User interface incorporating strain gauges

Patent metadata

Field	Value
Publication number	US-2018058837-A1
Application number	US-201715671983-A
Country	US
Kind code	A1
Filing date	Aug 8, 2017
Priority date	Aug 24, 2016
Publication date	Mar 1, 2018
Grant date	—

Abstract

A device includes a substrate, strain gauges, and a controller coupled to the strain gauges. The substrate has a front surface and an opposing rear surface, the front surface including a button representation and the rear surface including a button area corresponding to the button representation. The strain gauges are mounted on the rear surface in proximity to the button area. The controller receives information indicating multiple electrical signal amplitudes, each of the electrical signal amplitudes corresponding to one strain gauge of the plurality of strain gauges, each electrical signal amplitude representing an amount of deformation of the corresponding strain gauge. The controller estimates a location of a pressure applied and/or the magnitude of force applied on the front surface of the substrate based on the received information. The controller also can receive location information of multiple user presses from a separate set of sensors.

First claim

What is claimed is:

1 . A device comprising:
a substrate having a front surface and an opposing rear surface, the front surface including a button representation and the rear surface including a button area corresponding to the button representation; a plurality of strain gauges mounted on the rear surface in proximity to the button area; and a controller coupled to the plurality of strain gauges, the controller configured to:
receive information indicating multiple electrical signal amplitudes, each of the electrical signal amplitudes corresponding to one strain gauge of the plurality of strain gauges, each electrical signal amplitude representing an amount of deformation of the corresponding strain gauge; and
estimate a location of a pressure applied on the front surface of the substrate based on the received information.

2 . The device of claim 1 , the controller further configured to estimate a force applied at the location.

3 . The device of claim 2 , the controller further configured to identify, based on the estimated location, the estimated force, or the estimated location and the estimated force, a valid user input indicating a push of the button representation on the front surface of the substrate.

4 . The device of claim 3 , wherein the controller is configured to identify the valid user input in a circumstance in which the electrical signal amplitudes corresponding to the plurality of strain gauges are approximately equal.

5 . The device of claim 3 , wherein the controller is configured to identify the valid user input in a circumstance in which each of the electrical signal amplitudes is greater than a threshold amplitude.

6 . The device of claim 1 , further comprising at least one center strain gauge mounted on the rear surface of the substrate such that at least a portion of each of the at least one center strain gauge overlaps with the button area, wherein, for each of the at least one center strain gauge, the controller is configured to receive information regarding amplitude of an electrical signal corresponding to the center strain gauge, and the controller is further configured to identify a valid user input based on one or more of the electrical signal amplitudes corresponding to a respective one or more of the at least one center strain gauge.

7 . The device of claim 6 , wherein the controller is further configured to identify a valid user input based on one or more of the electrical signal amplitudes corresponding to a respective one or more of the at least one center strain gauge being greater than the electrical signal amplitudes corresponding to the plurality of strain gauges.

8 . The device of claim 6 , wherein the controller is further configured to identify a valid user input based on one or more of the electrical signal amplitudes corresponding to a respective one or more of the at least one center strain gauge being greater than a threshold amplitude.

9 . The device of claim 6 , wherein the at least one center strain gauge is positioned within a boundary of the button area.

10 . The device of claim 1 , wherein the substrate comprises stainless steel.

11 . A device comprising:
a substrate having a front surface and an opposing rear surface, the front surface including a button representation and the rear surface including a button area corresponding to the button representation; a ring mounted on the rear surface in proximity to the button area, an inner periphery of the ring defining an isolated area on the rear surface; at least one strain gauge mounted on the isolated area on the rear surface; and a controller coupled to the at least one strain gauge, configured to:
receive information indicating an amplitude of an electrical signal corresponding to the at least one strain gauge, and
identify a valid user input based on the received information.

12 . The device of claim 11 , wherein the controller is configured to identify a valid user input when the amplitude of the electrical signal corresponding to the at least one strain gauge is greater than a threshold amplitude.

13 . The device of claim 11 , wherein a thickness of the ring is about 2 to about 5 times a thickness of the substrate.

14 . A device comprising:
a substrate having a front surface and an opposing rear surface, the front surface including one or more button representations; a strain gauge mounted on the rear surface; a controller coupled to the strain gauge, configured to: receive information representing an amplitude value, the amplitude value representing an amplitude of an electrical signal associated with the strain gauge; estimate a location of a pressure on the front surface of the substrate based on the received information.

15 . The device of claim 14 , wherein the amplitude value is a first value, further comprising an arrangement of strain gauges including the strain gauge, wherein the controller is further configured to receive information representing a plurality of amplitude values including the first value, each amplitude value representing an amplitude of an electrical signal associated with a respective strain gauge of the arrangement of strain gauges.

16 . The device of claim 15 , wherein the controller is further configured to estimate a location of a pressure on the front surface of the substrate based on the received information representing the plurality of amplitude values.

17 . The device of claim 16 , wherein the controller is further configured to estimate a force magnitude of a pressure on the front surface of the substrate based on the received information representing the plurality of amplitude values.

18 . The device of claim 17 , wherein the controller is configured to estimate the force magnitude and the location of the pressure by processing the received information using a model.

19 . The device of claim 18 , wherein the model is based on analytical models of the substrate and the strain gauges.

20 . The device of claim 18 ,
wherein the model includes a plurality of predefined sets, each set corresponding to a different combination of predefined values of force magnitude, location on the front surface of the substrate, and multiple amplitude values; and wherein the controller is configured to:
compare the plurality of amplitude values associated with the arrangement of strain gauges to the plurality of predefined sets, and
identify in the plurality of predefined sets a predefined set that results in a best match to the plurality of amplitude values associated with the arrangement of strain gauges, and
use the force magnitude and location on the front surface of the substrate corresponding to the predefined set resulting in a best match as an estimate for an actual force magnitude and an actual location of the pressure on the front surface of the substrate.

21 . The device of claim 20 , wherein the controller is further configured to:
compare the plurality of amplitude values associated with the arrangement of strain gauges with the plurality of predefined sets by determining a plurality of squared error residuals, each squared error residual being between the predefined multiple amplitude values of each set of the plurality of predefined sets and the plurality of amplitude values associated with the arrangement of strain gauges; determine a minimum squared error residual from the plurality of squared error residuals, and identify in the plurality of predefined sets a predefined set that results in a bes

Assignees

• Knowles Electronics Llc

Inventors

• Dektor Shandor
• Unruh Andrew
• Ali Asad
• Verma Tony

Classifications

• G01B7/003

  for measuring position, not involving coordinate determination (coordinate measuring G01B7/004) · CPC title

• G01B7/16 Primary

  for measuring the deformation in a solid, e.g. by resistance strain gauge · CPC title

• H03K17/9625 Primary

  using a force resistance transducer · CPC title

• H03K2217/96058

  Fail-safe touch switches, where switching takes place only after repeated touch · CPC title