Frustrated Total Internal Reflection and Capacitive Sensing

• US 20140092052A1
• Filed: 09/28/2012
• Published: 04/03/2014
• Est. Priority Date: 09/28/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Grunthaner, Martin P., Richards, Peter W., Hotelling, Steven P., Teil, Romain A.
• Granted Patent: US 9,891,759 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

Detecting force and touch using FTIR and capacitive location. FTIR determines applied force by the user'"'"'s finger within infrared transmit lines on a touch device. A pattern of such lines determine optical coupling with the touch device. Capacitive sensing can determine (A) where the finger actually touches, so the touch device more accurately infers applied force; (B) whether finger touches shadow each other; (C) as a baseline for applied force; or (D) whether attenuated reflection is due to a current optical coupling, or is due to an earlier optical coupling, such as a smudge on the cover glass. If there is attenuated reflection without actual touching, the touch device can reset a baseline for applied force for the area in which that smudge remains. Infrared transmitters and receivers are positioned where they are not visible to a user, such as below a frame or mask for the cover glass.

Claims

1. Apparatus including

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

one or more infrared emitters;

one or more infrared detectors; and

one or more elements capable of determining one or more measures of attenuated reflection of infrared light between said infrared emitters and said infrared detectors;

said touch device including one or more capacitive sensors capable of detecting one or more contacts on a surface of said touch device; and

said touch device being capable of determining one or more amounts of applied force, and locations thereof, in response to said measures of attenuated reflection and said contacts.

2. Apparatus as in claim 1, wherein

one or more of:

said infrared emitters, said infrared detectors, are positioned below a substantially opaque mask on a surface of said touch device.

3. Apparatus as in claim 1, wherein

one or more of:

said infrared emitters, said infrared detectors, are positioned substantially to a side of a frame holding a surface of said touch device.

4. Apparatus as in claim 1, wherein

said elements capable of determining one or more measures of attenuated reflection include a determination of whether infrared light reflected from a surface of a cover glass is attenuated at an interface between said cover glass and a contact by a user.

5. Apparatus as in claim 1, wherein

said touch device is disposed to determine said amounts of applied force in response to one or more of:

an area of contact on a surface of said touch device;

a degree of wetting between said user and a surface of said touch device;

or

a measure of optical contact between said user and a surface of said touch device.

6. Apparatus as in claim 1, wherein

said touch device is disposed to determine said locations of applied force in response to one or more of:

a determination of shadowing of a first contact and a second contact on a surface of said touch device;

or

a determination of location of a contact in response to said capacitive sensors.

7. Apparatus as in claim 1, including

in response to said measure of attenuated reflection, and

in response to said detecting one or more contacts,

a processor capable of determining a baseline of applied force at one or more locations on said touch device.

8. Apparatus as in claim 7, wherein

said baseline is responsive to a smudge or wetting left on a surface of said touch device.

9. Apparatus as in claim 1, wherein

said infrared light is substantially reflected from one or more of:

an interface including a first surface of said touch device, or an interface including a second surface of a cover of said touch device.

10. Apparatus as in claim 9, wherein

said infrared light is substantially reflected from said interface including a first surface of said touch device when said interface is not coupled said user, and is substantially attenuated when said interface is coupled to said user.

11. Apparatus as in claim 9, wherein

said touch device is disposed to determine said amounts of applied force in response to a set of paths of said infrared light, said infrared light on said set of paths being either

substantially reflected from said interface including a first surface of said touch device;

or

substantially attenuated from said interface.

12. Apparatus as in claim 1, wherein

said infrared light includes a plurality of wavelengths.

13. Apparatus as in claim 1, wherein

said infrared light includes a plurality of wavelengths;

and including

a tuner coupled to at least one of;

said infrared emitters, or said infrared detectors, wherein one or more of said wavelengths are responsive to said tuner.

23. Apparatus as in claim 1, wherein

one or more of:

said infrared emitters, or said infrared detectors, are disposed in a display element, and emit said infrared light as an additional color substantially not at a visible wavelength.

24. Apparatus as in claim 1, wherein

said infrared light has an angle of travel;

and including a tuner coupled to at least one of;

said infrared emitters, or said infrared detectors,

wherein said infrared light has an angle of travel responsive to said tuner.

25. Apparatus as in claim 1, wherein

said infrared light has an angle of travel responsive to a tuner;

said tuner is responsive to one or more of;

a humidity of an ambient environment;

a temperature of said ambient environment;

another aspect of said ambient environment;

or

an aspect of a user interface.

26. Apparatus as in claim 1, wherein

said measures of attenuated reflection of infrared light are responsive to an angle of travel of said infrared light.

27. Apparatus as in claim 1, wherein

said measures of attenuated reflection of infrared light are responsive to an angle of travel of said infrared light;

said angle of travel is tunable in response to one or more of;

a selection of one or more infrared emitters or one or more infrared detectors;

a time at which said infrared light is transmitted.

14. A method, including steps of

determining one or more measures of attenuated reflection of infrared light from a contactable surface of a touch device;

determining one or more measures of capacitive touch sensing on said surface; and

determining an amount of applied force in response to said measures of attenuated reflection and said measures of capacitive touch sensing.

15. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include one or more of:

emitting or detecting infrared light from a location not substantially viewable from said surface.

16. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include determining whether infrared light reflected from a surface of a cover glass is attenuated at an interface between said cover glass and a contact by a user.

17. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include detecting one or more of:

an area of contact on a surface of said touch device;

a degree of wetting between said user and a surface of said touch device;

or

a measure of optical contact between said user and a surface of said touch device.

18. A method as in claim 14, wherein

said steps of determining said measures of capacitive touch sensing include detecting one or more of:

a determination of shadowing of a first contact and a second contact on a surface of said touch device;

or

a determination of location of a contact in response to said capacitive sensors.

19. A method as in claim 14, including steps of

determining a baseline of applied force at one or more locations on said touch device, said baseline being responsive to one or more of:

said measure of attenuated reflection, or said measure of capacitive touch sensing.

20. A method as in claim 19, wherein

said baseline is responsive to a smudge or wetting left on a surface of said touch device.

21. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection are responsive to a plurality of wavelengths.

22. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include tuning one or more wavelengths for one or more emitters or detectors of infrared light.

28. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include transmitting or receiving said infrared light to or from a display element as an additional color substantially not at a visible wavelength.

29. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include transmitting or receiving said infrared light at an angle of travel;

and including steps of tuning said angle of travel.

30. A method as in claim 14, wherein

said steps of determining one or more measures of attenuated reflection include transmitting or receiving said infrared light at a tunable angle of travel;

said tunable angle of travel is responsive to one or more of;

a humidity of an ambient environment;

a temperature of said ambient environment;

another aspect of said ambient environment;

an aspect of a user interface;

a selection of one or more infrared emitters or one or more infrared detectors;

or

a time at which said infrared light is transmitted.

31. A touch device including

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

one or more energy emitters;

one or more energy detectors; and

one or more elements capable of determining one or more measures of attenuated reflection of energy transmitted on a detection line between said energy emitters and said energy detectors, wherein an applied force to a surface of said touch device on said detection line can be detected;

said detection line being modified with respect to its associated energy emitter or its associated energy detector in response to a time value; and

said force sensors being capable of determining one or more amounts of applied force, and locations thereof, in response to said measures of attenuated reflection with respect to a plurality of said detection lines.

32. Apparatus as in claim 31, wherein

an energy transmitted on said detection line includes a plurality of sending times.

33. Apparatus as in claim 31, wherein

at least some said energy emitters include acoustic energy emitters;

and

at least some said energy emitters include electromagnetic energy emitters.

34. Apparatus as in claim 31, wherein

said detection line is responsive to a periodic selection of at least one of:

said energy emitter, said energy detector.

35. Apparatus as in claim 31, wherein

said energy detectors are disposed to receive acoustic energy from more than one of said energy emitters.

36. A method of operating a touch device, including steps of

emitting energy from one or more energy emitters along one or more detection lines to one or more energy detectors, wherein an applied force on a surface of said touch device at a particular one of said detection lines causes an attenuation of said energy on said detection line;

measuring said attenuation in response to said particular one of said detection lines;

altering said detection line in response to a time value; and

determining an amount and location of said applied force in response to said measures of attenuated reflection with respect to a plurality of said detection lines.

37. A method as in claim 36, wherein

an energy transmitted on said detection line includes a plurality of sending times.