Electronic device with an integrated touch sensing and force sensing device

• US 9,690,408 B1
• Filed: 09/26/2014
• Issued: 06/27/2017
• Est. Priority Date: 09/26/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Krah, Christoph H.
• Primary Examiner(s): Chow, Van
• Application Number:
  US14/498,556
• Time in Patent Office: 1,005 Days
• 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 3/016 Input arrangements with force or tactile feedback as computer generated output to the user
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

An integrated touch sensing and force sensing device is included in an electronic device. The integrated touch sensing and force sensing device includes a force-sensitive layer operably attached to an input surface, a first electrode layer attached to a first surface of the force-sensitive layer, and a second electrode layer attached to a second surface of the force-sensitive layer. An analog front end processing channel is operable to process a touch signal that is based on a change in an electrical property between the first and second electrode layers and operable to process a force signal that is based on an electrical property generated by the force-sensitive layer based on a force applied to the input surface.

Claims

1. An electronic device, comprising:

an integrated touch sensing device and force sensing device, comprising;

an input surface;

a force-sensitive layer attached to the input surface;

a first electrode layer attached to a first surface of the force-sensitive layer, the first electrode layer comprising a set of discrete electrodes; and

a second electrode layer attached to a second surface of the force-sensitive layer; and

an analog front end (AFE) processing channel operably connected to the integrated touch sensing device and force sensing device, the AFE processing channel configured to process a touch signal that is based on a change in an electrical property between the first and the second electrode layers and configured to process a force signal that is based on an electrical property generated by the force-sensitive layer, the AFE processing channel comprising;

a receiver AFE channel operably connected to at least one respective discrete electrode in the set of discrete electrodes;

a touch processing channel operably connected to an output of the receiver AFE channel; and

a force processing channel operably connected to the output of the receiver AFE channel.

2. The electronic device as in claim 1, wherein the receiver AFE channel comprises:

a first input of an amplifier operably connected to the at least one respective discrete electrode in the set of discrete electrodes;

a second input of the amplifier operably connected to a bias signal;

an analog-to-digital converter operably connected to an output of the amplifier; and

a feedback capacitor connected between the first input of the amplifier and the output of the amplifier.

3. The electronic device as in claim 2, wherein:

the force processing channel comprises;

an error comparator operably connected to the output of the receiver AFE channel; and

a decimation filter and error correction circuit operably connected to an output of the error comparator; and

the AFE processing channel further comprises a feedback current digital-to-analog circuit operably connected between the output of the error comparator and the first input of the amplifier in the receiver AFE channel.

4. The electronic device as in claim 1, wherein the touch processing channel comprises:

a demodulator operably connected to the output of the receiver AFE channel; and

an accumulator operably connected to an output of the demodulator.

5. The electronic device as in claim 1, wherein the force processing channel comprises a decimation filter and error correction circuit operably connected to the output of the receiver AFE channel.

6. The electronic device as in claim 5, wherein the decimation filter and error correction circuit corrects an error in the force signal produced using one of adaptive offset compensation, base-lining, and adaptive filtering.

7. The electronic device as in claim 1, wherein the set of discrete electrodes comprises a first set of discrete electrodes and the second electrode layer comprises a second set of discrete electrodes.

8. The electronic device as in claim 7, further comprising a touch transmitter channel operably connected to at least one respective discrete electrode in the second set of discrete electrodes, wherein the touch transmitter channel comprises:

a resistor operably connected between the at least one respective discrete electrode in the second set of discrete electrodes and an output of an amplifier; and

a sigma delta analog-to-digital converter connected in parallel with the resistor.

9. The electronic device as in claim 1, further comprising a display layer connected to the force-sensitive layer.

10. The electronic device as in claim 9, wherein the electronic device comprises a smart telephone.

11. The electronic device as in claim 1, wherein the electronic device comprises a track pad.

12. An electronic device, comprising:

an integrated touch sensing device and force sensing device, comprising;

a force-sensitive layer;

a first electrode layer attached to a first surface of the force-sensitive layer, the first electrode layer comprising a set of discrete electrodes; and

a second electrode layer attached to a second surface of the force-sensitive layer; and

an analog front end (AFE) processing channel operably connected to the integrated touch sensing device and force sensing device, the analog AFE processing channel configured to process a touch signal received from the integrated touch sensing device and force sensing device and configured to process a force signal received from the integrated touch sensing device and force sensing device, the analog AFE processing channel comprising;

a receiver AFE channel operably connected to at least one respective discrete electrode in the set of discrete electrodes, the receiver AFE channel comprising;

an input of an amplifier operably connected to the at least one respective discrete electrode in the set of discrete electrodes;

an analog-to-digital converter operably connected to an output of the amplifier;

a feedback capacitor connected between the input of the amplifier and the output of the amplifier; and

a servo/sigma delta analog-to-digital converter connected in parallel with the feedback capacitor, wherein the amplifier and the feedback capacitor process the touch signal and function as an integrator for the servo/sigma delta analog-to-digital converter; and

a touch processing channel operably connected to an output of the receiver AFE channel.

13. The electronic device as in claim 12, wherein:

the set of discrete electrodes of the first electrode layer comprises a first set of discrete electrodes;

the second electrode layer comprises a second set of discrete electrodes;

the amplifier comprises a first amplifier; and

the electronic device further comprises a touch transmitter channel operably connected to at least one respective discrete electrode in the second set of discrete electrodes, the touch transmitter channel comprising;

a resistor operably connected between the at least one respective discrete electrode in the second set of discrete electrodes and an output of a second amplifier; and

a sigma delta analog-to-digital converter connected in parallel with the resistor.

14. The electronic device as in claim 12, wherein the touch processing channel comprises:

a demodulator operably connected to the output of the receiver AFE channel; and

an accumulator operably connected to an output of the demodulator.

15. The electronic device as in claim 12, further comprising a touch power management channel operably connected to an output of the servo/sigma delta analog-to-digital converter.

16. The electronic device as in claim 12, further comprising a demodulator channel operably connected to an output of the servo/sigma delta analog-to-digital converter.

17. The electronic device as in claim 16, further comprising a mechanical oscillator operably connected between the force-sensitive layer and the demodulator channel.

18. The electronic device as in claim 17, wherein the mechanical oscillator is amplitude modulated to produce haptic feedback.

19. An electronic device, comprising:

an integrated touch sensing device and force sensing device, comprising;

a force-sensitive layer;

a first electrode layer attached to a first surface of the force-sensitive layer, the first electrode layer comprising a first set of discrete electrodes; and

a second electrode layer attached to a second surface of the force-sensitive layer, the second electrode layer comprising a second set of discrete electrodes;

a touch transmitter channel operably connected to at least one respective discrete electrode in the second set of discrete electrodes; and

an analog front end (AFE) processing channel operably connected to the integrated touch sensing device and force sensing device, the AFE processing channel configured to process a touch signal that is received from the integrated touch sensing device and force sensing device and configured to process a force signal that is received from the integrated touch sensing device and force sensing device, the AFE processing channel comprising;

a receiver AFE channel operably connected to at least one respective discrete electrode in the first set of discrete electrodes; and

a touch processing channel operably connected to an output of the receiver AFE processing channel.

20. The electronic device as in claim 19, wherein the touch processing channel comprises:

a demodulator operably connected to the output of the receiver AFE channel; and

an accumulator operably connected to an output of the demodulator.

21. The electronic device as in claim 19, further comprising a force processing channel operably connected to the output of the receiver AFE channel.

22. The electronic device as in claim 21, wherein the force processing channel comprises a decimation filter and error correction circuit operably connected to the output of the receiver AFE channel.

23. The electronic device as in claim 19, further comprising a touch power management channel operably connected to the output of the receiver AFE channel.

24. The electronic device as in claim 19, further comprising a demodulator channel operably connected to the output of the receiver AFE channel.

25. The electronic device as in claim 24, further comprising a mechanical oscillator operably connected between the force-sensitive layer and the demodulator channel.