Device and method for localized force sensing

• US 9,075,095 B2
• Filed: 03/15/2013
• Issued: 07/07/2015
• Est. Priority Date: 02/27/2013
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Kallassi, Pascale El, Mackey, Bob, Hsieh, Lin-Hsiang
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): DAVIS HOLLINGTON, OCTAVIA L
• Application Number:
  US13/838,003
• Publication Number:
  US 20140238152A1
• Time in Patent Office: 844 Days
• Field of Search: 738/626.26
• US Class Current: 1/1
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• 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 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 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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 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

A device and method for operating a capacitive input device configured to sense input objects and their applied force in a sensing region, the device including a pliable component having an input surface and characterized by a bending stiffness, and first and second arrays of sensor electrodes. The input device further includes a third array of sensor electrodes and a spacing layer disposed between the third array. The pliable component is characterized by a compressive stiffness and configured to deform in response to a force applied to the input surface and to deflect the second array of sensor electrodes towards the third array of sensor electrodes, wherein the deformation of the input surface and the deflection of the second array of sensor electrodes is a function of the ratio of the bending stiffness of the pliable component and the compressive stiffness of the spacing layer.

Claims

1. A capacitive input device configured to sense input objects in a sensing region, the capacitive input device comprising:

a pliable component comprising an input surface configured to be touched by a user, a first array of sensor electrodes; and

a second array of sensor electrodes, the pliable component characterized by a bending stiffness;

a third array of sensor electrodes; and

a spacing layer disposed between the third array of sensor electrodes and the pliable component, the spacing layer characterized by a compressive stiffness;

wherein, in response to a force applied to the input surface, the input surface is configured to deform and the pliable component is configured to deflect at least one of the second array of sensor electrodes towards the third array of sensor electrodes; and

wherein the deformation of the input surface and the deflection of the second array of sensor electrodes is based on the bending stiffness of the pliable component and the compressive stiffness of the spacing layer.

2. The input device of claim 1, wherein the deformation of the input surface and the deflection of the second array of sensor electrodes is based on a ratio of the bending stiffness of the pliable component to the compressive stiffness of the spacing layer.

3. The input device of claim 1, wherein the force applied to the input surface deflects a subset of the second array of sensor electrodes towards the third array.

4. The input device of claim 1, wherein the pliable component is configured to deform in response to a force applied to the input surface such that at least one sensor electrode of the second array of sensor electrodes deflects towards the third array of sensor electrodes and at least one sensor electrode of the second array of sensor electrodes remains substantially stationary relative to the third array of sensor electrodes.

5. The input device of claim 1, wherein the spacing layer comprises at least one of:

a closed cell porous material;

an open cell porous material;

an adhesive;

pyramid-shaped structures; and

a grid structure.

6. The input device of claim 1, wherein each of the first, second, and third arrays comprise a plurality of electrodes, and wherein the electrodes of the first array are substantially parallel to the electrodes of the third array.

7. The input device of claim 1, wherein the spacing layer comprises an array of compressible structures having a substantially uniform spring constant.

8. The input device of claim 7, wherein the array of compressible structures in the spacing layer are formed on a substrate, wherein the third array of sensor electrodes are disposed between the substrate and the spacing layer.

9. The input device of claim 1, further comprising a processing system communicatively coupled to the first, second, and third arrays of sensor electrodes, the processing system configured to:

measure a first capacitive coupling between at least two of;

the first array of sensor electrodes;

the second array of sensor electrodes; and

an input object in the sensing region;

measure a second capacitive coupling between the third array of sensor electrodes and the second array of sensor electrodes;

determine positional information for the input object in the sensing region based on a change in at least one of the first and second capacitive coupling; and

determine force information for an input object interacting with the input surface based on a change in the second capacitive coupling.

10. The input device of claim 9, wherein the processing system is further configured to distinguish conductive input objects from non-conductive input objects based on the first and second capacitive coupling.

11. An electronic system comprising:

a pliable component characterized by a bending stiffness, the pliable component comprising an input surface configured to be touched by a user, a first array of sensor electrodes; and

a second array of sensor electrodes;

a third array of sensor electrodes;

a spacing layer characterized by a compressive stiffness and disposed between the pliable component and the third array of sensor electrodes;

wherein, in response to applied force to the input surface, the input surface is configured to deform and the pliable component is configured to deflect towards the third array as a function of the bending stiffness of the pliable component and the compressive stiffness of the spacing layer; and

a processing system communicatively coupled to the first, second, and third arrays, the processing system configured to;

drive a transmitter signal onto a sensor electrode of the second array;

receive a first resulting signal from a sensor electrode of the first array, wherein the first resulting signal comprises effects of the capacitive coupling between the sensor electrode of the second array and the sensor electrode of the first array;

receive a second resulting signal from a sensor electrode of the third array, wherein the second resulting signal comprises effects of capacitive coupling between the sensor electrode of the third array and the sensor electrode of the second array; and

determine positional and force information for an input object interacting with the input surface based on the first and second resulting signals.

12. The electronic system of claim 11, wherein the spacing layer comprises at least one of:

a closed cell porous material;

an open cell porous material;

an adhesive;

pyramid-shaped structures; and

a grid structure.

13. The input device of claim 12, wherein the spacing layer comprises an array of compressible structures having a substantially uniform spring constant.

14. A processing system for a capacitive input device, the capacitive input device comprising a pliable component, the pliable component comprising an input surface configured to be touched by a user and a first and second array of sensor electrodes, the pliable component disposed above a spacing layer, and the spacing layer disposed above a third array of sensor electrodes;

the processing system communicatively coupled to the first, second, and third array of sensor electrodes and configured to;

operate the first and second array of sensor electrodes to form a variable capacitance between the first and second array of sensor electrodes;

operate the second and third array of sensor electrodes to form a variable capacitance between the second and third array of sensor electrodes;

determine positional information for input objects in contact with the input surface based on a change in the variable capacitance between the first and second array of sensor electrodes; and

determine positional and force information for input objects which cause the input surface to locally deform based on a change in variable capacitance between the second and third array of sensor electrodes.

15. The processing system of claim 14, further configured to determine positional information for input objects in the sensing region and not in contact with the input surface based on an absolute capacitance of at least one of the first and second array of sensor electrodes.

16. The processing system of claim 14, wherein the processing system is configured to form a variable capacitance between the first and second array of sensor electrodes by:

driving a first transmitter signal onto at least one sensor electrode of the second array, and

receiving a first type of resulting signal from at least one sensor electrode of the first array, the first resulting signal corresponding to the first transmitter signal and effects due to the input object in contact with the input surface; and

wherein the processing is configured to form a variable capacitance between the second and third array of sensor electrodes by;

receiving a second type of resulting signal from at least one sensor electrode of the third array, the second resulting signal corresponding to the first transmitter signal and effect from a deflection of the input surface due to the input object in contact with the input surface.

17. The processing system of claim 14, wherein:

the first or second array of sensor electrodes are configured to electrically shield the third array of sensor electrodes from input objects in the sensing region; and

the second array of sensor electrodes is configured to shield the first and third array of sensor electrodes from each other.

18. The processing system of claim 14, wherein:

the first type of resulting signal received by at least one sensor electrode from the first array of sensor electrodes and the second type of resulting signal received by at least one sensor electrode of the third array of sensor electrodes are received before a second transmitter signal is driven onto the at least one sensor electrode of the second array.

19. The processing system of claim 14, wherein the processing system is further configured to determine a capacitive interaction image based on the first and second types of resulting signals, the capacitive interaction image comprising the effects of input objects in the sensing regions and deflection of the input surface due to an input object.

20. The processing system of claim 14, further configured to:

determine a type of input object in the sensing region of the capacitive input device based on the determined positional and force information.