Shear force detection using capacitive sensors

Patent metadata

Field	Value
Publication number	US-9229592-B2
Application number	US-201313827138-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Mar 14, 2013
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

An input device having a sensing region overlapping an input surface includes a first substrate, a second substrate physically coupled to the first substrate, and a sensor electrode disposed on the first substrate and configured to detect input objects in the sensing region. A first force sensor includes a first electrode disposed on the first substrate and a first conductive portion of the second substrate capacitively coupled with the first electrode. The first conductive portion is configured to move relative to the first electrode such that a first variable capacitance of the first force sensor changes in response to force applied to the input surface in a first direction parallel to the touch surface.

First claim

The invention claimed is:

1. An input device having a sensing region overlapping an input surface of the input device, the input device comprising:
a first substrate;
a second substrate physically coupled to the first substrate;
at least one sensor electrode disposed on the first substrate, the at least one sensor electrode configured to detect input objects in the sensing region;
a first force sensor comprising:
a first force sensor electrode disposed on the first substrate; and
a first conductive portion of the second substrate capacitively coupled with the first force sensor electrode, the first conductive portion configured to move relative to the first force sensor electrode such that a first variable capacitance of the first force sensor changes in response to force applied to the input surface in a first direction parallel to the touch surface; and

a second force sensor comprising:
a second force sensor electrode disposed on the first substrate;
a second conductive portion of the second substrate capacitively coupled with the second force sensor electrode, the second conductive portion configured to move relative to the second force sensor electrode such that a second variable capacitance of the second force sensor changes in response to force applied to the input surface in a second direction different from the first direction and parallel to the input surface; and
a third force sensor electrode disposed on the first substrate, the third force sensor electrode capacitive coupled to the second force sensor electrode and configured to move relative to the second conductive portion such that the second variable capacitance changes in response to parallel relative motion between the first substrate and the second substrate, the third force sensor electrode being a transmitter electrode configured to transmit transmitter signals, and the second force sensor electrode being a receiver electrode configured to receive resulting signals, and the resulting signals being indicative of the second variable capacitance and comprising effects from the transmitter signals and the second conductive portion.

2. The input device of claim 1 , wherein force applied to the input surface in a direction perpendicular to the input surface moves the first force sensor electrode relative to the first conductive portion and the second force sensor electrode relative to the second conductive portion, and changes at least one of the first and second variable capacitances.

3. The input device of claim 1 , the first force sensor further comprising:
a first area of overlap between the first force sensor electrode and the first conductive portion, the first area of overlap configured to vary in response to a parallel relative motion between the first substrate and the second substrate.

4. The input device of claim 3 , the second force sensor further comprising:
a second area of overlap between the second force sensor electrode and the second conductive portion, the second area of overlap configured to remain substantially constant in response to the parallel relative motion between the first substrate and the second substrate.

5. The input device of claim 3 , the second force sensor further comprising:
a second area of overlap between the second force sensor electrode and the second conductive portion, the second are of overlap configured to vary in response to a rotational relative motion between the first substrate and the second substrate.

6. The input device of claim 1 , wherein the second substrate consists of a conductive material and the first force sensor further comprises:
a first area of overlap between the first force sensor electrode and an aperture formed in the second substrate, wherein a force applied in a direction parallel to the input surface varies the first area of overlap and changes the first variable capacitance.

7. The input device of claim 1 , wherein the first conductive portion of the second substrate of the first force sensor comprises a conductive material disposed on the second substrate.

8. The input device of claim 1 , further comprising:
a processing system communicatively coupled to the at least one sensor electrode and the first and second force sensor electrodes, the processing system configured to:
determine positional information for input objects in the sensing region;
determine a first capacitance value based on the first variable capacitance and a second capacitance value based on the second variable capacitance; and
determine force information for the force applied to the input surface using the first and second capacitance values.

9. An input device comprising a sensing region overlapping an input surface of the input device, the input device comprising:
at least one sensor electrode disposed on a first substrate, the at least one sensor electrode configured to detect input objects in the sensing region of the input device;
a plurality of force sensor electrodes disposed on the first substrate, the first substrate physically coupled to a second substrate and configured to move relative to the second substrate,
the plurality of force sensor electrodes comprising a first force sensor electrode and a second force sensor electrode, the first force sensor electrode being capacitively coupled to the second force sensor electrode, the second force sensor electrode being a transmitter electrode configured to transmit transmitter signals, and the first force sensor electrode being a receiver electrode configured to receive resulting signals;

a first variable capacitance comprising:
a capacitive coupling between at least one force sensor electrode of the plurality of force sensor electrodes disposed on the first substrate and a first conductive portion of the second substrate;

a second variable capacitance comprising:
a capacitive coupling between at least one force sensor electrode of the plurality of force sensor electrodes disposed on the first substrate and a second conductive portion of the second substrate;

wherein a force applied to the input surface in a first direction parallel to the input surface moves the first substrate relative to the second substrate and changes at least one of the first and second variable capacitances,
wherein the first force sensor electrode is configured to move relative to the second conductive portion such that the second variable capacitance changes in response to parallel relative motion between the first substrate and the second substrate, and
wherein the resulting signals are indicative of the second variable capacitance and comprise effects from the transmitter signals and the second conductive portion.

10. The input device of claim 9 , wherein the first variable capacitance remains substantially constant in response to the force applied to the input surface in the first direction parallel to the input surface, wherein the movement of the first substrate relative to the second substrate comprises parallel relative motion.

11. The input device of claim 10 , wherein a force applied to the input surface in a direction perpendicular to the input surface moves the first substrate relative to the second substrate and changes the first variable capacitance.

12. The input device of claim 11 , wherein the second variable capacitance remains substantially constant in response to the force applied to the input surface in a direction perpendicular to the input surface causing movement of the first substrate relative to the second substrate.

13. The input device of claim 9 , wherein the first variable capacitance comprises:
a capacitive coupling between at least two force sensor elec

Assignees

• Synaptics Inc

Inventors

• Bulea Mihai
• Shaw Scott
• Schwartz Adam

Classifications

• G06F3/0414

  using force sensing means to determine a position · CPC title

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/0447

  Position sensing using the local deformation of sensor cells · CPC title

• G06F3/04166

  Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184) · CPC title

• G06F3/04142 Primary

  the force sensing means being located peripherally, e.g. disposed at the corners or at the side of a touch sensing plate · CPC title