Force Sensing Using Bottom-Side Force Map

• US 20140085213A1
• Filed: 09/21/2012
• Published: 03/27/2014
• Est. Priority Date: 09/21/2012
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Huppi, Brian Q., Leung, Omar Sze, Drzaic, Paul Stephen, Leong, Craig Christopher
• Application Number:
  US13/624,858
• Publication Number:
  US 20140085213A1
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A force sensor incorporated into a touch device, measuring deflection in a device stack, including compressible elements disposed between the device stack and the frame element. When the device stack is deformed, applied force is measured using the compressible elements, using capacitive sensing or strain measurements. The force sensitive sensor provides an applied force image for the touch device'"'"'s surface. The applied force location [X, Y] can be determined from measures of cover glass tilt, force at particular points, and capacitive sensing of touch location.

Claims

1. Apparatus including

a touch device including one or more applied force sensors, said applied force sensors including

a deformable device stack;

a frame element;

a compressible layer positioned in between said device stack and said frame element, said compressible layer including one or more force sensitive elements;

wherein said touch device is responsive to said force sensitive elements, and capable of determining an amount and location of applied force on a surface of said touch device.

2. Apparatus as in claim 1, wherein

said compressible layer includes a compressible structure, said compressible structure being substantially solid and having compressible elements, said compressible elements being substantially smaller than an optical wavelength.

3. Apparatus as in claim 1, wherein

said compressible layer includes a compressible structure, said compressible structure being substantially solid and having compressible elements, said compressible elements having a compression resistance substantially linear in compression with respect to a compression parameter.

4. Apparatus as in claim 1, wherein

said compressible layer includes a compressible structure, said compressible structure being substantially solid and having compressible elements, said compressible elements having a compression resistance substantially polynomial in compression with respect to a compression parameter.

5. Apparatus as in claim 1, wherein

said compressible layer includes one or more of:

a solid compressible element, said solid compressible element including one or more of;

a cylindrical silicone element, a moth eye element, a nanopore element, a pyramidal silicone element.

6. Apparatus as in claim 1, wherein

said compressible layer is positioned between an LED display element and said frame element.

7. Apparatus as in claim 1, wherein

said touch device includes one or more touch sensors,

wherein said touch device is responsive to said touch sensors, and capable of determining a touch location on a surface of said touch device.

8. Apparatus as in claim 1, wherein

said compressible layer includes one or more capacitive sensors;

said touch device is responsive to said capacitive sensors, and capable of determining an amount and location of applied force in response to said capacitive sensors.

9. Apparatus as in claim 8, wherein

in response to said strain gauges, said touch device determining an image of applied force applicable to at least a region of a surface of said touch device.

10. Apparatus as in claim 8, wherein

said capacitive sensors include

a first circuit layer including an element capable of coupling a drive signal to said capacitive sensors, and

a second circuit layer including an element capable of coupling a sense signal from said capacitive sensors.

11. Apparatus as in claim 1, wherein

said compressible layer includes one or more of:

a foam, a gel, a liquid, an optically translucent or transparent substance.

12. Apparatus as in claim 11, wherein

said compressible layer includes a substance having a Poisson'"'"'s ratio of less than approximately 0.48.

13. Apparatus as in claim 1, wherein

said compressible layer includes one or more strain gauges;

said touch device is responsive to said strain gauges, and capable of determining an amount and location of applied force in response to said strain gauges.

14. Apparatus as in claim 13, wherein

in response to said strain gauges, said touch device determining an image of applied force applicable to at least a region of a surface of said touch device.

15. Apparatus as in claim 13, wherein

said strain gauges are responsive to a measure of tilt on said surface of said touch device.

16. A touch device including

one or more applied force sensors, said applied force sensors including

a deformable device stack;

a compressible layer positioned in between said device stack and a substantially rigid element positioned below said device stack, said compressible layer including one or more force sensitive elements;

one or more capacitive touch sensing elements;

wherein said touch device capable of determining an amount and location of applied force on a surface thereof in response to said force sensitive elements and said touch sensing elements.

17. A touch device as in claim 16, wherein

said applied force sensors are responsive to a measure of compression of said compressible layer.

18. A touch device as in claim 16, wherein

said applied force sensors are responsive to a measure of deformation of said device stack.

19. A touch device as in claim 16, wherein

said compressible layer includes at least one nanostructure having a first size and at least one nanostructure having a second size.

20. A touch device as in claim 16, wherein

said compressible layer includes one or more nanostructures having a density that varies with a distance from a substrate.

21. A touch device as in claim 16, wherein

said compressible layer includes one or more of:

a set of nanostructures positioned in a regular pattern, a set of nanostructures positioned in a set of random or pseudorandom locations.

22. A touch device as in claim 16, wherein

said compressible layer includes

a set of nanostructures positioned in a regular pattern, and

a set of nanostructures positioned in a set of random or pseudorandom locations.

23. A touch device as in claim 16, wherein

said compressible layer includes one or more of:

one or more relatively open elements, one or more relatively compressible solid elements.

24. A touch device as in claim 16, wherein

said compressible layer includes a network of:

one or more relatively open elements, and one or more relatively compressible solid elements.

25. A touch device as in claim 16, wherein

said touch device includes a substantially flexible display element positioned above said compressible layer.

26. A touch device as in claim 25, wherein

said substantially flexible display element includes one or more of:

an electrochromic display, an electrofluidic display, an electrokinetic display, an electrophoretic display, a liquid crystal display, a polymer display, a polymer dispersed liquid crystal display, a polymer network liquid crystal display, a microencapsulated cholesteric liquid crystal display.

27. A method, including steps of

determining a measure of applied force on a touch device, in response to one or more force sensitive elements positioned in a compressible layer, said compressible layer being positioned between a deformable device stack and a frame element;

and

determining a location of said applied force in response to said force sensitive elements.

28. A method as in claim 27, including steps of

measuring a compression resistance of said compressible layer;

wherein said compression resistance is substantially linear in compression with respect to a compression parameter.

29. A method as in claim 27, including steps of

measuring a compression resistance of said compressible layer;

wherein said compression resistance is substantially nonlinear in compression with respect to a compression parameter.

30. A method as in claim 27, including steps of

determining a touch location on a surface of said touch device in response to one or more touch sensors.

31. A method as in claim 27, including steps of

measuring a capacitance in response to said compressible layer;

and

determining an amount and location of applied force in response to said stesps of measuring a capacitance.

32. A method as in claim 27, wherein

determining an image of applied force applicable to at least a region of a surface of said touch device.

33. A method of operating a touch device, said method including steps of

determining an amount and location of applied force on a surface of said touch device, in response to one or more force sensitive elements and one or more touch sensing elements;

wherein said force sensitive elements are disposed in a compressible layer positioned in between a substantially deformable device stack and a substantially rigid element positioned below said device stack; and

wherein said touch sensing elements include one or more capacitors.

34. A method of operating a touch device as in claim 33, including steps of

operating a substantially flexible display element positioned above said compressible layer.

35. A method of operating a touch device as in claim 34, wherein

said substantially flexible display element includes one or more of:

an electrochromic display, an electrofluidic display, an electrokinetic display, an electrophoretic display, a liquid crystal display, a polymer display, a polymer dispersed liquid crystal display, a polymer network liquid crystal display, a microencapsulated cholesteric liquid crystal display.