches;

wherein the force processing module is further configured to calculate a force applied to the cover glass at each touch location based on the strain signals and the sense signals.

3. The electronic device of claim 2, wherein the force processing module calculates the force applied at two or more touch locations by first calculating a centroid of a total force applied and then calculating the force applied at each touch location based on the centroid of the total force and the location of each touch as indicated by the sense signals.

4. The electronic device of claim 1, further comprising

a cover glass support member fixedly connected to the frame and in supportive contact with the cover, the plurality of strain probes being associated with the support member.

5. The electronic device of claim 4, wherein the cover glass support member comprises

an upper support comprising an upper surface in supportive contact with the cover glass;

a lower support fixedly connected to the frame; and

a bending beam disposed between the upper and lower support, the plurality of strain probes disposed on the bending beam;

wherein the movement of the cover glass causes the upper support to move towards the lower support thereby deforming the bending beam, the deformation of the bending beam causing a corresponding change in the output from the strain probes.

6. The electronic device of claim 5, wherein

the upper support includes a plurality of pedestals disposed on a lower surface of the upper support, the plurality of pedestals concentrating the force imparted from the cover glass onto discrete areas along the bending beam.

7. The electronic device of claim 6, wherein the cover glass support member further comprises a plurality of flexures, each flexure comprising

an upper strain probe disposed on the upper surface of the bending beam;

and

a lower strain probe disposed on the lower surface the bending beam.

8. The electronic device of claim 7, wherein each pedestal has a first flexure adjacent to a first side of the pedestal and a second flexure adjacent to a second side of the pedestal.

9. The electronic device of claim 8, wherein each pedestal is associated with a wheatstone bridge that interconnects the upper and lower strain probes of the first flexure and the upper and lower strain probes of the second flexure.

10. The electronic device of claim 5, wherein

the lower support includes a stop surface that prevents further movement of the cover glass when the lower surface of the bending beam contacts the stop surface.

11. The electronic device of claim 4, wherein the cover glass support member comprises

at least one bending beam that is in supportive contact with the cover glass;

a plurality of clips, wherein each clip attaches a bending beam end to an interior of the frame, each clip having one of the plurality of strain probes disposed thereon;

wherein the movement of the cover glass causes each of the clips to rotate, thereby causing a corresponding change in the output from the strain probes.

12. The electronic device of claim 4, wherein the cover glass further comprises

an opaque region located along a perimeter of the cover glass;

wherein the plurality of strain probes are located on an interior surface of the cover glass within the opaque region.

13. The electronic device of claim 12, further comprising

a compressible layer connected on a first side to the interior surface of the cover glass within the opaque region and connected on a second side fixed datum within the interior of the electronic device.

14. The electronic device of claim, 12 further comprising

an elastomeric border connected to the frame and disposed between the cover glass and the frame;

and

a compressible layer connected on a first side to the interior surface of the cover glass within the opaque region and connected on a second side to the elastomeric border.

15. A support member for a cover glass component of an electronic device, comprising

an upper support comprising an upper surface adapted to be in supportive contact with the cover glass;

a lower support adapted to be fixedly connected to a frame of the electronic device; and

a bending beam disposed between the upper and lower support; and

a plurality of strain probes disposed on the bending beam;

wherein a movement of the cover glass causes the upper support to move towards the lower support thereby deforming the bending beam, the deformation of the bending beam causing a corresponding change in the output from the strain probes.

16. The support member of claim 15, wherein

the upper support includes a plurality of pedestals disposed on a lower surface of the upper support, the plurality of pedestals concentrating a force imparted from the cover glass onto discrete areas along the bending beam.

17. The support member of claim 16, further comprising a plurality of flexures, each flexure comprising

an upper strain probe disposed on the upper surface of the bending beam;

and

a lower strain probe disposed on the lower surface the bending beam.

18. The support member of claim 17, wherein each pedestal has a first flexure adjacent to a first side of the pedestal and a second flexure adjacent to a second side of the pedestal.

19. The support member of claim 18, wherein each pedestal is associated with a wheatstone bridge that interconnects the upper and lower strain probes of the first flexure and the upper and lower strain probes of the second flexure.

20. The support member of claim 15, wherein

the lower support includes a stop surface that prevents further movement of the cover glass when the lower surface of the bending beam contacts the stop surface.

21. A support member for a cover glass component of an electronic device, comprising

at least one bending beam adapted to be in supportive contact with the cover glass;

a plurality of clips, wherein each clip is adapted to attach a bending beam end to an interior of the frame, each clip having one of the plurality of strain probes disposed thereon;

wherein a movement of the cover glass causes each of the clips to rotate, thereby causing a corresponding change in the output from the strain probes.

22. A cover glass component of an electronic device, comprising

an opaque region located along a perimeter of the cover glass;

a plurality of strain probes located on an interior surface of the cover glass within the opaque region.

23. The cover glass component of claim 22, further comprising

a compressible layer connected on a first side to the interior surface of the cover glass within the opaque region and connected on a second side fixed datum within the interior of the electronic device.

24. The cover glass component of claim 23 further comprising

an elastomeric border connected to the frame and disposed between the cover glass and the frame;

and

a compressible layer connected on a first side to the interior surface of the cover glass within the opaque region and connected on a second side to the elastomeric border.