Force sensing of inputs through strain analysis

• US 9,952,703 B2
• Filed: 03/15/2013
• Issued: 04/24/2018
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hoen, Storrs T., Babiarz, Kristina A., Christophy, Miguel C., Teil, Romain A., Filiz, Sinan, Katiyar, Vivek
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US14/776,592
• Publication Number:
  US 20160041672A1
• Time in Patent Office: 1,866 Days
• 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 has a force sensor that determines a measure of applied force from a user contacting a cover glass of the device. In one embodiment, a frame at least partially encloses an interior of the electronic device and has an open end. A cover glass covers the open end of the frame and is 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 is positioned under the cover glass, between the cover glass and the frame, and is arranged to output a plurality of strain signals responsive to the one or more forces applied to the cover glass. A force processing module is configured to at least calculate an amount of force applied to the cover glass based on the plurality of stain signals.

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 positioned under the cover glass, between the cover glass and the frame, and arranged to output a plurality of strain signals responsive to the one or more forces 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 an amount of 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 amount of force applied at two or more touch locations by first calculating a centroid of a total amount of force applied and then calculating the amount of force applied at each touch location based on the centroid of the total amount of 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 glass, 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, between pedestals, that prevents further movement of the cover glass when a 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 border 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 border 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 border 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 border region and connected on a second side to the elastomeric border.

15. An electronic device, comprising:

a cover glass coupled to a frame of the electronic device;

a cover glass support member comprising;

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

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

a set of strain probes disposed between the upper and lower support;

wherein;

a movement of the cover glass causes the upper support to move towards the lower support thereby causing an associated change in an output from the set of strain probes.

16. The electronic device of claim 15, further comprising a bending beam, the set of strain probes disposed on the bending beam.

17. The electronic device of claim 16, wherein:

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

18. The electronic device of claim 15, further comprising:

a mask disposed on an interior surface of the cover glass, the mask defining an opaque border region along a perimeter of the cover glass, the set of strain probes positioned on the interior surface of the cover glass within the opaque border region.

19. The electronic device of claim 18, further comprising:

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

20. An electronic device, comprising:

a frame at least partially enclosing an interior of the electronic device;

a cover glass moveably connected to the frame;

a mask disposed on an interior surface of the cover glass, the mask defining an opaque border region along a perimeter of the cover glass; and

a set of strain probes positioned under the cover glass within the opaque border region.

21. The electronic device of claim 20, wherein:

the set of strain probes is configured to output a set of signals associated with a movement of the cover glass.

22. The electronic device of claim 20, further comprising:

at least one bending beam in supportive contact with the cover glass, wherein each bending beam has an orientation following the perimeter of the cover glass and has a first end and a second end attached to one edge of an interior of the frame; and

a set of clips, wherein each clip attaches the first end or the second end of a bending beam to the interior of the frame, each clip having one of the set of strain probes disposed thereon.

23. The electronic device of claim 20, further comprising:

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

24. The electronic device of claim 20, 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 ac the interior surface of the cover glass within the opaque border region and connected on a second side to the elastomeric border.