Capacitive sensing with interpolating force-sensitive resistor array

• US 9,740,341 B1
• Filed: 07/29/2010
• Issued: 08/22/2017
• Est. Priority Date: 02/26/2009
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Rosenberg, Ilya D., Beguin, Julien G.
• Primary Examiner(s): Lopez, Jose Soto
• Application Number:
  US12/846,497
• Time in Patent Office: 2,581 Days
• Field of Search: 345174
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• 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 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/0233 Character input methods
• CPC Class Codes: G06F 3/0237 using prediction or retrieval techniques
• CPC Class Codes: G06F 3/03545 Pens or stylus
• 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 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• 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
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

An combination interpolating force sensitive resistor (IFSR) array touch sensor and capacitive touch sensor, or a modified IFSR sensor, is configured to detect touches resistively and capacitvely. By comparing resistive and capacitive signals, touches may be accurately characterized. The IFSR array may also be used in conjunction with an active stylus to determine a position of the active stylus relative to the IFSR array.

Claims

1. A device comprising:

an interpolating force-sensitive resistor array touch sensor comprising two layers, a first layer comprising a column of electrodes and a second layer comprising a row of electrodes and a resistive material filling gaps between the electrodes of the first layer and the electrodes of the second layer to act as a linear resistor, the resistive material having an electrical resistance that varies in relation to a force applied to the resistive material; and

non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising;

receiving voltage data from a touch controller coupled to the interpolating force-sensitive resistor array touch sensor;

generating a temporal voltage profile based at least in part on the voltage data, the temporal voltage profile indicating a capacitive effect and a resistive effect over time on the interpolating force-sensitive resistor array touch sensor from a touch input; and

analyzing the temporal voltage profile so as to determine that the temporal voltage profile corresponds to at least one of a resistive touch input or a capacitive touch input.

2. The device of claim 1, wherein the touch controller is configured to characterize the touch input as a finger or non-finger based at least in part upon the temporal voltage profile.

3. The device of claim 1, wherein generating the temporal voltage profile comprises:

pulsing a voltage to a first portion of the interpolating force-sensitive resistor array touch sensor; and

measuring the voltage over time at a second portion of the force-sensitive resistor array.

22. The device of claim 1, wherein the resistive material capacitively couples the electrodes of the first layer with the electrodes of the second layer such that if a charge is applied to one or more particular electrodes of the first layer, the charge is introduced to one or more overlapping electrodes of the second layer.

4. A device comprising:

an interpolating force-sensitive resistor array touch sensor comprising;

a first layer comprising a column of electrodes;

a second layer comprising a row of electrodes; and

a resistive material which fills gaps between the electrodes of the first layer and the electrodes of the second layer and having an electrical resistance that is altered at least in part by a force applied to the resistive material; and

non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising;

receiving voltage data from a touch controller coupled to the interpolating force-sensitive resistor array touch sensor;

generating a temporal voltage profile based at least in part on the voltage data, the temporal voltage profile indicating a capacitive effect and a resistive effect over time on the interpolating force-sensitive resistor array touch sensor from a touch input; and

analyzing the temporal voltage profile so as to determine that the temporal voltage profile corresponds to at least one of a resistive touch input or a capacitive touch input.

5. The device of claim 4, wherein the resistive material acts as a linear resistor which allows the touch controller to interpolate a location of the touch input between intersections of the electrode of the first layer and between intersections of the electrodes of the second layer.

6. The device of claim 4, wherein the touch controller characterizes the touch input as corresponding to a finger or non-finger based at least in part upon a comparison of the resistive effect and the capacitive effect.

7. A method comprising:

pulsing a voltage to a first portion of an interpolating force-sensitive resistor array touch sensor comprising a first layer comprising a column of electrodes, a second layer comprising a row of electrodes, and a resistive material which fills gaps between the electrodes of the first layer and the electrodes of the second layer and having an electrical resistance that varies based at least in part on a pressure applied to the resistive material;

measuring a voltage generated by a signal associated with a touch over time at a second portion of the force-sensitive resistor array;

generating a temporal voltage profile from the measured voltage over time, wherein the temporal voltage profile comprises capacitive effects between the electrodes of the first layer and the electrodes of the second layer and resistive effects between the electrodes of the first layer and the electrodes of the second layer; and

analyzing the temporal voltage profile so as to determine that the temporal voltage profile corresponds to at least one of a resistive touch input or a capacitive touch input.

8. The method of claim 7, further comprising characterizing the touch input at the touch sensor, the characterizing comprising:

determining when a voltage spike associated with capacitive coupling of a portion of the array is present within the temporal voltage profile;

determining when a steady state voltage over a pre-determined period of time associated with a resistive contact within a portion of the array is present within the temporal voltage profile;

when the voltage spike and the steady state voltage are present, categorize the touch input as a user touch; and

when the voltage spike is absent and the steady state voltage is present, categorize the touch input as a non-user touch.

9. A device comprising:

an interpolating force-sensitive resistor array touch sensor comprising a first layer comprising a column of electrodes, a second layer comprising a row of electrodes, and a resistive material which fills gaps between the electrodes of the first layer and the electrodes of the second layer and having an electrical resistance that changes based at least in part on a pressure applied to the resistive material; and

non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising;

receiving voltage data from a touch controller coupled to the interpolating force-sensitive resistor array touch sensor;

generating a temporal voltage profile based at least in part on the voltage data, the temporal voltage profile indicating a capacitive effect and a resistive effect over time on the interpolating force-sensitive resistor array touch sensor from a touch input; and

analyzing the temporal voltage profile so as to determine that the temporal voltage profile corresponds to at least one of a resistive touch input or a capacitive touch input.

10. The device of claim 9, wherein the touch controller is further configured to characterize the touch input as corresponding to a finger or a non-finger based at least in part upon a comparison of the resistive effect and the capacitive effect associated with the touch input.

11. The device of claim 9, the operations further comprising:

communicating with an active stylus; and

determining a position of the active stylus relative to the touch sensor.

12. The device of claim 11, wherein the touch sensor emits a signal and the active stylus is configured to receive the signal and determine a position relative to the touch sensor.

13. The device of claim 11, wherein the touch sensor emits the signal at a particular time and receives from the active stylus an indication that the signal was received at the particular time.

14. The device of claim 11, wherein the active stylus emits a second signal and the touch sensor is configured to receive the second signal.

15. A device comprising:

a composite touch sensor comprising;

a capacitive touch sensor;

an interpolating force-sensitive resistor array touch sensor disposed adjacent to and coincident with the capacitive touch sensor, the interpolating force-sensitive resistor array touch sensor comprising a first layer comprising a column of electrodes, a second layer comprising a row of electrodes, and a third layer between the electrodes of the first layer and second layer including a resistive material filling gaps between the electrodes of the first layer and the electrodes of the second layer and having an electrical resistance that is altered at least by changes in a force applied to the resistive material; and

non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising;

receiving voltage data from a touch controller coupled to the interpolating force-sensitive resistor array touch sensor;

generating a temporal voltage profile based at least in part on the voltage data, the temporal voltage profile indicating a capacitive effect and a resistive effect over time on the interpolating force-sensitive resistor array touch sensor from a touch input; and

analyzing the temporal voltage profile so as to determine that the temporal voltage profile corresponds to at least one of a resistive touch input or a capacitive touch input.

16. The device of claim 15, wherein the interpolating force-sensitive resistor array touch sensor is positioned between a point of contact and the capacitive touch sensor.

17. The device of claim 15, wherein the operations further comprise characterizing the touch input based at least in part upon a comparison of output from the touch sensors.

18. A method comprising:

receiving a first input from an interpolating force-sensitive resistor array touch sensor comprising a first layer comprising a column of electrodes, a second layer comprising a row of electrodes and a third layer between the electrodes of the first layer and the second layer including a resistive material filling gaps between the electrodes of the first layer and the electrodes of the second layer and having an electrical resistance that varies in relation to an amount of pressure applied to the resistive material, the first input representing resistive effects detected by the interpolating force-sensitive resistor array touch sensor;

receiving a second input from a capacitive touch sensor disposed adjacent to the interpolating force-sensitive resistor array touch sensor, the second input representing capacitive effects detected by the capacitive touch sensor;

generating a temporal voltage profile based at least in part on the first input and the second input, the temporal voltage profile indicating the capacitive effects and resistive effects over time; and

analyzing the temporal voltage profile so as to determine that the temporal voltage profile corresponds to at least one of a resistive touch input or a capacitive touch input.

19. The method of claim 18, wherein the touch input is characterized as:

a first touch type when the capacitive touch sensor and the interpolating force-sensitive resistor array touch sensor report the touch input at substantially the same location;

or

a second touch type when the capacitive touch sensor reports no touch input at a location and the interpolating force-sensitive resistor array touch sensor reports the touch input at the location.

20. The method of claim 19, wherein the first touch type comprises a finger or hand and the second touch type comprises an inanimate object.

21. The method of claim 19, wherein the resistive material acts as a linear resistor which allows a touch controller to interpolate the location of the touch input between intersections of the electrode of the first layer and between intersections of the electrodes of the second layer.