Shear force detection using capacitive sensors

Patent metadata

Field	Value
Publication number	US-9958994-B2
Application number	US-201514952560-A
Country	US
Kind code	B2
Filing date	Nov 25, 2015
Priority date	Mar 14, 2013
Publication date	May 1, 2018
Grant date	May 1, 2018

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 comprising:
a first substrate comprising an array of sensor electrodes configured to sense input objects in a sensing region overlapping an input surface of the input device;
a second substrate physically coupled to the first substrate and configured to move relative to the first substrate in a lateral direction and a vertical direction;
a first force sensor comprising a first force sensor electrode disposed on the first substrate and a first conductive portion disposed on the second substrate, the first force sensor electrode and the first conductive portion forming a first variable capacitance; and
a second force sensor comprising a second force sensor electrode disposed on the first substrate and a second conductive portion disposed on the second substrate, the second force sensor electrode and the second conductive portion forming a second variable capacitance,
wherein, in response to vertical motion of the first substrate relative to the second substrate, the first variable capacitance and the second variable capacitance change,
wherein, in response to lateral motion of the first substrate relative to the second substrate in a first direction, the first variable capacitance changes and the second variable capacitance remains substantially constant, and
wherein, in response to lateral motion of the first substrate relative to the second substrate in a second direction, perpendicular to the first direction, the second variable capacitance changes and the first variable capacitance remains substantially constant.

2. The input device of claim 1 , wherein, in response to the vertical motion of the first substrate relative to the second substrate, a distance between the first force sensor electrode and the first conductive portion of the first force sensor decreases, and a distance between the second force sensor electrode and the second conductive portion of the second force sensor decreases.

3. The input device of claim 1 , wherein, in response to the lateral motion of the first substrate relative to the second substrate in the first direction, the first variable capacitance changes due to a change in an area of overlap between the first force sensor electrode and the first conductive portion.

4. The input device of claim 3 , wherein, in response to the lateral motion of the first substrate relative to the second substrate in the first direction, the second variable capacitance remains substantially constant due to no change in the area of overlap between the second force sensor electrode and the second conductive portion.

5. The input device of claim 3 , wherein, in response to the lateral motion of the first substrate relative to the second substrate in the second direction, the first variable capacitance remains substantially constant due to no change in the area of overlap between the first force sensor electrode and the first conductive portion, and the second variable capacitance changes due to a change in the area of overlap between the second force sensor electrode and the second conductive portion.

6. The input device of claim 1 , wherein, in response to a rotational motion in a first direction between the first substrate and the second substrate, the first variable capacitance and the second variable capacitance both increase, and, in response to a rotational motion in a second direction, opposite the first direction, the first variable capacitance and the second variable capacitance both decrease.

7. The input device of claim 1 , further comprising:
a processing system communicatively coupled to the array of sensor electrodes and the first and second force sensor electrodes, the processing system configured to:
determine positional information for the input objects in the sensing region from the array of sensor electrodes;
drive a sensing signal onto the first force sensor electrode and the second force sensor electrode;
determine the first variable capacitance based on a received resulting signal from the first force sensor electrode;
determine the second variable capacitance based on a received resulting signal from the second force sensor electrode;
determine a first capacitance value based on the first variable capacitance and a second capacitance value based on the second variable capacitance; and
determine the lateral and the vertical force applied to the input surface using the first and second variable capacitance values.

8. The input device of claim 1 , further comprising a third force sensor, the third force sensor comprising a third force sensor electrode disposed on the first substrate and the first conductive portion disposed on the second substrate, the third force sensor electrode and the first conductive portion forming a third variable capacitance, wherein the third variable capacitance remains substantially constant in response to movement of the first substrate relative to the second substrate in a lateral direction and the variable capacitance changes in response to vertical movement of the first substrate relative to the second substrate.

9. The input device of claim 8 , wherein the first force sensor further comprises a force transmitter electrode configured to form the first variable capacitive between the force transmitter electrode, the first force sensor electrode and the first conductive portion, and the third force sensor electrode further comprises the force transmitter electrode configured to form the third variable capacitance between the force transmitter electrode, the third force sensor electrode and the first conductive portion.

10. The input device of claim 9 , further comprising:
a processing system communicatively coupled to the array of sensor electrodes, the first force sensor electrode, the second force sensor electrode, the third force sensor electrode, and the force transmitter electrode, the processing system configured to:
determine positional information for the input objects in the sensing region from the array of sensor electrodes;
drive a sensing signal onto the force transmitter electrode;
determine the first variable capacitance based on a received resulting signal from the first force sensor electrode;
determine the third variable capacitance based on a received resulting signal from the third force sensor electrode;
determine the first capacitance value based on the first variable capacitance and a third capacitance value based on the third variable capacitance; and
determine the lateral and vertical force applied to the input surface using the first capacitance value and the second capacitance value.

11. An input device comprising:
an array of sensor electrodes disposed on a first substrate;
a second substrate physically coupled to the first substrate, wherein in response to a force applied to the first substrate, the first substrate is configured to move in a lateral and vertical direction with respect to the first substrate;
a first force sensor electrode, a second force sensor electrode and a first force transmitter electrode disposed on the first substrate; and
a processing system communicatively coupled to the array of sensor electrodes, the first force sensor electrode, the second force sensor electrode, and the first force transmitter electrode, the processing system is configured to:
determine positional information for input objects in a sensing region of the input device using the array of sensor electrodes;
drive a sensing signal onto the first force transmitter electrode;
receive a first resulting signal from the first force sensor electrode, the first resulting signal comprising effects of the sensing signal driven onto the first force transmitter el

Assignees

• Synaptics Inc

Inventors

• Bulea Mihai
• Shaw Scott
• Schwartz Adam

Classifications

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F2203/04106

  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 title

• G06F3/0414

  using force sensing means to determine a position · CPC title

• G06F3/0447

  Position sensing using the local deformation of sensor cells · 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