Stretchable touchpad of the capacitive type

Patent metadata

Field	Value
Publication number	US-10698532-B2
Application number	US-201815880632-A
Country	US
Kind code	B2
Filing date	Jan 26, 2018
Priority date	Jan 27, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

It is disclosed a stretchable touchpad ( 10 ) of the capacitive type including a stretchable textile fabric ( 20 ) having a plurality of conductive elements incorporated therein. The conductive elements are resistive strain gauges ( 30, 40 ) which form electrodes to detect a change of capacitance caused by a touch. It is also disclosed a method for operating a stretchable touchpad ( 10 ) comprising the steps of measuring continuously a capacitance analog signal provided by a resistive strain gauge ( 30, 40 ) of the stretchable touchpad ( 10 ); and comparing the measured capacitance signal with a threshold value in order to determine whether or not a touch has taken place, wherein the threshold value is continuously adjusted as a function of the actual measurement of capacitance and as a function of the resistance of said resistive strain gauges ( 30, 40 ) which form the capacitor electrodes of said touchpad ( 10 ).

First claim

The invention claimed is:

1. A sensing device comprising a stretchable touchpad ( 10 ) of the capacitive type, the stretchable touchpad ( 10 ) including a uni- or bi-directionally stretchable textile fabric ( 20 ) having a plurality of conductive elements incorporated therein, wherein said conductive elements are resistive strain gauges ( 30 , 40 ) which form electrodes that provide a change of capacitance signal caused by a touch, wherein said resistive strain gauges are disposed along perpendicular directions in a bi-directional array, said sensing device comprising a control unit configured to process said signal and configured to compare the measured capacitance signal with a threshold value in order to determine whether or not a touch has taken place, wherein said threshold value is continuously adjusted as a function of the actual measurement of capacitance and as a function of the resistance of resistive strain gauges ( 30 , 40 ) which form the capacitor electrodes of said touchpad ( 10 ).

2. The sensing device according to claim 1 , wherein said resistive strain gauges ( 30 , 40 ) are disposed along perpendicular directions in a bi-directional array and wherein an insulating material ( 50 ) is placed at crossing points ( 60 ) of said resistive strain gauges ( 30 , 40 ).

3. The sensing device according to claim 1 , wherein said resistive strain gauges ( 30 , 40 ) comprise resistive elastomeric coatings screen printed onto the stretchable textile fabric ( 20 ).

4. The sensing device according to claim 1 , wherein said resistive strain gauges ( 30 , 40 ) comprise conductive yarns woven or knitted into the fabric ( 20 ).

5. The sensing device according to claim 1 , wherein said resistive strain gauges ( 30 , 40 ) comprise resistive elastomeric coatings screen printed onto stripes.

6. The sensing device according to claim 1 , wherein said stretchable textile fabric ( 20 ) has different elongation properties in two perpendicular directions.

7. A wearable garment including the sensing device according to claim 1 .

8. A method for operating the sensing device according to claim 1 , the method comprising the steps of:
measuring continuously a capacitance analog signal provided by the stretchable touchpad ( 10 ); and
comparing the measured capacitance signal with a threshold value in order to determine whether or not a touch has taken place,
wherein said threshold value is continuously adjusted as a function of the actual measurement of capacitance and as a function of the resistance of resistive strain gauges ( 30 , 40 ) which form the capacitor electrodes of said touchpad ( 10 ).

9. A method for operating the sensing device according to claim 8 , the method further comprising the steps of:
measuring a variation of the electrical resistance of the resistive strain gauge ( 30 , 40 );
using the measured variation of electrical resistance due to elongation to correct a parasitic capacitance error due to the elongation of the resistive strain gauges ( 30 , 40 ).

10. The sensing device according to claim 1 , wherein said control unit ( 90 ) is connected to said stretchable touchpad ( 10 ) in order to analyze the signal of a parasitic capacitance detected by said touchpad ( 10 ).

Assignees

• Sanko Tekstil Isletmeleri San Ve Tic As

Inventors

• Cobanoglu Özgür
• Zengi Leyla
• Banazili Günes
• Akcay Merve Nagihan
• Loyan Kenan
• Akdemir Özgür
• Caglar Fehim

Classifications

• G01B7/22 Primary

  using change in capacitance · CPC title

• G01L1/2268 Primary

  Arrangements for correcting or for compensating unwanted effects · CPC title

• G06F3/0446

  using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes · CPC title

• G06F3/0418 Primary

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G06F2203/04102

  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 title